Pwm Acoustic Noise Reduction For Permanent Magnet Synchronous Motors Based On Highly Coupled Dual-branch Topology

High frequency vibration and noise are caused by PWM harmonics in the motor phase current.At present,two aspects including hardware and control strategy are concentrated to suppress the PWM high frequency noise,such as the employment of wide bandgap semiconductors with higher switching frequencies.periodic or random carrier frequency modulation,parallel inverters with carrier phase shift technology.These measures have the problems of limited suppression effect and high cost.This paper proposes a highly-coupled dual-branch PMSM based on highly coupled dual-branch topology and its drive strategy.By changing the phase difference of the PWM harmonic currents in the two branches,the synthesized magnetomotive force harmonics are suppressed.Also,the motor model,drive topology and modulation algorithm have been comprehensively studied,which effectively suppresses the PWM high-frequency vibration and noise.For the highly coupled dual-branch PMSM,two coil placement methods are analyzed and impedance-balanced winding design methods are proposed,and the coupling coefficients of the motor windings of different topologies are analyzed.In the three-phase coordinate system and the rotating coordinate system,the state equation of the highly coupled dual-branch PMSM is established,and then the fundamental wave and harmonic equivalent circuit of the motor is obtained.Based on the equivalent circuit,the change rule of the motor current under the condition of different carrier phases of the winding is analyzed.An experimental platform for driving a strong-coupled dual-branch PMSM with parallel inverters is built,and the change law of PWM harmonics in the phase current and the synthesized phase current after the carrier phase shift is studied.Aiming at the highly coupled dual-branch PMSM drive system with the carrier in phase,the VEA-SVPWM（vector exchange asymmetrical SVPWM）algorithm based on triangular wave carrier asymmetric regular sampling is proposed.By exchanging the effective vector position of the second half cycle,the frequency of output PWM waveforms of phase voltage is doubled.The expression of output PWM voltage using VEA-SVPWM is derived with two-dimensional Fourier transform,which is theoretically proved that this method can significantly reduce the amplitude of sideband harmonics near odd multiples of carrier frequency.For the2^nd and 4^th low-frequency harmonics caused by VEA-SVPWM,an adaptive algorithm of injecting d-axis compensation voltage is proposed to realize the suppression of low-frequency current harmonics.Combining the characteristics of periodic carrier frequency modulation and VEA-SVPWM,the VEA-SVPWM carrier frequency is changed according to a periodic function,which not only greatly reduces the harmonic noise of the harmonics near the odd multiples of the carrier frequency,but also suppresses the PWM noise near the even multiples of the carrier frequency.Simulation and experiment verify the effectiveness of the proposed method.When applying the carrier phase shifting technology for highly coupled dual-branch PMSM,a highly coupled dual-branch PMSM isolated interleaved parallel driving strategy is proposed.The harmonic equivalent circuit model of the drive system is established,the influence of the harmonic components of the phase current summation with different carrier phase shift difference is analyzed,and the design criteria of the coupled inductor is clarified.Therefore,the phase difference control of the harmonic current is realized to make the harmonic magnetomotive force cancel each other out,thereby eliminating the PWM noise of specific frequency.Aiming at the problem that the asymmetry of the branch current caused by the current sampling error causes the coupling inductance to saturate and affect the harmonic suppression effect,an adaptive linear neuron algorithm based on the rotor position is proposed to extract the DC feedback signal,eliminate the disturbance signal,and make the three-phase current symmetric.The structure of the hybrid interleaved parallel topology is used for the highly coupled dual-branch PMSM,and the interleaved parallel connection of inverters is used to prevent the harmonics from passing through the windings and the canceling out characteristics of harmonic magnetomotive force generated by the two sets of windings of the dual-branch motor is employed.The phase difference control strategy realizes the elimination of sideband harmonics near 1-3 times the carrier frequency in the sum of currents.Based on the harmonic equivalent circuit,the elimination mechanism of the sideband harmonics near the carrier frequency of different multiples is revealed,and the simulation verifies the effectiveness of the method.Focusing the problem that a single method cannot suppress the high frequency PWM noise nearby multiple carrier frequency,a PWM noise multi-strategy combined suppression method is proposed on the basis of an isolated interleaved parallel topology driving a highly coupled dual-branch PMSM.Carrier phase shifting and periodic frequency modulation are combined to achieve effective suppression of PWM noise near odd carrier frequencies,and at the same time reduce noise near even carrier frequencies.Theoretical analysis and experiments show the effectiveness of the modified combination strategy and the frequency band distribution characteristics.For the remaining harmonic noise of even carrier frequency,a control strategy combining VEA-SVPWM and carrier phase shift is proposed,which effectively suppresses the PWM noise near 2 times the carrier frequency.In order to suppress the remaining harmonic noise near 4 times the carrier frequency,on the basis of the above method,the carrier frequency is periodically changed to realize the suppression of PWM noise near 4 times the carrier frequency.The experiment verifies the effectiveness of the multi-strategy combined technology in comprehensively suppressing PWM noise.