Jacek Mikołajewicz and Lech Nowak
The aim of the paper is to find the effective methods of power loss reduction in axisymmetric electromagnetic devices and improve their dynamic parameters. As an example the…
Abstract
Purpose
The aim of the paper is to find the effective methods of power loss reduction in axisymmetric electromagnetic devices and improve their dynamic parameters. As an example the linear tubular motor is considered.
Design/methodology/approach
The elaborated algorithm has been applied to analyze the dynamic operation of axisymmetric electromagnetic devices, especially tubular linear induction motors. The mathematical model of transients includes: the equation of electromagnetic field, the equations of electric circuits and the equation of motion. The model is based on the finite element method. For the time‐stepping, the Cranck‐Nicholson scheme is applied. In order to include non‐linearity, the Newton‐Raphson process is adopted.
Findings
In order to reduce the influence of eddy currents, it is suggested that the solid core should be equipped with one or several radial slots. In such a case, the radial component of eddy currents occurs near the slot and disturbs the axial symmetry of the system. However, when the width of the slot is small, the fields generated by the radial component of eddy currents on both sides of the slot practically cancel one another and the system can still be considered axisymmetric. Another solution given in the paper consists of replacing the cylindrical core with a system of flat laminated segments. In such a case, saturation of the ferromagnetic parts is greater than in the case of classical axisymmetric core.
Originality/value
In the paper, new quasi‐2D axisymmetrical field‐circuit methodology for electromagnetic device dynamics analysis has been elaborated. Proposed constructional solutions enable one to reduce the power losses in the primary core by half and total losses by 30 percent.
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Lech Nowak and Jacek Mikołajewicz
This paper presents a coupled field‐circuit simulation of transients in a non‐linear electromagnetic device supplied by electronic power converters (inverters, PWM systems). The…
Abstract
This paper presents a coupled field‐circuit simulation of transients in a non‐linear electromagnetic device supplied by electronic power converters (inverters, PWM systems). The eddy currents induced in solid cores are considered. The mathematical model of transients includes: equation of electromagnetic field, equations of the electric circuits and equation of motion. Numerical implementation of the algorithm is based on the finite element method. For time‐stepping the Cranck‐Nicholson scheme has been applied.
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Keywords
The aim of this paper is to analyse the influence of various methods of controlling a stepper linear reluctance motor on the dynamic parameters of this motor.
Abstract
Purpose
The aim of this paper is to analyse the influence of various methods of controlling a stepper linear reluctance motor on the dynamic parameters of this motor.
Design/methodology/approach
Construction, principle of working, and mathematical model of a four‐band stepper linear reluctance motor are shortly discussed. In order to elaborate an effective tool for motor performance analysis, a circuital approach was applied. To increase model accuracy, major parameters of the model (main self‐ and leakage inductances) were calculated on the basis of a 3D electromagnetic field distribution using Finite Element Method (FEM). The nonlinearity of the core was taken into account. Elaborated mathematical model was implemented in MatLab‐Simulink environment. Selected results of investigations are presented.
Findings
The elaborated mathematical model and the review of control methods are very useful for analysis of dynamic operation of stepper linear reluctance motors.
Originality/value
The paper provides a review of control methods of stepper linear reluctance motors.