Impact of Core Sheet Cutting Method on Parameters of Induction Motors

Abstract

The method of cutting motor core sheets causes a change in their magnetic properties and core losses, especially additional losses. Reducing motor losses is very important because of the fulfillment of increasingly stringent requirements set by international regulations for reducing electricity consumption. Due to fact that more and more often induction motors are supplied with high-frequency voltage, core losses are beginning to play a dominant role in the motor’s loss balance. That is why accurate determination of these losses is very important and cutting has a significant impact on them. This report shows how the method of cutting sheet metal affects losses in the finished induction motor working in a wide frequency range. The paper presents the impact of various motor core fabrication technologies on its operational parameters and an approximate way of including this impact in analytical calculations at the design stage of new machine designs, as it is necessary to use sheet metal cutting technologies such as laser or electrical discharge machining (EDM) at the prototype stage. The proposed method is based on measurements of sheet parameters made on toroidal samples with appropriately selected dimensions, so that the width of the sample corresponds to the average width of the motor core elements.

3D Electromagnetic Field Analysis Applied to Evaluate the Accuracy of a Voltage Transformer under Distorted Voltage

“…The magnetic core of this VT is made from cold-rolled steel sheets and composed of two parts connected together in the middle of the windings. electromagnetic devices such as motors [7], power transformers [8], instrument transformers [9], and other types of converters. It was used both in the design of magnetic circuits [10] and insulation [11,12], as so in steady states as in transient, when supplied with direct and sinusoidal current.…”

“…The analysis was performed using the 3D field-circuit method by coupling Maxwell's equations in the area of the tested object with the equation for circuit outside the area (the load connected to the terminals of the modeled device) [7,10,21]. This enables to calculate the currents and voltages induced in the secondary circuit.…”

“…The boundary conditions are A × n = 0 and V = 0 at the boundary of the whole system with the surrounding air. The secondary voltage is determined and compared with the same secondary voltage of load circuit Equations (3) and (4) or (6) and (7).…”

Correlation between Cutting Clearance, Deformation Texture, and Magnetic Loss Prediction in Non-Oriented Electrical Steels

“…Among the works on the processing of electrical steels by means of cutting, attention is given mainly to the influence of the cutting procedure (e.g., mechanical, laser, water) on magnetic behaviour [17][18][19]. Previous approaches to identify the characteristics of the cutting process play a crucial role in the optimization of the sheared edge quality investigated the links between various mechanical and geometrical properties such as the burr height, the wear of the cutting tool, and the thickness of a sheet [20,21].…”

Parameter Estimation of Inter-Laminar Fault-Region in Laminated Sheets Through Inverse Approach

“…The manufacturing process of electrical machines that includes punching/cutting, core assembly, and welding induces mechanical and thermal stresses to the electrical steel sheet. The induced stresses cause degradation of the magnetic properties of the laminated steel sheet around the cutting edge and the welded region [1][2][3][4][5], which has a direct impact on the core losses of the final manufactured electrical machine. Furthermore, the mechanical stress during the punching process inevitably causes burr on the cut edge of the steel, when the sheets are stacked and welded together to form the machine core, can lead to the formation of an inter-laminar short circuit fault between laminations.…”