Re: [CAD_CAM_EDM_DRO]Thanks. Was: Phase Drive Control?

Thanks for the replys. A little knowledge is a dangerous thing and
I have as little knowledge as anyone - but my wife says I'm only
a danger to myself. :-)

Bob


At 10:32 AM 9/4/00 -0700, you wrote:

>
>Bob,
>
>The 4-phase drive is simply individual control of the four "leads" of a
>unipolar stepper motor. The driver in this case (MAXNC's low end
>package, for example) has four darlington TIP 120 transistors for each
>axis. think of it as a "low level" interface.
>
>Step and direction (S&D) is a "higher level" interface. Drivers must
>take these two signals, walk a counter (step) through four (full step),
>or eight (half step) counts, and decode when and which motor lead(s) to
>turn on. The direction tells the counter which way to count. The
>driver can drive unipolar or bipolar stepper motors, depending on its
>design.
>
>Unipolar (I knew you'd ask that) may be simply thought of as four
>windings, all with one end connected together, and one winding at a time
>turned on to make the motor step. Bipolar brings out two pairs of
>windings. In this case, each winding can be energized (driven) in two
>directions. In the simplest case, there are therefore four possible
>combinations of driving the windings. It gets more complicated after
>that. half step and other "micro step" implementations (more advanced)
>engage more then one winding at a time (often with overlap, hence more
>states), and even various levels of drive to achieve micro steps of 10
>or even 256.
>
>Other drivers (still more advanced) are "chopper drives", which use high
>voltages to get the di/dt's up on the windings (overcomes the
>inductance), instead of our simple unipolar 4-phase example, which uses
>a 10 ohm resistor, a 24v motor, and a 24v transformer. Choppers may use
>80v power supplies and 2v motors!
>
>For further information, check out Jones:
>
> http://www.cs.uiowa.edu/~jones/step/
>
>Hope this helps.
>
>Alan
>
>Robert Bachman wrote:
>> Will someone please explain 'Phase Drive Control' as opposed
>> to 'Step & Direction'? I know what step and direction is.
>>
>> Thanks,
>> Bob
>>
>
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