Mid-Term Presentation

Come stop by Temple University on Tuesday, October 19th. We'll be presenting for our mid-term review at 12:50PM in room 217A of the Howdard Gittis Student Center (SAC). Everyone is welcome, and the presentation is a short ten minutes. We'd love to see you there!

HEATT

Senior Design 2010 - 2011

Welcome Back!

The Fall 2010 semester at Temple University has begun bringing a new senior design team to work on the Audi TT. We'd like to introduce ourselves briefly:

Stephen Barrett - TU Senior - Mechanical Engineer

Jonathan Childs - TU Senior - Mechanical Engineer

Dean Cun - TU Senior - Mechanical Engineer

Emmy Messina - TU Senior - Electrical Engineer

We will be updating this blog regularly with our challenges, successes, troubles and overall progress on the Audi TT. We feel privileged to be a continuing part of this project and we are excited to get our hands dirty.

Stay tuned!

First road test

It is a success!

The weather was horrible. It rained and poured on the first day of testing, but by the second day, it cleared up and was beautiful.

On the first day, we took it for a spin and got it up to 25 mph. We didn't want to push it too far too soon especially with the way the weather was behaving.

On the second day, we took it up to about 40mph in a parking lot and it behaved exactly like a normal car except there were no engine noises and turning on the vehicle was eerily quiet.

Here is more of a press shot showing off Temple. The car looks so sexy and beautiful that it is hard not to see this as the future of passenger vehicles especially when the performance and handling is on par with a normal vehicle.

Here is a short video of the initial testing. We took it out for about 5 hours of testing and probably drove about 20 miles at varying speeds.

Prepping the vehicle for the first road test

We are getting close to testing the vehicle and this means we have to start putting it back together, stop debugging it for a couple of days, and finalize what we have at this point.

This is what the car looked like two days before it got moved out of our lab and into road testing.

We had to put the lights back on the vehicle and wire them up in addition to writing controls to engage the back reverse and brake lights when they would engage on a normal vehicle.

This is what it looked like the morning of the road test.

We tried to pick a good day weather wise for the test, but the weather took a turn for the worst as we began to take the vehicle out of our lab and onto the road.

Soundproofing the vehicle

One of the biggest advantages with electric vehicles and hybrids, is the lack of engine noise when the vehicle is not moving or moving at low speeds. Soundproofing was added to the rear of the passenger cabin to help reduce the noise created through road noise and the IC generator. This was achieved by building a sound wall, adding a sound box around the IC engine, and through modifying the muffler of the IC engine.

This is a view of the Geo Metro muffler that was adapted to fit the IC engine we have.

This shows the sound wall and a view of the rear of the vehicle.

Testing the Motor

After wiring the batteries, we connected the 3 phase AC motor cable to the motor controller connection and the power and ground of the batteries to the controller cables. Below is a picture of the 3 phase cable connected to the controller.


The controller also requires 12V DC to operate, so for our first test we simply just hooked up a lead acid battery from our lab. The tricky part at this point was connecting all the pins, or leads from the throttle (potential meter), motor controller, and starter switch (having options of reverse, start/neutral, and drive). This took some time to figure out, but after using the manual and connecting our laptop to the controller to troubleshoot, we managed to figure out the problem.

After working together, we finally had all systems go. We are ready to push the throttle and see our motor move. Mind you we were all very excited and extremely nervous because this is the first time we will see our design in action after working on the project since June 2009. Take a look below!

Wiring the Batteries

There are 90 lithium iron phosphate batteries wired in series. Each battery is roughly 3.2V which gives a total of 300 Volts. This took about a day and a half. With all the wiring preparation for the BMS, probably about a week. We covered each terminal with duct tape so we wouldn't accidentally short a battery or shock ourselves. Yea, we played it safe.

A close up shot of a terminal. The wire is connecting the bottom layer to the top. The large red wire is high gauge rated for the large amount of current and voltage, while the skinny orange wires are connected to each battery node to read voltage for the BMS, which is not yet connected to the white inserts.

Jordan admiring the awesome power and thankful he wasn't shocked.

Another shot of the wired batteries. Two layers, 90 batteries, 300V, ready to light the tires!

Battery Management System

The battery management system's (BMS) job is to regulate how much the batteries charge and discharge evenly and within safe limits. Batteries cannot be over charged nor can they be discharged too low or they can become damaged. Also, lithium ion phosphate batteries do not all charge evenly, meaning if one charges faster than another it has the potential to reach maximum charge and beyond before the other batteries.

The BMS, designed primarily by Luis Breziner, is a circuit board whose job is to relay information back to the CPU, a National Instruments cRIO. The circuit boards will relay the voltage of the batteries they are assigned to back to the CPU, and if batteries are charging too fast compared to the average rate, the CPU will shunt them-- a resistor is turned on to limit the amount of current supplying the battery with voltage. This in effect keeps all the batteries charging at an equilibrium rate giving us control to limit how much they are charged.

The BMS gives us control over charging the batteries and also discharging. Since each board can read each battery's voltage, the CPU can determine how low each battery has dropped in charge, or voltage, and cut off the system before the batteries discharge beyond repair. Below is the process we took to assemble the boards once Luis finalized his design.

Luis pumped his BMS design is finished. He sent away for the chips and boards himself. Once they come, we have tons of work in store.

The material arrives and we have work. This is a group shot of us assembling the boards.

Pete and Jordan working.


Some parts needed a helping hand to solder.

Christophe and Pete finalizing the boards.

Above is about 90 BMS units, 5 to a board, 18 boards total.

Another look

Close up look.


Luis running a test on NI LabVIEW.


A board being tested. We hooked up and tested each board.


A close up look of the connections.




Luis Testing the boards, hard work pays off.

Seats

Two of the big considerations in this project are weight and safety. Less weight means the car is more efficient, so we tried to shave the weight as much as possible. One of the easiest ways to do this is to replace the heavy stock seats (with seat warmers and airbags) that weighed about 50 pounds each with low weight racing seats that are about half of the weight and weigh only 50 pounds for the pair. This also helps to improve the safety of the vehicle because we kept practically none of the stock safety features and even made the car more unsafe through body modifications.

With that being said, the new seats look unbelievably awesome and fit nicely. We went with the Corbeau A4 reclining seats and a four point harness system.


This is a view from the rear of the vehicle.


How can you argue that these seats don't look good?



This is how the vehicle looks so far...

Brakes and Pedals

When we were removing components from the car shortly after we got it, we took off the front and rear subframes and corresponding brake lines. Some of them got lost and we also cut a bunch when we were cutting the frame for the motor mounts. On top of that, the original brake rotors and pads were incredibly worn down and needed to be replaced. We just recently replaced pads and reran the brake lines and bled the brakes with new fluid. Now we can stop the car, which is always a good thing to be able to do.

On another note, we had to create our own pedal to integrate with the motor controller. We decided on a single degree of freedom design that allows the pedal to travel without hitting the brake all while properly engaging the throttle controller supplied with the motor.


The accelerator pedal is hinged at the bottom and moves a rod that is attached to the throttle controller on the left.


We also had to make it look interesting.

Generator

We just installed the generator this week. It is a standard generator that would be used on a job site by a contractor. It can produce 10kW continuously and is just perfect for our needs. When we were looking at generators every model we found above ~5kW seemed way too big for our space because the dimensions were always given with the frame included. To get an accurate measurement, we had to call the factory and have them measure the unit directly. Once we knew how big it was, we ordered it knowing we had about 2 inches of side to side play and we had to cut out the rear bumper area.


This shows the vertical and horizontal supports for the generator to sit on. We made the design modular to allow the generator to be removed without any specialized equipment.


Here it is! It fit almost too perfectly. If it was any bigger it would not fit.


We got it to fit without entering into the plastic bumper area.


One final view from above.