Switching power supply working principle: in the linear power supply, let the power transistor work in the linear mode, and linear power supply is different, PWM switching power supply is to let the power transistor work in the state of on and off, in these two states, added to the power transistor on the volt-ampere product is very small (in the on-time, the voltage is low, the current is large; off-time, the voltage is high, the current is The volt-ampere product on the power device is the loss incurred on the power semiconductor device.
Compared to a linear power supply, a PWM switching power supply operates more efficiently by "chopping" the input DC voltage into pulses of amplitude equal to the amplitude of the input voltage. The duty cycle of the pulse is adjusted by the controller of the switching power supply. Once the input voltage is chopped into an AC square wave, its amplitude can be raised or lowered by the transformer. The output voltage can be increased by increasing the number of secondary windings in the transformer. Finally these AC waveforms are rectified and filtered to obtain a DC output voltage.
The main purpose of the controller is to keep the output voltage stable, and its working process is very similar to that of a linear form of controller. This means that the controller's function blocks, voltage reference and error amplifier, can be designed to be the same as a linear regulator. Where they differ is that the output of the error amplifier (the error voltage) passes through a voltage/pulse width conversion unit before driving the power tubes.
Main applications:
Switching power supply products are widely used in industrial automation control, military equipment, scientific research equipment, LED lighting, industrial control equipment, communications equipment, power equipment, instrumentation, medical equipment, semiconductor refrigeration and heating, air purifiers, electronic refrigerators, LCD monitors, LED lamps and lanterns, communications equipment, audio-visual products, security monitoring, LED light strips The company's products are widely used in the fields of computer chassis, digital products and instruments.
Reference: Baidu Encyclopedia - Switching Power Supply