A DC-Link Hybrid Active Discharge Scheme for Traction Inverters

when an Electrical Vehicle (EV) encounters an accident or the vehicle is taken to a service station, the DC-link capacitor in the inverter must be discharged to ensure safety of both the passengers and the operator. This paper examines the limitations of traditional discharge techniques and proposes a novel hybrid discharge solution that combines the existing winding-based discharge method with a flyback converter. The proposed technique enhances redundancy, decreases the discharge time and minimize the risk of DC-link voltage overshoot during the regeneration action caused by quadrature axis current injection. The study introduces a low-voltage discharge circuit enabled by a flyback converter using MOSFET in linear mode, presenting two distinct approaches. The paper includes a simulation comparison of winding-based discharge with the proposed Hybrid discharge technique. The proposed solution has a higher discharge rate and reduces the voltage overshoot on the DC-Link capacitor. The proposed hardware is verified using the simulation and experiments conducted on a high voltage supply test rig.