CSU Formula SAE

Ram Racing 2016

Background/History

Colligate Electric Racecar design competition

Ram Racing was established in 1996

2nd iteration of Formula SAE Electric

Competition

Static events

Design Judging, Cost Report, Project Presentation, Technical Inspection

Dynamic events

Acceleration, Skid pad, Autocross, and Endurance

Problem Statement

Design all systems independently

May have professional advice but all designs must be Student drafted

Acquire data for future teams

Battery temperature characteristics, discharge time, and charge time

Forces acting on the car and driver

Optimum gears ratios for each event

Objectives and Constraints

All designs are acceptable according to Formula SAE requirements 2015-2016

http://students.sae.org/cds/formulaseries/rules/2015-16_fsae_rules.pdf

Pass technical inspection

System should lend itself to evolution design

Remain within budget

Fundraising, Donations, Sponsorships

Design Summary

Design Control Circuits

Reliable, Simple, and easily maintained

Years after wont have to worry about these circuits

Design Battery

300VDC, Lithium Cobalt Oxide

10Ah at 15C discharge

Implement Real-time Microcontroller

CAN communication

Data allocation

Mechanical Design Summery

Spaceframe chassis

EMRAX 207 motor connected to differential via chain

Interchangeable rear sprockets to vary gear ratios

Batteries cooled by forced airflow from sidepods and exhaust fans (if needed)

Key Improvements

Improved rear suspension

New battery case

New motor mount

Redesigned sidepods

Design Decisions

Safety and Control Circuits

12VDC system, in series switches and relays controlled by parallel systems (IMD, BMS, etc…)

Ladder logic

Robust, reliable, simple, and proven

12 VDC coil, 10 A contact, small (15mm cubes), automotive grade

Real time Microcontroller

Atmel 32-bit AVR UC3 AT32UC3C0512 144 pin

5VDC-12VDC power input

Dual CAN Communications, Local Network Interfaces

One 4-channel PWM controller, one 16-channel ADC, two 12-bit DAC, 123 GPIO pins

Atmel studio IDE, C programming

http://www.rlocman.ru/i/Image/2011/03/16/AT32UC3C-EK.JPG

Design Decisions

CAN Protocols Encoder protocols

Accelerator 10% Accuracy, voted output, pass to motor control

Brake plausibility Accelerator is not outputting while brakes are applied

Data logging Speeds

G-forces

Battery states

Motor states

Pedal positions

https://upload.wikimedia.org/wikipedia/commons/thumb/5/5e/CAN-Bus-frame_in_base_format_without_stuffbits.svg/709px-CAN-Bus-frame_in_base_format_without_stuffbits.svg.png

Design Decisions

High voltage Controller

Rinehart PM-100DX

Used From 2014-’15

Future Evolutions May Not Use

100-360VDC IN, 300VAC OUT, 250ADC Continuous, 350ADC P-P

Not a Choice of the Present Team (Cost Consideration)

Motor

EMRAX 207 (208)

300VAC, 140 Nm (103 ft-lb), 160ARMS, Weight 20.7 lbs

Chosen for Cost, Size, Weight, Standardization

http://www.rinehartmotion.com/standard.html

http://estacars.com/wp-content/uploads/2014/11/emrax_228_oct_04.jpg

Design Decisions

Battery cells Melasta SLPB9664155

3.7 VDC nominal, 10Ah

15C (150A) continuous discharge rate, 20C (200A) max.

72 series configuration for 300VDC

Battery Management System Orion controller

108 cell voltage sensors

Cell voltage balancing

Dual CAN Communications

Thermistor Expansion Module 80 temperature sensors

CAN bus communication

http://melastabattery.sell.everychina.com/

http://evolveelectrics.com/images/products/secondary/orion%20bms-1.png

Budget• Predicted Initial Budget• Simplified Budget

• Total Raised: $7,500• Account balance: $1,300• Need to raise: $6,500

At-risk Items and Mitigation Plan

Most At-Risk Components (Electrical)

Motor (Heating/Power), Battery(Heating), MSC (Component Failure)

Formula = (Rank/40)*R.O.O.* D

1, .6, .315 (Weighted Risk)

High Risk Due to High Occurrence

Not Indicative of Catastrophic Fault but working Limitations

Performance Impacted Mostly

ESA and FMEA have lead to realization of possible subsystem/battery failure

Validation (Design Evaluation, Prototype Evaluation)

Electrical Validation Benchtop testing

Test-to-Validate Approach

Test integrated vehicle circuit before installation

Functional Testing in Vehicle

Work-plan

Purchase the Orion Battery Management System

Bench-test circuits

Rolling chassis by 1/1

Assemble wiring harness on chassis

Battery complete by 2/1

Completed car for testing by 3/14

Test drive and collect data for future improvements

Complete tested car by E-days

Questions?

Logic Schematic and Diagram

Electrical FMEA

Mechanical FMEA