Schematic diagram of step-down chopper switching regulated power supply

The chopper-type switching regulated power supply is a DC power supply. It obtains a unidirectional square wave through the switching circuit, and then filters it to obtain a stable DC that is different from the input voltage. The so-called buck type means that no matter whether the input voltage Ui is positive or negative, the output voltage Uo is always lower than the input voltage Ui, that is, |Uo|≤|Ui|. The figure is a schematic diagram of a step-down chopper switching regulated power supply. When the switching element VT is controlled to be saturated and turned on, the electric energy is stored in the inductor L and the capacitor C and is also fed to the load. When the switching element VT is controlled to be in the off state, the energy stored in the inductor and capacitor continues to be supplied to the load, and the diode VD forms a current loop. Because the switching element VT and the load resistor RL are connected in series, it is also called a series switching regulated power supply. Assume that the on-time of the adjustment switch is ton, the load-dead time is toff, and the adjustment switch and the choke inductor are ideal components. If the adjustment switch element VT is always on and the cut-off time is zero, then Uo=Ui; if VT is always on Cut off, the conduction time is zero, then Uo=0V. With the different ratios of ton and toff, the output voltage Uo is various values ​​between O and Ui.