Aerotech BL 10-40, Hardware Manual

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BL Wiring Configurations
3.1. Three-Phase Brushless Motors with Unconnected Phases
Most three phase brushless motors require only three connections between the servo amplifier and the
motor. This is due to the motor phases being internally connected in a Wye or Delta style. This form of con-
nection simplifies wiring, ensuring that the servo amplifier only controls and monitors two phase currents,
since the third phase current is always the sum of the first two phase currents.
However, this simplicity has one drawback. This drawback is phase winding imbalances that can cause
torque ripple and make it difficult to compensate, since the servo amplifier only controls two of the three
phase currents. The BL Series amplifier overcomes this problem by providing the RT (return) connection for
six wire motors, like the Aerotech BLM Series linear motors.
Since the BL Series amplifier independently controls current in each of its three phases, six wire motors can
be connected as shown in Figure 3-1. In this configuration, offset and/or gain adjustments of current made in
one phase do not affect those set in the other two phases.
Figure 3-1: Connection of Six Wire Motors to BL Series Amplifiers
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