EV Relay Control via Motor Speed and Shift Position Verification
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Solution Overview
Problem
Existing relay control systems for electric vehicles fail to accurately determine whether the disconnection of a high-voltage power source is intentional or due to an abnormality, leading to potential safety and operational issues during inspection or maintenance.
Innovation Solution
A relay control system that includes an electric power line, a relay, an operation member, a state sensor, a rotational speed detector, and a shift position detector, which permits disconnection of the relay based on the rotational speed of the electric motor and the shift position of the vehicle, ensuring safe and intentional disconnection during inspection or maintenance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the relay is allowed to disconnect based solely on operation member signal, then the ease of operation is improved, but the reliability deteriorates due to inability to distinguish intentional disconnection from abnormality
Solution Approach 1:
The control device continuously monitors motor rotational speed and shift position as feedback signals to verify whether relay disconnection is intentional. When the operation member signals disconnection, the system checks if motor speed is below threshold and shift position is in P or N range before permitting disconnection, thereby distinguishing intentional operations from abnormalities while maintaining ease of use.
Solution Approach 2:
The system performs preliminary verification of motor rotational speed and shift position before allowing relay disconnection to occur. This preliminary check ensures that disconnection is only permitted under safe conditions (low speed, parking gear), preventing accidental disconnection during critical operations while still allowing intentional disconnection when appropriate.
2Productivity
If the relay disconnection is permitted without verifying motor rotational speed and shift position, then the productivity is improved by reducing unnecessary checks, but the safety deteriorates due to potential disconnection during critical operations
Solution Approach 1:
The control device performs preliminary verification of motor rotational speed and shift position before permitting relay disconnection. This ensures that disconnection is only allowed when the vehicle is in a safe state (motor speed below threshold and shift position in P or N), preventing harmful disconnections during critical operations while maintaining operational efficiency.
Solution Approach 2:
The system uses real-time feedback from motor rotational speed sensors and shift position detectors to dynamically control relay disconnection permission. This feedback mechanism ensures safety by continuously monitoring vehicle state and only permitting disconnection when conditions are safe, without unnecessarily restricting legitimate disconnection operations.
3Reliability
If the system implements comprehensive verification of motor rotational speed and shift position, then the reliability is improved by accurately determining disconnection intention, but the device complexity increases
Solution Approach 1:
The control device leverages existing multi-functional sensors (motor rotational speed detector and shift position detector) that serve multiple purposes in the vehicle control system. By reusing these existing sensors for relay disconnection verification, the system achieves high reliability without adding dedicated verification hardware, thus minimizing device complexity while accurately determining disconnection intention.
Data Source
AI summary
A relay control system for an electric vehicle includes an electric power line, a relay, an operation member, a state sensor, a rotational speed detector, a shift position detector, and a relay disconnection permitting device. The state sensor is configured to sense that a signal circuit through which a signal related to a state of the operation member flows is changed into a disconnecting operation state. The rotational speed detector is configured to detect a rotational speed of the electric motor. The shift position detector is configured to detect a shift position of the electric vehicle. The relay disconnection permitting device permits disconnection of the relay based on the rotational speed detected by the rotational speed detector and the shift position detected by the shift position detector if the state sensor senses that the signal circuit is changed into the disconnecting operation state.