applied sciences Article
Design and Research of Double-Sided Linear Switched Reluctance Generator for Wave Energy Conversion Yan Chen 1, *, Min Cao 1 , Chunyan Ma 1 and Zhigang Feng 2 1 2
*
College of Electrical and Power Engineering, Taiyuan University of Technology, Taiyuan 030024, China;
[email protected] (M.C.);
[email protected] (C.M.) Taiyuan Power Supply Section of China Railway Taiyuan Bureau Group Co., Ltd., Taiyuan 030013, China;
[email protected] Correspondence:
[email protected]; Tel.: +86-135-9318-2148
Received: 5 August 2018; Accepted: 17 September 2018; Published: 19 September 2018
Abstract: As a clean and renewable energy source, wave energy is of great significance in solving primary energy shortages and environmental pollution. Direct-drive wave power systems consisting of linear generators have attracted the attention of researchers from various countries. Linear Switched Reluctance Generator has the advantages of simple structure, sturdiness, reliable operation, suitable for harsh environments, and easy maintenance, aiming at the problem of single-sided magnetic pull force and serious coupling of phase winding of traditional linear switched reluctance generator, a Double-sided Linear Switched Reluctance Generator (DLSRG) for wave power generation is designed, and its electromagnetic characteristics (including coupling characteristics, magnetic saturation characteristics, and magnetic tension characteristics) are analyzed to verify the rationality of the structure and parameter selection. Finally, the power generation performance is studied. The joint simulation results show that the structure design of DLSRG is reasonable, overcomes the problem of single-sided magnetic pull force, the phase-to-phase coupling is negligible, and it has continuous power generation capability, and the power generation efficiency is as high as 80.6%. Therefore, DLSRG designed in this paper is suitable for wave power generation. Keywords: double-side linear switched reluctance generator; wave power generation; electromagnetic characteristics; generation characteristics
1. Introduction With the exhaustion of primary energy, there is a serious environmental pollution and energy shortage in the world. Wave power is one of the richest and promising sources of renewable energy for the future, so it is of great significance to study wave power generation to solve the problem of energy shortage. In the past four decades, hundreds of Wave Energy Converters (WEC) have been proposed and studied, but so far a conclusive architecture to harvest wave power has not been identified. At present, according to the wave energy-mechanical energy conversion method, the conventional wave energy power generation technology can be divided into three categories: oscillating water column type power generation [1], contraction channel type power generation [2], and hydraulic wave power generation technology [3–5]. In the early wave power generation system, rotating generators were used as energy converters. The reciprocating wave energy was converted into mechanical energy and then converted into electrical energy because of the need for intermediate conversion devices, such as cylinders, gears, etc. Its structure was complex and difficult to maintain. The efficiency is relatively low [6]. The direct drive Appl. Sci. 2018, 8, 1700; doi:10.3390/app8091700
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wave power generation system consisting of a linear generator eliminates the intermediate conversion device and it has the advantages of simple structure and easy maintenance. In recent years, direct-drive generators have been paid more and more attention by researchers all over the world, there are many types of linear generator including transverse flux linear generator [7], linear synchronous generator [8], permanent magnet linear generator [9] and linear switched reluctance generator [10], etc., especially linear permanent magnet generators have been systematically studied [7]. Linear permanent magnet generators have stable power generation and high output efficiency. However, the price of permanent magnets is high and it is difficult to adapt to the harsh working environment [11,12], which hinders its universal application to some extent. The stator structure of linear switched reluctance generator is simple and strong, and each phase can be controlled independently [13]. It has the advantages of no wear, no lubrication, low speed operation, and so on [14].When compared with the linear permanent magnet generator, the stator of the linear switched reluctance generator is composed of silicon steel laminated, it does not need to install permanent magnet, it is less affected by the external environment, and it can operate under the bad environment, such as high temperature, high corrosion, and other adverse environments, which is more suitable for ocean wave power generation. In the reference [15,16], the single-sided linear switched reluctance generator system is studied; the mutual inductance coupling linear switched reluctance generator has been studied in the reference [11] to improve the efficiency of power generation; Double-sided Linear Switched Reluctance Generator (DLSRG)is studied in the reference [17], which is used to improve the unilateral magnetic tension problem; in the reference [12]; and the optimal efficiency tracking control of generator is studied in detail, and the two-sided mutual inductance coupled switched reluctance generator is chosen as the object of study, which improves the influence of two-sided magnetic pull force. The purpose of this paper is to design a DLSRG based on improving the single-sided magnetic tension of the traditional single-sided linear switched reluctance generator and reducing the coupling characteristics of the phase winding, the structure of the motor is optimized, the electromagnetic characteristics and generation performance are studied. This paper is organized as follows: after the introduction, in Section 2 the basic structure and operation principle of DLSRG are given, in Section 3 Mathematical modeling is given, in Section 4 the electromagnetic characteristics of DLSRG is analyzed, in Section 5 the power generation simulation experiment along with the simulation experiment results are presented, and finally, in Section 6, the conclusions are drawn. 2. The Basic Structure and Operation Principle of DLSRG 2.1. Basic Structure The structure of DLSRG has the advantages of simple structure, easy opening of die, winding by suit, and low requirement for installation and maintenance, and DLSRG operates independently, and the mutual inductance between phase and phase is relatively small, which can be ignored, so the difficulty of control is greatly reduced. The basic structure of DLSRG is shown in Figure 1. The generator has been preliminarily designed following the approach presented in the reference [18]. The optimization has been performed by letting some geometrical parameters be varied in order to achieve maximum transverse magnetic pull and ensure self-generation capability. The stator and the rotor are made of silicon steel sheet (DW465-50), which is thick in 0.5 mm and has a stacking coefficient of 0.9. The excitation windings are arranged on the stator teeth in turn and are fixed by epoxy resin slot wedge. The precision of slot wedge thickness is low, which is easy to fix and install. The stator slot adopts open slot, which requires lower precision of slot wedge thickness, this kind of structure is easy to fix and install. The rotor is fixed on the shell of generator through linear bearing and base, so reciprocating motion can be realized. The DLSRG cross-section diagram is shown in Figure 2. The letter A, B, C represents the three-phase
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represents the three-phase winding, and the three-phase winding adopts the centralized winding. represents thetothree-phase winding, and theeach three-phase winding winding. According the symmetrical structure, phase winding is adopts dividedthe intocentralized two groups and four winding, and the three-phase winding adopts the centralized winding. According to the symmetrical According themagnetic symmetrical structure, each phase divided into two groups and four coils, andtothe loop is formed through the winding excitation.isThe three-phase excitation is different structure, each phase winding is divided into two groups and four coils, and the magnetic loop is coils, and magneticthree-phase loop is formed through the excitation. The three-phase is different from thethe traditional excitation. Traditional three-phase excitation,excitation phase difference is 120 formed through the excitation. The three-phase excitation is different from the traditional three-phase from the traditional three-phase excitation. Traditional three-phase excitation, phase difference is 120 degrees. In DLSRG winding, the three phase excitation is equal, the phase difference is 0, the excitation. Traditional three-phase excitation, phase difference is 120 degrees. In DLSRG winding, degrees. In DLSRG winding, the are three phase structural parameters of DLSRG shown in excitation Table 1. is equal, the phase difference is 0, the the three phase excitation is equal, the phase difference is 0, the structural parameters of DLSRG are structural parameters of DLSRG are shown in Table 1. shown in Table 1.
Figure 1. Basic structure of Double-sided Linear Switched Reluctance Generator (DLSRG). The motor Figure 1. Basic structure of Double-sided Linear Switched Reluctance Generator (DLSRG). The motor Figure 1. Basic structure of Double-sided Linear Switched Reluctancethe Generator (DLSRG). The motor consists of the stator, the rotor, the motor housing, the windings, slot wedges, the linear bearing. consists of the stator, the rotor, the motor housing, the windings, the slot wedges, the linear bearing. consists of the stator, the rotor, the motor housing, the windings, the slot wedges, the linear bearing.
Figure 2. Schematic diagram of DLSRG. TheThe A, B, the three-phase winding. In DLSRG Figure 2. Schematic diagram of DLSRG. A,CB,represents C represents the three-phase winding. In DLSRG winding, three phase excitation is equal, the phase difference is three-phase 0,isthe structural parameters of of Figure 2.the Schematic diagram of DLSRG. A, B, Cphase represents the winding. In DLSRG winding, the three phase excitation isThe equal, the difference 0, the structural parameters DLSRG are shown in Table 1. winding, the three phase excitation is equal, the phase difference is 0, the structural parameters of DLSRG are shown in Table 1.
DLSRG are shown in Table 1. Parameter
Parameter
Statorslot width ss /mm Parameter Statorslot widthss/mm Stator tooth width sp /mm Statorslot widths /mm Stator tooth widths p/mm Statortooth height ssph /mm Stator toothyoke widths p/mm Statortooth heights ph/mm Stator sc /mm Rotor slotheights width /mm Statortooth /mm /mm Stator yokestcsph Rotor tooth width t /mm p c/mms/mm Stator yokes Rotor slot widtht Rotortooth height tph /mm Rotor slot widtht s/mm p/mm Rotor tooth widtht Rotor yoke tc /mm
p/mm Rotor tooth widtht ph/mm Rotortooth heightt /mm Rotortooth Rotorheightt yoketcph /mm 2.2. Operation Principle Rotor yoket c/mm
Table 1. DLSRG parameters. Table 1. DLSRG parameters. Table Numerical Value1. DLSRG parameters. Parameter Numerical Value Numerical Value Parameter Numerical Value 33 Motor body width w/mm 150 Numerical33Value Parameter Numerical Value Motor body widthw/mm 150 33 air gap g/mm 1.5 33 Motor body widthw/mm air gap g/mm 54 33 Stator silicon steel sheet ssi /sheet 3001501.5 33 air gap steel g/mm Stator silicon sheets si/sheet 21 54 Rotor silicon steel sheet tsi /sheet 3001.5300 66 21 number of turns of winding N/circle 273300300 54 Stator silicon steel sheets si/sheet Rotor silicon steel sheett si/sheet 33 66 Enamelled diameter d/mm 1.38 21 Rotor silicon steel si/sheet 300273 number ofwire turns ofsheett windingN/circle 19 1.496 Enamelled wire cross section S/mm2 66 33 number of turnswire of windingN/circle 2731.38 Enamelled diameterd/mm 48 Full tank rate Ks 0.4596 33 19 Enamelled 1.38 Enamelledwire wirediameterd/mm cross sectionS/mm2 1.496 2 19 48 Enamelled wire 1.496 Fullcross tank sectionS/mm rateKs 0.4596 48 Full tank rateKs 0.4596
2.2. Operation Principle The operation of DLSRG follows the principle of magneto resistive minimization [19–21]. When 2.2.DLSRG Operation Principle the inductance is inversely proportional to the reluctance. When the rotor the is running, The operation of DLSRG follows the principle of magneto resistive minimization [19–21]. When tooth is aligned center line of the the principle stator tooth, the inductance thereluctance. phase winding The operation ofthe DLSRG of magneto resistive minimization [19–21]. When the DLSRG iswith running, the follows inductance is inversely proportional toofthe Whenreaches the rotor the DLSRG is running, the inductance is inversely proportional to the reluctance. When the rotor
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the maximum value and the reluctance is the smallest. When the rotor tooth is separated from the center line of the stator tooth by one tooth width, the phase winding inductance reaches the minimum value, and the magnetoresistance reaches the maximum. When running in a single cycle, it is divided into excitation stage and power generation stage. In the excitation stage, the magnetic pull force is in the same direction as the external mechanical force, and the magnetic field energy is stored; in the power generation stage, the magnetic pulling force is opposite to the external mechanical force, which overcomes the work done by the external mechanical force, changes the external mechanical energy into electric energy, and also releases the stored magnetic field energy. 3. Mathematical Modeling The first cycle of DLSRG operation is divided into two stages, excitation stage and generation stage. There is essential difference between DLSRG and traditional generator. DLSRG operates independently in three-phase operation process. Its electromagnetic force equation is as follows: f (i k , x ) =
1 2 dLk i , 2 k dx
k = 1, 2, 3
(1)
where ik is the phase current of phase k; Lk is the self inductance coefficient of the k phase of the generator. This equation shows that the electromagnetic force is related to the square of the current and the rate of change of the self-inductance. When dLk /dx > 0, the transverse magnetic pull force is in the same direction as the external mechanical force, and the generator is in the excitation stage, when dLk /dx < 0, the transverse magnetic pull force is opposite to the external mechanical force, and the generator is in the generation stage. The k phase total flux equation of generator is: ψk = Lk ik ,
k = 1, 2, 3
(2)
where Lk is the k phase inductor; ik is the phase current of phase k. This equation shows that the total flux of phase k is proportional to the inductance of phase k and the current of phase k. The k phase terminal voltage equation of generator is as follows: uk = Rk ik +
dψk , dt
k = 1, 2, 3
(3)
Among them, Rk and ik are generator phase k resistance and current; Ψk is the total flux of k phase of generator. This equation states that the k phase terminal voltage consists of two parts, one part consists of the voltage on the resistance of phase k, the other is the voltage generated by the rate of change of the total flux of phase k. According to the structure and operation characteristics of DLSRG, when the DLSRG is placed vertically, the normal force on the DLSRG actuator is basically zero, and the effect on the generator operation can be neglected in case of neglecting magnetic flux leakage. Therefore, the friction force can be neglected when considering the motion equation of the rotor. The motion equation of the generator rotor is as follows: d2 x F = m 2 ± f ± mg (4) dt where F is the input of mechanical force, m is the mass of the rotor, x is the displacement of the rotor, t is the moving time of the rotor, and f is the electromagnetic force of the generator. When the generator is in the excitation stage, f is in the same direction as the external mechanical force and when the generator enters the generation stage, f is opposite to the external mechanical force. To sum up, the mathematical model of DLSRG is represented by the following equations:
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dψ k , k = 1, 2,3 dt 1 dL f (ik , x) = ik2 k , k = 1, 2,3 dψdx k 2 uk = Rk ik + dt , k = 1, 2, 3 2 k ,fk±=mg1, 2, 3 f (i k , F x )==m 12di2k xdL ± dx 2 2 F = m ddtdt2x ± f ± mg uk = Rk ik +
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(5) (5)
The The three three formulas formulas in in Equation Equation (5) (5) have have been been explained explained in in the the above above article. article. 4. 4. Analysis Analysis of of Electromagnetic Electromagnetic Characteristics Characteristics of of DLSRG DLSRG In In the the transient transient field, field, the moving speed of the rotor is 1 m/s, m/s,the thesimulation simulation time time is is 66 66 ms ms and and the the simulation simulation step step is is 22 ms. ms. The The electromagnetic electromagnetic characteristics characteristics of of DLSRG DLSRG are analyzed. 4.1. Analysis Analysis of of Inductance Inductance Characteristics Characteristics 4.1. Taking the A phase winding winding as as an an example, example, the the current current is is 00 A, A, 22 A, A, 44 A, A, 66 A, A, 88 A, A, 10 10 A, A, winding winding Taking inductance and areare shown in Figure 3. Figure 3a is a phase waveform, inductance andmutual mutualinductance inductance shown in Figure 3. Figure 3a is A a inductance phase A inductance Figure 3b,cFigure is the mutual inductance of A phaseofwinding B phasetowinding A phase waveform, 3b,c is the mutual inductance A phaseto winding B phase and winding and winding A phase to C phase the mutual of phaseof A phase winding to that oftophase B phase winding is about winding to winding, C phase winding, theinductance mutual inductance A winding that of B winding 1.85~8%, and the mutual of phase A about 0.67~4.4% of that of phase A of winding. is about 1.85~8%, and theinductance mutual inductance ofwinding phase Aiswinding is about 0.67~4.4% of that phase From the above calculated it canvalues, be seenitthat proportion mutual inductance toinductance inductance A winding. From the abovevalues, calculated can the be seen that theofproportion of mutual is inductance very small and cansmall be ignored [22,23]. to is very and can be ignored [22,23].
(a)
(b) Figure 3. Cont.
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(c) (c) Figure Figure 3. 3. When When the the winding winding current current is is 00 A, A, 22 A, A, 44 A, A, 66 A, A, 88 A, A, 10 10 A, A, winding winding inductance inductance and and mutual mutual Figure 3. When the winding current isPhase 0 A, 2AA,self-inductance; 4 A, 6 A, 8 A, 10 A,Phase winding inductance and mutual inductance are shown in Figure 3. (a) (b) A-B Mutual Inductance; inductance are shown in Figure 3. (a) Phase A self-inductance; (b) Phase A-B Mutual Inductance;(c) (c) inductance are shown in Figure 3. (a) Phase A self-inductance; (b) Phase A-B Mutual Inductance; (c) Phase Phase A-C A-C Mutual Mutual Inductance. Inductance. Phase A-C Mutual Inductance.
4.2. Analysis Analysis of of Magnetic Magnetic Saturation Saturation 4.2. 4.2. Analysis of Magnetic Saturation The magnetic magnetic density density distribution distribution clouds clouds of of the the typical typical position position of of the the A A phase phase winding winding running running The The magnetic density distribution clouds of the typical position of the A phase winding running at a typical position for one cycle with 10 A excitation current are shown in Figure 4. During the at a typical position for one cycle with During the at a typical position for one cycle with 10 A excitation current are shown in Figure 4. During the operation of of the the generator, generator, the the magnetic magnetic density density of of the the stator stator yoke yoke is is always always higher higher than than that that of of the the operation operation of the generator, the magnetic density of the stator yoke is always higher than that of the tooth, and the maximum magnetic density of the generator stator tooth alignment with the center line tooth, the maximum magnetic density of the generator stator tooth alignment with the center tooth, and thetooth maximum magnetic ofwhich the stator tooth alignment with the center of the is about 17475 GSdensity [24], which is generator lower thanthan the the saturation magnetic density of the line of motor the motor tooth is about 17475 GS [24], is lower saturation magnetic density of line of the motor tooth is about 17475 GS [24], which is lower than the saturation magnetic density of silicon steelsteel sheet. The The magnetic density of excitation stage stage and generation stage is lower of the silicon sheet. magnetic density of excitation and generation stage is than lowerthat than the silicon steel sheet. The magnetic density of excitation stage and generation stage is lower than saturation magnetic density, which can be regarded as a linear model, so DLSRG meets the design that of saturation magnetic density, which can be regarded as a linear model, so DLSRG meets the that of requirements saturation magnetic density, which can be regarded as a linear model, so DLSRG meets the requirements of magnetic saturation. design of magnetic saturation. design requirements of magnetic saturation.
(a) Excitation stage (a) Excitation stage
(b) critical state (b) critical state Figure 4. Cont.
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(c) power generation stage Figure 4. Magnetic Magnetic density distribution cloud image of typical position in one cycle operation of Figure Figure 4. Magnetic density density distribution distribution cloud cloud image image of of typical typical position position in in one one cycle cycle operation operation of of DLSRG. (a) The generator is in the excitation phase; (b) The generator is in the critical state; (c) The DLSRG. DLSRG. (a) (a) The The generator generator is is in in the the excitation excitation phase; phase; (b) (b) The The generator generator is is in in the the critical critical state; state; (c) (c) The The generator is in the power generation stage. generator generator is is in in the the power power generation generation stage.
4.3. Analysis Analysis of of Magnetic Magnetic Pulling Pulling Force Force 4.3. In aa generation generation cycle, cycle, the the position position of of the the right right pole pole tip tip of of the the follower follower tooth tooth aligned aligned with with the the left left In pole tip of the stator tooth, and the alignment position between the center line of the actuator tooth pole tip of the stator tooth, and the alignment position between the center line of the actuator tooth and the the center center line line of of the the stator stator tooth tooth is is called called the the excitation excitation stage, stage, and and the the transverse transverse magnetic magnetic pull pull and force of of the the actuator actuator is is the the same same as as the the direction direction of of the mechanical force. force. In In this this process, process, the the force the external external mechanical generator stores the magnetic field. The position of the center line of the actuator tooth aligned with generator stores the magnetic field. The position of the center line of the actuator tooth aligned with the center center line line of of the the stator stator tooth tooth to to the the position position of of the the left left pole pole tip tip of of the the stator stator tooth tooth and and the the right right the pole tip of the stator tooth is called the power generation stage, and the transverse magnetic pull of pole tip of the stator tooth is called the power generation stage, and the transverse magnetic pull of the actuator is opposite to the direction of the external mechanical force. Transverse magnetic pull the actuator is opposite to the direction of the external mechanical force. Transverse magnetic pull overcomes the the work work done done by by external external mechanical mechanical force. force. The The greater greater the the transverse transverse magnetic magnetic pull pull is, is, overcomes the more work is done to overcome the external mechanical force, thus the efficiency of generator the more work is done to overcome the external mechanical force, thus the efficiency of generator generation can can be be improved. improved. Therefore, Therefore, in in the the process process of of DLSRG DLSRG running, running, the the transverse transverse magnetic magnetic generation pull force force is magnetic pull pull force force changes changes with with the the pull is as as large large as as possible, possible, and and the the tangential tangential transverse transverse magnetic current, as shown in Figure 5, and the transverse magnetic tension force increases with the increase of current, as shown in Figure 5, and the transverse magnetic tension force increases with the increase thethe current. Therefore, the transverse magnetic tensiontension can be increased by increasing the excitation of current. Therefore, the transverse magnetic can be increased by increasing the current properly, and then the generation efficiency can be improved. excitation current properly, and then the generation efficiency can be improved.
Figure 5. 5. When When the the winding winding current current is is 00 A, A, 2 A, A, 44 A, A, 6 A, A, 88 A, A, 10 10 A A, the the transverse transverse magnetic magnetic pull pull force force Figure Figure 5. When the winding current is 0 A, 22 A, 4 A, 66 A, 8 A, 10 A, the transverse magnetic pull force changes with current as shown in Figure 5. changes with with current current as as shown shown in in Figure Figure 5. 5. changes
During the operation of DLSRG, two magnetic pull forces at a certain angle with the moving direction of the actuator are applied to the actuator, which are decomposed into transverse and radial
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two magnetic pull forces at a certain angle with the moving 8 of 17 direction of the actuator are applied to the actuator, which are decomposed into transverse and radial directions. Without Without considering consideringmagnetic magneticflux fluxleakage, leakage,the the two-sided structure is symmetrical two-sided structure is symmetrical andand the the radial magnetic is zero. However, in practice, the change the relative position radial magnetic pullpull forceforce is zero. However, in practice, with with the change of theof relative position of the of the and rotorstator, and stator, therebewill be asymmetric magnetic leakage the air gap. The radial magnetic rotor there will asymmetric magnetic leakage in theinair gap. The radial magnetic pull pull produces fluctuations, and the simulation waveform of the radial magnetic pull is shown produces fluctuations, and the simulation waveform of the radial magnetic pull is shown in Figurein 6. Figure 6.increase With the ofcurrent, excitation theofamplitude of radial increases With the ofincrease excitation the current, amplitude radial magnetic pullmagnetic increases pull exponentially, exponentially, but the radial magnetic is pull pulsation is relatively small, within controllable range. but the radial magnetic pull pulsation relatively small, within controllable range. Moreover, the Moreover, maximum radial pullactuator force of the actuator 293 N, the friction coefficient of maximum the radial magnetic pullmagnetic force of the is 293 N, theis friction coefficient of the linear the linearisbearing is 0.002–0.003 and the maximum friction The friction force haseffect little bearing 0.002–0.003 and the maximum friction force is force 0.879 is N.0.879 The N. friction force has little effect the practical running stability of DLSRG. Therefore, the normal magnetic pull the DLSRG on theon practical running stability of DLSRG. Therefore, the normal magnetic pull of theof DLSRG rotor rotor is negligible. is negligible.
Figure 6. 6. When When the the winding winding current current is is 00 A, A, 22 A, A, 44 A, A, 66 A, A, 88 A, A, 10 10 A, A, the the radial radial magnetic magnetic pull pull force force Figure simulation waveform is shown in Figure 6. simulation waveform is shown in Figure 6.
5. Power Generation Simulation Experiment 5. Power Generation Simulation Experiment Generators are also required to verify continuous generation capacity. Switched reluctance Generators are also required to verify continuous generation capacity. Switched reluctance generator is very special and has many influence factors on power generation, such as turn-on and generator is very special and has many influence factors on power generation, such as turn-on and turn-off position, load characteristic, speed source, excitation voltage. In this section, the influence turn-off position, load characteristic, speed source, excitation voltage. In this section, the influence of of the above factors on generation performance is studied. The penalty coefficient is introduced to the above factors on generation performance is studied. The penalty coefficient is introduced to optimize the opening and closing positions. optimize the opening and closing positions. Ansoft Maxwell and Ansoft Simplorer software are used to carry out the joint simulation Ansoft Maxwell and Ansoft Simplorer software are used to carry out the joint simulation experiment. The DLSRG joint simulation system, as shown in Figure 7, is mainly composed of experiment. The DLSRG joint simulation system, as shown in Figure 7, is mainly composed of excitation power supply, motor module, main circuit and control module. The main circuit adopts excitation power supply, motor module, main circuit and control module. The main circuit adopts asymmetric half-bridge circuit, and the main circuit realizes complete isolation between phase and asymmetric half-bridge circuit, and the main circuit realizes complete isolation between phase and phase. In the main circuit, six IGBT and six diodes D1~D6 are used as the continuous current diodes, phase. In the main circuit, six IGBT and six diodes D1~D6 are used as the continuous current diodes, the load end parallels the filter capacitance C and the excitation power supply end series diode to the load end parallels the filter capacitance C and the excitation power supply end series diode to prevent the current backflow. In a generation cycle, it can be regarded as the excitation circuit and the prevent the current backflow. In a generation cycle, it can be regarded as the excitation circuit and generation circuit. The control unit uses the control module and writes the program in the control the generation circuit. The control unit uses the control module and writes the program in the control module, thus outputs the needed trigger pulse signal. module, thus outputs the needed trigger pulse signal.
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Figure 7. The DLSRG joint simulation system is mainly composed of excitation power supply, motor module, main circuit and control module as shown in Figure 7. composed of of excitation excitation power power supply, supply, motor Figure 7. The DLSRG joint simulation system is mainly composed module, main circuit and control module as shown shown in in Figure Figure 7. 7.
5.1. Analysis of Influencing Factors
5.1. Analysis of Influencing Factors 5.1. of Turn-Off Influencing Factors on Phase Current 5.1.1.Analysis Effect of Position 5.1.1. Effect of Turn-Off Position on Phase Current turn-off positions are on all Phase 49.5 mm. The phase current waveforms at different turn-on 5.1.1.The Effect of Turn-Off Position Current The turn-off positions are all 49.5 the mm.curve The phase waveforms at different turn-on positions positions are shown in Figure 8, and L is a current waveform of inductance in generation cycle. It The turn-off positions are all 49.5 The phase current in waveforms atcycle. different are shown Figure and the curve is amm. waveform inductance It can turn-on beWhen seen can be seeninfrom the 8, diagram that theLphase current isof greatly affected generation by the opening position. positions are shown Figure 8,current and theiscurve L is a waveform of inductance in generation cycle. It fromopening the diagram thatin greatly by theand opening position. the position opening the position isthe 8.5phase mm, the phase currentaffected is the largest, the smaller theWhen opening can be seen from thethe diagram that theisphase currentand is greatly affected by the opening position. When position is 8.5 mm, phase current the largest, the smaller the switched opening position is, the greater is, the greater the phase current is. According to the principle of the reluctance generator, the opening position is 8.5 mm, to thethe phase current the largest, reluctance and the smaller the opening position phase current principle of is the switched generator, the generator is the generator is inis. theAccording electric excitation stage when the inductance rises, and the generator converts is, the greater the phase current is. According to the principle of the switched reluctance generator, in the electric excitation stage when the inductance and the generator converts electric energy the electric energy into the mechanical energy andrises, the magnetic field energy. As a the result, the greater the the electric excitation stage when the inductance rises, and the generator intogenerator the mechanical energy and the magnetic field As a result, greater the currentconverts is an the current isisininan electrically excited state, theenergy. more electricity athe generator consumes; oninthe the electric energy into the mechanical energy and the magnetic field energy. As a result, the greater electrically excited state, moreiselectricity a generator consumes; on less the contrary, the contrary, the smaller the the current in an electrically excited state, the electricitythe is smaller consumed. the current is in an electrically excited state, the more electricity a generator consumes; on the When the output of electricity the generator, the lower electric the excitation current considering is in an electrically excited efficiency state, the less is consumed. Whenthe considering output contrary, the smaller the current is in an electrically excited state, the less electricity is consumed. consumption is,generator, the higherthe thelower efficiency is. When selecting the opening the efficiency of the the electric excitation consumption is,position, the higher thephenomenon efficiency is. When considering the output efficiency of the generator, the lower the electric excitation of excessive current in the electric excitation stage should be avoided, so in the opening When selecting the opening position, the phenomenon of excessive current theminimum electric excitation consumption is, the higher the efficiency is. When selecting the opening position, the phenomenon position is 18.5 stage should bemm. avoided, so the minimum opening position is 18.5 mm. of excessive current in the electric excitation stage should be avoided, so the minimum opening position is 18.5 mm.
Figure 8. The turn-off are all The phase phase current at different Figure 8. The turn-off positions positions are all 49.5 49.5 mm. mm. The current waveforms waveforms at different turn-on turn-on positions 8, it be seen fromfrom the Figure 8 that 8the phase is greatly positions are areshown shownininFigure Figure 8,can it can be seen the Figure that the current phase current is affected greatly Figure 8. The turn-off positions are all 49.5 mm. The phase current waveforms at different turn-on by the opening position. affected by the opening position. positions are shown in Figure 8, it can be seen from the Figure 8 that the phase current is greatly The turn-on position is 16.5 The phase phase current current waveform waveform at at different different turn-off is affected by theposition opening is position. The turn-on 16.5 mm. mm. The turn-off positions positions is
shown in in Figure The curve curve L L is is aa waveform It can can be be seen seen from from shown Figure 9. 9. The waveform of of inductance inductance in in generation generation cycle. cycle. It The turn-on position isspeed 16.5 of mm. Thecurrent phase current waveform at different turn-off positions is the diagram that the rising phase is the same in the rising stage of inductance, that is, the diagram that the rising speed of phase current is the same in the rising stage of inductance, that shown in Figure curve L is ahas waveform ofoninductance inofgeneration cycle. It canstage, be stage, seen from thethe magnitude of9.turn-off position no no effect the current the electric excitation and the is, magnitude ofThe turn-off position has effect on the current of the electric excitation and the diagram that the rising speed of phase current is the same in the rising stage of inductance, that is, the magnitude of turn-off position has no effect on the current of the electric excitation stage, and
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change of phase current is obvious in thein phase of inductance descending. That is,That the turn-off position the change of phase current is obvious the phase of inductance descending. is, the turn-off has a great influence on the current in the generation stage. At the stage of inductance descent, the position has a great influence on the current in the generation stage. At the stage of inductance generatorthe converts mechanical and magnetic fieldmagnetic energy into electric energy, and theenergy, higher descent, generator convertsenergy mechanical energy and field energy into electric the phase current the higher efficiency of generator is.ofTherefore, maximum and the higher theis, phase currentthe is, conversion the higher the conversion efficiency generatorthe is. Therefore, current in the generation be ensured when the selected. be seen the maximum current instage the should generation stage should beturn-off ensuredposition when is the turn-offIt can position is from the Itdiagram that the phase current in thethe generation phase in increases with thephase increase of the selected. can be seen from the diagram that phase current the generation increases turn-off position,ofand phaseposition, current and waveform is basically the same when the turn-off position with the increase thethe turn-off the phase current waveform is basically the same when is 47.5 mm and 49.5 is mm, the49.5 phase current is the nearly saturated thesaturated turn-off position is the turn-off position 47.5that mmis,and mm, that is, phase current when is nearly when the 47.5 mm. With the increasing of the position, the change of phase currentofisphase small,current so the turn-off position is 47.5 mm. With the turn-off increasing of the turn-off position, the change turn-off shouldposition be moreshould than 47.5 mm. than 47.5 mm. is small, position so the turn-off be more
Figure 9. 9. The Theturn-on turn-onposition positionisis16.5 16.5mm. mm.The Thephase phasecurrent currentwaveform waveformat atdifferent differentturn-off turn-off positions positions Figure is shown in Figure 9, it can be seen from the Figure 9 that the turn-off position has a great influence on is shown in Figure 9, it can be seen from the Figure 9 that the turn-off position has a great influence thethe current in the generation stage. on current in the generation stage.
5.1.2. Effect of Load on Phase Current 5.1.2. Effect of Load on Phase Current The excitation voltage is 100 V, the moving speed of the rotor is 1 m/s, the simulation time is The excitation voltage is 100 V, the moving speed of the rotor is 1 m/s, the simulation time is 100 100 ms, the simulation step is 2 ms, the open position is 18.5 mm, the turn-off position is 49.5 mm, and ms, the simulation step is 2 ms, the open position is 18.5 mm, the turn-off position is 49.5 mm, and the effect of load on phase current is studied. The waveform of phase current under different loads is the effect of load on phase current is studied. The waveform of phase current under different loads shown in Figure 10. It can be seen from the diagram that the size of the load has great influence on the is shown in Figure 10. It can be seen from the diagram that the size of the load has great influence on phase current at the stage of power generation, when the load value is small (3 Ω), the phase current the phase current at the stage of power generation, when the load value is small (3 Ω), the phase can continue to rise at the beginning of the generation phase for a period of time. When the load value current can continue to rise at the beginning of the generation phase for a period of time. When the is larger, the energy consumed by the load is larger (30 Ω), and the phase current will decrease rapidly load value is larger, the energy consumed by the load is larger (30 Ω), and the phase current will at the beginning of the generation. Choosing different loads has certain influence on the phase current. decrease rapidly at the beginning of the generation. Choosing different loads has certain influence on For the DLSRG studied in this paper, the load resistance is 10 Ω in the simulation experiment. the phase current. For the DLSRG studied in this paper, the load resistance is 10 Ω in the simulation experiment. 5.1.3. Effect of Velocity on Phase Current speedon ofPhase generator rotor is stable or not will seriously affect the stable operation of 5.1.3.Whether Effect of the Velocity Current power generation system. The load R = 10 Ω, excitation voltage U1 is 100 V, simulation time is 100 ms, Whether the speed of generator rotor is stable or not will seriously affect the stable operation of step size is 2 ms, and the phase current waveform at different speeds is shown in Figure 11. It can be power generation system. The load R = 10 Ω, excitation voltage U1 is 100 V, simulation time is 100 seen from the diagram that the phase current decreases with the increase of velocity. When the speed ms, step size is 2 ms, and the phase current waveform at different speeds is shown in Figure 11. It can is too low, the phase current will peak. When the velocity is 0.5 m/s, the current reaches 10 A, and the be seen from the diagram that the phase current decreases with the increase of velocity. When the high peak current will damage the switch. The stable operation of the system is seriously affected, so speed is too low, the phase current will peak. When the velocity is 0.5 m/s, the current reaches 10 A, the phenomenon of too low speed should be avoided when the system is running. and the high peak current will damage the switch. The stable operation of the system is seriously affected, so the phenomenon of too low speed should be avoided when the system is running.
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Figure 10. The phase current waveform under different loads is shown in Figure 10. Choosing Figure 10. waveform under different loadsloads is shown in Figure Choosing different Figure 10. The Thephase phasecurrent current waveform under different is shown in 10. Figure 10. Choosing different loads has certain influence on the phase current. loads has certain influence on the phase current. different loads has certain influence on the phase current.
Figure 11. 11. The The phase phase current current waveform waveform at at different different speeds speeds is is shown shown in in Figure Figure 11. 11. When When the the speed speed is is Figure Figure 11. The phase current waveform at different speeds is shown in Figure 11. When the speed is too low, the phase current will peak. too low, the phase current will peak. too low, the phase current will peak.
5.1.4. Influence Analysis of Bus Voltage 5.1.4. Influence Analysis of Bus Voltage 5.1.4.The Influence Analysis Bus Voltage phase current at of different voltage levels is shown in Figure 12. It can be seen from the diagram The phase current at different voltage levels is shown in Figure 12. It can be seen from the that when the excitation voltage is of the levels rated voltage (50in V),Figure the phase slowly, The phase current at differenthalf voltage is shown 12. Itcurrent can beincreases seen from the diagram that when the excitation voltage is half of the rated voltage (50 V), the phase current increases the amplitude of the current is small, and is rated difficult to meet preset requirement, which diagram that when thephase excitation voltage is half ofitthe voltage (50 the V), the phase current increases slowly, the amplitude of the phase current is small, and it is difficult to meet the preset requirement, results in the generatorofnot the preset generation the starting current slowly, the amplitude thereaching phase current is small, and itperformance. is difficult to However, meet the preset requirement, which results in the generator not reaching the preset generation performance. However, the starting of DLSRG is prevented from being too large when starting, so low voltage can be used to start the which results in the generator not reaching the preset generation performance. However, the starting current of DLSRG is prevented from being too large when starting, so low voltage can be used to start DLSRG.ofWhen theisexcitation voltage exceeds rated voltage, theso phase quickly exceed current DLSRG prevented from being toothe large when starting, low current voltage will can be used to start the DLSRG. When the excitation voltage exceeds the rated voltage, the phase current will quickly the DLSRG. maximum withstanding current of the winding, which will cause great damage to the motor When the excitation voltage exceeds the rated voltage, the phase current will quickly exceed the maximum withstanding current of the winding, which will cause great damage to the winding, and the peak current will easily damage thewinding, switch tube, andwill at the samegreat time,damage the coreto of the the exceed the maximum withstanding current of the which cause motor winding, and the peak current will easily damage the switch tube, and at the same time, the will reachand magnetic saturation. selecting DLSRG excitation power supply, motor winding, the peak current Therefore, will easily when damage the switch tube, and at the same time, the core of the motor will reach magnetic saturation. Therefore, when selecting DLSRG excitation power voltage value should exceed the rated voltage,Therefore, but it should notselecting be too low. The excitation core of the motor willnot reach magnetic saturation. when DLSRG excitationvoltage power supply, the voltage value should not exceed the rated voltage, but it should not be too low. The is chosenthe as voltage 100 V in value the simulation experiment. supply, should not exceed the rated voltage, but it should not be too low. The excitation voltage is chosen as 100 V in the simulation experiment. excitation voltage is chosen as 100 V in the simulation experiment.
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Figure 12. The phase currents at different voltage levels is shown in Figure 12.
5.2. Optimization of Results Figure 12. The The phase phase currents currents at at different different voltage voltage levels levels is is shown shown in in Figure Figure 12. 12. Figure 12. The flow current in the winding can reflect the energy flow of DLSRG in operation, but it can 5.2. Optimization of Results 5.2. of Results not Optimization reflect the effect of turn-on/turn-off position on the efficiency of generator. Therefore, in order to The flow current in the winding can reflect the energy flow of DLSRG in operation, but it can reflect effect of generation, find out optimal turn-off position of a in group of generators to Thethe flow current in the winding can the reflect the energy flow of DLSRG operation, but it can not reflect the effect of turn-on/turn-off position on the efficiency of generator. Therefore, in order to ensure the maximum generation efficiency. The penalty coefficient, that is, the ratio of excitation not reflect the effect of turn-on/turn-off position on the efficiency of generator. Therefore, in order to reflect of generation, outexpressed the optimal position of a group of generators to ensure currentthe to effect generation current, find can be as:turn-off reflect the effect of generation, find out the optimal turn-off position of a group of generators to the maximum generation efficiency. The penalty coefficient, that is, the ratio of excitation current to ensure the maximum generation efficiency. The penalty coefficient, that is, the ratio of excitation I generation current, can be expressed as: current to generation current, can be expressed ε =as:Iinin((avav)) (6) ε = I out ( av ) (6) IIout av)) in ((av ε = current in excitation stage and Iout(av) is the average (6) Iin(av) is the average value of winding phase Iin(av) is the average value of winding phase current I out ( av ) in excitation stage and Iout (av) is the average value of generation current between turn-off position and next turn-on position. According to the value of generation current between turn-off position and next turn-on position. According to the above above formula, the higher the penalty is, the lower the stage generation efficiency will be. Iin(av) is the average value of windingcoefficient current excitation and is the average formula, the higher the penalty coefficient is,phase the lower the in generation efficiency willIout(av) be. Therefore, a set Therefore, a set of optimal opening and closing positions can be found through the penalty value of generation current between turn-off position and next turn-on position. According to the of optimal opening and closing positions can be found through the penalty coefficient. The distribution coefficient. The distribution of penalty coefficients isis,shown in Figure 13. above formula, the higher the penalty coefficient the lower the generation efficiency will be. of penalty coefficients is shown in Figure 13. Therefore, a set of optimal opening and closing positions can be found through the penalty coefficient. The distribution of penalty coefficients is shown in Figure 13.
Figure 13. Distribution of penalty coefficient. Figure 13. Distribution of penalty coefficient.
The penalty coefficient of the load current obtained from the Formula (6) and Figure 13 is The penalty coefficient of the load current obtained from the Formula (6) and Figure 13 is as as follows: Figure 13. Distribution of penalty coefficient. Iav(ab) follows: ε1 = (7) I I av ( abobtained The penalty coefficient of the load current from the Formula (6) and Figure 13 is as ) av(bc) ε1 = (7) follows:
ε1 =
I av (bc ) I av ( ab ) I av (bc )
(7)
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5.2.1. Open Location Optimization 5.2.1. Open Open Location Location Optimization Optimization 5.2.1. The distribution of the optimal penalty coefficient in the open location is shown in Figure 14. The distribution distribution of of the the optimal optimal penalty penalty coefficient coefficient in in the the open open location location is is shown shown in in Figure Figure 14. 14. The TheThe larger thethe opening position is,is,the smaller the penalty coefficient is. When the opening position is larger opening position the smaller the penalty coefficient is. When the opening position The larger the opening position is, the smaller the penalty coefficient is. When the opening position 18.5 the penalty coefficient is the smallest. According to the definition of of penalty coefficient, is mm, 18.5 mm, mm, the penalty penalty coefficient is the the smallest. According to the the definition penalty coefficient,the is 18.5 the coefficient is smallest. According to definition of penalty coefficient, smaller the penalty coefficient is, the better the generation effect is, and the smaller the phase current the smaller smaller the the penalty penalty coefficient coefficient is, is, the the better better the the generation generation effect effect is, is, and and the the smaller smaller the the phase phase the in the excitation stage is, which ensures that the generation effect and current are within the available current in in the the excitation excitation stage stage is, is, which which ensures ensures that that the the generation generation effect effect and and current current are are within within the the current range. It is also necessary to necessary ensure thetoefficiency of mechanical conversion. Therefore, when selecting available range. It is also ensure the efficiency of mechanical conversion. Therefore, available range. It is also necessary to ensure the efficiency of mechanical conversion. Therefore, thewhen opening position, choose xposition, = 18.5 mm as the best opening selecting the opening opening choose 18.5 mm mm as the theposition. best opening opening position. position. when selecting the position, choose xx == 18.5 as best
Figure 14.14. The distribution ofofthe Figure The distribution theoptimal optimalpenalty penaltycoefficient coefficientinin inthe theopen openlocation locationis isshown shownin inFigure Figure 14. Figure 14. The distribution of the optimal penalty coefficient the open location is shown in Figure The larger the opening position is, the smaller the penalty coefficient is. is. 14. The larger the opening position is, the smaller the penalty coefficient 14. The larger the opening position is, the smaller the penalty coefficient is.
5.2.2. Turn OffOff Position 5.2.2. Turn PositionOptimization Optimization 5.2.2. Turn Off Position Optimization Penalty coefficients are shown shown in inFigure Figure15. 15.ByBydefinition, definition, Penalty coefficientsfor fordifferent differentturn-off turn-off locations locations are are thethe Penalty coefficients for different turn-off locations shown in Figure 15. By definition, the smaller the penalty coefficient, the higher the generation efficiency. It can be seen from the diagram smaller the the penalty penalty coefficient, coefficient, the the higher higher the the generation generation efficiency. efficiency. It It can can be be seen seen from from the the diagram diagram smaller that thethe penalty coefficient isisthe smallest when the turn-off positionisis37.5 37.5mm, mm,and andthe the maximum that penalty coefficient the smallest when the turn-off position maximum that the penalty coefficient is the smallest when the turn-off position is 37.5 mm, and the maximum punishment coefficient isiswhen the turn-off position 49.5 mm. mm. But Butwhen whenconsidering considering the penalty punishment coefficient when the turn-off position is 49.5 the penalty punishment coefficient is when the turn-off position is 49.5 mm. But when considering the penalty coefficient, the optimal turn-off position is 37.5 mm. However, the mechanical conversion efficiency coefficient, the the optimal optimal turn-off turn-off position position is is 37.5 37.5 mm. mm. However, However, the the mechanical mechanical conversion conversion efficiency efficiency coefficient, should also be taken into account when the penalty coefficient is considered. From Figure 9, we wewe cancan should also be taken into account when the penalty coefficient is considered. From Figure 9, should also be taken into account when the penalty coefficient is considered. From Figure 9, can see that the mechanical conversion efficiency the highest when the turn-off position is 49.5 mm. seesee that the mechanical conversion efficiency is the highest when the turn-off position is 49.5 mm. that the mechanical conversion efficiency is the highest when the turn-off position is 49.5 mm. The final optimal closing position was 49.5 mm. The final optimal The final optimalclosing closingposition positionwas was49.5 49.5 mm. mm.
Figure 15.The The distribution distribution of ofofthe the optimal penalty coefficient in the thein turn-off locationlocation is shown shownisin inshown Figure in Figure 15. distribution the optimal penalty coefficient the turn-off Figure 15. The optimal penalty coefficient in turn-off location is Figure 15. The larger the turn-off position is, the larger the penalty coefficient is. Figure 15.larger The larger the turn-off position is, thethe larger the penalty coefficient is. 15. The the turn-off position is, the larger penalty coefficient is.
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5.3. Analysis of Simulation Results of Three-Phase Generation 5.3. Analysis of Simulation Results of Three-Phase Generation 5.3. Analysis of Simulation Results of Three-Phase Generation 5.3.1. Power Analysis 5.3.1. Power Analysis 5.3.1. Power Analysis After DLSRG is simulated, the efficiency of DLSRG can be estimated by estimating the energy After DLSRG is simulated, the efficiency of DLSRG can be estimated by estimating the energy After in DLSRG is simulated, the of efficiency of DLSRG canthe be estimated by estimating energy absorbed the excitation phase a generation cycle, electrical energy outputthe from the absorbed in the excitation phase of a generation cycle, the electrical energy output from the absorbed in phase the excitation of a generation electrical energyIfoutput fromelectric the generation generation and thephase mechanical energy cycle, input the from the outside. the total energy generation phase and the mechanical energy input from the outside. If the total electric energy phase andinthe energy from the totalenergy electricoutput energyinabsorbed in the absorbed themechanical excitation phase is input recorded asthe W1,outside. the totalIfelectrical the generation absorbed in the excitation phase is recorded as W1, the total electrical energy output in the generation excitation phase is as recorded asthe W 1 ,mechanical the total electrical output inexternal the generation phase is recorded phase is recorded W2, and energyenergy input from the input of the generating phase is recorded as W2, and the mechanical energy input from the external input of the generating as W 2 ,isand the mechanical energy input efficiency from the external input the generating is recorded as phase recorded as W3, the generation of DLSRG canofbe expressed, asphase follows: phase is recorded as W3, the generation efficiency of DLSRG can be expressed, as follows: W 3 , the generation efficiency of DLSRG can beWexpressed, as follows: −W η = W22 − W11 × 100% (8) W × 100% η= 3 (8) W2 − W3W1 η= × 100% (8) W3 power waveform of DLSRG, Figure 17 shows the Figure 16 shows the three-phase generation Figure 16 shows the three-phase generation power waveform of DLSRG, Figure 17 shows the excitation power of the DLSRG excitation phase, and Figure 18 shows the force waveform of the Figurepower 16 shows theDLSRG three-phase generation waveform of DLSRG, Figure 17 shows excitation of the excitation phase,power and Figure 18 shows the force waveform of the generator in the generation phase. According to Formula (8), the electric energy absorbed in the excitation in power of the DLSRG excitation phase, and Figure shows theenergy force waveform of the generator the generation phase. According to Formula (8),18the electric absorbed in excitation phase, the electric energy emitted during the generation phase, and the mechanical energy generator in the generation phase. According Formula the electric energy absorbed in the excitation excitation phase, the electric energy emittedto during the(8), generation phase, and the mechanical energy absorbed are estimated. Furthermore, the generation efficiency of DLSRG can be estimated. The phase, the are electric energy emitted during the the generation and the mechanical absorbedThe are absorbed estimated. Furthermore, generationphase, efficiency of DLSRG canenergy be estimated. generation efficiency of DLSRG can be estimated to be about 80.6% by using the equivalent area estimated. Furthermore, generation efficiency of DLSRG can be80.6% estimated. The generation efficiency generation efficiency ofthe DLSRG can be estimated to be about by using the equivalent area method. of DLSRG can be estimated to be about 80.6% by using the equivalent area method. method.
Figure 16. Three-phase Generation Power Waveform of DLSRG. Figure 16. 16. Three-phase Three-phase Generation Generation Power Power Waveform Waveform of Figure of DLSRG. DLSRG.
Figure 17. Excitation Excitation Power in DLSRG excitation stage. Figure 17. Excitation Power in DLSRG excitation stage.
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Figure 18. The force waveform of the rotor in power generation stage. Figure 18. 18. The The force force waveform waveform of of the the rotor rotor in in power power generation generation stage. Figure stage.
5.3.2. Analysis 5.3.2. Generation Generation Voltage Voltage Analysis 5.3.2. Generation Voltage Analysis Taking the excitation excitation voltage voltage 100 and adopting adopting the fixed turn-on turn-on turn-off turn-off position position control Taking the 100 V V and the fixed control Taking the excitation voltage 100 Vposition and adopting the fixed turn-on turn-off position control method, the optimal turn-on/turn-off is selected to simulate the three-phase power method, the optimal turn-on/turn-off position is selected to simulate the three-phase power generation. method, the optimal turn-on/turn-off position is selected to simulate the three-phase power generation. The voltage generation voltage waveform shown19. in Figure It canfrom be seen the diagram The generation waveform is shown inis Figure It can 19. be seen the from diagram that the generation. The generation waveform is shown in Figure 19.the It can be seenoutput from the diagram that the generation voltagevoltage waveform make generator stable, the generation voltage waveform is large. isInlarge. orderIntoorder maketothe generator output stable, the filtered that thecapacitor generation voltage waveform is at large. In order to make thegeneration generator voltage output stable, the filtered of 1800 uF is connected the load end. The filtered waveform capacitor of 1800 uF is connected at the load end. The filtered generation voltage waveform is shown in filtered capacitor of 20. 1800 uFgeneration is connected at theincreases load end. The filtered generation voltage waveform is shown Figure The voltage to 80time, V atand the the initial time, and the Figure 20. in The generation voltage increases rapidly to 80 V rapidly at the initial voltage decreases is shown in Figure 20. 0.3 Thes due generation voltageof increases rapidly toAfter 80 V0.5 at s, the initial time, and the voltage decreases after to the addition filter capacitance. the generation voltage after 0.3 s due to the addition of filter capacitance. After 0.5 s, the generation voltage is basically stable voltage decreases after 0.3 s due to the addition of filter capacitance. After 0.5 s, the generation voltage is stable at 62 V. at basically 62 V. is basically stable at 62 V.
Figure 19. When there there is is no no filter filter capacitor, capacitor, the the power generation voltage voltage waveform waveform is is shown shown in in Figure 19. When power generation Figure 19. 19. When there is no filter capacitor, the power generation voltage waveform is shown in Figure 19. Figure 19.
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Figure 20. The The filtered filtered capacitor capacitor of of 1800 1800 uF uF is is connected connected at at the the load load end, end, the the filtered filtered generation generation voltage voltage Figure 20. waveform is shown in Figure 20. waveform is shown in Figure 20.
6. Conclusions 6. Conclusions In this paper, a double-sided linear switched reluctance generator for wave energy conversion In this paper, a double-sided linear switched reluctance generator for wave energy conversion is designed. The structure of the generator, the structural dimensions of the stator and the rotor is designed. The structure of the generator, the structural dimensions of the stator and the rotor and and the package mode of the windings are determined, and the mathematical model of DLSRG is the package mode of the windings are determined, and the mathematical model of DLSRG is established. The finite element analysis method is used to analyze the electromagnetic characteristics established. The finite element analysis method is used to analyze the electromagnetic characteristics of the bilateral linear switched reluctance generator, and the combined power generation simulation of the bilateral linear switched reluctance generator, and the combined power generation simulation system is established to analyze the power generation characteristics of the bilateral linear switched system is established to analyze the power generation characteristics of the bilateral linear switched reluctance generator. The simulation results show that the fluctuation of magnetic pull force is almost reluctance generator. The simulation results show that the fluctuation of magnetic pull force is almost zero, the mutual inductance of phase winding accounts for about 0.67% of the inductance of phase zero, the mutual inductance of phase winding accounts for about 0.67% of the inductance of phase winding, which is negligible, and the magnetic field characteristic accords with the design requirement winding, which is negligible, and the magnetic field characteristic accords with the design of motor, the filtered generation voltage tends to be stable after 0.5 s, and the stable output of 62 V, requirement of motor, the filtered generation voltage tends to be stable after 0.5 s, and the stable the efficiency of generating electricity is as high as 80.6%, and it has the ability to generate electricity output of 62 V, the efficiency of generating electricity is as high as 80.6%, and it has the ability to continuously, which meets the design requirements. The research work in this paper provides a generate electricity continuously, which meets the design requirements. The research work in this reference for the research of direct drive wave power generation. paper provides a reference for the research of direct drive wave power generation. Author Contributions: Conceptualization and writing—original draft: Y.C.; investigation: M.C.; methodology and validation: C.M.; software: Z.F. Author Contributions: Conceptualization and writing—original draft: Y.C.; investigation: M.C.; methodology and validation: C.M.; software: Z.F. Funding: This research is supported by the Natural Science Foundation of Shanxi Province (201701D121127) and by the National NaturalisScience Foundation ProjectScience (41776199). Funding: This research supported by the Natural Foundation of Shanxi Province (201701D121127) and Acknowledgments: Yinke Dou provided valuable advice on the study idea, design and write-up. Thanks also go by the National Natural Science Foundation Project (41776199). to Wentao Wu, Xiangnan Hou, Zaihe Shen, Yanzhao Hao for their assistance during the research. Acknowledgments: Yinke Dou provided valuable advice on the study idea, design and write-up. Thanks also Conflicts of Interest: The authors no conflict of interest. founding sponsors role in the design go to Wentao Wu, Xiangnan Hou,declare Zaihe Shen, Yanzhao Hao forThe their assistance duringhad the no research. of the study; in the collection, analyses, or interpretation of data; in the writing of the manuscript, and in the decision theThe results. Conflictstoofpublish Interest: authors declare no conflict of interest. The founding sponsors had no role in the design of the study; in the collection, analyses, or interpretation of data; in the writing of the manuscript, and in the References decision to publish the results. 1.
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