Real-Time Demagnetized Torque Capability Estimation for Electric Motors
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Solution Overview
Problem
Electric motors in hybrid electric vehicles and other electric-powered devices face performance degradation due to demagnetization over time, affecting torque capability and overall propulsion efficiency.
Innovation Solution
A propulsion system with a controller that determines demagnetized torque capability in real-time by assessing magnet flux linkage, base speed, and available torque contributions, allowing for adaptive control of operating parameters to compensate for demagnetization levels.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If permanent magnets are used in the electric motor to provide torque, then torque capability is improved, but demagnetization occurs over time due to temperature and age, causing performance degradation
Solution Approach 1:
The system performs preliminary detection of magnet flux linkage to identify demagnetization conditions before they cause significant performance loss. By continuously monitoring the flux linkage and comparing it against threshold values, the system can detect demagnetization early and switch to compensatory control strategies proactively
Solution Approach 2:
The system changes control parameters (current commands, voltage limits, torque distribution) based on the detected demagnetization level. When demagnetization is detected, the controller adjusts operating parameters to compensate for the reduced magnet strength, thereby maintaining torque capability despite the degraded magnetic field
2Reliability
If real-time demagnetization detection and compensation is implemented, then performance consistency is improved, but system complexity increases due to additional sensors and control algorithms
Solution Approach 1:
The system uses existing sensor data (current, voltage, speed) to calculate magnet flux linkage through mathematical models rather than requiring additional dedicated sensors. The controller performs self-diagnosis by analyzing the relationship between applied voltages and resulting currents to infer the magnetic field strength, enabling demagnetization detection without external monitoring equipment
Solution Approach 2:
The system implements a feedback loop where the calculated flux linkage is continuously compared against threshold values, and the control parameters are adjusted based on this feedback. When demagnetization is detected, the system feeds back compensation signals to the inverter and controller to maintain optimal performance
3Power
If the electric motor operates at high temperature to improve efficiency, then power output is improved, but demagnetization rate increases due to thermal effects
Solution Approach 1:
The system performs preliminary detection of magnet flux linkage to identify demagnetization conditions before they cause significant performance loss. By continuously monitoring the flux linkage and comparing it against threshold values, the system can detect demagnetization early and switch to compensatory control strategies proactively
Solution Approach 2:
The system changes control parameters (current commands, voltage limits, torque distribution) based on the detected demagnetization level. When demagnetization is detected, the controller adjusts operating parameters to compensate for the reduced magnet strength, thereby maintaining torque capability despite the degraded magnetic field
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 effectively estimates and adjusts torque capability in real-time, optimizing propulsion performance even under demagnetization conditions, ensuring consistent device operation.
Implementation Method 1
determine a magnet flux linkage (λM) of the rotor based in part on the respective signal
Implementation Method 2
The electric motor is configured to selectively provide a first torque contribution to propel the device, and includes a stator and a rotor
Data Source
AI summary
A propulsion system for a device having an electric motor configured to selectively provide a first torque contribution to propel the device. At least one sensor is configured to obtain a respective signal related to the electric motor. A controller is in communication with the sensors and configured to determine a magnet flux linkage (λm) based in part on the respective signal. The controller has a processor and tangible, non-transitory memory on which instructions are recorded for a method of determining a demagnetized torque capability (TD) for the electric motor in real-time. In the event of a threshold level of demagnetization of the electric motor, the method estimates the torque capability in real time of the electric motor, taking the demagnetization level into account. At least one operating parameter of the device is controlled based at least partially on the demagnetized torque capability (TD).