Magnetic circuit

About: Magnetic circuit is a research topic. Over the lifetime, 15707 publications have been published within this topic receiving 118099 citations.

Adaptive partial feedback linearization of induction motors

Abstract: A nonlinear adaptive state feedback input-output linearizing control is designed for a fifth-order model of an induction motor which includes both electrical and mechanical dynamics under the assumptions of linear magnetic circuits. The control algorithm contains a nonlinear identification scheme which asymptotically tracks the true values of the load torque and rotor resistance, which are assumed to be constant but unknown. Once those parameters are identified, the two control goals of regulating rotor speed and rotor flux amplitude are decoupled. Full state measurements are required. Preliminary simulations show that a good performance is maintained when flux signals are provided to the adaptive control algorithm. >

Modeling of a linear PM Machine including magnetic saturation and end effects: maximum force-to-current ratio

Abstract: The use of linear permanent-magnet (PM) actuators increases in a wide variety of applications because of their high force density, robustness, and accuracy. These linear PM motors are often heavily loaded during short intervals of high acceleration, so that magnetic saturation occurs. This paper models saturation and end effects in linear PM motors using magnetic circuit models. The saturating parts of the magnetic circuit are modeled as nonlinear reluctances. Magnetomotive forces represent the currents and the magnets. This paper shows that when saturated, a negative d-axis current increases the force developed by the motor. Although the increase is not large, it is nevertheless useful, because a negative d-axis current also results in a decrease in the amplifier rating. Further, the trajectory for the maximum force-to-current ratio is derived. The correlation between the calculated and the measured force justifies the model.

An improved magnetic equivalent circuit method for predicting the characteristics of highly saturated electromagnetic devices

Abstract: The magnetic equivalent circuit (MEC) method has been used to model the nonlinear magnetic field in electromagnetic devices for steady-state and dynamic conditions. However, for highly saturated electromagnetic devices, the conventional MEC method is inaccurate in predicting device characteristics. With experience gained from the finite element (FE) method, the MEC method can be modified to provide significant accuracy improvement in the field solution results. The main modification is done in the modeling of the highly saturated regions. The improved magnetic equivalent circuit (IMEC) is used to predict the characteristics of a switched reluctance motor (SRM). The results from IMEC are compared with those obtained by conventional MEC, FE methods and measurements.

Investigation and General Design Principle of a New Series of Complementary and Modular Linear FSPM Motors

Abstract: The conventional linear flux-switching permanent-magnet (FSPM) motors directly split from a rotary FSPM motor suffer from drawbacks such as unbalanced magnetic circuit of end coil, bigger cogging force, and force ripple. In this paper, to reduce cogging force and thrust force ripple, some complementary and modular linear FSPM (LFSPM) (MLFSPM) motors with mover/stator pole pitch ratio τm/τs of about one, namely, τm/τs = 10/12, 11/12, 12/12, 13/12, 14/12, 15/12, will be investigated using finite-element method (FEM) and experimental method at first. Then, another new LFSPM motor with τm/τs = 3 is analyzed. Based on τm/τs = 3, some new MLFSPM motors are designed, investigated, and compared using FEM. To fully investigate these motors, the optimal MLFSPM motor with τm/τs = 3 is quantitatively compared with the two optimal motors with τm/τs ≈ 1 . Finally, the general design principle for this series of MLFSPM motors with different τm/τs values is concluded.

A new approach to calculating core losses in the SRM

Abstract: In the switched reluctance motor, the flux waveforms are nonsinusoidal and different parts of the magnetic circuit have different waveforms. This paper presents a new approach to taking into account these flux waveforms in the calculation of core losses. Relations between the fluxes of different parts of the magnetic circuits are given in the form of matrix equations, where the fluxes are expressed in terms of normalized flux pulses. Rewriting the eddy-current loss term in the Steinmetz equation in terms of the square of dB/dt and combining it with the matrix equations, eddy-current losses for the complicated flux waveforms of the stator and rotor yokes are calculated. The effect of PWM is taken into account by considering the PWM voltage waveform as dB/dt. From the matrices, it is easy to count how many times the full and minor hysteresis loops occur at each pole and yoke segment. The effect of the minor loop is taken into account based on experimental results. The proposed approach gives a systematic procedure for the core loss calculation. The derived equations are simple and useful for the design of the SRM. >