What are the features of bipolar operation?
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Bipolar operation provides the possibility of connecting the two winding halves of the A and B phases in series or parallel.
Serial connection (the winding resistance and counter EMF are doubled, the winding inductance is quadrupled because both coils are magnetically coupled via the stator core = (2*EMF-2RW-4L)) is used when no high motor speeds (up to approx. 1000 rpm) are required and the power drive or the power supply can only control or deliver a certain current. The nominal current phase of the serial connection must be reduced to the value = current/winding * 0.7.
Parallel connection (the winding resistance is halved and the counter EMF remains constant. The winding inductance also remains constant due to the magnetic coupling = (EMF-1/2RW-L)) enables the highest speeds. The nominal current phase must be increased to the value = current/winding * 1.4. In consideration of the possible speeds, the parallel connection offers the highest achievable power output.
