EV Power Bus Fault Isolation Using Bidirectional MOSFET Switches

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Solution Overview

Problem

Existing electric vehicle power architectures face challenges in efficiently isolating faults on direct current to direct current (DCDC) and low voltage battery buses while maintaining critical vehicle functions, often requiring high-dissipation diodes that increase cost and complexity.

Innovation Solution

A power architecture using bidirectional metal-oxide-semiconductor field-effect transistor (MOSFET) based switches with tuned switching thresholds for DCDC and low voltage battery buses, allowing selective fault isolation and redundant power paths without high-dissipation diodes, utilizing an isolator switch for DCDC bus and a bidirectional switch for the low voltage battery bus.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If high-dissipation diodes are used for fault isolation, then fault isolation capability is improved, but device complexity and cost increase

Engineering Contradiction:

Improvefault isolation capabilityVSAvoiddevice complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The patent changes the operational parameters of MOSFET switches by tuning their gate-source voltage thresholds. The first MOSFET switch is configured with a higher gate-source voltage threshold than the second MOSFET switch, enabling selective fault isolation based on voltage levels without requiring complex diode circuits

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent replaces the mechanical/diode-based fault isolation system with an electronic MOSFET-based system. Instead of using passive high-dissipation diodes that require thermal management and complex circuitry, the invention uses actively controlled MOSFET switches that can be precisely controlled through gate voltage signals

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

2Reliability

If high-dissipation diodes are used for fault isolation, then fault isolation capability is improved, but manufacturing cost increases

Engineering Contradiction:

Improvefault isolation capabilityVSAvoidmanufacturing cost

Core Design Contradiction:

ReliabilityVSEase of manufacture

Solution Approach 1:

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent employs standard MOSFET switches that are generally more cost-effective and easier to manufacture than high-dissipation diodes. The MOSFETs can be integrated into existing power management ICs, reducing overall manufacturing costs compared to discrete diode solutions

Inventive Principle:

Principle #27Cheap short-living objects (Disposable)

3Reliability

If redundant power paths are implemented, then system reliability is improved, but device complexity increases

Engineering Contradiction:

Improvesystem reliabilityVSAvoiddevice complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The patent implements dynamic control of the MOSFET switches based on real-time fault detection. The control system monitors the health of power buses and dynamically switches between redundant paths only when needed, rather than maintaining complex permanent redundant circuitry. This reduces overall system complexity while ensuring reliability when required

Inventive Principle:

Principle #15Dynamics

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 fault isolation in electric vehicles, maintaining critical vehicle functions by isolating faulty buses and powering remaining healthy buses, reducing material costs and complexity, while ensuring redundancy and health monitoring.

Implementation Method 1

bidirectional metal-oxide-semiconductor field-effect transistor (MOSFET) based switches with tuned switching thresholds

Methodology Applied

Scientific EffectMOSFET switching: Conduction (electrical)

Data Source

PatentUS20250340133A1High current fault isolation for electric vehicles

Publication Date: 2025.11.06 RIVIAN HOLDINGS LLC

AI summary

A fault isolation system for electric vehicles may include an electronic control unit with an isolator switch connected to a direct current to direct current bus and a bidirectional switch connected to a low voltage battery bus. When a fault occurs on either bus, the corresponding switch opens while maintaining power through the alternate bus, enabling vehicle functions to continue operation.