April 20, 2010

Dynamic or capacitive braking of electrical machine

Dynamic braking is a process in which kinetic energy of rotor is dissipated in external resistor as heat energy. It is an electrical braking process used in many industrial applications. Dynamic braking allows sudden stop of electrical motor without mechanical wear and tear.

In dynamic braking, stator has no supply at the time of braking. However, rotor is rotating due to inertia. In synchronous motor, rotor has a supply even when stator is disconnected from supply. In permanent magnet synchronous motor, rotor is a permanent magnet. In case of induction motor, rotor is very likely to have a residual magnetism. Therefore, in major types

Electrical braking theory, reason of DC injection

 Electrical braking is needed in many applications and used instead of mechanical braking. The advantage of electrical braking is virtually no wear and tear is experienced.

 Electrical braking may be seen in modern cars, traction motor control, train services, alternators and in automotive industries.

 Here I will discuss the basic principle, I will not elaborate in this post because I believe feeding everything in one pack will result in vomiting. So, for deeper understanding, read my blog time to time. Also, you may search my blog to find the later post. I will post them under the label "electrical braking". also, it is a good idea to subscribe via mail, if you want to get my articles in your inbox.

  We understand if we can dissipate motors' kinetic energy quickly, we can implement a braking. So, all we need is to devise a way to dissipate kinetic energy rapidly.

   The main theory of electrical braking is to use a DC (direct current) injection to provide magneto motive resistance to the running rotor. If a DC flux is provided to the rotor and rotor cuts through it, it eventually slows down because DC injection effectively produces a electrical (or more accurately, magnetic) resistance as described below.