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AC motor connected to Raspberry Pi

Posted: Fri Dec 27, 2013 5:27 am
by schitale
Hi,

I am working on Raspberry Pi - B. I have to connect it to a AC Servo Motor Yaskawa 10C3C11.
I will have the following connections:

Rasp Pi ---- DC to DC booster ( 5 volts to 12 volts) ------ DC to AC inverter (12 volts DC to 110 Volts AC) ---- AC Servo motor.

I have to order the Booster and Inverter, what speifications would be important?

http://www.galco.com/buy/Yaskawa/sgmcs-10c3c11 (Motor Specifications)

PS: I am sending PWM control signal from Pi to Motor

Re: AC motor connected to Raspberry Pi

Posted: Fri Dec 27, 2013 9:06 am
by Ravenous
Wow that is a serious motor. Looks like they expect you to use the special servopack in the selection guide document... do you have any experience driving high voltage things like that? You'd at least need to know something about the coil resistance and inductance.

Out of interest, do you have a quote for the price of something like that? :shock:

Re: AC motor connected to Raspberry Pi

Posted: Fri Dec 27, 2013 11:27 am
by FLYFISH TECHNOLOGIES
Hi,
schitale wrote:Rasp Pi ---- DC to DC booster ( 5 volts to 12 volts) ------ DC to AC inverter (12 volts DC to 110 Volts AC) ---- AC Servo motor...
PS: I am sending PWM control signal from Pi to Motor
Does the DC/DC booster have "enable" input ?

Since the motor is 200W, I have strong doubts that booster + inverter is the way to go...


Best wishes, Ivan Zilic.

Re: AC motor connected to Raspberry Pi

Posted: Fri Dec 27, 2013 11:33 am
by Burngate
200W motor, so the 12v into the inverter is going to be >17A, and the booster will need >40A @ 5v

Since the Pi can't supply that, I'm of the opinion that I don't understand what you're trying to do.

Re: AC motor connected to Raspberry Pi

Posted: Fri Dec 27, 2013 3:10 pm
by Tage
The motor current can be up to 7Arms which translates into 1400W. it is better to use a motor drive that is powered from the mains voltage than to try to boost the voltage from 12Vdc to a high ac voltage that can be fed to the motor drive (inverter). you could purchase a true sinewave inverter that runs from 12V battery, if you absolutely have no way of using mains voltage. (Prosine 1000 is one example). I am not sure if the motor drive can run from a cheap quasi square wave output inverter (then call them "modified sinewave" which is misleading). in any case, using a 12V to 110V converter is very inefficient.

there appears to be a control unit Yaskawa Servopack SGDV 2R1 F E1 ... etc, that is designed for this motor and is powered from single phase 100Vac/115Vac.

Re: AC motor connected to Raspberry Pi

Posted: Sat Dec 28, 2013 6:25 am
by schitale
Hi guys,

I am working on a Spasticity Detection Robot. My main objective is to control the SGMCS 10C3C11 using the Raspberry P-B board. I had an existing model of the robot which has the SGMCS motor + SGDV servo drive (controller).
But, the need for incorporating Raspberry Pi was that, SGDV servo drive was used by a software called SIgmawin.
But, Sigmawin did not give us enough flexibility in the control of the motor. It has some predefined inputs (eg: Forward direction x angle y speed , Reverse Direction k angle j speed).
I was able to control a small DC Servomotor with 3 Volts input.
So, using the same principle I want to control the bigger motor. So, I thought of using the DC-DC Boost and Inverter.

Do let me know, what is the right approach to get this.

Thanks

Re: AC motor connected to Raspberry Pi

Posted: Sat Dec 28, 2013 9:26 am
by jasonclark
Hi,
I used to be in the motion control industry and my employer used to sell Yaskawa drives+motors.

You will need the correct servo drive for this. It'll take single phase power and manage everything for you.

The drives can run in a few different modes- Torque control (you provide +/-10V as a torque control), Speed Control (you provide +/-10V as speed control) and possibly a position control..

It may be possible to communicate with the drive over ModBUS and so the command would be digital from the RaspPi. You can use a Line Driver to give yourself RS485 signal levels from the RasPi UART.

This would be my preference as the Servo Drive can then take care of the realtime operations, leaving the Pi for other things.
Yaskawa drives are very good, and also have a pretty good AutoTune feature, so set-up can be fairly easy.

I doubt you'll get much from the Motor without the correct Servo Drive.
It's possible to DIY, but I would expect this to be difficult to do well, RasPi & Linux is not "real-time" and really not suited to this task. With the high voltage electronics and complicated AC signals, you would be better getting a simple AC motor with an inverter drive, or using the correct Servo Drive.