High Frequency, High Power, Off-Line Switching Converters

Abstract

Power Converters with pawer through-put greater than 3KVA tend to operate from three phase input supplies. The magnitude of the three phase line to line voltage varies from country to country and can be as high as 480 Volts 50/60Hz. If allowance is made for line regulation, the DC bus voltage at high line can extend to 750 Volts. This would normally imply the use of 1000 Volt transistors - Bipolar or Mosfet. When used correctly, four Modules rated at 500 Volts, can be demonstrated to deliver output powers in excess of 9kW without resorting to the parallel connection of Modules. Paralleling modules can increase these power levels considerably. Converters of such power levels are frequently required for use in UPS, Induction Heating, Welding and Railway battery-charger systems. High Frequency Switchmode techniques can dramatically reduce the mass of these systems while offering several benefits of a secondary nature.