| 摘要 |
A voltage control system for an induction motor, consisting of a SCR AC voltage controller with sensing and control circuitry, adjusts the motor voltage in response to the load torque demand, thereby minimizing the motor's magnetizing current and its associated losses. The motor displacement power factor angle, which is responsive to load torque, is sensed by directly sensing the motor voltage, deriving its fundamental or line frequency component, and phase-comparing that component with a similiarly derived fundamental component of the motor current. The resulting displacement power factor signal is amplified, together with a stability augmentation signal, to form a phase delay command signal for the AC controller. The stability augmentation signal, representative of the blocking voltage across the AC controller SCRs, is formed by rectifying the 180 Hz single phase sum of the three motor voltage signals.
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