An improved inverter output filter configuration reduces common and differential modes dv/dt at the motor terminals in PWM drive systems

In this paper, an improved inverter output filter is proposed for pulsewidth-modulated (PWM) drive systems. The proposed filter is shown to effectively reduce both the differential and common modes dv/dt at the motor terminals, even in the presence of long motor leads. Reducing differential mode dv/dt reduces overvoltages at the motor terminals and lowers the stress on the motor insulation. Lowering common mode dv/dt is shown to significantly reduce high-frequency leakage currents to ground and induced shaft voltage in the motor. An important advantage of the approach is that the filter can be installed within the inverter enclosure to achieve both the differential and common modes dv/dt reductions at the motor terminals. Thus, the use of the filter can contribute to enhanced bearing life and improve reliability of PWM drive systems. Analysis, design equations, and experimental results on a 480-V 20-hp PWM drive system are presented. The filter configuration is an excellent candidate for many new and retrofit PWM 480-V/575-V drive systems.

[1]  A. H. Bonnett,et al.  Analysis of the impact of pulse-width modulated inverter voltage waveforms on AC induction motors , 1994, Proceedings of IEEE Pulp and Paper Industry Conference.

[2]  Doyle F. Busse,et al.  System electrical parameters and their effects on bearing currents , 1997 .

[3]  T. Lipo,et al.  Elimination of common mode voltage in three phase sinusoidal power converters , 1996, PESC Record. 27th Annual IEEE Power Electronics Specialists Conference.

[4]  Y. Murai,et al.  Leakage current reduction for a high-frequency carrier inverter feeding an induction motor , 1992 .

[5]  Doyle F. Busse,et al.  The effects of PWM voltage source inverters on the mechanical performance of rolling bearings , 1997 .

[6]  Alfio Consoli,et al.  Induction motor modeling for common mode and differential mode emission evaluation , 1996, IAS '96. Conference Record of the 1996 IEEE Industry Applications Conference Thirty-First IAS Annual Meeting.

[7]  A. von Jouanne,et al.  Design considerations for an inverter output filter to mitigate the effects of long motor leads in ASD applications , 1997 .

[8]  H. Akagi,et al.  Modeling and damping of high-frequency leakage currents in PWM inverter-fed AC motor drive systems , 1995, IAS '95. Conference Record of the 1995 IEEE Industry Applications Conference Thirtieth IAS Annual Meeting.

[9]  A. von Jouanne,et al.  Application issues for PWM adjustable speed AC motor drives , 1996 .

[10]  Prasad Enjeti,et al.  A new approach to improve power factor and reduce harmonics in a three phase diode rectifier type utility interface , 1993, Conference Record of the 1993 IEEE Industry Applications Conference Twenty-Eighth IAS Annual Meeting.