Motor Control

The electric motor is a device that converts electrical energy into mechanical energy, it uses electricity and magnetic field to produce torque to turn the rotor and hence give mechanical work.

Depending upon the application where the motor is used, the motors are controlled by computerized control systems, like solid-state logic controls, or programmable logic controllers (PLCs) to control and manage their torque, speeds, the work or energy delivered. Motor controllers can have many features of controlling a motor that may include but are not limited to starting, stopping, over-current protection, overload protection, reversing, speed changing, jogging, plugging as well as sequence control. Motor Controllers range from simple to complex and can provide control for one motor or groups of motors.

Motors are broadly classified into two categories; AC Motors and DC Motors, based on the source of electrical energy used.

DC- Motor Types: Series, Shunt/Parallel and Compound based on the way the field coils and armature coil circuits are wired. Other types of DC Motors are the Permanent Magnet (PMDC) Motors and Separately Excited Motors.

AC – Motor Types: AC Induction Motors (also known as Asynchronous motor) and Synchronous Motors. They are further classified by their applications like single phase, three phase, Squirrel Cage Induction, Dual Voltage etc.

There are also other types of Motors like the DC Brushless Motor, Stepper Motor, Reluctance Motor, Hysteresis Motor and Universal Motor.

Here are the popular motor types of motors used commercially used and their applications:

• Brushed DC Motors - Used widely in household appliances and in automobiles, and are easy to control because speed and torque are proportional to the applied voltage / current.
• Brushless DC (BLDC) Motors - Ideal for applications that require high reliability, high efficiency, and high power-to-volume ratio as well as providing large amounts of torque over a vast speed range.
• PM Synchronous Motor - Suitable for most sophisticated applications in the industrial segment. PMSMs are ideal for high-accuracy fixed-speed drives. It also has a high overload capability, highpower density, very high efficiency and high response.
• AC Induction Motor (Asynchronous) - ACIM is the most popular motor used for industrial and consumer applications. As it lacks commutator/brushes it exhibits high reliability, high efficiency at high loads and the ability to connect directly to the AC line.
• Stepper Motor - Stepper motors are versatile, brushless, synchronous motors that are widely used in a variety of applications. They can move in accurate, discrete angular increments (steps) in reaction to electrical input pulses, they are ideal for applications that require controlled, precise movements.
• Servo Motor - Servo motors are small and efficient but critical for use in applications involving precise position control, velocity control and torque control.