Motor controller system and method for maximizing energy savings

摘要

A motor controller (4) and method for maximizing the energy savings in an AC induction motor (3) at every load wherein the motor is calibrated at two or more load points to establish a control line (6), which is then programmed into a non-volatile memory (30) of the motor controller. A DSP-based closed-loop motor controller observes the motor parameters of the motor such as firing angle/duty cycles (23), voltage (37), current (9) and phase angles to arrive at a minimum voltage necessary to operate the motor at any load along the control line. The motor controller performs closed-loop control to keep the motor running at a computed target control point, such that maximum energy savings are realized by reducing voltage through pulse width modulation.

主权项

1. A system for controlling an AC induction motor to conserve energy, the system comprising:
a processor that communicates with a computer-readable non-volatile memory having instructions stored thereon that, when executed by the processor, cause the processor to: sweep a control space of said AC induction motor; obtain operating parameters of said AC induction motor; establish a control line from said measurements; receive said control line at said motor controller; perform a closed-loop control of said AC induction motor in accordance with said control line to observe an operating parameter; drive the observed operating parameter of said AC induction motor relative to said control line, the observed operating parameter comprising a current; detect zero-crossings of positive and negative halves of a current waveform of said AC induction motor every cycle by:
obtaining a positive voltage as a reference for a positive half cycle;obtaining a negative voltage as a reference for a negative half cycle; andtransmitting signals through an OR gate to create composite current zero-cross digital signals.