Dynamic Current Limits for BEV Motor Torque Under Thermal Load
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Solution Overview
Problem
Existing control systems for electric machines in battery electric vehicles (BEVs) struggle to efficiently and optimally regulate the supply of AC current, particularly in managing torque and current limits based on thermal and power loss considerations.
Innovation Solution
A control system that includes a microprocessor configured to determine the rated maximum current of a rotating electrical machine, receive temperature sensor inputs, and generate a modified torque command based on the received sensor data, incorporating power loss and thermal modeling to dynamically adjust current limits.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the control system uses a fixed rated maximum current for the rotating electrical machine, then the system design is simple, but the system cannot optimally regulate AC current supply under varying thermal conditions
Solution Approach 1:
The patent implements dynamic current limits by continuously monitoring temperature sensor inputs and adjusting the maximum current command accordingly. The control system transitions from a fixed rated maximum current to a variable current limit that adapts to real-time thermal conditions, allowing optimal current regulation while managing thermal constraints through dynamic adjustment rather than static design
Solution Approach 2:
The control system incorporates temperature sensor feedback to continuously monitor thermal conditions and adjust the maximum current command. This feedback mechanism enables the system to respond to changing thermal states and optimize current supply dynamically, resolving the contradiction between adaptability and complexity through intelligent control
2Productivity
If the control system dynamically adjusts current limits based on temperature, then current regulation efficiency is improved, but the control system complexity increases
Solution Approach 1:
The control system performs self-regulation by automatically adjusting current limits based on its own temperature sensor readings. The system monitors its thermal state and independently modifies the maximum current command without external intervention, improving regulation efficiency while keeping the control architecture self-contained and manageable
Solution Approach 2:
The system dynamically changes the current limit parameter based on temperature conditions. By modifying the maximum current command according to real-time thermal measurements, the system optimizes current regulation efficiency while using a straightforward parameter adjustment approach rather than complex control algorithms
3Reliability
If the control system monitors temperature and adjusts current limits, then thermal management is improved, but the measurement and control requirements increase
Solution Approach 1:
The control system proactively monitors temperature and adjusts current limits before thermal damage can occur. By continuously measuring temperature and preemptively modifying current commands in response to thermal trends, the system improves thermal management reliability while using straightforward temperature sensing and conditional control logic
Data Source
AI summary
A control system for generating a modified torque command for a rotating electrical machine in a battery electric vehicle (BEV) includes a microprocessor, capable of reading executable commands stored in non-volatile memory, configured to electrically connect to an inverter, determine a rated maximum current of the rotating electrical machine, receive sensor input indicating a temperature or estimating the temperature of at least one portion of the BEV, output a modified maximum current based on the received sensor input, and generate a torque command to the rotating electrical machine based on the modified maximum current.