generate 3 phase delta?

This is a four pole hysteresis synchronous mortor, B-2700 series. It runs at

1800 RPM on 60Hz single or three phase, 115VAC. It gives one ounce-inch of torque at 1800 RPM, 12 watts.

To run single phase connect the AC line to the Blue and Green leads. Connect a 2uF, 200VAC capacitor between the White and Green leads. To reverse direction, connect the capacitor between the White and Blue leads.

A hysteresis synchronous motor does not have permnanet magnets nor is it an induction motor. The rotor is iron and assumes a permanent magnetic flux when energized. There are no fixed poles on the rotor. The rotor will lock onto sychronous speed of the rotating field, in this case 1800 RPM. These motors are used where accurate rotational speed is required but they don't give much torque. Bob

You will need some source of 3 phase power (3 sine waves, each shifted

120 degrees with respect to the other two) at the appropriate volts per hertz (higher frequency requires higher voltage) capable of the required current. Each winding runs on the voltage difference between two of the phases.

With the correct voltage to frequency ratio, it can run over a wide range of frequency. I don't know if that model is a permanent magnet synchronous type or an induction type.

BE: This is a four pole hysteresis synchronous mortor, B-2700 series. It runs at

1800 RPM on 60Hz single or three phase, 115VAC. It gives one ounce-inch of torque at 1800 RPM, 12 watts. To run single phase connect the AC line to the Blue and Green leads. Connect a 2uF, 200VAC capacitor between the White and Green leads. To reverse direction, connect the capacitor between the White and Blue leads. =================================== Hi Bob. I saw where one could run it from single phase with a cap.... but I wanted to see if I could drive it with a microcontroller somehow...wondering how to generate 3 phase. I noticed it put out a sin wave between any pair of wires.... that's why I thought it had a perm magnet in it. Sounds like a lot of work. There's a dozen or so of em at Skycraft.

BE: This is a four pole hysteresis synchronous mortor, B-2700 series. It runs at

1800 RPM on 60Hz single or three phase, 115VAC. It gives one ounce-inch of torque at 1800 RPM, 12 watts. To run single phase connect the AC line to the Blue and Green leads. Connect a 2uF, 200VAC capacitor between the White and Green leads. To reverse direction, connect the capacitor between the White and Blue leads. =================================== Hi Bob. I saw where one could run it from single phase with a cap.... but I wanted to see if I could drive it with a microcontroller somehow...wondering how to generate 3 phase. I noticed it put out a sin wave between any pair of wires.... that's why I thought it had a perm magnet in it. Sounds like a lot of work. There's a dozen or so of em at Skycraft.

Yes you could generate three phase signals in a microprocessor. You'd have to run the motor on higher voltage, however, 115 volts for 60Hz. You could run at higher speed (frequencies) with higher voltages and lower speeds with lower voltages. The volt-time product per cycle is held constant for variable frequency drive. The frequency varies the speed and the constant volt-time product keeps the torque controlled without allowing the motor to overheat at low speeds. Usually such drives use pulse width modulation to generate sinusoidal currents for the windings. Again a microprocessor could easily develop the required three PWM switching signals for a three phase system. The PWM signals would also incorporate the necessary constant volt-time product characteristic. The drive elements for the motor could be FETs or IGBT's or power transistors all driven from the processor. It sounds like a big deal though just for a one ounce-inch motor. Such variable frequency inverter drives are used on all kind of motors from fractional HP on up. Bob

Generating 3-phase in a uC isn't hard at all - just have three look-up tables of 3 sine waves 120 degrees out of phase from each other, and run 3 DACS to give you the three phases. Or, you could use one LUT and three scrolling indices 1/3 of the way apart from each other, but that'd be nasty ugly because your LUT would have to be 3N entries long. ;-) You probably wouldn't need very big look-up tables; it's surprising how quickly harmonic content drops off with just a few samples.

That also gives you absolute speed control, without relying on a cap, but mind what John Popelish said about making the drive voltage inversely proportional to the frequency. (at least, I _think_ that's what he said - it's been a couple of posts ago. ;-) )

I don't know how to turn three, ground-referenced outputs into a delta, however. I wonder what would happen if you just used three half-H's, which, I guess, amounts to 3x totem-pole outputs? My intuition says, "of course", but I haven't done the grunt work yet.

Good Luck! Rich

possibly there's no magnet but a rotor that picks up a current from the magnetic field of the windings and behaves a bit like a magnet - google for induction motor,

Bye. Jasen

it may be possible to drive only two of the inputs (and ground the third). the two driven inputs should have a phase difference of 60 degrees.

bear in mind that with this setup the driven inputs have nearly twice the voltage from the undriven input than they would have from ground if being driven from a three phase supply... so check the winding to frame insulation in that datasheet before trying that with the undriven input grounded.

Bye. Jasen