The Characteristics Calculation Research On The Three-phase Induction Motor Under The Supply Of Frequency Converter

With the important merit of saving energy for the timing system of three-phase induction motor under the supply of frequency converter, it has been widely used in more and more fields. Now, With the rapid development of power electronics and frequency-conversion technology, most frequency-conversion motors still are replaced with the common three-phase induction motors which are designed according to the supply of invariable frequency, invariable voltage and sine wave. The result brings about series of questions and restricts the advance pace for the whole system. As a result, more and more people take interest in the aspect, but there hasn't been an appropriate arithmetic for it. In this situation, the paper proposes a new calculation method to calculate thecharacteristics of the three-phase induction motor under the supply of frequency converter, and the experiments demonstrate its validity.The method uses the dipolar SPWM wave forming by the equal-area algorithm, with the high performance and the better ability of restraining harmonics. Firstly, the SPWM wave becomes the math-model of the power system after the Fourier transforms for it. Secondly, the complex math-model of three-phase induction motor and the three-phase power transform to the static direct-quadrature-axis by transformation matrix. Thirdly, using the equivalent circuit and bidirectional revolving-field theory of the single-phase induction motor with two stator windings in space quadrature, from the basal forming principle of the torque and other characteristics for the motor, it can deduce the common expression of the torque and other characteristics with the equivalent circuit parameters of three-phase induction motor. At last, the paper emulates all characteristics, and then the results transform to the three-phase coordinate axes by the reverse transformation matrix.In order to prove the validity of the method, the paper proposes the torque-speed characteristic test, vibration torque test, starting torque test, mechanical characteristic test of three-phase induction motor under the supply of frequency converter. These experiment results are compared with the emulation results, so that it proves to be valid from the results. On the base of its correctness, the paper compares the typical...