Thermal Model Current Limiter for Electric Motor Overheating
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Direct measurement of coil temperature in electric motors is not always feasible due to added cost and complexity, making it challenging to implement temperature-based current limiting to prevent overheating.
Innovation Solution
A thermal model is used to estimate coil temperature in electric motors, allowing for real-time current limiting without direct temperature measurement, using instantaneous power consumption and thermocouple data from the motor's printed circuit board, which calculates a 'power limit' and 'maneuver budget' to prevent overheating.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If direct temperature measurement is implemented, then current limiting protection is achieved, but cost and complexity increase
Solution Approach 1:
The patent introduces a thermal model as an intermediary that estimates coil temperature based on electrical parameters (current, voltage, power consumption) and a single PCB temperature sensor reading. This model acts as a mediator between the easily measurable electrical parameters and the difficult-to-measure coil temperature, enabling current limiting protection without direct coil temperature sensors.
Solution Approach 2:
The patent replaces the physical direct measurement approach (mechanical/physical temperature sensors on coils) with a computational thermal model that uses electrical measurements and a single temperature sensor to estimate coil temperature. This substitution eliminates the need for complex direct temperature measurement hardware while achieving the same protective function.
2Measurement precision
If multiple temperature sensors are used, then measurement precision is improved, but device complexity and cost increase
Solution Approach 1:
The patent segments the temperature measurement function into two parts: (1) a single temperature sensor measures the PCB temperature, and (2) a thermal model estimates the coil temperature based on this measurement plus electrical parameters. This segmentation allows the system to achieve coil temperature monitoring capability without placing sensors directly on the coils, reducing hardware complexity while maintaining measurement precision through computational estimation.
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 solution enables safe operation of electric motors without direct temperature measurement, reducing cost and complexity while preventing overheating during demanding maneuvers, such as climbing hills.
Implementation Method 1
a temperature-based current limiter can be used to protect the motor... direct measurement of the coil temperature is not always feasible
Implementation Method 2
using instantaneous power consumption and thermocouple measurement from inside of the motor
Data Source
AI summary
A current limiter for protecting a motor from overheating. An algorithm is disclosed for dynamically limiting the motor current, such as motors used in robotics. The algorithm uses a thermal model of the motor, which provides a real-time estimate of a coil temperature using instantaneous power consumption of the motor and a thermocouple measurement from the motor's printed circuit board. There are multiple potential outputs from the current limiter algorithm, such as the maximum power that can be consumed without overheating the coils, and an estimate of how long the motor could deliver a specified high torque before overheating.