IGBT and MOSFET

[alanmcm]

Anyone able to tell me how these control the speed of a DC motor?

Are they a faster way of switching thyristors? Do they store certain amounts of voltage and only allow through what you want it to?

Been at this question for the last couple of days now and cant seem to find an explanation on the internet of how it actually performs, or maybe I am but im not realizing it. Or if you can point me in the direction of a book that would be great.

Thanks in advance

 

[pennychew]

The first one sounds like a Simon Cowell 'talent' show! I remember something about car audio amplifiers having mosfet in the name so not sure if its something to do with amplification of could be a filter like you say.

Probably not much help!

 

[Marvo]

With a DC motor, depending exactly what type of DC motor it is the speed is controlled by varying the voltage of the supply.

IGBT's or FET's switch the supply to a motor on and off at a set frequency, the rotational speed of an AC motor is relative to the supply frequency so changing the switching frequency of the IGBT or FET alters the motor speed. Both IGBT's and FET's are just very fast, high power semiconductor switching devices, they don't really store energy or 'voltage' as you mentioned, they're essentially just a switch which is either on or off.

Are you studying motor speed control or are you studying the operation and construction of motor drives?

You could look here for some info general speed control http://www.orientalmotor.com/technology/articles/article166-1e.html

Here's some info on DC motor speed control http://nptel.ac.in/courses/108105053/pdf/L-39(TB)(ET) ((EE)NPTEL).pdf

Here's some on brushless DC motors http://www.edn.com/design/sensors/4407580/Brushless-DC-Motors-Part-II--Control-Principles

 

[alanmcm]

thanks thats great and very detailed. Im studying motor speed control and the different ways to achieve it, and also the construction of motor drives. Im studying my HNC in electrical and electronic engineering so have a lot more to learn.