NIATT Formula Electric Vehicle Powertrain Team
|Early Design Concept|
(Mechanical and Electrical Stopping System)
|Duration||Fall 2013 - Spring 2014|
Our purpose is to design mechanical and electrical braking for the new all-electric formula electric vehicle. The vehicle will be powered by in-hub linear induction motors. We are also designing motor housing, bearings, and an apparatus for testing. Ultimately the vehicle will compete in the Society of Automotive Engineers (SAE) all-electric vehicle competition.
Jaz Veach, a graduate student in the electrical engineering department is currently designing in hub motors for an all electric vehicle. The motors will be using linear induction motors as the wheel as well as the drive system which will be more efficient than a conventional internal combustion engine and drivetrain. Because the only rotating part of the motor is the rim, braking and connecting the motor to the car is difficult.
The electrical engineers are designing and building regenerative braking system as well as a battery charging system for the vehicle. The mechanical engineers building a motor housing, a mechanical braking system, and a stand to be used to test the motor and braking.
Linear Induction Motor (LIM):
- Rotating rim/rotor
- Static center/stator made of laminated metal plates with fins and wire coils wrapped around the fins
- Projected operating speed (straight line) - 35mph
- Projected power - 25hp
- Inside diameter - 4 inches
- Outside diameter - 9 inches
- Width - 4 inches
- Mechanical Braking
- The vehicle must be able to stop the vehicle in a reasonable amount of time
- The brakes must be able to lock up the wheels at speeds of ~40mph in competition
- Regenerative Charging
- The motors should be able to act as generators to save energy as the vehicle is braked electrically
- The system should be able to charge the batteries from 120 VAC 240 VAC and 500 VDC
- Wheel Attachments
- The wheel attachments should be able to take the force of the motors as well as the weight of the vehicle
- The wheel attachments should be easy to attach to a test apparatus as well as the suspension of the vehicle
- The rim of the wheel should be removable to accommodate for wet or dry tires at competition
- The wheel/motor assembly should be as light as possible and less than 40lb
- The wheel attachments must be able to serve as a bracket for the brakes
- Test Apparatus
- The test apparatus should be able to simulate the LIM
- The test apparatus should be able to accurately measure braking forces under reasonable loads
- The test apparatus must be able to handle loads without failing
- The bearings must be able to keep a clearance between the stator and the rotor of the LIM
- The bearings must be able to hold the rotor on the stator given side to side dynamic motion
- The bearings must be able to handle ~1000lb static loading
Design concepts to fit the objectives:
The Final Product
Our final deliverables were a rapid charger for the existing battery system, motor stand and housing, and mechanical braking. These are all pieces that are required to test the in-hub motors when they are built (summer 2014).
Full Assembly Model
The motor will go where the wood cylinder is, and the small shaft will connect to a water-brake dynamometer. This video shows us proving the stand and braking capabilities with a DC motor connected to the small shaft.