| The speed identification with rotor slot harmonic frequency is utilized in the motors with non-skewed rotors, but most of medium and small size induction machines use skewed rotors, and the skew angles are different and influence of harmonic power supply on rotor slot harmonic frequency should be concerned. Therefore, influence of skewed rotors and different skewed angles and harmonic power supply on speed identification accuracy should be studied systematically. Taking a 5.5kW motor with 4 poles as an example, influence of skewed rotors and different skewed angles and harmonic power supply on identification accuracy of rotor slot harmonic frequency has been studied by time stepping finite element method. The theoretical analysis in this thesis is verified by experiment. The main contents are as follows:1. Taking a 5.5kW motor with normal power supply as an example, influence of skewed rotors and different skewed angles and harmonic power supply on identification accuracy of rotor slot harmonic frequency has been studied by time stepping finite element method. Then, the theoretical analysis in this paper is verified by experiment on three kinds of motors with capacity of 3kW,5.5kW and 55kW.2. Then, taking a 5.5kW motor as an example, by adjusting the carrier frequency of frequency transformer to change the harmonic content of the frequency transformer output voltage. And influence of variable frequency power supply on rotor slot harmonic frequency has been studied systematically.3. Finally, taking a 5.5kW motor as an example, influence of harmonic power supply on rotor slot harmonic frequency has been studied when the power supply is with different content of harmonic under different loads. |
PDF Full Text Request