IMC-PID Control for Bidirectional Three-Phase AFE Rectifier for Reference Tracking and Disturbance Rejection Capability

This paper presents a simulation study to examine the internal model control-based proportional-integral derivative (IMC-PID) controller's performance implemented to the active front end rectifier (AFE) with reference tracking and disturbance rejection capability. The controller has been designed to control current and voltage in the d-q frame by implementing the inner and outer loop controllers using standard IMC-PID-based design procedures in each loop. However, the outer voltage loop exhibits initial sluggishness during the transient response because it has a pole lying on the origin; therefore, an active damping gain kf has been introduced at the outer voltage loop's feedback path to improve the design algorithm. In addition, during the initial state, the value of the control response to a step unit obtained using the standard IMC-PID-based procedure is K/Km, which has caused the output signal to oscillate. Therefore, multiplying the proportional part (P) of the PID controller with Km, the control response to a step unit starts at gain K, the maximum initial charging current needed to charge the capacitor. Simulation results show the controller performs good reference tracking and disturbance rejection, low total current harmonic distortion (THDi), low total voltage harmonic distortion (THDv), high power factor, and have the capability of bidirectional power flow.