EVS28KINTEX, Korea, May 3-6, 2015

Voltec Battery Design and

Manufacturing

Milind GandhiGeneral Motors Korea

Milind.Gandhi@gm.com

Introduction

• Fundamental part of Volt

• Concept to production in 2 years

• Global effort

• Mainz-Kastel, Germany

• Honeoye Falls, NY

• Warren, MI

• Three key disciplines

• Mechanical

• Electrical

• Chemical

Organization

Systems Engineering

Project Management

Purchasing

Manufacturing

Quality

Heat Transfer

Electronics

Controls

High Voltage Wiring

Cells

Modules/ sections

Electrical hardware

Electronics

Structure

RESS Integration Team System Integration Team

Organization

• Non-standard development process

• Time-compressed

• Five iterations

Lithium Ion Cell

• Three purposes• Stores electrical energy

• Provide energy to vehicle

• Provide power for propulsion

• Design

• Prismatic pouch

• Most efficient in mass/volume for our application

• Construction• Aluminum positive terminal

• Nickel-plated copper negative terminal

• Terminals on same end

• Laminate aluminum packaging

• Positive and negative electrode films

• Electrolyte

• Separator film

Lithium Ion Cell

• Development

• Millions of hours of testing to guarantee performance

• UN3480 compliant (Transport of Li+ cells)

• Compatible with coolant

Modules

• 18- or 36-cell

• End plates

• Thermistor

• Cooling fins

• Repeating frames

• Interconnect board

36

18

Sections

Comprised of multiple modules

• Structural end caps

• Hose bibs each end

• Molded plastic cover

• Metal strap

• Tie rods (4)

Conditioning

• 50/50 de-ionized water/Glycol mix

• 1.8kW heater internal to pack

• External chiller

• Silicone hose connections

Conditioning

• Cooling fin

• Between every pair of cells

• Inlet and outlet ports

• Mylar backing

• Cooling channels

• Pressure loss across fin

>> manifold pressure

• Enables uniform flow

Mechanical Construction

Pack Summary

Power Distribution

• Requirements

• 360V DC nominal

• Peak current of 400A

• Robust

• Safe

High Voltage Architecture

• At module level

• 3 parallel cells in a group

• 1 group welded to ICB channels

• 6 or 12 series groups per ICB

• Plated, solid copper bus bars

High Voltage Architecture

At section level

• Section 1

• One 6-group module

• Two 12-group modules

• Section 2

• Two 12-group modules

• Section 3

• One 6-group module

• Three 12-group modules

High Voltage Architecture

At pack level

• Section-to-section bus bars

• Formed

• Multiple copper strips

• Protective insulation

• 6mm hole for termination

• Current sensor

Service disconnect

• Main fuse for pack

• Removed to service pack

• 350A rating

• Safe shutdown of HV bus

• Primary latch disengagement signals control system to disconnect HV bu

s from vehicle

• Secondary latch opens HV circuit in pack

High Voltage Architecture

High Voltage Architecture

Bulkhead/battery disconnect unit

• Interface to vehicle

• Safe switching of pack energy

• Pre-charge of HV bus

• Propulsion

• Charging

• Charging components

• Contactors

• Fuse

• Protects charging circuit

• Accessible without removing pack

• Pack heater

• 1800W design powered by HV bus

• FET-controlled

Low Voltage Architecture

High Voltage interlock

• Two circuits in vehicle route through pack

• Charger connection

• Auxiliary power connection

• Routing

• Through fuse cover

• Through MSD

Low Voltage Architecture

Measurements

• Thermistors

• Direct to cell

• Read by module

• Current Sensing

• Hall effect sensor

• Positive/negative current

• Fine/coarse signals

Electronics

Voltage Temperature Sub Module (VTSM)

• 4 per pack

• Connections to:

• Cell (voltage)

• Thermistors

• Cell overvoltage signal

• HV energy management network

• Dissipative cell-balancing

• Diagnostics communicated to battery network

Electronics

Voltage Current Temperature Module (VITM)

• Monitors

• Overall pack voltage

• Pack current

• Coolant inlet temperature

• Coolant outlet temperature

• Electrical isolation of HV bus to vehicle chassis

• Communicates

• Receives information from VTSMs

• Sends diagnostic information to external controllers on two separate networ

ks

Manufacturing Systems

Requires balance of speed and precision

• Upstream processes require high speeds

• Relatively low volume of packs

Manufacturing Systems

Three areas of assembly

• 1) Section subassembly• Quality checks

• Cell processing and orientation

• Component assembly

• 2) Section final assembly• ICBs installed

• Tabs welded to ICBs

• HV connections

• More quality checks

• 3) Pack main line• Sections assembled to tray

• Bus bars and wiring installed

• Hoses installed/clamped

• Electrical tests

• Cover installation

• Final inspection

Conclusions

• Requirements established early

• Iterative test and development

• Manufacturing strategy matches product requirements

• Fully validated