High-voltage DC power conditioner

Modern radar systems, particularly mobile systems, require high-quality, compact, lightweight, dc power sources. High frequency (e.g., 10-kHz) power conditioners have been used to obtain the desired qualities. By adapting a variation of the series inverter circuit, liberally infused with artificial line-type pulse modulator technology, an effective, simple, and high-performance technique has been devised. Low-frequency (50- to 400-Hz) transformers are eliminated by direct full-wave rectification of the ac power source. (With appropriate input filter design, power source frequencies from 50 to 400 Hz can be accommodated in one design.) A pair of suitable high-frequency thyristors alternately charge and discharge a pair of capacitors through the primary of a pulse power transformer. Since the effective frequency is high (thousands of hertz), the transformer and load filter capacitor are small compared to the equivalent normal power frequency components. Operating Q is low (approaches one), minimizing the reactive power. Regulation of the output voltage is achieved by varying the pulse recurrence frequency: from as low as zero to some maximum (e.g., 20 kHz). No-load to full-load regulation <½ percent has been demonstrated. The circuit is not harmed by overload, and has a current fold-back feature. Normal operation resumes automatically when an overload is removed.