What is a Stepper Motor? How Does Stepper Motor work?
The stepper motor is a brushless, permanent magnet pole DC motor that performs an analog rotational motion in response to the pulse strings applied to its inputs. In other words, it is an electro-mechanical device that converts electrical energy into rotational motion. When electrical energy is taken, the rotor and the shaft connected to it begin to rotate in a fixed angular form, step by step. Stepper motors are connected to a drive with very high-speed switching capability. This drive receives input pulses from an encoder, PC or PLC. With each input pulse received, the motor advances one step.
Step motors are referred to by the number of steps in one round. For example, a 325 step engine makes 325 steps in one full turn (360 degrees). In this case, the angle of one step is 360/325 = 1.107 degrees. Permanent magnet poles are located on the moving part. They are not similar to conventional brushed DC motors. The part where the windings where DC voltage is applied is called “stator” and the rotating part is called “rotor”.
When step motors operate in half step mode, their sensitivity increases even more. For example, a step motor with a value of 400 steps/tour makes 800 steps per turn in half step mode. This means a step angle of 0.045 degrees, which is more sensitive than 1.107 degrees. The step motor stator has many poles (usually eight). Their polarity is changed with the help of electronic switches. The magnetism of the rotor is created either by permanent magnets or by external excitation methods. Small teeth are opened on the rotor and stator to achieve better selectivity.
SEE ALSO: What is Alternating (AC) Current?
Usage Areas of Stepper Motors
Although stepper motors have existed for many years, their commercial use has become widespread only in the 1960s when the production of transistors capable of switching high-level direct currents began. With the advances in digital electronics and microprocessor technology since the 1970s, the use of stepper motors has become increasingly attractive and development studies have been carried out on the production and application of these engines worldwide.
Today, stepper motors are used in many control systems in the industry, especially in position control. Most printers (printers, plotters), floppy drivers, hard disk drives (hard disk drivers), card readers, etc. These components have been used in computer peripherals such as and recently in 3D printers. In addition, stepping motors are used as drive elements in numerical control systems, CNC machines, process control systems, robot technology, and many systems belonging to the space industry.
What are the Advantages of Stepper Motors?
• They respond to digital (digital) input signals, so they are ideal elements for microprocessor or computer control.
• In many applications, open loop can be run without the need for feedback.
• They can be operated in a very wide speed range depending on the frequency of the input signs.
• They can be stopped and operated many times without causing any damage. (They can respond perfectly to the desire to stop suddenly while driving or suddenly drive in the opposite direction.)
• They are not damaged without being overloaded, they are quite durable.
• There are no incremental (cumulative) position errors with each new step.
• Since its mechanical structure is simple, they do not require maintenance.
• No greasing and contamination problems.
What are the Disadvantages of Stepper Motors?
• Since the step angles are fixed, the movement from the rotor is pulsed, not continuous.
• Low efficiency when used with conventional drives.
• Step responses are relatively large excess and oscillating.
• Skills are limited in high inertia loads.
• Loads due to friction may generate a position error in open-loop operation even if the error is not cumulative.
• Output power and momentum are limited.
• If it is not well controlled, resonance may occur.
• It may not be possible to operate at very high speeds.