Electric Motor Torque Control Using Power-Based Map Correction
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Solution Overview
Problem
Existing electric motor management systems in hybrid vehicles face inaccuracies in estimating maximum torque due to manufacturing variations and drifts over time, leading to inefficient use of both electric and combustion engines, and potential battery damage.
Innovation Solution
A method involving a correction data table and real-time updating mechanism, which calculates torque based on electrical power, rotational speed, and voltage, without the need for a torque measurement sensor, to optimize motor and battery performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If manufacturer maps are used to estimate maximum torque, then torque estimation is simplified, but accuracy deteriorates due to manufacturing variations and drifts over time
Solution Approach 1:
The system uses feedback from the motor controller about actual motor performance to continuously update and refine the torque estimation. The correction data table stores deviation values that are applied to manufacturer maps based on actual measured performance, creating a closed-loop system that improves accuracy while maintaining simplicity.
Solution Approach 2:
Instead of using expensive torque measurement sensors, the system creates a corrected copy of the manufacturer's torque map by storing correction factors in a data table. This copied and corrected map accurately reflects actual motor performance without requiring direct torque measurement hardware.
2Measurement precision
If torque measurement sensors are added to improve accuracy, then torque estimation precision improves, but device complexity and cost increase
Solution Approach 1:
The system creates a virtual torque measurement by copying and correcting manufacturer map data based on electrical measurements and performance feedback, eliminating the need for physical torque sensors while achieving accurate torque estimation.
Solution Approach 2:
The system replaces mechanical torque measurement sensors with an electrical-based estimation method using current measurements, voltage measurements, and corrected manufacturer maps, eliminating mechanical components while maintaining measurement accuracy.
3Device complexity
If manufacturer maps are used without correction, then system simplicity is maintained, but torque estimation accuracy deteriorates due to individual motor variations
Solution Approach 1:
The system incorporates feedback from actual motor performance measurements to update correction factors in the data table, allowing the system to adapt to individual motor characteristics and manufacturing variations while maintaining overall system simplicity.
Solution Approach 2:
The system changes the parameters used for torque estimation by incorporating correction factors based on electrical measurements and performance data, allowing accurate torque estimation that accounts for individual motor variations without complicating the overall system architecture.
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 precise torque management, enhancing the efficiency and longevity of electric motors in hybrid vehicles, reducing CO2 emissions by optimizing the use of both engines without additional sensor costs.
Implementation Method 1
an electric motor is supplied with electric current by a battery and transforms the electrical energy 'stored' in the battery into mechanical torque transmitted to the wheels of the vehicle
Implementation Method 2
the electric motor also functions as a generator, by transforming mechanical energy (during braking or supplied by a combustion engine) into electrical energy used to charge the battery
Implementation Method 3
a DC-to-DC converter connected between the battery and the motor
Data Source
AI summary
Disclosed is a method for managing a torque to be supplied on a shaft of an electric motor including the following steps: creating and initializing a correction data table; acquiring a torque instruction; determining a torque command; measuring the current output from the converter and measuring the current output from the battery; calculating an electrical power on the basis of the two current measurements and of the voltage; determining, on the basis of a map, a corresponding torque on the basis of the electrical power at the motor and of the rotational speed of the motor; reading the information provided by the motor relating to the torque exerted on its shaft; calculating the difference between the information provided by the motor and the torque determined on the basis of the electrical power; and updating the correction data table.