| 摘要 |
A control system for energizing a direct current (DC) motor with alternating current (AC) power includes a first voltage sensor for a peak voltage of AC power; a second voltage sensor for a counter electromotive force (EMF) of the motor; a current sensor for an armature current of the motor; a digital processor having a first current controller responding to sensed armature current and a current reference, a cooperating second current controller responding to sensed peak voltage, sensed counter EMF and the current reference signal, and a gating circuit responding to the controllers; and a thyristor converter circuit sequentially gating portions of half cycles of AC power to the motor in response to firing signals from the gating circuit. The controllers may control a gate angle of the firing signals, the control system may include a third voltage sensor for a terminal voltage of the motor, and the armature current may have discontinuous and continuous waveforms. The processor may calculate a start of continuous current value which is a function of a calculated peak voltage of the AC power and a calculated counter EMF of the motor. The calculated counter EMF is sensed when an absolute value of sensed armature current is less than the start of continuous current value but, otherwise, the calculated counter EMF is related to motor terminal voltage. The calculated peak voltage of AC power is an average of an absolute value of a peak positive sensed voltage and an absolute value of a peak negative voltage under calculated discontinuous current conditions but, otherwise, the calculated peak voltage is the average plus a calculated commutation notch line voltage loss. The calculated commutation notch line voltage loss may be a function of the gate angle, the sensed armature current and the calculated peak voltage. The gate angle may be a sum of gate angles from the two controllers.
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