BLDC Motor Winding Layout for Compact High-Power Tools
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Solution Overview
Problem
Existing brushless motor assemblies for rotary tools face challenges in achieving high power density within a compact size, limiting their maximum power output and efficiency compared to conventional designs.
Innovation Solution
The design incorporates a brushless direct-current (BLDC) motor with a rotor assembly and stator assembly, featuring a unique configuration of stator windings wound in parallel on each tooth, a circuit board for connecting the windings in delta or series configurations, and a power module for efficient power management, optimizing the magnetic and electrical envelopes to enhance power density.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If conventional BLDC motor designs are used, then the motor structure is simple and easy to manufacture, but the power density and maximum power output are limited
Solution Approach 1:
The motor is divided into distinct functional modules: rotor assembly with magnets, stator assembly with windings, circuit board for electrical connections, and housing. This segmentation allows each component to be optimized independently for performance while maintaining manufacturability.
Solution Approach 2:
The patent optimizes the motor constant Km by enhancing the magnetic and electrical envelopes in three-dimensional space. The stator windings are configured with specific radial and axial dimensions, and the rotor magnets are positioned to maximize the magnetic envelope, achieving high power density through spatial optimization.
2Power
If the motor size is reduced for compact tools, then the tool portability is improved, but the maximum power output is limited
Solution Approach 1:
The patent achieves high power output in a compact size by optimizing critical parameters: the motor constant Km is enhanced through improved magnetic envelope (rotor magnet configuration) and electrical envelope (stator winding arrangement). The ratio of inner diameter to outer diameter of the stator is optimized to 0.5-0.53, and the axial length is minimized while maintaining performance.
Solution Approach 2:
The motor uses composite construction combining permanent magnets in the rotor with laminated stator core and copper windings. This composite approach maximizes the magnetic field strength and electrical efficiency within the constrained volume, achieving superior power density.
3Power
If high power density is achieved through optimized magnetic and electrical envelopes, then the power output is improved, but the manufacturing precision requirements increase
Solution Approach 1:
The patent applies local quality optimization by configuring the rotor magnets and stator windings with specific local geometries and positions. The magnetic envelope is optimized through precise magnet placement on the rotor, and the electrical envelope is optimized through specific winding arrangements on the stator teeth, achieving high power density through localized precision rather than uniform complexity throughout.
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 results in a motor with a maximum power output of at least 1840 watts and improved power density, exceeding conventional BLDC motors in terms of motor constant and efficiency, while maintaining a compact size.
Implementation Method 1
a brushless direct-current (BLDC) motor with a rotor assembly and stator assembly, featuring a unique configuration of stator windings wound in parallel on each tooth
Implementation Method 2
The design incorporates a brushless direct-current (BLDC) motor with a rotor assembly including rotor shaft extending along a longitudinal axis and a rotor supporting magnets mounted on the rotor shaft; and a stator assembly including a stator comprising a stator core and stator teeth radially extending from the stator core and defining slots therebetween, and stator windings wound on the stator teeth
Data Source
AI summary
A brushless direct-current (BLDC) motor for a power tool includes a rotor assembly and a stator assembly including stator windings. A ratio of a motor size (Km) constant of the motor to an electrical envelope of the motor including electrical parts of the motor is greater than approximately 850 (N.m/√W)/m{circumflex over ( )}3. A ratio of a motor size (Km) constant of the motor to a magnetic envelope of the motor including stator core and windings is greater than approximately 980 (N.m/√W)/m{circumflex over ( )}3.