Double-Tooth Coil Winding for Low-Pole Induction Machines
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Solution Overview
Problem
Toothed coil windings in induction machines with low numbers of poles (e.g., 2-pole or 4-pole) face challenges in high-speed drives due to disruptive wide air gap field spectra, which hinder the start-up of line start motors and limit their implementation in high-speed applications, and they tend to have higher pole pairs, making them less effective for small pole numbers.
Innovation Solution
A double tooth coil winding (DOZA) with a specific winding scheme is used, where each double tooth coil occupies half of four adjacent slots, comprising two concentric coils with the outer coil wound around the inner coil, and the current direction is reversed in offset coils, allowing for efficient winding with a favorable field spectrum and reduced upper field amplitudes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If toothed coil windings are used in induction machines with low numbers of poles, then the machine structure is simplified and manufacturing is easier, but the air gap field spectrum becomes wide and disruptive, preventing line start functionality
Solution Approach 1:
The winding is divided into multiple layers with different coil configurations. Each layer has coils with different numbers of turns, creating a segmented structure that allows independent optimization of each layer's contribution to the field spectrum, thereby eliminating disruptive harmonics while maintaining manufacturing simplicity
Solution Approach 2:
Different regions of the winding (different layers and slots) are assigned different local properties, specifically different numbers of turns per coil. This local differentiation allows the winding to produce a tailored field spectrum that suppresses harmful harmonics in specific frequency ranges while maintaining the overall toothed coil structure
2Device complexity
If conventional toothed coil windings are used, then the winding structure is simple, but upper field amplitudes are high, reducing field utilization efficiency
Solution Approach 1:
The winding design incorporates dynamic adjustment of turn ratios between inner and outer coils. By optimizing the turns ratio dynamically during the design process, the winding achieves minimal upper field amplitudes while maintaining structural simplicity, thereby improving field utilization without significantly increasing complexity
Solution Approach 2:
The invention changes key parameters of the toothed coil winding, specifically the number of turns in different layers and the pole pair number. By adjusting these parameters, the winding achieves a favorable field spectrum with reduced upper field amplitudes while keeping the overall structure simple and easy to manufacture
3Strength
If toothed coil windings with higher pole pairs are used, then the winding structure is more robust, but the machine is less effective for small pole numbers and high-speed drives
Solution Approach 1:
The multi-layer toothed coil winding design creates a universal solution that can be effectively applied across different pole numbers, including low-pole configurations (2-pole and 4-pole). The winding structure maintains its robustness while adapting to various pole numbers through parameter optimization, enabling use in both high-speed drives and line start applications
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 double tooth coil winding achieves improved field utilization and selectivity, increasing the basic field amplitude while reducing upper field amplitudes, enabling effective operation in low-pole machines with enhanced cost-effectiveness and modular design.
Implementation Method 1
A double tooth coil winding (DOZA) with a specific winding scheme is used, where each double tooth coil occupies half of four adjacent slots, comprising two concentric coils with the outer coil wound around the inner coil
Data Source
Figure 1~3
Figure 4~6
AI summary
The invention relates to a three-phase machine having a 2-pole stator (10) formed with a winding arrangement of a double toothed coil winding comprising m winding phases, wherein the winding arrangement consists of at least one first double toothed coil (20) and a second double toothed coil, which each fill half of four adjacent grooves (N) of the stator (10) with a winding phase (W), wherein each double toothed coil (20) forms two concentrically arranged coils and the second double toothed coil is arranged in a manner offset by a pole pitch with respect to the first double toothed coil (20).