PWM逆变器端过电压滤波器设计

PWM逆变器通过长线电缆与电机连接时,由于电缆分布参数的影响会在电机端产生2倍的过电压,从而使电机承受的应力大为增加.本文在对电压脉冲上升时间与电缆长度关系分析的基础上,提出了一种改进型的逆变器端无源滤波器.通过对滤波器传递函数特性分析,给出了具体的参数选取原则与设计方法.采用本文提出的滤波器可以使电机端的过电压得到对称的抑制,通过在380 V/3 KW电机系统的实验,验证了该滤波器的有效性,取得了良好的效果.

Design of over-voltage filter at PWM inverter output terminals

The voltage at motor terminal would be double because of the effects of cable distributed parameters when motor is fed with PWM inverter through a long cable therefore resulting in a heavy stress on motor. In this paper, an improved passive filter structure installed at inverter terminals is proposed on the basis of analyzing the relationship of the rising time and the length of cable. The principle for the selection of parameters and detailed design procedure are given. The over-voltage at motor terminal could be mitigated symmetrically by the proposed filter. The validity of the proposed filter is supported by the experimental results which is taken on a 380V/3KW motor system.