Stepper motor driver help

[Brian AbbottParticipant @brianabbott67793]

Hello all

Could someone offer me some guidance on setting up a stepper motor driver.

On the one i have bought it uses switches to control the current, there is also an option for half or full.

Can anyone explain how i would need to set this up?

I am driving a Nema 23 motor using a CW5045 driver.

Thanks for any help.

[Brian AbbottParticipant @brianabbott67793]

[Martin ConnellyParticipant @martinconnelly55370]

This site has instructions. It says that current is halved if no signals are received for a few seconds to reduce power use and heating of the motor. I presume the switch allows having this feature operate or not. Should be checkable with a multi meter to find out which way does what.

CNC4U resources

Martin C

Edited By Martin Connelly on 21/05/2020 19:06:47

[Brian AbbottParticipant @brianabbott67793]

Thanks Martin,

but unless i am missing something it does not tell you which current setting to use, only the options.

[mgnbukParticipant @mgnbuk]

I am driving a Nema 23 motor

Nema 23 is the frame size of the motor – to set up the drive you will need to know the electrical characteristics of your particular motor and in particular the phase current. This varies according to the motor output & windings & is independant of the frame size, though they seem typically to be between 3 and 4.5 amps for Nema 23 motors. Can you post a link to your specific motor ? It is the phase current of the motor that tells you what the switches on the drive need to be set to. If you set the current to less than the rated value the motor will not develope it's rated torque – set it too high and you risk overheating the motor.

The full/half current setting is for the standstill current – when the drive has not received step pulses for a while, this setting detremines if the current is maintained at the full value while the motor is stationary, or reduces the current by half. This can reduce heat build up in the motor at standstill, but does so at the expense of holding torque which reduces with the current reduction. This may be important if the axis could be moved out of position with a lower standstill torque.

Nigel B.

[Brian AbbottParticipant @brianabbott67793]

Hello Nigel,

This is the motor.

**LINK**

[mgnbukParticipant @mgnbuk]

Hi Brian,

The data sheet shows 4.2A phase current for that motor when parallel connected. The motor wires need to be connected in the "bipolar parallel" arrangement shown at the bottom of the data sheet.

The drive you mentioned shows a 4.2 amp setting for the current switches – set SW1 to ON, with SW2 & SW3 set to OFF to get this.

HTH

Nigel B.

[Iain DownsParticipant @iaindowns78295]

The data sheet indicates that it can be used in unipolar or serial or parallel bipolar mode..

The current to set varies between 2.1A and 4.2A depending on how you have wired it up. I would guess you're using it in bipolar mode so if some of the wires on the motor join only to other wires on the motor it's in series (2.1A) if they are connected together in pairs (and from there to the driver) it's in parallel mode, so 4.2A.

You can set to less, of course but you will lose power and speed.

Iain

[John HaineParticipant @johnhaine32865]

I suggest you ignore unipolar mode.

[John HaineParticipant @johnhaine32865]

So why would you choose parallel or serial connect? IIRC both give the same torque but parallel better top speed/acceleration at the expense of larger drive and therefore supply current. If your PSU can supply 4.2A then use parallel.

I may misremember though!

[Brian AbbottParticipant @brianabbott67793]

The motor will be wired as parallel so i will set it as 4.2 amps.

Thanks for the reply’s and thanks Nigel for the clear explanation.

[mgnbukParticipant @mgnbuk]

The general suggestion when there is an option seems to be to use bipolar parallel operation for best overall performance. As the drive will handle the bipolar parallel current, why go for series operation ?

When I bought the motors & drives for my Triac from Arc Eurotrade many moons ago, I went for 3A drives as i could not run to the larger versions at the time. The motor data sheet showed similar current values to the Op's motor (4.2 bipolar / 2.1 series) but these are rated 2.2Nm. The motors did work after a fashion using these drives in series connection on a 24v supply, but performace was "pedestrian". Note that this was on the bench, not driving the machine,. The same motor in bipolar mode driven from a Stepper Online digital drive at 36V is night and day different under the same testing conditions. I have yet to try this drive a with the 48V supply I recently received.

Nigel B.

[AdrianRParticipant @adrianr18614]

In the CW5045 wiring diagram on the linked page it shows the motor being wired in parallel and what colour wire goes where.

Adrian

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