IEEE TRANSACTIONS ON MAGNETICS, VOL. 51, NO. 11, NOVEMBER 2015
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Periodic Carrier Frequency Modulation in Reducing Low-Frequency Electromagnetic Interference of Permanent Magnet Synchronous Motor Drive System Xu Yongxiang, Yuan Qingbing, Zou Jibin, Wang Baochao, and Li Junlong Harbin Institute of Technology, Harbin 150001, China This paper introduces the periodic carrier frequency modulation (PCFM) for permanent magnet synchronous motor (PMSM) drive systems so as to reduce the low-frequency electromagnetic interference (EMI). PMSMs are widely used in many applications and they are usually fed by pulsewidth modulation (PWM) inverters. The EMI of PMSM, which results from the switch of power device, generates undesirable effects on the control system. Therefore, it is of importance to reduce the EMI of PMSM. The common mode (CM) conducted EMI model of the PMSM drive system is constructed to investigate the CM voltage. The simulations and experiments of PMSM fed by the fixed frequency PWM (FFPWM) and PCFM are implemented to analyze the CM conducted EMI. The CM EMI spectra of PMSM fed by the FFPWM and PCFM with different spreading frequency widths are compared to explore the influence of PCFM on the CM conducted EMI. The regular patterns on PCFM in reducing the CM conducted EMI of PMSM drive systems are revealed. Index Terms— Electromagnetic interference (EMI), periodic carrier frequency modulation (PCFM), permanent magnet synchronous motor (PMSM).
I. I NTRODUCTION
P
ERMANENT magnet synchronous motors (PMSMs) have been widely employed in home appliances, medical instruments, and vehicles because of their various advantages such as the high power density, high efficiency, small size, and simple structure [1]–[4]. In addition, PMSMs are usually fed by pulsewidth modulation (PWM) inverters, whose power devices operate in switch states. The switch of power devices results in the electromagnetic interference (EMI) [5]. The EMI is a challenging problem for the motor drive system fed by PWM inverter due to the fact that the EMI noise generates undesirable effects on the control system such as the communication errors, degraded equipment performance, and malfunction [6], [7]. Therefore, it is of importance to improve the electromagnetic compatibility of PMSM drive systems employing proper strategy. In the literature, a set of methods have been used to reduce the EMI of power converters, such as filtering, shielding, grounding, isolation, separation, and the orientation. However, the passive filters and shielding may increase the significant cost and weight to power electronics systems. Spread spectrum clock generation (SSCG) can suppress the EMI of power converters without increasing the cost and weight. As a kind of SSCG, the periodic carrier frequency modulation (PCFM) was used to diminish the EMI of dc/dc power converters [8]. Furthermore, triangular PCFM was analyzed in reducing the acoustic noise of PMSM [9]. However, less attention has been paid to PCFM in reducing the EMI of PMSM drive systems. Therefore, this paper introduces PCFM for PMSM drive systems so as to improve the electromagnetic compatibility.
Manuscript received March 19, 2015; revised May 12, 2015 and May 19, 2015; accepted May 26, 2015. Date of publication June 2, 2015; date of current version October 22, 2015. Corresponding author: Zou Jibin (e-mail:
[email protected]). Color versions of one or more of the figures in this paper are available online at http://ieeexplore.ieee.org. Digital Object Identifier 10.1109/TMAG.2015.2440293
Fig. 1.
CM conducted EMI model of PMSM drive system.
II. C OMMON M ODE C ONDUCTED EMI M ODEL The common mode (CM) conducted EMI model of PMSM drive systems, as shown in Fig. 1, is constructed to analyze the CM EMI. The parameters in Fig. 1 are designated as follows: RCM = 1/(3R S ) L CM = 1/6(L sd + L sq )
(1) (2)
where R S is the phase resistance of the motor, L sd and L sq are the direct axis and quadrature axis inductances, respectively. CCM is the CM stray capacitor between motor windings and motor frame. C S is the stray capacitor across phase windings. C is the filter capacitor of rectifier bridge. L C and RC are the parasitic inductance and parasitic resistance of rectifier bridge filter capacitor, respectively. C p1 is the parasitic capacitor between inverter collector of the upper bridge and ground. C p2 is the parasitic capacitor between inverter emitter of the lower bridge and ground. C p is the parasitic capacitor between inverter midpoint of the bridge arm and ground. According to the impedance tests of PMSM, inverter and the parameters of PMSM, as shown in Table I, the characteristics in Fig. 1 are verified and thereafter shown in Table II.
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IEEE TRANSACTIONS ON MAGNETICS, VOL. 51, NO. 11, NOVEMBER 2015
TABLE I PMSM PARAMETERS
TABLE II EMI M ODEL PARAMETERS
Fig. 3. CM voltage spectrums of PMSM driven by sinusoidal PCFM with different spreading frequency widths. (a) 400 Hz. (b) 4000 Hz. (c) 8000 Hz.
Fig. 4. CM voltage spectrums of PMSM driven by sawtooth PCFM with different spreading frequency widths. (a) 400 Hz. (b) 4000 Hz. (c) 8000 Hz.
III. S IMULATIONS Fig. 2. CM voltage spectrums of PMSM drive system with FFPWM and PCFM. (a) FFPWM. (b) Sinusoidal PCFM. (c) Sawtooth PCFM.
The CM voltage in Fig. 1 can be expressed as follows: VCM = (V1 + V2 )/2
(3)
where V1 and V2 are the voltages across the two resistances of line impedance stabilization network, respectively.
Simulations of PMSM fed by the fixed frequency PWM (FFPWM) and PCFM are implemented to investigate the effect of PCFM on the CM conducted EMI. The power supply is 220 V/50 Hz ac voltage in the simulations. In addition, the switching frequency of the FFPWM and the center frequency of the PCFM are both 16 kHz. The CM voltage spectra of PMSM drive system with the FFPWM and PCFM are shown in Fig. 2. The low-frequency
YONGXIANG et al.: PCFM IN REDUCING LOW-FREQUENCY EMI OF PMSM DRIVE SYSTEM
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Fig. 5. Peak amplitudes about CM voltage spectrum of PCFM with different spreading frequency widths.
Fig. 7. CM conducted EMI spectrums of PMSM driven by sinusoidal PCFM with different spreading frequency widths. (a) 400 Hz. (b) 4000 Hz. (c) 8000 Hz.
Fig. 6. CM conducted EMI spectrums of PMSM driven by FFPWM and PCFM. (a) FFPWM. (b) Sinusoidal PCFM. (c) Sawtooth PCFM.
CM conducted EMI is the research focus in this paper. The frequency range of the CM voltage spectra in the simulations is set as 0–100 kHz. The CM voltage spectra of PMSM fed by the FFPWM concentrate at multiples of the switching frequency, as shown in Fig. 2(a). The concentration of the EMI coincides with the analysis in [10]. The peak amplitudes in the CM voltage spectra of PMSM with the sinusoidal and sawtooth PCFM are smaller than that with the FFPWM, as demonstrated in Fig. 2. It is obvious that the sinusoidal and sawtooth PCFM can effectively reduce the CM voltage of the PMSM drive system. The CM voltage spectra of PMSM driven by the sinusoidal and sawtooth PCFM with different spreading frequency widths are manifested in Figs. 3 and 4, respectively. The peak amplitudes in the CM voltage spectra of PMSM drive system
employing the sinusoidal and sawtooth PCFM with different spreading frequency widths are shown in Fig. 5. The peak amplitudes in the CM voltage spectra of PMSM with the sawtooth PCFM are smaller than that with the sinusoidal PCFM, as demonstrated in Fig. 5. Furthermore, the peak amplitudes in the CM voltage spectra of PMSM with the sinusoidal and sawtooth PCFM decrease as the spreading frequency widths increase. Simulation results indicate that the CM voltage of the PMSM drive system can be alleviated by the sinusoidal and sawtooth PCFM. In addition, the suppression of CM voltage of the PMSM drive system by the sinusoidal and sawtooth PCFM ameliorates with the increase in spreading frequency breadths. Moreover, the reduction on CM voltage of the PMSM drive system by the sawtooth PCFM is larger than that by the sinusoidal PCFM. IV. E XPERIMENTS Experimental tests of a PMSM prototype driven by the FFPWM and PCFM are performed to validate the foregoing simulations. The power supply is 220 V/50 Hz ac voltage in the experiments. In addition, the switching frequency of the FFPWM and the center frequency of the PCFM are both 16 kHz. Moreover, the PMSM prototype operates with 2000 r/min and 0.05 N·m load. The CM conducted EMI spectra of PMSM driven by the FFPWM and PCFM are shown in Fig. 6. The top line in Fig. 6, as defined by the 15-QP-cond, is the EN55015 quasi-peak value standard. The CM conducted EMI spectra of PMSM driven by the FFPWM concentrate at multiples
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IEEE TRANSACTIONS ON MAGNETICS, VOL. 51, NO. 11, NOVEMBER 2015
The peak amplitudes on the CM conducted EMI of PMSM driven by the sinusoidal and sawtooth PCFM with different spreading frequency widths are shown in Table III. Experimental results in Table III validate that the peak amplitudes on the CM conducted EMI spectra of PMSM driven by the sinusoidal and sawtooth PCFM decrease as the spreading frequency width increase. In addition, the peak amplitudes on the CM conducted EMI of PMSM driven by the sawtooth PCFM are smaller than that by the sinusoidal PCFM. V. C ONCLUSION The sinusoidal and sawtooth PCFM are introduced to reduce the low-frequency CM conducted EMI of PMSM drive systems in this paper. Simulation and experimental results validate that the sinusoidal and sawtooth PCFM can effectively reduce the CM conducted EMI. In addition, the sawtooth PCFM is more effective than the sinusoidal PCFM in suppressing the CM conducted EMI. Moreover, the reduction of the CM conducted EMI by the sinusoidal and sawtooth PCFM improves with the increase in spreading frequency widths.
Fig. 8. CM conducted EMI spectrums of PMSM driven by sawtooth PCFM with different spreading frequency widths. (a) 400 Hz. (b) 4000 Hz. (c) 8000 Hz. TABLE III P EAK A MPLITUDES ON THE CM C ONDUCTED EMI OF PMSM D RIVE S YSTEM W ITH S INUSOIDAL PCFM AND S AWTOOTH PCFM
of the switching frequency, as shown in Fig. 6(a). The peak amplitude of the CM conducted EMI spectra, which emerges near 48 kHz, is 90 dBµV. The concentration of the CM conducted EMI spectra are spread to the harmonic sidebands by the sinusoidal and sawtooth PCFM, as demonstrated in Fig. 6. The peak amplitudes of the CM conducted EMI spectra in Fig. 6(b) and (c), which emerge near 80 kHz, are 81 and 79 dBµV, respectively. The peak amplitudes in the CM conducted EMI spectra of PMSM driven by the sinusoidal and sawtooth PCFM are smaller than that by the FFPWM. Experimental results validate that the sinusoidal and sawtooth PCFM can effectively reduce the CM conducted EMI of PMSM drive systems. The CM conducted EMI spectra of PMSM driven by the sinusoidal and sawtooth PCFM with different spreading frequency widths are shown in Figs. 7 and 8, respectively.
ACKNOWLEDGMENT This work was supported in part by the National Natural Science Foundation of China projects under Grant 51437004 and in part by the National Key Basic Research Program of China under Grant 2013CB035605. R EFERENCES [1] K.-C. Kim, “A novel calculation method on the current information of vector inverter for interior permanent magnet synchronous motor for electric vehicle,” IEEE Trans. Magn., vol. 50, no. 2, Feb. 2014, Art. ID 7020504. [2] Y.-S. Park, M.-M. Koo, S.-M. Jang, J.-Y. Choi, and D.-J. You, “Dynamic characteristic analysis of interior permanent magnet synchronous motor considering varied parameters by outer disturbance based on electromagnetic field analysis,” IEEE Trans. Magn., vol. 50, no. 11, Nov. 2014, Art. ID 8202304. [3] G. Verez, G. Barakat, Y. Amara, and G. Hoblos, “Impact of pole and slot combination on vibrations and noise of electromagnetic origins in permanent magnet synchronous motors,” IEEE Trans. Magn., vol. 51, no. 3, Mar. 2015, Art. ID 8101104. [4] A. Kalimov and S. Shimansky, “Optimal design of the synchronous motor with the permanent magnets on the rotor surface,” IEEE Trans. Magn., vol. 51, no. 3, Mar. 2015, Art. ID 8101704. [5] Q. Huang, X. Wang, W. Zhen, and P. W. T. Pong, “Broadband point measurement of transient magnetic interference in substations with magnetoresistive sensors,” IEEE Trans. Magn., vol. 50, no. 7, Jul. 2014, Art. ID 6200505. [6] A. Nejadpak and O. A. Mohammed, “Physics-based modeling of power converters from finite element electromagnetic field computations,” IEEE Trans. Magn., vol. 49, no. 1, pp. 567–576, Jan. 2013. [7] M. Barzegaran, A. Mohamed, T. Youssef, and O. A. Mohammed, “Electromagnetic signature study of a power converter connected to an electric motor drive,” IEEE Trans. Magn., vol. 50, no. 2, Feb. 2014, Art. ID 7004804. [8] F. Pareschi, G. Setti, R. Rovatti, and G. Frattini, “Practical optimization of EMI reduction in spread spectrum clock generators with application to switching DC/DC converters,” IEEE Trans. Power Electron., vol. 29, no. 9, pp. 4646–4657, Sep. 2014. [9] Y. Xu, Q. Yuan, J. Zou, and Y. Li, “Analysis of triangular periodic carrier frequency modulation on reducing electromagnetic noise of permanent magnet synchronous motor,” IEEE Trans. Magn., vol. 48, no. 11, pp. 4424–4427, Nov. 2012. [10] A. Nejadpak, A. Sarikhani, and O. A. Mohammed, “Analysis of radiated EMI and noise propagation in three-phase inverter system operating under different switching patterns,” IEEE Trans. Magn., vol. 49, no. 5, pp. 2213–2216, May 2013.
