Comparative Analysis of Line-start Synchronous Motor and Asynchronous Motor

Abstract

Energy efficient motors are the key components of each industrial process. In the energy demanding society, requiring the energy efficient consumers, the line-start synchronous motor has gained more and more popularity due to the high efficiency and power factor combined with good operational characteristics. The disadvantages of the synchronous motors such as inability of starting without the inverter has been largely overcame with this type of the motor. However, the proper design of line-start motor regarding permanent magnets and the squirrel cage winding is crucial for motor starting and synchronization capability. In this paper, the line-start synchronous motor is derived from the asynchronous motor by redesigning the rotor. The obtained performance characteristics of the synchronous motor is compared with the data of the asynchronous motor (the analytical, measurements and from the motor producer) and they show reasonable agreement. The derived model of the synchronous motor is numerically modelled for obtaining the magnetic flux density distribution in the motor cross-section. The analysis and comparison is completed by obtaining the transient characteristics of both types of the motors. The designed synchronous motor has proven to have good starting and synchronization capabilities combined with the high efficiency. The dynamic response at sudden load changes is within expected limits.