What is a switching power supply? Maintenance essentials of switching power supply

Nowadays, there are more and more electrical appliances in life, and their functions are becoming more and more abundant. The structure and components have also become more complicated. There are many new components that you may not be very clear about. For example, switching power supply, this kind of widely used device, is it that some friends don’t know it very well? Then let’s take a look at what is a switching power supply and what are the maintenance methods of a switching power supply.
What is a switching power supply
1. A switching power supply is a power supply that uses modern power electronics technology to control the time ratio of the switching tube on and off to maintain a stable output voltage. Switching power supply It is generally composed of pulse width modulation control IC and MOSFET. Compared with the linear power supply, the cost of the switching power supply increases with the increase of the output power, but the growth rate of the two is different.
2. The ordinary power supply is generally a linear power supply. The linear power supply refers to the power supply in which the regulating tube works in a linear state. The switching power supply is a relatively new type of power supply. It has the advantages of high working efficiency, light weight, can increase and decrease voltage, and large output power. The high frequency of switching power supply is the direction of its development. High frequency makes switching power supply miniaturized and makes switching power supply enter a wider application field. In addition, the development and application of switching power supply are of great significance in saving energy, saving resources and protecting the environment.
3. The switching power supply is to use electronic switching devices (such as transistors, field effect transistors, thyristors, etc.), through the control circuit, to make the electronic switching devices “turn on” and “off” continuously, Let the electronic switching device perform pulse modulation on the input voltage, so as to realize DC/AC, DC/DC voltage conversion, and the output voltage can be adjusted and automatically stabilized.
4. Switching power supplies generally have three working modes: fixed frequency and pulse width mode, fixed frequency and variable pulse width mode, and variable frequency and pulse width mode. It is roughly composed of four parts: main circuit, switching power supply control circuit, detection circuit and auxiliary power supply.
Switching power supply maintenance essentials
1. When repairing a switching power supply, first use a multimeter to check whether each power component is broken down and short-circuited, such as a power rectifier bridge stack, a switch tube, a high-frequency high-power rectifier Tube; Whether the high-power resistor that suppresses the inrush current is blown. Then check whether the resistance of each output voltage port is abnormal. If the above parts are damaged, they need to be replaced.
2. After the power is turned on, it still cannot work normally. Next, check the power factor module (PFC) and pulse width modulation module (PWM), check relevant information, and be familiar with the function of each pin of the PFC and PWM module and whether the module is normal. A prerequisite for work. For a power supply with a PFC circuit, it is necessary to measure whether the voltage at both ends of the filter capacitor is about 380VDC. If there is a voltage of about 380VDC, it means that the PFC module is working normally.
3. In the maintenance practice of switching power supply, many switching power supplies use UC38×× series 8-pin PWM components.due to increased flow. In this case, disconnect the external circuit connected to the VR terminal, VR changes from 0V to 5V, the PWM components work normally, and the output voltage is normal.
4. The switching power supply circuit is easy or difficult, the power is large or small, and the output voltage is various. As long as you grasp the core of it and fully familiarize yourself with the basic structure and module characteristics of switching power supply, you can quickly eliminate the fault of switching power supply.
Switching power supply is very important for many household appliances, and it is often a link that is prone to problems. As ordinary consumers, you may not be familiar with switching power supplies, so that when electrical appliances fail, sometimes you don’t know where the problem lies. The introduction of what is a switching power supply and the maintenance essentials of a switching power supply have been read above. It will be helpful for everyone to understand the role of a switching power supply for home appliances.