EC Motor Stator Indirect Temperature Monitoring via Molded Encapsulation
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Solution Overview
Problem
The complex manufacturing and assembly process of brushless electric motors due to the need for multiple thermal protectors or sensors on the stator windings, which increases costs and complexity.
Innovation Solution
A stator design where the stator core and windings are fully enclosed in a molded plastic encapsulation with a temperature sensor outside, allowing the control electronics to calculate winding temperatures using a stored temperature profile, eliminating the need for complex sensor assembly and enabling indirect thermal contact through a conductive medium.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If multiple thermal protectors or sensors are placed directly on the stator windings, then temperature protection reliability is improved, but device complexity and manufacturing cost increase
Solution Approach 1:
The temperature sensor is extracted from the stator windings and placed on the stator housing instead. This single external sensor position replaces multiple sensors that would need to be mounted directly on the windings, significantly simplifying the assembly process while maintaining temperature monitoring capability through the housing's thermal properties
Solution Approach 2:
The stator housing is given a dual function: it serves both as the structural enclosure for the motor components and as the thermal sensing element. By incorporating the temperature sensor on the housing and using the housing's thermal conductivity, the system achieves both mechanical protection and temperature monitoring with a single component
2Reliability
If multiple thermal protectors or sensors are placed directly on the stator windings, then temperature protection reliability is improved, but manufacturing cost increases
Solution Approach 1:
The temperature sensor is extracted from the stator windings and placed on the stator housing instead. This single external sensor position replaces multiple sensors that would need to be mounted directly on the windings, significantly simplifying the assembly process while maintaining temperature monitoring capability through the housing's thermal properties
Solution Approach 2:
The invention uses the stator housing as a thermal copy or proxy for the stator windings. Instead of directly measuring winding temperature, the system measures housing temperature which correlates to winding temperature through thermal conduction, providing an indirect but effective temperature monitoring solution
3Ease of manufacture
If a temperature sensor is placed outside the encapsulation, then manufacturing process is simplified, but temperature detection precision may be reduced
Solution Approach 1:
The stator housing acts as a thermal intermediary between the stator windings and the temperature sensor. The housing's defined thermal conductivity enables it to transfer thermal information from the windings to the external sensor, allowing accurate temperature detection without direct sensor contact with the windings
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
Simplifies the manufacturing process, reduces costs, and effectively protects the motor from excessive temperature by accurately determining winding temperatures and turning off the current when necessary, with an accessory electronic error control for detection inertia.
Implementation Method 1
a molded encapsulation made of a plastic material of a defined, known thermal conductivity
Data Source
AI summary
A stator for a brushless, electronically commutated electric motor having a stator core wound with stator windings and control electronics for controlling the stator windings. The stator core together with the stator windings are enclosed in a molded encapsulation made of a plastic material of a defined thermal conductivity (λSt). The temperature sensor is arranged on the outside at the encapsulation, and the control electronics are designed such that they calculate the temperature in the region of the stator windings on the basis of the temperature detected by the temperature sensor taking into account a specific stator temperature profile stored in a memory. Furthermore, the invention relates to a brushless, electronically commutated electric motor having a stator as described above.