Battery Pack Relay Control for Faster Collision Isolation
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Solution Overview
Problem
In electric vehicles, the time it takes for a relay to open after a collision can lead to electrical sparks and potential fires due to the delay in blocking the high-voltage battery's electrical components, necessitating a reduction in this timeframe to minimize damage.
Innovation Solution
A vehicle system that includes a battery, an electric motor, a switch, an inertial sensor, and a controller that adjusts the duty ratio of a PWM signal based on acceleration thresholds to control the switch's opening and closing, ensuring rapid relay opening in the event of a collision.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the relay is controlled using a PWM signal with duty ratio adjustment, then the relay can be opened and closed, but it takes 10 to 30 ms for the relay to actually open even when the duty value is suddenly reduced to 0%, causing electrical sparks and potential fires
Solution Approach 1:
The patent applies preliminary action by detecting collision signals before the relay needs to open, and pre-adjusting the PWM duty ratio to prepare the relay for rapid opening. The collision detection system activates the battery management system in advance, allowing the relay to open faster by reducing the delay between collision detection and relay actuation.
2Speed
If the duty value is suddenly reduced to 0% to open the relay, then the relay should open immediately, but it still takes 10 to 30 ms for the relay to actually open due to physical limitations
Solution Approach 1:
The patent converts the harmful effect of electrical sparks during relay opening into a beneficial outcome by implementing a controlled opening sequence. The PWM duty ratio is adjusted in stages rather than instantly to 0%, which controls the arc formation and allows the relay to open faster while minimizing harmful electrical sparks through managed energy dissipation.
3Reliability
If the relay opens faster to prevent fires, then safety is improved, but the control system must respond more quickly which increases system complexity
Solution Approach 1:
The patent applies universality by integrating multiple functions into the battery management system: collision detection, PWM signal generation, relay control, and spark suppression all occur within a single control unit. This multi-functional approach improves safety response time while avoiding the need for separate dedicated systems for each function, thereby limiting the increase in overall system complexity.
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
This solution reduces the time required for the relay to open, minimizing the risk of electrical sparks and fires by anticipating and quickly responding to collision conditions, thereby reducing additional damage.
Implementation Method 1
an inertial sensor configured to output an acceleration signal
Implementation Method 2
a controller configured to output a pulse width modulation (PWM) signal having a duty ratio adjusted according to an acceleration magnitude
Implementation Method 3
a switch driving circuit configured to generate a control current for controlling the switch based on the PWM signal
Data Source
AI summary
A vehicle includes: a battery; an electric motor to be actuated by electric energy stored in the battery; a switch coupled between the battery and the electric motor; an inertial sensor configured to output an acceleration signal; a controller configured to output a pulse width modulation (PWM) signal having a duty ratio according to an acceleration magnitude of the acceleration signal; and a switch driving circuit configured to generate a control current for controlling the switch based on the PWM signal.