Method and controller for inhibiting transformer dc magnetic bias

Abstract

This invention puts forward a method and a system for suppressing DC bias of a transformer and a power converter using said method and system, the input end of which is a full bridge structure, its output is a full wave commutation unit, energy is delivered from the input to the output via the transformer. The system includes: 1. a current sampling unit used in collecting the primary DC component of the transformer, 2. a controller connected with a current sampling unit which regulates work of the master circuit power switch element according to current samplings so as to suppress DC bias of the transformer.

Description

(1) Technical field [0001] The present invention generally relates to the field of power conversion, in particular to a system that needs to suppress the DC magnetic bias of a power transformer, and a converter using the system and method. (2) Background technology [0002] Power conversion circuits often convert a specific input voltage waveform into a specified output voltage waveform. In many applications, the input DC voltage needs to be converted into a required output DC voltage, which can be higher or lower than the input voltage. Typical applications of this type of converter are communication power supplies and computer power supplies. [0003] A full-bridge circuit structure system that is often used in current converters (such as figure 1 shown), which uses four controllable power switching elements (Q1~Q4, usually MOSFETs), a power transformer (T1, usually an isolation transformer), an output rectifier unit and an output filter (Lf and Co). Of course there is ...

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Problems solved by technology

However, the introduction of the air gap in this scheme will reduce the excitation inductance of the transformer, thereby increasing the excitation current in the transformer

This results in increased copper losses in the transformer primary, which is equivalent to an increase in the AC impedance of the transformer primary winding

Ultimately, the efficiency of the converter is not high

It can be seen that a small air gap is required for high efficiency, but a small air gap will make the transformer more prone to saturation

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