Electrical Machines and Magnetic Fields

This course covers the comprehensive study of electrical machines, focusing on Direct Current (DC) and Alternating Current (AC) machines. It begins with an exploration of magnetic circuits, their single and multiple excitations, and their application in the design and operation of electrical machines. For instance, the course explains how a DC machine operates, the role of brushes and commutators, and how to avoid them by swapping the stator to the rotor side and vice versa.

The course further delves into the concept of magnetic fields in electrical machines, discussing the types of magnetic fields present in DC and AC machines, the concept of rotating magnetic fields, and their importance. It also explains the role of field winding at the stator side in a DC machine and how the magnetic fields are constant.

The course also covers the symmetrical and unsymmetrical displacement of mechanical and electrical aspects in relation to two coils. It explains how the excitation of the coils affects the magnetic field vectors and the resultant flux vector. For example, the course uses the example of two coils, AA dash and BB dash, mechanically displaced by 90 degrees and electrically excited with a 90-degree phase shift, to illustrate the formation of symmetrical rotating magnetic fields.

Finally, the course concludes with a discussion on the impact of changing displacements on unsymmetrical rotating magnetic fields, which can cause vibrations, noise, torque pulsations, and increased stress on conductors. It emphasizes the need for symmetrical mechanical and electrical displacement for optimal machine operation.