20 kW inverter flyback charging system

A 20 kW inverter flyback charging system has been developed and produced for the ARSR-3 air route surveillance radar system. This precision regulated charging system is used in the transmitter to charge the PFN in a 14- megawatt peak power modulator to over 3,000 volts. The technique used completely eliminates the need for the con­ ventional regulated, high voltage power supply and the dissipative tube-type shunt regulator used in older line type modulators. The circuit stores a measured amount of energy in a transformer in proportion to transformer in­ ductance and current flow (E = 1/2LI2), and then transfers this energy to the PFN with the resulting voltage being pro­ portional to PFN capacitance (E = 1/2CV2). This is ac­ complished by utilizing two banks of 36 parallel connected transistors, in conventional T0-3 packages, to switch cur­ rents in excess of 500 amps.