Vehicle Drive Relay Isolation With Backup Capacitor Discharge
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Solution Overview
Problem
In electrified vehicles, residual charge in the motor device may not be discharged effectively during a collision due to failure of the electronic control unit to receive a collision detection signal, leading to safety risks during rescue operations.
Innovation Solution
A vehicle drive system that includes a battery, a motor device, a relay, and first and second electronic control units. The system disconnects the electrical connection between the battery and the motor device upon receiving a collision detection signal or upon disconnection of an interlock line, and utilizes a backup power supply to activate the second electronic control unit, which executes a discharge control to remove residual charge in the capacitors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the electronic control unit executes discharge control based on collision detection signal, then residual charge is discharged, but the electronic control unit cannot receive the collision detection signal under the influence of the collision
Solution Approach 1:
The system performs preliminary discharge control before rescue operations begin. The second electronic control unit is configured to automatically execute discharge control when it detects that the first electronic control unit cannot receive the collision detection signal, ensuring residual charge is discharged in advance without waiting for the failed signal reception
Solution Approach 2:
The second electronic control unit acts as an intermediary backup when the first electronic control unit fails. It monitors the system state and takes over the discharge control function when the primary control unit cannot receive collision detection signals, ensuring the discharge function is not lost due to signal reception failure
2Reliability
If the primary power supply is disrupted during collision, then the electronic control unit cannot operate, but residual charge remains in the capacitors
Solution Approach 1:
The system prepares backup power supply and second electronic control unit in advance to cushion against the failure of the primary power supply. When collision disrupts the primary power supply, the backup power supply automatically activates to maintain discharge control functionality, preventing residual charge hazards despite power disruption
Solution Approach 2:
The system changes the power supply parameter from primary to backup when collision occurs. The second electronic control unit switches to operating on backup power supply when the primary power supply is disrupted, maintaining the ability to execute discharge control and eliminate residual charge hazards
Data Source
AI summary
In a vehicle drive system, in at least either of a case where a first ECU receives a collision detection signal or a case where an interlock line is disconnected, the first ECU controls a relay such that electrical connection between a battery and a motor device is disconnected. The motor device includes an electric motor for traveling, a PCU, a second ECU, and a backup power supply. The PCU includes one or more capacitors. When the interlock line is disconnected, the second ECU is activated by electric power supplied from the backup power supply activated along with the disconnection. Under the condition that the second ECU does not receive, from the first ECU, a discharge command to discharge residual charge or that a determination that a collision occurs is made, the second ECU controls the PCU such that the PCU executes a discharge control.