Design Of Sliding Mode Controller For DC-DC Converter Based DSP

DC-DC converter is used widely in communications, computer, consumer electronics. The requirement of electronic devices to power supply is more and more high with the development of science and technology. For instance, consumer electronics need to use portable power supply which possesses voltage stability, little resistance and good dynamic performance. So the research of the power supply with high performance which is based on the power electronic technology and meets the requirements of all walks of life has been the main direction of the study of modern power supply. Based on the analysis of the topologies structure of DC-DC converter and the frequent modeling methods, the control theory of sliding mode variable structure was applied to the design of DC-DC converter. A sliding mode control DC-DC converter based on DSP was designed. The main work is as follows:First of all, the advantages and disadvantages of linear DC-DC converter control strategy and nonlinear control strategy and the analog and digital control technology of DC-DC converter have been introduced. DC-DC converter of the Buck converter, Boost converter, Buck-Boost converter as an example, the characteristics of the topology structure and several common modeling methods, and the limitations of using these methods in the design of DC-DC converters have been analysed.Secondly, the sliding mode control theory has been analyzed. The sliding mode control theory is applied to the Buck converter according to the DC-DC converter is a kind of nonlinear time-varying systems. A sliding mode control method with fixed switching frequency based on PWM modulation is proposed. The method not only reduces the switching frequency, but also solves the impact on the performance of sliding mode controller by the conversion speed of switch. The whole system includes the main power circuit, detection circuit inductance current, capacitance current detection circuit, DSP control circuit.Finally, we complete the test of the whole system. Experiment results show that variable structure sliding mode controller based on PWM technology solve the switch speed limit on the influence of the sliding mode variable structure controller. The system has good robustness, high control precision and fast dynamic response when the system parameter changes.