變頻器驅動之馬達端共模電壓抑制策略研究

INVESTIGATION OF STRATEGIES FOR SUPPRESSING COMMON-MODE VOLTAGE AT MOTOR TERMINALS IN VOLTAGE-FED PWM INVERTERS

近年來由於電力電子元件的切換速度加快，引發一些相關問題，其中尤以共模雜訊的影響最大。本文主旨即在探討由變頻器驅動的馬達，在馬達端所產生的共模電壓和共模電流問題，依系統的主要架構進行抑制方法研究，以期找出減少馬達軸心電壓的方法。本文並就目前可行的一些抑制方法，驗證其可行性，同時亦提出一種可達到抑制共模與差模電壓的被動式濾波器組合架構，結合分別針對共模電壓與差模電壓的濾波器，以達到消除此兩種雜訊的目的。由實驗得知本文所提架構不僅消耗功率較小，成本亦低，不失為一可行之架構。

This paper presents a comprehensive analysis for common mode noise induced at motor terminals. It causes motor shaft voltage to build up through electrostatic couplings between the rotor to the stator windings, rotor and frame, resulting in excessive bearing current. In addition, the common mode noise will induce a much larger common mode leakage current to flow into the ground via electrostatic coupling between the power cables, the stator windings and the ground frame. Existing strategies for these concerns will be studied to solve these serious problems including different PWM techniques and passive filter structures. Effectiveness and performance have been demonstrated by means of prototype case studies.