The third type is buck -boost Chopp

第三种是降压-升压斩波器，其原理图如图2-3所示。让电路中的电感L和电容C无限大。这样，流过电感器的电流为固定值，并且c两端的电压，即r两端的电压，保持U0不变。<br>当v接通时，e给l充电，流过l的电流记为。同时，电容器c还充当电源，保持U0不变并向R释放能量。此后，当v关闭时，在l释放给r之前获得的能量，并写入流过l的电流作为。此时，R两端的电压极性为负和正，而E极性恰好相反。因此，该电路也称为反极性斩波电路。

第三种类型是降压增压斩波器，其示意图显示在图 2-3 中。让电路中的电感 L 和电容 C 无限。这样，流经电感器的电流是一个固定值，c 的两端的电压（即 r 两端的电压）保持不变。<br>当v打开时，e收费l，流经l的电流被写成。同时，电容器 c 也充当电源，保持 U0 不变，向 R.释放能量。此后，当v被关闭时，在我被释放到r之前获得的能量，流经l的电流被写成。此时，R 两端电压的极性为负值和正极，而 E 的极性正好相反。因此，此电路也称为反向极性切碎器电路。

The third type is buck -boost Chopper, and its schematic diagram is shown in Figure 2-3. Let the inductance L and capacitance C in the circuit be infinite. In this way, the current flowing through the inductor is a fixed value, and the voltage at both ends of c, that is, the voltage at both ends of r, keeps U0 unchanged.When v is on, e charges l, and the current flowing through l is written as. At the same time, capacitor c also acts as a power supply, keeping U0 unchanged and releasing energy to R .. Thereafter, when v is turned off, the energy obtained before l is released to r, and the current flowing through l is written as. At this time, the polarity of the voltage at both ends of R is negative and positive, while the polarity of E is just the opposite. Therefore, this circuit is also called Reverse polarity chopper circuit.<br>