1990 Fiscal Year Final Research Report Summary
Instability in InverterFed Induction Motor Drives
Project/Area Number  01550345 
Research Category 
GrantinAid for General Scientific Research (C)

Allocation Type  Singleyear Grants 
Research Field 
計測・制御工学

Research Institution  Daido Institute of Technology 
Principal Investigator 
MATSUBARA Masakazu Daido Institute of Technology, Department of Electrical Engineering. Professor, 工学部, 教授 (60022969)

Project Period (FY) 
1989 – 1990

Keywords  induction motor / stability / Routh criterion / bifurcation theory / tangential bifurcation / Hopf bifurcation 
Research Abstract 
In the inverterfed induction motor drives an instability accompanied by speed fluctuations appears often in lightload and lowspeed operations. This is caused not by the introduction of the inverter but by the induction motor itself. This phenomenon is such that an equilibrium point becomes unstable as the operating condition is varied and that a stable limit cycle appears around the equilibrium point. So, from the bifurcationtheoretical standpoint, this is to be dealt with as the Hopf bifurcation. However, only a few investigations based on such a standpoint have been reported so far. In this work the stability of an induction motor driven by a variableamplitude and variablefrequency sinusoidal voltage source is investigated from the bifurcationtheoretical standpoint. The entire bifurcation set is determined in the parameter space of the frequency, slip and load torque. The following points were made clear : (1) Only four types of the hyperbolic equilibrium point, that is, _0PD, _1ND, _2PD and _3ND appear. Of these four, only the _0PD type is stable. (2) The tangential bifurcation takes place at the peak point of the torquespeed curve. _0PD and _1ND types appear in the lowerslip side (statically stable side) of the tangential bifurcation set while _2PD and _3ND types do in the other side. (3) The Hopf bifurcation accompanied by limit cycles takes place at the boundary of _0PD and _1ND regions and at the boundary of _2PD and _3ND regions. Stable limit cycles are observed within the _1ND region. (4) The tangential bifurcation set is distorted by the saturation so as to enlarge the statically stable region. (5) The Hopf bifurcation set is composed of three manifolds, but only the one located in the highestslip side remains when the magnetic saturation is disregarded.

Research Products
(2results)