Basic Principle And Structure Of Switching Power Supply

- Dec 28, 2019-

Power supply (PSU) is actually short for PowerSupplyUnit. The often mentioned PC power supply is actually an abbreviation. If strictly speaking, the PC power supply should be called a switching power supply applied to the PC host. Of course, such a name is too cumbersome, so in In the following paragraphs, the shortest term power will be used.


For the computer, the power supply is an important part. It is the heart of the computer. It continuously provides stable and stable power support for the CPU, graphics card, hard disk, and other hardware parts, which guarantees that we can use the computer normally. All kinds of work. So if the power supply does not work or is damaged, other hardware in the computer will also be affected, and it is likely to cause more serious losses.


Therefore, in general, you should first buy a good genuine power supply, and then choose other hardware configurations. But most people do the opposite, often choosing other hardware first, and then using the last few money to buy power.


And if you are in the situation just described, then we still sincerely recommend that you browse through this article first, because it will be very helpful in your choice of power products, and may also change your attitude towards power Let you know how important the power supply is in your computer.


All current power supplies used in computers can be referred to as switching power converters, or SPC for short. The principle of switching power supply is actually relatively simple. It divides the energy obtained from the national power grid into small high-frequency energy packets, and then transfers them through electrical components such as capacitors and inductors to the end. The small energy packets are fused together, so that the corrected energy can be smoothly output. Therefore, compared with other power supply forms, switching power supplies are smaller and more efficient.


Compared with LinearPowerSupply, switching power supplies have two main advantages. Switching power supplies have a completely different design from linear power supplies, so the size and weight of the power supply are greatly reduced, and the conversion efficiency of the power supply can be easily Over 90%.


However, on the other hand, switching power supplies also have the most obvious drawback. Due to the complexity of the switching power supply itself, a large amount of electromagnetic radiation is generated. Therefore, current switching power supplies are equipped with EMI filters or RFI shielding.


● EMI transient filter (EMI / TransientFilter): Suppresses the EMI / RFI when the current enters and inputs, and plays the role of protecting the voltage surge peak.


● BridgeRectifier: Corrects the input AC AC power to DC DC power.


● Active PFC (APFC): Controls the current of the input power supply so that the current waveform becomes a proportional power supply voltage waveform. (Make voltage and current have a linear proportional relationship)


● Main Switches: Cuts the DC signal into a small high-frequency energy packet.


● Transformer: It is independent between the primary side and the secondary side, and reduces the high voltage to low voltage.


● Secondary filter rectification (OutputRectifiers & Filters): filter rectification of the step-down DC power.


● Protection Circuits (ProtectionCircuits): When there is a serious problem with the power supply, turn off the power in time.


● PWM controller (PWMController): Periodically adjust the main switch to maintain stable output voltage under all loads.


● Isolator: Blocks voltage feedback from DC output and to PWM control.


The part before the power circuit transformer is usually called the primary side, and the part behind the transformer is called the secondary side. Simply put, the primary side is mainly responsible for the high-voltage part, and the secondary side is mainly responsible for the low-voltage part.