Lightweight, compact, on-board, electric vehicle battery charger

摘要

An onboard electric vehicle charger is provided which incorporates a forward converter with dynamic balancing of the primary drive currents of its ferrite core transformer to produce 5,000 watt charging power with a power density of 333 watts per kilogram and full safety isolation between the input power source and the batteries plus small size (approximately 15 by 9 by 6) and weight (less than 15 kilograms) and a power factor correcting boost preregulator with dynamic adjustment of its compensation networks which produces full correction to substantially unity (99.9%) for power factor with current total harmonic distortion (THD) of 2% to 3% over the entire power range of 100 watts to 5,000 watts. The same boost preregulator circuit allows operation from power sources of 95 to 145 VAC or 200 to 275 VAC. The combination of the boost converter, (boost preregulator) and forward converters with the invention's control scheme enables constant throughput (in watts) during each step of the charging process and a constant pulse width modulation (PWM) duty cycle near maximum at all power levels by varying the output voltage of the boost preregulator in direct relation to the power level. A second forward converter, using the same dynamic balancing of primary currents utilized in the main forward converter described works with the boost preregulator described to permit integration of a DC to DC converter function with 1 KW (75 A 14 VDC) capability plus full safety isolation between the high voltage propulsion batteries and the auxiliary (12 volt) electrical system of the vehicle.