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Robert Noel Reddington
Grand Master
Username: bob_uk

Post Number: 1143
Registered: 5-2015
Posted on Monday, 03 October, 2016 - 09:15:   Edit PostDelete PostView Post/Check IP

dynamo amplifier.

To control thhe speed of a DC motor poses problems because varying DC voltage is not as simple as it first seems.

one way was to uses resistances but theses get hot and consume power and therefore inefficient esp in traction motor applications.

another is pulse width modulation. if a 100v DC supply is turned on and off fast then if the supply is turned off for 50% of the time then you get 50v. This method works ok.

But when 100 hp plus motors are being used then the power electronics gets too heavy duty and expensive.

So use an amplidyn which is a dynamo driven by what ever. the dynamo drives the traction motor[s]. To regulate the speed of the traction motors the field winding of the dynamo is pulse width modulated.
The dynamo output then follows the field signal and faithfully reproduces the signal but 10,000 fold.

Invented in the first world war to control naval guns, cranes and lifts.
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Patrick Ryan
Grand Master
Username: patrick_r

Post Number: 532
Registered: 4-2016
Posted on Monday, 03 October, 2016 - 17:51:   Edit PostDelete PostView Post/Check IP

Very interesting read Robert.
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Robert Noel Reddington
Grand Master
Username: bob_uk

Post Number: 1145
Registered: 5-2015
Posted on Tuesday, 04 October, 2016 - 05:45:   Edit PostDelete PostView Post/Check IP

Your interest in hybrid truck stuff, makes this interesting for you , wikipedia.

more traction motor stuff
volts = rpm
amp = torque

volts x amps = horse power = watts

torque x rpm = horse power = watts.

Isn't the above neat