Stepper Motor vs DC Motor
The principle used in motors is one aspect of the principle of induction. The law states that if a charge is moving in a magnetic field, a force acts on the charge in a direction perpendicular to both the velocity of the charge and the magnetic field. The same principle applies for a flow of charge, then it is current and the conductor carrying the current. The direction of this force is given by Fleming’s right hand rule. The simple result of this phenomena is that if a current flows in a conductor in a magnetic field the conductor moves. All the motors are working on this principle.
More about DC motor
DC motor is powered by DC power sources, and two types of DC motors are in use. They are the Brushed DC electric motor and Brushless DC electric motor.
In brushed motors, brushes are used to maintain electrical connectivity with the rotor winding, and internal commutation changes the polarities of the electromagnet to keep the rotational motion sustained. In DC motors, permanent or electromagnets are used as stators. The rotor coils are all connected in series, and each junction is connected to a commutator bar and every coil under the poles contributes to torque production.
In small DC motors, the number of windings is low, and two permanent magnets are used as the stator. When higher torque is needed, the number of windings and the magnet strength is increased.
The second type is brushless motors, which has permanent magnets as the rotor and electromagnets are positioned in the rotor. Brushless DC (BLDC) motor has many advantages over brushed DC motor such as better reliability, longer lifetime (no brush and commutator erosion), more torque per watt (increased efficiency) and more torque per weight, overall reduction of electromagnetic interference (EMI), and reduced noise and elimination of ionizing sparks from the commutator. A high power transistor charge up and drives the electromagnets. These types of motors are commonly used in cooling fans of computers
More about Stepper Motor
A stepper motor (or step motor) is a brushless DC electric motor in which full rotation of the rotor is divided into a number of equal steps. The motor’s position can then be controlled by holding the rotor at one of these steps. Without any feedback sensor (an open-loop controller), it has no feedback as a servo motor.
Stepper motors have multiple protruding electromagnets arranged around a central gear-shaped piece of iron. The electromagnets are energized by an external control circuit, such as a microcontroller. To make the motor shaft turn, first one of the electromagnets is given power, which makes the gear teeth magnetically attracted to the electromagnet’s teeth, and rotates to that position. When the gear’s teeth are aligned to the first electromagnet, the teeth are offset from the next electromagnet by a small angle.
To move the rotor, the next electromagnet is turned on, switching off the others. This process is repeated to give a continuous rotation. Each of those slight rotations is called a “step”. An integer number of multiple steps complete a cycle. Using these steps to turn the motor, the motor can be controlled to take a precise angle. There are four main types of stepper motors; Permanent magnet stepper, Hybrid synchronous stepper, Variable reluctance stepper and Lavet type stepping motor
Stepper motors are used in motion control positioning systems.
DC Motor vs Stepper Motor
• DC motors use DC power sources and are classified into two main classes; brushed and brushless DC motor, whereas Stepper motor is a brushless DC motor with special characteristics.
• A common DC motor (except connected to servo mechanisms) cannot control the position of the rotor, while stepper motor can control, the position of the rotor.
• Steps of the stepper motor have to be controlled with a control device like a microcontroller, while general DC motors do not require such external inputs for operation.