First, the main circuit from the AC power grid input, DC output of the whole process, including: 1, input filter: its role is to filter the presence of grid clutter, but also impede the clutter generated by the machine feedback to the public grid. 2, rectification and filtering: the grid AC power supply is directly rectified into a smoother DC for the next conversion. 3, inverter: rectified DC into high-frequency AC, which is the core part of the high-frequency Switching power supply is the core part, the higher the frequency, volume, weight and output power ratio of the school 4, the output rectifier and filtering: according to the needs of the load, to provide a stable and reliable DC power supply.

Fourth, the auxiliary power supply to provide all the different requirements of a single circuit power supply. 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 provided to the load RL, in the entire 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, 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 portion 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: where TON is the switch on each time, T is the switch on and off the operating cycle (i.e., the switch on time TON and off time TOFF and the sum of time). As can be seen from the formula, change the switch on time and the ratio 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 ratio 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).