Detailed explanation of working principle of switching power supply

As the name implies, switching power supply uses electronic switching devices to switch through control circuits, so as to ach

Detailed explanation of working principle of switching power supply

As the name implies, switching power supply uses electronic switching devices to switch through control circuits, so as to achieve the purpose of voltage regulation and automatic stability. Compared with traditional power supply, switching power supply has lower cost and higher output power, so it has a broader market development prospect and is deeply loved by friends. How much do you know about the working principle of switching power supply? Next, I will explain to you the working principle of switching power supply.

Analysis of working principle of switching power supply

For those who love power physics, the working principle of switching power supply is actually very easy to understand. In the linear power supply, the power transistor is working, while in the linear power supply, it is the PWM switching power supply that leads to the closure or disconnection. In both closed and open states, and the voltage of the power transistor is relatively small, a large current will be generated. When the switching power supply is turned off, it is the other way around, and the voltage is large and the current is particularly small, thus controlling the switch.

Working conditions of switching power supply

Working principle of switching power supply In addition to the above-mentioned working principle of switching power supply, switching power supply has certain working conditions during operation. For example, when the switch is working, it is not in a linear state, but in a switching state under the operation of electronic appliances; In addition, DC, the switching power supply is DC, not AC; Finally, the high frequency of switching power supply, in the working state of electronic appliances, is high frequency, not close to the working low frequency state! In the working principle of switching power supply, these working conditions are certain.

Main characteristics of switching power supply

The birth of each product has its own main characteristics, even the switching power supply. So what are the main characteristics of switching power supply besides the above different working principles? First of all, from the appearance, it is light in weight and small in size. Because there is no power frequency transformer, the weight and volume of switching power supply is only about 20% to 30% of that of linear power supply. In addition, there is a very important feature. From the working principle of switching power supply, it has high efficiency and low energy consumption. The conversion efficiency of the power transistor used is very high, generally about 60% to 70%, and about 30% to 40% in the state of linear power supply.

At present, the high-frequency switching power supply with closed-loop system on the market can also be divided into two types according to the structure: active PFC power supply and passive PFC power supply. Because the power supply designed by active PFC is more expensive than that designed by passive PFC, we can simply think that the power supply designed by active PFC is a relatively high-end power supply, while the power supply designed by passive PFC is a relatively low-end power supply. Below we will mainly explain the working principle of active PFC switching power supply.

Active PFC switching power supply: Active PFC circuits usually use two power MOSFET switches. These switches are usually placed on the radiator on the primary side. For the sake of understanding, we mark each MOSFET switch with letters: S stands for source, D stands for drain and G stands for gate.

Active PFC switching power supply: PFC diode is a kind of power diode, which usually adopts packaging technology similar to power transistor. They are very similar and are also placed on the heat sink on the primary side, but the PFC diode has only two pins. The inductance in PFC circuit is the largest inductance in power supply; The primary filter capacitor is the largest electrolytic capacitor in the primary side of active PFC power supply. Active PFC control circuits are usually based on IC integrated circuits.

By introducing the working principle of switching power supply, do you know more about the working principle of switching power supply? Switching power supply is mainly divided into active power supply and passive power supply. According to different types of switching power supply, we can understand different working principles. If we master the working principle of switching power supply, it is very important for our daily application. Nowadays, switching power supply is widely used in electronic information industry, and its working principle has been introduced. I hope everyone can have more gains.

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