Scooter Motor Stator Winding Temperature Sensing for Overheat Protection
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Solution Overview
Problem
Existing electric scooter motors face challenges with temperature drift and inconsistency in mass production, leading to unreliable overheating protection, which results in safety hazards and high after-sales costs due to the limitations of NTC thermistors in detecting temperature changes accurately.
Innovation Solution
The solution involves placing a mechanical temperature sensor, such as a bimetallic contact type mechanical switch, in close vicinity to the stator winding, often via a thermal conductive material, to provide real-time temperature monitoring and prevent overheating by sending signals to the motor controller to limit or stop the motor's power, ensuring reliable and stable temperature detection without software or hardware interference.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If an NTC thermistor is used for temperature sensing, then the motor can have overheat protection function, but the temperature drift is large and consistency of mass production is difficult to control
Solution Approach 1:
The patent replaces the electronic NTC thermistor-based temperature sensing system with a mechanical temperature sensor system. The mechanical sensor directly converts temperature changes into mechanical displacement or contact state changes, eliminating the need for ADC circuits and software processing. This substitution resolves the contradiction by providing reliable overheat protection through mechanical means that are inherently more consistent in mass production and less prone to temperature drift.
Solution Approach 2:
The mechanical temperature sensor utilizes the thermal expansion or phase change properties of materials to automatically detect temperature changes and trigger protection mechanisms without requiring external power supply or complex signal processing circuits. The sensor itself performs the detection and triggering functions, reducing system complexity and improving reliability in mass production.
2Reliability
If NTC thermistor with ADC circuit is used for temperature protection, then overheat protection can be achieved, but the protection function is prone to failure causing after-sales complaints
Solution Approach 1:
The patent replaces the complex electronic control system (NTC thermistor + ADC circuit + software processing) with a simple mechanical temperature sensor system. The mechanical sensor directly triggers protection actions through mechanical contact or displacement, eliminating multiple electronic components and reducing points of failure. This significantly improves protection function reliability while reducing device complexity.
Solution Approach 2:
The patent extracts and removes the complex ADC circuit and software processing requirements from the temperature protection system, retaining only the essential temperature detection and triggering functions through a mechanical sensor. This extraction simplifies the overall system architecture and reduces the complexity of control circuits while maintaining effective overheat protection.
3Measurement precision
If temperature sensor is located away from stator winding, then the sensor is easier to install, but the temperature detection is not real-time and accurate
Solution Approach 1:
The patent segments the temperature sensor into a separate modular component that can be independently positioned and installed on the stator winding surface. This segmentation allows the sensor to be placed in optimal thermal contact positions without complicating the overall manufacturing process, achieving both accurate real-time temperature detection and ease of installation.
Solution Approach 2:
The patent introduces a thermal conductive material as an intermediary between the mechanical temperature sensor and the stator winding. This intermediary ensures efficient heat transfer from the winding to the sensor while allowing for easy installation and positioning. The thermal conductive material compensates for any small gaps or surface irregularities, maintaining both detection accuracy and installation simplicity.
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 approach enhances the reliability and consistency of temperature protection, reducing the risk of motor damage and after-sales complaints by providing precise and stable temperature monitoring, independent of ADC circuit issues, and allowing for stepwise power reduction or motor shutdown to prevent overheating.
Implementation Method 1
the at least one temperature sensor is bonded to the stator winding via a thermal conductive material, particularly silicone grease. This conductive material has a thermal conductivity coefficient ≥ 3 and is thus adapted to provide a very good temperature conduction between the stator winding and the temperature sensor.
Implementation Method 2
the mechanical temperature sensor is a bimetallic contact type mechanical switch. When the bimetallic temperature sensor detects overheating of the stator winding, it sends an open circuit signal (normally closed) or a short circuit signal (normally open) to the motor controller.
Data Source
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AI summary
The present invention relates to an electric scooter motor (40) comprising a stator (50) and a rotor (62), the stator (50) of the scooter motor comprising a stator winding (54). The scooter motor (40) comprises at least one temperature sensor (60) configured to output a temperature signal to a motor controller of an electric scooter (10). According to the invention the at least one temperature sensor (60) is located in connection with the stator winding (54) which allows an effective protection of the scooter motor (40).