Parallel Battery Relay Fault Isolation Using Diagnosis Current Paths
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Solution Overview
Problem
In parallel pack battery systems, it is challenging to accurately diagnose which relay has a fault among multiple relays connected in common, as the fault can only be identified by voltage measurements at the load side contacts, without specifying the individual relay.
Innovation Solution
A relay diagnosis apparatus and method that includes a diagnosis unit with a switch and resistor connected between battery pack terminals, detectors for current and voltage measurements, and a control unit to determine if relays have stuck-closed faults by analyzing detection values and thresholds during specific operational states.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If voltage measurements are used at load side contacts to detect relay faults, then fault detection capability is provided, but individual relay identification is impossible in parallel pack assemblies
Solution Approach 1:
The patent divides the common load side contact measurement into individual relay-specific measurements by introducing separate measurement paths. Each relay's load side contact is measured individually through its own measurement circuit, allowing precise identification of which specific relay has a fault while maintaining the ability to detect faults in parallel pack assemblies.
2Measurement precision
If separate measurement paths are introduced for each relay, then individual relay identification is achieved, but device complexity increases
Solution Approach 1:
The patent designs measurement circuits that can serve multiple functions: they can measure individual relay contacts separately for precise fault identification, and they can also work together as a unified system for overall system monitoring. The measurement unit is designed to handle both individual and collective measurements, reducing the need for completely separate measurement systems for each relay.
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 individual diagnosis of faults in relays within parallel pack battery systems, allowing for precise identification and addressing of faulty relays, thereby improving system reliability and fault isolation.
Implementation Method 1
a first detector configured to detect a first module current which is an electric current flowing through the first battery module
Implementation Method 2
a second detector configured to detect a second module current which is an electric current flowing through the second battery module
Implementation Method 3
determine whether the first positive relay has a stuck-closed fault based on the first detection value and a first threshold
Data Source
AI summary
A relay diagnosis apparatus for a parallel pack assembly including a first battery pack having a first battery module and a first positive relay and a second battery pack having a second battery module and a second positive relay includes a diagnosis unit including a diagnosis switch and a diagnosis resistor connected between first and second battery pack terminals, a first detector to detect a current of the first battery module, a second detector to detect a current of the second battery module, and a control unit to collect a first and second detection values from the first and second detectors, respectively, during a first diagnosis period in which the first and second positive relays are open and the diagnosis switch is closed. The control unit determines a stuck-closed fault of the first or second positive relays based on the first and second detection values and a first threshold.