Input Power Quality Control of Integrated On-Board Charger with Reduced DC-link Capacitance

An integrated on-board charger uses the motor drive and its voltage source converter for battery charging when the vehicle is not running. This charger in AC-DC conversion stage has an inherent tendency to produce low frequency voltage ripple in both DC-link and split DC-link capacitor voltages. Therefore, bulky high valued electrolytic capacitors are adopted to absorb these low frequency capacitor ripples. Replacing these electrolytic capacitors with low valued film capacitors, results in poor input power quality. Therefore, this paper presents a control strategy based on modified unit-template control with reduced DC-link capacitance value to achieve improved input power quality without using any additional active/passive components. In modified unit-template control, the harmonics information of the grid current is feed-forwarded into the unit template to achieve unity power factor operation and reduced grid current THD. Furthermore, to reduce the influence of double frequency component on EV current/voltage, a DC-link feedforward control is implemented in DC-DC stage. Finally, the effectiveness of the solution presented in this paper, is verified by simulation and experimental results.