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TMS320F28379D: Dual axis drive Max Motor Speed

Part Number: TMS320F28379D

Hi    

Reading your post.: https://e2e.ti.com/support/motor-drivers-group/motor-drivers/f/motor-drivers-forum/1271711/mcf8315a-speed-control-issue

Try to understand the max Motor Speed vs Back EMF. 

We have a motor, the back EMF is 12Vrms/KRPM.  and the number of poles is 4.  DClink is 270V.  The max speed would be 12990 RPM.  However, the OEM said, the motor can run to 16000RPM without field weakening. 

Where is the problem for this calcuation? 

DCLINK 270 V
SQRT(3) 1.732050808  
Back EMF (RMS) 12 Vrms/KRPM
Back EMF (RMS) 0.012 Vrms/RPM
Back EMF  (RMS) 360 mV/HZ
Max E Speed 433 HZ
Max Speed RPM 12990 RPM

  • Hi Jushua,  in the formular you posted : 

    BEMF constant is peak or rms value? mV/Hz, My calculation using rms value. 12 Vrms/KRPM is given by OME. if I convert the rms to Peak, the RPM even lower.

  • Yes. You should convert the RMS to peak value for calculating the maximum running speed. The calculation speed is just for running the motor without load, the real maximum speed will be far lower than calculation speed since the output torque will need the output voltage as well.