Simulating Electronic (Analog) Motor Speed Control

[Diodemoe]

Is there a way of simulating (Analog) Electronic Speed Control in Multisim 10?  The system involves a permanent magnet DC motor with quadrature encoder, a frequency-to-voltage converter, operational amplifier circuits, and a MOSFET driver.  The parts that I am wondering about are the motor and encoder.

[lacy]

Multisim has a motor but I don't see a quadrature encoder. The only problem I see is with the quadrature encoder as it partially works in  the mechanical area on a rotating shaft. There are no moving parts in Multisim or any other spice software that I know of. That would have to be simulated by creating a circuit in the electrical area that would mimic the mechanical function of the quadrature encoder. This could be a huge task and I wouldn't even begin to know how to accomplish that.

Multisim's motor has a pin on it that electrically represents the RPM as a voltage that is read on a multimeter. I have found that it doesn't always work as expected in all applications. You would just have to try it and see it it works for you by adjusting it to your motor specifications.

This is all I can tell you and if someone has an idea I would hope they would post it for you

[lacy]

I need to make a correction to my last message. Multisim does have a few "moving parts". It has relays and switches that you can acutally see changing from open to closed and light bulbs that light as well as LEDs that show light . I have not seen any rotating parts that you can place a target on and  break a light beam with it like a motor shaft. Nor does it have rotating parts to where you could tie in a magnetic speed sensor. I thought I would correct this as I really don't consider these parts I metioned above as true mechanical components. I apologize if my way of thinking about these components has caused a problem.

[Diodemoe]

Thanks for your help Lacy!  I understand perfectly what you mean.  I suspected as much.  The only way might be, as you suggest, to build mathematical models for the missing electomechanical components (though one could build on top of the motor model you mentioned).  Do you know if one can encode these mathematical relationships in equation form (like in Simulink, for instance) without having to build a circuit to represent them?

[lacy]

I do not have a real answer for your last question. It may be possible, but I just don't have any information as to how it can be done. Maybe the NI team can read this post and answer the last question as they probably have better information on that than I do about how to enter mathmatical expression into Multsim. I do know that Multisim will allow mathmatical expressions in cetain instances, but I do not know how or where you might be able to enter that information. They may even know of a way of doing what you need with one of the source signals or maybe even a database component that could mimic the behaviour you need. I just don't know that information or I would definitely tell it  to you.

Sorry that I haven't been much help here, but I can only do what my knowledge allows me to do.