I would like to use SnapAmp with stepper motors:
- how many microstep resolutions has SnapAmp (how to set it)
stepper motor has 200step/rev and I want set for example 12800 microsteps
- what current chopper frequency has SnapAmp?
- and what maximum step frequency can generate SnapAmp?
Best Regards
Albert
Group: DynoMotion
Message: 1652
From: Tom Kerekes
Date: 8/7/2011
Subject: Re: Snapamp question
Hi Albert,
SnapAmp works differently than a traditional Step/Dir Amplifier. To move a stepper motor smoothly the motor coils should ideally be excited with perfect sine and cosine current waveforms of a certain amplitude. KFLOP computes these currents with basically infinite precision every 90us and then sends the two values as two 13-bit values (for each motor) to SnapAmp. KFLOP refers to this technique as "Microstepper" output mode. In this mode a raw movement of 1 unit corresponds to 1 full sine wave cycle which corresponds to 4 full steps. A movement of 50 corresponds to one motor revolution. Realize that unlike with "steps" fractional units are allowed, so a commanded movement of 0.0001 cycle is allowed but may not effect a current change that is achievable by the amplifier (SnapAmp).
SnapAmp uses a fixed frequency 9-bit 30 KHz PWM with digital current measurement of 13-bit feedback to control the coil currents. This corresponds to a resolution of 7ma over a range of 60 Amps (+/- 30 Amps).
The max step rate would theoretically be 11,000 full steps per second.
BTW SnapAmp also is capable of driving a Stepper Motor as a Brushless DC motor if there is an encoder on the motor for feedback and commutation.
Regards,
TK
--- On Sun, 8/7/11, albertplatek <albertplatek86@...> wrote:
From: albertplatek <albertplatek86@...> Subject: [DynoMotion] Snapamp question To: DynoMotion@yahoogroups.com Date: Sunday, August 7, 2011, 7:10 AM
Hi Tom,
I would like to use SnapAmp with stepper motors: - how many microstep resolutions has SnapAmp (how to set it) stepper motor has 200step/rev and I want set for example 12800 microsteps - what current chopper frequency has SnapAmp? - and what maximum step frequency can generate SnapAmp?
