抑制共模电压的不对称NZPWM技术

为了抑制共模电压,消除死区效应导致的共模电压尖峰,提出了一种可通过软件实现的不对称无零矢量脉宽调制技术。在对已有技术进行分析的基础上,调整了开关次序,并对有效矢量的作用时间作了限制。利用不对称的矢量合成算法,弥补最小作用时间限制导致的电压畸变。实验结果表明:该算法可以完全消除死区效应导致的异常脉冲尖峰,从而将共模电压幅值抑制到普通算法的三分之一。因此,该方法具有较好的有效性和实用性。

Asymmetrical NZPWM technique for reducing the common-mode voltage

With pulse width modulation(PWM)in voltage source inverters,the high frequency and high amplitude common-mode voltage(CMV)may seriously affect the motor drive system.The common mode voltage can be restrained with nonzero vector PWM methods(NZPWM).An asymmetrical NZPWM technique was developed to reduce CMV and eliminate CMV peaks.The switching sequence differs from exiting methods,and the minimum duty-ratio of the effective space vector is limited.An asymmetrical composing method for the space vector was used to prevent distortion of the reference voltage vector.The peak-to-peak value of CMV can then be restrained to one third of that in traditional PWM,even with the dead-time effect.Simulations and experiments show that the method effectively reduces CMV.