Three conditions of switching power supply
The working principle of the switching power supply The working process of the switching power supply is quite easy to understand. In the linear power supply, the power transistor is made to work in the linear mode. Unlike the linear power supply, the PWM switching power supply makes the power transistor work in the on and off state. , in these two states, the volt-ampere product added to the power transistor is very small (when it is turned on, the voltage is low and the current is large; when it is turned off, the voltage is high and the current is small) / volts on the power device The Ampere product is the loss generated on the power semiconductor device. Compared with linear power supplies,
Working principle of switching power supply
The working process of the switching power supply is quite easy to understand. In the linear power supply, the power transistor is made to work in a linear mode. Unlike the linear power supply, the pwm switching power supply makes the power transistor work in the on and off states. In the state, the volt-ampere product added to the power transistor is very small (when it is turned on, the voltage is low and the current is large; when it is turned off, the voltage is high and the current is small) / the volt-ampere product on the power device is the power semiconductor losses incurred on the device. Compared with the linear power supply, the more efficient working process of the pwm switching power supply is achieved by "chopping", that is, chopping the input DC voltage into a pulse voltage whose amplitude is equal to the input voltage amplitude. 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 stepped up or down through a transformer. By increasing the number of secondary windings of the transformer, the number of output voltage groups can be increased. 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 operation is very similar to the linear form of the controller. That is to say, the functional block, voltage reference and error amplifier of the controller can be designed to be the same as that of the linear regulator. The difference between them is that the output of the error amplifier (error voltage) passes through a voltage/pulse width conversion unit before driving the power transistor. There are two main working modes of switching power supply: forward conversion and boost conversion. Although the arrangement of their various parts is very small, the working process is very different, and each has its own advantages in specific applications.
Three conditions of switching power supply
switch
Power electronics operate in a switching state rather than a linear state
high frequency
Power electronic devices operate at high frequencies rather than low frequencies close to industrial frequencies
DC
The switching power supply outputs DC instead of AC and can also output high-frequency AC such as electronic transformers
Classification of switching power supply
In the field of switching power supply technology, people are developing related power electronic devices and switching frequency conversion technology at the same time. The two promote each other to promote switching power supply to light, small, thin, low noise, high reliability, development in the direction of anti-jamming. Switching power supplies can be divided into two categories: AC/DC and DC/DC. There are also AC/ACDC/AC such as inverters. DC/DC converters have now been modularized, and the design technology and production processes have been matured at home and abroad. Standardization has been recognized by users, but the modularization of AC/DC, due to its own characteristics, encounters more complicated technical and process manufacturing problems in the process of modularization. The structure and characteristics of the two types of switching power supplies are described below.
