Vehicle Control System Adaptive Threshold for Motor Load
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Solution Overview
Problem
When a vehicle with an electric motor is switched from automatic driving to manual driving, the load factor of the electric motor is often limited due to temperature constraints, leading to reduced drive torque and vehicle response, as the existing control systems do not differentiate between automatic and manual driving modes effectively.
Innovation Solution
A control system that includes an electronic control unit capable of switching between automatic and manual driving modes, setting different threshold temperatures for the electric motor, hydraulic oil, and inverter to manage the load factor accordingly, allowing higher threshold temperatures during manual driving to ensure sufficient drive torque is delivered.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the load factor of the electric motor is limited when the temperature exceeds the threshold temperature, then the temperature rise of the electric motor is curbed and performance deterioration is prevented, but the drive torque requested by the driver is not sufficiently generated and vehicle response is reduced
Solution Approach 1:
The patent applies dynamics by making the threshold temperature adaptive rather than fixed. The control unit dynamically adjusts the threshold temperature based on the detected temperature of the electric motor, allowing the system to transition between protective load limiting and full performance modes. This resolves the contradiction by enabling the system to be protective when needed (maintaining reliability) while allowing full performance when temperatures are acceptable (maintaining vehicle response).
Solution Approach 2:
The patent changes the parameter of threshold temperature from a fixed value to a variable that adapts based on actual motor temperature conditions. When the motor temperature is below a predetermined threshold, the system allows higher operating temperatures; when the threshold is exceeded, load limiting is activated. This parameter adaptation resolves the contradiction between protecting motor performance and maintaining driver-requested vehicle response.
2Device complexity
If a single threshold temperature is used for both automatic and manual driving modes, then the control system is simple, but the driver cannot drive the vehicle as intended when switching from automatic to manual mode due to limited load factor
Solution Approach 1:
The patent makes the control system dynamic by detecting the driving mode (automatic or manual) and adjusting the threshold temperature application accordingly. In manual driving mode, the system prioritizes driver intent by allowing higher load factors even at elevated temperatures, while in automatic mode, it applies stricter thermal management. This dynamic adaptation resolves the contradiction between system simplicity and manual driving performance.
Solution Approach 2:
The patent applies different control characteristics to different driving modes. For manual driving, the system allows higher threshold temperatures and load factors to prioritize driver intent and vehicle response. For automatic driving, it applies more conservative threshold limiting for thermal management. This local differentiation resolves the contradiction by optimizing performance for each specific operating context without requiring complete system redesign.
Data Source
AI summary
A control system is installed on a vehicle having an electric motor as a drive power source. The control system includes an electronic control unit configured to switch the vehicle between an automatic driving mode using automatic drive control, and a manual driving mode in which the vehicle is operated by a driver. The electronic control unit is configured to limit the load factor of the electric motor, in the case where the temperature of the electric motor is higher than a first threshold temperature when the vehicle travels in the automatic driving mode, and the case where the temperature of the electric motor is higher than a second threshold temperature when the vehicle travels in the manual driving mode. The second threshold temperature is set to a value higher than the first threshold temperature.