Technical Knowledge Classroom: The Secret of Power Supply Topology - Power Supply

For power supplies , the ATX power supply used is essentially a switching power supply that converts AC to DC . Anything involving a switching power supply must involve the concept of topology . Topology is simply the architecture of the power supply. Just like hardware such as the CPU, the topology directly affects the performance of the power supply. In the world of power supplies, topology essentially determines the quality of the power supply. Revealing the power supply topology reveals the performance secrets of the power supply.

Topology mainly affects the conversion efficiency, dynamic capability, stability and other aspects of the power supply. However, there is no fixed matching relationship between the topology structure and the power of the power supply. And the topology structure is very detailed in classification, just like a tree diagram, which is divided into forward, full bridge and half bridge. As a result, there are few products with clear power supply topology in current products, and often only the general topology structure is written. This article will expand this key technology directly related to power supply performance layer by layer and list the power supply topology in detail.

The working principle of the power supply is simply this: the mains electricity enters the power supply and is converted into high-voltage direct current through rectification and filtering, and then converted into high-frequency low-voltage pulses through the switching circuit and high-frequency switching transformer, and then rectified and filtered to finally output low-voltage direct current. It seems very simple, but it involves a lot of details. The advancement of the topology is ultimately to provide the most stable final output.

When the mains electricity enters the power supply , it first passes through the choke coil and capacitor to filter out high-frequency clutter and in-phase interference signals. Then it passes through the inductor coil and capacitor to further filter out high-frequency clutter. After being rectified by the rectifier circuit and filtered by the large-capacity filter capacitor, the current is converted from high-voltage AC to high-voltage DC.

Although the high-voltage rectification part has gone through the process of AC---DC, this is only a preliminary process. The current cannot be directly supplied to the computer and further adjustments are required. After the AC-DC conversion, the current enters the core part of the entire power supply--the switching circuit. The switching circuit is mainly composed of two switching tubes. By turning them on and off in turn, the DC power is converted into high-frequency pulsating DC power. Next, it is sent to the high-frequency switching transformer for voltage reduction. The pulsating voltage after the high-frequency switching transformer is also rectified and filtered using diodes and filter capacitors. In addition, there will be 1 or 2 inductors and filter capacitors to filter out the high-frequency AC components.

Switching tube part

To put it more simply, a power supply is a device that is high voltage rectifier-transformer-low voltage rectifier-output. What we call topology is the components used in the power supply and the connection method of various circuits. Different topologies, in simple terms, use different components and different connection methods.

Power supply topology diagram

The components of a power supply are nothing more than inductors, resistors, capacitors and transformers, but the number, type and connection of the components result in different topological structures , which directly affect the output level of the power supply.