Motor speed controller circuit

[ljcox]

I don't have a CNC Machine. I'm helping a friend who has a machine with the electronic aspects.

He wants me to design and build a motor speed controller so his Mach 3 software can control the spindle motor speed.

However, before I re-invent the wheel, does anyone have a circuit (schematic) of a suitable PWM controller?

His router is 120 Volt AC, 4 Amp.

Any advice will be appreciated.

Len

[TOTALLYRC]

Originally Posted by ljcox I don't have a CNC Machine. I'm helping a friend who has a machine with the electronic aspects. He wants me to design and build a motor speed controller so his Mach 3 software can control the spindle motor speed. However, before I re-invent the wheel, does anyone have a circuit (schematic) of a suitable PWM controller? His router is 120 Volt AC, 4 Amp. Any advice will be appreciated. Len

http://homanndesigns.com/store/index...products_id=21

For $38 dollars is it worth doing it yourself.

Mike

[arturod]

If you have router, probably our C19 AC Frequency Converter: http://www.cnc4pc.com/Store/osc/prod...roducts_id=155. is the easiest way of doing this.

It will add two relay controlled pugs, the first one can be used to connect the router, and the second one for the dust collector or coolant pump. It will provide speed control that goes between 30% to 100% of the router’s max speed.

Thanks,

Arturo Duncan
http://cnc4pc.com

[Al_The_Man]

Originally Posted by ljcox His router is 120 Volt AC, 4 Amp. Any advice will be appreciated. Len

You haven't said what type of motor it is? Universal, Induction, DC etc?
Al.

[arturod]

Al,

Single phase, brushed AC motors, like common wood routers…..

Arturo Duncan
http://cnc4pc.com

[Al_The_Man]

OK, Universal.
I have never tried them on DC though.
Al.

[arturod]

Al,

It works like the speed controller that comes on routers; it chops the original AC frequency. Like a VFD, but without rectifying it before. It will not work with DC motors.

Arturo Duncan
http://cnc4pc.com

[Al_The_Man]

I do realize, I was referring to using a Universal motor on DC.
Some years back, Motorola came out with an IC to speed control the Universal motors in washing machines, some Treadmill motor manufacturers started using them due the Universal motor being cheaper to make than the PM DC type.
They also adopted this due to the IC having a tach feedback, they just used a simple 10 pulse inductive pick up.
The IC is a TDA1085C, In the treadmill application, the IC controlled a Triac on the AC side of a bridge, the DC output fed the Universal series motor.
They did not use a separate supply for the IC, just resistive dropped the incoming AC.
They worked well.
(The app note on the TDA shows it being controlled with AC, the TM controls used a bridge to feed the motor with DC as mentioned above).
I seemed to remember the brush arcing being less using the DC controller.
Al.

[ljcox]

Originally Posted by TOTALLYRC http://homanndesigns.com/store/index...products_id=21 For $38 dollars is it worth doing it yourself. Mike

Thanks Mike, but his motor is 120 Volt AC. The site you pointed me to appears to be for low voltage DC motors.

Len

[Al_The_Man]

Most of the semi manuf have app notes for Universal motor chopper/phase angle control, Motorola (Freescale).
http://www.freescale.com/webapp/sps/...de=DRMTRUNIMTR
Also Allegro and Maxim are a couple more.
If you are into Micro processors there is the MicroChip site.
Al.

[ljcox]

Originally Posted by Al_The_Man You haven't said what type of motor it is? Universal, Induction, DC etc? Al.

Al,
My friend lives in the US & has limited electronics knowledge.

So I have only seen photos of his router internals. It is a brush type motor and I could not see a a bridge rectifer in the photos.

He has a simple speed controller that he sent me photos of and it is the conventional TRIAC type of controller that uses the motor EMF during the pulse off times as a feedback signal.

It works well at the higher speeds, but is not satisfactory at lower speeds.

Thanks for the response, I'll now read your other posts and those of others.

Len

[ljcox]

Originally Posted by Al_The_Man I do realize, I was referring to using a Universal motor on DC. Some years back, Motorola came out with an IC to speed control the Universal motors in washing machines, some Treadmill motor manufacturers started using them due the Universal motor being cheaper to make than the PM DC type. They also adopted this due to the IC having a tach feedback, they just used a simple 10 pulse inductive pick up. The IC is a TDA1085C, In the treadmill application, the IC controlled a Triac on the AC side of a bridge, the DC output fed the Universal series motor. They did not use a separate supply for the IC, just resistive dropped the incoming AC. They worked well. (The app note on the TDA shows it being controlled with AC, the TM controls used a bridge to feed the motor with DC as mentioned above). I seemed to remember the brush arcing being less using the DC controller. Al.

Thanks Al,
I'll study the spec and report later.

I had thought of using an optical tacho, but it requires a modification to his router. So at this stage, I'm trying to do it without resorting to that solution.

Len