18 FXM5 User Guide
www.controltechniques.com Issue Number: 5
Full-control
Figure 4-4 Waveforms resulting from full-control
4.3.2 Recommendations
Half-control
Normally use half-control, since this generally produces a lower amplitude of current
ripple. This results in lower torque ripple in the motor.
Full-control
Full control causes the thyristor bridge to force the field current more rapidly towards
zero at each half cycle. This increases the amplitude of the ripple current, but gives
faster control of the field-current level. Use full-control under the following conditions:
• When very rapid field-weakening is required
• Motors that have an unusually long electrical time-constant
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