Transcript LithiumIon Battery Char

For Electric Vehicle
Team Members
• Pramit Tamrakar - EE
• Jimmy Skadal - EE
• Hao Wang - EE
• Matthew Schulte - EE
• William Zimmerman - EE
Advisor
•Ayman Fayed
Client
•Adan Cervantes- Element One Systems
Team-id- SdMay11-04
Problem Statement
To develop an efficient and safe system for charging and monitoring of multicell series batteries in Electric Vehicles by using AC to DC converters.

Charging Goal
18 Series Batteries, 2.3 Ah each
 45 minute CCCV charge

System Specifications
CCCV Charging sequence for
Lithium-Ion Batteries
Project Goals and System Diagram
Design a Lithium Ion Battery Charger that is capable of safely charging 16
parallel packs of 90 cells in series (Large Scale System).
 Successfully build an 18 cell charger that is capable of monitoring and balancing
the cells. (Small Scale System)

Full Scale System Diagram
Project Plan

Acquire boards/parts from TI
 Use built in capabilities to daisy chain the
boards

Close the feedback loop
 Connect the boost converter, buck
converter, test board, current sensing
resistor, amplifier, and aardvark software to
ensure proper charging
Test & Prototype the small scales design
 Hardware Cost

 $2120.00
Project Design



BQ76PL536EVM-3
•
Battery management
system
•
Track the voltage and temp.
for all batteries
MSP430 with buck circuit
•
Generate All necessary
voltages and currents with
PWM
•
Negative feed-back loop
Aardvark Interface
•
Small Scaled System Diagram
To display the status of the
charging system
Project Design Issue

Daisy-chained EVMs


Proved the ability to hook together multiple EVMs.
System Signal Components
 Ordered MOSFET drivers and power resistor to operate our buck
converter


Ordered components to amplify small signals produced by the microcontroller
SPI Communication
 Programming MSP 430 in order to build SPI communication between
micro-controller and EVMs
Buck Circuit Implementation and Testing

The buck circuit will take a voltage given by
some supply and decrease the value as
needed.

There will be a negative feedback loop in
the system so the Buck can accurately
output the desired current or voltage.
Tested Buck Circuit
with PSpice by
changing the input
PWM and observing
the output.
Value of components for
scaled down buck circuit
Inductor
100uH
Capacitor
330uF
Buck Testing



Variac wall transformer (rectified) to DC
Input DC from Variac at 65V
Buck output expectations:
 32.4V-64.6V
 Max 3A
 Power Resistor Test Load
Buck
Testing
Schematic
EVM- Testing Plan

TI’s processor bq76PL536EVM-3 and
Aardvark USB-SPI adaptor

Aardvark driver will be installed in a laptop
before installing the TI evaluation software

Tested the EVM board with 12-26 VDC
Power Supply

Plan to configure the EVM with cells

Use the TI’s WinGUI user interface
software to monitor the status of the cell
EVM- Safety

The battery connections should be made secure, a loose
connection may result in device destruction.

The ideal connection sequence is from pin P1.1 to pin 3.7 in
order to avoid the any connection error

The Absolute Maximum voltage per IC is 36V

Caution must be taken when using the EVM as part of a
stack , where lethal voltages may be present
MSP430 Programming


Code Composer Studio v4
Tested modules:
 High frequency clock
 ADC
 Timer/PWM
 Basic feedback
 Low Power Mode

Unfinished:
 SPI communication
Semester Schedule
Questions ?