Combinational-logic-based traction inverter fault diagnosis

This paper presents a combinational-logic-based approach for identifying faults that could occur in power electronic components of an electric vehicle inverter. A real-time simulation model of an electric vehicle is used to study the behavior of available sensor signals and control commands, with specific measured quantities, during vehicle operation. Those quantities could be, but are not limited to, mean values of the phase currents, DC bus current, and traction motor speed (if available), in addition to control command quantities. Those quantities carry information of offsets and disturbances that could occur under faulty operating conditions compared to nominal operation. They are thus observed and studied under nominal conditions and then when a fault is injected. Finally a methodology is developed using these observations based on simple combinational logic to diagnose a fault occurring at any time during a vehicle drive cycle. The proposed method is presented and validated by real-time simulations to capture four different power electronics faults injected at different drive cycle times. Results show that the proposed method is able to diagnose different faults irrespective of when would they occur. The method can be extended to diagnose electric machine, sensor, and transmission faults.