Detailed Explanation of the Definition and Working Principle of Switching Power Supplies
The power supply used by personal PCs is based on a technology called "switching mode", so we often refer to personal PC power supplies as Switching Mode Power Supplies (SMPS), also known as DC-DC converters. In this article, we will explain the working mode and principle of switch mode power supplies, introduce the internal components of switch mode power supplies, and the functions of these components.
What do you know about linear power supplies
At present, there are mainly two types of power supplies: linear power supplies and switching power supplies. The working principle of a linear power supply is to first convert 127 V or 220 V mains electricity into low voltage electricity, such as 12V, through a transformer, and the converted low voltage is still AC power; Then, a series of diodes are used for correction and rectification, and the low-voltage AC power is converted into pulsating voltage (as indicated by "3" in Figures 1 and 2); The next step is to filter the pulsating voltage through a capacitor, and then convert the filtered low-voltage AC power into DC DC power (as indicated by "4" in Figures 1 and 2); At this point, the low-voltage direct current obtained is still not pure enough and may have certain fluctuations (this voltage fluctuation is commonly referred to as ripple), so it is necessary to use a voltage regulator diode or voltage rectifier circuit for correction. Finally, we can obtain pure low-voltage DC output.
Although linear power supplies are highly suitable for powering low-power devices such as cordless phones, gaming consoles like PlayStation/Wii/Xbox, etc., they may not be sufficient for high-power devices.
For a linear power supply, the size of its internal capacitance and transformer is inversely proportional to the frequency of the AC mains: that is to say, if the frequency of the input mains is lower, the linear power supply requires larger capacitance and transformer, and vice versa. Due to the current use of AC mains power with a frequency of 60Hz (some countries use 50Hz), which is a relatively low frequency, the size of its transformers and capacitors is often relatively large. In addition, the larger the surge of AC mains power, the larger the size of the transformer of the linear power supply.
From this, it can be seen that for the personal PC field, manufacturing a linear power supply will be a crazy move because its volume will be very large and its weight will also be very heavy. So individual PC users are not suitable for using linear power supplies.
