Research On High Precision And Programmable Power Supply

This dissertation introduces the research of high precision and programmable power supply based on the AVR MCU, Which not only aims at the requirement of power supply used in instruments, but also observes the design principles of green power supply, in which energy-saving and environment protection is required. The output is 0～60V/0～12A,when it works at the constant voltage mode and is constant current mode respectively. The ripple is less than 5mV.The merit and demerit of switching power supply and linear power supply is compared in this dissertation. On this base, The combined type voltage-stabilizing scheme is brought forward. It maintains the differential voltage of adjusting transistor invariable. So the waste of transistor itself is reduced, the performance requirement of transistor lowered, the conversion efficiency of power supply is also advanced at the same time.The technologies of EMI filtrate, APFC, combined type voltage-stabilizing scheme and third class active filter network are adopted in the part of power circuit. EMI filtrate technology is adopt to leaches the high frequency noise came from electric network. Active power-factor correction technology is adopted to improve the power factor. It makes aberrant input current tags the input voltage close to ideal sine wave. The aberration is resulted by the existence of input leading load. The disturber towards the electromagnetic environment around is reduced at the meantime. The combined type voltage-stabilizing scheme is adopted to reduce the waste of transistor itself and advance the conversion efficiency of power supply. Second class active filter network is adopted to leaches the ripple of output voltage further.The special EDA design software of power supply-saber is adopted to simulate each circuit module of power part. This design software is product by America Synopsys corporation, power function is possessed. This system is also verified by the experiment. The result indicates that this design not only realizes the high stability of output, but also realizes energy-saving and environment protection, conform the principles of modern power supply's design.