This is a bi-polar PWM inverter to generate a sinusoidal output. A PI controller is implemented by the DSP to keep the output voltage as sinusoidal as possible in the case of a non-linear load, i.e. rectifier. The sinusoidal wave is generated based on a pre-defined look-up table. The output signal is continuously sampled by ADC which is triggered by EPWM module. The error signal is then calculated based on the difference between the reference voltages in the look-up table and the sampled output voltage. The PI controller modifies the look-up table accordingly to minimize this error. As a result, any non-linear load will have minimal impact on the output sinusoidal wave.
The controller is capable of receiving commands through UART and changing the amplitude of the output sin wave accordingly, or turning the inverter ON or OFF. It uses the ADC, EPWM and UART interrupts to avoid any interference between the UART module and the PI controller.