Brushless Motor Stator Segmentation for Power Tool Output
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Solution Overview
Problem
Brushless motors in electric power tools face challenges in achieving higher output without increasing wire diameter, leading to reduced productivity, increased useless space, and potential damage from wire crossover due to vibrations.
Innovation Solution
The electric power tool employs a brushless motor with a stator configuration where coils are wound in three phases, with a specific wire winding method that includes a delta connection, using a cylindrical rotor and a stator core with insulators, where the number of slots per phase is four, series is two, and parallel is two, with terminal wires led out alternately at 60° intervals, reducing wire diameter and minimizing crossover wire intersections.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If a wire with a large diameter is employed to obtain higher output, then the output increases, but productivity decreases and the space factor is reduced
Solution Approach 1:
The patent segments the coil configuration into multiple slots per phase (N slots) with multiple series connections (A series) and parallel connections (B parallel), where N=A×B. This segmentation allows the use of thinner wires while maintaining the required current capacity and output, thereby improving productivity without sacrificing motor performance.
Solution Approach 2:
The patent changes the electrical parameters by adjusting the number of slots, series connections, and parallel connections in the coil configuration. By modifying these parameters according to the relation N=A×B, the system achieves higher output with smaller wire diameters, resolving the contradiction between output and productivity.
2Power
If a wire with a large diameter is employed to obtain higher output, then the output increases, but the space factor is reduced due to increased useless space in the slot
Solution Approach 1:
By segmenting the coil arrangement into multiple smaller coils distributed across N slots per phase, the patent optimizes the utilization of slot space. This segmentation reduces useless space while maintaining the electrical output, as the thinner wires required for segmented coils fit more efficiently into the available slot volume.
Solution Approach 2:
The patent adjusts the parameter N (number of slots per phase) and the connection configuration (A series, B parallel) to optimize space utilization. This parameter optimization ensures that the wire diameter can be reduced without compromising output, thereby improving the space factor.
3Power
If the stator with a large number of slots is used to achieve higher output, then the output increases, but the possibility of damage on insulating coating due to vibrations is increased
Solution Approach 1:
The patent segments the coil configuration into multiple distributed slots, which reduces the concentration of stress and vibration on any single insulating coating. This segmentation distributes the mechanical loads more evenly, reducing the risk of coating damage while maintaining high output capability.
4Power
If the stator with a large number of slots is used to achieve higher output, then the output increases, but downsizing is inhibited due to bulging outward
Solution Approach 1:
By segmenting the coil arrangement into multiple slots with multiple series and parallel connections, the patent reduces the wire diameter required for each coil. This segmentation allows for a more compact stator design without sacrificing output, as the thinner wires reduce the overall volume and prevent bulging outward.
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 configuration decreases resistance in phases, maintains a higher output, and reduces outward bulging, while maintaining a compact design by optimizing the space factor and minimizing the risk of insulating coating damage from vibrations.
Implementation Method 1
a brushless motor that has a high durability compared with a commutator motor and is compact as a driving source
Data Source
AI summary
An electric power tool includes a brushless motor as a driving source. The brushless motor includes a stator and a rotor. The stator includes coils wound around in three phases. In a wire winding method of the coil of the stator, when the number of slots per phase is N, the number of series of the coils per phase is A, and the number of parallel of the coils per phase is B, a relation of N=A×B (note that, N is a natural number of 3 or more and 10 or less, A is a natural number of 1 or more, and B is a natural number of 2 or more) is satisfied.