Motor Temperature Estimation Using Thermal Node Model
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Solution Overview
Problem
Existing methods fail to accurately estimate motor temperature in real-time, especially in hybrid or battery-powered vehicles, due to the complexity of heat transfer within electric motors and the lack of effective thermal modeling.
Innovation Solution
A thermal model is used, comprising nodes representing motor regions and thermal resistances representing heat transfer paths, which is solved by a computing device to determine temperature changes and estimate motor temperature in real-time, considering energy balance equations and operating conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a thermal model with multiple nodes and thermal resistances is implemented, then temperature estimation accuracy is improved, but computational complexity increases
Solution Approach 1:
The motor is divided into multiple thermal nodes (stator winding, stator core, rotor winding, rotor core, bearing, housing) that represent different physical regions. Each node has its own temperature equation, allowing the system to capture spatial temperature variations throughout the motor structure, thereby improving estimation accuracy while keeping each individual node calculation simple.
Solution Approach 2:
Thermal resistances are introduced as intermediary parameters between thermal nodes to model heat transfer paths. These thermal resistances act as mediators that simplify the complex heat transfer physics into manageable algebraic relationships, enabling accurate temperature estimation without requiring complex differential equations for each heat transfer path.
2Productivity
If real-time temperature estimation is achieved through thermal modeling, then thermal management efficiency is improved, but computational resources required increase
Solution Approach 1:
The thermal model uses readily available operating parameters (current, speed, torque) that are already measured for motor control purposes. By leveraging these existing measurements, the system performs temperature estimation without requiring additional sensors or dedicated measurement infrastructure, thus improving thermal management efficiency while minimizing additional computational energy consumption.
Solution Approach 2:
The model transforms complex thermal field problems into a set of algebraic equations by assuming steady-state conditions and using equivalent thermal circuit representations. This parameter transformation allows real-time calculation using standard microcontroller capabilities, achieving both real-time performance and energy efficiency.
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 allows for accurate and real-time estimation of motor temperature, accounting for heat generation and transfer, thereby improving thermal management and efficiency in electric vehicles.
Implementation Method 1
The thermal model includes a plurality of nodes and at least one thermal resistance. Each node represents a region of the motor and each thermal resistance represents a heat transfer path between at least two of the nodes.
Implementation Method 2
solving, via a computing device, an energy balance equation for each node in the thermal model to determine a temperature change at each node
Data Source
AI summary
A vehicle includes a power source, a motor, and a computing device. The power source provides electrical energy to the motor, and the motor generates rotational motion from the electrical energy received. The computing device is configured to estimate a temperature of the motor in real time based at least in part on a thermal model of the motor. The thermal model includes a plurality of nodes and at least one thermal resistance. Each node represents a region of the motor and each thermal resistance represents a heat transfer path between at least two of the nodes. A method includes solving one or more energy balance equations to determine a temperature change at each node and estimating the temperature of the motor in real time based at least in part on the temperature change at each node and at least one of the thermal resistances in the thermal model.