Motors are engineering marvels without which the world would come to a standstill. Motors generally provide rotational motion, but in some cases they offer motion along other axis. Examples of the former are ceiling fans and industrial machines, while the latter includes precision positioning equipments such as 3D prototyping devices. Motors are broadly classified as DC (Direct Current) or AC (Alternate current).
A DC motor provides continuous rotational motion when a magnetic field is created between two opposing magnets. It typically consists of a stator and a rotor. As the name suggests, stator is a stationary outer shell while the rotor is the inner component, also called the armature which consists of an electro magnet. The rotor or armature rotates 180 degrees when the magnetic field is created between the opposing magnets due to polarity difference. The next 180 degrees of motion is created by the brushes which change the polarity. The brushes provide polarity change, which in turn allows the motor to rotate continuously. These are called brushed DC motors.
Brushless DC motors on the other hand are reverse engineered; where the rotor is made up of permanent magnets and the stator consists of electro magnets. The polarity change in this motor is achieved through external controller and hence the name brushless motors.
Automobiles such as cars, trucks, earth moving vehicles or heavy duty automobiles require continuous manoeuvring in terms of direction. This is achieved with the help of a steering wheel. There was a time when a steering mechanism was just a simple rack and pinion assembly which required a lot of effort. Today, it has been replaced by steering motor, which is attached to the steering assembly. Due to its high power density achieved due to rare earth magnets, it provides effortless manoeuvring. This motor is activated when the turning radius is large. Once the motor is activated, the task of turning the steering wheel becomes extremely easy.
A step motor is unique in the sense that it uses electrical impulses to generate rotational motion. Each rotation of the motor is divided into number of steps; which can vary but limited to 200, assuming each step is of 1.8 degrees. Each pulse moves the motor by one step. The outer ring or the stator has grooved electro magnets while the inner iron gear (rotor) also has teeth around it. Step motors do not depend on feedback mechanism because the step is controlled by a pulse.
Step motors are maintenance free, provide high torque at low speeds due to direct drive technology and because of minimum transient response, also offer accurate positioning capability.