Texas Instruments (cork) Limited

Commergy Technologies Limited

Peter Michael Meaney

George Young

Andrew Bernard Keogh

William James Long

Seamus Martin O'Driscoll

This invention relates to a control circuit for a buck power factor correction (PFC) stage. Buck PFC stages are commonly used in low cost, high efficiency power converters. These buck PFC stages are typically controlled using a very slow control loop with a crossover frequency of the order of 10 to 20 Hz. However, such a slow response is unsuitable for applications requiring overvoltage protection. The present invention overcomes the problems with the known control circuits for buck PFC stages by implementing a two stage control circuit having a fast outer loop control circuit and a slow inner loop control circuit. The fast outer loop control circuit is in operation during low load conditions and the slow inner loop control circuit is only active under load.

Control circuit for a buck power factor correction stage

A heavy duty cycle power converter () has current mode control in which the closed loop control is carried out by a controller () using a desired signal () which is a function of the difference between the desired duty cycle () and the measured duty cycle (). This fluctuates current mode control without voltage feedback.

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Cloyne, Ireland

Peter Michael Meaney