Research And Design On The Programmable AC Power Supply Based On DSP

AC voltage source is indispensable tool in the power laboratories and researchinstitutions. During research and product testing different AC power need be supplied formany tests carried out smoothly, according to different requirements of the output voltageamplitude, frequency and waveform. Therefore, the research and design of programmableAC power supply has a high value in engineering.Based on the DSP control, a programmable ac power with the power of1KW isdesigned in this paper. The AC-DC-AC construction is selected as the power main circuittopology. The power main circuit topology consists of the first single-phase PWM rectifiercircuit and the second single phase full bridge inverter circuit. The parameters for theinductance and capacitance in the system can be set reasonably through the analysis andcalculation of the range of parameters. The small-signal model of the first stage and thesecond stage of main circuit is derived to design parameters of the voltage and currentloop regulators by observing the open-loop frequency characteristics to meet sufficientstability and velocity of the system. PWM rectifier circuit adopts bipolar modulation, thecontrol scheme of DC bus voltage outer loop and the inductor current inner loop beadopted to realize the power supply input terminal operating in high power factor, in orderto enable a more rational design of AC power. DC bus voltage within a certain range inaccordance with the inverter output voltage amplitude improve the utilization of DCvoltage, optimized the output voltage waveform. For the second harmonic fluctuations onthe DC bus design a trap to prevent disturbances introduced into the feedback controlsystem leading to higher order harmonics. Inverter circuit adopts unipolar modulation, thecontrol scheme of output voltage outer loop, the inductor current feedback and loadcurrent feedforward inner loop, the system has a higher bandwidth and achieve widevoltage range and broad frequency, with the function of analog voltage surges, suddenreduction and it can be superimposed within20harmonic to analog the output voltagedistortion.The main circuit experimental platform is built after the PSpice simulation the entire power system. The TI Company’s digital signal processor TMS320F2812is selected as thecontrol chip of the control circuit. By compiling C language program, the prototype of theAC power supply be finished. The experiment results verify the feasibility andeffectiveness of the control strategy.