Puzzled by a stepper motor

• Oct 2, 2011

• #1

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bobsun

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Hi,

I would like to ask a question on stepper motor.

I have recently bought a new permanent magnet stepper motor. According to its datasheet, it requires two poles to be driven simultaneously to rotate.

I was not able to figure out its internal magnet and electric pole structure. Could anyone infer it out?



Bob

 

• Oct 2, 2011

• #2

alexan_e

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It is a standard bipolar motor Stepperworld Bipolar Tutorial

Also take a look at **broken link removed**

Alex

 

• Oct 2, 2011

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prmurthy

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I am assuming that you are asking of how to the stepper motor works. If my assumpsions are wrong please forgive. Here are some links for types of stepper motors.

**broken link removed**
http://www.solarbotics.net/library/pdflib/pdf/motorbas.pdf

Hope it will be of some help to you.

 

• Oct 2, 2011

• #4

bigdogguru

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The following is one of the most comprehensive tutorials on stepper motors available online:

**broken link removed**

Do you have the datasheet for your stepper motor? What is the make and model?

BigDog

 

• Oct 2, 2011

• #5

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bobsun

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Alex,



If you look at the two examples of "Half stepping" in the "How Stepper Motors Work" link, either for one-coil or two-coil excitation, through the steps the number of poles that are being excited is are not constant. It changes in a pattern like "1, 2, 1, 2".

But for the motor I encountered, the datasheet requires at all four steps driving two poles, although with direction change. I was not able to figure out its internal structure.

Is there any one help able to dissect it by analyzing?

Bob

 

• Oct 2, 2011

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bobsun

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prmurthy,

In you linked PDF I found the following example:



I don't under how "Normal full step" in the example works. Is there any animation for that?

Bob

 

• Oct 2, 2011

• #7

FvM

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It's a simple full step pulse scheme, which can be driven either to one (called "wave drive" in your scheme) or two coils ("normal" full step). Driving both coils results in slightly lower copper losses due to a higher duty cycle. If you sketch the flux vector, it's still rotated by 90 degree (electrical) steps.

 

• Oct 2, 2011

• #8

alexan_e

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See

You are using

Terminal 1a + + - - + + - - + + - - + + - -
Terminal 1b - - + + - - + + - - + + - - + +
Terminal 2a - + + - - + + - - + + - - + + -
Terminal 2b + - - + + - - + + - - + + - - +

You change the polarity of one coil in each step, this is full step drive

Alex

 

• Oct 2, 2011

• #9

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prmurthy

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bobsun said:

prmurthy,

In you linked PDF I found the following example:

View attachment 62154

I don't under how "Normal full step" in the example works. Is there any animation for that?

Bob

Click to expand...

Bob please co-relate with your image that yo have provided in the begning. Both are same. FvM has explained.

 

• Oct 2, 2011

• #10

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bobsun

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FvM,

I got it, thanks.

Bob

---------- Post added at 22:44 ---------- Previous post was at 22:43 ----------

purmurthy,

I could run it with full-step now, thanks.

Bob

 

• Oct 2, 2011

• #11

bigdogguru

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How are you driving your stepper motor, with MCU or dedicated driver module?

BigDog

 

• Oct 5, 2011

• #12

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bobsun

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bigdogguru,

Sorry for my delayed response.

I am driving motor with a MCU, and is in full-step mode. There is a L298N H-bridge to control the current direction.

Bob

 

• Oct 5, 2011

• #13

bigdogguru

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I was just going to suggest some tutorials based on the driver method, but it appears you may have already figured it out.

If you are still looking for insight:

Stepper Motor Control: Introduction

L298 Stepper Motor Control: Introduction



Bi-directional Control Of Motors And The H-Bridge

The last link above contains some useful algorithms for braking, ramping, etc.

BigDog

 

• Oct 5, 2011

• #14

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bobsun

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bigdogguru,

Thanks for the links. I will have a look at them.

Bob