Design Article
Viewpoint: Tesla, design and the art of innovation
John Sanguinetti
7/24/2009 10:54 AM EDT
Focusing on the power train resulted in a manageable project for a small team of engineers. The battery was the primary focus since you need a lot of stored electricity to move a 2,700-pound car at sports car speeds over an acceptable distance between charges.
Here, Tesla managed to use existing electronics IP in a novel way.
The battery is composed of 6,831 standard 18650 lithium-ion cells (somewhat larger than a standard AA-size battery) used in most laptop batteries. These batteries have to be closely matched and kept in a tight temperature range, which dictated the physical design of the battery pack with a liquid cooling system.
Other standard automotive IP "" radiator and fans "" were used to implement the battery cooling system. Along with controlling electronics, a reliable 53 KW/h battery could be constructed from all those cells.
Matching the battery with an AC induction motor enhanced by Tesla Motors, and power electronics to convert the battery's 370 volt DC output to variable frequency AC, yielded a power train that could achieve the necessary performance goals.
As with most innovative new projects, an unexpected difficulty caused a significant slip in the schedule. The more or less standard two-speed transmission initially chosen wouldn't handle the torque of the electric motor, typically failing in the initial prototypes after about 10,000 miles.
Designing a new one-speed transmission delayed introduction of the Tesla by nearly a year. By modifying the power electronics to get more power to the motor, designers managed to achieve the desired acceleration using a single gear, greatly simplifying the transmission. As in most high-tech projects, a schedule slip due to one reason was used as an opportunity to improve other aspects of the car, and the result is a more refined vehicle.
The end result is the Tesla Roadster, a car with outstanding performance "" 0-60 in 3.9 seconds "" and good range "" 244 miles on a single charge, which can be done in as little as 3.5 hours. I recently heard someone ask another owner if the Tesla is as fast as advertised. His answer was the same as mine: "Yea, pretty much."
In some ways, the Tesla gives the impression of being an elaborate peripheral device. It is a car an electrical engineer can love.
Innovation and electronic design
The Tesla Roadster is a perfect example of an innovative product, but is there any relationship between it and electronic design? Tesla did not design any of their own semiconductors, so we can only look it as general inspiration for design innovation.
Tesla didn't go for incremental improvement, but its designers also did not try to reinvent the wheel. The project focused on a central part of the car, and let that drive the engineering effort. A significant amount of existing IP was reused in the Tesla design.
No amount of incremental improvement to an internal combustion engine would produce a zero-emission vehicle, so the designer made a technology leap where it was necessary.
In cars, as with electronic design, it has been observed by an unknown author: "You can't expect to meet the challenges of today with yesterday's tools and expect to be in business tomorrow."
The electronic design industry needs to remember examples like Tesla. When setting your sights on an ambitious goal, develop a well thought-out plan, embrace new technology with an acceptable level of maturity and put all your effort behind it. If you do, good things are bound to happen.
—John Sanguinetti is chief technology officer at
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msd1107
7/24/2009 4:00 PM EDT
The Tesla is an innovative vehicle, but innovation does not make it desirable from the point of view of society.
The Tesla consumes electric energy to move. There is no pollution at the destination, but there is high pollution at the source. The electric grid is overloaded at times and is converting from older high polluting forms of generation to newer lower polluting forms of generation. However, all low pollution sources of electricity are fully committedfor high priority house and industry useage for the forseeable future, leaving only highly polluting sources of electricity to propel the Tesla. THus the Tesla generate much more pollution than the corresponding gasoline powered vehicle.
Cars pay substantial federal and state taxes on the gasoline consumed. The Tesla evades its responsibility.
There is a downloadable spreadsheet at http://www.lotuselan.net/forums/elan-f15/updated-spreadsheets-t18445.html that allows the user to model the energy consumption of IC, EV, and PHEV vehicles and has much more information.
Running a vehicle on electric energy is not a good choice except in the most restricted environments. The energy density of even the advanced li-ion batteries in the Tesla is less than 1% of gasoline used in SI engines, which means the EV is never viable compared to a gasoline powered vehicle
So even though I am a Lotus owner, and the Tesla is derived from a Lotus, the Tesla is not suitable for wide use in society.
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lakehermit
7/27/2009 1:32 PM EDT
Tesla has invested millions of dollars in their innovative design. It has taken years to complete the R&D and bring a product to market. I believe all of Tesla's Intellectual Property is worthless.
For years the US Congress and courts have relentlessly chipped away at US law protecting innovation. The so called "Patent Reform" proposals are really nothing but Patent destruction. http://www.mfgpatentpolicy.org/home.html
The attacks by Congress and the US courts, including the Supreme Court, have made it impossible to effectively protect innovation like Tesla's from the prying eyes of IP thieves. I'll bet that within 2 years some unscrupulous copyist has a similar vehicle with the same copied technology available for half the price. Of course, without having paid for the R&D, they can afford to sell much cheaper and still make a handsome profit. Because the teeth are gone from US IP Law, Tesla won't be able to do a thing about the theft! Even worse, investors will look to this example and be very reluctant to invest in any other R&D effort in the US.
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stixoffire
7/28/2009 3:48 AM EDT
You make a note that 0-60 and 0-100 times favor a gasoline engine - I beg to differ an electric vehicle has maximum torque available at all times and therefore is much better at accelerating than a sluggish Gasoline engine that has to build up that torque through a transmission no less! It would seem that you are an over enthusiastic hyped up purchaser that failed to do all your research. Nice car but nothing new or innovative except to you. On Demand Fuel Cells - Water to Hydrogen to Water is the true innovation. The technology does exist!
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NRILLC
7/29/2009 1:52 PM EDT
Tesla has not spent a lot of time on this. They took a car, placed a battery pack behind the seat that costs $22,000 and when one goes bad the car is dead on the road. It limps to the side of the road for someone to tow it back and find the one that is dead and try to replace it. Not very cost effective at all. Too much money for this car. Lotus helped design the chassis so Tesla really didn't design this.
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timsim
7/30/2009 2:00 AM EDT
Great technology and R&D. How much did it cost besides two years late. All electrics need the parameters of the Tesla at price we can afford and doesn't look like a modern art project.
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JamesAndersonMerritt
8/2/2009 9:15 PM EDT
Tesla worked with Lotus, but made a lot of changes from the original design to suit the particular needs of their EV application (not to mention the tastes of various execs, including now-CEO and major investor Elon Musk). Tesla also worked with (or following in the footsteps of) AC Propulsion, but again made significant application-specific changes in the controller and elsewhere in the powertrain. And of course, the energy storage unit design, which harnesses the nearly 7000 individual LiIon cells, as well as the control software and its user interface, are all Tesla's.
The only reason this car was "late" was the same reason so many high-tech products have been "late": Perception. It is hard to strike out on a new, basically uncharted path and accurately predict what you will find and when your journey will end. At the beginning, enthusiasm is high and unrealistic expectations are raised. Back on the company blogs after they announced the Roadster and first predicted a ship date, I recommended that people recalibrate their expectations and have patience. Even with the inevitable delays and snafus, the Roadster shipped right about when I expected it would, maybe even a little sooner, given the ambition of their project. The point was not so much when it would ship, but that it would ship AT ALL in the current regulatory and economic climate for the auto industry, not to mention that it would be as pleasing to its owners as it turned out to be. That was a real accomplishment.
As far as the "remote pollution" charge, I find it bogus. Even when you count inefficiencies in power generation, transmission and charging, the Roadster still manages to get impressive mileage from the power-station fuel equivalent of 1 gallon of gasoline. In addition, more and more Roadster owners are installing their own solar panels, so as to be able to power their cars without net draw from the power grid and the polluting generation plants that feed into it. The Roadster doesn't care where it gets its electrons, and so is the ultimate "alternative fuel" vehicle. As the grid becomes cleaner, so will the net emissions of the Roadster and other EVs be reduced. In California, for example, a good portion of power delivered here comes from renewable or relatively low-polluting sources (e.g., hydro, solar, nuclear, and natural gas). Even power that comes from "dirty" sources can be cleaner than burning fuel in the vehicle's engine, because it is easier to scrub the output of a power plant's smokestack than the output of millions of tail pipes.
Most of the criticisms of the Roadster that I see today are charges that have been around for a long time and have been debunked for years. I would have expected commenters at "EE Times" to have been better informed and to have worked a little harder. If you look hard enough, you WILL find some valid engineering criticisms of the Roadster, but the kvetching here doesn't get close.
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JamesAndersonMerritt
8/2/2009 9:25 PM EDT
By the way, before anyone Googles me and jumps on my job title (believe me, some have in the past!), be aware that Workswright Software is a dba that I use for consulting and other projects. I only provided that because the stupid website wouldn't let me post a comment here without giving up a lot of information. I'm not trying to bamboozle anyone with an impressive title or affiliation. On the other hand, I know a lot about the unrealistic expectations and predictions attending high-tech product development from spending around 20 years in personal computer software engineering and support, including 10 years at Apple. Like many "graduates" of that company, I am doing different things today, but you never forget the lessons learned in such a crucible. That predisposed me to be a fan of Tesla from the start, and enabled me to cut them a fair amount of slack as they kept discarding unrealistic plans and predictions, yet kept pushing until they could ship something great.
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