An Open-Circuit Fault Diagnosis for Three-Phase PWM Rectifier Without Grid Voltage Sensor Based on Phase Angle Partition

In order to accurately locate the open-circuit fault of power tube for three-phase PWM rectifier under the grid-voltage sensorless control strategy, an open-circuit fault diagnosis algorithm based on phase angle partitions of the current and voltage is proposed. To improve dynamic response for the system, predictive current control is implemented. The real-time change rate of the grid-current phase angle is utilized to determine whether a fault occurs. Based on the zero value platform in the grid-side distortion current generated by open-circuit faults, the corresponding phase angles for the grid current and the grid voltage are partitioned to locate the fault tubes. In a grid voltage sensorless control system, the grid voltage information obtained by the voltage observer and phase-locked loop can be susceptible to distortion or interference. To enhance the accuracy of phase-locked angle, a double generalized second-order integrator is used. The proposed open-circuit fault detection method can realize rapid diagnosis and location for single and double power tubes under grid-voltage sensorless predictive current control. Finally, experimental results are presented to verify the feasibility of the diagnosis method.