The stepper motor is a type of brushless synchronous electric motor. Let’s have a look together!
The stepper motor is powered by direct electricity and keeps the rotor stationary in a certain position.
If you want to rotate the rotor shaft a few degrees precisely, you can do it by sending a well-defined sequence of pulses. A certain number of “steps” are used to make a complete revolution of the engine and the amplitude of a step is expressed in degrees.
The stepper motor consists of two equal half-stators but 90° out of phase. On each of these half-stators there are two coils, or phases, connected to a central socket.
These phases are arranged in a circular manner on the stator and operate like electromagnets. Each coil is always crossed by electrical current in the same direction. By providing a certain pair of phases, we obtain two magnetic fields which force the rotor to position itself in a certain position. By switching the power supply to the other phase of one of the two semistators, the polarity of its magnetic field is inverted, and the rotor jerks towards the new position.
So when electricity passes through one of the coils, it becomes magnetic and this moves the motor shaft in its direction.
The stepper motor has a high torque and can work at very low speeds without the need for gearboxes. It is also possible to manage the stepper motor with a digital circuit (think of a microcontroller or a PC) without using devices capable of detecting its angular position.
Three main strengths:
- extraordinary stopping accuracy;
- ideal for low and medium speed operation;
- good adaptability.
You can use the stepper motors for low powers and modest speeds applications. The main application of these stepper motors concerns, for example, in the positioning of processors for the inspection of images sensitive to vibrations, cam drives and other mechanical devices that servomotors have difficulty controlling.
Festo offers an integrated solution: stepper motor with position controller. This offer is suitable for the modular mechatronic multi-axis system with moving loads up to 20 kg. The servocontrol functionality of these motors allows many advantages, such as long life, the availability of a closed loop system through an optional encoder or an open loop system without encoder, convenient in price and in greater reliability due to the lower risk of instability.
FEATURES OF THE FESTO STEPPER MOTOR
- Double-phase hybrid stepper motor with high torque and a high protection class
- Optimised cable sets, suitable for use with energy chains and UL certified
- Plug system suitable for industrial use
- Size 28, 42, 57, 87
- Holding torque 0.09 … 8.6 Nm
- Voltage 24 … 72 V DC
- Nominal current 1.4 … 9.5 A
FEATURES OF THE STEPPER MOTOR CONTROLLER
- Analog interface ± 10V DC as target RPM value
- Operation: closed-loop system or attractively priced open-loop system as a standard stepper with stepper motor and no encoder
- Automatic motor current reduction
- Active stepper angle monitoring and resonance suppression
The stepper motor therefore has a close relationship between the number of pulses sent to the different phases and the angular displacement of the motor. The average speed of rotation is directly proportional to the frequency with which the current pulses are sent.