High frequency switching power supply principle
High-frequency switching power supply (also known as switching rectifier SMR) achieves high efficiency and miniaturisation through the high-frequency operation of MOSFETs or IGBTs, with the switching frequency generally controlled in the range of 50-100kHz. In recent years, the power capacity of the switching rectifier has been expanding, the single capacity has been expanded from 48V/12.5A, 48V/20A to 48V/200A, 48V/400A. high-frequency switching power supply is an upgraded alternative to the traditional rectifiers (silicon rectifiers, silicon controlled rectifiers). High-frequency switching power supply with easy to use, small size, high efficiency, stable work, plating layer detailed and other absolute advantages to quickly occupy the market. Widely used in electroplating, electrolysis, oxidation and other surface treatment industry.
Principle of high frequency switching power supply
Main circuit
Input from the AC power grid, DC output of the whole process, including: 1, input filter: its role is to filter the presence of grid clutter, but also impede the machine generated by the clutter feedback to the public grid. 2, rectification and filtering: the grid AC directly rectified into a smoother DC for the next level of transformation. 3, inverter: rectified DC into high-frequency alternating current, this is the core part of the high-frequency, the higher the frequency, the higher the volume, weight and output of the power supply. The higher the frequency, the smaller the ratio of volume, weight and output power.4. Output rectification and filtering: according to the needs of the load, provide a stable and reliable DC power supply.
Control circuit
On the one hand, take samples from the output, compare it with the set standard, and then control the inverter, change its frequency or pulse width to achieve stable output, on the other hand, according to the information provided by the test circuit, identified by the protection circuit, and provide the control circuit to carry out a variety of protective measures for the whole machine.
Test Circuit
In addition to providing various parameters in the protection circuit in operation, it also provides various display instrument information.
Auxiliary power supply
Provides power supply for different requirements of all single circuits. Switching control voltage regulator principle switch K to a certain time interval repeatedly on and off, in the switch K on, the input power supply E through the switch K and filtering circuit to provide the load RL, in the whole switch on period, the power supply E to the load to provide energy; when the switch K off, the input power supply E will interrupt the provision of energy. It can be seen that the input power supply to the load to provide energy is intermittent, in order to enable the load to get continuous energy supply, switching regulated power supply must have a set of energy storage device, a part of the energy will be stored when the switch is turned on, when the switch is disconnected, to the load release. In the figure, the circuit consisting of inductor L, capacitor C2 and diode D has this function. Inductor L is used to store energy, and when the switch is disconnected, the energy stored in inductor L is released to the load through diode D, so that the load receives continuous and stable energy, because diode D makes the load current continuous, so it is called a continuity diode. The average value of the voltage between AB EAB can be expressed in the following formula: EAB = TON / T * E in which TON for each time the switch on time, T for the switch on and off the operating cycle (i.e., switch on time TON and off time TOFF and the sum). As can be seen from the formula, change the switch on time and the proportion of the operating cycle, the average value of the voltage between the AB also changed, therefore, with the load and the input power supply voltage changes automatically adjust the proportion of TON and T will be able to make the output voltage V0 to maintain the same. Changing the on-time TON and the proportion of the operating cycle is also to change the duty cycle of the pulse, this method is called "time ratio control" (TimeRatioControl, abbreviated as TRC).
