Numerical impulse response test to identify parametric models for closed-slot deep-bar induction motors

Abstract

An impulse response test for estimating the electrical parameters of a deep-bar induction motor is studied. The impulse response test is performed within the two-dimensional finite-element analysis (FEA). The impulse excitation is applied to the stator voltage. Since the test is suitable for modelling the perturbations about a certain operation point, a small-signal model for the double-cage induction machine is derived. The skin effect is taken into account by using two parallel rotor branches. In addition to the small-signal parameters, the steady-state parameters are also estimated using the time-harmonic FEA. The impulse response test is based on the assumption of linear behaviour about an operation point. Thus, the effects of nonlinearity are studied by several methods.

Small-signal model for saturated deep-bar induction machines

“…Parameters of a 37-kW squirrel-cage induction machine were estimated using the numerical impulse response test [13,18] based on the data obtained from time-stepping FEA [12]. The machine is equipped with deep rotor bars and closed rotor slots; the cross-section of a rotor bar is shown in Fig.…”

“…For comparison, the parameters obtained by fitting the conventional space-vector model 1 to the frequencyresponse data shown in Fig. 4 are also given; the only operating-point quantities used in the fitting were the angular frequencies ω s0 and ω r0 [13]. The fitted magnetizing inductance L m0 of the spacevector model is between the inductances L m0 and L mt0 of the proposed model.…”

“…The deviations of the inductancesL m andL rσ can be inserted into (13). Furthermore,ĩ s andĩ r can be solved from (13) and inserted into (12), leading to a linear multiple-input state-space representation…”

“…Finite-element models for electrical machines are computationally too demanding for many applications, such as comprehensive simulation models and control purposes, but the FEA can be used as a tool for providing the estimation data for small-signal model parameters. In [13], a small-signal model has been derived for deep-bar cage-induction machines, and the FEA-based numerical impulse response test has been used for parameter identification. However, the effects of saturation are not included in the model.…”

Untitled

“…Besides an accurate simulation method, the FEA can be seen as a tool for obtaining the circuit parameters etc. [29].…”