An Improved Combined Current Control for Single-Phase Operation Mode of Single- / Three-Phase EV Charging System with Voltage Ripple Suppression

In this paper, the control stage of an interesting versatile single-/three-phase electric vehicle (EV) charging system is studied in details. Therein, a typical three-phase two-level voltage source rectifier can be reconfigured to operate as a single-phase rectifier where two phase-legs operate with a PWM interleaving method and the grid neutral is connected to the midpoint of the DC-bus capacitors with the third leg operating as an active power decoupling (APD) circuit to reduce the current stress in the capacitors. To improve the performance of the single-phase operation while considering external grid voltage disturbances, firstly, an improved hybrid current control method combining deadbeat prediction current control (DPCC) with repetitive control (RC) is proposed in this paper, where a modified RC is adopted to suppress the influence of the internal DC-bus capacitor voltage disturbance and to improve the harmonic control performance. Thereafter, via introducing the weighting factor K f of the DPCC and by multiplexing the filter of RC in the DPCC output, the stability of the current loop under the influence of grid voltage distortion and grid impedance can be improved remarkably. Moreover, a grid-frequency voltage ripple suppression function implementing Zero-Voltage-Switching (ZVS) turn-on for the APD circuit is achieved, improving the reliability of the converter. Finally, a 7.4 kW single-phase AC-DC converter prototype is built to verify the feasibility and effectiveness of the proposed method in the single-/three-phase EV charging system.