Impact of PWM Strategy on Current Estimation Quality in Induction Motor Drive System

In modern electric drives, the aim is to provide the best possible control while ensuring safe operation. Diagnostic methods that are used for the latter purpose require the use of signals to identify failures in the operation of the drive. For this reason, methods are being developed that reproduce state variables with high accuracy. One signal that can be estimated is the stator phase current, which should be known in any control structure of the electric motors, especially in the case of current sensor fault. However, current estimators based on the mathematical model of the motor are sensitive to incorrect identification of object parameters. One method to improve the quality of estimation is to use an inverter dead-time compensation algorithm. However, there is a lack of research on the effect of the chosen pulse-width modulation (PWM) technique on the performance of the current estimator. This article presents the results of such a study, which was conducted on a laboratory test bench in a drive system with an induction motor. The effect of ten different modulation techniques on the quality of stator current estimation in a drive system with inverter dead-time compensation taken into account was studied. The results confirm that the selection of an appropriate PWM modulation strategy can improve the quality of estimation by up to 36.7% over the commonly used space-vector PWM (SVPWM). The results of the study can be the basis for the development of algorithms to improve the quality of stator current estimation over a wide range of drive operating points.