Electric Vehicle Control Device Pre-Limp Home Mode
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Solution Overview
Problem
Existing electric vehicle control systems fail to effectively manage the traveling state of a vehicle before an abnormality occurs in the electrically driven system, often causing uncomfortable transitions when torque or velocity limitations are enforced, and lack flexibility in responding to different types of abnormalities.
Innovation Solution
A control device for electric vehicles that includes a suppression mode function with a pre-limp home mode and a limp home mode, allowing for gradual or immediate torque and velocity limitations based on the type and severity of abnormalities, enabling smoother transitions and reduced driver discomfort by adjusting vehicle velocity and torque gain according to the traveling situation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If torque limitation is reinforced stepwise to avoid uncomfortable feeling, then driver comfort is improved, but response time to stop the vehicle increases
Solution Approach 1:
The control device dynamically adjusts the torque limitation strategy based on real-time vehicle conditions. When abnormality occurs, the system determines current vehicle velocity and torque state, then selects appropriate limitation levels (first level for gradual reduction, second level for immediate reduction) to balance comfort and response time requirements
Solution Approach 2:
The system changes torque limitation parameters adaptively based on vehicle state. Instead of fixed stepwise reduction, the control device adjusts torque gain and velocity limits according to current operating conditions, allowing faster response when needed while maintaining comfort when possible
2Reliability
If torque limitation is applied immediately when abnormality occurs, then vehicle safety is improved, but driver comfort deteriorates due to uncomfortable feeling
Solution Approach 1:
The control device implements dynamic torque limitation that adapts to vehicle state. When abnormality occurs, the system evaluates current velocity and torque conditions, then applies appropriate limitation levels - using first level limitation for gradual reduction in many cases, or second level for immediate reduction when safety requires, optimizing both safety and comfort
Solution Approach 2:
The system applies different limitation strategies to different aspects of vehicle control based on local conditions. Torque gain limitation and velocity limitation are adjusted independently according to current vehicle state, allowing selective application of comfort-oriented or safety-oriented strategies in different control dimensions
3Reliability
If torque limitation is applied in all traveling situations, then vehicle safety is improved, but device complexity increases due to need to manage different traveling conditions
Solution Approach 1:
The control device applies partial action by selecting from two limitation levels based on need. Instead of always applying maximum limitation or complex multi-level strategies, the system uses first level limitation (moderate reduction) or second level limitation (strong reduction) selectively, simplifying control logic while maintaining safety
Solution Approach 2:
The system simplifies complexity by changing control parameters adaptively between two defined states. Torque gain and velocity limits are adjusted according to predetermined maps based on vehicle state, avoiding the need for complex real-time calculations while ensuring appropriate response to different abnormality scenarios
Data Source
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AI summary
A control device for an electric vehicle including a traveling motor which is configured to transmit a driving force to driving wheels, includes: a control unit having a suppression mode function for suppressing a traveling state amount of the vehicle when an abnormality occurs in an electrically driven system of the vehicle. The suppression mode function includes a first suppression state and a second suppression state, and a suppression degree in the second suppression state is smaller than a suppression degree in the first suppression state. In accordance with a kind of the abnormality in the electrically driven system, the control unit is configured to cause the vehicle to be in the first suppression state or is configured to cause the vehicle to be in the first suppression state after causing the vehicle to be in the second suppression state.