DELTA-SIGMA MODULATION FOR POWER CONVERTER CONTROL

摘要

A flyback converter is described that in some examples includes an integrated circuit that includes a delta-sigma converter and a cascaded integrator-comb filter configured to determine: a proportional factor, an integral factor, and a derivative factor associated with a secondary-side voltage across a secondary-side winding of the converter. The integrated circuit uses each factor to control a secondary switching element to perform synchronous rectification. In some examples, the flyback converter includes an auxiliary winding at the primary side of the transformer and a knee point voltage detection unit. The knee point voltage detection unit is configured to determine, based on an analog input indicative of a voltage at the auxiliary winding, an integral of value and detect, based on the integral value, a knee point voltage associated with the voltage at the auxiliary winding. A controller may use the detected knee point to control a primary side switch.

主权项

1. A method comprising:
receiving, by an integrated circuit, one or more analog inputs indicative of a secondary-side voltage across a secondary-side winding of a transformer of a flyback power converter; converting, by a delta-sigma converter of the integrated circuit, the one or more analog inputs into a digital bit stream indicative of the secondary-side voltage; determining, by a cascaded integrator-comb filter of the integrated circuit, a proportional factor associated with the digital bit stream, an integral factor associated with the digital bit stream, and a derivative factor associated with the digital bit stream; and controlling, by the integrated circuit, a synchronous rectification switching element coupled to the secondary-side winding of the flyback power converter based on the proportional factor, the integral factor, and the derivative factor.