Comparison of Induction Motor and Line-Start IPM Synchronous Motor Performance in a Variable-Speed Drive

This paper presents an in-depth comparative analysis of the variable speed drive (VSD) performance between an IEC frame size 90 four-pole three-phase induction motor (IM) and the equal line-start interior permanent magnet synchronous motor (LSIPMSM). Employing measurement data from no-load tests, load tests, and temperature-rise tests of the aforementioned motors and different cage materials as well, the motors´ no-load and load characteristics are first examined in detail and then the drives´ characteristics are analyzed in open-loop volts per hertz (V/f) control by using the same voltage-source inverter and the aforementioned IM or LSIPMSM in both constant torque and constant power operation. It has been established that particularly the motors´ current and power factor characteristics have distinct impact on the consequent VSD performance in terms of loss and efficiency. Furthermore, it has been shown that the lower loss of the LSIPMSM enables a significant increase of the VSD´s constant power range.