Study of the propagation of the modulator and transistors dead time in sensor-less AC motor drives based on SVPWM

An accurate model in order to simulate a nonideal inverter is complex. In this work, a Simulink model is proposed. The model implements all the structure of the power inverter and the nucleus of calculation of the modulation of the inverter to obtain the induction motor voltage. This paper also studies the feasibility of knowing the specified voltage by building the signal from the control signal that the modulator sends to the inverter. The interest is double. First, the goal is to know the limit of neglecting the dead time. In the other hand, to reduce the cost in sensor-less AC drives. The voltage measurement part in the sensor-less drive can be omitted if the studied system is implemented. The results show three main conclusions. First, the influence of the modulator is a pure delay for any modulation index and for any frequency. For nearly all applications, this delay (Tpwm) can be accepted. Second, the blanking time causes more relevant deviations, especially for lower modulation indexes. In this paper, a modulator compensation is suggested to improve the behaviour of the inverter in sensor-less applications. The results have been experimentally verified. Third, the response of the sensor-less system implemented with a modified system of voltage measurement is better than the systems that do not use modified models.