BLDC Stator Circuit Board Interconnections for Higher Power Density
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Solution Overview
Problem
Conventional brushless direct-current (BLDC) motors for rotary tools face challenges in achieving high power density due to limitations in stator winding design and magnetic component layout, resulting in suboptimal torque output and efficiency.
Innovation Solution
The design incorporates a stator assembly with radially extending teeth and a circuit board that facilitates delta or series connections between stator windings, using multiple sets of windings wound in parallel to maximize wire density and reduce electrical resistance, along with a rotor assembly featuring embedded or surface-mount magnets to enhance magnetic flux and power output.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If conventional stator winding design is used, then the motor structure is simple, but the power density and torque output are suboptimal
Solution Approach 1:
The stator windings are divided into multiple sets (first set and second set) wound in parallel on each stator tooth. This segmentation allows optimization of wire density and electrical resistance while maintaining manageable construction complexity through systematic organization of the winding sets.
Solution Approach 2:
The patent introduces a circuit board with conductive traces arranged in delta or series connections, adding a dimensional layer to the winding configuration. This enables complex electrical connections and optimization of power density without significantly increasing mechanical construction complexity.
2Volume of moving object
If motor size is reduced, then compactness is improved, but thermal efficiency and power output may deteriorate
Solution Approach 1:
The patent optimizes electrical parameters including wire density, resistance, and connection configuration (delta or series) to maintain thermal efficiency in compact dimensions. The multiple sets of windings wound in parallel reduce resistance and improve heat dissipation while keeping motor size small.
3Reliability
If wire density is maximized, then electrical resistance is reduced, but manufacturing complexity increases
Solution Approach 1:
The windings are organized into multiple sets that can be wound systematically in parallel on each stator tooth. This segmentation makes the manufacturing process more manageable while achieving high wire density and low electrical resistance through optimized arrangement of the segmented winding sets.
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 achieves a significant increase in power output density, with a motor size constant ratio to electrical envelope of at least 820 N·m/√W per m³, improving torque rating and thermal efficiency while reducing motor size, outperforming conventional BLDC motors in terms of power output and efficiency.
Implementation Method 1
a stator assembly including a stator having a stator core and stator teeth radially extending from the stator core and defining slots therebetween, and stator windings wound on the stator teeth
Implementation Method 2
a rotor assembly including rotor shaft extending along a longitudinal axis and a rotor supporting magnets mounted on the rotor shaft
Data Source
AI summary
A brushless direct-current (BLDC) motor for a power tool includes a rotor assembly; a stator assembly including a stator having stator teeth forming slots therebetween and stator windings wound around the stator teeth; stator terminals extending substantially parallel to the longitudinal axis from the stator assembly and being substantially aligned with centerlines of the slots of the stator assembly; and a circuit board mounted on the stator terminals adjacent the stator assembly. The circuit board includes conductive traces facilitating a one of a delta or a series connection between the stator windings. An end insulator is provided at an axial end of the stator to electrically insulate the stator from the stator windings, the end insulator including support members to support the stator terminals relative to the stator assembly. The circuit board is mounted and fastened to the support members.