Pre-charge Circuit Bypassing Relay to Manage Current Thresholds
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Solution Overview
Problem
Existing systems for pre-charging electrical loads in hybrid or electric vehicles do not efficiently manage current flow to prevent relay closure, leading to potential overcharging and inefficiencies in energy transfer between the traction battery and electrical loads.
Innovation Solution
A system comprising a relay and coil contactor with a controller that bypasses the relay to allow controlled current flow through the coil, enabling pre-charging of electrical loads by selectively enabling current from the traction battery to flow through the coil before the relay closes, thus managing current thresholds to prevent overcharging.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If current flows through the relay during pre-charge, then the relay closure is controlled, but the pre-charge efficiency is reduced and energy is wasted
Solution Approach 1:
The circuit is segmented into two separate paths: one path through the relay for normal operation control, and another bypass path through the switch for pre-charge current flow. This segmentation allows the pre-charge current to flow independently without passing through the relay, eliminating energy waste while preserving relay control functionality for actual load operation.
Solution Approach 2:
The pre-charge switch enables preliminary current flow to the load before the relay closes. By performing the pre-charge action in advance through the bypass path, the load is partially charged before full power connection, reducing the inrush current and energy waste when the relay closes, while maintaining proper relay control.
2Productivity
If the relay closes immediately when current is applied, then the circuit is completed quickly, but the load may be overcharged and energy transfer is inefficient
Solution Approach 1:
The controller performs preliminary charging of the load through the pre-charge switch before closing the relay. This preliminary action allows the load to reach an appropriate charge level gradually, preventing overcharging and improving energy transfer efficiency by controlling the charging sequence and timing.
Solution Approach 2:
The system dynamically controls the charging process by first enabling pre-charge current flow through the switch, monitoring the charge level, and then closing the relay at the appropriate moment. This dynamic control sequence optimizes energy transfer efficiency while preventing load overcharge through staged charging.
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 solution allows for efficient pre-charging of electrical loads by ensuring the relay closes only when the current threshold is met, reducing energy wastage and ensuring safe and controlled energy transfer, thereby optimizing the vehicle's energy management system.
Implementation Method 1
the relay configured to close in response to a magnitude of current through the coil being greater than a first threshold
Data Source
AI summary
A vehicle system includes a relay and coil of a contactor. The relay is configured to transfer current between a traction battery and an electrical load when closed. The system also includes a controller configured to operate a switch such that current flow from the traction battery through the coil and switch, and bypassing the relay, causes the relay to close to permit pre-charging of the load.