Vehicle Impact Detection Circuit With Dynamic Threshold Switching
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Solution Overview
Problem
Secondary batteries in electric vehicles may experience high voltage/high current during external impacts, posing a risk of human injury, and existing impact detection systems struggle to differentiate between various impact conditions effectively.
Innovation Solution
A vehicle impact detection device that includes an amplifier, comparative voltage circuit, and comparator to detect impact conditions by reducing a reference signal over time and cut off battery output based on predefined conditions, using a single comparator to distinguish between different impact detection conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If multiple impact detection conditions are set to detect various impact directions and intensities, then the detection accuracy and safety coverage are improved, but the device complexity and manufacturing cost increase due to requiring multiple comparators
Solution Approach 1:
A single comparator is designed to perform multiple detection functions by dynamically changing its reference voltage level. The comparator can detect both first impact detection conditions (higher threshold) and second impact detection conditions (lower threshold) by adjusting the reference voltage, eliminating the need for separate comparators for each detection condition. This multi-functional design reduces device complexity while maintaining comprehensive impact detection capability.
Solution Approach 2:
The reference voltage level of the comparator is dynamically changed based on the detection state. Initially, the comparator uses a first reference voltage level to detect high-intensity impacts. After detecting an impact signal, the reference voltage is switched to a second, lower level to detect additional impact conditions. This parameter change enables one comparator to effectively perform the work of multiple comparators with different fixed thresholds.
2Device complexity
If a single comparator is used to detect multiple impact conditions, then the device complexity and manufacturing cost are reduced, but the ability to distinguish between different impact conditions may be compromised
Solution Approach 1:
The impact detection process is divided into distinct time periods or phases. In the first period, the comparator operates with a first reference voltage level to detect high-intensity impacts. After an impact is detected, the system transitions to a second period where the reference voltage level is changed to detect additional impact conditions. This periodic operation ensures that different impact conditions are detected at appropriate times without interference, maintaining detection precision while using a single comparator.
Solution Approach 2:
The system performs preliminary detection using the first reference voltage level before switching to the second reference voltage level. By first establishing whether a high-intensity impact occurred, the system can then appropriately adjust the reference voltage to detect lower-intensity or different types of impacts. This preliminary action ensures that the single comparator systematically evaluates different impact conditions in a structured sequence, preventing missed detections.
Data Source
AI summary
A vehicle impact detection device includes: an amplifier configured to receive and amplify an impact signal of a vehicle; a comparative voltage circuit configured to generate a first reference signal; a first comparator configured to output a control signal indicating that a predetermined first impact detection condition or a predetermined second impact detection condition is satisfied, based on an amplified signal output by the amplifier and the first reference signal; and a driver configured to cut off an output of a battery on basis of the control signal, wherein the comparative voltage circuit is configured to reduce a magnitude of the first reference signal over time in response to detection of the amplified signal output by the amplifier.