中文说明：
斩波电路也称为直接直流变流电路，它的功能设计将直流电变为另一固定电压或可调 电压的直流电，下面给出一种降压斩波电路。
English Description：
Chopper circuit is also known as direct DC converter circuit, its function design will change DC into another fixed voltage or adjustable voltage DC, the following gives a buck chopper circuit.