Fault Tolerant Online Condition Monitor of DC-Link Capacitor for Open-end Winding Machine

This paper proposes and experimentally assesses an online capacitor condition monitoring algorithm for use with a drive system using an open-end winding topology. The proposed algorithm periodically evaluates the dc-link capacitance during a capacitor discharging state when the motor is at standstill. Expressions of capacitor voltage and current are derived for discharging cycle and provide key information for capacitance estimation using a recursive least square method. Also, the operation range of the proposed algorithm is extended to multiple insulated gate bipolar transistor failure conditions in the inverter. Experimental results verify that the proposed algorithm is capable of identifying capacitor deterioration from both healthy and postfault state for a 3010 uF capacitor (450V 9.8A). but the estimation accuracy is reduced for 438 uF capacitor (385V 2.7A).