Motor Stepper Theory
Stepper motor is the electric motor is controlled with a digital free-free, not to provide a voltage continuously. Cartenarian balance shaft is translated into rounds, where each round requires a specified number of credits. One free round result in one step increase, which is part of a full lap. therefore, the calculation of the amount of credits can be applied to obtain the desired number of rounds. Calculation of credit automatically show amount of rounds have been done, without requiring the information back (feedback).
The accuracy of the stepper motor control movement primarily influenced by the number of rounds each step; the more the number of step, the more precise the resulting movement. For higher accuracy, several stepper motor drivers to share a half-step normal step (half step) or micro-step.
Part of the stepper motor that is arranged on the rotor, stator, bearing, casing and the wick. Axis is the specialty of the rotor axis which is the center of the rotor, so that when the rotor rotates rotary axis participate.Stator has two parts, namely the core and coil plate. From the core plate stepper motor usually ignites with the casing. Stepper motor casing made of aluminum and this functions as a bearing holder and the stator is handle of four baud. In the motor stepper has two bearing fruit that is bearing the top and the bottom bearing.
In the stepper motor is generally a written specification of Np (= credits / rotation). While the speed of credit expressed as pps (= credit per second) and speed of play is generally written as ω (= rotation / min or rpm). Turn the stepper motor speed (rpm) to expression can use the free speed (pps). Because 1 rotation = 360 degrees.
Basically the stepper motor are grouped into 3 types, namely:
a. Permanent Magnet (PM)
Appropriate name, version formed PM stepper motor has a rotor permanent magnets. Usually have low speed, the tool with torque low angle and large steps, can be 45 or 90 degrees.
b. Variable Reluctance (VR)
Stepper motor of this type of rotor has a unique shape that is cylindrical and the unit has all the serration has a relationship with the pole-pole stator.Magnet on the rotor does not use this type of permanent magnet. Stator twist by winding so that at the time flow, will result in stator magnet poles. Number of serration on the rotor will determine the steps, or step motor. Differences version formed PM stepper motor with the motor version formed VR VR torque have a relatively smaller compared with the stepper motor version formed PM. Another thing that you can view the remaining magnetic is very small so that when the stepper motor does not flow then when torque have not played against that. Step angle stepper motor version formed VR that varies up to about 30o. Version formed VR stepper motor has a small torque.Often found in the printer and instruments factory that light that does not require a large torque.
As in the picture above, the motor has 3 pairs of stator poles (A, B, C) a separate set of 15 degrees. Cash flowed to the pole through a motor winding that causes the magnetic tug parallel rotor teeth to pole A. If we give the energy to pole B will cause the rotor rotates 15 degrees parallel polar B. This process will continue to pole C and A to pole back with counter-clockwise direction.
c. Permanent Magnet - Hybrid (PM-H)
Hybrid permanent magnet stepper motor was a refinement in which the stepper motor has a speed 1000 step/sec but also has torque large enough can be said that the PM-H stepper motor is a combination of PM and VR stepper motor. Motor hybrid combines the best characteristics of the motor and variable reluktantion permanent magnet motor. Motor is built with the stator pole teeth and many-rotor permanent magnet. Motor has 200 standard hybrid rotor teeth and rotate at 1.8 degree step angle. Due to the dynamic and high torque and rotates with the speed of the motor this high using on the application that is very knowledgeable.
View from the stepper motor twisted divided into 2 types, namely:
a. Stepper Motor Unipolar
Stepper motor consists of two unipolar winding that has a center tap. Center tap of each coil is in the form of a separate cable that is also connected to center tap so that there is only one cable exit. For the stepper motor in the center tap each - each twist input have cable 6 cable.However, if the center tap already connected in the cable input only 5 cable. Center tap of the stepper motor can be connected to grounding or that there are also connecting it to VCC + this is influenced by the driver used.
b. Bipolar Stepper Motor
Bipolar stepper motor has two types of winding differential is that in the unipolar type bipolar twister a does not have a center tap. Benefits of the bipolar type have torque greater if compared with the unipolar type size for the same. In the stepper motor type is the cable only has four entries. However for movement type stepper motor is more complex compared to the stepper motor movement type unipolar.
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