Hello. 1
In this video we are going to learn stepper motor basics. 2
The Stater of the stepper motor consists of electromagnet poles on which the coils are wound. 3
You can see it in this picture. 4
There are iron core natural magnet dislocated poles in the rotor so in the right side you can see stepper 5
motor driver an example. 6
And in here also you can see an example picture of stepper motor in the figure below in here. 7
The basic principle and Operation principle of the stepper motor are described coils are wound on six 8
pole A C B A C B but we can think it this is A this is not A this is B. 9
This is not B this is C this is not C or inverted. 10
We can think it like this the connection of this coils is made to form the N S pole pair mutually. 11
There are four dislocated poles on the rotor so the rotor is here. 12
You can see the numbers 1 and 2 and 3 and 4. 13
So we are going to see these rotor is going to turns and Stator is not turned and 14
there is no movement for the stator ,stator is fixed one the rotor is going to turn rotor can turn 15
rotor can move so the next page we will see when the pair A is energized it will bring the nearest 16
rotor dislocation pole to the same axis by pulling it to the Pole level. 17
So what is happening when A is energized. 18
So okay this moment this is our stator and this is our rotor position. 19
An example after A let's energized coil B when B is energized. 20
So this rotor goes this side you can see now the first time two rotor two position was here. 21
Middle of the c and b and b energized or activated B pole so two is turn 30 degree to right side 22
30 degree. 23
How can we know it. 24
Because . 25
Now in the first position two was between C and B two. 26
pole is just came from this to here. 27
Also the same movement happened for here it was the A position from A position one turn 30 degrees 28
to the right side and if we energized C pole what happens when the C pole is energized that moment 29
one position turns a little bit right and it pulls to rotor two itself to C pole 30
So one 30 degree movement happens again. 31
So when the c coil energized after B coil the rotor pole three and one will move another 30 degrees 32
forward to pole C this time. 33
And if coil A energized again after coil C this time 2 and 4 rotor poles will be aligned to A pole axis. 34
So if you noticed a and b and c coils provide sequential energy and the 30 degree motion of the rotor 35
is provided. 36
If this switching is continued always than 30 degree 30 degree 30 degree 30 degree and in the end 37
after a twelve movement one turn will be existed so they will get rotational movement like this. 38
if our switching sequence is made in reverse as C B and A so how we will turn to counterclockwise 39
direction we will turn like this an opposite direction rotational movement will exist. 40
The number of stator pole must always be different from the number of rotor Poles otherwise rotational 41
movement will not start for stepper motors. 42
Also you can see in here some examples pictures and we can get one point eight degree movement 43
also with stepper motors. 44
The main features of stepper motors the angle of rotation is proportional to the number of input phases 45
phases. 46
This is really important and also the rotation speed is proportional to the input phase ratio to phase 47
frequency 48
We can call it like this. 49
Then torque can occur on their own because a permanent magnet is used for inside of the stepper motors. 50
Stepper motors has high torque and good result and lightweight and they are working with the 51
small angles with the high efficiency and the stepper motors are cheap and also there is no need for 52
maintenance because it's a brushless DC motors. 53
How many types stepper motors that we have. 54
There are three main types of stepper motors permanent magnet hybrid synchronous and variable reluctance 55
stepper motors and also in this picture you can see the poles X and not X Y and not Y and the Poles 56
positions in here and in here we have our rotor and for the rotational movement we will energize X 57
and Y and Y and X not and X not and Y not. 58
Y not an X then we will get one turn rotational movement then if we energized continuously at our stepper 59
motor is going to turn. 60
Always at the stepper motor drivers at least two information must be known by the driver. 61
This is really another important point. 62
The first of these switching pulses. 63
So step the switching pulses means the steps so the driver switches the motor coil sequentially in 64
each pulse coming to it. 65
So this information also determines the switching frequency like motor speed. 66
Step information can be given from the plc or control unit or programming the oscillator or driver 67
an etc. to the stepper motor driver and another information must be no. 68
And this information is direction information. 69
And this is digital input and it's reserved on the drive. 70
So if this input is 1 equals 1 or high the motor will rotate one direction. 71
And if this input is zero or low the motor is going to turn another direction during the switching of 72
coils of the stepper motor. 73
The reverse induction voltages will occur due to inductive property of the coils. 74
If we are running our motor over the driver or if we are using a driver or drive for the stepper 75
motors the manufacturer has taken the necessary measures on the driver switching floor. 76
If however we must prevent this reverse induction voltage created by connecting our motor by plc or 77
microprocessor control unit by connecting the free loop diode to the cause that you are going to damage 78
the semiconductor switching elements. 79
So in here we can see this is just steps . 80
Then it means switching frequency at the pulses that we can think 81
This is direction 0 or 1 in here. 82
We need to get steps from our motor and we need to. 83
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We need to get a switching frequency from the plc or control unit an etc. and we need 85
to get our direction information. 86
These two will go inside control layer after control layer. 87
These informations are going to go switching later than this switching layer is going to run our motor 88
and in here you can see diode and resistor and diode and a Zener diode. 89
Usage for the our stepper motors for to protect our stepper motors. 90
Circuit in here. 91
Okay we are activating transistor and in here we have a coil. 92
Okay. 93
And that moment we need to prevent our stepper motor circuit from reverse induction 94
voltage. 95
And if stepper motors types are not known. 96
This is really another one important point. 97
Connection type must be found first. 98
So if there are four cables coming out from the motor our stepper motor So this indicates that our motor 99
is bipolar. 100
There are four coils in stepper motors one cable is removed from each coil. 101
There are five cables and one of which is common. 102
So there are four cables for the run. 103
Our stepper motor and one cable comes and that cables is our common cable and there is a constant resistance. 104
Really important point is here the constant resistance value between the coomon Cable and the other 105
four cables in our measurement with ohmmeter so if we measure with our multimeter or ohmmeter between 106
the cables one cable must be a constant resistance value with anothers so we can find common cable 107
like this method. 108
The motors operating voltages applied to this cable which cable to the common cable we connect the ends 109
of switching elements such as transistors or FET to the remaining four cables so 110
We will just give pulses our direction and also our pulses switching frequencies to these four cables. 111
If our connection is correct the motor starts rotating if it is wrong the motor doesn't turn and the 112
motor is going to vibrate. 113
In this case we need to change some of the four wires. 114
This process continues until the correct cables are found and the motor turns and there are 16 combinations 115
of four cables and we find the correct cables after a maximum of 16 trials in here you can see unipolar 116
motor and bipolar motor tables and the steps and which steps which cables are + which cables are 117
- the applied voltages and applied for switching frequencies to these cables. 118
In this table you can see for example total step number four one revolution. 119
If we have a 24 step for one revolution so our step angle is 15 multiply this , it will equal to always 120
360 121
So this is one cycle and one turn degree. 122
So in here for example we have one hundred. 123
Step number four one revolution our step angle will be 3.6 124
And if we have four hundred. 125
Step number four one revolution or step angle is going to be zero point nine degrees. 126
And if our stepper motor has six wires it means that the 4 coils available are divided into 127
two groups and the common cable is separated from them so we can say there are two groups as three wire 128
and two coil cable and one common cable. 129
And there is no electrical connection between them. 130
It is quite easy to distinguish between multimeter and this three group. 131
So in these separated groups the cable with the constant resistance with the common cable like four 132
cable and I mean four plus one common cable five wire stepper motors and it's also similar like six 133
wires we need to find a common cable as a result after compared cables resistance common cables can 134
be found easily then it looks like five wire stepper motor the work to be done next is the same as four 135
five wires the motor shaft must never be turned during the measurement of the measuring instrument resistance 136
to be produced at the poles can cause inaccurate measurements for example the wormscrew connected to 137
stepper motor and it moves to table and work piece back and forth during this movement the milling 138
cutter removes sawdust from the workpiece. 139
So in here we will do some calculations the step of the wormscrew is 2 mm and the stepper motor performs 140
one point eight degree steps let's take these values and let's find some detail information so it 141
takes two hundred steps in one turn because one point eight degree multiply by two hundred. 142
So we have one turn so two hundred sixty degree multi divided by one 1.8 a degree we 143
will get two hundred and steps in one turn. 144
The amount of feed per step is to two millimeters here two divided by two hundred step and we will get 145
zero point zero one millimeter per step the motor must perform ten divided by zero point zero 146
one and one thousand steps for one centimeter we found it now as a centimeter . 147
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How motor must performing ? 149
And for one centimeter motor turns. 150
One thousand steps. 151
Four long metal removal. 152
So stepper motor will take one thousand steps and the stop for one centimeter. 153
Whether the part is soft or hard the system should be prompt to move at speed of zero point zero two 154
millimeter per second. 155
In this case zero point zero two divided. 156
Zero point zero one so two degree motor must turn two steps per second. 157
So the switching frequency will be for one cm we get this value 1000 divided by 2 ,500 millisecond. 158
Will be our switching frequency the bench will take 1 cm pet in five hundred seconds. 159
Why. 160
Because 500 milliseconds. 161
Multiply by 1000. 162
This value 163
So this value result to the multiplication result is five hundred seconds. 164
One cm equals 1000 step. 165
Multiply by 500 ms and we got this value at the end of this process. 166
The milling knife will be removed from the piece and the must reach to starting point of the machine. 167
This is really important. 168
1 goes forward. 169
It needs to come backward and to prevent loss of time in return. 170
It may be requested to run at two hundred steps per second we can calculate our stepper motor 171
details and the steps and the switching frequency and the distances we'd like this and we have in here 172
the driving methods of stepper motors. 173
First of all first option stepper motor one phase driving method only one of the motor 174
windings is excited called single phase excitation the stimulation should be 1 0 0 0 0 1 0. 175
Attention this just one windings are one the rest of all is zero. 176
So 1 0 0 0 the next 1 0 1 0 0 0 0 1 0. 177
And like this it is clockwise direction. 178
If we start from the last winding to first winding like this from right to left 0 0 0 1 0 0 1 0 an 179
etc.. the counterclockwise rotation is going to be exist. 180
And with this method we can better understand the working principle of stepper motors and this method 181
is not used much since the torque and stopping characteristics of stepper motors are not good , two 182
Second option driving the stepper motor in two phases. 183
It is called the form extension in which two of the motor windings are simultaneously stimulated in sequence 184
in two fast excitation the transient response of rotor is faster than the single fast excitation. 185
But the power drawn from the power supply has doubled here. 186
So this method is used generally because it's a torque really high and the stopping characteristics 187
are really good for stepper motors in two phases. 188
So third option driving of stepper motors in one and two phases. 189
It's like a half angel rotation method. 190
In this extension mode single phase and two phases are applied consecutively 191
so single phase and two phase are applied together here. 192
The rotor makes a half step really important another point rotor makes a half step move for each excitation 193
signal. 194
Because of this stimulation mode we reduce the step angle of a motor that is 2 degrees from the factory 195
for example to 1 degree. 196
So if we need to run very small degrees and etc. we can run our stepper motors. 197
The third option as third option one and two phase altogether and for this video. 198
I'm finished. 199
See you in the next video.