A relay type llc resonant topology circuit and switching power supply

Abstract

The invention discloses a relay type LLC resonant topological circuit, which comprises a transformer, a primary side LLC resonant circuit and a secondary side circuit. The primary side of the transformer contains two primary windings, and the primary LLC resonant circuit controls the two primary windings to alternately flow current in the same direction during operation, that is, the current on the primary winding of the transformer changes in one direction, thereby reducing the Electromagnetic noise reduces the difficulty and cost of EMC optimization of the circuit; moreover, the directions of the magnetic fields generated by the two primary windings when the current flows in are opposite, that is, the hysteresis loop of the transformer works in the first quadrant and the third quadrant, and the magnetic core uses The rate is higher. The invention also discloses a switching power supply, which has the same beneficial effects as the above topological circuit.

Description

technical field [0001] The invention relates to the field of switching power supplies, in particular to a relay type LLC resonant topology circuit and a switching power supply. Background technique [0002] At present, the basic topological circuits commonly used in switching power supplies include: flyback topological circuits, forward topological circuits, push-pull topological circuits, half-bridge topological circuits, full-bridge topological circuits, etc. From the perspective of core utilization: the hysteresis loop of the transformer in the flyback topology circuit and the forward topology circuit only works in the first quadrant, resulting in low core utilization; while the push-pull topology circuit, semi The hysteresis loop of the transformer in the bridge topology circuit and the full bridge topology circuit works in the first quadrant and the third quadrant, and the utilization rate of the magnetic core is high. However, the current on the primary winding of the...

AI Technical Summary

Problems solved by technology

However, the current on the primary winding of the transformer in the push-pull topological circuit, half-bridge topological circuit and full-bridge topological circuit changes in positive and negative directions, that is, the range of current variation is -I MAX ~I MAX , which leads to the fact that in the core power circuit of the switching power supply, at the same switching speed, the current variation range is 0~I MAX 2 times that of the circuit, resulting in greater electromagnetic noise, thereby increasing the difficulty and cost of the optimization of the circuit's EMC (Electro Magnetic Compatibility, electromagnetic compatibility)

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