| Nowadays, with the requirement of high quality and reliable power system, UPS's ( Uninterruptible power supplies) are widely selected for the protection of sensitive loads such as PC, communication systems and medical equipments. Inverter is the core of UPS and is required to have high quality output waveform. With quick increase of the performance of DSP (Digital signal processing), Digital control are becoming more popular in inverter system.This thesis introduce the design of DSP control for three phase inverter, witch includes digital realization of PWM control, digital PLL, swap control between inverter and utility, and communication with MCU. Base on inverter model, inverter output L-C filter is investigated, and double-loop control scheme with TMS320LF240 are selected. The instantaneous voltage inner loop is used to control output voltage waveform to track a sinusoidal waveform. And the outer average voltage loop guarantees accuracy of output voltage. Both outer and inner loops adopt PI controller. Detail design of controller parameters, circuits and DSP software are given. In addition, we analyse the dead time effects of PWM control on the output waveform. In the end the experimental results are provided.
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