Status update

Posted on April 22, 2008


It’s been a long time since my last post, so some people are asking if I’m giving up or something… nope, nothing could be further from the truth. 🙂

For practical reasons, I’m working on several fronts at the same time, and this has prevented me from producing any concrete results. Let’s see…

  1. On the modelling/scripting side, I’m currently working on a way to break the motor models into interchangeable parts. This would allow me to run many different combinations of motor parts and find the best one for a specific real-world case. The intention is to be able to define the physical constraints, press a button, and get out a final result saying “the best motor design is like this, it will have such peak power and such peak torque”. Eventually I may even add “weight”, “volume”, and “price” into the calculations. Wouldn’t that be sweet? 🙂
  2. In order to feed the modelling scripts with accurate information, I’m researching magnetic materials. The simulation results are extremely dependent upon accuracy of the material properties, so I can’t ignore this. It’s not too hard to find the magnetic curves for the common magnetic materials; however, it is almost impossible to get any data about non-standard materials, like for example magnetic composites (i.e. epoxy with iron powder). So I’m trying to use this circuit (designed by Jan van Loon and built by my pal NJay) to determine which materials are worth using and which are not. I’m trying to find a compromise between the price, accessibility, and magnetic quality of materials.
  3. On the motor control side, I’ve been educating myself. I see that there are just too many ways to control an electric motor these days. I’m trying to pick a reasonably good one, something that guarantees high efficiency but isn’t too complex or expensive to build. I still don’t know if I’m going to build the controller or buy one, but this kind of information is always useful even if you’re just buying. I’ve also built an experimental controller with an old laptop computer and an analog capture card, but that didn’t go very well (the card was damaged during the development of the device driver – and it wasn’t my software’s fault!! 🙂 ). So that platform won’t be joining this project any time soon. 😦
  4. On the requirements front, I’ve been aiming to get a clear picture of what exactly my “new” car will have to do. One important set of input data is the power required to keep the car moving at various usual speeds. Unfortunately, I couldn’t find on the web or manuals my car’s Aerodynamic Drag and Rolling Resistance coefficients to feed these calculations. So I followed an “Instructable” from that Njay found, that describes how to measure the Cd and Cr of any car. The problem is that finding a long, flat, trafficless road in the greater Lisbon area is simply impossible… but I’ve got some data now, and I’m going to crunch it.

I’m sure I forgot something, but you get the picture…