The Study Of Digital Control For Switching Converter

The control technique of switching converter is based on its model. As the switching regulation system is a high order, discrete, nonlinear, time-varying, ill-conditioned control system and difficult to build exact resolution model. The traditional control technique is for low frequency small-signal, so it's maybe unstable for big-signal systems. The nonlinear and other advanced control strategies for the switching converter have gotten more and more attentions, but it's too hard to realize those strategies on analog circuits. So it's meaningful to study the digital control of switching converter both in technique and practice. Taking the Buck converter for example, this paper deeply analyzes and studies on analog and digital control of the switching regulation system.Analog control is the traditional control method. Based on conversation of energy, this paper studies the non-ideal converter model at the continuous conducting mode, builds the small signal precise model of the Buck converter and validates the veracity of the model in experiment and simulation by the three-terminal switching device model. On this foundation, the paper simulates and experimentally studies the voltage control and peak current control switching modulation system and gets useful research results.Switching converter is developing to high frequency, modularization, digital and green, so the digital control is the developing direction of high frequency power switching converter. Now a lot of scholars and investigators are studying on the whole digital control of the switching converter, and the core is the control strategy. According to the traditional control's problem that overshoot and regulating time are not mutual coordination, this paper deduces the control arithmetic when the load increases or decreases suddenly based on the capacitance balance principle. The simulation and experiment results indicate that this control arithmetic improves the dynamic performance of DC-DC converter effectively.The hardware design of main circuit and control circuit will affect the running performances of the switching converter directly. This paper introduces the hardware design of the main circuit, control circuit, sample adjusting circuit, digital driving circuit and assistant power supply of switching converter's digital control system. An experimental prototype of switching regulation digital control based on the DSP of TMS320F2000 is developed and its output power is 60W. This prototype can be used as an experimental platform for the new advanced digital control strategy. Base on this prototype, the paper introduces the flowchart of the software design by C including soft-starting, digital PI control and capacitance charge balance control for the switching converter, the finished research of the digital control experiments, analyzes and compares the experiment data and gives the corresponding conclusion.