# High Voltage AC motor for an Electric Bike?



## electro wrks (Mar 5, 2012)

The motor you have and the one from amazon are single phase induction motors. They're not practical for vehicle use. 3 phase induction motors will work. But, commercially available ones require too high a voltage to be practical, are sometimes RPM limited, and can be very heavy. This company builds commercial frame, 3 phase motors for EV's: http://www.hpevs.com/ . They're probably bigger than what you're looking for. They're made for lower voltages, higher currents, and much higher RPM for a higher power to weight ratio. But, they require an expensive, specialized controller and won't be showing up on amazon or eBay for $129.00 for a long, long time.

The other motor is a basic permanent magnet brushed motor (that's a good price BTW with free shipping). It's probably too small for a motorcycle, but when properly geared down, it could propel a bicycle to 20-30 MPH(~30-50kph) on the flat. The controllers can be had for <$60.00:http://www.ebay.com/sch/i.html?_sacat=0&_nkw=48+v+motor+brushed+controller&_frs=1 

The other main type of motor is the brushless type. In the past, most of these were hub motors. Now, it looks like there are some stand alones available too: http://www.ebay.com/sch/i.html?_odk...+motor&_nkw=48+v+brushless+motor&_sacat=48446

The main expense will be the batteries http://www.ebay.com/sch/i.html?_odk...hium+ba+&_nkw=48v+lithium+battery&_sacat=7294 And: http://www.ebay.com/sch/Multipurpos.../i.html?_from=R40&_nkw=48+v+lithium+batteries


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## Sunking (Aug 10, 2009)

This will sound stupid, but why not just use one of the 36 to 72 volt DC motors made for bikes?


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## PStechPaul (May 1, 2012)

If you already have a 120 VAC single phase induction motor, it is possible to rewind it for three phase, and a lower voltage. If the stator has 24 slots, it can be made up to 8 pole, and 36 slots can be 12 pole. Theoretically, you could overclock it up to about 4x (240 Hz) and get higher power and still be under the safe speed limit of about 4000 RPM. 

Once you have a 3 phase motor, you will need a VFD to control it properly. It may be possible to program a 208/240V industrial VFD to drive a 60V motor at 60 Hz and go up to 240V at 240 Hz. But you would need to disable the low voltage dropout of the VFD from the usual 200V to 40V to use a 48V battery. But you would lose the higher torque and power if you used overclocking.

So, you really need about 200-300 VDC to supply the usual DC link in the VFD. Actually this is not all that difficult. I bought a 24 VDC to 220 VAC 1500W automotive inverter (about $60), and I connected to the internal 240 VDC supply, which was enough to power my 2 HP VFD and it was able to spin a 2 HP 2 pole three phase motor, from two small 12V batteries. I also built my own DC-DC converter, and I'm working on another, more efficient design.






This shows a 12V 1000W inverter:





Later I got this one but I have not actually used it on my vehicle:










This is the internal connection to negative. The 240 VDC positive is on the other side of the PCB:










Here it is hooked up to a 24 VDC supply after adding internal connections:










Even if you decide to use a DC motor you could use an inverter like this to boost 12V or 24V to 135V and a PWM controller for a 90V motor which is often found in treadmills.


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