Executive Summary : | The objective of this project is to design and development of multi-level inverter (MLI) fed multi-phase (M-ɸ) sensorless permanent magnet synchronous motor (PMSM) drive with reduced torque and flux ripples, as well as reducing current and voltage harmonics, and smooth vector switching intended for hybrid electric vehicle (HEV) applications, where the maximum average torque with a minimum torque ripple is demanded over a wide speed range of the machine. The three-phase (3- ɸ) power supply systems are no longer limited for motor drive control system. The M-ɸ motor drive system has higher fault tolerance, provide less torque ripple contents, and making M-ɸ motor drive systems are more capable for high performance and reliability instances over 3- ɸ motor drive systems. Therefore, a five-phase (5-ɸ ) PMSM motor drive system is considered in this project as it provides less torque ripple contents, higher fault tolerance and reliability which are essential for HEV applications. The conventional DTC (C-DTC) of a PMSM drive offers fast dynamic response as the torque and flux are controlled directly by selecting appropriate voltage vectors. However, the C-DTC method employs hysteresis comparators and switching table to get quick dynamic response, which causes large torque and flux ripple. In the literature, several methods have been proposed to reduce flux and torque ripple by optimizing the duty ratio of active voltage vectors. However, these methods are usually complicated and parameter dependent. Some of them have employed SVM to produce continuous voltage vectors, which can adjust the torque and flux more accurately and moderately. Hence, flux and torque ripple are minimized while obtaining constant switching frequency. The torque and flux ripples in DTC-SVM drives can be attenuated if a MLI is employed instead of two-level inverter, because the MLI capable of synthesizing output voltages with several discrete levels. The neutral point clamped (NPC) based MLI are used in variable speed DTC drives, which gives good performance. The DTC-SVM method requires precise rotor speed or position information for accurate speed control. However, mounting a speed sensor on the motor shaft has several drawbacks such as space limitations, increasing cost, and size. In order to overcome these drawbacks and to further enhance the performance of the 5-ɸ PMSM drive, the rotor speed is estimated using MRAS based speed estimator scheme. The proposed project is simulated in MATLAB/SIMULINK to test the feasibility and effectiveness of the system under different operating conditions. The simulation results will be validated with the experimental results by developing a laboratory based prototype systems. |