A novel approach to the design of a transistorized inverter- converter operating at higher-than-audio frequencies

In this paper we describe some of the design and operating characteristics of an unusual 5-Kw 25kHz transistorized invertor- convertor, in which the high-power switch consists of a series arrangement of low-power transistors. The dc voltage is obtained from the three-phase line by voltage tripling rectification in each phase, thus avoiding a 60-Hz transformer. The resulting supply is exceptionally compact, light weight, and inexpensive. In contrast to most solid-state circuits, this supply is found to be extremely resistant to reactive voltage `spikes' attendant to the excitation of inductive loads. We also discuss the advantage in reliability resulting from the series arrangement of the transistors.