Constant voltage control method for output voltage of primary-side feedback flyback type converter

Abstract

The invention relates to a constant voltage control method for output voltage of a primary-side feedback flyback type converter. On the basis of a main topological structure of the flyback type converter, the output voltage is accurately sampled on a primary-side auxiliary winding by a DAC sampling mechanism, a pure digital mode is completely used on the condition of no adoption of a traditional large-area A/D converter and is self adaptively inserted into a DCM, a reference voltage V<REF> is obtained by the DAC sampling mechanism and a load detection module, the reference voltage V<REF> in a digital control circuit is adjusted according to accurate feedback quantity, and the accurate control of the output voltage in a continuous conduction mode is finally achieved.

Description

technical field [0001] The invention belongs to the technical field of isolated switching power supply converters, in particular to an output voltage constant voltage control method of a primary-side feedback flyback 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 control accuracy of equipment has become the focus of the current power supply industry. In the field of power supply design, the flyback topology is widely used in medium and small power converters due to its simple structure, low cost, and wide input range. Such as car converters, electric vehicle battery chargers, notebook power adapters, etc. With the development of products towards low cost and miniaturization requirement...

AI Technical Summary

Problems solved by technology

[0005] However, in actual situations, the encoding circuit required by the analog-to-digital converter is very complicated, which leads to an increase in the chip area and cost of the controller, and loses the low-cost advantage of the flyback converter

Secondly, ADC corner point sampling is inflexible, and the analog compensation method has poor adaptability, which cannot achieve the best stability and fast dynamic response under different loads.

At present, the continuous conduction mode sampling scheme is not yet mature, and the DCM insertion strategy of fixed insertion mode is generally adopted, which usually causes problems with large ripples, such as figure 2 shown

In addition, the analog-to-digital converter is an analog structure, and the aging of components and the influence of temperature on the parameters of components are inevitable, making analog signals susceptible to interference during transmission

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