Contactor Fuse Backup for Failed Switch Opening
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Solution Overview
Problem
Existing electric and hybrid vehicle power circuits face challenges in rapidly detecting and responding to malfunctions, particularly in high-voltage environments, which can pose safety risks to passengers due to the potential for delayed disconnection of electrical loads during events like collisions.
Innovation Solution
A contactor system with a magnetic sensor and controller that measures high-voltage currents, detects overcurrent conditions, and autonomously opens a primary switch or blows a fuse if the switch fails to open, ensuring rapid disconnection without relying on external communication, thereby enhancing safety and reliability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a contactor system uses a primary switch to disconnect electrical loads, then the device complexity is reduced and ease of operation is improved, but the reliability deteriorates because the switch may fail to open properly during malfunctions
Solution Approach 1:
The system implements a backup fuse mechanism that is prepared in advance to compensate for potential switch failure. The controller monitors switch status and automatically activates the fuse as a predetermined backup measure when the switch fails to open, ensuring reliability without requiring complex manual intervention systems.
Solution Approach 2:
The system employs a detection means that continuously monitors whether the primary switch is actually open or closed and feeds this information back to the controller. The controller uses this feedback to determine if the switch has failed to open and subsequently activates the fuse, creating a closed-loop control system that enhances reliability through real-time monitoring and automatic correction.
2Loss of time
If the system blows the fuse immediately when overcurrent is detected, then the safety response time is improved, but the contactor lifetime deteriorates due to unnecessary fuse blowing
Solution Approach 1:
The system dynamically adjusts the fuse activation strategy based on real-time switch status feedback. Instead of a static immediate-response approach, the controller waits for a predetermined time to allow the switch to naturally open, then uses detection means to verify actual switch status. This dynamic approach enables timely safety response only when truly necessary, preventing premature fuse blowing and extending contactor lifetime.
Solution Approach 2:
The system performs preliminary waiting and verification actions before activating the fuse. The controller allows a predetermined time for switch opening and uses detection means to preliminarily assess whether the switch has actually opened. This preliminary assessment prevents unnecessary fuse activation, thereby extending contactor lifetime while maintaining safety readiness.
3Device complexity
If the system relies on external communication to detect malfunctions, then the device complexity is reduced, but the response speed deteriorates and cannot meet the 5 ms detection requirement
Solution Approach 1:
The contactor system performs self-diagnosis through an integrated detection means that autonomously monitors switch status without requiring external communication systems. The controller within the contactor directly receives feedback from the detection means and independently determines whether to activate the fuse, enabling the system to meet the 5 ms detection requirement through self-contained, rapid local decision-making.
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 system effectively reduces the risk of damage and injury by ensuring rapid disconnection of electrical loads, improving safety and extending the contactor's lifetime by minimizing unnecessary fuse blowing.
Implementation Method 1
a magnetic sensor configured for measuring a primary current flowing through the electrical conductor portion
Data Source
AI summary
A contactor includes: a first and second power terminal; a sub-circuit connected between this first and second power terminal and comprising the following three elements connected in series: an electrical conductor portion, a primary switch, and a fuse. The primary switch has a movable part driven by an actuator. The contactor further has a magnetic sensor for measuring a primary current flowing through the electrical conductor portion, and a controller connected to the magnetic sensor and to the actuator. The controller has a communication port for receiving commands. The contactor can detect whether the primary switch is actually open. The controller is configured for: (i) receiving a command to open the switch; (ii) operating the actuator, (iii) detecting if the primary switch is actually open; and (iv) blowing the fuse if the switch is not open.