Interview with Prof. Andrew Frank, head of the UC Davis Challenge X entry, Team Fate
ABG: For 14 years UC Davis has been creating and demonstrating PHEVs. What would you say have been the most significant technological and cultural changes in relation to PHEVs in that time?
AF: The technology of computer controls, power electronics, and batteries have moved from being a good concept to being a much better concept that is now ready for "Prime Time."
ABG: What area of PHEV research and development do you feel is needed the most to get these vehicles onto our roads?
AF: High power electronic devices and batteries need to come down in price a little more. But everyone says if a firm order for 100,000 vehicles per year was placed the total cost of the car may be only 15 percent more than a conventional car. But you would get all the other benefits which would pay back your investment in less than a year and provide you with savings for the life of the car since the batteries will last 15 years and 150,000 miles.
ABG: You are planning to use 96 lithium-ion cells from LTC to become the battery pack for your Challenge X entry. What types of applications are these particular li-ion cells usually used in?
AF: The company GIAI makes batteries for the aerospace industry and have made these large batteries for hybrid bus applications in Germany.
The interview continues after the jump.
ABG: How has using li-ion batteries increased your vehicle's performance in comparison to using metal hydride or lead acid batteries?
AF: It has reduced the weight for a given electric range and it has also improved the performance since they are capable of delivering much more power. Li-ion batteries' charge efficiency is also better, so they can use electrons much more efficiently than metal hydride and are way beyond lead acid batteries. Their efficiency more than justifies their cost at this time and will be better in the future.
ABG: Is working with li-ion batteries significantly different to other battery technologies?
AF: No, in fact it turns out to be simpler if the proper computer controls are designed.
ABG: Apart from the batteries, what products or technologies have you used to try and reduce the weight of the vehicle?
AF: Weight is always critical to vehicle design. We have demonstrated that when using metal hydride and some light weight materials we can design a PHEV with a 60 mile or 100 km electric range for the same weight as a conventional car with the same or better performance. With lithium batteries it should be possible to be lighter. The reason is we use permanent magnet (PM) motors and downsize the engine to about one third or one quarter the size of a conventional engine.
We also use a simple and light continuously variable transmission (CVT). The weight of the powertrain is reduced to about one third of that in a conventional car. The balance is used for the batteries. This formula has given us 60 miles of all electric range using metal hydride and will give us even more using lithium.
ABG: How do permanent magnet (PM) motors differ from conventional electric motors?
AF: PM motors are more efficient and half the weight of induction motors used in industry to provide the same power. Also, automotive power is differently rated from continuous industrial power.
ABG: How long has it taken you to develop the controls hardware for your Challenge X entry? And what are the most significant challenges that you have faced?
AF: 30 years ago when I designed the first hybrid, I used all mechanical controls or electro-mechanical systems and put a lot of dependency on driver controls and interactions. As we have progressed, all the mechanical systems have been replaced with electronic computer controls. These computer controls just get better and better and the systems are becoming easier to tune and operate. Our vehicles drive like a standard vehicle with only accelerator and brake pedals, and the automatic transmission PRNDL selector.
ABG: What steps do you take to tune your vehicle once it is built?
AF: The vehicle we build should be completely automatic and require no additional effort on the driver's part except to plug it in. If you forget to plug it in you simply use gasoline instead at four times the price to go a given distance. If you wish to become totally energy independent, you can go out and buy a set of solar panels for your house and integrate your car and home electric system and use no petroleum or coal power until a rainy day. Even then you have a choice of using grid electricity or gasoline.
ABG: Has the vehicle lost power by moving to a powertrain based on a Toyota Prius engine or does the electric motors help make up the difference?
AF: The vehicle we are constructing will go 50 miles / 80 km or so on electricity alone using no gasoline but it also has 50 percent more power than a conventional gasoline 3.5-litre V6 engine. So our Equinox goes like a rocket since it weighs no more!
ABG: What were the major challenges in modifying the competition GM Equinox to be a flex-fuel vehicle? Did you have to develop a system to automatically detect the alcohol content of the fuel and modify the engine tuning accordingly?
AF: The modified Equinox actually has no GM powertrain components at all. We have designed everything ourselves to make the Toyota Prius engine to be flex-fuel. We used the GM flex-fuel sensor only.
ABG: I understand that you will be taking a trailer full of solar cells with you to the GM proving grounds in Michigan to help charge up your PHEV Challenge X entry. What photovoltaic technology are you using and what area of solar cells do you need to charge your vehicle?
AF: We are using borrowed, old solar cells of about 200 square feet or about 20 square meters. The eventual idea is to have these cells installed on garage roofs or house roofs or business roofs or shopping centre roofs in place of ordinary roofing materials, then use a plug to transfer the energy to the car. If the car's batteries are full then the energy can be fed to the house or factory or shopping centre to displace their electricity use.
ABG: How do you rate your chances in this year's competition?
AF: High I hope!
I'd like to thank Prof. Andrew Frank for his time in answering all of my questions and for sharing with us more background and insight to the challenge of building a competition PHEV. It sounds like Team Fate are off to a great start with their entry in the Challenge X: Crossover to Sustainable Mobility competition and we wish them all the best.
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