Modified repetitive control design for two stage off board Electric Vehicle charger

Abstract

In this paper, a three-phase, two stage, bidirectional off board plug-in Electric Vehicle (PEV) charger controller has been designed and implemented in real time. The proposed PEV charger is able to work in all four quadrants in active–reactivepower plane. Generally, power electronics converters are controlled by PI regulators in d-q reference frame, where the signals to be regulated are inherently DC in nature. These controllers are implemented in two loops i.e., Slow (outer) control loop and fast (inner) control loop. Setting the gains of outer loops are little bit easier in comparison to fast acting inner loops besides the involvement of decoupling terms to have independent operation of active and reactive current components. Therefore, a repetitive controller (RC) is designed to regulate the inner sinusoidal reference current having both active–reactive​ components as per the control requirement without involving any decoupling terms. The RC is well known for their ability to track periodic signal and inherently based on internal model control theory. However, the major problem with RC is its sensitivity due to which it provides high gains at all frequencies levels. Therefore, in proposed controller the sensitivity of RC is modified by squaring it. This results the deep notches at higher frequency levels This approach is found to be very much suitable for the compensation of reactive power and load current harmonics. This also helps to exclude unwanted frequencies which results reduction in THD level. Therefore, the main contribution of this paper is adapting such robust EV charger controller for harmonic compensation. Moreover, from the implementation, it is found that the conventional RC is capable to compensate load current harmonic to some extent but it takes around 140 μs computational time. However, the proposed RC takes around 100 μs computational time, this results the grid current purely sinusoidal. The MATLAB/Simulink environment has been used to simulate proposed PEV charger controller, further it has been verified on scaled down experimental prototype.