Resistance Module for Electric Machine Runup Torque
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Solution Overview
Problem
Existing solutions for increasing runup torque in electric machines with rotor windings are limited in effectively reducing runup current and enhancing startup dynamics.
Innovation Solution
A resistance module comprising at least two electrically-conductive layers made of resistive material, connected in series with a rotor winding, which surrounds the axis of the electric machine, providing increased electrical resistance to reduce runup current and enhance startup torque, while ensuring good heat dissipation and mechanical robustness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If a rotor winding with large electrical resistance is used during runup, then runup torque increases, but runup current increases
Solution Approach 1:
The resistance module is divided into multiple electrically-conductive layers connected in series, each layer contributing to the total resistance. This segmentation allows precise control of resistance value while managing current flow through distributed layers, resolving the contradiction between needing high torque (high resistance) and limiting runup current.
Solution Approach 2:
The resistance module is positioned specifically in the exciter circuit path during runup, providing localized resistance only where needed. The layered structure with insulating layers between them creates local electrical properties that increase torque without uniformly increasing current throughout the entire rotor winding system.
2Use of energy by moving object
If multiple electrically-conductive layers are used in series, then electrical resistance increases to reduce runup current, but device complexity increases
Solution Approach 1:
Multiple electrically-conductive layers are merged into a single compact resistance module assembly. The layers are stacked with insulating layers between them, creating an integrated structure that functions as one component rather than separate elements, thereby reducing overall device complexity while maintaining the series connection for increased resistance.
Solution Approach 2:
The electrically-conductive layers are nested within the resistance module structure, with each layer contained within the modular assembly. This nesting approach consolidates multiple resistance elements into a single space-efficient unit, reducing the complexity of wiring and assembly while achieving the desired series connection for current reduction.
3Force
If resistive material layers are added to increase resistance, then heat generation increases, but cooling requirements increase
Solution Approach 1:
Insulating layers are introduced as intermediary elements between the electrically-conductive layers. These insulating layers serve as thermal management interfaces, providing electrical isolation while facilitating heat dissipation from the resistive layers to the surrounding cooling structures, thus managing the temperature increase caused by higher resistance operation.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The resistance module effectively increases runup torque and dynamics during the startup phase of electric machines, particularly in high-output applications like synchronous motors, by reducing runup current and promoting efficient cooling and mechanical stability.
Implementation Method 1
the at least two layers are electrically connected to the first connection point and to the second connection point... By coupling the resistance module to the rotor winding... the runup current flowing during the runup phase through the rotor winding can be reduced
Implementation Method 2
a corresponding first insulating layer, which is disposed between two layers in each case... which prevents a short circuit or an undesired lowering of the resistance
Data Source
AI summary
A resistance module for increasing a runup torque for a rotor of an electric machine with a rotor winding includes first and second connection points, a plurality of electrically-conductive layers electrically connected to the first and second connection points. Each of the layers surrounds an axis of the resistance module at least partially in a circumferential direction and has a layer start point and a layer end point. At least one of the layers is configured in an undulating shape in the circumferential direction, with undulations projecting radially outwards. A first insulating layer is disposed between neighboring ones of the layers. The layer end point of one of the layers is electrically connected at a tie point to the layer start point of a neighboring one of the layers. At least one fastening element is disposed between two neighboring undulations in the circumferential direction and radially outside of the layers.