| 摘要 |
A closed-loop induction motor power control employs a novel digital phase-locked loop which maintains a constant torque over all contemplated motor speeds. Digital processing means incorporating a novel digital phase detector employing an exclusive OR function provides a correction signal to a voltage controlled oscillator controlling the speed of the induction motor. The correction signal provided thereby is proportional to the difference between the desired slip frequency and measured slip frequency. The closed loop control system is capable of generating a constant slip frequency, either positive or negative, with respect to the rotor speed. The system is also capable of automatic shutdown and rapid response to variable-inertia loads thereby minimizing the possibility of excessive power converter current which could result in an overload shutdown as may occur during motor start up, rapid motor acceleration, or rapid increase in inertial loading.
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