No answers, but a question for you.  Where might be the best place to get my
hands on a synchronous AC motor ?  The spec's you are stating are pretty
much exactly what I am after.  This motor is to drive a syncronous spark gap
for a 1.8kW tesla coil generator.

If you find more info on controlling these motors, esp. via a micro, I would
be very interested.

Rgs
Ian.

-----Original Message-----
From: pic microcontroller discussion list
[mailto:PICLIST@MITVMA.MIT.EDU]On Behalf Of Simon Davies
Sent: Tuesday, 14 October 2003 9:01 pm
To: PICLIST@MITVMA.MIT.EDU
Subject: [EE]:Speed control of Synchronous motors


Hi Everyone,

I have a small home project that involves speed controlling a 650W 220V ac
synchronous motor that runs at 1450rpm.

The motor drives a lathe and it would be really useful if I could adjust the
speed of the motor such that:
a) I am not constantly changing the drive belts
b) the speed can be slowed down considerably for more delicate operations
such as cutting threads etc.

I know that controllers and motors are available but they are 'serious'
prices and seem to be intended for industrial use and appear to be 'DC'
types - i.e. sliprings and brushes.

I had thought about taking the 220vac, rectifying it and then feeding it
through a chopper circuit with a frequency varying between say 35Hz and 85Hz
controlled by a panel switch.

So the questions:
Has anyone any experience/circuits/suggestions about this form of speed
control?
Any comments or suggestions about my proposed methods - especially with
respect to the capacitor start mechanisms that are fitted.

Thanks in advance for your help.

Regards,

Simon



Simon Davies

Senior Business Consultant

------------------------------------------------------------------------

Infitel International N.V.

Meentwal 13, 3430 AC Nieuwegein, The Netherlands

------------------------------------------------------------------------

+31 (0) 30 6025 029 (NL)

+31 (0) 30 6 025025 (Fax

E-mail: Simon.Davies@infitel.com

http://www.infitel.com



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