Integrated Contactor Current Sensing for Fast Overcurrent Interruption
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Solution Overview
Problem
Electric vehicle and hybrid vehicle power circuits pose safety risks due to potential malfunctions, requiring rapid detection and disconnection of electrical power, which existing contactors fail to achieve efficiently, especially in high-voltage environments.
Innovation Solution
A contactor with a magnetic sensor for measuring high-voltage current, a primary switch driven by an actuator, and a fuse, integrated with a controller that autonomously detects overcurrent conditions and attempts to open the switch before blowing the fuse, reducing the need for external communication and enhancing safety and reliability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a contactor uses a simple fuse-based protection system without internal current measurement and switch status detection, then the device complexity is reduced, but the reliability and safety response time deteriorate because external communication is required for malfunction detection
Solution Approach 1:
The contactor performs self-diagnosis by internally measuring current through a magnetic sensor and detecting its own switch status, eliminating the need for external communication to detect malfunctions. The controller autonomously determines overcurrent conditions and switch state, enabling rapid safety response without increasing overall system complexity
Solution Approach 2:
The contactor implements feedback mechanisms by continuously monitoring current flow through the magnetic sensor and switch status through detection means, providing real-time information to the controller. This internal feedback loop enables the contactor to autonomously detect malfunctions and respond rapidly, improving reliability while maintaining manageable device complexity
2Reliability
If the contactor immediately blows the fuse upon detecting overcurrent, then the safety response time is improved, but the operational lifetime deteriorates due to unnecessary fuse replacement
Solution Approach 1:
The contactor performs preliminary verification by first attempting to open the switch through the actuator before blowing the fuse. The controller checks whether the switch successfully opens by detecting switch status, and only blows the fuse if the switch remains closed. This preliminary action prevents unnecessary fuse blowing and extends operational lifetime while maintaining rapid safety response
Solution Approach 2:
The contactor autonomously determines the appropriate protection action by internally assessing both current conditions and switch status. This self-service capability allows the contactor to distinguish between temporary overcurrent conditions that can be resolved by opening the switch and genuine faults requiring fuse blowing, thereby extending operational lifetime without compromising safety response time
3Productivity
If the contactor relies on external processors for current measurement and switch status detection, then the device complexity is reduced, but the productivity and safety response time deteriorate due to communication delays
Solution Approach 1:
The contactor merges the functions of current measurement, switch status detection, and control decision-making into a single integrated device. The magnetic sensor, detection means, and controller are combined within the contactor, eliminating the need for separate external processors and communication interfaces. This integration significantly improves safety response speed while keeping device complexity manageable through functional consolidation
Solution Approach 2:
The controller within the contactor performs multiple functions: it processes current measurement data from the magnetic sensor, determines overcurrent conditions, monitors switch status through detection means, and controls the actuator. This multi-functional approach eliminates the need for separate external processors, improving productivity while maintaining reasonable device complexity through universal functionality
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 contactor effectively interrupts high-voltage currents, improving safety and extending its operational lifetime by reducing unnecessary fuse blowing and relying on internal diagnostics for swift action during malfunctions.
Implementation Method 1
a magnetic sensor configured for measuring a primary current flowing through the electrical conductor portion
Data Source
AI summary
An integrated circuit includes: a magnetic sensor for outputting a magnetic sensor signal indicative of a first current in a conductor; a shunt interface for outputting a shunt signal indicative of a second current across an external shunt resistor; a processing circuit for receiving the magnetic sensor signal and the shunt signal; and a communication interface for providing a signal indicative of a measured current based on one or more of the first current and the second current. The integrated circuit can compare the magnetic sensor signal and the shunt signal and provide an output signal in response to the magnetic sensor signal and the shunt signal.