Electric Drive Low-Efficiency Control for Cold-Start Torque
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Solution Overview
Problem
Battery electric vehicles (BEVs) face challenges in maintaining performance metrics at low temperatures, as existing control systems struggle to optimize electric motor control across a wide range of temperatures, particularly during cold starts.
Innovation Solution
A control system with microprocessors that executes a low-efficiency mode by increasing current supply to the rotating electrical machine, determining a high-efficiency mode current command corresponding to a commanded torque value, and adding a desired amount of inefficiency to the current command to maintain torque output at reduced temperatures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If the control system operates the rotating electrical machine at high efficiency mode at low temperatures, then energy consumption is optimized, but torque output and performance metrics deteriorate
Solution Approach 1:
The control system dynamically switches between high-efficiency mode and low-efficiency mode based on temperature conditions. At low temperatures, the system transitions to low-efficiency mode which commands higher current and angular velocity to maintain torque output, while at normal temperatures it operates in high-efficiency mode for optimal energy consumption.
Solution Approach 2:
The system changes operational parameters (current command and angular velocity) based on temperature conditions. The low-efficiency mode modifies the current command to be higher than the high-efficiency mode current command, and operates at angular velocities higher than the maximum permissible rotor angular velocity for the given torque, thereby maintaining torque output at low temperatures.
2Reliability
If the control system increases current supply to maintain torque at low temperatures, then torque output is maintained, but energy consumption increases
Solution Approach 1:
The control system dynamically adjusts current supply based on temperature conditions. The low-efficiency mode is activated only when temperature conditions require it (when ambient temperature or motor temperature is below a threshold), ensuring torque maintenance only when necessary, while returning to high-efficiency mode when temperatures are adequate.
Solution Approach 2:
The operational range is segmented into different modes: high-efficiency mode for normal temperature operation and low-efficiency mode for cold temperature operation. This segmentation allows the system to optimize for energy consumption during most of the operating range while providing torque assurance only when temperature conditions dictate.
3Use of energy by moving object
If the control system operates at maximum permissible rotor angular velocity, then energy efficiency is optimized, but torque maintenance at low temperatures becomes difficult
Solution Approach 1:
The system dynamically adjusts the maximum permissible rotor angular velocity based on temperature conditions. During cold starts or low-temperature operation, the low-efficiency mode allows operation at angular velocities higher than the maximum permissible rotor angular velocity that would be commanded in high-efficiency mode, thereby maintaining torque output when thermal conditions require it.
4Reliability
If the control system adds desired amount of inefficiency to current command, then torque output is maintained at low temperatures, but current consumption increases
Solution Approach 1:
The system changes the current command parameter based on temperature conditions. The low-efficiency mode adds a desired amount of inefficiency to the high-efficiency current command, resulting in a higher current command that maintains torque output at low temperatures. This parameter modification is applied selectively only when temperature conditions require torque maintenance.
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 low-efficiency mode quickly increases battery and motor temperatures while maintaining torque output, ensuring performance metrics are met during cold starts by operating the rotating electrical machine at higher angular velocities than typically specified.
Implementation Method 1
increasing current supplied to the rotating electrical machine to a level corresponding to operation at an angular velocity higher than the determined physical angular velocity of the rotor
Data Source
AI summary
A control system configured to control a rotating electrical machine of a battery electric vehicle (BEV), having one or more microprocessors that execute a low-efficiency mode of operation for the BEV, such that the low-efficiency mode of operation includes determining a high-efficiency mode current command corresponding to operation at a determined physical rotor angular velocity of a rotor of the rotating electrical machine at a commanded torque value, and increasing current supplied to the rotating electrical machine to a level corresponding to operation at an angular velocity higher than the determined physical angular velocity of the rotor at the commanded torque value.