I. Schematic diagram of switching power supply-what is switching power supply?
1. switching power supply is a kind of power supply which uses modern power electronics technology to control the switching time ratio and keep the output voltage stable. Switching power supply usually consists of pulse width modulation control IC and MOSFET. Compared with linear power supply, the cost of the two switching power supplies increases with the increase of output power, but the growth rate will be different.
2. Ordinary power supply is generally linear power supply. Linear power supply refers to the power supply in which the regulating tube is in a linear state. Switching power supply is a relatively new type of power supply. It has the advantages of high efficiency, light weight, step-up and step-down, high output power, etc. High frequency switching power supply is its development direction. High frequency makes switching power supply miniaturized, and switching power supply has entered a wider application. In addition, the development and application of switching power supply is of great significance to energy saving, resource saving and environmental protection.
3. Switching power supply adopts electronic switching devices (such as transistors, field effect transistors, thyristors, etc.). Through the control circuit, the electronic switching device is continuously "on" and "off", so that the electronic switching device modulates the input voltage to realize DC/ AC and DC/DC voltage conversion, and the output voltage can be adjusted automatically.
4. Switching power supply generally has three working modes: frequency, fixed pulse width mode, fixed frequency, variable pulse width mode, variable frequency and pulse width mode. It consists of main circuit, switching power supply control circuit, detection circuit and auxiliary power supply.
Second, the schematic diagram of switching power supply-the working principle of switching power supply
Switching power supply can make the power transistor work in the on and off state. Actually, the input DC voltage amplitude is converted into a pulse voltage equal to the input voltage amplitude. Its working principle is that the volt-ampere product applied to the power transistor is very small (in the on state, the voltage is low and the current is large; In the off state, the voltage is high and the current is small), that is, the loss produced by the power transistor is very small.
Three. Schematic diagram of switching power supply-working conditions of switching power supply
In addition to the above-mentioned working principle of switching power supply, while the working principle of switching power supply is running, the switching power supply is also in a certain working state, such as switching. It is not a linear country when working, but in the work of electronic equipment. Take DC as an example, the switching power supply is DC, not AC; The high frequency of the latter switching power supply is the high frequency in the working state of electronic equipment, which is not close to the working low frequency state. In the working principle of switching power supply, these working conditions are affirmative.
Four. Schematic diagram of switching power supply-composition of switching power supply
1. main circuit
Surge current limit: limit the surge current at the input side of the power supply.
Input filter: used to filter the clutter in the grid and prevent the clutter generated by the machine from being fed back to the grid.
Rectification and filtering: directly rectify the alternating current of the power grid into smoother direct current. Inverter: the rectified DC power supply becomes high-frequency alternating current, which is the core part of high-frequency switching power supply.
Output rectification and filtering: provide stable and reliable DC power supply according to load requirements.
2. Control circuit
Sampling from the output, comparing with the set value, and then controlling the inverter to change its pulse width or pulse frequency to make the output stable; According to the data provided by the test circuit, the protection circuit is identified and the control circuit is provided for various power supplies. Promise.
3. Detection circuit
Provide various parameters and various instrument data for the protection loop operation.
4. Self-provided power supply equipment
Realize power software (remote) startup, protection circuit and control circuit.
The above is the introduction of the schematic diagram of switching power supply that we brought to you.