DC- dc converter
直流变换器原理-英文
DC-DC Converter Basics
ABSTRACT A DC-to-DC converter is a device that accepts a DC input voltage and produces a DC output voltage. Typically the output produced is at a different voltage level than the input. In addition, DC-to-DC converters are used to provide noise isolation, power bus regulation, etc. This is a summary of some of the popular DC-to-DC converter topolopgies:
1. BUCK CONVERTER STEP-DOWN CONVERTER
In this circuit the transistor turning ON will put voltage Vin on one end of the inductor. This voltage will tend to cause the inductor current to rise. When the transistor is OFF, the current will continue flowing through the inductor but now flowing through the diode. We initially assume that the current through the inductor does not reach zero, thus the voltage at Vx will now be only the voltage across the conducting diode during the full OFF time. The average voltage at Vx will depend on the average ON time of the transistor provided the inductor current is continuous.
Fig. 1: Buck Converter
Fig. 2: Voltage and current changes To analyse the voltages of this circuit let us consider the changes in the inductor
current over one cycle. From the relation
the change of current satisfies
