There are many types of switching regulated power supplies, but the basic circuit is composed of a linear filter, a rectifier filter, a direct current/direct current (DC/DC) converter and a constant voltage control circuit.
220V/50H: The AC voltage passes through the linear filter to filter out the pulse interference in the power grid, and then enters the rectification filter circuit, and the output DC high voltage is added to the DC/DC converter for power conversion, and the DC voltage that meets the requirements is output to the load. The voltage stabilization control circuit includes sampling, comparison and amplification, reference and control adjustment circuits, etc. When the input voltage is unstable for some reason, the switching elements in the DC/DC converter can be automatically adjusted through the operation of the voltage stabilization control circuit. The off-time ratio can achieve the purpose of automatically adjusting the output voltage and keeping the output voltage stable.
A DC/DC converter is a conversion circuit that converts one DC voltage into another DC voltage. Generally, the power supply voltage required by various electronic devices is different. Using a DC/DC converter, the DC voltage output by the rectifier can be converted into the DC voltage required by the electronic device.
Compared with linear regulated power supplies, the main features of switching power supplies are:
(1) High efficiency and low power consumption. The adjustment tube of the switching power supply works in the switching state, so the power consumption of the adjustment tube is extremely small, and the efficiency is above 80%.
(2) Wide range of voltage regulation. When the AC input voltage of the linear regulated power supply is lower than 160V, the output voltage will not be stable, and the efficiency will decrease when the input AC voltage is high. The switching power supply can achieve a good voltage stabilization effect when the AC input voltage changes in the range of 130-260V.
(3) High stability and reliability. The small power consumption makes the temperature rise in the electronic equipment low, reduces the high temperature damage rate of the surrounding components, and greatly improves the thermal stability and reliability of the equipment.
(4) Small size and light weight. The switching power supply can directly rectify the AC voltage input from the power grid, and then obtain various AC voltages through a high-frequency transformer, which saves the heavy power frequency transformer and greatly reduces the weight of the power supply. In addition, due to the high operating frequency of the switching power supply, the filter capacitor and inductance can use components with smaller values, which can also reduce the volume and weight.
(5) Safe and reliable. Switching power supply can easily design automatic protection circuit. When the circuit fails or is short-circuited, it can automatically cut off the power supply to prevent the expansion of the fault range.
The main problem of switching power supply is that the circuit is more complicated, the output ripple voltage is higher, and the transient response is poor. At present, countries all over the world are vigorously researching and developing new switching power supplies to meet the needs of miniaturization and high efficiency of various electronic equipment.
