dc—dc变换器（DC - DC converter）.docVIP

dc—dc变换器（DC - DC converter） The design of DC-DC boost power converter A design task: the design of a 12V will rise to DC-DC 24V converter. Under resistive load requirements are as follows: 1, the output voltage of U0=24V. 2, the maximum output current of I0max=1A. 3, when the input UI=11~13V changes, voltage adjustment rate is less than 2% SV (in I0=1A). 4, when the I0 changes from 0 to 1A, load adjustment rate is less than 5% SI (in UI=12V). 5, the converter in full load efficiency is more than 70%. 6, the output noise ripple voltage peak - U0PP = 1V (UI=12V, U0=24V, I0=1A). 7, the converter has the function of overcurrent protection, current I0 (th) is set in 1.2A. Two, design analysis 1, the working principle of DC-DC converter Many kinds of DC-DC power converter. According to the input / output circuit is isolated to points, can be divided into non isolated and isolated two categories. Non isolated DC-DC converter and can be divided into the buck, boost, polarity reversal type and other types of DC-DC converter; isolation type can be divided into several single ended forward, flyback, double end double half bridge, full bridge etc.. The following work mainly discusses the principle of non isolated step-up DC-DC converter. Figure 1 (a) is the main circuit of DC-DC boost converter, which is mainly composed of a power switch tube VT, inductor L, a capacitor C and freewheeling diode VD. The working principle of the circuit, when the control signal Vi is high, the switch VT is switched on, the energy flows from the input power stored in the inductor L, because the VT is switched on when the saturated pressure drop is very small, so the diode reverse bias and stop at D, the energy stored in the capacitor in the C release to load. When the control signal Vi is low, the switch VT is closed, because the current cannot inductor L mutation induced electromotive force produced by it will prevent the decrease of current, polarity of EMF is left negative right, the diode D is