PWM逆变器供电异步电机端部过电压的分析和仿真

PWM逆变器供电时电机的端电压出现幅值增高和振荡现象,对电机的匝间绝缘造成很大的威胁,本文提出了一种可以判断PWM逆变器供电异步电机端部过电压波形的实用仿真方法,该方法根据PWM逆变器供电电机系统的特征建立系统的仿真模型,将电机用实测的等效的阻抗频率特性来替代,将三相电缆等效成一个二端口网络,通过傅立叶分析计算电机端部的暂态过电压。与实测波形的对比,证明这种方法的仿真结果可以与实际情况良好地吻合。

Analysis and Simulation of Terminal Overvoltage for PWM Inverter Fed Asynchronous Machine

The PWM inverter power supply may cause motor terminal voltage surge and rising which results in heavy electric stress on interturn insulation of motor windings. This paper introduces an effective method to determine the terminal voltage waveform of the motor fed by PWM inverter. Based on the features of the PWM inverter fed motor system , the simulation model is established. The motor is represented by an equivalent impedance frequency characteristic, so that the analysis of inner complicated electromagnetic couplings of motor under high frequency can be avoided. The three-phase connecting cable is then reduced to a two-port network. With Fourier analysis, the transient overvoltage at motor terminal is calculated.Examples of the PWM fed motor terminal overvoltage calculated by using this method and the comparison of calculated result with experimental result are also given in the paper.