Small-Signal Modeling of Mutual Saturation in Induction Machines

Abstract

Abstract-A small-signal model is derived for saturated induction machines. Inductances are allowed to saturate as a function of their own current (or flux), and the mutual saturation effect originating mainly from skewed or closed rotor slots is also included in the model. The model fulfills the reciprocity conditions, and it can be applied to parameter identification and to the analysis and development of flux angle estimation methods. As application examples, the parameters of a 2.2-kW induction machine were identified using the data obtained from time-stepping finite-element analysis and locked-rotor measurements. The proposed model fits well to the data, and the fitted parameters are physically reasonable.

Validation of FEM-Based Parameter Estimation for Variable Phase-Pole Induction Machines

“…8 is not used in this case. The procedure and equipment used to perform the tests for the VPPIMs in [m = 3, p = 2] configuration are described in [22]. For the [m = 9, p = 2] configuration, a nine-phase inverter was used in both tests.…”

“…The NL test was conducted by turning the shaft with a prime mover at close to synchronous speed (≲ 1193 rpm). NL curves were captured to determine L σ,s and the unsaturated L m for each configuration using the s.c. the indirect method in [22]. The LR tests were conducted at a frequency of 10 Hz to mitigate the skin effect and the voltage was gradually increased until the rated current was reached.…”

A five-phase induction machine model using multiple DQ planes considering the effect of magnetic saturation

“…The unsaturated magnetizing reactance for the fundamental plane represents the slope of the linear part, while the saturated magnetizing reactance corresponds to the ratio between rated induced voltage and the corresponding no-load current. The saturated and the unsaturated magnetizing inductances of the third plane can be obtained using the simple relation given in (7). …”

“…However, induction machines usually incorporate a certain degree of magnetic saturation at rated operating conditions which challenges this generic complete decoupling assumption. Although saturation effects have been carefully addressed in the literature for three-phase induction machines [4][5][6][7][8][9][10][11][12], limited recent work has been reported in machines with higher phase order [13,14]. In [13], the effect of saturation on the air gap flux density waveform of five-phase induction machines was presented.…”

Online Identification of Parameters Defining the Saturation Characteristics of Induction Machines

“…The identification is based on a simplified small-signal model presented in [22], and the principle of the identification method is the same as in [23], but here, a current signal is injected instead of a voltage signal. At higher frequencies, the relation between the stator voltage deviations and the stator current deviations can be modelled using a small-signal impedance matrix according to…”