Magnet Magic

When I take a ride on my Electric Moped, I hop on, turn a key and go. Within seconds, I’m gliding around town free, if only for a moment, of whatever I’m bogged down with at that particular time. My travel, be it to and from work, the grocery store or the gym, has become on of the most relaxing parts of my day. Riding the moped is something that I look forward to and miss when I am out of town. It is a true source of pleasure. One of the main reasons I find the electric moped so exhilarating is because of its quiet nature. It’s not common to be so close to nature on a motor vehicle. I feel like Lance Armstrong just without the huge thighs and all of the training.

What makes my new found joy possible? One large part is the rear hub mounted brushless DC electric motor.  We have become so used to the status quo that sometimes it is difficult to think of a vehicle without an engine, especially for the consumer, but believe it or not there are different ways to propel a vehicle.

The electric motor is an interesting method of propulsion to replace the gas combustion engine because it is hardly new at all (a light and powerful battery that powers the motor has been the missing piece to the puzzle until recently). The electric motor dates all the way back to 1828 when Hungarian priest and scientist Ányos Jedlik built a motor using an electromagnet for the rotor and a commutator to achieve partial rotation. http://www.mpoweruk.com/history.htm These same components, albeit assembled in a more sophisticated manner, are still used in today’s modern electric motors.

The direct descendent of Mr. Jedlik’s earliest version is a brushed DC electric motor. Like all electric motors, the brushed motor uses magnetism to create motion. Positioned in the middle of stationary permanent magnets is an electromagnet on an axel. An electromagnet consists of a piece of metal tightly wrapped with a conductive metal, typically coper, that is hooked up to a power source (ie: a battery). The electromagnet on the axel (called the armature) has a north and south pole just like like the permanent magnet surrounding it. Due to the law of magnetism where opposites attract and likes repel, when the like poles face each other the electromagnet is repelled downward rotating the armature 180 degrees. Just when the magnets are about to reach equilibrium, the poles on the armature are reversed so the two repel each other continually creating a fluid 360 degree motion. This type of motor is referred to as “brushed” because  the armature (in this scenario called the rotor) itself moves inside the permanent magnets (in this scenario called the stator). http://electronics.howstuffworks.com/motor1.htm

Diagram of a Brushed DC Motor

Although brushed DC Motors are simple and inexpensive and therefore perfect for small applications (ie: toy motors), there are significant limitations preventing their usage in larger devices. With the advent of inexpensive computers and transistors, brushless DC motors became possible, the first of which was used in commercial application in 1962. In a brushless motor basically the same components are in play but the roles are simply reversed. The armature is still positioned in the middle of permanent magnets but in this case the armature is stationary (becoming the stator) and the permanent magnets rotate (becoming the rotor) around the center. The computer that controls a brushless motor (called the controller) changes the polarity of the poles on the armature repelling the permanent magnets on the rotor (outside). The speed of rotation varies depending on the speed at which the polarity is changed. http://en.wikipedia.org/wiki/Brushless_DC_electric_motor

The benefits of a brushless over a brushed motor are many. A few are listed below:

• Brushes wear out, so there are no brushes to replace
• Connections are controlled by a computer, not the brushes themselves, making it much quieter
• Can go much faster because speed is not limited by a mechanical brush
• Much easier to cool as the electromagnet is spread out over a larger space
• It can have a larger amount of poles

http://electronics.howstuffworks.com/brushless-motor.htm

Diagram of a Brushed DC Motor

Dissection of moped hub mounted brushless DC motor

Completed motors ready for hub hounting

Copper wiring in stationary armature

A Spin Around the EV Biz

Electric vehicles have been around for years already (see Who Killed the Electric Car for a full history) but due to a number of factors, that we have addressed in previous entries, the market is just now becoming mature to the point of acceptance. The future is being developed as we speak and lately it seems that every auto publication has a new concept, prototype, or in some cases production model to show. These new transport devices, while not affordable, are creative, beautiful, and groundbreaking. I want to show you a few on the blog.

Tesla Motors

The company that started it all! These guys have to be credited for turning out an actual all electric production vehicle that could reliably travel on the United States roadways. Certainly their were home built electric cars and motorcycles before the Tesla Roadster but they weren’t going over 100 miles per hour with a 200+ mile range.

The Tesla Roadster is beautiful and it should be for the base price of $108,000. This is $50,000 more than it’s gasoline counterpart, the Lotus Elise, a steep premium for electric! While I haven’t driven this car (yet), I have seen it. It’s much smaller in real life than it might appear in pictures.

Tesla Motors is not content to target the expensive sport car market, they want to tap into the luxury sedan market with the Tesla Model S. This is more affordable at $60,000, it’s more practical as well because it seats 7. Tesla is a company with a recent influx of investment. Toyota Motors announced a partnership with them to start additional manufacturing factories in California.

Brammo Enertia

Brammo, Inc has been around since 2008. I remember seeing the Enertia Electric Motorcycle when it first came out. As a motorcycle rider I was captivated by the claimed 62 MPH top speed and 42 mile range. This thing would have been perfect for my daily commute if only it was a little more reasonably priced, $8,000 is too much for what you get. These motorcycles are built in Oregon and sold through Brammo’s own online store as well as Best Buy. I’d love to ask someone how they like it but I’ve never seen one in the wild. Maybe I should ask this guy for a test ride. Business has to be reasonably good for them. One of our readers sent us a press release stating that the snowmobile, ATV, motorcycle company Polaris out of Minnesota just made a substantial investment.

Zenn Motor Company

Less you all think I’m merely posting dream cars and making comments I wanted to steer us in a more practical direction.

I saw this vehicle when it first came out. It’s part of the LSV – Low Speed Vehicle category of autos that receive special tax breaks from the government. One of my friends was looking for a cheap, electric commuter car a few months back and I attempted to point him in the direction of Zenn. However, it looks like the company is going through some turmoil and isn’t currently producing the little LSV seen above.

Car and Driver had a nice writeup in December, 2008 of this vehicle. I’ll summarize what they say if you don’t feel like reading the article. It’s slow, uncomfortable, expensive and just not real practical. 25mph, 2 seater, $18,000.

Yike Bike

I just added Tron Legacy to my Netflix queue and I’m wondering if the designers and inventors took some queues from the movie. As I recall this is what the future of transportation looked like in the Popular Mechanic magazines I read as a child, that and the flying cars I’m still waiting for. Oh well, at least Yike Bike delivered! Despite the rather goofy design I can see this thing having some real appeal, particularly in Europe where folding bikes are everywhere.

10 km range, 23 km top speed, and a 55 min charge time aren’t performance inspiring statistics but one could certainly keep up with regular bike traffic on a path. The Yike Bike also folds up and can be carried over the shoulder. I’m not putting these electric vehicles up in any particular order but I’ll give this a 8 for ingenuity only topped by the unicycle electric “bike” that I’ll save for later. Check out the NY Times for a little more in depth review.

Trek Bicycle

Known a long time for well engineered bicycles, Trek has decided to branch out into the e-bike world. They aren’t going at it alone though, instead choosing to rely on the Canadian company, BionX, to provide the conversion package. I wonder if Trek is developing their own system or if they don’t view an e-bike controller, battery and motor as core competencies. BionX offers a number of different motor and battery configurations to a handful of OEM companies including Trek, KTM, and Matra. BionX also sells the entire kit through dealers.

Trek is a little light on electronic specifics but BionX has 250 and 350 watt electric motors with 48V 9 amp batteries so I can only assume it has something similar. One notable feature is that squeezing the brake lever on the downhill turns the motor into a generator that recharges the battery. Pretty sophisticated technology for a bike!

Uno Cycle – Ben Gulak

I saved the best strangest for last. The picture makes it look like a unicycle but it actually has two wheels side by side. This engineering marvel was invented by one of our neighbor’s to the North, Ben Gulak. He’s a native of Canada and built the Uno cycle when he was 18. MIT took note and accepted him as a student. As an engineer myself I can appreciate the complexity of this transport being able to balance the rider Segway style but is it complexity for the sake of complexity or a viable form of transportation? If any system fails there is a high probability that the rider might end up taking a fall. With a traditional two wheeler at least one can hopefully coast his or her way to a safe stop.

Motorcycle Mojo provides some tech specs. 10 MPH, 3 hour continuous use before charge, and 17 minute fast charge time. What really struck me is that Ben designed the entire unit using Google Sketchup, free 3D software. I’ve used Google Sketchup in the past but never gave it any consideration for doing professional level engineering work.

I haven’t seen any of these zipping around the neighborhood yet, nor have I seen an official commercial website for the product so I can only assume it’s still being refined before Ben takes it to market.

Android ADK – Open Source Fun

Look around and you realize that most people have a smart phone. Where does the smart phone fit in with electric vehicles? Google is trying to answer that question with the release of the Android Open Accessory Development Kit (ADK). Take a look at the following link if you want to read all the technical goodness.

http://developer.android.com/guide/topics/usb/adk.html

The bottom-line is that it provides an interface between almost any electronic gadget and an android powered device. Imagine having your electric moped plugged into a charging station (or your home) and getting real time information sent to your phone about charging conditions. Eventually we might be able to provide a phone dock on the moped that facilitates charging your phone but also provides miles per hour, gps, etc.

From a service perspective the device is even better. We will be able to quickly diagnose problems with a simple android tablet and a database of diagnostic codes.

The best thing about this whole system is that it leverages technology that a lot of consumers already have. When you buy an automobile, the premium for an on-board computer and navigation package is quite high (often $2000 or more). The systems usually look good for the first year but rapidly become obsolete. Don’t believe me? Hop in a car from 2006 and see what the navigation computer looks like. Android devices will be continually updated and supported by Google and most people refresh their phones on a 2 year schedule, I’d wager more often than people upgrade vehicles. The open source (and free!) software will continuously evolve.

Here are some screenshots of applications developers have already put out to leverage Android in the vehicle.

The below image is of software called Torque. It monitors a bunch of stuff including:

• Horsepower
• Fault codes
• Send logging information to web or email CSV/KML for analysis via excel
• Heads up display / HUD
• GPS Speedo/Tracking
• Alarms (for example if your coolant temperature goes over 120C!)

This functionality could extend beyond a Flux electric moped. For instance, a college robotics team might be able to use Flux electric hub motors in their design and pair it to an android phone. This is a very simple and cost effective solution to a problem that at one point required a dedicated motor controller, GPS unit, on-board computer, bluetooth module, etc.

For now the software and hardware package are in their infancy so there are not a lot of good examples available. However, with any good technology, the growth will be fast. I suspect we will have many great ideas and concepts by Google’s developer conference next summer.