Basic Components of Switching Power Supplies
Switching power supply is roughly composed of four parts: main circuit, control circuit, detection circuit, and auxiliary power supply.
1. Main circuit
Impulse current limiting: Limit the impulse current on the input side at the moment the power is turned on.
Input filter: Its function is to filter out the clutter that exists in the power grid and hinder the feedback of the clutter generated by the machine back to the power grid.
Rectification and filtering: Directly rectify the AC power supply of the power grid into smoother DC power.
Inverter: Convert rectified DC power into high-frequency AC power, 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
On the one hand, samples are taken from the output terminal, compared with the set value, and then the inverter is controlled to change its pulse width or frequency to stabilize the output. On the other hand, based on the data provided by the testing circuit, various protection measures are provided to the power supply by the control circuit after identification by the protection circuit.
3. Detection circuit
Provide various parameters and instrument data that are currently running in the protection circuit.
4. Auxiliary power supply
Implement software (remote) startup for power supply, providing power supply for protection circuits and control circuits (PWM chips, etc.).
Types and application directions of switch mode power supplies
There are two types of modern switching power supplies: one is DC switching power supply; Another type is AC switching power supply. The main focus here is on DC switching power supplies, whose function is to convert low-quality primary power sources (coarse electricity) such as mains power or battery power into high-quality DC voltage (fine electricity) that meets equipment requirements.
The core of a DC switching power supply is the DC/DC converter. Therefore, the classification of DC switching power supplies depends on the classification of DC/DC converters. That is to say, the classification of DC switching power supplies is basically the same as that of DC/DC converters, and the classification of DC/DC converters is basically the classification of DC switching power supplies.
Switching power supply is a type of power supply that utilizes modern power electronics technology to control the time ratio of switching transistors to turn on and off, maintaining a stable output voltage. Switching power supply is generally composed of pulse width modulation (PWM) control IC and switching devices (MOSFET, BJT, etc.). High frequency is the direction of its development, which makes switching power supply smaller and more widely used, especially in high-tech fields, promoting the miniaturization and portability of high-tech products.
In addition, the development and application of switch mode power supplies are of great significance in energy conservation, resource conservation, and environmental protection. Especially in the field of high-tech applications, the development of switching power supplies has been promoted, with an annual growth rate of over two digits towards the direction of light, small, thin, low-noise, high reliability, and anti-interference.
Compared to linear power supplies, the cost of both switching power supplies increases with the increase of output power, but their growth rates are different. The cost of a linear power supply is actually higher than that of a switching power supply at a certain output power point. With the development and innovation of power electronics technology, switching power supply technology is constantly innovating, and this cost reversal point is increasingly moving towards the low output power end, providing a wide range of development space for switching power supplies. High frequency switching power supply is its development direction.
