ST72141 in generator mode

[wake_up_neo_and]

Posted on January 16, 2004 at 11:45

ST72141 in generator mode

[wake_up_neo_and]

Posted on May 17, 2011 at 10:16

Is it possible to use the st72141- motor- control- peripherie as generator- regulation? We use a motor also as generator and in this mode we try to regulate the velocity. This seems not to be possible.

any ideas? thx S.A.S.U.

[gaetano]

Posted on May 17, 2011 at 10:16

Please, may you give me more details (motor power, field of application, etc.) and in what condition and how you want to regulate this speed?

I'm afraid that the ST7141 is not well suited to do this job (it supposes a nil current to read the BEMF value), but I want to be sure to well understand your system. Regards, Tanio

[gaetano]

Posted on May 17, 2011 at 10:16

Hi Sasu,

when motor is working as generator the current is in that case not controlled by the drive system but forced by the generator. So in that case we have any way to nil the current in a given phase to be able to read the corresponding BEMF, mainly with the ST72141 using the ST BEMF zero crossing principle. The strategy you suggested seems to be the only practicable, even if, in that case, you need to use a external hall sensor. Regards, Tanio

[wake_up_neo_and]

Posted on May 17, 2011 at 10:16

We use the motor to drive a kickboard. The power is not too high. The speed should be set to a fixed value. We have an existing solution where the speed can be regulated in the motor mode. In the motor mode a H-Bridge is used to drive the motor. In the generator mode however there is no regulation done while we recuperate energy into the accumulators. We assume that it is not possible to regulate it in this mode because no zero crossing event ever occurs in this mode. We just are not sure if this is true. Maybe it would be possible if we use a chopper in the recuperation path. I dont have the material with me right no, so i cant give you more details. If you need more please post, i will post the stuff later then.

Thank

[wake_up_neo_and]

Posted on May 17, 2011 at 10:16

I wrote my problem not exactly enough:

I use the motor in both modes (motor, generator). If I am in the generator mode, I would like to measure the velocity. So if I change into the motor- mode I use this stored velocity as reference value to keep the speed constant. This seems not to be possible. A solution could be to switch in the sensor- mode if I am in the generator- mode and to evaluate the hall- sensor signals. I have to check that.. thx S.A.S.U.