Motor controller system and method for maximizing energy savings

Abstract

A motor controller and method for maximizing the energy savings in an AC induction motor at every load wherein the motor is calibrated at two or more load points to establish a control line, 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, voltage, current 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.

Having thus described my invention, I claim: 
     
         1 . A system for controlling an AC induction motor to maximize energy savings compromising:
 a means for connecting a motor controller to an AC induction motor;   a means for placing a load on said AC induction motor;   a means for removing a load from said AC induction motor;   a means for sweeping a control space of the AC induction motor and taking measurements of operating parameters of the AC induction motor;   a means for establishing a control line from said measurements;   a means for storing said control line in said motor controller;   a means for controlling said operating parameters; and   a means for performing closed-loop control of said AC induction motor to keep the motor running in accordance with said control line.   
     
     
         2 . The system of  claim 1  further comprising:
 a means for placing said AC induction motor in a fully loaded configuration. 
 
     
     
         3 . The of  claim 1  further comprising:
 a means for placing said AC induction motor in a fully unloaded configuration. 
 
     
     
         4 . The system of  claim 1  further comprising:
 measuring a current of said AC induction motor. 
 
     
     
         5 . The system of  claim 4  wherein:
 the current measurement of the AC induction motor is accomplished by a digital signal processor. 
 
     
     
         6 . The system of  claim 1  further comprising:
 measuring phase angles of the AC induction motor. 
 
     
     
         7 . The system of  claim 6  wherein:
 the phase angles measurements of the AC induction motor are accomplished by a digital signal processor. 
 
     
     
         8 . The system of  claim 1  further comprising:
 a means for controlling a firing angle/duty cycle of said AC induction motor. 
 
     
     
         9 . The system of  claim 8  wherein:
 said means for controlling said firing angle/duty cycle of said AC induction motor is accomplished by a digital signal processor. 
 
     
     
         10 . The system of  claim 1  wherein:
 said means for sweeping the control space of the AC induction motor and observing and measuring said operating parameters is accomplished by varying root square means motor voltage of the AC induction motor. 
 
     
     
         11 . The system of  claim 10  wherein:
 said means for varying the root square means motor voltage of the AC induction motor is a digital signal processor. 
 
     
     
         12 . The system of  claim 1  wherein:
 said means for establishing a control line from said measurements is accomplished by a digital signal processor. 
 
     
     
         13 . The system of  claim 1  wherein:
 said means for storing said control line in said motor controller is a non-volatile memory. 
 
     
     
         14 . The system of  claim 1  wherein:
 said means for performing closed-loop control of said AC induction motor to keep the motor running in accordance with said control line is a digital signal processor. 
 
     
     
         15 . The system of  claim 1  wherein:
 said means for performing closed-loop control of said AC induction motor to keep the motor running in accordance with said control line is pulse width modulation. 
 
     
     
         16 . The system of  claim 15  wherein:
 said pulse width modulation is performed using at least one TRIAC driver. 
 
     
     
         17 . The system of  claim 15  wherein:
 said pulse width modulation is performed using at least one SCR driver. 
 
     
     
         18 . The system of  claim 15  wherein:
 said pulse width modulation is performed using at least one IGBT driver. 
 
     
     
         19 . The system of  claim 15  wherein:
 said pulse width modulation is performed using at least one MOSFET driver. 
 
     
     
         20 . The system of  claim 1  further comprising:
 a means for clamping voltage of the motor at maximum voltage.