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| Driving 3-phase motor from 2 amplifier phases |
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| Kalin:
--- Quote from: duak on December 28, 2018, 01:47:23 am ---Kalin, I developed the analog and power sections of an ultraprecision BLDC motor system. Until the DSP portion with an encoder was completed, for testing I drove the motor with arbitrary frequencies. My experience is that a smooth ramp is required and the rate depends on the motor and its load. The motors I worked with might tolerate a 1 or 2 Hz jump, but not much more. When DC currents were applied to the motor, you could turn the motor shaft back and forth and it felt just like a spring. If you let it go, it would oscillate like a balance wheel in a clock. So while the rotor in the motor tends to follow the magnetic field generated by the windings, if they get out of sync, there's no net torque on the rotor and it slows down to a stop. Cheers, --- End quote --- Thanks for the insight. I work with VFD controlled motors alot but 1hp is a very small motor to me. Are BLDC motors typically permanent magnet motors or squirrel cage? Sent from my SM-G965W using Tapatalk |
| Psi:
Look at brushless DC speed controller schematics. They're more or less a MCU and 6 mosfets |
| Circlotron:
--- Quote from: Benta on December 27, 2018, 08:29:46 pm ---I look forward to seeing your sim, this sounds strange. --- End quote --- This shows that my three voltage sources are 120 deg apart with respect to neutral. |
| Circlotron:
And with the ground shifted to the B phase, showing the difference in phase between B-A and B-C is 60 deg. |
| Dave:
--- Quote from: Kalin on December 28, 2018, 01:51:43 am ---Are BLDC motors typically permanent magnet motors or squirrel cage? --- End quote --- Motors with squirrel cages are induction motors. BLDC motors always have permanent magnets inside. |
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