Research On Low Voltage And High Current DC-DC Converter

As the work of large scale integrated circuit is normal, VRM is required to decrease low output voltage, continuous to increase output current, and also meets high efficiency, rapid dynamic response etc, in order to meet these needs, low voltage and high current DC-DC converter reflects the development orientation of switching power supply.In this thesis, the basic theory of switching power supply is described in detail, meanwhile, the basic theory, power loss and control method of Buck converter are analyzed. As for synchronous rectification, multiphase crisscross parallel connection, current sharing techniques is researched further then a design scheme for low voltage and large current DC-DC converter is put forward. The four phase crisscross parallel Buck converter circuit is simulated by PWM modulation and four phase 90°phase difference method in Matlab/Simulink. As the output voltage is 1.5V, the peak-peak value of ripples voltage is 1×10-5V; meanwhile, by adopting"maximum current-sharing technique"four phases Buck converter can realize current equalization, each current mean value is all 37.28A; the output current mean value is 149.08A, moreover, the output current ripple is 0.018A. Through analyzing simulative result, each parameter of four phase crisscross parallel Buck converter is in accordance with requirement of low voltage and high current DC-DC converter.The latter part of the thesis that design low voltage and high current power supply based on four phase crisscross parallel Buck converter simulative circuit. Adopting integrated chip HIP6301 of Intersil Company in the experiment, PWM pulse of four branches phases crisscross can be outputted, then a voltage regulation power is manufactured with output voltage 1.85V, rated current 10A. When the input voltage is 12V, output current is 10A and switching frequency is 130KHZ, the output voltage ripple is 33mV, regulation factor of load is 0.2% and efficiency of circuit is no less than 86% through testing experiment circuit. The experiment results show that the voltage regulation power which has high efficiency, rapid dynamic response and low output ripple voltage is implemented by adopting multiphase crisscross parallel technique, providing the reference and idea for achieving design of low voltage and high current power supply.