Download Multi-Cell Lithium-Ion Battery Management System

For Electric Vehicle
Team Members
•Pramit Tamrakar- Electrical Engineering
•Jimmy Skadal- Electrical Engineering
•Hao Wang- Electrical Engineering
•Matthew Schulte- Electrical Engineering
Adviser
•Ayman Fayed
Client
•Adan Cervantes- Element One Systems
Team-id- SdMay11-04
Problem Statement

Develop an efficient and safe system for
charging and monitoring of multi-cell
series batteries in Electric Vehicles
using AC to DC Switching Power
Converters.
System Specifications
Functional Requirement

Li-Ion Battery Management (90 cells in
series)
 Constant-Current Constant-Voltage (CCCV)
charging procedure
 Battery Gauging
 Temperature Monitoring
 Overcharge Protection

Achieve 100 miles range per charge
Non-Functional Requirements
Generating a 324 VDC power bus from a
120V VAC outlet
 Ensuring safety

Constraints and Technology considerations


Constraints: The charging process
Technology:
 Three Stages Charging Technology
 Pre - charge Constant Current stage
 Constant Current charging stage
 Constant voltage charging stage
 Voltage converter
 Boost converter circuit
 MSP430 Microcontroller


Constraints: High voltage control
Technology:

Scaling down by a factor about 4
(90 series cells to 24 series cells)
Market Survey
Commercially available switching
mode power supply for electric
vehicles is offered by Brusa.
 The NLG5 provides a high voltage
power source from a 120V or
240V wall outlet.
 Cost: over $2,000
 Brusa does not have a Battery
Management Systems.

NLG503-light battery charger.
1.6 kW 200-540V, $2,145
Risk


Electric Shock: The risk of electric shock is possible when
working with a charging system.
System Component Damage: As power is being applied and
the charging system is running, the risk of overheating,
voltage/current spikes, and incorrect connections are possible.
Mitigation



Testing and Simulation: To prevent component damage and
ensure proper design, the system will be modeled to test for
expected results.
Lower Volt System: With the 42V – 86.4V scaled down
system, the risk a shock is reduced.
Smart and Safe: By knowing how to be safe and building the
system with human/component safety in mind will aid in
avoiding risk.
Project Plan Milestones and Schedule
Cost Breakdown
Total:
$520
Total: $2120.00
System Design
Functional Decomposition (Hardware)
Functional Decomposition (Software)
Large Scale design
Small Scale Design
UCC28019AEVM Boost Circuit

Will supply the needed maximum 324
volts to the buck circuit for the large
scale charger

350 W Power Factor Correction (PFC)
boost converter

390 VDC regulated output

0.9 A of load current

Advanced fault protection
Buck circuit and Feedback Loop

The buck circuit will take the
voltage generated by the
boost buck down to cells

The negative feedback loop
Scaled down buck circuit

Negative feedback tends to
compare actual voltage with desired
voltage and seeks to reduce the
difference
Inductor
100uH
Capacitor
330uF
Value of components
Battery Management System



Will use TI’s processor bq76PL536EVM-3 and Aardvark USB-SPI
adaptor
EVM-3 will monitor, balance and charge 24 cells in series
Will use Aardvark to gather the packet of
information and display in the PC using
using Evaluation software

Implementation of the bq76pl536 with 24 series
cells
Software Technology Platform
• Use Ti’s Evaluation software to monitor the status of batteries
Test Plan

Subsystem test:
• Boost Converter
• System DC supply
• Buck Converter with MSP430 Launch Pad
• All necessary voltages and currents with PWM
• Battery Management System communication
• USB-SPI Processing GUI (PC)
• Ability to control feedback loop from MSP430 to buck

Integration Test (scaled down):
• 24 cell charge/discharge
• 48V-86.4V CC (up to 3A), 86.4V CV until 0.3A
Prototype Implementations &
Results



Coding for the MSP430 PWM output and ADC has been
completed
Basic resistor divider input has been implemented to
changed the PWM duty cycle
Components for the buck converter have been sourced
Current Project Status
Task Distribution

System Design
 Buck Converter-Matt, Hao
 Boost Converter-Matt, Jimmy
 Battery Management System-Pramit, Matt
Jimmy, Hao
Plan for Next Semester
Obtain parts and evaluation module from
TI
 Use what we can to quickly expand the
scaled down version.

• Series PCB
• Use single evaluation module
Implement the buck converter.
 Implement communication between the
evaluation module and the MSP430
 Display charging information with a pc

Questions ?