Control strategy of wide-load-range zero-voltage switch phase-shifted full-bridge converter

Abstract

The invention discloses a control strategy of a wide-load-range zero-voltage switch phase-shifted full-bridge converter. The control strategy comprises the following steps: S1, sampling a primary side current i of the wide-load-range zero-voltage switch phase-shifted full-bridge converter; S2, calculating a phase angle theta 1 between a turn-on moment of an auxiliary switching tube Q5 and a turn-off moment of a main switching tube Q1, and a phase angle theta 2 between the turn-on moment of an auxiliary switching tube Q5 and the turn-off moment of the main switching tube Q1; and S3, controlling the turn-on moments of the auxiliary switching tube Q5 and the auxiliary switching tube Q6 according to the theta in the step 2. Primary side current detection is introduced for control, and the auxiliary switching tubes Q5 and Q6 can be automatically switched on according to the relationship with the magnitude of the current, which means that the duty ratios of the auxiliary switching tubes Q5 and Q6 change along with the change of the current. Primary side current detection enables the auxiliary switching tubes Q5 and Q6 to be switched on in a self-adaptive mode in a full-load working condition, and the efficiency and stability of the converter are improved.

Description

technical field [0001] The invention belongs to the technical field of power electronics, and in particular relates to a control strategy of a zero-voltage switching phase-shifting full-bridge converter with a wide load range. Background technique [0002] The switching converter uses modern power electronic switching technology to control the on-off time of the switching tube and maintain a stable output voltage. Switching power supplies are generally controlled by pulse width modulation (PWM). With the development and innovation of power electronics technology, switching power supplies are becoming more and more perfect. The performance of the switching power supply is directly affected by the on-off control of the switching tube. Although it is under the same switching converter, but with different control methods, the output performance of the power supply is completely different, and even the power supply will be damaged. Traditional zero-voltage switching converters s...

AI Technical Summary

Problems solved by technology

However, the zero-voltage switching converter cannot be used well under light load conditions, because it is applied under light load conditions, that is, the load rate is less than 30%, and the traditional zero-voltage phase-shift full-bridge DC converter is under light load conditions. In this situation, the current of the primary side is too small to make the voltage of capacitor C3 or capacitor C4 drop to 0 volts, and it is not easy to realize the soft switching of the hysteresis bridge arm.

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