Research On Digital Single-phase Inverter Power Supply Optimization Control Technology

In the early development of the inverter,the analog circuits and open-loop control are widely used because of the simple circuit structure and the low cost,but the output voltage waveform was significantly distorted and has the high total harmonic coefficient(THD),the output voltage waveform is evidently affected by the load and can not control.Therefore,in the circumstances of the low output voltage quality requirements,an open loop control system maybe used,while in the occasions of the high power quality requirements,a closed-loop control system must be used.With the development of the digital signal processors(DSP),the digital circuit design of the inverter power supply is possible.The digital control system has high reliability,simple hardware circuit structure,could realize real-time control and many kinds of control algorithms conveniently.In this paper,after the three sinusoidal pulse width modulation(SPWM)ways of the single-phase full-bridge inverter circuit were analyzed theoretically and compared by the simulation,the unipolar multi-fequency SPWM modulation way was chosen.In order to achieve the digital control of the inverter power supply,the regular sampling method and the natural sampling method are analyzed.The digital control system of single-phase full-bridge inverter power supply is simulated and researched in this article.The output voltage waveform of the single?phase full-bridge inverter power supply is as controlled volume and reference standard in this digital control system,PID control outer loop and instantaneous repetition control inner ring form a double closed-loop control system together.In a double closed-loop control system,the PID outer ring is the mean control system,the inner loop of the instantaneous repetitive control is a servo control system.Among them,the outer loop controller can adjust the given value of the inner loop controller according to the change of the load,this double closed-loop control system has ideal voltage output,fast dynamic response and high steady-state performance,so the output voltage waveform of the single-phase full-bridge inverter power supply has been improved greatly.TMS320F2812DSP is regarded as the core of the digital control system,being familiar with the design of the total hardware circuit and software program,including the main circuit of the inverter power supply,the power supply structure,the drive circuit,the protection circuit and the filter circuit and so on.The modular program structures are used in the software design,including the main program,the A/D,the SPWM waveform generator and the other subroutine modules.Finally,the TMS320F2812DSP was used as the control chip in the experimental platform,completing the debugging of the digital control system.The experimental results show that the digital control system could produce the ideal output voltage waveform,the feasibility and effectiveness of the control system are proved.