EV Charging Interlock Logic for Driveaway Prevention
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Solution Overview
Problem
Existing interlock systems in electric vehicles can be vulnerable to false indications of a charging cord being attached, leading to unintended vehicle disablement, which can cause inconvenience and strand the operator, especially when the vehicle is already activated.
Innovation Solution
An interlock system that uses a cord set indicator and an electronic control unit to determine the vehicle's activation state and prevent disabling when the cord is attached only if the vehicle is deactivated, allowing the vehicle to remain operational if the cord set indicator provides a negative result or has been previously negative, and disabling the powertrain when a positive result is detected while the vehicle is deactivated.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If an interlock system uses a cord set indicator to prevent vehicle driveaway during charging, then vehicle safety is improved, but the vehicle may be falsely disabled when activated, causing operator inconvenience
Solution Approach 1:
The interlock system dynamically adjusts its behavior based on the vehicle's activation state. When the vehicle is deactivated, the system prevents driveaway if a cord set is detected. When the vehicle is activated, the system allows driveaway even if a cord set is detected, thereby resolving the contradiction between safety and operability through state-dependent logic.
Solution Approach 2:
The system changes the interlock parameter (enable/disable driveaway) based on the vehicle's activation state. The activation state serves as a parameter that modifies the interlock behavior: in the deactivated state, the interlock is active; in the activated state, the interlock is overridden. This parameter change resolves the contradiction by adapting the safety mechanism to the operational context.
2Measurement precision
If the interlock system continuously monitors the cord set indicator, then false positives are reduced, but system complexity increases
Solution Approach 1:
The system uses feedback from the vehicle's activation state to modulate the interlock behavior. The activation state provides feedback that determines whether the cord set indicator should trigger an interlock. This feedback mechanism improves detection accuracy by considering the operational context without requiring complex additional hardware.
Solution Approach 2:
The existing activation state signal, already present in the vehicle's control system, is repurposed to control the interlock behavior. This multi-functional use of the activation state signal improves cord set detection accuracy without adding dedicated complexity for interlock control, as the same signal serves dual purposes.
Data Source
AI summary
To prevent damage of a vehicle or a cord set used to charge a plug-in electric vehicle when the vehicle is driven away while the cord set is attached, an interlock can be provided to disable the vehicle. Such interlock may be based on a protective door over the charging receptacle being open or detection that a cord set is plugged in. However, in the event that the vehicle is in an activated state, the interlock is prevented from disabling the vehicle according to an embodiment of the disclosure. That is, undesirable disabling of the vehicle is prevented when either there is no indication of a cord set being coupled to the vehicle or the vehicle is in an activated state.