Reduction of speed and torque ripples caused by inverter dead time in permanent magnet synchronous motors

Permanent Magnet Synchronous Motors (PMSMs) are widely used in industrial automation and electric vehicle systems due to their advantages of high efficiency, torque density, and dynamic performance. Field-Oriented Control (FOC) algorithms are preferred for the precise control of these motors. However, these algorithms cannot always provide the desired performance due to dead time, one of the nonlinear effects in the system. Dead time refers to the intentionally added delays for the safe operation of inverter switches, which lead to distortions in the motor's current waveforms, torque ripples, and speed instabilities. This thesis investigates the torque and speed distortions caused by dead-time-induced voltage deviations in PMSM systems and proposes a compensation algorithm to mitigate these effects. First, the mathematical model of the motor is established, and then the field-oriented control structure is detailed. The developed algorithm was modeled in the Simulink environment and tested under various speed and load conditions. The study compares constant correction, adaptive voltage feedback, and observer-based compensation methods. It demonstrates that the proposed method significantly reduces torque ripples and the Total Harmonic Distortion (THD) rate. The developed algorithm is applicable in real-time systems without the need for additional hardware and with low computational cost. In this respect, this thesis contributes to the literature by offering software-based solutions to mitigate the detrimental effects of dead time.