Vehicle Collision Power Cutoff With Motor Back-EMF Suppression
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Solution Overview
Problem
Existing vehicle control systems struggle to ensure electrical safety during collisions, particularly in electric vehicles with drive systems like batteries, motors, and power control units, as they fail to adequately manage voltage spikes caused by counter electromotive forces in motors.
Innovation Solution
A control device for vehicles that includes an internal combustion engine, a battery, rotary electric machines, power conversion circuits, capacitors, and a switching unit. This device executes discharge control when a collision is predicted, involving interrupting the battery power supply, stopping the motor's rotation, and discharging stored capacitor charges.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the power supply circuit is interrupted and capacitor is discharged when collision is predicted, then electrical safety is improved, but motor voltage spikes from counter electromotive force are not adequately addressed
Solution Approach 1:
The control device stops the rotary electric machine before the collision occurs, preventing the motor from generating counter electromotive force voltage spikes during the collision event. This preliminary action addresses the motor voltage issue that was not covered by existing power supply interruption and capacitor discharge methods
Solution Approach 2:
By stopping the motor rotation in advance, the system prevents the generation of harmful counter electromotive force that would otherwise occur during collision, thereby counteracting the voltage spike problem before it can affect electrical safety
2Reliability
If the switching unit interrupts battery power supply during collision, then overcurrent protection is improved, but motor rotation cannot be stopped preventing counter electromotive force generation
Solution Approach 1:
The control device stops the rotary electric machine before the collision occurs, preventing the motor from generating counter electromotive force voltage spikes during the collision event. This preliminary action addresses the motor voltage issue that was not covered by existing power supply interruption and capacitor discharge methods
Solution Approach 2:
By stopping the motor rotation in advance, the system prevents the generation of harmful counter electromotive force that would otherwise occur during collision, thereby counteracting the voltage spike problem before it can affect electrical safety
3Loss of energy
If capacitor discharge is performed after collision, then stored energy is released, but excessive short-circuit currents may occur
Solution Approach 1:
The control device stops the rotary electric machine before the collision occurs, preventing the motor from generating counter electromotive force voltage spikes during the collision event. This preliminary action addresses the motor voltage issue that was not covered by existing power supply interruption and capacitor discharge methods
Solution Approach 2:
By stopping the motor rotation in advance, the system prevents the generation of harmful counter electromotive force that would otherwise occur during collision, thereby counteracting the voltage spike problem before it can affect electrical safety
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 proposed solution effectively prevents excessive short-circuit currents, voltage spikes in motors, and unnecessary capacitor discharge after collisions, thereby ensuring electrical safety and reducing the need for protective measures like skid plates.
Implementation Method 1
a capacitor connected between the battery and the connection portions to store an electric charge
Implementation Method 2
a switching unit connected between the battery and the capacitor and configured to interrupt power supply from the battery
Implementation Method 3
when a motor rotates after a collision of a vehicle, a voltage of the motor may become high due to a counter electromotive force generated in the motor
Data Source
AI summary
A control device for a vehicle, the vehicle including: a battery; a first rotary electric machine coupled to an axle; a second rotary electric machine coupled to an internal combustion engine; a first power conversion circuit; a second power conversion circuit; a capacitor connected between the battery and connection portions connecting the first power conversion circuit and the second power conversion circuit in parallel; and a switching unit connected between the battery and the capacitor, the control device executing discharge control when a collision of the vehicle is predicted, and the discharge control includes: opening the switching unit to interrupt the power supply from the battery; stopping rotation of the first rotary electric machine if the first rotary electric machine is rotating; and discharging the electric charge stored in the capacitor.