Basic components of switching power supply
Introduction to switching power supply
This document is intended as an intensive training for Zhang Zhansong after his advanced switching power supply design. Based on the planned arrangement, after Shen Gong explained the transformer design, in this article, he briefly introduced the transformer design principles, focusing on the circuit working principle and the calculation of key components during the design process. and selection.
The working process of the switching power supply is quite easy to understand. It has three obvious characteristics:
Switching: Power electronic devices work in a switching state rather than a linear state
High frequency: Power electronic devices work at high frequency rather than low frequency close to power frequency
DC: The switching power supply outputs DC instead of AC. It can also output high-frequency AC such as electronic transformers.
Switching power supply classification:
Switching power supplies are divided into many types according to topology: buck boost, forward flyback half-bridge, full-bridge LLC, etc., but in essence, there are only two working modes of switching power supplies: forward: it transmits energy when the switch tube is turned on, and flyback: Energy is transferred when the switch is turned off.
Current mode PWM single-ended flyback power supply
The advantages of this type of flyback power supply are: simple structure, low price, and suitable for low-power power supplies.
Disadvantages of this type of flyback power supply: small power, generally below 150w, large ripple, low voltage load adjustment rate, generally greater than 5%.
The difficulty in designing this type of flyback power supply is mainly the design of the transformer, especially the transformer with wide input voltage and multiple outputs.
