Formula SAE Electric

[uG]

Dear FSAE colleagues,

Since Formula SAE is starting to allow electric vehicles, I feel that this forum seriously lacks content on how to design electric cars!

As a start, I'm offering you folks to take a look at what my team an I did in 2012: our first car, and our first electric car. Our car is not necessarily an example to follow, but, is a start: it successfully passed through FSG 2012's electrical and mechanical scrutineering processes.

We decided to publish our components designs under open source licences in order to:
• Allow people to collaborate on the design of better and safer electric cars
• Extend the learning experience of Formula Student/SAE Electric
• In the long term, reduce GHGs.

Only a fraction of the car is published, yet. More will come. Interested ones can follow us on our website or facebook page. You can expect the facebook page to be more frequently updated though.

Here are links that could interest you guys.

- BMS (Battery Management System)
- TSAL (Tractive System Active Light)
- Traction Controller
- Business Plan Executive Summary
- Design Report
- EST (Electrical Safety Form)
- SEF (Structural Equivalency Form)
- Safety Responsible Qualification
- Video Status Report
- FMEA (Failure Modes and Effects Analysis)

If you use these documents/pieces of software/hardware while designing your car, please, let us know by email (info at felectrique.polymtl.ca), and publish your (improved) design, on your website. It’s, in our opinion, the basics of Open Source & Hardware, and a great way to improve technology.

If you take the time to take a look on the SVN repositories, you'll find out that the code is mostly commented in French, since we are a French Canadian team. It's gonna be translated over time.

Courage at always making better cars!

Hugues Marceau
Formule Électrique de Polytechnique Montréal

[Tilman]

Heyho,

i really appreciate the release of those documents/schematics/parts

I am not involved in building an E-car but I think that these documents are a very good start for first year electric teams.

By the way, I looked into some of the projects and saw that you are using an optocoupler in your tractive system active light controller ... I once read the FSE 2012 rules and I remeber that on PCBs which are connected to the low and the high voltage system there has to be a distance of some 10 millimeters between the two voltage systems. Is the optocoupler that wide to fulfill the rule or is there an exception for the parts where information is passed from one voltage system to the other?

[TMichaels]

You are wrong Tilman
The FSE2012 rules never contained a rule prescribing a certain distance on PCBs.

[Ben K]

Originally posted by hug:
Dear FSAE colleagues,

Since Formula SAE is starting to allow electric vehicles, I feel that this forum seriously lacks content on how to design electric cars!

As a start, I'm offering you folks to take a look at what my team an I did in 2012: our first car, and our first electric car. Our car is not necessarily an example to follow, but, is a start: it successfully passed through FSG 2012's electrical and mechanical scrutineering processes.

We decided to publish our components designs under open source licences in order to:
• Allow people to collaborate on the design of better and safer electric cars
• Extend the learning experience of Formula Student/SAE Electric
• In the long term, reduce GHGs.

Only a fraction of the car is published, yet. More will come. Interested ones can follow us on our website or facebook page. You can expect the facebook page to be more frequently updated though.

Here are links that could interest you guys.

- BMS (Battery Management System)
- TSAL (Tractive System Active Light)
- Traction Controller
- Business Plan Executive Summary
- Design Report
- EST (Electrical Safety Form)
- SEF (Structural Equivalency Form)
- Safety Responsible Qualification
- Video Status Report
- FMEA (Failure Modes and Effects Analysis)

If you use these documents/pieces of software/hardware while designing your car, please, let us know by email (info at felectrique.polymtl.ca), and publish your (improved) design, on your website. It’s, in our opinion, the basics of Open Source & Hardware, and a great way to improve technology.

If you take the time to take a look on the SVN repositories, you'll find out that the code is mostly commented in French, since we are a French Canadian team. It's gonna be translated over time.

Courage at always making better cars!

Hugues Marceau
Formule Électrique de Polytechnique Montréal

This is fantastic. I am wondering if we should request a new section to the forum for the electric vehicles?

Ben

[Warpspeed]

Tilman, electrical safety should concern us all.

The basic philosophy is, a plain flat surface can, over time, build up a layer of conductive dirt, salts, or moisture and create an electrical leakage path, which may gradually present a future safety hazard, or cause an electronic failure.

Hence the requirement for a fairly large physical separation of high voltage parts mounted directly onto a circuit board.

Where there is a physical air gap, the conditions are very different.
Moisture or dirt cannot so easily bridge the gap to create a leakage path, so distances can be greatly reduced without compromising safety.

One common scheme is to mill a narrow slot into a circuit board directly beneath a high voltage opto isolator. Another is to run a ground track between high and low voltage sections of circuitry.

If the whole thing is sensibly thought through, the high voltage parts protected, and kept clean, designing something that is inherently electrically safe and reliable, should not be that difficult.

[Tilman]

Originally posted by TMichaels:
You are wrong Tilman
The FSE2012 rules never contained a rule prescribing a certain distance on PCBs.

OK Mr. Precise,

it's in the 2013 FSAE rules, EV 4.1.5 and EV 4.1.7. They define minimum distances between the two systems. Again: An optocoupler is not large enough to keep these distances. Even if you measure the distance between the IC's legs the distance between the LED and the phototransistor inside will be very small. Does this mean that the team has to use fibre optical cable to pass information from one voltage system to the other?

Thanks Tony, I was not aware of the ground track and milled slot trick.

[Warpspeed]

Opto isolators all have a solid internal transparent barrier that provides the basic high voltage isolation rating.

An open air path will break down much more readily than a solid piece of glass, plastic, or silicon rubber.

The problem with opto isolators mounted on circuit boards is not so much high voltage flash over (at least not for us !) But troublesome electrical leakage caused by a buildup of crud or condensation on the board.

If all this really worries you, how about using a really wide optical fork as a simple opto isolator ?
These have very wide pin separation, a huge open air path between Led and phototransistor, and if it has a Schmidt trigger buffered output stage, they can also be quite fast.

[TMichaels]

You may also get away with coating the PCB as also shown in the respective table in EV4.1.7
There are quite some electrically insulating coatings available where the PCB still can be soldered, if this is needed.

[Tilman]

Thanks for your answers.

I am not building an E-car, I was just interested.