A low-inductance DC bus capacitor for high power traction motor drive inverters

For a battery-powered traction motor drive, the inverter DC bus presents high-frequency pulsating current due to device switching. Conventional inverter design sizing DC-bus capacitor based on voltage ripple is no-longer effective. In order to handle high current in a high temperature environment, a low-inductance high-current film capacitor is proposed to replace the conventional electrolytic bulk capacitors for a 75 kW traction motor drive inverter. The proposed design results in significant size reduction and performance improvement over the existing one. Characteristics of the low-inductance high-current film capacitor are presented to show its superiority to the conventional electrolytic capacitors. Experimental results are shown to verify the need of the proposed capacitor.