High Efficiency and High-Power Quality Modulation Strategy for Single-Stage Electrolytic Capacitor-less On-board EV Charger

This article presents a modulation scheme for achieving high-efficiency and high-power quality based on the secondary duty cycle and the phase shift for a single-stage electrolytic capacitor-less bidirectional onboard charger. Zero voltage switching is achieved for all switches for wide voltage range operation based on an optimized duty cycle which increased the efficiency of the converter. Meanwhile, high power quality is guaranteed by a varying phase shift which is directly generated by a controller. To validate the proposed modulation scheme, experimental results from the 3.7kW onboard charger are provided at 1kW power showing an improvement of 0.4% over the conventional method. Furthermore, the efficiency of the converter is improved by 3% at low battery voltage where zero voltage switching is severe while using the conventional method.