Method for improving dynamic performance of synchronous rectification primary side feedback flyback power supply

Abstract

The invention discloses a method for improving dynamic performance of a synchronous rectification primary side feedback flyback power supply. Specific to deficiencies of an existing dynamic control algorithm under the low-power DCM condition, especially the defect that dynamic recovery time is too long when a heavy load is switched into a light load, turn-off of a switching tube at a primary sideof a converter as well as a synchronous rectifier tube at a secondary side are controlled to fix a duty cycle switch, and energy of a load capacitor at an output terminal is extracted to the primary side, so that an output voltage drops rapidly; meanwhile, the output voltage is always sampled at a fixed frequency, when the output voltage drops to a rated value, a corresponding steady-state mode ofa system at the moment after the system jumps out of a high dynamic mode is judged according to the size of a load, and then the system enters the steady-state mode. The method disclosed by the invention can shorten the output voltage to be within 2.5ms, and output voltage ripple is small when the system leaves the dynamic mode and enters the steady-state mode, so that dynamic performance of a flyback converter at high power is obviously improved.

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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