Transistor Inverter Design Optimization in the Frequency Range Above 5 kHz Up to 50 kVA

Different aspects of the design of inverters for industrial applications including static power supplies, light welding equipment, and high-speed motor control at input voltages from 30 to 300 V are described. High frequencies (5-30 kHz) are used at power levels between 1 and 50 kW, and emphasis is placed on minimization of losses in order to obtain efficient and compact systems. Attention is given to optimization of snubber technology for low switching losses and feedback of the snubbing power to the supply at the larger powers, design aspects of large ferrite transformers, as well as protection of the equipment. The on-voltage of the Darlington switches is reduced by adding a compensation voltage source to the base of the main transistor, thus lowering on-losses drastically. Experimental results obtained from 1-kVA, 6-kVA, and 50-kVA single-phase units are used to highlight certain aspects of the inverter design principles.