Electric Motor Regenerative Torque Control via Battery Voltage Thresholds
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Solution Overview
Problem
Electric vehicles face challenges in maintaining optimal battery voltage and torque delivery due to limitations in regenerative torque control, leading to reduced performance and potential battery damage when fully charged or discharged.
Innovation Solution
A method for controlling an electric machine that limits recuperative torque based on battery cell voltage thresholds, using closed-loop regulation with a proportional integral regulator to manage mechanical torque and power supply, ensuring the battery voltage remains within safe limits.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If the electric motor operates in generator mode to maximize regenerative braking torque, then the braking capacity is improved, but the battery voltage increases excessively which may damage the battery
Solution Approach 1:
The control system continuously monitors battery voltage and adjusts the regenerative braking torque in real-time. When voltage reaches a threshold, the system reduces torque to prevent overcharging, creating a closed-loop feedback mechanism that balances braking performance with battery protection
Solution Approach 2:
The system dynamically adjusts the regenerative braking torque based on real-time battery state. Instead of fixed torque limits, the control adapts torque levels according to battery charge state, temperature, and voltage conditions, optimizing braking capacity while preventing damage
2Use of energy by moving object
If the battery is discharged to maximize driving range, then the energy efficiency is improved, but the electric motor can no longer provide maximum engine torque
Solution Approach 1:
The system performs preliminary charging actions during coasting or low-power phases by enabling regenerative braking to recharge the battery before high-power demands occur. This anticipatory energy management ensures torque availability when needed while maximizing overall driving range
3Reliability
If the voltage threshold for regenerative torque limitation is set low, then the battery protection is improved, but the braking capacity is reduced
Solution Approach 1:
The voltage threshold is not fixed but dynamically adjusted based on battery state of charge, temperature, and aging characteristics. The system uses adaptive threshold management to maintain optimal protection levels while preserving maximum braking capacity under varying operating conditions
Solution Approach 2:
The system changes the voltage threshold parameter based on multiple factors including battery charge level, temperature conditions, and battery health state. This parameter adaptation allows the same battery to operate safely across different conditions while maintaining optimal braking performance
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 optimizes regenerative torque limitation, preventing battery overvoltage and enhancing vehicle performance by maintaining optimal torque delivery and battery health.
Implementation Method 1
The regulation can use a proportional integral type regulator
Data Source
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AI summary
The method involves limiting regenerative torque provided by an electric motor, where limiting process is activated when electric voltage at terminals of cells (31, 32) of a battery (3) is greater than threshold. The limiting process is deactivated when electric voltage at terminals of the cells of the battery is lower than another threshold, where each cell is mounted in series with direct current generators (41, 42) and internal resistors (51, 52). Independent claims are also included for the following: (1) a computer readable recording medium comprising a computer program for executing a method for controlling an electric machine (2) a device for controlling an electric machine with an electric motor driving a drive wheel of a motor vehicle (3) a driving system for a motor vehicle, comprising a control device (4) a computer program comprising a code for executing a method for controlling an electric machine.