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Unread 06-05-2009, 18:21
Gdeaver Gdeaver is offline
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Re: Sensorless back_emf speed controller

There is a 0.0005 ohm current sense resistor on the h bridge low and ground. On page 2 of the schematic lower left the current sense amplifier is shown. Appears they are filtering it a bit. Currently this is only being used for over current protections. This could be sampled when the H bridge is in the on state of the PWM period. This would give the current draw of the motor and if the motor RPM- current curve is known the the approximate velocity can be found. Is this the focus of the post?