electric motor for transpotation

1 HP=746 Watts

746 watts per wheel time 4 wheels is 2984 watts. watts = volts times amps A not so clever assumption would be 12 volts (pre hybrid technology standard ) so 2984/12= 248 amps 12 volt car battery= 45 amp hours; 70 amp hour is what my old big car batteries were rated. These ratings are based on a typical automotive current draw of around 3.5 amps. Have fun with your calculations. milo

100 HP Huge power for transportation. You will need high voltage battery bank, 72 to 120 volts, whether some more. Amp. rating for the batteries is dependent with the requested driving time. First you need to know the Amp rating for the motor.

First try to find the suitable DC traction motor, and then compose the battery voltage and amp. configuration according the manufacturer's recommendations.

When calculating the battery capacity, assume that ten times of Amp/h of motor amp rating means approx 9 hour of transportation at the full load. (It's not a good way to nullify the batteries, except the deep charge types.

And finally you will need an adequate driving system to control the speed and torque for the motor in such high amps.

Trying to control the speed by using powerful bulk resistor banks, similar with the old VW2 submarines is not a good idea.

Coming to the mechanical side of the business, you need a differential gear, to control the speed of two wheels when turning.

Can the controler built to sense speed - the outer wheel speeds up to compensate for the slow inside wheel?

As I mentioned in my previous post, 100 HP (Approv 75 KW) is a huge power to control. Giant heavy battery bank. High currents to deal with, etc.

However coming to differential gear problem to match the outer and inner wheels, you can solve the problem electrically.

Use two identical motors one for left hand side and the other to the right hand side. (An example 40 HP to left and 40 HP to right). (The second benefit of this, you can find those lower powered motors more easly than 100 KW.)

Connect the two motors in serial and power it from one controller.

In normal straight way, of which the loads on each motor is equal, the motors will turn with the same speed, because they are serial and drawing the same current.

During the turns, the inner wheel will be much loaded than the outer. The inner will try to draw much current. Since the two motors are serial connected and the mutual current is the same , the other (Outer) motor is less loaded and will try to turn faster. This will achieve the differential problem spontaneously .

Hope this will solve your problem.

Kindest Regards

Thanks that does help - 100hp on each wheel 400hp this is a market that can pay if they want to - 50hp per wheel 200hp is a nice family car - Can the Feild hold the wheel and on its outside of its surface and Armiture become the attchment to the frame or uni body - Thanks again George

...Or perhaps you can get an inverted motor with the rotor (armature) on the outside and the stator (field) and electrical connections on the inside attached to the suspension. Permanent magnet brushless?

Wait! brushless PM motors have the magnets on the rotor and the coils around it. If you take a standard PM motor (with the magnets on the outside and coils on the rotor) and throw away the brushes and connect the coils through the rotor shaft come stator shaft to commutating circuitry (variable speed) you have a cheap wheel motor.

Yes I realize this is a gross oversimplification. A guy can dream, can't he?

Hi Gordie Gii

I need to learn more on your suggestion in connection with PM motor modification.

Do you imagine to get rid of the brushes as well as the commutator.

Feeding the fixed rotor directly from a pole changing (frequency) inverter and let the permanent magnet stator to spin around the rotor ?. (I am aware that Stator is inside and Rotor is outside now.)

It sounds workable.

However I am in doubt what's the maximum power of can be reached by using permanent magnets for the motors? What I have seen here are in the range of maximum to 1 Kw.

I am not sure a fifty Kw motor available with permanent magnets.

What I have seen here are in the range of maximum to 1 Kw.

I have a couple 6 kw continuous (15 kW peak) DC permanent magnet motors in my shop. The Prius or Insight uses perm magnet DC brushless motors of perhaps 50 kW. There are a couple small motor prototypers (almost manufacturers) that have brushless DC motors up to about 120 kW (designed with vehicle propulsion in mind), if I recall.

Thanks Blink .

I were checking for PM generators as well as PM motors among the Chinese manufacturers, in connection with the wind power.

However I could not spot a manufacturer producing PM units over 1 Kw. (I were assuming they are not manufactured due the high dragging force when they are not powered. This is only my own opinion)

I would be very pleased if you send me a link for such PM units in such higher Kw's . It could be useful for my other projects.

I have no detailed info in connection with the Hybrid Toyota Prius motor. It is very new yet. However it is not commonly sold in the markets to buy one and make trials for different projects such as for the header of this thread.

Kindes Regards

Hi,

The motors from Mars (which are sold from the US but produced in China) range up to about 6 kW continuous, 15 kW peak)

Perm makes brushless motors up to about 30 kW continuous (along with PM brushed motors).

Agni Motors makes brushed PM motors of up to around 26kW (or more by special order) I believe.

Some hobby motors for large RC airplanes have amazingly high outputs. If I recall, some of the "outrunner" motors (built inside out) can be a couple kilowatts peak.

Hope this helps,

Blink

Thanks.

I am checking all.

From my coments sent - Ford has EX 150 truck with 4 wheel motors they claim 600hp - would any one happen to know what the size of the wheel motors - Ford claims the batteries wieght is 1000lbs but what they took from the truck is the same or more- can not find the range? Thanks G.D.

The Ford uses the Flightlink motors. They claim that the 1000 lb battery pack provides 75-100 mile range, which sounds about right for lithium.

The rear wheel torque in first gear for a typical V8 truck is about 2800 lb- ft (350 lb-ft at engine times an overall reduction of 8) (This varies, of course, depending upon gearing, engine etc -- it is much higher than this for a diesel truck). So although 2000 ft-lb combined torque from the wheel motors looks impressive in print, it is not the stunning figure that article seems to imply it is.

The Lightning from the UK also has been prototyped with these motors, as has Volvo's ReCharge concept car.

would any one happen to know what the size of the wheel motors

Do you mean physical size? They pretty much fill the entire wheel -- they are the green things in the pictures.

I note that Protean's (new name for PML FLightlink) website page re the Ford says this:

Four Hi-Pa Drive motors each weighing 66 pounds, so unsprung weight is not an issue

66 lb is actually a huge issue. Above I mentioned 28 lb as the weight for these motors in the Mini -- My memory was (is) probably faulty. The Mini motors were probably really 28 kg (61.6 lb). (Same basic motor, slightly lighter duty bearings, etc, I'd guess.) The Mini motors had the same specs (they were quoted as 160 hp each, instead of 150). A four wheel drive truck is the only light vehicle in which you can even come close to saying that 66 lb of unsprung weight is not an issue -- because some of these trucks still have live axles in the front -- and so have very high unsprung weight. This is what gives them their skittery performance on washboard roads.

The combined weight of a wheel and tire on a Mini is 30 lb, so adding 60 lb is a big deal. For the Ford, it is far less of a big deal, but still a lot of weight to fling around on each bump. A truck live axle certainly weighs more than the two motors (132 lb).

Exactly.

The controller supplies the total power needed. And this total power is spontaneously shared between outer and inner wheels, because they are serial connected. (In only serial connected case)

In my opinion you don't need 4 wheels to drive. this brings trouble to match the speeds of the front and rear wheels, otherwise they will drag.

Therefore let the front wheels to free wheeling.

What you need is 30HP +30HP two motors for right and left sides. This makes a total 60 HP. Good enough anf practical for commuting such as you are powered with a 1400CC gasoline engine.

For more power you will need more big batteries More space, more money, more weight.

Kindest Regards

I think it was implied that each wheel would have its own motor so no differential would be required. I think if you used a torque control method the speeds would take care of themselves.

100 HP per wheel is WAY too much. we have all heard of 400 HP engines in cars but car engine HP is rated differently from electric motor HP. I believe a factor of about 4:1 or 5:1 was recommended (in a book I read about electric vehicle design) so a kick-ass electric sports car would only need about 80 to 100 HP total, or 20 to 25 HP per wheel.

That's still a lot of power to be hauling around in batteries, so you might want to consider regenerative breaking. You also might want to consider AC motors with VFDs with the batteries connected directly to the bus capacitors.

Just some food for thought...

Gordie.

Thanks Gordy this give some very good insite on this project -- How many people would consider being part of a project like this?

Electric wheel motors are rated like other motors. Typically, the output is specified in hp while the input is specified in kilowatts (which can be converted to hp by dividing by .746) (One kilowatt = 1.34 hp) The difference between input power and output power (with both expressed in watts) shows the efficiency of the motor. (Typically the efficiency of advanced wheel motor prototypes is very high -- 94% including the controller loses, or so.) There are no large (100 hp) wheel motors in production for automotive use. There are several prototypes that could become production items, if engineers were convinced that wheel motors had enough advantages to overcome their disadvantages.

PML Flightlink (now Protean Electric) is the best known promoter of the wheel motor concept for cars and light trucks (although there are several Chinese companies selling wheel motors for smaller vehicles). I considered their motors for a prototype vehicle, but even in production volumes, the cost was far too high to be worth pursuing. (My $18,000 retail vehicle would have needed $18,000 in motors and drives alone, if I recall -- the vehicle price would have doubled.)

The advantages of wheel motors:

- Slightly better efficiency can be possible by eliminating transmission gear reductions

- Four wheel motors makes a mechanically simple four wheel drive system with the possibility of independent wheel control for stability control, etc.

- Drive shafts and transmissions are eliminated.

The disadvantages:

- Four individual wheel motors are more expensive than a single large motor.

- Four channel control or four individual controllers are more expensive than a single controller.

- The unsprung weight at each wheel is very high with wheel motors. (This is one reason that wheel motors were first widely used in heavy construction equipment rather than in cars.) High unsprung weight leads to poor ride and handling.

- The range of motors available is very small, and the physical mounting arrangements are unique to each wheel motor, so you cannot easily source several motors for prototyping, or for having alternative suppliers.

- Traditionally, maximum speeds are limited with wheel motors: the same device that is suited to the very large torques required for grade climbing is not suited to high rpm.

- Modifications in a prototype that could be handled by simple gearing changes may require a completely new motor which might not be available.

- Existing car chassis are not built for wheel motors, so conversions are much easier with a motor that can fit where an ICE would.

The most serious limitations are weight and cost, and even very expensive wheel motors are still heavy. (I notice that the Mini used to be the poster child for the PLM Flightlink motors, but now it is a Ford F150 -- a much better candidate, because the motors are a smaller portion of the total weight, and ride and handling issues are not as critical.)

Typically, higher performance electric vehicles operate at high voltages, so the wiring sizes can be reasonable (watts = amps x volts, so a 100 hp [75,000 W] motor could use 200 A at 375 V, or 400 A at 188 volts. Four motors would require a total current draw from the batteries of four times these values.)

PML Flightlink was once promoting the idea of using no friction brakes at the wheels, to reduce unsprung weight, but this is a hard sell, I think.

Wheel motors have worked very well in construction equipment for decades, so the idea is certainly workable. The cost could come down dramatically if the volume were high, but how do you get the volume high if the initial cost is high? One possibility is that the Chinese end of the market will grow to more typical automotive sizes. (This seems fairly likely, and the motors will probably improve in weight and performance.) The other is that one of the exotic electric cars that has been proposed using the Flightlink motors will sell in volume -- but that seems unlikely.

I didn't express myself clearly

-Electric wheel motors are rated like other motors.

True.

What I meant is that car engine HP are usually quoted as peak power at the ideal RPM. What you get accelerating from a stop is much, much less. Electric motors usually have a much flatter torque vs RPM curve so to get a reasonable acceleration only requires about one fifth of the quoted HP of a similar ICE vehicle. Perhaps one third for a muscle car.

- Four motors would require a total current draw from the batteries of four times these values.

Not if each was a quarter the size of the single motor.

-Wheel motors have worked very well in construction equipment for decades

That's cool. I always thought construction equipment used hydraulic motors.

Although I like the idea of wheel motors in theory, the drawbacks would incline me to wait for technological advances in motors. However I think that the advantages of four independent motors outweigh the drawbacks.

Two motors (one for both left wheels, and one for both right, as was suggested in another post) won't work since each of the wheels travels a different distance (except for a specific turn radius where the inside front and outside back wheels are on the same radius) so you'd still get wheels fighting each other, unless you went with four wheel steering and the associated expense.

You could even eliminate the need for power steering by applying extra torque to the outside wheels.

- Four motors would require a total current draw from the batteries of four times these values.

Not if each was a quarter the size of the single motor.

Of course, but I was responding to the original post, which talked about 4 100 hp wheel motors, which would consume the same power (other things being equal) of one 400 hp motor. The PML Flightlink motors are rated at 160 hp each, and their Mini demo car used four of these, for 640 hp total -- a ludicrous amount of power for a Mini. It seems to be the vogue to produce prototypes and limited production runs of very high powered electric cars, as if to prove that not all electric cars are golf carts.

Of course, in use, these motors are rarely operated at even continuous power level, let alone peak power levels. (A Mini would have to be driven really, really fast to use 640 hp.)

-Wheel motors have worked very well in construction equipment for decades

That's cool. I always thought construction equipment used hydraulic motors.

The really heavy stuff (hauls trucks, etc) has what would be considered more or less leading edge stuff for a car: AC wheel motors, supercapacitor banks for regen, etc. The system on one of the Liebherr trucks (described in this article) is:

• A brushless Siemens generator is directly driven off the engine, supplying the truck's electrical ac drive system. The ac power generated by the alternator is rectified into dc current and then converted into variable ac frequency by inverters. Separate inverters power each of the rear Siemens wheel motors, which Liebherr said allows for totally independent power to be supplied to either set of rear wheels. The motors drive an L S two-stage planetary gear set, resulting in a reduction ratio of 37.3:1 to 43.7:1, depending on application requirements.

Although I like the idea of wheel motors in theory, the drawbacks would incline me to wait for technological advances in motors. However I think that the advantages of four independent motors outweigh the drawbacks.

I agree in principle, although the more sophisticated wheel motors (like the Flightlinks) already employ many quite sophisticated (and expensive) techniques for reducing weight, maximizing efficiency, etc. But still, the motors in the Mini were 28 lb each, which comes close to doubling unsprung weight at each wheel -- unless you eliminate the friction brakes, which few people will be comfortable with. A fundamental problem is that if an electric motor has high torque capability it is also heavy: just the weight of copper required for the high currents makes the motor heavy. If instead, the motor is smaller and lighter, then the wheel must contain a reduction gear unit, bringing the weight back up. For my own prototype (which is a very light vehicle) the motors from Flightlink ( the only supplier who was close enough to real production in the required sizes) were both too heavy and inadequate in performance, especially in grade climbing. (This was powering two out of three wheels. With three wheels powered, performance was just adequate, but the cost, already astronomical, was even higher.)

But I agree that the concept is really appealing. As you may know, the rollover control and active stability control used on the Volvo SUV controls each wheel individually to help keep the vehicle pointed where you want it to go, and wheel motors lend themselves to this kind of thing, without the complexity of controlling power delivery from an ICE and a hydraulic brake system.

electric motor is a electrical machine that tranform electric energy in mechanical energy. there are Electrical motors that use alternat current and others direct current. the units of power are HP= HORSE POWER= 0.746 KW ,the voltage units are volts, the units of electrical current= amperes, POWER = V X I= V X I COS &= WATTS; power= R X I2

Do u mean to construct this? Then u must be ready with battery banks in series-parallel connections to drive yr motor,bcos d amps is very high.

However,for the four wheel,u may need 300kw motor,but wt a margin of 25%,u may need up to 375kw electric motor.AC or DC volts,u need banks of batteries in series/parallel.

Good luck

Patrick Whowha

I am very happy with the good ideas and help i am getting - 30hp per wheel is plenty and just a two wheel may be considered - cost - how many people would like to be part of this project - ? would need Money and Talent in terms of knowledge - please send to gcdibble@comcast.net

If you are considering controlling two wheel motors with a single controller in series, then you loose the benefit of a simple form of traction control that can be implemented with separate controllers. Wiring the motors in series (if you can find DC wheel motors) provides differential control (a good thing) but also allows one wheel to spin at a much higher rate than the other, so it the road is slippery, you can get stuck.

Recent wheel motors are typically three phase AC (or brushless DC, which operate on a similar principal), and so cannot be wired in series, with speed being controlled by frequency.

If you are willing to have ordinary (non limited-slip) differential action, then a single standard (DC series, DC separately exited, or AC) motor going through a standard automotive differential will make for a more economical conversion (and, of course, such a differential could have mechanical limited slip built in).

To justify the cost and constraints of wheel motors, you really have to want their advantages, such as independent control of all four wheels. For a simple economical conversion, most people will go with a single motor either directly coupled to a differential, or coupled through a standard or modified automotive transmission.

The Tesla Roadster uses a single 150,000 watt AC motor directly coupled to the differential. AC motors have excellent low speed torque, and lend themselves to single speed transmissions (although the Tesla could have a slightly higher top speed if it had a two speed transmission).

Be careful in selecting motors. Ratings are not consistent in from one motor to the next. The Tesla 150,000 watt (200 hp) rating is not a continuous rating, whereas many motors are advertised at their continuous rating with the one minute peak rating being 2 or 3 times higher.

A very good source for seeing what others are doing (and with extensive list serve archives) is the EV Album (and the EVDL). You can search the album for vehicles using various motor types and brands, different battery types, etc. Many converters are finding that lithium chemistry batteries are lasting enough longer than lead acid to more than cancel the price difference, (if the batteries come from China) and the performance is much better because of lower weight.

Quoting :

Wiring the motors in series (if you can find DC wheel motors) provides differential control (a good thing) but also allows one wheel to spin at a much higher rate than the other, so it the road is slippery, you can get stuck.

This is a normal situuation even in the case of an ordinary mechanical differential.

When the road is slippery every wheel spins uncontrollable.

Going thru 150 kw or such powerful motors, This is an open negotiation of what power he needs.

It is obvious if the motor goes higher ratings, the batteries are also get bigger and heavier. This is the matter of enough space and weight.

A vehicle, built only to carry it's giant heavy batteries but no space for extra person or load is good for nothing.

Single motor, coupled to an ordinary mechanic differential may be a good solution. And also brings te benefit of regenerative braking as well as recharging the battery. Permanent magnet type motors are directly suitable for regeneration. The others can be negotiateable. Regenerative recharging in any case may be such low as under the expectations.

Going to AC solutions, with traction control may not be a good solution (As far as I know). Simple is better at the startup point for the beginner

Dealing with such inverters is the business of experts, engineers. Simple is better at the startup point for the beginner.

Kindest Regards

This is a normal situuation even in the case of an ordinary mechanical differential.

True, although it is very common that cars now come with electronic "traction control" to eliminate the problem of one wheel spinning while little torque is delivered to the wheel with better traction.

When the road is slippery every wheel spins uncontrollable.

Not entirely true. With an open (non-locking, non-limited-slip) differential, one wheel spins, and the other wheel, typically the one with better traction delivers little torque. A limited-slip (or locking) differential cures this problem, sending some of the torque to the wheel with traction. With open differentials, is is unlikely for both wheels to spin, unless the traction at each wheel is very low (e.g., glare ice). "Traction control", in its simplest form, applies partial braking to the spinning wheel to transfer torque to the wheel with traction.

Going thru 150 kw or such powerful motors, This is an open negotiation of what power he needs.

If you reread this, you will see that I was using the Tesla motor only as an example of a rating method, not as a recommendation to buy: the Tesla motor and controller is $25,000 -- probably more than the OP wants to spend. In industry, it is standard to rate electric motors on continuous power, but in the automotive world, this is not always the case.

It is obvious if the motor goes higher ratings, the batteries are also get bigger and heavier. This is the matter of enough space and weight.

A vehicle, built only to carry it's giant heavy batteries but no space for extra person or load is good for nothing.

Of course. However, the Tesla Roadster uses a 150 kW motor and has space for two people, some luggage, has outstanding acceleration and gets almost 200 miles per charge when driven conservatively. Hobby builders have built similar cars (based on Porsche Boxster chassis, for example) that perform nearly as well, for about half the price -- but that's still a lot of money.

Going to AC solutions, with traction control may not be a good solution (As far as I know). Simple is better at the startup point for the beginner

Dealing with such inverters is the business of experts, engineers. Simple is better at the startup point for the beginner.

I agree, in general, that implementing traction control is not simple. However, with two independent motors and no differential (with the motors best mounted inboard and driving through half shafts to each drive wheel) it is easy to use two controllers, each operating in speed control mode to prevent wheel spinning. But I agree that the complexity of two motors, two controllers, a non-standard final drive system will usually suggest a simpler approach is better.

AC motors are not unheard of, even in home-built electric vehicles. For the home builder, the controller is a "black box" and it doesn't matter whether what happens inside is PWM or inversion. If it were not for three wires to the motors instead of two, the builder would hardly know the difference. Most recent production highway-capable electric vehicles are AC (GM EV1, Chevy S10 pickup, Tesla, newer Reva, etc). AC motors and controllers remain expensive, however, so here in the US, most conversions use DC series motors.

There is definitely an advantage to simplicity.

Regards, Blink

Of course there is one big advantage to using AC over DC.

If a PWM output transistor fries shut on an AC system you stop and may even burn out a motor.

If a PWM output transistor fries shut on a DC system you'll be through that red light and in front of a truck before you can even remember where the kill switch is.

If a PWM output transistor fries shut on a DC system you'll be through that red light and in front of a truck before you can even remember where the kill switch is.

True, and no small concern -- it is not common but it does happen.

This is only an alternative idea.

May I offer to drive the wheels hydraulically and independently, and use single electric motor to power a common hydro pump.

Power transmission to the wheels hydraulically would be easier.

That sounds like it might be rather inefficient and prone to breakdowns or high maintenance.

I must admit, however, that I have thought about it myself.

How about four electric motors mounted on the frame with four independent U-jointed axles?