TRANSFORMER COMMUNICATION SYSTEM

摘要

This invention generally relates to methods for transferring information between primary and secondary sides of a switched mode power converter (SMPC), and more particularly a flyback or forward converter operating in discontinuous current mode. An SMPC has an isolation transformer for power transfer from a primary side to a secondary side of the SMPC and has a communication circuit for data communication between the primary side and the secondary side, the SMPC comprising: the transformer having a primary winding and a secondary winding; a primary switch coupled in series with the primary winding; and a primary switch controller configured to control each of a first and a subsequent power transfer cycle of the SMPC by controlling the primary switch ON for an ON time period to allow a first energy transfer from the input to the transformer and then controlling the primary switch OFF for an OFF time period such that energy is transferred from the transformer to the output circuit, wherein the primary switch controller is configured to control the ON time period of the subsequent power transfer cycle to start at a time delay after the end of the OFF time period of the first power transfer cycle, wherein the communication circuit comprises: a transmission winding and a reception winding magnetically coupled to the transmission winding, wherein one of the transmission winding and the reception winding comprises the secondary winding of the transformer and the other one of the transmission winding and the reception winding is on the primary side of the SMPC; a communication switch coupled in series with the transmission winding; a communication controller to control the communication switch to allow charge flow through the transmission winding during at least part of the time delay; and a detector coupled to receive a signal from the reception winding to thereby detect data transmitted from the transmission winding, said signal indicating the charge flow through the transmission winding.