14th International Power Electronics and Motion Control Conference, EPE-PEMC 2010
A Toolbox to Design and Study Electric Drives Valery Vodovozov, Zoja Raud and Mikhail Egorov Tallinn University of Technology, Tallinn, Estonia, e-mail:
[email protected] Abstract—The paper introduces an effective toolbox for engineers, researchers and students to design and study electric drives. The described package eDrive includes a database of motors, power converters, and gears, an objectoriented simulator, a virtual signal generator, the module of the torque/current, speed, and path controllers, as well as the suitable visual interface. The system provides for the development, tuning, and investigation of electric drives with current, speed, and position adjustment in the openloop and closed-loop modes of operation. Keywords—electric drive, design, simulation, modelling, software.
I. INTRODUCTION eDrive toolbox contains software for the development and investigation of electric drives. Due to its strong orientation to driving applications, this toolbox has advantages over other programs for power users and students. To compute, choose, and tune driving equipment, some well-known companies have developed their own technologies. Examples are the guides and software of ABB, Siemens, Omron, Sew Eurodrive, Maxon Motors, Mitsubishi [1], [2], [3]. The cores of their toolboxes are composed on the preliminary worked-out corporative databases, the management systems of which help to choose and optimize multiple electric drive combinations. Also, the systems designed are tuned in accordance with the corporative methods. Such approach is conventional for the majority of firms that carry out project designs and have rich experience in decision making based on extensive computer databases, coming up to numerous catalogue archives and "absorbing" their contents and structures [4], [5]. However, their main drawback is the technological restriction and data limiting within the particular corporative scope that deprive a designer of an optimum way in the project. It is especially important at the beginning of any project work, when the most responsible decisions are taken. As distinct from the companies which promote and propagate their products, this paper describes an approach addressed to the overall equipment selection, tuning, and optimization independent of the company interests. The paper proposes toolbox availability in the following fields: • simulation of the systems and components of the three-phase induction drives, synchronous servo drives, and dc drives; • automatic selection of motors, converters, and gears as part of the design process; • analysis of the steady-state and transient modes of drives with open-ended and closed-
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• • •
loop control systems supplied from the mains and power converters; exploring how parameters, disturbances, and references affect the drive performance; drive tuning and parameter optimization; generation of reports about the drive composition and operation.
II. OBJECT-ORIENTED TOPOLOGY A model is the main component of the development, study, and maintenance procedures, as well as the heart of the software. It is of major importance that an effective model should involve some structural and information redundancy to be taken into account in the future progress of the simulating object [6], [7]. The most popular kinds of software are the toolboxes that operate in a uniform simulation environment. Among them, use is made of such widespread tools as MatLab and Simulink from MathWorks, PSIM of PowerSys, LabVIEW, Electronics Workbench and Multisim of National Instruments, Spice from OrCad, and Vissim of Visual Solution. Most of them suit for the design and research of automation systems or their components. The main advantages of the mentioned systems are their powerful mathematics, high quality of tables, graphics, and computing data presentations, interconnection with hardware and operation systems, and comfortable adaptation to computers of different styles and productivity. In turn, eDrive features high compactness, efficiency, and convenience for specialists in motor drives who have low experience in modelling and programming. This interdependent tool requires no additional simulation software or problematic interfaces with the drive components, testing equipment, or real-time devices. The software provides for simulation and computation, testing and result verification, drive tuning and optimization. The toolbox described is the real example of an objectoriented technology [8], [9] that integrates a great variety of models. Here, the general description of an electrical machine plays the role of the model core for electrical motors of different types. By analogy, the general discrete converter description was used as the model core of power converters. In the load model, efforts have been directed towards choosing and linking the traditional models of gears, couplings, and transmissions. The developed class library complies with ANSI standards and contains five basic classes: • electrical motors, • power electronic converters, • mechanical gears and loads, • controllers, • signals.
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The Motor class combines the data members that keep information about the calculating points, the model time steps, and elastic deformation of the mechanical part of the system. It includes a set of functions that represent the common two-phase electrical motor model [10], the variables of which are stator and rotor phase currents, electromagnetic torques, and rotation speeds of the rotor field and loading shaft. Some variables of the Motor class describe the type of supply and load, the motor pole number, phase number, inductance and resistance, the moment of inertia, electromechanical and electromagnetic factors. An additional member-function list includes the motor parameter functions that implement the procedure for solving the differential equations. Each of the model elements may interact with other members via the public functions that deliver results into the file or onto the display screen. A model of a dc motor with an excitation circuit has been inherited from the Motor class. Its members control the data input for the computation process. Other inherited classes belonging to a dc motor with permanent magnets, a squirrel-cage induction motor and a synchronous motor have the same structure. The next basic class, Trans, describes the power supplies of different kinds to run the machines of the Motor class. The Motor has been announced as a friend class for Trans, so it has an access into the private area of Trans. The Trans class encapsulates the variables that describe the type of power supply and some methods. They supervise the choice of an appropriate power source and describe the three-phase and dc supply mains with their inductance and resistance. Some polymorphous functions reflect the nature of a thyristor and transistor converters. The variables of the Trans class collect information about the frequency, voltage, resistance, and inductance of the power converters providing for the class interaction with other eDrive modules. The Loads class combines the models of the mechanisms of different kinds. Its main area encloses such data members as the load type and torque, elastic and tough factors, etc. The dispatch functions simulate constant and time-change loads. The public area of this class includes the moment of inertia and gear description. The Motor class is labelled as a friend of Loads. A user of eDrive works with the main module Model and with the linked modules Result, Report, Database, Options, and Help. There are some additional modules that represent the model data and other auxiliary information. The main document of eDrive is a model of electric drive, which includes the motor data and usually carries information concerning the power electronic converter, load, controller, and signals. Model properties occupy the fields of the five tabs in the main Model window − Motor, Supply, Load, Controller, and Signals (Fig. 1). A new model is created by filling in the required tabs of the window. A model may be saved using the text format such that a user can prepare and edit it by a text editor as well as by the built-in editor of the toolbox. The special tools serve to test a model with or without converters, loads, controllers, and references. Overall information about the motor is presented on the Motor tab of the model interface. It informs about the motor class and type − induction machine (ma), DC motor (md), or synchronous servomotor (ms). Winding data include Active resistance and Inductance or
Reactance and Mutual (Exciting) inductance. The model is sufficiently universal, allowing for some missing winding data to be calculated automatically. Mechanical data involve Power, Speed, Moment of inertia, Torque, Maximum torque, and Stall torque. By analogy, such data are processed as Voltage, Current, and Starting current. They keep the rated values of the stator or rotor dependent on the motor class. In the case of their absence or nulls, the program calculates or assumes the most probable rated and starting values and presents them on the Analysis tab of the Result module and in the report. The data of the motor power supply occupy the Supply tab of the program interface. Here, the source of the supply is indicated − the mains, a transistor converter (ca, cd, cs), or a thyristor converter (cat, cdt, cst). Input data describe Active resistances and Inductances of the circuits that supply the motor stator and rotor. The main output data of the power supply are Frequency and Voltage that feed the motor. While these data are missing, the rated motor data are used during the simulation of the work upon the mains supply. To simulate the adjustable drive, the rated converter values should be given in these fields. In the case of shunt-wound dc motors with excitation winding, the Excitation voltage is required additionally. Among the converter rated values, there are such data as Current, Ripples, output Power, Delay, and Maximum input voltage of a converter. Asynchronous motors may be supplied from the mains, from the thyristor cycloconverters, or from the transistor power converters. The feeding variants of the dc motors include the dc mains, the thyristor rectifiers, or the transistor converters. As a rule, servomotors may be fed by the specific transistor converters that perform the signals of the rotor position sensor built in the servomotor. When the synchronous step motors are the objects of choice, the step motor drivers should be used as the supply source. Information about the mechanical units of the electric drive occupies the Load tab of the program interface. Here, the category of a gear may be selected − the spur gear (gt), the worm gear (gw), the ball screw gear (gs), or the planetary gear (gp). The necessary fields of the interface are filled with gear data − Type, Ratio, output Torque, Power and input Speed, Gap, and Efficiency. The load data are referred to the motor shaft automatically. When such information is missing, calculated data are used in the model. Important data of a mechanism are the Moment of inertia and Counter-torque. While such data are missing, the no-load mode is simulated. The mechanism is ranked as rigid while the Elastic Transmission parameter is not indicated. Otherwise, Rigidity and Elastic friction are taken into account in the simulation process. Thanks to the Active load mode, the constant sign of the torque may be taken into account when a mechanism is going into reverse that is typical of hoists. The Controller tab of the model interface is intended to tune an adjustable motor drive and to design the closedloop systems. The toolbox is suitable to develop the standard regulators − the current regulator (I-regulator), the speed regulator (w-regulator), and the path regulator (f-regulator). One may arrange a cascade regulator connection, which in turn affects Supply, Motor and Load. Each regulator has its Gain, Integral time constant, Differential time constant, and output Signal restriction. Negative feedbacks link the current sensor (I-sensor), the
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Fig. 2. Signal generator window
Fig. 1. Main Model window
speed sensor (w-sensor), and the path sensor (f-sensor) having the Gains and the smoothing Filter time constants. While the sensor gain is not defined, the openended non-adjustable loop is simulated. An effective Auto-tuning mode provides adaptive tuning of the controllers. To compensate a speed error, the loop of predetermined reference Feedforward is provided. Normally it is used instead of the path loop integrator. III. SIGNAL GENERATION The powerful signal generator of eDrive is destined for the required speed and path setting, the reference and disturbance generating for the simulated electric drives, examining the influence of distortions and disturbances upon the behavior of the drive components, the signal time and level offsets, and the filters and correctors selection to improve the system performance (Fig. 2). The generator contains the following: • Signal module that represents different sources of references and disturbances, • Offset module that sets the time and level offsets to the transmission path of a signal selected in the previous group, • Correction module that simulates digital conversion of a signal selected in a previous group in accordance with the proposed transfer function, • Chart module that represents the input and output signals of all the above mentioned modules. The generator produces the references and disturbances. When the Reference mode is selected, the setpoint speed is multiplied by the instant Signal value. As a result, the input reference may alternate with time in various fashions. Conversely, when the Disturbance mode is selected, the Load counter-torque is referred to Signal. As a result, the load may alternate with time in various fashions. The maximum angle rotation of the output shaft may be indicated when the controller has the path loop. The signal generator includes the models of the signals − Step signal, Rect signal with of a referred rectangle continuation, Ramp and Smooth signals, growing up from 0 to the required level with an adjusted slope, Repeated Pulse, Meander, Triangle, Sine, and Random signals having a given period. Additionally, a designer may utilize the scaled simulation result (model output) as an input signal using the Import mode. The
program receives the speed or current (torque) curve depending on a sub-mode selected in the Import group. To simulate the signal offset, the specific Offset group of controls is arranged. The chosen signal passes through this group without offset (No), with a Delay (gap, lag), with a Clearance (friction, hysteresis), or with a Threshold (level offset). An offset value is referred in milliseconds (time offsets) or in rad/s (threshold). The third group of controls simulates different linear filters and correcting circuits. Here, a signal from the previous group passes via one of the following units: • Amplifier, • Low-pass filter with two gains and two time constants − differential and integral, • High-pass filter with a gain and two time constants − differential and integral, • Band-pass filter with the same properties and additional 2-power integrator, • Band-stop filter with two gains, 1- and 2power integrators and 1- and 2-power differentiators, • I circuit with a gain and integral time constant, • PI circuit with the same properties and additional differential time constant, • D circuit with the differential time constant, • PD circuit with a gain and differential time constant, • PID circuit with a gain, integrator and 1- and 2-power differentiators, • Skip module that provides a frequency gap between the two given levels. There are two graphic formats − .wmf (Windows metafile) and .bmp (raster format) suitable for saving a chart of the signals. IV. SIMULATION To execute simulation, the Result module is destined (Fig. 3). There are three modes of simulation − Dynamics, Statics, and Analysis. The Dynamics mode represents the speed transients of the mechanism and the torque (current) transients of the motor. The transient representation depends on the required Simulation result. When the Elastic transmission is simulated, the motor speed is plotted in addition to the load speed. The simulation time is ordered by a designer
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Fig. 3. Result window
Fig. 4. Database window
or it may be calculated automatically. Model discreteness is equal to 1 ms, and the permissible simulation time continues between 4 ms and 10 s. When there is neither the reference speed nor the converter selected, the model represents the rated speed of the motor. In cases the reference speed is not defined and the converter type is given, the model shows the motor rotor rotation with the speed that depends on the converter voltage and frequency. In the other cases, the motion of the system is simulated in accordance with the controller and converter gains. The Statics mode displays the speed-current or speed-torque relations in the open-ended system while electromagnetic phenomena are neglected. The Analysis mode produces • timing table of the torque, current, and speed instantaneous values in each simulation point; • summary of the maximum, minimum, and steady values of variables; • data calculated in the process of simulation; • summary of the service factors of the drive equipment calculated as the steady-to-rated (in the case of the step input signal) or rms-torated (in other cases) percentage ratio. The diagrams are scaled automatically along with simulation. To determine the scale of the time axes manually, a designer should specify the required simulation time. Zooming and Panoraming sub-modes help to find the best view of the results. To save and print the simulation results, the graphic format .wmf (Windows metafile) or .bmp (raster format) may be selected. To prepare the simulation report, the special Report generator is used. The report preview window Print Preview informs about • model name and report creation date, • dynamic and static diagrams of the corresponding tabs of the Result window, • model data from the Model window fields, • summary of the maximum, minimum, and steady values of variables, equipment service factors, and calculated data from the Analysis tab of the Result window. The content of the report may be controlled by a designer. The zooming procedure helps to rescale the report in the preview window and to move the pointer along the multi-page report. Four formats are accessible to save the report. The graphic format .qrp (QuickReport
file) supports the eDrive program that may be used to open and print the report. The .htm (HTML document) format is intended for the Internet publications. The .csv (Comma separated) text format is suitable to represent documents with delimiters, particularly for MS Excel. The .txt (Text file) plain text format may be used in such editors as Notebook and in email messages. V. DATABASE AND QUERIES A database is the source of information to develop and design an electric drive. Each eDrive release includes the protected MS Access database file eDrive.mdb. It consists of the motor, converter, and gear tables followed by the contents sheet (Fig. 4). Users may design their own MS Access databases and other database management systems, which should follow the relational database standards. The built-in text editor is a part of the Database management system. It may be used to write and edit different texts − the database memo fields, eDrive models (.edm files), queries (.sql files), etc. While the contents sheet is open, the editor displays the memo field of an active record where the company and the table descriptions are given. If any other sheet is open, the editor displays the description of the table fields. Besides the tables, a user may work with queries, which serve as other source of model information. A designer may produce queries in the SQL language having the Text mode. The Smart Query Builder helps to build combined multi-table queries to search the optimal composition of motors, converters and gears. To build the query, the types of converters, motors, and gears are selected and the load data are specified. Then, Builder generates a SQL statement. Following the query running, the resulting virtual dataset appears on the Sheet tab, which performs like a usual table. A user may save each new query in a separate text file. Alternately, he may open the earlier saved queries and repeat their implementation. Using the Export to Model mode, a designer sends a copy of an active record of a table or query to the model of the designed electric drive. When the Export to Model command is executed, the required tabs of the Model window are filled. In such a way, one may fill in the Motor, Supply and Load tabs separately using the necessary tables, or he fills them simultaneously using a multi-table query.
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VI. EDRIVE AGAINST COMPETITIVE TOOLBOXES Comparison of the simulated characteristics generated by different toolboxes is an important stage of eDrive analysis. To select the appropriate simulation software and the appropriate models, a designer requires a detailed understanding of the properties and limitations of the toolboxes and the sensitivity of the results to the model limitations. In order to obtain such an understanding, the numerous simulation tests were performed. We carefully scrutinized the results and compared them with measured data and results from other simulation packages.
eDrive was compared with Matlab (Simulink) [11], PSIM [12], and Multisim [13]. The comprehensive set of comparative data of the toolboxes is tabulated below. Here, the term “virtual” is used to designate the common-mode models the data of which are specified by the user. The “ready-to-service modules” are the virtual model blocks comprising the elementary electronic components the data of which are specified by the user. The “manufacturer’s databases” are the models of the ready-to-service products applied for simulation without their change by the user.
TABLE I. SIMULATION QUANTITIES OF TOOLBOXES PSIM Matlab ver. 6 ver. 7 Simulation of IGBT power switches Overall number of parameters of virtual IGBT 4 8 Number of manufacturer’s databases of IGBTs 0 0 Simulation of electronic components besides IGBTs Overall number of types of virtual component simulators 83 90 including the number of virtual transistor simulators 4 2 including the number of virtual diode simulators 3 1 including the number of virtual passive circuit simulators 7 28 including the number of virtual analogue and digital circuit 80 29 simulators including the number of virtual source simulators 33 7 Number of manufacturer’s databases of electronic components besides 0 0 IGBTs Simulation of the ready-to-service modules of power converters Overall number of types of virtual converter simulators 8 2 including the number of virtual ac/dc converter simulators 6 3 including the number of virtual dc/ac converter simulators 2 3 including the number of virtual ac/ac converter simulators 0 0 including the number of virtual dc/dc converter simulators 0 0 Number of manufacturer’s databases of the ready-to-service modules of 0 0 power converters Simulation of induction squirrel-cage motors Number of winding parameters 5 5 Number of other electrical parameters 3 3 Number of mechanical parameters 2 2 Number of manufacturer’s databases of induction squirrel-cage motors 0 0 Simulation of electric drives, besides induction squirrel-cage motors Overall number of types of virtual motor simulators 5 4 Number of manufacturer’s databases of motors besides induction 0 0 squirrel-cage motors Overall number of types of virtual gearbox simulators 1 8 Number of manufacturer’s databases of gearboxes 0 0 Overall number of types of virtual loop controllers 0 3 Overall number of types of virtual sensors 6 1 Overall number of types of virtual filters 4 24 Exploring and analyses Overall number of types of virtual measuring devices 12 12 Overall number of types of virtual signal generators 6 16 Steady-state analysis 0 1 Transient analysis 4 4 Frequency analysis 0 1 Spectral analysis 0 1 Quantity
As the table shows, the most suitable tools for the power converter development and study are Matlab and PSIM as the more specialized towards the power electronics and motor drives application area. To design the low-power electronic circuits, Multisim is one of the most widely used general-purpose simulation programs having the best set of simulation quantities whereas eDrive does not
Multisim ver. 9
eDrive ver. 12
0 1
0 0
>400 20 5 >70
0 0 0 0
>100
0
32
0
>100
0
5 1 0 1 3
3 1 1 1 0
0
17
6 0 0 0
5 4 5 5
5
3
0
10
0 0 0 >20 1
4 5 3 3 11
>30 >10 3 >5 1 1
6 9 2 3 0 0
suit this problem at all. On the other hand, eDrive proposes many possibilities to study electrical motors in different modes of driving operation and to design an electrical drive using the ready-to-service components from the industrial databases. Multisim (as well as SPICE) does not fit the requirements of studying the drive. Therefore, PSIM and Matlab serve as the main
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candidates to solve the building and exploring problems of the driving applications. To solve the exploring problems and to develop electric drives on the base of the real industrial components, eDrive may be recommended. To compare eDrive with other toolboxes, an experimental workplace was organized at the Department of Electrical Drives and Power Electronics of Tallinn University of Technology. It consists of two electric drives ACS800 series – the testing drive and the loading drive. To control electric drives, ABB DriveWindow software has been installed. Each drive has the same structure, consisting of an induction motor, power converter, remote console, as well as the cabinet, housing, measuring, and cabling equipment. The motor shafts of the drives have been mechanically coupled to provide their joint rotation. Both power converters are wall-mountable low-harmonic units supplying the motors. Each includes the line-side active rectifier and the motor-side inverter connected via the dc link. The tested motor M33AA 132S has the following characteristics: rated power 5,5 kW, voltage 400 V, current 11 A, speed 1460 r/min, torque 36 Nm, moment of inertia 0,038 kgm2. The loading motor M33AA 160L has the following characteristics: rated power 15 kW, voltage 400 V, current 29 A, speed 1460 r/min, torque 98 Nm, moment of inertia 0,102 kgm2. The power converters ACS800 enable two modes of operation: voltage/frequency control and direct torque control with direct and indirect measuring of the motor speed, torque, and current. Their technical data are as following: input voltage 400 V, output voltage from 0 to 415 V, output frequency from 8 to 300 Hz, output power 75 kW with the speed and torque scalar and vector control, flux and mechanical brake, acceleration and deceleration ramps. The aim of the verification stage of research was to study the differences of the transient and steady-state characteristics between the tested drive and the simulated ones. Two motor running modes were compared: direct start-up from the industrial mains and inverter-fed motor running. Both the idle running (5 Nm) and the nominal loading (36 Nm) operations were compared. The power converter model designed in PSIM environment was accomplished with the induction motor, loading device, and independent bridge-connected IGBT simulator. For clarity this circuit has been realized using only standard elements from the libraries of the evaluation versions. The basic principle of the operation of the gate drive circuit is the well-known carrier-based PWM scheme, where a control voltage is compared with a triangular carrier with fixed amplitude. In Matlab, the SimPower Systems library was used. To study the converter-fed drive, the virtual motor simulator with the Constant loading device was connected to the built-in inverter Universal Bridge supplied from the DC Voltage Source and controlled by the Discrete PWM Generator. The eDrive model was developed on the basis of the ready-to-service ABB motor and converter simulators. The results of simulations (Fig. 5, 6, 7, 8) qualitatively are in agreement with the experimental preconditions and suitable to evaluate the situation quantitatively. However, it is evidently that even the modern simulation programs cannot perfectly represent all parameters and aspects of real equipment. The accuracy of the simulation results depends on the accuracy of the component models and
the proper identification and inclusion of auxiliary circuit elements such as parasitic inductance, capacitance and mutual coupling. Accuracy of component models in this context shall not mean that the model is actually faulty but rather that the limitations of the model are exceeded. In particular, the precise prediction of voltage and current traces during the fast switching transitions in power electronics circuits has been proven to be difficult. In addition, numerical convergence is often a problem, if the gate driver signals, with rise and fall times as steep as in real circuits, are applied. Therefore, the exact prediction of waveforms during switching transitions was excluded from the discussions in this paper. Multisim is weak to simulate the mechanical loading modes of the drive performance. Alternately, eDrive is unsuitable for original electronic circuit design. Therefore, neither of them is recommended for the
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Fig. 5. Screen dumps of experimental start-up of the inverterfed loading drive: current trace obtained using oscilloscope TPS 2000 and speed trace from ABB DriveWindow.
Fig. 6. Screen dumps of the eDrive simulation of the inverterfed loading drive start-up: speed-current and the speed-torque traces.
VII. CONCLUSION Different design, research, and educational problems concerning the synthesis and study of complex electric drives may be effectively solved using the toolbox built as an object-oriented system proposed in the paper. Specific facilities of various engineering, technological and theoretical decisions integrated into the eDrive toolbox are offered. Equipment selection, simulation, and tuning methods have an effect both on the structure and the dynamic performance of the equipment developed. Benefits of the technology described have a significant impact on the project capacity and the total cost of a desired system. ACKNOWLEDGMENT This paper was supported by the projects DAR 8130 and ETF 8020. Fig. 7. Screen dumps of the PSIM simulation of the inverterfed loading drive start-up: current, speed and torque traces.
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[3] [4]
[5]
[6]
[7] Fig. 8. Screen dumps of the Matlab simulation of the inverter-fed loading drive start-up: current, speed and torque traces.
[8]
accurate exploring of the control principles of power converters operated under variable loads. In their turn, Matlab and PSIM yield similar results. However, their simulation processes are quite time-consuming: PSIM requires 12 s and Matlab 81 s to perform the simulation cycle, whereas eDrive takes only 4 s for the same operation. Both packages need in highly qualified specialists to build and tune the model as well as to perform simulation. Note that to use eDrive, it is sufficient to be a specialist in electrical drive only.
[9]
[10] [11] [12] [13] [14]
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V. Vodovozov, “The educational resources of mechatronics,” Mechatronics, v. 5(1), 1995, pp. 15-24. Drive engineering — Practical implementation. Volume 1. Drive Arrangements with SEW Geared Motors. Calculation Methods and Examples, SEW Eurodrive, 1998. Siemens Standard Drives. Application Handbook, Congleton, 1997. S. Cetinkunt, “Optimal design issues in high-speed highprecision motion servo systems,” Mechatronics, v. 1(2), 1991, pp. 187-201. F. Roos, H. Johansson, and J. Wikander, “Optimum selection of motor and gearhead in mechatronic applications,” Mechatronics, v. 16(1), 2006, pp. 16-24. V. Vodovozov and A. Loparev, “Simulation tools for design and testing of electric drives,” 11th International Power Electronics and Motion Control Conference (EPE-PEMC 2004), Riga, Latvia, 2004, paper DS 7.16. V. Vodovozov and Z. Raud, “Model-based learning in electric drive design,” The 2008 European Simulation and Modelling Conference (ESM 2008), Le Havre, France, 2008, pp. 355-359. J. M. Usher, “A tutorial and review of object-oriented design of manufacturing software systems,” Computers and Industrial Engineering, v. 30(4), 1996, pp. 781-798. V. Vodovozov and J. Laugis, “Object-oriented electric drive development technology,” IEEE International Electric Machines and Drives Conference (IEMDC 2007), Antalya, Turkey, 2007, paper AF000434. R. Krishman, Electric motor drives: Modeling, analysis, and control, Prentice Hall, 1996. Simulink - Simulation and model-based Design, Available at: http://www.mathworks.com/ products/simulink/ PSIM simulation software, Available at: http://www.psim-europe. com/ National Instruments Multisim, Available at: http://www.ni.com/ multisim/ eDrive - Toolbox to design electric drives, Available at: http://edrive.narod.ru
