Split-Core Stator Bus Bar Structure for Cooling and Short Prevention

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Solution Overview

Problem

Existing brushless electric motors for aircraft and drones face issues with overheating, moisture ingress leading to electrical shorts and fires, and inefficient cooling of stators, particularly in high-power applications, which affect efficiency and lifespan.

Innovation Solution

A stator design using a split core structure with insulating heat dissipation composite material, integrated through insert molding, and a three-phase coil winding method, combined with inner and outer air cooling, to enhance heat dissipation and insulation, and a bus bar structure for improved assembly and circuit stability.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Temperature

If cooling holes are provided in the case to dissipate heat from the stator, then heat dissipation is improved, but foreign substances such as rainwater, moisture, or dust may enter the case causing electrical short circuits

Engineering Contradiction:

Improveheat dissipationVSAvoidelectrical short circuit prevention

Core Design Contradiction:

TemperatureVSReliability

Solution Approach 1:

A cover member is introduced as an intermediary component between the cooling holes and the stator. This cover member includes through holes that allow air flow for cooling while preventing foreign substances from directly contacting the stator, thus mediating between the conflicting requirements of heat dissipation and protection

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The cooling system is segmented into multiple components: the case with cooling holes, the cover member with through holes, and the stator. This segmentation allows each component to perform its specific function - the case provides structural support and initial cooling, the cover member filters and directs airflow, and the stator generates heat that needs dissipation

Inventive Principle:

Principle #1Segmentation

2Reliability

If a tarp such as vinyl is used to cover the electric motor to prevent moisture entry, then protection against foreign substances is improved, but the solution becomes temporary and cumbersome

Engineering Contradiction:

Improvemoisture protectionVSAvoidcovering structure

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The protective function previously requiring an external tarp is merged into the motor's own structure through the cover member. The cover member is an integral part of the motor assembly that combines protection and cooling functions, eliminating the need for separate protective coverings

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The motor structure itself provides protection against moisture and foreign substances through its own cover member, rather than requiring external protective measures. The design is self-sufficient, with the cover member being part of the motor assembly that automatically protects the stator

Inventive Principle:

Principle #25Self-service

3Power

If the case rotates at constant speed during operation, then propulsion efficiency is improved, but rain and moisture are less likely to enter while the motor runs, yet foreign substances can enter when the aircraft is stopped

Engineering Contradiction:

Improvepropulsion efficiencyVSAvoidforeign substance intrusion

Core Design Contradiction:

PowerVSObject-affected harmful factors

Solution Approach 1:

The cover member is pre-installed and positioned to cover the stator before the motor operates or stops. This preliminary protective measure ensures that regardless of whether the motor is running or stopped, the stator is already protected from foreign substances, eliminating the vulnerability during stationary periods

Inventive Principle:

Principle #10Preliminary action

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 solution effectively prevents electrical shorts, enhances cooling efficiency, increases assembly productivity, and improves motor durability by minimizing coil resistance and maintaining circuit stability under high-temperature conditions.

Implementation Method 1

assembling a bus bar and a bus bar bracket, and connecting both ends of the coil to the bus bar to form a secondary temporary assembly

Methodology Applied

Scientific EffectThermal conduction: Conduction (thermal)

Implementation Method 2

U-phase, W-phase, and V-phase bus bars, each inserted and fixed to one of the four guide channels, in which a plurality of connection terminals to which start terminals of each core group are connected

Methodology Applied

Scientific EffectElectrical conduction: Conduction (electrical)

Data Source

PatentUS12620841B2Stator having bus bar structure, propeller driving motor using same, and method for manufacturing stator

Publication Date: 2026.05.05 AMOTECH CO LTD

AI summary

A stator having a bus bar structure that enhances assembly productivity and durability by adopting the bus bar structure comprises: a division type stator core in which a plurality of split cores are assembled in an annular shape; upper and lower insulators surrounding the outer circumference of teeth of the split cores; a stator coil composed of a plurality of core groups continuously wound onto three teeth for each phase; a plurality of bus bar brackets coupled to the insulators so as to bind two split cores; U-phase, W-phase, and V-phase bus bars on which a connection terminal to which a start terminal of each core group is connected is protruded; a common electrode bus bar on which a connection terminal to which an end terminal of each core group is connected is protruded; and a stator support that insulates between coils so as to integrate the plurality of split cores.