SIMPLE OPEN-LOOP CONTROL FOR INTERMEDIATE DC Bus CONVERTERS

摘要

A simple open-loop primary side control for bridge-type isolated intermediate bus converters is presented. The control is based on the integration of a fixed 50% duty cycle oscillator with either one or two 100V half-bridge drivers to deliver complete primary side control and drive solution. In this scheme switching frequency and dead time between the low side and high side pulses is adjustable in order to fit various applications, power levels, and switching devices. An innovative current limit scheme was implemented that further reduces complexity and space requirements of the overall system solution. Finally, the controllers can be easily synchronized to an external clock in a wide frequency range. Using these new controllers, simple and low cost 48V DC bus converters were designed to deliver 160W to 240W with 96% efficiency. This is 2-4% higher efficiency than conventional, fully regulated, board mounted power converters, and was achieved with up to 50% smaller board size.