Title in Conference Program: Improvement of electromagnetic compatibility of motor drives using hybrid chaotic PWMSession FZ: Magnetoimpedance, High Frequency Materials and Electromagnetic Compatibility: FZ-09This paper proposes and implements a new hybrid chaotic (HC) pulse width modulation (PWM) scheme for the reduction of electromagnetic interference (EMI) in alternating current (AC) motor drives. This scheme utilizes logistic mapping to simultaneously chaoize both the carrier frequency and the pulse position. Compared with available chaotic PWM schemes such as the chaotic-pulse-position- modulated (CPPM) PWM and the chaotic-amplitude-frequency-modulated (CAFM) PWM, the proposed scheme is a synergy of CPPM-PWM and CAFM-PWM. Thus, it possesses a hybrid characteristic, namely the peaky EMI is suppressed while the occurrence of low-order noises is reduced. Both simulation and experimental results are provided to support the validity. © 2011 IEEE.published_or_final_versionThe IEEE International Magnetic Conference (INTERMAG2011), Taipei, Taiwan, 25-29 April 2011. In IEEE Transactions on Magnetics, 2011, v. 47 n. 10, p. 4018-402

Chau, KT

Li, W

Wang, Z

Zhang, Z

IEEE Transactions on Magnetics

This paper proposes and implements a new hybrid chaotic (HC) pulse width modulation (PWM) scheme for the reduction of electromagnetic interference (EMI) in alternating current (AC) motor drives. This scheme utilizes logistic mapping to simultaneously chaoize both the carrier frequency and the pulse position. Compared with available chaotic PWM schemes such as the chaotic-pulse-position- modulated (CPPM) PWM and the chaotic-amplitude-frequency-modulated (CAFM) PWM, the proposed scheme is a synergy of CPPM-PWM and CAFM-PWM. Thus, it possesses a hybrid characteristic, namely the peaky EMI is suppressed while the occurrence of low-order noises is reduced. Both simulation and experimental results are provided to support the validity. © 2011 IEEE.link_to_subscribed_fulltextThe IEEE International Magnetic Conference (INTERMAG2011), Taipei, Taiwan, 25-29 April 2011. In IEEE Transactions on Magnetics, 2011, v. 47 n. 10, p. 4018-402

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Title Improvement of electromagnetic compatibility of motor drivesusing hybrid chaotic pulse width modulationAuthor(s) Zhang, Z; Chau, KT; Wang, Z; Li, WCitationThe IEEE International Magnetic Conference (INTERMAG2011),Taipei, Taiwan, 25-29 April 2011. In IEEE Transactions onMagnetics, 2011, v. 47 n. 10, p. 4018-4021Issued Date 2011URL http://hdl.handle.net/10722/140222Rights Creative Commons: Attribution 3.0 Hong Kong License4018 IEEE TRANSACTIONS ON MAGNETICS, VOL. 47, NO. 10, OCTOBER 2011Improvement of Electromagnetic Compatibility of Motor Drives UsingHybrid Chaotic Pulse Width ModulationZhen Zhang , K. T. Chau , Zheng Wang, and Wenlong Li Department of Electrical and Electronic Engineering, The University of Hong Kong, Hong Kong, ChinaSchool of Electrical Engineering, Southeast University, Nanjing, Jiangsu 210096, ChinaThis paper proposes and implements a new hybrid chaotic (HC) pulse width modulation (PWM) scheme for the reduction ofelectromagnetic interference (EMI) in alternating current (AC) motor drives. This scheme utilizes logistic mapping to simultaneouslychaoize both the carrier frequency and the pulse position. Compared with available chaotic PWM schemes such as the chaotic-pulse-po-sition-modulated (CPPM) PWM and the chaotic-amplitude-frequency-modulated (CAFM) PWM, the proposed scheme is a synergy ofCPPM-PWM and CAFM-PWM. Thus, it possesses a hybrid characteristic, namely the peaky EMI is suppressed while the occurrenceof low-order noises is reduced. Both simulation and experimental results are provided to support the validity.Index Terms—Chaos, electromagnetic compatibility, electromagnetic interference, motor drives, pulse width modulation.I. INTRODUCTIONS INCE the switching frequency of pulse width modulation(PWM) schemes for alternating current (AC) motor drivesis significantly raised for the reduction of their size and weight,the electromagnetic interference (EMI) is increased inevitably,which results in the degradation of electromagnetic compati-bility (EMC) for electronic devices [1], [2]. In order to reducethe peaky EMI which usually occurs when using the fixed-fre-quency (FF) PWM [3], [4], various chaotic PWM schemes suchas the chaotic-pulse-position-modulated (CPPM) PWM and thechaotic-amplitude-frequency-modulated (CAFM) PWM havebeen proposed [5], [6]. For the CPPM-PWM scheme, the pulseposition is varied chaotically in every switching cycle. It canspread the discrete spectral power over a continuous spectrumso that the peaky EMI is significantly reduced. Nevertheless,some peaky EMI still exist at certain frequencies. For theCAFM-PWM scheme, the Logistic map is employed to chaoizea frequency-modulated signal which in turn modulates theslope of the triangular carrier. It can effectively suppress allpeaky EMI over the whole power spectrum. However, there arenoticeable low-order harmonics.In this paper, a new hybrid chaotic (HC) PWM scheme isproposed and implemented for AC motor drives, which cansuppress the peaky EMI and reduce the occurrence of low-ordernoises. The key is to simultaneously chaoize both the pulseposition and the carrier frequency for the generation of PWMpulses. In order to illustrate the validity and merits of theproposed HC-PWM, both computer simulation and experi-mental verification will be given to compare the power spectraresulted from the FF-PWM, CPPM-PWM, CAFM-PWM andHC-PWM schemes. Finally, the proposed HC-PWM will befurther compared with the well-known random-frequency (RF)PWM scheme [7], [8].Manuscript received February 20, 2011; revised April 29, 2011; acceptedApril 29, 2011. Date of current version September 23, 2011. Correspondingauthor: Z. Zhang (e-mail: zhzhang@eee.hku.hk).Digital Object Identifier 10.1109/TMAG.2011.2152371Fig. 1. HC-PWM inverter-fed AC motor drive.II. HYBRID CHAOTIC PWMFor a typical inverter-fed AC motor drive as shown in Fig. 1,the common-mode (CM) currents are between the phases andthe system ground, whereas the differential-mode (DM) cur-rents are between different phases of the PWM inverter [9], [10].Both the CM and DM currents are the main sources of EMI. Inorder to reduce or even suppress the EMI, it is imperative to im-prove the spectrum of inverter output voltages.As shown in Fig. 2, the proposed HC-PWM scheme is a com-bination of the modulation of the carrier frequency by a chaoticsequence and the variation of pulse positions by chaotic bits ineach switching cycle. This scheme is different from the avail-able chaotic PWM schemes, such as the CPPM-PWM which isbased on chaotic pulse positions under a fixed carrier frequencyor the CAFM-PWM which is based on a chaotic carrier fre-quency under fixed pulse positions.The proposed HC-PWM adopts the same chaotic sequenceto chaoize both the carrier frequency and the pulse position.This chaotic sequence is generated by the Logisticmap which can be expressed as where. The Logistic map is a one-dimensional dis-crete-time nonlinear system, which can exhibit plenty of dy-namical behavior, including chaos. The corresponding bifurca-tion diagram is generated by plotting the extreme points ofnearby the stable or unstable solutions with respect to differentvalues of as shown in Fig. 3(a), which illustrates that can beused to tune the spectral power distribution from no frequency0018-9464/$26.00 © 2011 IEEEZHANG et al.: IMPROVEMENT OF ELECTROMAGNETIC COMPATIBILITY OF MOTOR DRIVES USING HYBRID CHAOTIC PULSE WIDTH MODULATION 4019Fig. 2. Logic circuitry for HC-PWM generation.Fig. 3. Logistic map. (a) Bifurcation diagram. (b) Lyapunov exponent.modulation (FM), to periodic FM, to multi-periodic FM and fi-nally to chaotic FM. As shown in Fig. 3(b), the maximum Lya-punov exponent, which denotes the rate of the attractor growthin the state space by the direction of maximum growth, is plottedwith respect to different values of . It indicates that chaoticbehavior occurs for , so is selected forchaoization.Firstly, the chaoization of the carrier frequency is carried outby adding a multiplication factor, namely the generated by theLogistic map, to the conventional FF-PWM. Thus, the switchingfrequency can be expressed as:(1)where is the real switching frequency, is the fixedswitching frequency, is the deviation frequency and isthe modulation frequency. Secondly, the chaoization of pulsepositions is carried out by a train of chaotic bits whichis also generated by the Logistic map. This chaotic bit trainfunctions to modulate the pulse position signal which isresulted from a comparison between the carrier signal andthe reference signal as given by:(2)Consequently, the desired HC-PWM signal is generated by ap-plying the AND operator to and as depicted in Fig. 4.III. SIMULATION RESULTSComputational simulation of those aforementioned PWMschemes is carried out by Matlab Simulink. The AC motorparameters are based on a practical induction motor as listed inTable I. By using the periodogram method, all power spectraof and based on using the FF-PWM, CPPM-PWM,Fig. 4. Waveforms of HC-PWM generation.TABLE IPARAMETERS OF INDUCTION MOTORFig. 5. Simulated power spectra of FF-PWM. (a)   . (b)   .CAFM-PWM and HC-PWM are computed from zero to 150kHz under the same and . The corresponding powerspectra from zero to 20 kHz are shown in Figs. 5–8. It can beobserved that the FF-PWM spectra are crowded with peakyEMI while the CPPM-PWM spectra are imposed with occa-sional peaky EMI, whereas both the CAFM-PWM and theHC-PWM can suppress all peaky EMI.Two performance indicators are employed for the assessmentof the EMC of this motor drive. Since the conducted EMI with afrequency exceeding 9 kHz is stringently limited by many coun-tries, the maximum power spectral density (PSD) in 9–150 kHzis used as the first performance indicator. In order to evaluate thecontent of low-order noises while the power spectrum is mainlyfrom to , the spectral power in 2.99–3.01kHz is used as another performance indicator.Firstly, by comparing the maximum PSD of theirspectra in 9–150 kHz, namely 10.03 dBm/Hz for the FF-PWM,6.04 dBm/Hz for the CPPM-PWM, 2.22 dBm/Hz for the4020 IEEE TRANSACTIONS ON MAGNETICS, VOL. 47, NO. 10, OCTOBER 2011Fig. 6. Simulated power spectra of CPPM-PWM. (a)   . (b)   .Fig. 7. Simulated power spectra of CAFM-PWM. (a)   . (b)   .Fig. 8. Simulated power spectra of HC-PWM. (a)   . (b)   .CAFM-PWM and 11.88 dBm/Hz for the HC-PWM, it il-lustrates that the HC-PWM has a remarkable improvementover other PWM schemes. Similarly, from their spectra,namely 14.78 dBm/Hz for the FF-PWM, 11.58 dBm/Hz forthe CPPM-PWM, 0.61 dBm/Hz for the CAFM-PWM and1.78 dBm/Hz for the HC-PWM, it indicates that both theCAFM-PWM and HC-PWM have significant improvementover the others while the HC-PWM is the better than theCAFM-PWM.Secondly, by comparing the spectral power of theirspectra in 2.99–3.01 kHz, namely 10.03 dBm for theFF-PWM, 17.14 dBm for the CPPM-PWM, 2.22 dBm for theCAFM-PWM and 19.55 dBm for the HC-PWM, it illustratesthat both the CPPM-PWM and the HC-PWM have a remark-able improvement over other PWM schemes. Then, from theirspectra, namely 14.78 dBm for the FF-PWM, 11.72dBm for the CPPM-PWM, 1.42 dBm for the CAFM-PWMand 17.57 dBm for the HC-PWM, it confirms that both theCPPM-PWM and HC-PWM have significant improvement overthe others while the HC-PWM is better than the CPPM-PWM.Fig. 9. Measured power spectra of FF-PWM. (a)   . (b)   .Fig. 10. Measured power spectra of CPPM-PWM. (a)   . (b)   .On the basis of the two performance indicators, the proposedHC-PWM scheme exhibits a hybrid characteristic, possessingnot only an exceptional improvement on the suppression ofpeaky EMI and maximum PSD in 9–150 kHz (the merit of theCAFM-PWM), but also a remarkable performance in 2.99–3.01kHz (the merit of the CPPM-PWM). Therefore, the HC-PWMcan offer better performance than other chaotic PWM schemes.IV. EXPERIMENTAL RESULTSFor experimentation, a practical 3-phase 4-pole 1.5-kW220-V induction motor is adopted. The parameters of thisinduction motor for experimental tests are the same as that forcomputational simulations listed in Table I. All the aforemen-tioned PWM schemes are implemented by a single-chip dig-ital-signal-processing microcontroller (Texas TMS320F2812),including the chaoization of both pulse positions and carrierfrequencies, the comparing and generating logics, and theerror handling process. The output of this microcontroller isthe chaoized PWM signals which are used to fed into a driverboard. This driver board is designed to convert directly thecontrol signal 0 3.3 V to the gate driving signal 0 15 V. Thepower stage is based on a six-in-one integrated power module(Mitsubishi PM75RLA120) which serves as the PWM inverterfor the induction motor.All power spectra of the FF-PWM, CPPM-PWM,CAFM-PWM and HC-PWM are directly measured by thepower spectrum analyzer (LeCroy WR6100A). By comparingFig. 9, Fig. 10, Fig. 11 and Fig. 12, it can be seen that the peakyEMI can be effectively suppressed by using the CAFM-PWMZHANG et al.: IMPROVEMENT OF ELECTROMAGNETIC COMPATIBILITY OF MOTOR DRIVES USING HYBRID CHAOTIC PULSE WIDTH MODULATION 4021Fig. 11. Measured power spectra of CAFM-PWM. (a)   . (b)   .Fig. 12. Measured power spectra of HC-PWM. (a)   . (b)   .TABLE IICOMPARISON OF EXPERIMENTAL RESULTSand HC-PWM schemes. Also, the maximum PSD measuredin 9–150 kHz and the power spectra measured in 2.9–3.1 kHzare quantitatively compared in Table II which indicates thatthe HC-PWM can offer lower EMI than the CAFM-PWM interms of the low-order noises around 3 kHz. Therefore, it isexperimentally verified that the proposed HC-PWM can offerbetter performance than other chaotic PWM schemes.V. FURTHER COMPARISONIn order to further identify the merit of the proposedHC-PWM, it is compared with the RF-PWM scheme whichis well known in suppressing peaky EMI. Since both of themcan suppress the peaky EMI, the comparison is based on theirlow-order noises in 2.99–3.01 kHz and the immunity of me-chanical resonance which is calculated as 10.19–10.21 kHz byusing the Holzer method. From their spectra in 2.99–3.01kHz, namely 11.88 dBm for the HC-PWM and 2.84 dBmfor the RF-PWM, the HC-PWM shows a better performance.Also, from their spectra, namely 1.78 dBm for theHC-PWM and 0.14 dBm for the RF-PWM, it confirms that theHC-PWM possesses a better performance on the suppressionof low-order noises than the RF-PWM. Then, by comparingtheir spectra in 10.19–10.21 kHz, namely 21.59 dBmfor the HC-PWM and 16.93 dBm for the RF-PWM, andtheir spectra, namely 12.62 dBm for the HC-PWM and9.42 dBm for the RF-PWM, it shows that the HC-PWM ismore immune from mechanical resonance than the RF-PWM.VI. CONCLUSIONIn this paper, a new hybrid chaotic PWM scheme has beenproposed and implemented for AC motor drives, which caneffectively suppress the peaky EMI and low-order noises. Thekey of the proposed scheme is to simultaneously chaoize boththe carrier frequency and the pulse position. It shows betterperformance than the available chaotic PWM schemes in-cluding the CPPM-PWM and the CAFM-PWM. Additionally,it is better than the RF-PWM in terms of the immunity ofmechanical resonance.ACKNOWLEDGMENTThis work was supported in part by a grant (Project No.HKU710710E) from the Hong Kong Research Grants Council,Hong Kong Special Administrative Region, China.REFERENCES[1] A. M. Sitzia, A. E. Baker, T. W. Preston, A. Puzo, and A. Pons, “Finiteelement analysis for power electronics EMC applications,” IEEE Trans.Magn., vol. 32, pp. 1517–1520, 1996.[2] S. Wang and F. C. Lee, “Analysis and applications of parasitic capaci-tance cancellation techniques for EMI suppression,” IEEE Trans. Ind.Electron., vol. 57, pp. 3109–3117, 2010.[3] W. C. Lo, C. C. Chan, Z. Q. Zhu, L. Xu, D. Howe, and K. T. Chau,“Acoustic noise radiated by PWM-controlled induction machinedrives,” IEEE Trans. Ind. Electron., vol. 47, pp. 880–889, 2000.[4] S. Z. Jiang, K. T. Chau, and C. C. Chan, “Spectral analysis of a newsix-phase pole-changing induction motor drive for electric vehicles,”IEEE Trans. Ind. Electron., vol. 50, pp. 123–131, 2003.[5] Z. Wang, K. T. Chau, and C. H. Liu, “Improvement of electromag-netic compatibility of motor drives using chaotic PWM,” IEEE Trans.Magn., vol. 43, pp. 2612–2614, 2007.[6] Z. Wang and K. T. Chau, “Design and analysis of a chaotic PWM in-verter for electric vehicles,” in Proc. IEEE IAS Annual Meeting, 2007,pp. 1954–1961.[7] A. Carlosena, W. Chu, B. Bakkaloglu, and S. Kiaei, “Randomized car-rier PWM with exponential frequency mapping,” IEEE Trans. PowerElectron., vol. 22, pp. 960–966, 2007.[8] Y. Shrivastava, S. Sathiakumar, and V. G. Agelidis, “Analysis and veri-fication of two-level random aperiodic PWM schemes for DC-DC con-verters,” IEEE Trans. Power Electron., vol. 24, pp. 2138–2147, 2009.[9] L. Ran, S. Gokani, J. Clare, K. J. Bradley, and C. Christopoulos, “Con-ducted electromagnetic emissions in induction motor drive system partII: Frequency domain analysis and identification of dominant modes,”IEEE Trans. Power Electron., vol. 13, pp. 757–767, 1998.[10] K. T. Chau and Z. Wang, Chaos in Electric Drive Systems—Analysis,Control and Application. Singapore: Wiley, 2011.

Improvement of electromagnetic compatibility of motor drives using hybrid chaotic PWM

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Improvement of electromagnetic compatibility of motor drives using hybrid chaotic PWM

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