About the JMS 14e

2. Accumulator System: - Battery pack contains 288 Lithium Polymer cells - Nominal voltage rating of 280 Volts and a total capacity of 6.4 kWh - Capable of discharging at 50 C Electric Powertrain: - Two Emraxmotors mounted for rear wheel drive - On-board Regenerative braking system -Ground Fault detection system About the JMS 14e Suspension: - 65” wheelbase, track width: 48” front and 46” rear - Pushrod system front and rear - 4-way adjustable dampers - Driver Adjustable Anti-Roll - Carbon fiber wheels and linkages • Control Systems • Over 30 sensors and 2 microcontrollers • High reliability custom embedded software with failsafe systems

3. Team Structure

4. Formula Electric - Work Breakdown Structure

5. Level 1 – Block Diagram

6. High Voltage System • High Voltage System split into two major subsystems: • Tractive System: • 75 kW nominal power output • 85 kW peak power output • Safety and Shutdown System: • Monitors vehicle for possible faults from Ground Fault, Battery Management and others • If a problem is detected will disengage the Tractive System until operator action is taken • Completely removes positive and negative terminals from Tractive System in less than 15mS • Drops voltage of Tractive System to under 40V in less than 1s

7. Tractive System Details • Emrax Standard LC Motor • 75kW nominal power output • 2.68 kW/lb nominal output • ~98% efficiency • 3 Phase AC driven • Rinehart Motion Systems PM100DX • Programmable unit capable of providing current limiting as well as facilitating regenerative braking • Drive by wire enabled via CANbusnetwork • ~95% efficiency

8. Shutdown Circuit

9. Safety and Shutdown Circuit details • Two keyed switches, three emergency shutdown buttons and one crash sensor. • All must be on for Tractive System power • Shutdown Circuit accepts input from four devices to ensure nominal operation • Ground Fault Detector (GFD) monitors resistance between HV and LV ground which is tied to the chassis, with a 150kΩ fault condition. • Battery Management System monitors voltage, current and heat from batteries • Brake Over Travel switch engages if brake moves past nominal range • Brake Panic System engages if throttle becomes unresponsive and the driver brakes • All systems open AIRs that connect batteries to the Tractive System if a fault occurs • All systems will latch and hold fault states until operator intervention.

10. Accumulation System Haiyin - Lithium Polymer Cells • 6 Ah Capacity with 50 C Discharge • Each cell is capable of provided up to 300 A continuously!! • Two banks wired together in series, each bank has a 36s4p configuration. • Lightweight at only 170 g (0.0022 lbs) each. • One of the lightest cells out there. • We have a total of 288 cells in the car, weighing in at 108 pounds (49 kg) • This accounts for about 1/5th the weight of the entire car! • One of the highest specific energies (Weight vs. Energy) available.

11. Battery Management System (BMS) Elektromotus • To prevent fire and other mishaps, a battery management system is used. • Monitors the entire bank of 288 cells. • Real-time data logging of voltage and temperature each 4 cells in parallel during both charging and discharging. • Provides protection from over-voltage and over-current outside specified range. • This data will be provided to the team via Beaglebone.

12. Control System • Control of the car is a closed loop system in which throttle input from the drive is modified by various environmental factors to optimize desired outcome • Hardware: • Beagleboneperforms heavyweight sensor analysis • Beaglebone relays sensor data over CAN network • Beaglebone provides fallback system with direct lines to brakes and throttle. • Software: • Written directly in C for low latency operation • Provides simple digital filtering of sensor inputs and decision outputs based on data • Passes decision data and filtered input along to data acquisition module

13. Sensor Grid • Suspension Member Strain – Strain Gauges (2 per wheel) • Wheel Speed – Hall Effect • Shock Deflection – Potentiometers • Tire Temperature – Infrared Thermometers (3 per wheel) • Road Temperature – Infrared Thermometers • Cooling System Temperature – Thermistors (4) • Steering Wheel Position – Potentiometer • Brake Pedal Position – Potentiometer • Throttle Pedal Position – Potentiometer (3) • Brake Pressure – Hydraulic Pressure Transducer • Attitude/Heading – Gyro/Magneto/Accel • Battery Pack Current Draw –EM Current Sensor • Overall Battery Bank Voltage – Analog Indicators/BMS

14. Control System - Block Diagram

15. Software Architecture

16. Regenerative Braking • Designed to replace mechanical brakes in most braking situations • Supplements the mechanical brakes during hard braking. • Energy generated will be used to recharge the batteries, increasing the range and efficiency of the vehicle. • The lower use of the mechanical brakes will lead to less brake wear over time. • Giving ability to slow the car in the event of a mechanical brake failure.

17. Regenerative Braking – Block Diagram

18. Regenerative Braking – Test Procedure • To test the effectiveness of regenerative braking, the motor will set to a certain RPM and full braking will be then applied. - Battery current, voltage, recorded. From this data, we should be able to calculate: • Kinetic energy lost during the electric braking test from 65 mph to 0mph. • Electric energy gained during electric braking test from 65 mph to 0 mph. • Efficiency of converting kinetic to electric energy. • Braking torque during the mechanical and electric test.

19. Regenerative Braking – For the Future The main improvement to the system in the next years will be the change from rear wheel drive to all wheel drive. • This will allow for the use of regenerative braking without the current stability issues. • Electronic brake biasing • Improved efficiency in recovering energy during braking. • Increased stability during acceleration and turns.

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