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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.

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This paper studies a modular permanent magnet synchronous machine (MPMSM) converted from a traditional single-core 24-slot 20-pole tooth-coil winding permanent magnet synchronous machine (TCW PMSM). The performance of the TCW PMSM is compared with the performance of the MPMSM (rearranged from this TCW PMSM) by the finite element method (FEM). It is found that if an electrical machine with a modular structure is designed, the efficiency of the MPMSM may be degraded compared with the conventional structure, especially, if a solid rotor yoke is used. However, the advantages of the proposed MPMSM are related to an option to scale up the machine by applying a certain number of modules, or removing faulty modules (while keeping the healthy modules working). This makes this type of a motor design applicable in certain life-critical applications, or in applications where scaling of the motor power might be needed. As a prototype, a low-power, low-speed generator added to a hook block of a hoist to supply power to measurement electronics is studied.

Numerical impulse response test to estimate circuit-model parameters for induction machines.Abstract: The estimation of electrical parameters of a cage induction machine is studied. First, the steady-state parameters are estimated using two-dimensional finite element analysis (FEA) with the assumption of sinusoidal time variation. Next, a numerical impulse response test using timestepping FEA is utilised to produce the voltage-current data for the small-signal model parameter estimation. The method is based on the assumption of linear behaviour near the operating point and the choice for the suitable excitation signal is studied. To distinguish the influence of the skin effect, the impulse response test is also performed for the corresponding slip-ring machine. The parameters are estimated from the frequency response function of the stator line current using differential evolution. The results of the FE simulations are compared with measurements.