Research on Modular Design and Parallel Technology of Switching Power Supply

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Summary:

The application of single-chip control technology and soft-switching technology in the design of switching power supply module has the advantages of small switching loss, high reliability, easy parallel expansion, etc. It is the basis for power expansion and system redundancy of DC switching power supply system.

In this paper, by analyzing the basic circuit structure and working principle of DC converter, the main circuit structure, working principle, waveform and main relation are given. A converter with an isolating transformer is a converter circuit formed by inserting an isolation transformer into various points of the basic converter, with the essential characteristics of the basic converter, and at the same time, an electrical device can be realized between the input power of the converter and the load. isolation. By analyzing several converters with isolation transformers, it is concluded that each converter has its own characteristics and applicable conditions. The power electronic power conversion resonance type technology processes the power switch tube in a sinusoidal form, so that the switch tube is commutated at zero current or commutated at zero voltage, which can reduce the switching loss of the switch. Through the basic principle analysis of the zero-conversion switching converter, the operation modes of each stage in a cycle are given. The power supply system can be composed of multiple power supply modules in parallel. For the parallel power supply system, it is important to ensure the current sharing of the parallel modules. The working principle and basic characteristics of the commonly used parallel current sharing method are analyzed. The RISC instruction structure and data bus structure of the produced PICl6F series MCUs are briefly analyzed.

Through the analysis of the basic circuit of the DC converter and the parallel current sharing method, a small switching power supply module and its parallel operation system prototype are designed by using PIC series single-chip microcomputer control. The prototype experiment shows that the zero-current shutdown and zero-voltage conduction of the main loop switch can be better realized by the transformer isolation half-bridge main loop resonant circuit design. The PICl6F series single-chip microcomputer is used as the control core, and the pulse frequency can be realized by software design. The modulation control working mode better solves the complicated control circuit. By detecting the output voltage of the parallel system and communicating with each power module, the current sharing and voltage regulation control of the parallel system is realized.

Average current method automatic current sharing control circuit schematic

Power module main circuit schematic

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