Switching Element Heat Stress Estimation in Motor Controllers
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Solution Overview
Problem
Existing motor controllers do not accurately account for the difference in heat stress experienced by switching elements during temperature rise and fall phases, leading to inadequate cooling and potential damage due to thermal expansion and contraction.
Innovation Solution
A motor controller system that includes a temperature sensor and computer to calculate temperature differences between adjacent maximum and minimum points in the time-dependent temperature change of switching elements, allowing for accurate estimation of heat stress and adaptive cooling control.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If the switching element operates with large current to provide high output power, then the power output is improved, but the heating value and temperature of the switching element increase
Solution Approach 1:
The patent applies parameter changes by dynamically adjusting the switching element's operating parameters (current, voltage, duty cycle) based on real-time temperature monitoring. When temperature exceeds thresholds, the control device modifies electrical parameters to reduce power dissipation and cooling requirements, thereby maintaining power output within safe thermal limits
2Adaptability or versatility
If the switching element frequently experiences temperature changes due to repeated start-stop and acceleration-deceleration, then the adaptability to varying operating conditions is improved, but the heat stress and thermal expansion-contraction damage increase
Solution Approach 1:
The patent implements preliminary action by establishing predetermined temperature thresholds and preparing cooling strategies in advance. The control device monitors temperature trends and preemptively activates cooling measures before excessive thermal stress accumulates, preventing damage from repeated thermal cycling while maintaining operational adaptability
Solution Approach 2:
The patent employs feedback mechanisms by continuously monitoring switching element temperature and using this information to adjust operating parameters and cooling control in real-time. The temperature data feeds back to the control device, which modifies power delivery and cooling activation to minimize thermal stress while preserving the ability to adapt to varying load conditions
3Device complexity
If conventional cooling control is used without differentiating between temperature rise and fall phases, then the device complexity is reduced, but the measurement precision of heat stress estimation deteriorates
Solution Approach 1:
The patent applies segmentation by dividing the temperature change process into distinct phases (temperature rise phase and temperature fall phase) and applying different evaluation criteria and control strategies to each phase. This segmentation enables precise heat stress estimation by capturing the asymmetry in thermal expansion-contraction damage, while the control device manages the increased complexity through automated phase detection and threshold-based control logic
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 system provides accurate estimation of heat stress, enabling enhanced cooling and reducing damage to switching elements by differentiating between temperature rise and fall phases, thus improving the reliability of motor controllers in electric vehicles and robots.
Implementation Method 1
a switching element that converts output electric power of an electric power supply into motor-driving electric power
Implementation Method 2
a temperature sensor to measure a temperature of the switching element
Implementation Method 3
the temperature of the switching element frequently changes. Due to the change in the temperature of the switching element, the switching element (or components around the switching element) repeats expansion and contraction
Data Source
AI summary
The specification is related to a motor controller, a vehicle including the motor controller and a heat stress estimating method for a switching element. The motor controller includes a switching element, a temperature sensor, and a computer. The switching element is configured to convert output electric power of an electric power supply into motor-driving electric power. The temperature sensor is configured to measure a temperature of the switching element. The computer is configured to extract a maximum point and a minimum point in a time-dependent change in the temperature of the switching element, the computer is configured to calculate a temperature difference between the maximum point and the minimum point adjacent to each other and configured to calculate an estimated value of a heat stress to which the switching element is subjected based on each calculated temperature difference.