Aggregated Battery Ground Fault Isolation by Pack Sequencing
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Solution Overview
Problem
Current methods for detecting ground faults in electric work vehicles are inefficient and costly, as they require multiple isolation monitors, which can interfere with each other, and do not allow for detection during charging or when batteries are loose.
Innovation Solution
A method and apparatus that utilize a single isolation monitor connected to a battery management system service tool and contactors to sequence the connection of each battery pack in an aggregated battery, allowing for the identification and disconnection of faulty packs without the need for multiple monitors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If multiple isolation monitors are installed in each battery pack to identify ground faults, then ground fault detection capability is improved, but device complexity and cost increase
Solution Approach 1:
The patent combines multiple isolation monitor functions into a single isolation monitor by using a sequencing mechanism controlled by a controller. The controller sequentially connects each battery pack to the single isolation monitor through contactors, allowing one monitor to perform the work of multiple monitors without interference, thus reducing device complexity while maintaining detection capability.
Solution Approach 2:
The patent implements periodic action by sequentially testing each battery pack in turn rather than having all monitors operate simultaneously. The controller activates contactors in sequence to connect each battery pack to the isolation monitor for a predetermined time period, allowing the single monitor to periodically check each pack without interference from other monitors.
2Measurement precision
If multiple isolation monitors are installed to detect ground faults in individual battery packs, then identification accuracy is improved, but interference between monitors increases
Solution Approach 1:
The patent extracts the potential interference problem by separating the testing of each battery pack in time rather than space. The controller manages contactors to ensure only one battery pack is connected to the isolation monitor at any given time, effectively removing the interference that would occur if multiple monitors operated simultaneously by using a single monitor sequentially.
Solution Approach 2:
The patent introduces dynamic control through the controller and contactors that actively manage the connection state of each battery pack. The system dynamically switches which battery pack is connected to the isolation monitor based on the testing sequence, ensuring that only one pack is tested at a time to eliminate interference while maintaining accurate fault identification.
3Reliability
If conventional ground fault detection methods are used, then machine level detection is achieved, but serviceability and loose battery testing capability are reduced
Solution Approach 1:
The patent makes the ground fault detection system universal by designing it to work in multiple scenarios: both when batteries are installed in the vehicle and when they are loose during servicing. The isolation monitor can be connected directly to the aggregated battery terminals, enabling the same system to perform both machine-level detection and service-level testing without requiring separate systems, thus improving ease of operation.
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
Enables efficient and cost-effective location and isolation of faulty battery packs, allowing for timely replacement and reducing the need for multiple isolation monitors, while enabling ground fault detection during charging or when batteries are loose.
Implementation Method 1
Such a ground fault may be detected by using an isolation monitor to measure resistances
Data Source
AI summary
A method of performing a ground fault test on an aggregated battery for an electric work vehicle. The aggregated battery is not connected to the electric work vehicle, and includes a plurality of battery packs. A plurality of contactors are configured to facilitate connection to a circuit and disconnection from the circuit of each of the plurality of battery packs. A ground fault detection tool is connected to the circuit and to a battery management system service tool. If the isolation monitor detects existence of a ground fault, the plurality of contactors are opened. Closure of the plurality of contactors is sequenced to include each of the plurality of battery packs in the circuit with the isolation monitor in turn. The isolation monitor is used to determine whether the battery pack that is included in the circuit comprises a faulty battery pack. The faulty battery pack is disconnected.