Electric Drive System Over-Voltage Protections for Electric Vehicles

摘要

System over-voltage protection is one of the most critical design criteria in electric vehicle applications.rnElectric vehicles with permanent magnet motor drives may experience over-voltage under certain faultrnconditions. Such scenario exists when the main contactor that connects the energy source, such as arnbattery source, to the electric drive system is opened due to a functional failure while the electric machinernis operated in generating mode.rnThere is a need to thoroughly investigate the system over-voltage transient behaviours under variousrnsystem operating conditions during the event that the main contactor is suddenly opened. To investigaternsuch system transient behaviours, building a system transient model is a necessity. This modelrnneeds to be validated with real system testing. Once the model is validated, it will be used to identifyrnthe worst case over-voltage situations under various system operating conditions.rnThis paper presents the investigation results on the system over-voltage transient behaviors underrnvarious system operating conditions. An electric drive system is modeled in Matlab/Simulink. Thisrnmodel is validated with dynamometer test results on a 100kW electric drive system for electric vehiclernapplication at various operating points. The model is then used to investigate the initial voltage rise raternin generating mode, the over-voltage protection response time, and the second rebounce voltagerntriggered when the over-voltage protection is cancelled. The model is also used to investigate thernrebounce voltage triggered by an under voltage shutdown in motoring mode. The simulation results arernused as the basis in system over voltage protection design.