Quote:
Originally Posted by Al Skierkiewicz
Chris,
Again I ask you to consider that the diodes only conduct IF the EMF exceeds the battery voltage which is rare or when the inductive kick attempts to raise the voltage.
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I felt this is what was bothering you Al... and this point needs to be debated.
I don't see the battery voltage entering into it unless all FET's are OFF the return path is through a high side diode and a low side diode on the other side of the bridge. This return path is then through the 12 volt source and ground. But, the JAG leaves a lower FET in the ON state. This shorts one side of the motor to ground and only the diode on the remaining low side of the motor can complete the path to ground. This path is easily completed by reversing the voltage across the inductor.
V_L = -v_diode - i*R - Vemf . This inductor voltage remains until the current drops to zero and we reach the open loop state.