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 V, $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: $ Total: $520

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  Negative feedback tends to compare actual voltage with desired voltage and seeks to reduce the difference Scaled down buck circuit Inductor100uH Capacitor330uF 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 ?