National Highway Traffic Safety Administration

Task Force 9: Communication and Messaging

Wayne McKenzieWilliam Joel Sanchez

Task Force Leaders

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• Project Concern: The automotive application and use of a REESS, such as Lithium-ion battery based system, imposes certain safety risks to the operators and occupants of these vehicles, which are different than that of vehicles using only an internal combustion engine.

• Potential Safety Risk: Thermal runaway of the battery pack(s), which in some cases may result in fire or explosion.

• Project Scope: This research focuses on the safe management of an automotive REESS, i.e. its BMS and any electronic failures associated with it.

Background

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Goals:1. Identify diagnostic and prognostic elements based on a

comprehensive HARA of automotive REESS, specifically BMS functionality

2. Determine information and messaging needs for operators and responders

3. Write report that informs potential agency regulatory decisions

Scope:Focus on safe management of an automotive REESS; i.e., its Battery Management System (BMS) and any electronic failures associated with it.

Project Goals and Scope

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1. Delineate the hazards and their severity levels pertaining to the functional safety of automotive REESS controls, and identify safety requirements and constraints of BMS functionality

2. Define system diagnostics, prognostics, and data logging

3. Identify safety-critical information needs and effective methods to communicate this information to operators

4. Address safety-related instructions and training needs for operators

Project Objectives

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Safety Concept

Battery Management Controls: Measurement & protection of an automotive REESS, specifically the BMS and its interactions with other vehicle systems.• Fail-Safe Response to Faulted Conditions• Diagnostics/Prognostics• Sensor Validity/Integrity• Cell Voltage• Cell Temperature• Cell Balancing

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Refinement of Analytical Scope

Battery PackBattery Management System (BMS)

Controller

Battery Pack Box & Seal

Power Distribution Unit

Current Sensor

HV DC BusHV DC Bus

LV DC

CAN Bus

HVIL

Thermal Mgmt.

Coolant

Charger Mgmt.

Regen Mgmt.

Load Mgmt.

Vehicle Ground

REESS

Crash Detection

Communication Protocol

Controls/Data

Controls/Data

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Automotive REESS

• System Description – Battery Pack– Battery Management System Controller– Power Distribution Unit

• System Function– Stores electrical energy received from the charger or the

vehicle – Delivers energy to the vehicle systems– Communicates with other vehicle module for proper

vehicle functions– Maintains safe vehicle operation

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Description: – Sealed vented box – Includes the battery

modules, voltage sensors, cell voltage balancers, temperature sensors, condensation sensors, and ground fault detection circuitry

Function: – Stores electrical energy– Delivers electrical energy – Communicates cell status

and isolation status

Battery Pack

Battery Pack Box & Seal

CellVoltageBalancer

Cell Temp& VoltageSensor

GroundFaultDetection

CondensationSensor

BatteryCells

BatteryCells

BatteryCells

BatteryCells

BatteryCells

Vent

Inte

rcon

nect

sTh

erm

al C

ontr

ol

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Description:

– Algorithms including State of Charge (SOC), State of Health (SOH),

– Diagnostics and Prognostics– Communication– Data Storage– Safety Controls

Function:

– Manages the energy in and out of the battery pack based on the SOC

– Acts on safety related requests from other vehicle systems

– Maintains the safety of the REESS

Battery System Management Controller

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Description:

– Main contactor– Pre-charge contactor– Relays and fuses

Function:

– Controls connection between the battery pack and the High Voltage bus

– Ensures that the system power limits are respected

Power Distribution Unit

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REESS External Interfaces

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• Analysis must consider external vehicle interfaces in terms of their impact on the safe operation of the REESS

• REESS must tolerate external failures and maintain a safe state

Scope of External Interfaces

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Diagnostic Trouble Codes

• Breakdown of hybrid power related to sample vehicle used• 64% are related to the BMS (Brown & Orange sections)• The Motor Controller (17%) and Charging System (11%) also prominent

1%1%3% 3%

16%

35%5%8

%

17%

11%

Misc.CommunicationContactorsBattery and Eelctronics Cool-ingHV Battery Di-agnosticsHV Battery Voltage LevelHV Battery TemperatureHV Battery OtherMotor ControlerCharging

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• Identify safety-critical information needs of owners and operators

• Describe effective means to communicate this information

• Describe barriers to effective communication and opportunities to remove them

Communications and Messaging

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System Status Charge State Low Charge Discharge Rate/Range

BMW Mini E (BEV)

Chevrolet Volt (PHEV)

Fisker Karma (BEV+)

Nissan Leaf (BEV)

Tesla Roadster (BEV) (Regen Off)

Toyota Prius (PHEV)

HEV/PHEV Status Indications

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High Temp. 12V Fault REESS Fault Low Power Hazard/Other

BMW Mini E (BEV)

Chevrolet Volt (PHEV)

Fisker Karma (BEV+)

Nissan Leaf (BEV)

Tesla Roadster (BEV)

Toyota Prius (PHEV)

HEV/PHEV Malfunction Indications

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Questions