A Filter-Less EMI-Free Power Converter Using a Diode-Clamped Linear Amplifier

This paper proposes a new power converter for motor drive systems without any ac inductor nor EMI filter. The main circuit of the proposed circuit consists of a diodeclamped linear amplifier (DCLA) and a dc-voltage equalizing circuit. The dc-voltage equalizing circuit consists of a series-connected switched capacitor converter enabling to use a diode rectifier as its power supply. A zero-sequence voltage control method is introduced to expand the output voltage range as well as to reduce the theoretical power loss caused by an active-state operation. As a result, experimental results exhibit a high efficiency of 94.7% and a low conductive EMI emission adequate to meet the IEC61800-3 Category C1.