How does a switching regulated power supply work?
A switching regulated power supply is a type of power supply that works by using switching tubes to control the magnitude of the power supply output voltage in order to stabilize the output. Its working principle can be divided into the following aspects:
First, the classification of switching regulated power supply
Before understanding the working principle of switching regulated power supply, we need to understand the classification of switching regulated power supply. According to different working methods, switching regulated power supply can be divided into AC-DC switching power supply and DC-DC switching power supply.
AC-DC switching power supply: the input voltage is alternating current (AC), which is converted to stable DC output after rectification, filtering, switching control and other processes in the input circuit.
DC-DC switching power supply: the input voltage is direct current, after switching conversion, filtering and other processes in the input circuit, and then output a stable direct current to supply the load.
Second, the working principle of switching tube
In the switching regulated power supply, the application of switching tubes is indispensable. Switching tube usually refers to transistors, power field effect tubes, insulated gate bipolar transistors and other semiconductor components. It is characterized by low static power consumption, high switching speed and high controllability.
When we want to control the voltage, we first need to make the power supply output voltage higher or equal to the desired voltage, which will turn the switching tube on, and the current goes through the switching tube into the inductor. When the current passes through the inductor, a magnetic field is formed and an electric potential is generated on the wires around the inductor. This electromotive force creates a so-called loop oscillation in the capacitor, producing a periodic resonant voltage. When the switching tube cuts off, the current in the inductor is suddenly interrupted, and the magnetic energy stored in the inductor drives the current to continue to flow and pass through the output to be consumed by the load, which outputs a fixed voltage. This is repeated to create a stable and controllable output voltage.
Third, the realization of switching regulator circuit
As we know, the switching speed of the switching tube is very fast, can realize high frequency switching, has the advantages of energy saving, stability, high efficiency and so on. In the switching regulated power supply, first of all, we need to design a switching regulator circuit to realize the control of the switching tube. Then the output voltage is stabilized by filtering, loop feedback and so on.
In the switching regulated power supply, the commonly used switching regulator circuits are diode regulator circuit, inductor regulator circuit, magnetic element regulator circuit and so on, of which the most common is the inductor regulator circuit.
The inductive voltage regulator circuit is mainly composed of switching tubes, inductors, capacitors, diodes and output circuits. Its working principle is the same as above, when the switching tube is on, the output voltage can be regulated by the inductor, and then supplied to the load through the output circuit. And in the switching tube cut-off, the energy in the inductor can be converted to output voltage through the diode, and regulated.
Small and medium power switching regulated power supply can be realized directly with the transistor drive circuit, while the larger power switching regulated power supply requires the use of control chips or analog control circuits to achieve precise control.
Fourth, the loop feedback control
As the output voltage of the power supply changes with the temperature, load and input voltage changes, the output voltage needs to be regulated control. In the switching regulated power supply, loop feedback control is often used to stabilize the output voltage by monitoring the output voltage and providing feedback and regulation to stabilize the output voltage.
Specifically, the loop feedback control realizes the regulation of the output voltage by comparing the difference between the output voltage and the set voltage, and carrying out arithmetic, amplification, filtering, and then controlling the conduction and cutoff of the switching tube. In this process, the stability of the system should be ensured, that is, the regulation speed is fast enough, but not too fast, otherwise it will cause system instability.
In short, the switching regulated power supply is a widely used type of power supply, and its working principle is to use the switching tube to control the voltage, and at the same time through the filtering, loop feedback and other ways of regulating and controlling the voltage, in order to achieve a stable and controllable output voltage. With the continuous progress of technology, switching regulated power supply has become an indispensable part of many electronic devices, greatly promoting the development and innovation of the electronics industry.
