A Method of Improving the Dynamic Performance of Synchronous Rectification Primary Side Feedback Flyback Power Supply

Abstract

The invention discloses a method for improving the dynamic performance of a synchronous rectification primary-side feedback flyback power supply, aiming at the shortcomings of the existing dynamic control algorithm under low-power DCM, especially in the case of heavy load switching to light load, the dynamic recovery time For the defect of too long, by controlling the switching off of the primary side switching tube of the converter and the switching of the secondary side synchronous rectifier tube with a fixed duty ratio, the energy of the load capacitance at the output end is extracted to the primary side, so that the output voltage drops rapidly, and at the same time it is always at a fixed The frequency of the output voltage is sampled. When the output voltage drops to the rated value, it is judged according to the load size that the system corresponds to the steady state mode after jumping out of the high dynamic mode, and then the system enters the steady state mode. The invention can shorten the output voltage within 2.5ms, and the output voltage ripple is very small when the system leaves the dynamic mode and enters the steady state mode, and significantly improves the dynamic performance of the flyback converter under high power.

Description

technical field [0001] The invention relates to an isolated switching power supply converter, in particular to a method for improving the dynamic performance of a synchronous rectification primary-side feedback flyback power supply with heavy load and light load switching, which is suitable for synchronous rectification flyback power supply in high-power operation. Background technique [0002] Switching power supplies are usually used as power supplies for various types of electrical equipment to convert unadjusted AC or DC input voltages into adjusted AC or DC output voltages. Since the switching power supply needs to adapt to different working conditions, the performance requirements for the dynamic response of the power supply are getting higher and higher. Good dynamic effects require small voltage changes and voltage recovery times. [0003] The primary side feedback (PSR) flyback converter is widely used in the field of switching power supply because of its simple st...

AI Technical Summary

Problems solved by technology

This scheme effectively reduces the overshoot voltage and response time under DCM, and improves the dynamic performance of the converter, but there are also shortcomings

When switching from full load to very light load, the recovery time is too long, it takes 53ms

[0006] In addition, in order to speed up the dynamic response, some control methods will increase the PI parameter to speed up the compensation, so as to improve the dynamic effect, but the effect of multi-mode control on improving the dynamic performance is not much improved.

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