Model magnets and their interaction in Spice ??

May 06, 2014 2 Replies

Could some electronics guru please shed some light on this ? Suppose I wish to analyze magnetic interaction in Spice, e.g., a moving coil ammeter, or a simple brushed DC motor. The field magnets may be modeled as inductors with steady DC current through them, but how would one simulate the commutators that reverse the current through the rotating coil ? Any hints, suggestions would be very valuable. Thanks in advance for your help.


Finite element analysis would seem more suited to the solution of your question than Spice. ...Jim Thompson

| James E.Thompson | mens | | Analog Innovations | et | | Analog/Mixed-Signal ASIC's and Discrete Systems | manus | | San Tan Valley, AZ 85142 Skype: Contacts Only | | | Voice:(480)460-2350 Fax: Available upon request | Brass Rat | | E-mail Icon at http://www.analog-innovations.com | 1962 | I love to cook with wine. Sometimes I even put it in the food.

To expand on what Jim's saying:

There's a whole lot going on in a magnetic machine that SPICE doesn't cover -- inductances change as the geometry changes, voltages get induced in coils as they move through field lines, etc.

You can make some simplifying assumptions about a magnetic machine and SPICE it as if it were a circuit element, but you can't really capture all the behavior with SPICE.

If you don't believe me, go try to model a variable-reluctance motor in SPICE. See how far you get.

Tim Wescott Wescott Design Services http://www.wescottdesign.com

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