# AC motor issues (AC24/DMOC445)



## TheSGC (Nov 15, 2007)

There are three possibilities, first you could have your motor phases not correctly hooked up. 2nd, your encoder may be loose or 3rd your low battery setting is set too high.


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## njloof (Nov 21, 2011)

Ah, great, thank you; that gives me a checklist to go through


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## njloof (Nov 21, 2011)

Fortunately, the answer was behind door #3: my EE2NoAccelBat setting was at 250V. Hurrah! Thank you.

http://www.youtube.com/watch?v=UxpxBHNxfe8


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## TheSGC (Nov 15, 2007)

That's great, now get the AC24 into a car!


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## Arlo (Dec 27, 2009)

Yeh lets see that thing running.


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## njloof (Nov 21, 2011)

It's on my to-do list!


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## Anil (Apr 11, 2013)

Hi everyone,
I am having some trouble with AC24LS motor and DMOC 445. I am operating DMOC445 using CAN communication with another Vehicle Control Unit. Suddenly the motor (AC24LS) has stopped working properly. I am giving a constant setspeed demand and maximum torque limit set to 50 Nm. The motor should run at the set speed. But, the speed of the motor increases to set speed for a second or two, and then speed decreases automatically. After few seconds same thing repeats. The motor does not run smoothly, and therefore vehicle is not able to run.

Please help me with the problem......

I am attaching a graph recorded in DMOC. The graph shows the variation of set speed, actual speed, set torque, desired torque and some other parameters with respect to time.

Looking forward to a positive reply...


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## otedawg (Apr 23, 2012)

Anvil,
This sounds like the same problem as above to me. Set your EE2NoAccelBat lower and try it. Alternatively, this could be an issue with noise on your canbus signal... Make sure you aren't using the vehicle ground as your canbus ground and you have as short a cable as well as a shielded cable between the controller and what it's hooked up to.

Thanks,
Otedawg


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## Anil (Apr 11, 2013)

Dear Otedawg,

Thanks for your concern. I monitored all the can variables today, and found out that the link through can bus was getting disconnected randomly. I could not solve this problem, however I changed the reconnect time of can bus from 200 to 10. This way the can bus is connected again quite fast whenever it gets disconnected. Now the vehicle is in running condition though not very smooth. 
Also, I am using very small length shielded cable ( 10 inches approx. ) with termination resistance of 120 ohms. I am not able to find out the reason for this erroneous behavior of can communication.
If you have any suggestions, please let me know.

Thank you...


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## otedawg (Apr 23, 2012)

Anil,
I still think there may be a problem with your grounds. I have the same type of issues with my DMOC when connecting over RS232. My guess is that your DMOC doesn't have a large ground cable to the body ground, or you are getting some type of interference. If you have access to an Oscilloscope, take a look at the chassis ground and the canbus ground. I've found that mine is periodically pulsing, coincidental with my torque requests.

Thanks,
Otedawg


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## Anil (Apr 11, 2013)

Otedawg,

The DMOC body and vehicle chassis are connected through a small wire, not a large one. I will make more sound connection between them in order to avoid any disturbances. Also, the can ground is not used. The Vehicle Control Unit and the DMOC are connected only through CAN high and CAN low terminals.
I will check with the ground connections and update you with the results.

Thank you.


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## kennybobby (Aug 10, 2012)

*Still need a reference for CAN*

CAN Hi and Lo are a differential signal pair but they still need a ground signal from which to reference. 

Are you running in torque mode or speed mode, or some combination. 

Looking at your graph it appears that the system is responding to the torque command but there is a phase lag of the speed (Hertz, green) and the real torque (dark blue, calculated from the measured current?) that is causing it to go unstable. 

Once it hits the commanded torque then the speedPI control signal (magenta) starts dropping back down toward zero, but the speed Hertz is just starting to climb and hasn't even crossed over above the CANspeed set point--it is totally out of phase. Then once the speed does reach the set point the torque signal gets turned off to prevent overspeeding. 

It's looks like you have both modes trying to control at the same time and they are fighting each other. Depending upon which mode you are trying to operate will help identify the issue. It could be that there is some filtering of the speed signal that is causing the phase lag.


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