Phase shifted full bridge zero voltage switching converter

Abstract

The invention relates to a phase-shift full-bridge zero-voltage switch converter. The main circuit of the converter comprises an input direct-current power supply, a full-bridge inverter circuit, a transformer, an uncontrolled rectifier circuit and a filter output circuit. The switch converter is characterized in that an active clamping circuit of a transformer primary side is arranged in the full-bridge inverter circuit and includes two clamping switching tubes (Q5 and Q6) and a resonant capacitor or a power resistor. In the full-bridge circuit, the two clamping switching tubes (Q5 and Q6) forms a new pair of bridge arms; and the connection point between the two clamping switching tubes (Q5 and Q6) is connected between the transformer primary side and an inductor (Lr) of the full-bridge inverter circuit by the resonant capacitor or power resistor. According to the invention, in the full-bridge inverter circuit of the primary side of the transformer, a new circuit topology is formed by the clamping switching tubes, so that the defects of a secondary side clamping circuit can be overcome and problems that the existing primary side clamping conduction loss is high and the conduction efficiency can not be effectively improved can be solved.

Description

technical field [0001] The invention relates to a phase-shifting full-bridge zero-voltage switching converter, in particular to a primary-side active clamping circuit therein. Background technique [0002] At present, the State Grid Corporation is vigorously promoting the development of electric vehicle charging stations, and the development of power batteries requires the follow-up of high-power electric vehicle chargers. Due to its many advantages, the phase-shifted full-bridge zero-voltage switching converter has been widely used in medium and high-power power supplies. This circuit topology output rectifier diode is hard-switched on and off, which brings voltage spikes and increases EMI interference. At present, a lot of research is to add clamping diodes on the primary side or the secondary side, and the position of the clamping is different. In summary, there are the following: [0003] (1) Add clamping diodes on the primary side, which are divided into two types: tra...

AI Technical Summary

Problems solved by technology

The disadvantage of this circuit is that when the output voltage is very high and the output is short-circuited, due to the L f Larger, plus the energy on Cr, the impact current on D9 is too large at the moment of short circuit, exceeding the current range that D9 can withstand, and it is easy to damage the D9 diode

In addition, when the primary side switch tube is turned on, the secondary side needs to charge Cr, which causes the inrush current of the primary side switch tube to be too large. When the clamping capacitor Cr is clamped, the current on the output inductor is provided by Cr and is not fed back to the primary side. As a result, the primary switching tube loses the zero voltage condition beyond the forearm Q1 and Q3

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