The Structure and Principle of the Number of Stator Phases

1.Single phase stepper motor
The single phase stepper motor is winding a loop coil on a coils framework, giving it a positive and negative alternating current, and each switching current takes a step in a fixed direction. Because the magnetic conductance of the rotor magnetic path become bigger to change the rotation direction, the single phase stepping motor can only move in one direction, so a single phase stepper motor just only moves in a one direction. In order to ensure the fixed rotation direction, the magnetic conductance takes many measures, for example, to make the stator air pole wider than the rotor, and the working air gap between the stator and rotor is not uniform, and the direction of rotation is in the direction of small reluctance.

https://www.oyostepper.com/goods-45-Nema-Size-17-Stepper-Motor-Bipolar-45Ncm-64ozin-2A-42x40mm-4-Wires-w-1m-Cable-Connector.html

2.Two phase stepper motor
The simplest structure of the two phase stepper motor is that Nr=1, Generally ,the number of the stator magnetic pole is a multiplier of 4, at least 4. The rotor is a two pole rotor with one at N pole and one at S pole.

3.Three phase stepper motor
The stepper motor, of which does not use permanent magnet on its rotor, is very early used on three phase stepper motor. In 1986, a Japan servo company developed a stepping motor with permanent magnet and stator magnetic pole with gear, the matching of stator and rotor pitch can achieve higher angular resolution and torque. The main pole number of the stator winding of the three phase stepping motor is multiples of three, so the stator main pole number of the three phase stepping motor is 3, 6, 9, 12 and so on.


4.Four phase stepper motor
According to the formula θs=180°/PNr, if Nr=50, θs=0.9°，then P=4，that is four phase stepper motor. Because of the even phase of the four phase step motor, the power pipe of the driving circuit is 16, the number of the main pole of the stator is 16, all of which are two times of the two phase stepper motor, so the drive structure is complicated and the cost is high, so it is only used for special purpose.

5.Most of stepper motors sold on market are are five phases. 
The stator structure and drive circuit are simpler than the four phase stepper motor, but more complex than the two phase and three phase stepper motors and the cost is high.

The Latest International Stepping motor sizing and NEMA standards

HOW TO READ INPUT VALUE FROM STEPPER MOTOR ENCODER

You will need :

Motor with encoder

Arduino board ( I used arduino Uno)

Computer

Battery or DC voltage supply

Encoder library , download from https://www.pjrc.com/teensy/td_libs_Encoder.html or from the zip file attached

Background : https://en.wikipedia.org/wiki/Rotary_encoder

( A little experiment I did with multimeter :

power the encoder with 2 AA battery, attach multimeter GND cable to GND of the battery , and multimeter RED cable to the C1 or C2 output of the encoder.

As you turn the motor slowly, you can see that the output voltage of C1 and C2 change from 0V to 3V.

If you have 2 multimeter, attach C1 and C2 each to a multimeter, then turn the multimeter slowly you can see the value of multimeter change from 3V-3V, 0V-3V,0V-0V,3V-3V, which is the pulse according the background theory).

Step 1: Wiring

The DC motor with encoder has 6 wires :

2 wires to power the motor (Often labeled as : M1, M2 , motor power ...)

2 wires to power the stepper motor with encoder (often labeled GND and 3.3V)

2 wires to send signal of position to the microcontroller (Arduino) (labeled as encoder output or C1 & C2)

First you will connect 2 wires to power the encoder to Arduino Gnd And Vcc 3.3V (in my version of encoder motor, the encoder led turn on when I connected the wire power)

Then connect 2 wires signal of the encoder to 2 pins with interrupt of Arduino , (which is pin 2 and 3 of the Arduino Uno)

You can turn the motor by hand or connect 2 motor wires to the battery to rotate the motor.

Note : normal pin will still work at low speed when you turning the motor by hand, however, when you run the motor with the battery and the motor rotates at high speed, the encoder will misread the position of the motor, result in duplication while reading. Using interrupt pin with the library prevent the encoder from making this mistake (in my experiment it was quite accurate when read the motor with interrupt pin, the only time it make a mistake is in the end when I stop the motor and the motor slowing down, that time the reading was duplicate for a few position).

Step 2: Upload the Code:

After the installed the library, you can open File/Example/Encoder/Basic to run the code , or copy paste this code in :

/* Encoder Library - Basic Example

 * http://www.pjrc.com/teensy/td_libs_Encoder.html

 * This example code is in the public domain.

 */

#include 

// Change these two numbers to the pins connected to your encoder.

//   Best Performance: both pins have interrupt capability

//   Good Performance: only the first pin has interrupt capability

//   Low Performance:  neither pin has interrupt capability

Encoder myEnc(2,3);

//   avoid using pins with LEDs attached

void setup() {

  Serial.begin(9600);

  Serial.println("Basic Encoder Test:");

}

long oldPosition  = -999;

void loop() {

  long newPosition = myEnc.read();

  if (newPosition != oldPosition) {

    oldPosition = newPosition;

    Serial.println(newPosition);

  }

}

Step 3: Results

After successful with all above step, turn on the serial monitor :

And first turn the motor with your hand to see that the position is slightly change

Then run the motor with battery to see that position reading change rapidly as the motor run fast.

I hope you find this helpful. Thanks for reading. If You have any question about stepper motor, you can visit our website :oyostepper.com for help.

Practice on Controlling a Stepping Motor

In our article about stepper motors we have presented this type of electric motors, how they operate and what makes them highly compatible with digital control systems. Now we will talk about how to control such a motor together with a simple example, involving a H-bridge electronic circuit and simple scripting. In our implementation we have used a bipolar 23 stepper motor, however minor changes in control sequences are required for other types of stepper motors.

To summarize, the electromagnetic coils are located on the stator of the stepper motor, while permanent magnets, equal in pair numbers, are located on the rotor. A more detailed discussion about stepper motors can be found in our dedicated article, but making a long story short, like any DC motor, these motors rotate when the coils are energized however, if the coils are continuously energized in the same way, the movement will stop when opposite magnetic poles are aligned, e.g. S-pole on coil aligned with N-pole on rotor permanent magnet.

Electromagnetic coils found in a bipolar nema 17 stepper motor are arranged as independent windings, each of them corresponding to one phase. Usually such stepper motors have 6 terminals, 5 if the common wires of the two windings are internally connected, and the terminals can be identified by measuring the resistance between terminals using a multimeter.

In short, if resistance of a coil, between its two end terminal has a certain value, the resistance between the common lead and any of its terminals must a value divided by 2. In 5-lead motors, coil terminals can be determined by touching each two wires together. When the rotor shaft becomes harder to turn it means that the two connected wires belong to the same winding.

See more:

https://forum.shapeoko.com/viewtopic.php?f=4&t=1409&p=69838

https://www.v1engineering.com/forum/topic/closed-loop-motor-control/

The difference of analog and digital drives

Faster and cheaper processors currently being turned out by the silicon foundries are making it easier to justify digital stepper motor driver instead of traditional analog drives. But do digital drives offer a clear advantage for more applications?

Compare the two approaches by first analyzing the classic analog drive shown in the diagram. In this case, the drive is configured as a torque amplifier. An external controller generates a ±10-Vdc command signal. The drive monitors the motor winding current and estimates the mechanical torque. A compensator takes the difference and generates a voltage command signal. Next, a pulse-width-modulated signal is applied to an inverter, which switches the correct voltages to the motor.

One of the main advantages of a digital drive system is the ease with which new features can be added. If it has sufficient processing power, additional functions can be added for only the cost of development. For example, consider the active damping feature first introduced on steppers. The analog drive circuitry required more than 100 components. Obviously, this had to be accounted for early in the design. When the active damping feature was implemented in the digital drive, it merely consisted of several lines of code. With sufficient processing power, features such as encoderless stall detection, which would be nearly impossible to do in analog, can be economically added to the drive.

Another advantage of a digital drive is the ease with which it is field upgradable. Using flash memory, new software can be posted on a Web site or e-mailed to customers. This lets new features and bug fixes be easily delivered to the field without sending the drive back to the factory. Custom software specifically tailored to a single customer's application is also possible.


Although analog stepper driver for sale are typically less expensive than digital ones, the controller often is integrated into the digital drive, which can reduce overall system cost. Analog drives are also easier to set up, with DIP switches being set rather than having to program the parameters so initial motion profiles can be generated quickly. However, digital drives offer more parameter variations, which lets system designers have more options.

Stepper motor types and operation

3X MOTION Hybrid Stepper Motors NEMA 24 For Medical USE

3X MOTION Hybrid Stepper Motors NEMA 24 For Medical USE

Description                          

                           

3X MOTION Hybrid Stepper Motors SALE are widely used in laboratory and medical equipment, printing machines, pumps vending machines and a multitude of other applications.                          

                           

Customization Options                          

                           

Custom Shaft & Mounting Details:

All NEMA 24 motors can be supplied with single or double ended shaft to customer request shaft length and other dimensions can also be modified on demand.

Number of Leads:

All motors can be supplied with 4, 5, 6 or 8 leads and if required a connector can be provided on our motors to customer request

Winding code:

Since each customer request can be different, we list only our standard products in this catalogue. However, we will be happy to quote other variants to your request.

Holding Torque:

Holding torque is measured with two phases supplied at the rated current. The enclosed technical specifications are therefore typical.

(On customer request for special shaft, leads, fixings, etc. We will provide you with a unique product code/identifier)

Applications:

• security, 
• textile, 
• medical, 
• 3D printing, 
• communication,
• solar etc.

What Should I Select Bettween NEMA 23 and NEMA 34 motor

Advantages and disadvantages of stepper motors

Advantages:
1. Step angle of stepper motor is proportional to pulse rate.
2. Stepper motor outputs its maximum torque at the moment it stops running (when winding excitation).
3. the precision of every step is controlled within the range from 3% to 5%. Plus, the error in the last step won’t be accumulated intothe next step; the stepper motor has very good position precision and good movement repeatability.
4. Excellent start-stop and reversing responses.
5. As stepper motors are brushless ones, the lifetime of stepper motor is determined by the bearings' lifespan only.
6. The response of the motor is only determined by the digital input pulse. Therefore, open-loop control can be adopted. So, theconfiguration of stepper motors can be comparatively simple. The manufacturing cost is low.
7. Synchronous rotation at ultra-low speed can be actualized when the load is coupled with the shaft of stepper motor.
8. As the speed is proportional to the pulse rate, a wide speed range can be avaliable.

Disadvantages:
1. Once stepper motor is out of control or under inappropriate control, resonance is apt to be generated.
2. Comparative high speed is not easy to be achieved.
3. Comparative high torque is not easy to be achieved either.
4. Stepper motor has no advantages in aspects of size and weight. Energy utilization ratio is comparatively low.
5. When overloading, the synchronization will be broken. Vibration and noise occur when running at high speed.

 Source:https://www.oyostepper.com/article-1085-Advantages-and-disadvantages-of-stepper-motors.html

how do you actually control and run a stepper motor?

But how do you actually control and run a stepper motor? There are two modes that can be used to operate a stepper motor: unipolar and bipolar mode. Unipolar mode only operates in the positive voltage range. Normally, this would mean that current could only be driven in one direction through the electromagnetic coils, producing a magnetic field in only one direction, implying that the central shaft would only be able to tilt back and forth between the two electromagnets.

This potential issue is overcome by the fact that unipolar hybrid stepper motors actually have an additional wire attached to the middle of the two coils. This allows current to flow in two different directions, from the middle to one side of the coil or to the other side of the coil. These two directions produce magnetic fields in the “opposite” directions, allowing the teeth of the magnetized central shaft rotate a full 360 degrees.

Bipolar stepper motors also have current flow in two different directions through the coils. Instead of using a central tap, they use both positive and negative (bipolar) voltage to induce the current flow in both ways through the coil. Because current is able to flow through the entire coil, instead of just half of the coil in unipolar mode, bipolar stepper motors have more torque to rotate and hold the central shaft in place.

How do you know if your stepper motor is a unipolar or a bipolar stepper motor for sale just by looking at it? In most cases, the motor you are looking at is both. Unipolar and bipolar are just modes that you can use to run the stepper motor. The only time a stepper motor is not able to be run in either mode is when there are only four wires coming out of the stepper motor, corresponding to the both ends of the two coils and no central tap wire.