HV Disconnect Mechanism with LV Circuit Segmentation
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Solution Overview
Problem
In high voltage electrical systems of vehicles, there is a need for a safe and reliable method to manually open the HV electrical circuit, especially for maintenance purposes, as existing contactors may not adequately prevent arcing and require complex resistor detection systems.
Innovation Solution
An electrical system that includes a contactor with a coil and a low voltage circuit connected to it, where a disconnect mechanism can selectively energize the coil to open the contacts, reducing the risk of arcing and eliminating the need for high-temperature resistant contacts by opening the low voltage circuit first, thereby safely disconnecting the high voltage circuit.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a contactor is used to open the HV electrical circuit, then the circuit can be opened, but arcing occurs and contacts may be damaged
Solution Approach 1:
The system separates the HV and LV circuits with isolated contactors for each voltage level. The LV contactor opens the low voltage circuit first, preventing arcing in the HV circuit when its contactor opens. This segmentation of circuits and timing of operations eliminates the harmful arcing effect while maintaining reliable circuit opening capability.
2Measurement precision
If resistor detection systems are used to detect high temperature, then detection is possible, but device complexity increases
Solution Approach 1:
The system uses the existing resistance change of the coil windings due to temperature rise as a self-indicating feature. The controller monitors the resistance change of the first contactor coil to detect high temperature conditions and prevents operation accordingly. This self-service approach eliminates the need for separate temperature sensors or complex detection systems while maintaining accurate temperature monitoring capability.
3Ease of operation
If the HV circuit is opened directly, then circuit opening is achieved, but safety is compromised due to arcing
Solution Approach 1:
The system performs a preliminary action by opening the LV circuit first through the second contactor before opening the HV circuit. This preliminary de-energization of the LV side eliminates the conditions that would cause arcing in the HV circuit, thereby ensuring maintenance safety while maintaining ease of operation through a standardized two-step opening sequence.
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 configuration reduces the risk of arcing and extends the lifespan of the disconnect mechanism, allowing for safe manual opening of the HV circuit without the need for high-temperature resistant contacts or resistor-based detection systems, enhancing maintenance safety and reducing the risk of damage.
Implementation Method 1
a coil configured to electrically close and open the contacts
Data Source
AI summary
An electrical system includes a contactor having a pair of contacts and a coil configured to electrically close and open the contacts. The electrical system also includes a high voltage (“HV”) circuit including a power supply electrically connected to at least one of the contacts of the contactor. The electrical system further includes a low voltage (“LV”) circuit electrically connected to the coil and configured to selectively energize the coil of the contactor. A disconnect mechanism is coupled with the LV electrical circuit and operable to electrically open the LV electrical circuit to actuate electrical opening of the contacts of the contactor.