Design Of Variable Frequency Power Supply Based On DSP

Variable frequency power supply should not only has higher performance of steady-state, but also has fast dynamic response. The digital control technology based on variable frequency power supply can meet these requirements effectively. In view of the actual demand, this thesis designed a frequency conversion power which used the DSP as control core, and input is single-phase alternating current, output voltage and frequency were adjustable.Through in-depth study of the related theory of variable frequency power supply and analyzing the basic principle of variable frequency power supply, the theories of sine pulse width modulation technology, dead time effect and compensation method, the digital PID control technology, the paper determined the performance parameters of the system and the design scheme of system structure based on the actual engineering requirements. The main circuit used the voltage source AC-DC-AC structure, and optimized the circuit parameters to achieve the requirements of low pressure on switch tube and small ripple of the output voltagel. In order to improve the input power factor and reduce the current harmonics, rectifier circuit adopted the active power factor correction technology to stable the output voltage, make the input current close to sine wave. Single phase full bridge inverter circuit based on DSP used the digital control strategy which give the method for the generation of SPWM waveform, the control algorithm of AD sampling and the PID regulated to realize the flexible control of variable frequency power supply, at the same time improving the dynamic performance of overall system. The APFC circuit and inverter circuit simulation model were set up through the saber and MATLAB/Simulink software, then the experimental results of the system were analyzed by simulating which verified the correctness and effectiveness of the system design scheme.Circuit simulation results showed that the waveform of the input current followed the input voltage waveform well and the power factor was up to 0.97 which met the demand of the system. The output voltage of rectifier circuit stabilized at 400 V and inverter circuit realized the function of VVVF.