Ground Fault Detection in Secondary Battery Systems
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Solution Overview
Problem
Existing ground fault detection systems in assembly battery systems using secondary cells are either too slow or require additional components like breakers, making them impractical for rapid fault identification and recovery.
Innovation Solution
A ground fault detecting device with voltage dividing resistances, a ground fault detecting resistance, a current direction determining circuit, and a display circuit that can quickly identify the fault location without the need for breakers or changeover switches, by measuring current through the resistances and determining current direction to specify the fault spot.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the ground fault detecting device according to Literature 1 is applied to the assembly battery system, then ground fault detection is achieved, but it takes much time to identify a ground fault spot and recovery is delayed
Solution Approach 1:
The assembly battery is divided into multiple battery groups (positive battery groups and negative battery groups), each with dedicated detecting resistances. This segmentation allows the ground fault detection to be localized to specific groups rather than requiring systematic checking of the entire battery, significantly reducing the time to identify the fault spot while maintaining reliable detection capability.
2Measurement precision
If the ground fault detecting device according to Literature 2 is used, then ground fault spot identification is possible, but breakers must be provided for each cell group which is not feasible due to design restrictions
Solution Approach 1:
Instead of using breakers for each cell group, the invention introduces ground fault detecting resistances as intermediary components connected to the cathodes and anodes of the battery groups. These resistances serve as mediators that enable precise ground fault spot identification through voltage measurements, achieving the same diagnostic capability without requiring complex breaker infrastructure for each group.
3Speed
If voltage dividing resistances and ground fault detecting resistance are used to measure current direction, then rapid ground fault position specification is achieved, but additional circuit components are introduced
Solution Approach 1:
The voltage dividing resistances and ground fault detecting resistance are designed to serve multiple functions: they enable rapid ground fault position specification through current direction measurement, provide continuous monitoring capability, and integrate seamlessly with the existing battery structure. This multi-functionality justifies the additional circuit components by delivering comprehensive diagnostic capabilities that significantly improve fault identification speed.
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 rapid and accurate detection of ground fault positions in assembly battery systems, improving recovery times and versatility by eliminating the need for additional hardware and complex operations.
Implementation Method 1
two voltage dividing resistances which are connected in series between a cathode and an anode of the assembly battery... the two voltage dividing resistances have the same resistance value... the voltage of the assembly battery is equally divided from a middle point
Implementation Method 2
a ground fault detecting resistance having one terminal connected to the middle point and having the other terminal end grounded... measures a current running through the ground fault detecting resistance
Implementation Method 3
a current direction determining circuit which determines a direction of the current... specifies a ground fault spot in the assembly battery in accordance with a direction of the current
Data Source
AI summary
A secondary battery system includes an assembly battery (2) which are composed of secondary cells (P11~P46), two voltage dividing resistances (31A and 31B) which equally divide a voltage across a cathode and an anode of the assembly battery (2) from the intermediate point, a ground fault detecting resistance (32) which grounds the intermediate point, a ground fault detector (33) for detecting a ground fault in accordance with a current running through the ground fault detecting resistance (32), and a ground fault spot determining circuit (34) for determining whether a ground fault spot is on a cathode side (GP) or an anode side (GN) of the assembly battery (2) in accordance with the direction of the current running through the ground fault detecting resistance (32).