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r2399
r2399
Visitor II
April 22, 2014
Question

'overlocking' L6470 / L6472

  • April 22, 2014
  • 3 replies
  • 801 views
Posted on April 22, 2014 at 14:31

Hi,

We have an application with a small steppermotor with only a small load. the current and voltage we use is way too high for the motor for longer periods of time, we only use it in short bursts.

The problem is that we cannot set the acceleration of the L6472 high enough. our stroke is only 2 turns and it never gets to its maximum speed.

Is there a way to increase the 'Tick' speed? 25 - 50% would be ideal for us.

Thanks,

Remco

#l6470-l6472 #l6470
This topic has been closed for replies.

3 replies

Enrico Poli
Enrico Poli
ST Employee
April 24, 2014
Posted on April 24, 2014 at 14:57

Hi,

It is not possible to change the tick time value. If you want to bypass the limits of the integrated motion engine you shoud use the step-clock mode.

Regadrs

Enrico

hof
hof
Associate
February 25, 2015
Posted on February 25, 2015 at 15:43

What is the maximum allowed frequency for the clock step mode (L6470, 128 uSteps)? Does the back EMF compensation work in this mode? If so, it would mean that the chip somehow measures the frequency and adjust the phase amplitude accordingly, right?

scope
scope
Associate
March 4, 2015
Posted on March 04, 2015 at 19:57

Remco,

ST employees seem to know nothing about this product.

I have the same application, a 40 oz*in NEMA 17 motor with a 3 oz*in inertial load and 1 step/second rate, intermittient, then up to 7200 s/s.

It is not possible to achieve that speed range with a fixed power supply on the L6472 board.

The main problem is the supply voltage and that youre probably using too high of a current level, and its the wrong board.

Do this:

1. Use the 6472 and set the Accel - Decel and Run currents equal, and at a very low value like 250 mA. Set the motor voltage to between 8 and 10Vdc for single step, or around 17V for 100 s/s, or choose a motor voltage value based on the V/Hz test to measure phase voltage at the desired step rate. Then choose the minimum operating currents that allows the motor to step. Then add a little current to make it stable.

2. Use the L6470, it is much more advanced than the 6472 and controls phase voltage and current (it controls phase current through controlling phase voltage unlike the 6472 which is a current limit scheme with fixed motor voltage.)

If the motor voltage is too low in either case, the motor cannot accelerate up to speed, may set an OC alarm and apparently that is what youre seeing.

You can do that, it just takes getting support and ST refuses to support us.

Sad./

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