Stator Coil Star-Point Layout to Suppress Circulating Currents
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Solution Overview
Problem
The design of stator coil strings with bundles of conductors in rotary induction motors leads to additional electrical losses due to voltage differences and circular currents caused by conventional short-circuiting at a common star point.
Innovation Solution
The conductors of different stator coil strings are electrically connected via multiple independently provided star points, which are electrically decoupled from each other, forming a star-delta circuit to minimize voltage differences and suppress circulating currents.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If conductors of bundles are short-circuited at a common star point, then the star inductors can be electrically connected, but circular currents occur causing additional electrical losses
Solution Approach 1:
The patent divides the single common star point into multiple separate star points (first star point, second star point, third star point). Each star point connects a specific subset of conductors from different stator coil strings, segmenting the electrical connection path. This segmentation prevents circular currents by eliminating the closed loop that would form with a single common connection point, while still achieving the necessary electrical connectivity for all star inductors.
2Loss of energy
If multiple star points are provided to suppress circulating currents, then electrical losses are reduced, but the device complexity increases
Solution Approach 1:
Each star point is assigned a specific local function: the first star point connects conductors from first and second stator coil strings, the second star point connects conductors from second and third stator coil strings, and the third star point connects conductors from third and first stator coil strings. This localized functional assignment optimizes the connection topology to eliminate circular currents while maintaining manageable complexity through systematic distribution of connection responsibilities.
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
This design significantly reduces electrical losses by statistically compensating voltage differences and preventing circular currents, enhancing the efficiency of the stator coil arrangement.
Implementation Method 1
The stator coil strings can be connected to a rotary supply voltage at respective phase connections in order to generate a rotary magnetic field
Data Source
AI summary
A stator for a rotary induction motor with a stator main body, the stator being assigned a geometric machine axis, the stator having stator slots and a stator coil arrangement with a plurality of stator coil strands, which can be connected to a rotary supply voltage at respective phase terminals in order to generate a rotary magnetic field, the stator coil strings each having a bundle with a plurality of conductors, the conductors of a bundle being arranged together to form respective star inductors in the stator slots, and the conductors each having a phase-connection-side portion and a star-point-side portion, the conductors of a bundle being electrically connected to the phase connection of the respective stator coil string via the phase-connection-side portion. The conductors of bundles of different stator coil strings are electrically connected to one another via the star-point-side portion by means of respective star points.