On-board electric vehicle battery charger drawing sinusoidal current at unity power factor - uses high frequency converter with pulse width modulation to switch rectifier-transformer primary circuit

摘要

The converter (AA), interposed between the single phase or three-phase mains supply (Sv) and the rectifier-transformer (TR) primary (P1,P2), contains series (Ta) and shunt (Tb) connected transistor switches, opened and closed alternately by the controller (CD), the pulse width varying with the supply voltage (Ve). Short-circuit current is limited by locally augmenting the system impedance (L). The controller produces appropriate pulses by comparing a saw-tooth waveform, internally generated at, e.g. 50 kHz, with the 50 Hz supply waveform (Ve), and so applies them to the converter switches so that the current (I) supplied by the source (Se) is always of the same frequency as the source voltage, and in phase with it. Several variants are described. USE/ADVANTAGE - Esp. for on-board chargers for electric vehicles. Compact, with good waveform and power factor, optimising charge time.