# 1-1/2 hp 120 volt Permanent magnet motor



## Solcar (Nov 8, 2007)

Consider using 48 volts of batteries. Then use a solid state voltage doubler. I have built voltage doublers and quadruplers. Done right, they are efficient and relatively simple, circuit-wise.


----------



## Qmavam (Aug 17, 2008)

Solcar said:


> Consider using 48 volts of batteries. Then use a solid state voltage doubler. I have built voltage doublers and quadruplers. Done right, they are efficient and relatively simple, circuit-wise.


How would you implement motor speed control?
Or do you drive your doubler, quadrupler with the speed controller?
Seems like the doubler would need enormous capacitors.
I wonder if you could drive a transformer with a motor speed controller
and then rectify the output for the motor.
Mike


----------



## samborambo (Aug 27, 2008)

Your cheapest option, if you do it yourself, is to rewind or reconnect the windings inside the motor.

Inspect the rotor and see what your options are. Rewinding means you'll have to split the windings in order to create parallel windings.

Sam.


----------



## Solcar (Nov 8, 2007)

samborambo said:


> Your cheapest option, if you do it yourself, is to rewind or reconnect the windings inside the motor.
> 
> Inspect the rotor and see what your options are. Rewinding means you'll have to split the windings in order to create parallel windings.
> 
> Sam.


Motors that I have opened looked pretty hard to rewind. There was just a little slit through which to try to slip the windings. It looked like they would get nicked up or at least be loose on the armature.


----------



## Solcar (Nov 8, 2007)

Qmavam said:


> How would you implement motor speed control?
> Or do you drive your doubler, quadrupler with the speed controller?
> Seems like the doubler would need enormous capacitors.
> I wonder if you could drive a transformer with a motor speed controller
> ...


I did the controller on my e-bike as part of the voltage quadrupler like you might have guessed. But I was trying to keep space and weight to a minimum. It took a long time to get it to work.

It is much more straightforward to set a voltage doubler to put out the 48v and then use a PWM circuit chop that for motor speed control.

My device even has the charger built-in. It uses the same transformer as the voltage quadrupler. But mine only puts out about 250w, so at a 50khz switching, I used 2 microfarad capacitors in the booster circuit. Like you were suggesting, if you just use a doubler and not a quadrupler, you can use just a transformer with 1 winding tapped for push-pull. I then took the output of that to charge pumping capacitors to get X voltage.

I designed my circuits using SwitcherCAD, the best free electronics simulator out there. I used the SG3525 chip as the controller, but it seems possible to use the CD40106, my favorite IC chip of all. You can get an even duty cycle using the CD40106 if the oscillator uses two gates, two capacitors, and two resistors.


----------



## Solcar (Nov 8, 2007)

Solcar said:


> I did the controller on my e-bike as part of the voltage quadrupler like you might have guessed. But I was trying to keep space and weight to a minimum. It took a long time to get it to work.
> 
> It is much more straightforward to set a voltage doubler to put out the *96v* and then use a PWM circuit *to* chop that for motor speed control.
> 
> ...


Edits in bold.


----------



## Qmavam (Aug 17, 2008)

Solcar said:


> I did the controller on my e-bike as part of the voltage quadrupler like you might have guessed. But I was trying to keep space and weight to a minimum. It took a long time to get it to work.
> 
> It is much more straightforward to set a voltage doubler to put out the *96v* and then use a PWM circuit *to* chop that for motor speed control.
> 
> ...


 I'd be looking at about 2kw to 3kw as a power output. I was hoping to 
do the speed control at lower voltage 48v to 72v to keep the cost of the controller down. (although I was looking at buying not building)
The SG3525 and CD40106 are quite different, but I can see using the CD40106 as the doubler/quadrupler and SG3525 as the speed controller.
I have used LTspice (switchercad), it's a neat program.
I picked this motor up for $5.00 at metal scrap yard, and was hoping to 
find a way to implement it, it came from a floor polisher.
Mike


----------



## Solcar (Nov 8, 2007)

Qmavam said:


> I'd be looking at about 2kw to 3kw as a power output. I was hoping to
> do the speed control at lower voltage 48v to 72v to keep the cost of the controller down. (although I was looking at buying not building)
> The SG3525 and CD40106 are quite different, but I can see using the CD40106 as the doubler/quadrupler and SG3525 as the speed controller.
> I have used LTspice (switchercad), it's a neat program.
> ...


I have some circuit ideas done in LTspice that you can tinker with. They are at my Yahoo! switchmode group, in the files section.

http://tech.groups.yahoo.com/group/switchmode/

It is possible to do everything with the CD40106. The SG3525 is simpler for push-pull transformer drive, though.

If you use the sg3525 and implement current limiting just right, then you can drive a motor at 100v from a 48v battery. I had to tinker with it for a whole summer to get it right. In theory, it is not hard, though. It would be harder from 48v than it was for me from 12v since the sg3525 has an absolute maximum voltage rating of 40. (The CD40106 can handle up to 16v.) You might then just double 36v to 72v to address that issue.

One important thing: Is your motor permanent magnet? If not forget it as being too inefficient. Another important consideration is whether it has ball bearings and spins easily.


----------



## Qmavam (Aug 17, 2008)

Solcar said:


> I have some circuit ideas done in LTspice that you can tinker with.
> They are at my Yahoo! switchmode group, in the files section.
> One important thing: Is your motor permanent magnet? If not forget it as being too inefficient. Another important consideration is whether it has ball bearings and spins easily.


 I have seen others write about the efficiency of permanent magnet motor
vs. series wound. I don't believe there is that much difference. ( I say that
waiting to be corrected with data)
If there was a great difference, I think I would see mostly permanent motors used on electric vehicles, and I don't.
Anyway, yes it is a permanent magnet motor with ball bearings!








Mike


----------



## Solcar (Nov 8, 2007)

Qmavam said:


> I have seen others write about the efficiency of permanent magnet motor
> vs. series wound. I don't believe there is that much difference. ( I say that
> waiting to be corrected with data)
> If there was a great difference, I think I would see mostly permanent motors used on electric vehicles, and I don't.
> ...


Good about the motor. It will probably work well.

I don't have data, but realize that series wound input current must go through something like twice the copper. So look at copper losses being doubled. The extent of such losses depends on the load on the motor. On my e-bike, at full load, copper losses are close to 100% of the wasted energy. I have a high quality Pittman motor, which is why the unavoidable copper losses are so overwhelming. 

An important factor for efficiency is construction quality. Consider how inefficient hobby-type motors are. That can be verified by the no load power consumption.

PS. cool about your LTspice use.


----------



## Qmavam (Aug 17, 2008)

Solcar said:


> I don't have data, but realize that series wound input current must go through something like twice the copper.


 This is about right, although I have seen some data that the field
resistance is slightly lower than armature resistance.


> The extent of such losses depends on the load on the motor.


 Yes, I^2R losses are max at max load


> On my e-bike, at full load, copper losses are close to 100% of the wasted energy.


 I'm not onboard with that, I'd go 1/2 copper losses and 1/2 friction, iron
and stray load losses.
I've spent an hour or two searching for data, didn't find a lot, but here
is one site with a graph of losses. (left side of page) The motor seems to 88% effficient at full load. 
Graph here shows 6% I^2R (copper) losses, if split evenly that would be 3% copper loss of series field.
http://resources.schoolscience.co.uk/CDA/16plus/copelech3pg3.html
So my best guestimate is 2% to 3% loss of efficiency from a series
winding versus permanent magnet motor.
If you had a 30 mile range and improved efficiency by 2.5% you would
get an additional 3/4 mile.
What do you think?
Mike


----------



## Solcar (Nov 8, 2007)

Qmavam said:


> This is about right, although I have seen some data that the field
> resistance is slightly lower than armature resistance.
> Yes, I^2R losses are max at max load
> I'm not onboard with that, I'd go 1/2 copper losses and 1/2 friction, iron
> ...


I have a lot of experience with my motor. The reason why its copper loss is so high at max power is that it is a servo motor designed for just 60w, or so, continuous output. With a 1 ohm armature resistance, that gives 144 watts heat dissipation stalled at 12v input. Then, efficiency is 0%. Efficiency depends a lot on the current that the motor is given, what the voltage is, and how fast it is spinning.

So, since your motor is rated so high output power, and if you limit the current input, taking into account the RPMs, I agree that you can reduce the extra copper losses down to a negligible level.

So, I think your assessment fits. If your shaft spins freely, your motor might lose 2-3% over a permanent magnet motor like my Pittman one, which suffers negligible friction losses. I operate it from my homemade current limited controller which can take the voltage up to about 40v even though it is a 12v motor.

It turns out that with dwindling world resources, permanent magnet motors using rare earth magnets might phase out of production. So, in that regard as well, you may be on the ball.


----------



## Xringer (Oct 12, 2008)

Qmavam said:


> Hi All,
> I landed upon a 1-1/2 hp 120 volt, 15 amp, 3200 rpm permanent magnet motor.
> The label says 120 volts AC. but it has a fullwave
> bridge wired inside to make it DC.
> ...


In case no one else told you, the output of that fullwave bridge is going to be about 170VDC. (120VAC RMS x 1.414).?.

The motor will run on lower voltage, but not too well. (Power=current squared, times Resistance).
And, the resistance of that motor might be a little high, to match the 170vdc. So, if you used 17VDC, it would draw ~1/10 of it's normal current, producing very little HP.


----------



## Qmavam (Aug 17, 2008)

Xringer said:


> In case no one else told you, the output of that fullwave bridge is going to be about 170VDC. (120VAC RMS x 1.414).?.


 The output of a fullwave bridge is 170 peak half sinewave.
it is equivalent to 120 dc power source.



> The motor will run on lower voltage, but not too well. (Power=current squared, times Resistance).
> And, the resistance of that motor might be a little high, to match the 170vdc. So, if you used 17VDC, it would draw ~1/10 of it's normal current, producing very little HP.


Yes, I have no interest in running the motor at a lower voltage. I would
like to run the motor at a higher voltage than it's design. 
If this was a 24v, 36v, or 48v motor it would be a piece of cake.
The problem is a controller for a high voltage motor.
Mike


----------



## causalitist (Feb 6, 2009)

i'm using a 130vdc motor, I dont understand why all the voltage doubling etc.
i'm just using 148v lithium polymer batteries, much more efficient. they cost $170, but 148v, 40A continuous, 60A 1 minute discharge is 5.9 - 8.9kW, 
they are only 4amp hour, but thats 593Watt/hour , i plan to parallel more, but this is fine for now.

they weigh about 4 pounds!, 5" x 8" x 3" 
thats a great price for lipos! 
i have two speed controls, 
i use the sg3525 on one, and the sg3524 on the other... they are pretty much the same, but i like the two current sense pins on the 3524 better.
they are both at 20khz, which is ideal for most setups, why the high frequency on yours? all you need if for it to switch much faster than the motors time constant, after that your just adding to switching losses... at least thats my take on it.. 

thats my suggestion, buy the batteries for the voltage you need, and use the sg3524 or 3525. 

oh! and check out the ACS754SCB-200 Allegro hall effect current sensor.
what do you guys use for current limiting? you do right? 
that sensor works GREAT with the sg3524 current sense pins.. it puts out 200mv plus 10mv/amp.. i just put a little voltage divider and trimpot on its output and sent that right to the current sense pins.. i have it set to 5A to 50A current limit.. perfect for these high voltage motors on bikes.
*
*


----------



## causalitist (Feb 6, 2009)

as far as voltage problem for the actual controller... i use either fda2712 250v mosfets , or Irfp4668 200v mosfets << these are AWESOME! they are 8 milliOhm, 130AMp , thats unheard of for that voltage. i started off with the 250v fets until i knew i had all voltage spikes under control.

my batteries are actually 8 seperate 5 cell packs.. so 18.5v each...
Tap ground at mosfet source
tap v+ at the first pack in series (18.5v) .. 

there is a 10 Ohm resistor right at each tap...
these both go through diodes,
then positive is sent through a lm317 voltage reg set up as a 200ma current regulator(all it takes is one resistor)
few ceramic caps, and one low esr 470uf electrolytic cap across them to dampen anything. 
a zener v+ to ground, to stop anything over 20v

that goes to the driver(tc4422)
and thru a positive 8v voltage regulator for the sg3524
sounds like alot, but its not at all, all fits in 1 square inch.

not sure how experienced you are, but i could point you to the components needed. 
i have not found anyone remotely interested in what i was doing.. hopefully we can exchange information here... you would think most people would be interested in 60mph bicycles! and to think... 6 months ago i didnt even know what PWM was.

there is a circuit of the sg3524 being used for a 130vdc motor in a different thread:
http://www.diyelectriccar.com/forum...c4420-13763.html?p=100728&posted=1#post100728

scroll down a bit. .. he doesnt show how he got a clean low voltage source for the chip, but thats the circuit i started with.
i love the ramp speed.. forget the current sensing using the resistor,,, thats no good.


----------



## budzlife (Mar 27, 2009)

yes just like my electric motor with 120 volt also, i actually convert it to 160 volt for long lasting...performance


----------



## COS (Dec 23, 2008)

170V from 120VAC after fullwave bridge? Correct me if i'm wrong but 120VAC IS the RMS DC Equvalent. So theoretically the most you are going to get from the fulwave bridge is 120VDC.

Personally I would get a puresine inverter plugged into a 12VDC battery and rectify the output and use a PWM for your throttle.
but that's just me.
________
Live Sex Webshows


----------



## Xringer (Oct 12, 2008)

COS said:


> 170V from 120VAC after fullwave bridge? Correct me if i'm wrong but 120VAC IS the RMS DC Equvalent. So theoretically the most you are going to get from the fulwave bridge is 120VDC.
> 
> Personally I would get a puresine inverter plugged into a 12VDC battery and rectify the output and use a PWM for your throttle.
> but that's just me.



http://en.wikipedia.org/wiki/Root_mean_square

"Peak values can be calculated from RMS values from the above formula, which implies _V__p_ = _V_RMS × √2, assuming the source is a pure sine wave. Thus the peak value of the mains voltage in the USA is about 120 × √2, or about 170 volts."

Normally, the output of a full-wave bridge has a capacitor across.
If you apply 120VRMS (wall outlet) to the bridge input, the cap will
charge up to about 170 VDC. 


Notice the 240VAC transformer that seems to be making 350 VDC...


----------



## COS (Dec 23, 2008)

Xringer said:


> http://en.wikipedia.org/wiki/Root_mean_square
> 
> "Peak values can be calculated from RMS values from the above formula, which implies _V__p_ = _V_RMS ? ?2, assuming the source is a pure sine wave. Thus the peak value of the mains voltage in the USA is about 120 ? ?2, or about 170 volts."
> 
> ...


 
Interesting. So what your telling me is that all the digital Fluke meters I have used measuring RMS AC voltage of 110VAC or 120VAC RMS and rectifying that to a ~110VDC or ~120VDC is wrong? All classes ever taken teaches that the rule of thumb is Peak-Peak is 1.414 an Peak is .707. So just out of curiousity, what is the VDC reading WITHOUT the additional components which also connects to the below circuit? After all, when I am going to rectify an AC signal to DC it's going to have just one AC source.
________
Extreme q


----------



## Xringer (Oct 12, 2008)

COS said:


> Interesting. So what your telling me is that all the digital Fluke meters I have used measuring RMS AC voltage of 110VAC or 120VAC RMS and rectifying that to a ~110VDC or ~120VDC is wrong? All classes ever taken teaches that the rule of thumb is Peak-Peak is 1.414 an Peak is .707. So just out of curiousity, what is the VDC reading WITHOUT the additional components which also connects to the below circuit? After all, when I am going to rectify an AC signal to DC it's going to have just one AC source.



If you look at an AC sine wave with an Oscilloscope, you can see the peak voltage. (Or Peak to Peak).

But your VOM meter is not going to display Peak. It's calibrated to display
the DC *heating* equivalent voltage of AC. Also called AC RMS.. 

Since AC has all those peaks and valleys, and voltage dropping to Zero 
during the cycles.. It's not always at full power, like DC.. 

_V__p_ = _V_RMS × √2 (√ of 2 is 1.414).


This formula applies to resistive loads like a space heater coil etc.
When you apply AC to an inductive or capacitive load, the frequency
of the AC will cause the load to be more resistive(XL) or less resistive(XC)
depending on the frequency.


----------



## COS (Dec 23, 2008)

Xringer said:


> If you look at an AC sine wave with an Oscilloscope, you can see the peak voltage. (Or Peak to Peak).
> 
> But your VOM meter is not going to display Peak. It's calibrated to display
> the DC *heating* equivalent voltage of AC. Also called AC RMS..
> ...


 
OK, I get you. You're looking at the AC "Effective" DC equivalent to the imedence of a device(s). 

Thanks for the clarification.
________
spanish girl Webcams


----------



## soon2bEV (Mar 14, 2011)

Hey all. I am curious how everything turned out with this. I had a bike working pretty well getting to around 40mph give or take, but I blew the motor, well, toasted would be more appropriate. I am looking to possibly do something similar with an AC motor. This was an idea not foriegn, just seemed like DC was less expensive. I am able to build circuits with direction, when I have a motor chosen I will have more questions.
Let me know how it went.
Thanks
_d


----------

