Super-Twisting Algorithm-based Sliding Mode Observer for Open-Circuit Fault Diagnosis in PWM Voltage Source Inverter in an In-Wheel Motor Drive System

To enhance the reliability of in-wheel motors, it is crucial to avoid failures in the motors, sensors and the motor drives. However, in-wheel motor structures formed on permanent magnet synchronous motors (PMSMs) and voltage source inverter (VSI) using pulse-width modulation (PWM) are fragile to power-converter component faults such as power switches. Furthermore, switching device faults accrue in the form of open circuits or short circuits. An open circuit fault imposes phase voltage imbalances to each phase voltage. This paper presents a new approach to detect the imbalanced phase voltage due to the open-circuit fault in the inverters employing a super-twisting algorithm-based sliding mode observer. The combination of proposed observer with the Extended Kalman filter (EKF) results in a robust observer which can be used under the noisy measurement conditions that are unavoidable in industrial applications. In addition, the simulated observer applies a model-based fault detection algorithm, enabling the fault to be isolated more easily and reliably than when using signal processing methods.