If you are designing an all electric car, in-wheel electric motors could replace any on-chassis motors, and having four of them independently coordinating whether they function as generator or motor allows sophisticated power management - improving efficiencies. In-wheel motors also allow more payload space on the main chassis.
According to Mitsubishi’s 2005 Annual Report, page two, in May 2005 they announced in-wheel motor technology ready to deploy. In-wheel motors eliminate the need for a transmission or power train and overall they are far less expensive to maintain. They represent a huge leap forward in automotive technology.
Another significant innovation coming soon, also less expensive to maintain, is the Serial Hybrid Car, where a diesel engine turns a generator to charge a battery-pack and power an all-electric drivetrain. These cars were waiting for two things - ultra-clean 40% efficiency diesel engines, and batteries with an energy density of 200 watt-hours per kilogram. That day is here.
A serial hybrid car can run on two things - battery power or power from an on-board diesel generator. Using battery power, a mid-sized car - loading up on electricity at $10 per kilowatt-hour from the grid - can be driven for under four cents per mile. Using diesel fuel at $3.00 per gallon, the same serial hybrid car can transfer electricity directly from the generator to the motor and be driven for ten cents per mile - about thirty miles per gallon.
The range of a serial hybrid car depends on the size of the diesel engine, the capacity of the fuel tank, and the quantity of batteries, to name a few key factors, but 300+ miles is more than feasible. The tradeoffs between range, weight, and price are infinite. Will a major automaker announce a serial hybrid car tomorrow at the Detroit International Auto Show 2007? And if so, will it be the real deal? Because the serial hybrid car is waiting to be built - inexpensively - and sold by the millions around the world.
Later, with in-wheel motors and on-board reforming capacity, if advantageous, fuel cell systems could replace the diesel/battery systems on the same chassis and drivetrain. It takes time to green a newly industrialized planet, but evolution and creation are wonderful things.
January 7th, 2007 at 11:13 am
Serial hybrids don’t require 200 watthours capaciity per kilogram batteries. That’s total nonsense. The capacity usually desired by a plug-in is enough for about 30 to 40 miles of all-electric driving. 78% commute fewer than 40 miles a day and half the cars travel less than 30 miles each day. That means about 8 to 10 kilowatt hour capacity battery pack, if you’re talking about mileage. A kilowatt hour capacity Altair battery weighs 28 pounds, or 280 for 10 kWhr capacity, which easily meets GM’s stated goal of a battery pack less than 400 pounds, which I consider a silly limitation altogether.
January 7th, 2007 at 7:13 pm
Kent, I agree you can make a serial hybrid work on less. As noted in our post today - commenting on GM’s announcement of a serial hybrid - it appears their batteries do achieve around 200 watt hours per kilogram. Their Chevy “Volt” concept car is midsized, and has a battery-only range of 40 miles. This would mean it would have a roughly 500 pound battery pack at 100 kilowatt-hours per kilogram, and as you point out, GM wants to keep their battery pack lighter than that. But at 100 KWhr per Kg, a serial hybrid would be a viable vehicle.
The key is when and if this car will actually be available for sale. A 40 mile range will fulfill most normal duty cycles, yet the car has a range of 600 miles running on gasoline or some other fuel for the onboard generator. This is a terrific innovation, albiet way past due.
January 8th, 2007 at 1:52 am
[...] If you are designing an all electric car, in-wheel electric motors could replace any on-chassis motors, and having four of them independently coordinating … Source http://www.ecoworld.com/blog/2007/01/06/in-wheel-electric-motors-found/ [...]
May 19th, 2007 at 8:12 pm
The key to serial hybrids (series hybrids) is/are the wheel motors. This eliminates all the unnecessary weight of the components used to transfer the power of a central engine or motor to drive the wheels, if the wheels are their own motor. I am guessing that GM has NOT started this Chevy Volt project from a clean sheet of paper because, it appears that they are planning to use a central traction motor on a transaxle to deliver power to the wheels. There is no doubt that a high percentage of users would benefit from a car that can run 40 miles on a charge but a much higher percentage would benefit form a car that could go 100 miles or more on a charge and, another consideration that needs to be taken in to account is the fact that the battery’s ability to operate at 100% efficiency (the ability to give 40 miles after each charge, on an ongoing basis) is a diminishing return as the batteries age. And that, in my opinion is the reason the battery pack should be designed for a more “real world” use. The weight savings of the mechanical components that will be unneeded with the use of wheel motors can be used to off set the extra batteries needed for the extra range and the space savings in the engine compartment where the traction motor and transaxle would ordinarily be can be used for the motor/generator set. The 1.3L trubocharged engine for the generator, as proposed by Chevy, seems overkill to me.
April 29th, 2008 at 3:20 pm
I’ve recently discovered that the cost of my electricity goes from 30 cents a Kwh in the afternoon, to as little as 2 cents a kwh after midnight. The system for moving my car would also move my electrical load from 30 cents to 2 cents. Let’s keep this ‘power pack” in mind as we consider our energy consumption in total.