Salient Features of Electro-Mechanical Energy Conversion

An electro mechanical energy conversion involves the process of conversion of electrical energy to mechanical energy or mechanical energy to electrical energy. Commonly, rotary systems such as motors and generators are used for this type of energy conversion. The conversion of mechanical input into electrical output is called as generation and the conversion of electrical input into mechanical output is called
as motoring.

Parts of electromechanical energy conversion devices

An electrical machine showing its inner rotor and outer stator.

Electrical machines are used for almost all electro-mechanical energy conversion systems. An electrical machine has a stator and rotor which contain the magnetic poles and an air-gap between the two. The three parts forms a series path for the magnetic circuit.

Various types of magnetic effects used in electrical machines

Magnetic effect by Permanent magnets: Permanent magnets are used on one side either on stator or on rotor, and coils were used on the other side.

Electromagnetic effect: In electromagnetic effect the magnetic field is generated by current passing through coils called windings. These coils are either wound on stator or on rotor.

Reluctance variation: In these machines the rotor is shaped in such a way that it has a particular pattern of reluctance variation. This rotors always aligns to low reluctance angular position. The magnetic field is applied in the stator in such a way that it follows the same pattern as to rotate the rotor.

• Since the air-gap has maximum reluctance the maximum amount of energy is stored in the air-gap. To produce continuous torque and to move the rotor, the energy stored must be a function of the rotor position. The rotor will always tend to move towards the angular position of the maximum energy stored.
• The ideal output of a motor must be a constant unidirectional torque for a given current.
• An electrical machine can work either as a generator with mechanical input and electrical output or as motor with electrical input and mechanical output, provided certain conditions are satisfied for the corresponding mode of operation.

Also Read:

Electrical Generator
Electrical Transformer