Constant current control system for output current of primary-side feedback flyback power supply converter

Abstract

The invention discloses a constant current control system for the output current of a primary-side feedback flyback power supply converter. Based on the conventional constant current control strategy, Ts compensation, Tr compensation, and primary-side peak current compensation are added, constant current processing of digital PI compensation is also combined, and two modes of PWM and PFM are employed for control. Without considering some compensation, under the PWM mode, the switch-on time is reduced with the reduction of a load, and the deviation of the output current from the rated current is larger and larger with the reduction of the load; under the PFM mode, the switch-on time is maintained unchanged, and the deviation of the output current from the rated current is maintained unchanged. According to the system, the constant current precision can finally reach +/-2%, and the constant current characteristic of the flyback converter is improved.

Description

technical field [0001] The invention relates to an isolated switching power converter, in particular to a constant current control system for the output current of a primary-side feedback flyback power converter. Background technique [0002] With the rapid development of household electronic equipment, the demand for high-efficiency power supplies is also increasing, which leads to the rapid development of AC-DC power converters. The development of electronic equipment has put forward new indicators for AC-DC power converters, and the energy consumption and control accuracy of equipment have become the focus of the current power supply industry. In the field of power supply design, the flyback topology is widely used in low-power converters due to its simple structure, low cost, and wide input range. Such as offline charger, LED driver, etc. With the development of miniaturization and low-cost requirements of products, the primary side feedback method is proposed. Howeve...

AI Technical Summary

Problems solved by technology

[0006] Aiming at the defect of poor constant current accuracy of the existing primary-side feedback flyback power supply, the present invention provides a constant-current control system for the output current of the primary-side feedback flyback power converter, by analyzing three factors that affect the current accuracy , and then get the impact of various factors on the current accuracy, and on this basis to compensate for each factor, through the final simulation and test, comparison found that the effect of the constant current accuracy of ± 2% can be obtained, thereby improving the flyback conversion The constant current characteristic of the device further expands the application of the primary side feedback flyback switching power supply in the field requiring accurate constant current

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