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This paper focuses on the high-frequency leakage current flowing through the grounded heat sink of a voltage-source pulsewidth-modulation (PWM) inverter in an adjustable-speed motor drive system. A passive electromagnetic interference (EMI) filter is proposed, designed, and tested for a 200-V 3.7-kW drive system. This filter does require access to the ungrounded motor neutral point. An equivalent common-mode circuit for the drive system equipped with the EMI filter is derived from experimental waveforms along with theoretical discussions. Experimental results verify that the EMI filter is viable and effective in eliminating both heat-sink and motor-frame leakage currents from the drive system. Index Terms--Common-mode voltage, electromagnetic interference (EMI), inverters, leakage current, motor drives, shaft voltage.

This paper deals with integrating a small-sized passive electromagnetic interference (EMI) filter with a voltage-source pulse-width modulated (PWM) inverter. The purpose of the filter is to eliminate both high-frequency common-mode and normal-mode voltages from the three-phase output voltages of the inverter. A laboratory system consisting of a 5-kVA inverter, a 3.7-kW induction motor, and a specially-designed passive EMI filter was constructed to verify the viability and effectiveness of the filter. As a result, both line-to-line and line-to-neutral output voltages look purely sinusoidal as if the inverter were an ideal three-phase variable-voltage, variable-frequency power supply when viewed from the motor terminals. This results in a complete solution to serious EMI issues related to high-frequency common-mode and normal-mode voltages produced by the PWM inverter. Index Terms--Common-mode voltage, electromagnetic interference (EMI) filters, shaft voltage, three-phase voltage-source pulse-width modulated (PWM) inverters.

This paper proposes a small-sized passive electromagnetic interference (EMI) filter for the purpose of eliminating high-frequency shaft voltage and ground leakage current from an ac motor driven by a voltage-source pulsewidth-modulation inverter. The filter requires access to the neutral point of the motor. A common-mode inductor is connected between the inverter and the motor. The neutral point of the motor is connected to the dc-bus midpoint via a resistor. The dc-bus midpoint is created by using two capacitors in series across the dc positive and negative buses. This unique circuit configuration makes the common-mode inductor effective in reducing the common-mode voltage appearing at the motor terminals. The validity and effectiveness of the EMI filter is verified by experimental results obtained from a 5-kVA laboratory system. Index Terms--Common-mode voltage, electromagnetic interference (EMI), ground leakage current, inverter-driven motors, shaft voltage.

This paper proposes a small-sized passive EMI filter for the purpose of eliminating high-frequency shaft voltage and ground leakage current from an AC motor. The motor is driven by a general-purpose PWM inverter connected to a three-phase grounded voltage source. The passive EMI filter requires access to the ungrounded neutral point of the motor. This unique circuit configuration makes the common-mode inductor effective in reducing the high-frequency common-mode voltage generated by the PWM inverter with a carrier frequency of kHz. As a result, both high-frequency shaft voltage and ground leakage current can be eliminated very efficiently. However, the common-mode inductor may not play any role in reducing the low-frequency common-mode voltage generated by the diode rectifier, so that a low-frequency component still remains in the shaft voltage. Such a low-frequency shaft voltage may not produce any bad effect on motor bearings. The validity and effectiveness of the EMI filter are verified by experimental results obtained from a 200-V 5-kVA laboratory system. © 2007 Wiley Periodicals, Inc. Electr Eng Jpn, 159(2): 80–87, 2007; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/eej.20243 [ABSTRACT FROM AUTHOR]

This paper deals with an inverter system integrating a small-rated passive EMI filter with a three-phase voltage-source PWM inverter. The purpose of the EMI filter is to eliminate both common-mode and normal-mode voltages from the output voltage of the inverter. The motivation of this research is based on the well-known fact that the higher the carrier or switching frequency, the smaller and the more effective the EMI filter. An experimental system consisting of a 5-kVA inverter, a 3.7-kW induction motor, and a specially designed passive EMI filter was constructed to verify the viability and effectiveness of the EMI filter. As a result, it is shown experimentally that both three-phase line-to-line and line-to-neutral output voltages look purely sinusoidal as if the inverter system were an ideal variable-voltage, variable-frequency power supply when viewed from the motor terminals. This results in complete solution of serious issues related to common-mode and normal-mode voltages produced by the inverter. © 2003 Wiley Periodicals, Inc. Electr Eng Jpn, 145(4): 88–96, 2003; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/eej.10206 [ABSTRACT FROM AUTHOR]