Generating 3-phase modulation signals for variable speed AC drives using the TMS320c26 DSP chip

This paper describes a motor drive controller for a three-phase PWM voltage source variable speed inverter drive using a TI TMS320c26 digital signal processor (DSP). By choosing different reference signals, many kinds of PWM strategies can be implemented using the same principle as the normal sinusoidal PWM. A method is developed to use the single timer in the DSP to generate 3-phase PWM signals, to realize the minimum dwell time control, and to perform variable speed control. All the timing signals associated with the pulse width modulation, signal generation and motor speed control functions are implemented using DSP assembly language software. As a result, minimal hardware is required, and the controller has high flexibility and reliability