Fast-Charge Contactor Layout for HV Battery Isolation Fault Detection

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Solution Overview

Problem

Conventional high voltage Battery Management Systems (BMS) face challenges in achieving functional safety, reliability, and cost-effectiveness due to the use of multiple contactors, which are expensive, space-consuming, unreliable, and noisy, and require complex communication between separate modules for redundancy and fault detection, with FMVSS 305 not specifying isolation fault locations.

Innovation Solution

The BMS integrates the EVCC functions into the BPC, eliminates one FC contactor, and employs an improved isolation algorithm to determine fault location, reducing wiring and communication complexity while maintaining safety through consolidated software controls.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If two fast charge contactors are used in conventional BMS, then functional safety and redundancy are improved, but device complexity and cost increase

Engineering Contradiction:

Improvefunctional safetyVSAvoidcontactor configuration

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The patent extracts the EVCC functions from a separate module and integrates them into the BPC, eliminating the need for standalone EVCC hardware and reducing overall system complexity while maintaining safety functions

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The patent combines the BPC and EVCC into a single integrated unit, merging their functions and reducing the number of separate modules and communication interfaces needed, thereby simplifying the system architecture

Inventive Principle:

Principle #5Merging (Combining)

2Reliability

If multiple contactors are used for redundancy, then reliability is improved, but cost and space consumption increase

Engineering Contradiction:

Improvedual failure protectionVSAvoidmanufacturing cost

Core Design Contradiction:

ReliabilityVSEase of manufacture

Solution Approach 1:

The patent replaces mechanical contactors with solid-state relay sets, eliminating moving parts and mechanical wear, which reduces maintenance needs and improves reliability while using fewer components

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent changes the state of the contactor from mechanical to solid-state, fundamentally altering the operational parameters and failure modes to achieve better reliability with reduced component count

Inventive Principle:

Principle #35Parameter changes

3Reliability

If separate EVCC module is used, then functional safety is maintained, but communication complexity and response time increase

Engineering Contradiction:

Improvesafety protectionVSAvoidcommunication delay

Core Design Contradiction:

ReliabilityVSLoss of time

Solution Approach 1:

The patent merges the EVCC and BPC into a single integrated controller, eliminating inter-module communication delays and enabling direct, immediate response to fault conditions while maintaining all safety functions

Inventive Principle:

Principle #5Merging (Combining)

Data Source

PatentUS12403780B2Low cost fast charge contactor for high voltage battery management systems

Publication Date: 2025.09.02 FORD GLOBAL TECH LLC

AI summary

A battery management system (BMS) connected to a battery having a positive end and a negative end, the BMS also connected to a fast charger. The BMS includes: a battery management controller protection circuit board (PCB) configured to manage an operation of the battery; a charger controller PCB configure to control fast charging of the battery; and a fast charge contactor positioned between one of the positive and negative ends of the battery and the fast charger. No fast charge contactor is positioned between the other of the positive and negative ends of the battery and the fast charger. The BMS is configured to determine a location of an isolation fault by connecting and disconnecting one or more resistors.