基于3525驱动板的推挽式非隔离型变压器DC-DC升压设计

Design of Push-pull Non Isolation Transformer DC-DC Boosting Based on 3525 Driver Board

设计了一种非隔离型推挽式变压器DC-DC升压方式,给出了推挽式升压主要电路模块参数的设计方法,其中包括尖峰吸收电路、MOS管外围电路、变压器以及整流桥。通过3525驱动板实现变压器输出电压非隔离反馈调节与MOS管驱动。通过设计发现在推挽式升压中:RC尖峰吸收电路,RC参数值与电路寄生电容电感、MOS管结电容以及电路整体谐振有关,并当电阻值固定时,电容越大尖峰吸收效果越好;MOS管需用NPN型,并考虑输入信号的阻抗平衡以及NMOS的安全与性能;变压器设计中需注意磁通不平衡和磁饱和引起的变压器短路,磁通不平衡可通过调节MOS管驱动信号使MOS管导通时间基本一致实现,磁饱和可通过对磁心开气隙使磁心磁饱和强度增加的方式进行调节;整流桥设计要点是考虑能量转化效率以及器件耐电压耐电流的值。通过3525驱动板的1、2以及9引脚和电阻电容实现非隔离电压采集,成本更低,并设计简单,稳定性强。

A non-isolated push-pull transformer DC-DC boosting method is designed,and the design method of the parameters of the main circuit module of the push-pull boosting is given,which includes the spike absorption circuit,the MOS tube peripheral circuit,the transformer and the rectifier bridge.Through the 3525 driver board to realize the transformer output voltage non-isolated feedback regulation and MOS tube drive.Through the design found in the push-pull boost:RC spike absorption circuit,RC parameter values and circuit parasitic capacitance inductance,MOS junction capacitance and circuit resonance,and when the resistance value is fixed,the larger the capacitance the better the spike absorption effect;MOS tubes need to be used in the NPN-type,and to consider the balance of the impedance of the input signal as well as the safety and performance of the NMOS;the transformer design needs to be aware of flux imbalance and magnetic saturation caused by transformer short-circuit.Transformer design should pay attention to the flux imbalance and magnetic saturation caused by the transformer short circuit,flux imbalance can be achieved by adjusting the MOS tube drive signal so that the MOS tube conduction time is basically the same,magnetic saturation can be adjusted through the core open air gap to increase the magnetic saturation intensity of the magnetic core;rectifier bridge design is to consider the energy conversion efficiency as well as the device resistance to the value of the voltage and current.Through the 3525 driver board 1,2 and 9 pins and resistor-capacitor non-isolated voltage acquisition,lower cost,and simple design,strong stability.