EPS Motor Current Control via Temperature Sensing
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Solution Overview
Problem
Existing motor control systems for electric power steering (EPS) systems have low prediction accuracy for determining if a DC motor is overheated, leading to inaccurate determination of motor overheating due to its relatively high thermal capacity.
Innovation Solution
A motor control apparatus and method that includes a temperature sensing unit and an output control module to adjust the motor current based on the motor current and temperature of the motor controller, using a limit value detection unit, adjustment quantity detection unit, and output adjustment unit to limit the motor current, dividing the adjustment quantity into regions to manage temperature effectively.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If temperature prediction is performed using motor controller parameters (temperature, current, resistance, reactance), then the control system can monitor motor temperature, but the prediction accuracy is low for DC motors with high thermal capacity
Solution Approach 1:
The patent introduces a dedicated temperature sensing unit as an intermediary device that directly measures the motor controller's temperature. This mediator provides accurate temperature data without relying on complex prediction models, thereby improving measurement precision while maintaining simple control logic.
Solution Approach 2:
The patent replaces the complex thermal prediction model (which requires multiple parameters like resistance, reactance, and current calculations) with a direct temperature sensing approach. This substitution eliminates the need for complex computational mechanics while achieving accurate temperature monitoring.
2Force
If motor current is increased to provide sufficient auxiliary steering torque, then steering assistance is improved, but the motor may overheat
Solution Approach 1:
The patent implements a feedback control mechanism where the output control module continuously monitors the motor controller's temperature and adjusts the motor current accordingly. When temperature increases, the system reduces current to prevent overheating; when temperature is acceptable, the system allows higher current for sufficient steering torque.
Solution Approach 2:
The patent makes the motor current dynamic rather than fixed. The output control module adjusts the motor current in real-time based on temperature conditions, allowing the system to optimize between providing sufficient steering torque and preventing motor overheating under varying operating conditions.
3Reliability
If protection logic is implemented to limit motor output, then motor overheating is prevented, but the auxiliary steering torque is reduced
Solution Approach 1:
The patent implements dynamic output limitation where the motor current limit is adjusted based on real-time temperature measurements. Rather than using a fixed conservative limit, the system allows higher current output when temperature is low and reduces the limit only when temperature approaches dangerous levels, thereby maintaining reliability while minimizing impact on steering torque.
4Measurement precision
If existing temperature prediction models are used, then motor temperature can be monitored, but the logic complexity is high
Solution Approach 1:
The patent replaces complex thermal prediction calculations with a simple direct temperature sensing approach. The temperature sensing unit provides ready-to-use temperature data, eliminating the need for complex computational models involving resistance, reactance, and thermal capacity calculations.
Solution Approach 2:
The temperature sensing unit performs the temperature measurement function independently and directly, providing accurate temperature data to the output control module without requiring complex processing or prediction algorithms. This self-service approach simplifies the overall control logic while maintaining monitoring capability.
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 solution effectively protects the motor from overheating by accurately adjusting the motor current based on the motor controller's temperature, reducing the risk of motor damage and operating abnormalities while maintaining low logic complexity compared to existing temperature prediction models.
Implementation Method 1
a temperature sensing unit configured to sense a temperature of a motor controller
Data Source
AI summary
Disclosed are a motor control apparatus and method in an electric power steering (EPS) system for a vehicle. The motor control apparatus of an EPS system for a vehicle includes a temperature sensing unit configured to sense a temperature of a motor controller for controlling the motor in the EPS system and an output control module configured to adjust a motor current, applied from a steering control module of the EPS system to the motor, based on the motor current and the temperature of the motor controller sensed by the temperature sensing unit.