Fault Diagnosis of Current Sensor in Grid-Connected Inverter Based on Sliding Mode Observer

In the grid-connected inverter, the current sensor is easily affected by various faults, which reduces the reliability. In the conventional current sensor fault diagnosis method, misjudgment will occur when the current step changes as only the residual error between reference current and the sampled one is used as the fault flag. To solve this problem, in this paper, the current space vector error projection is used as the correction term to reconstruct the fault phase current using a sliding mode observer. Then, the average absolute value of the residual error between reference current and the sampled current, and the average absolute value of the residual error between reconstructed current and the sampled current are used to diagnose the fault of the current sensor. As a result, misjudgment due to the step change of the current can be avoided. Finally, the feasibility of this method is verified on the Matlab/Simulink platform.