Ted tedwilliams@nospam :

Every motor becomes a generator when the motor is turned faster than the
rated speed at the rated EMF. This is commonly known as regeneration.

The point is that ST motors are designed to be efficent generators when used
in that mode, and that the circuits that are to be included are design to use
those motors as a source of power when the motor goes into generator mode.

Secondly, if the motor is running in extended range (not possible with
permanent magnet motors) you increase the motor speed by holding armature
volts constant and decreasing the motor field flux. This is known as the
constant Hp mode of operation since as speed increase, the resultant torque
decrease proportionatly thus constant Hp.

Yes, but ST's circuits that they use take gotcha's like this into account, no
matter what speed the motors are used at as generator and not matter what the
voltage/ampage output of the motor/generator the invertor in designed to
convert it to the best range for recharging the batteries.

The motors are not directly connected to the batteries which could result in
the type of problem you relate above. Rather a very intelligent speed
controller with feedback from the motors. If the motors are spinning too
slow indicating that the boat moving slowly the power to the motors are
ramped up. If the motors are spinning too fast thus indicating the boat is
also moving faster than the set speed the motors are used as generators the
resulting power is *conditioned* to the best values to recharge the batteries.

Earl Colby Pottinger

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