PWM Motor controller

[truesprocket]

an update

heres what I've been doing & it's coming along nicely this is a massive motor for this project but so are the batteries, I want to put 2 infront of the motor & 1 in a basket on the front for 18volts if I need it

 

[Killa-X]

Heh..Similar thing i thought of..I planned (once i find a motor) to use IGBTs for the PWM speed control. Looks like yours is going along good

 

[truesprocket]

IGBTs

Heh..Similar thing i thought of..I planned (once i find a motor) to use IGBTs for the PWM speed control. Looks like yours is going along good

looked at some IGBTs & that looks like a good fix, I read that most of the parts for a controller are in a big photocopier so I took one apart, I have boxes of elecrical & electronic suff I'm still hunting for & those IGBTs are supose to be in microwaves, money's my biggest issue right now so what ever I come up with has to be pretty close to free, can I hook a throttle to the IGBTs or would it requier a control system to make that happen? thanks for pointing in this direction going to try that bike today if all goes well, still to go , brakes, inline kill swith beyond the on off switch, pully cover so I don't loose a pantleg or worse, a board(for now) to strap the batteries to & for my feet, I'll post some pic's if all goes well, thanks again.

 

[truesprocket]

it's going!

Heh..Similar thing i thought of..I planned (once i find a motor) to use IGBTs for the PWM speed control. Looks like yours is going along good

well it moves! not fast enough & holly crap is it ever heavy! it's got to be 200 pounds, my batteries aren't very secure the on/off works but the thumb trigger works backward, turn it on & you have to hold the switch to disconnect, I'll have to chainge that, some pully dellema's but the belts tight now! more to come!

 

[Killa-X]

Heh, motors weigh a lot too. I was told you can get IGBTS out of electric stoves too.

Depends on how many amps. You can get mosfets online that can do high amps at 50V or w/e your use is...

This does 60V 270A constant
http://www.newark.com/international-rectifier/irfb3006pbf/hexfet-power-mosfet/dp/27P5254

100V 290A
http://www.newark.com/international-rectifier/irfb3006pbf/hexfet-power-mosfet/dp/27P5254

But, It helps to know what it will run CONSTANT. Because a motor if started hard can draw alot of power, and fets like these, have a pulse amperage of "1120A" so...Ones like these im sure would work, the 100V 290A has the 1120A pulse, and the price really isnt bad. You just WANT TO HAVE BIG HEATSINKS!!!!!

Me being a HV junkie..Id just use a 555 timer with Pot variable frequency and 50% duty cycle. Did it for a Coil winder, Foot-pedal speed control.

 

[truesprocket]

seen one of these before ?

I picked up a ac control board yesterday I bought 2 at $1 each is it useable for anything of substance? like a ac furnace blower motor or similar ? .my budy works at a scrap yard & he's keeping his eye open for the igbt's for me & an electric fork lift & of course batteries , I'm pushing for A123's but I'll take what I get, thanks & here's that board I grabbed.

 

[Qmavam]

Heh, motors weigh a lot too. I was told you can get IGBTS out of electric stoves too.

I think that would only be the new style induction stoves.

Me being a HV junkie..Id just use a 555 timer with Pot variable frequency and 50% duty cycle. Did it for a Coil winder, Foot-pedal speed control.

I think that's backwards, you want a fixed frequency variable
duty cycle. I did it for a coil winder too, I wound a 40" long by
8" diameter coil for tesla. One of those projects I need to finish.
Mike

 

[truesprocket]

24volt electric scooter control to run 40LB 12volt

I have a couple of these 12volt motors & yesterday I found my box of electric scooter parts, I have an 18volt controller & a 24volt controller that are good & 2 others I'm not so sure about but probably work to, would there be a problem with running a massive 12volt with the 24volt scooter control & can a premade controller be enhanced to handle a bigger load & deliver a higher output, the 18volt will only give the same output with 18volts or 24 volts, no speed increase at all, can I change that ?

 

[Killa-X]

I think that's backwards, you want a fixed frequency variable
duty cycle. I did it for a coil winder too, I wound a 40" long by
8" diameter coil for tesla. One of those projects I need to finish.
Mike

Well actually its not backwards. its a VFD. Voltage frequency drive. I kept duty to 50%, and adjusted the frequency, and I was able to go from a super slow speed (slower than 1 revolution in 10 mins (gear motor)) or the full 36V at maybe 200rpm. Vent systems also use VFD's, as at our school, if its really quiet, you can hear a pitch-sweep. Also, My motor was a universal AC/DC brush, if it helps to know.

 

[Qmavam]

Well actually its not backwards. its a VFD. Voltage frequency drive. I kept duty to 50%, and adjusted the frequency, and I was able to go from a super slow speed (slower than 1 revolution in 10 mins (gear motor)) or the full 36V at maybe 200rpm. Vent systems also use VFD's, as at our school, if its really quiet, you can hear a pitch-sweep. Also, My motor was a universal AC/DC brush, if it helps to know.

Is it a standard AC/DC motor designed for 60 hz or is it designed
for a wide frequncy range? Any links for the motor?
Thanks, Mike

 

[HelloYOU]

Well actually its not backwards. its a VFD. Voltage frequency drive. I kept duty to 50%, and adjusted the frequency, and I was able to go from a super slow speed (slower than 1 revolution in 10 mins (gear motor)) or the full 36V at maybe 200rpm. Vent systems also use VFD's, as at our school, if its really quiet, you can hear a pitch-sweep. Also, My motor was a universal AC/DC brush, if it helps to know.
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Actually, universal motor's speed is controlled by voltage as they are nothing more than series wound DC motors. VFD's are for induction motors which have only rotors with metal bars of either aluminum or copper embedded into the rotor surface and cannot work with DC (a VFD controller that accepts DC is needed to make AC motors work).

AC induction motor rotor (pic too large so made it a hyperlink):

http://upload.wikimedia.org/wikipedia/commons/f/fc/Wirnik_by_Zureks.jpg

Universal motor:

The reason the universal motor can run on AC also is because the field circuit and armature circuit switch their magnetic polarity together (they are wired in series to each other) when the AC changes it's polarity, thereby giving a net direction that is unchanged. Now if the field or armature circuit were a fixed magnetic polarity then the motor would just sit and a buzz at 60HZ like would happen if you hook up a permanent magnet DC motor to AC because the armature wants to rotate in a direction determined by the polarity of the AC, but at 60HZ that is not going to happen. so it is vibrating back and fourth.