矢量控制永磁同步电动机低速轻载运行的研究

提出了削弱电压源型空间矢量脉宽调制逆变器死区效应的方法.给出因死区时间和开关器件开通、关断时间引起的误差电压矢量,依据误差电压矢量的表达式,采用降低载波频率和减小直流母线电压的方法削弱死区效应.分析了降低载波频率对磁链轨迹畸变和转矩脉动的影响,在低速空载情况下通过增大电机定子励磁电流分量获得连续电流波形,通过检测电流矢量角判断电流极性,对死区进行补偿.仿真并对比了不同载波频率下的转矩脉动,实验结果证明了所提出的方法能有效地降低电机转速,改善电流波形.

Study of Vector-Controlled Permanent Magnet Synchronous Motor at Low Speed and Light Load

Novel dead-time effect weakening methods for a voltage-fed space vector pulse width modulation(SVPWM)inverter are presented. Error voltage vector generated by dead-time,switching devices turn-on and turn-off time are introduced. Weakening methods that consist of decreasing carrier frequency and decreasing direct current bus voltage are educed.The flux linkage distortion and torque ripples caused by decreasing carrier frequency are analyzed.In order to make current waveform continue so that detect 3-phase current polarities,the stator field current component is increased when the motor operated at no load;By using the current vector angle,dead-time compensation is performed. Simulation results show that torque ripples are enlarged at lower carrier frequency. Experimental results verify that the proposed weakening methods can decrease effectively motor speed,and the compensation approach can improve effectively current waveform.