Electric Motor Busbar Ground Contact for EMI Reduction
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Solution Overview
Problem
Brushless DC motors generate disruptive electromagnetic radiation, which affects electromagnetic compatibility, particularly in vehicle installations, and conventional metallic housings are not effective in suppressing interference at higher power levels.
Innovation Solution
An electric motor design that includes a ground contact system with a busbar holder and overmolded ground contact, integrated into the stator core, providing a reliable and low-resistance connection to ground potential, reducing electromagnetic radiation by effectively grounding the stator.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If metallic housings are used for shielding, then electromagnetic radiation suppression is improved, but the possibility of electrically contacting capacitors to the motor housing is eliminated when the housing is electrically non-conductive
Solution Approach 1:
The housing is segmented into a non-conductive main housing body and a separate conductive grounding component (busbar holder with ground contact). This allows the housing to maintain its non-conductive properties for shielding while providing a dedicated conductive path for electrical grounding of capacitors, resolving the contradiction between shielding effectiveness and electrical connection capability.
Solution Approach 2:
A conductive busbar holder with ground contact serves as an intermediary element between the non-conductive housing and the electrical grounding system. This mediator provides the necessary electrical connection capability without requiring the entire housing to be conductive, thus maintaining both shielding effectiveness and electrical connection versatility.
2Ease of operation
If a ground contact system is integrated into the stator core, then assembly is simplified and reliability is improved, but manufacturing complexity increases
Solution Approach 1:
The ground contact system is merged with the busbar holder, which is already integrated into the stator core. By combining the grounding function with the existing busbar holder structure, the patent achieves simplified assembly (fewer separate components) while managing manufacturing complexity through integrated design of the conductive elements within the insulating holder.
3Power
If busbars are used for winding connections, then power handling capability is improved, but electromagnetic radiation increases
Solution Approach 1:
The busbar holder with ground contact acts as an intermediary that provides a controlled electrical path for high-power connections. By establishing a reliable ground reference through the ground contact, the system can handle higher power levels while the structured grounding helps control electromagnetic radiation by providing a defined return path for currents.
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 significantly minimizes electromagnetic radiation, enhancing electromagnetic compatibility and simplifying assembly by ensuring a secure and low-resistance ground connection for the stator, thereby reducing interference in motor vehicle installations.
Implementation Method 1
the ground contact establishes a connection with the stator in a simple and reliable manner
Data Source
AI summary
An electric motor includes a rotor rotatable about a rotation axis, and a stator that externally surrounds the rotor and includes a stator core and coils wound on the stator core. The windings are defined by a winding wire including winding wire end portions that are electrically contacted at end surfaces thereof by busbars held at least partially in a busbar holder, and include a ground contact to connect the stator to a ground potential. The ground contact includes a first end region received in a longitudinal groove on an outside of the stator core.