| Controllable AC power supply is a device which converts the input AC power into sine wave power with required frequency, voltage and current through power conversion circuit. In the electrical laboratory, some experiments need specific AC power, the industrial frequency transformer is not able to meet the needs any more. Therefore, this paper presents a controllable AC power design based on digital signal processor, and through the system test, the system can export desirable sine wave power with adjustable voltage, current and frequency. The input of controllable AC power supply is220V/50Hz single-phase AC power, the output mode can change in the mode of voltage and current, the amplitude is adjustable and the frequency changes in50Hz and60Hz.This paper introduces the fundamental principle, structure of the system and the determination of final solution at first. Then, it presents the design of the hardware. The hardware can be divided into two parts, the main circuit and the control circuit. The main circuit includes rectifier circuit, input filter circuit, inverter circuit, IGBT snubbed and protection circuit, and output filter circuit. The control circuit includes isolation and driver circuit, sampling and conditioning circuit, auxiliary power supply circuit and LCD circuit. Moreover, the paper introduces how to select the components of every circuit through calculation. Then, it introduces the software design which can be divided into some modules in detail, including the generation method of SPWM, the A/D sampling subprogram, the incremental PI algorithm subprogram, LCD subprogram and so on. The flow chart of every subprogram is also provided.Finally, the paper gives some photos of the power supply and presents some tests for the output. The waveforms of the control signal and the close-loop output, the function tests of amplitude and frequency show the performance of the system fully and prove that the power supply is stable and reliable and the design is feasible. |
PDF Full Text Request