T型逆变器的共模干扰与共模电压抑制算法

摘要

在车辆电传动等大功率、高密度的交流调速场合,采用PWM控制时逆变器的共模干扰问题对电机和调速系统的影响和危害尤为突出.通过对T型逆变器电路拓扑和工作模态的研究,说明了逆变器共模电压的生成原因,得出了逆变器共模电压的傅里叶表达式,并分析了其谐波构成.其次,提出了T型逆变器的共模干扰等效模型,实验表明共模电压频谱的仿真与实验结果吻合,验证了高频模型的有效性.最后,提出了一种可以在理论上消除共模电压的调制波移相PWM算法,通过与传统空间矢量脉宽调制(SVPWM)、改进SVPWM和载波反向层叠调制(PODSPWM)算法的对比分析,说明了该算法对于抑制T型逆变器共模电压的优势与有效性,同时也指出了调制波移相PWM算法仍然存在的问题.%In vehicle electrical transmission and other high-power or higndensity AC speed regulating occasions,the impact and damage of common mode interference is particular prominent on the motor and speed regulating system.This paper analyzed the topology structure and working modes of the T-shaped inverter in details,achieves the cause of common mode voltage.We also deducted Fourier expression of common mode voltage and analyzed its harmonic components and mathematical meaning.Besides,we proposed a high frequency equivalent model of the T-type inverter with common mode interference capacity,simulation results of common mode voltage spectrum show that the model can reflect the actual status of the common mode current.Finally,a kind of modulation wave phase shift PWM algorithm that can eliminate common mode voltage was proposed.It shows that the new algorithm is more effective compared with traditional SVPWM,improved SVPWM and PODSPWM algorithm.And it also indicates the short comings of the modulation wave phase shift algorithm.