A stepping motor or a step motor or a stepper motor is referred to as a brushless DC electric motor that partitions a full pivot into various equivalent steps. The position of the motor can be made to hold and move at one of these steps without any rotary encoder for feedback.

Basics of operation

There is a continuous rotation of brushed DC motors whenever a DC voltage is given across their terminals. The stepper motor is popular by its functionality of changing input pulses (square wave pulses) into an accurately characterized augmentation in the pole position. Each pulse makes the shaft to move by a fixed angle.

Stepper motors come with multiple "toothed" electromagnets that are placed around a central gear formed in the shape of an iron. The electromagnets are made to energize by a microcontroller as well as an external driver circuit. To carry out the turning motion in the motor shaft, firstly, power is supplied to the electromagnet which attracts the teeth gear magnetically. When the teeth gear lines up with the first electromagnet, they are somewhat balanced from the succeeding electromagnet. Now as the following electromagnet is switched ON and the previous one is switched OFF, the gear turns marginally to line up with the following one. This process is then repeated and each of these rotation is known as "step".

The electromagnets’ circular arrangement is split into groups, each group is known as a phase, and every group comes with an equal number of electromagnets. The number of groups is selected by the creator of that particular stepper motor. Each group's electromagnet is interleaved with other group's electromagnets to establish a uniform pattern of arrangement. Let’s understand it with an example. Assume that the stepper motor consists of 2 groups A and B. Along with that it has 10 electromagnets. The grouping will be like ABABABABAB.

Electromagnets that are within a particular group are all energized together. As a consequence, the stepper motor with more phases regularly has more wires to operate the motor.

Advantages

• Low speed and high torque at startup.
• Ease for control accomplished.
• Construction is simple.
• Ruggedness
• It can be operated in an open-loop control system.
• Low maintenance.
• Will surely wok in any kind of environment.
• Less chance to slip or stall.
• It can be utilized in robotics.
• The input pulse is proportionate to the rotational angle.
• Highly reliable.
• Full torque at standstill.
• It provides a quite good response to reversing / stopping / starting.
• As there are no contact brushes in the motor, they are very much reliable. Thus the motor’s life is dependent completely on bearing’s life.

Applications

Stepper motors are commonly used in flatbed scanners, compact disc drives, computer printers, slot machines, image scanner, intelligent lighting, CNC machines, camera lens as well as in 3D printers.

Hope you liked the article on stepper motors. Brands that manufacture them are Applied Motion, CUI and Pololu. Make sure to follow the links as provided.

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Motor drives refer to those circuits that help in running a motor. It can be said in other words that they help in motor interfacing. The motor can be easily interfaced with the drives. Their selection totally depends upon the kind of motor being utilized as well as their ratings (like the voltage, current, etc.). 

Let’s take a reference of a DC motor and understand its major components.

The major components of motor drive present in DC motors are a Motor Driver IC, a controller, Power Supply Unit, DC motor and required connections to the motor.

• Controller – The controller can be a microcontroller or a microprocessor.
• Motor Driver IC – Motor Driver IC (or Motor Driver Circuits) are current amplifiers which convert low current signal taking from the controller to high current signals.
• Motor – Motor is referred to as a mechanic or electric device that can cause motion. Some motors like a stepper motor, brushless DC motor, and normal DC motor might need a driver circuit or a driver IC while interfacing with the controller. DC motor is referred to as that kind of motor that helps in converting DC into Mechanical power. The brushless DC motor consists of an inverter that produces an AC signal to drive the motor and a DC power source. Stepper motor is referred to as a brushless DC electric motor that helps in converting electrical pulses into discrete mechanical motions.
• Power Supply Unit – Offers the needed power to the motor drive.

DC Motor Driver Circuits

Motor Driver circuits are basically current amplifiers. These motor drivers behave like a bridge between the motor and the controller. Motor drivers are produced using discrete parts which are coordinated inside an IC. The motor driver circuit or a motor driver IC takes in a low current signal as an input. The main functionality of the IC is to convert this Low Current signal to a High Current signal which is then provided to the motor. The motor can be a brushed DC motor, brushless DC motor, stepper motor or other DC motors, etc.

Characteristics:

• Better performance
• Supports with the high current drive
• Gives a high level of functionality
• Offers High voltage
• It comes with an assurance scheme to avert the disappointment of motors because of any issues.

What is the need for Motor Driver Circuits (ICs)

While interfacing the motor with the controller, one of the basic needs for the controller's operation is a small amount of current with a low voltage. But the motor needs a high current and voltage for its own operation. Thus we can say that the output generated from the processor or controller is not much to drive a motor. In this case, direct interfacing of controllers to the motor is beyond the realm of imagination and we use a Motor Driver IC.

This was all we have regarding Motor Drives. Hope you liked it. Brands that manufacture them are Schneider, Omron, and Applied Motion. Make sure to follow them using the links as provided.

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