Greetings,
I own a Nova 3000 DVR lathe, and I've just bought a used DVR XP that I'll take delivery of next week. I plan to use the DVR XP as a bowl lathe, and dedicate the old 3000 DVR (as it has now been extended to take ~1.2 meters between centres) for long spindle turning work.
As a curious person, I'm always interested in knowing how the machinery that I own actually works - it makes things much easier to diagnose when something goes wrong with the machine. In Teknatool's own documentation, there is only a very simplistic explanation of what the DVR (Digital Variable Reluctance) motor is. A call to Teknatool's telephone support line gave me only a repeat of the marketing blurb that is in their documentation and on their web site - plus the statement that "some parts of the DVR Motors are patent protected".
From examining the parts breakdown diagrams for the DVR Motor, the rotor apparently has permanent magnets embedded in it, and no brushes or wiring. The field coils are only drawn as a basic sketch in the parts diagram, so there's not much to be gained there. From that information, I don't think that it can be a 3 Phase AC Motor with a VFD driving it. I'm guessing that it might be a brushless DC Motor with multiple field coil poles, driven by pulse width modulation.
But the brushless DC Motor explanation doesn't seem to account for some of the additional features, such as the fact that at low speeds (e.g. 200 - 300 RPM), when you place the cutting tool onto the work piece, and load the motor up, you can hear the motor sound change, and the speed remains constant. And, on the two occasions when I've had a bad catch, the DVR Motor instantly shut down, so there must be some sensing involved to determine that there was a catch.
So, can anyone with a technical background in electric motors and/or electric motor speed control technology, provide a technical explanation of how Nova's DVR Motors work ?
Thanks,
RoyG
I own a Nova 3000 DVR lathe, and I've just bought a used DVR XP that I'll take delivery of next week. I plan to use the DVR XP as a bowl lathe, and dedicate the old 3000 DVR (as it has now been extended to take ~1.2 meters between centres) for long spindle turning work.
As a curious person, I'm always interested in knowing how the machinery that I own actually works - it makes things much easier to diagnose when something goes wrong with the machine. In Teknatool's own documentation, there is only a very simplistic explanation of what the DVR (Digital Variable Reluctance) motor is. A call to Teknatool's telephone support line gave me only a repeat of the marketing blurb that is in their documentation and on their web site - plus the statement that "some parts of the DVR Motors are patent protected".
From examining the parts breakdown diagrams for the DVR Motor, the rotor apparently has permanent magnets embedded in it, and no brushes or wiring. The field coils are only drawn as a basic sketch in the parts diagram, so there's not much to be gained there. From that information, I don't think that it can be a 3 Phase AC Motor with a VFD driving it. I'm guessing that it might be a brushless DC Motor with multiple field coil poles, driven by pulse width modulation.
But the brushless DC Motor explanation doesn't seem to account for some of the additional features, such as the fact that at low speeds (e.g. 200 - 300 RPM), when you place the cutting tool onto the work piece, and load the motor up, you can hear the motor sound change, and the speed remains constant. And, on the two occasions when I've had a bad catch, the DVR Motor instantly shut down, so there must be some sensing involved to determine that there was a catch.
So, can anyone with a technical background in electric motors and/or electric motor speed control technology, provide a technical explanation of how Nova's DVR Motors work ?
Thanks,
RoyG
Can Anyone Provide A Technical Explanation Of How Nova's DVR Motors Work ?
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