Derating Electric Drive Motor Torque via Temperature Feedback
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Solution Overview
Problem
Heavy machinery, such as off-highway trucks, face significant downtime and maintenance challenges due to electrical component overheating in direct series electric drive systems, leading to substantial monetary losses and the need for skilled personnel to troubleshoot and repair malfunctions.
Innovation Solution
An electronic controller is configured to receive temperature and motor speed signals, calculating a deration value using a derating scheme that considers current operating state parameters, thereby reducing the risk of thermal damage by adjusting torque limits and power output in response to overheating conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the electrical motor operates at high power output, then productivity is improved, but thermal damage risk increases
Solution Approach 1:
The patent implements dynamic derating of the electrical motor by continuously monitoring temperature signals and adjusting the torque limit in real-time based on thermal conditions. The electronic controller modifies operational parameters dynamically, reducing torque limits when temperature thresholds are exceeded, thereby preventing thermal damage while maximizing power output during normal operating conditions.
Solution Approach 2:
The system changes operational parameters (torque limit, power output) based on temperature conditions. When temperature exceeds predetermined thresholds, the controller adjusts these parameters to reduce thermal loading on the motor, allowing high power output during safe temperature ranges while preventing thermal damage through parameter modification when limits are approached.
2Reliability
If traditional temperature-based protection is used, then thermal damage is prevented, but downtime increases due to shutdowns
Solution Approach 1:
Instead of completely shutting down the motor when temperature thresholds are exceeded, the system applies partial action by derating the torque limit to a reduced but non-zero value. This allows the motor to continue operating at reduced capacity, preventing total shutdown and minimizing downtime while still providing thermal protection. The motor operates in a derated state rather than being completely stopped.
Solution Approach 2:
The electronic controller continuously monitors temperature signals and provides feedback to adjust the torque limit accordingly. When temperature exceeds thresholds, the controller reduces torque limits and maintains this derated operation until thermal conditions improve, allowing the system to recover and continue operation rather than requiring complete shutdown and manual intervention.
3Reliability
If torque limit is reduced for derating, then thermal damage is prevented, but productivity decreases
Solution Approach 1:
The system dynamically adjusts torque limits based on real-time temperature conditions rather than applying static reduction. During normal thermal conditions, the motor operates at full torque capacity, maximizing productivity. When temperature approaches dangerous levels, the torque limit is reduced only to the extent necessary to prevent thermal damage, allowing the system to maintain high productivity during safe operation while providing thermal protection when needed.
Data Source
AI summary
A machine propelled by an electric motor and subject to a deration scheme is described wherein deration is specified by a combination of a temperature signal indicating a degree to which a machine component is overheating. The machine includes an electronic controller that receives a temperature signal indicative of a current temperature status of the electric motor. The electronic controller receives a motor speed signal indicative of a current speed status of the electric motor. The electronic controller calculates, in accordance with a derating scheme, a deration value for the electric motor, the deration value being determined by applying a set of current operating state parameter values to the derating scheme. The set of current operating state parameters include: a motor speed parameter value; and a temperature parameter value.