Different names for switching power supply

Everyone calls it switching power supply instead of power switch. Why? We often talk about switching power supply and power switch. What is their mechanism and how they work? Let’s take a look at the similarities and differences:

Definition of switching power supply

A switching power supply is a power supply that uses modern power electronics technology to control the turn-on and turn-off time ratio of the switching tube to maintain a stable output voltage. The switching power supply is generally composed of a pulse width modulation (PWM) control IC and a MOSFET. With the development and innovation of power electronics technology, switching power supply technology is also constantly innovating. At present, switching power supply is widely used in almost all electronic equipment due to its small size, light weight and high efficiency. It is an indispensable power supply method for the rapid development of today's electronic information industry.

Switching power supply is relative to linear power supply. Its input terminal directly rectifies alternating current into direct current, and then uses a switch tube to control the on and off of the current under the action of a high-frequency oscillation circuit to form a high-frequency pulse current. With the help of an inductor (high-frequency transformer), a stable low-voltage direct current is output. Since the size of the transformer's magnetic core is inversely proportional to the square of its operating frequency, the higher the frequency, the smaller the core. This can greatly reduce the size of the transformer and reduce the weight and size of the power supply.

And because it controls DC directly, this power supply is much more efficient than a linear power supply. This saves energy, so it is favored by people. But it also has disadvantages, that is, the circuit is complex, maintenance is difficult, and the circuit is seriously polluted. The power supply is noisy and is not suitable for use in some low-noise circuits.

Characteristics of switching power supply

With the development and innovation of power electronics technology, switching power supplies are currently widely used in almost all electronic equipment due to their small size, lightweight and high efficiency. Its importance is evident.

Classification of switching power supplies

According to the way switching devices are connected in the circuit, switching power supplies can be generally divided into three categories: series switching power supplies, parallel switching power supplies, and transformer switching power supplies. Among them, transformer-type switching power supply can be further divided into: push-pull type, half-bridge type, full-bridge type, etc. According to the excitation of the transformer and the phase of the output voltage, it can be divided into: forward type, flyback type, single exciting type and double exciting type.

The difference between the two power supplies

Ordinary power supplies are generally linear power supplies. Linear power supplies refer to power supplies where the regulator tube works in a linear state. But in switching power supply, it is different. The switching tube (in switching power supply, we generally call the adjusting tube switching tube) works in two states: on and off: on - the resistance is very small; off - the resistance is very small. big. Switching power supply is a relatively new type of power supply. It has the advantages of high efficiency, light weight, ability to increase and decrease voltage, and high output power. However, since the circuit works in a switching state, the noise is relatively large.

Summary: Ordinary power supplies and switching power supplies have the same voltage adjustment tube, which uses the feedback principle to regulate voltage. The difference is that switching power supplies use switching tubes for adjustment, while ordinary power supplies generally use the linear amplification area of ​​triodes for adjustment. In comparison, the switching power supply has low energy consumption, a wide applicable range for AC voltage, and a better ripple coefficient of output DC. The disadvantage is switching pulse interference.

different ways of working

1 linear power supply

The power adjustment tube of the linear power supply always works in the amplification area, and the current flowing through it is continuous. Since the adjustment tube consumes a large amount of power, it requires a larger power adjustment tube and is equipped with a large radiator, causing serious heating and low efficiency. Generally between 40% and 60%, it can be said to be a very good linear power supply. The working mode of linear power supply requires a voltage converter device to change from high voltage to low voltage. Generally, it is a transformer, but there are also others like KX power supply, which then rectifies and outputs DC voltage. As a result, it is very large, bulky, inefficient, and generates a lot of heat. It also has advantages: small ripple, good adjustment rate, and small external interference. Suitable for use with analog circuits, various amplifiers, etc.

2 switching power supply

Its power device works in a switching state, and energy is temporarily stored through the inductor during voltage adjustment. In this way, its loss is small, its efficiency is high, and its requirements for heat dissipation are low, but it also has a negative impact on the transformer and energy storage inductor. For higher requirements, materials with low loss and high magnetic permeability should be used. Its transformer is as small as a word. The total efficiency is 80% to 98%. The switching power supply has high efficiency but small size. However, compared with the linear power supply, its ripple and voltage and current regulation rate are at a certain discount. This is an analysis of some knowledge points about switching power supplies. I hope I can help you.