Abnormal Kt detect with DRV10983

Howard Zou

Other Parts Discussed in Thread: DRV10983

It can be found in the datasheet that "For any given motor, the integrated value of BEMF during half of an electrical cycle is constant. It is determined by motor velocity constant Kt"

Is this the same Kt in the equation BEMF=Kt* speed?

If so, why they are the same?

over 9 years ago

0 Rick Duncan over 9 years ago

TI__Guru** 114905 points

Hi Howard,

Our experts have been notified and should reply soon.

0 Krushal over 9 years ago in reply to Rick Duncan

TI__Expert 3010 points

Hi Howard,

DRV10983 compares programmed Kt with calculated Kt (by integrating each cycle of BEMF) for abnormal Kt lock. The calculated BEMF is dervived from formula (U - IR) and not Kt*speed

Regards,

Krushal

0 Howard Zou over 9 years ago in reply to Krushal

TI__Genius 12365 points

Hi Krushal,

I know that calculated BEMF is derived from formula(U-IR), my question is just why the integration of BEMF each half cycle should be equal to Kt.

Regards,

Howard

0 Krushal over 9 years ago in reply to Howard Zou

TI__Expert 3010 points

Hi Howard,

The integration or area under curve for a*sin(w*f*t) is equal to a/(pi*f) where f is frequency, a is amplitude, w is 2*pi. So basically we are dividing amplitude by frequency to get back emf constant (mV/Hz) by integrating BEMF

Regards,

Krushal

0 Howard Zou over 9 years ago in reply to Krushal

TI__Genius 12365 points

Okay, thank you for your answering.

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Abnormal Kt detect with DRV10983