Based On Energy Optimization Of The Model Psm Control Circuit Design And Realization

At present, pulse skip modulation (PSM), is widely used in power integrated circuits (PIC). It can overcome low conversion efficiency of pulse width modulation (PWM) and random spectrum distribution of pulse frequency modulation (PFM). PSM has many merits such as high efficiency at light load, high response speed, robustness and ease of implementation, which are proved by theory analysis and simulation. However, PSM also has some disadvantages: large output voltage ripple and audio noise at light load.This dissertation gives energy balance model (EBM) for boost converter. Based on EBM, the bifurcation parameters of conventional PWM converter and stability of PSM converter are analyzed. The operation of optimized PSM is also studied. A controller chip of boost converter is designed, taped out and tested after packaged.The detailed works are listed as follows:1) Efficiency and output voltage ripple analysis of PSM operating at discontinuous current mode (DCM), and compared with that of PWM and PFM;2) Based on EBM of boost converter, bifurcation and chaos phenomena of PWM converter are studied, a stability estimation rule with energy dimension is proposed, and all the bifurcation parameters can be described in consistent energy dimension;3) Based on EBM of boost converter, the characteristics of PSM and optimized PSM are given. And the stability of PSM converter and low output ripple are proven;4) The medial duty cycle of optimized PSM converter is given according to output ripple and load range, and the key sub circuits to implement the control scheme are designed, including current sensing and current limit comparator;5) A controller with optimized PSM is designed. The chip is taped out in CSMC by 2P3M mixed signal process. Test results after package show that the output voltage is 3V, the output ripple is less than 30mV, the efficiency is above 80% in the whole load range and its maximum value is 84%.