Soft start motor control system for an irrigation system

Abstract

An irrigation system broadly comprising a number of irrigation spans and a control system configured to operate single speed drive motors of the irrigation spans in a start-up mode, full speed mode, and wind-down mode. In the start-up mode, the motor controller gradually increases the drive motor speed from 0 rpms to a full speed by ramping a voltage applied to the drive motor from a starting voltage to a full speed voltage according to a start-up voltage profile over a start-up time interval. In the full speed mode, the motor controller operates the drive motor at a full speed voltage. In the wind-down mode, the motor controller gradually decreases the drive motor speed from full speed to 0 rpms by ramping the voltage applied to the drive motor from the full speed voltage to an ending voltage according to a wind-down voltage profile over a wind-down time interval.

1 . A control system for controlling a single-speed motor, the control system being configured to operate the single-speed motor in:
 a start-up mode in which the control system gradually increases a speed of the single-speed motor from 0 rpms to a full speed;   a full speed mode in which the speed of the single-speed motor is the full speed; and   a wind-down mode in which the control system gradually decreases the speed of the single-speed motor from the full speed to 0 rpms.   
     
     
         2 . The control system of  claim 1 , wherein the control system initiates the start-up mode at a pre-set starting voltage less than a full speed voltage. 
     
     
         3 . The control system of  claim 2 , wherein the control system actively ramps applied voltage in the start-up mode from the starting voltage to the full speed voltage. 
     
     
         4 . The control system of  claim 3 , wherein the control system ramps applied voltage in the start-up mode from the pre-set starting voltage to the full speed voltage according to a pre-determined voltage profile. 
     
     
         5 . The control system of  claim 1 , wherein the control system operates the single-speed motor in the start-up mode for a pre-set amount of time. 
     
     
         6 . The control system of  claim 1 , wherein the control system initiates the start-up mode at a non-zero torque. 
     
     
         7 . The control system of  claim 1 , wherein a parameter of the start-up mode is at least partially determined according to at least one of a motor size and a motor speed rating. 
     
     
         8 . The control system of  claim 1 , wherein the control system terminates the wind-down mode at a pre-set ending voltage less than the full speed voltage. 
     
     
         9 . The control system of  claim 8 , wherein the control system actively ramps applied voltage in the wind-down mode from the full speed voltage to the pre-set ending voltage. 
     
     
         10 . The control system of  claim 9 , wherein the control system ramps applied voltage from the full speed voltage to the pre-set ending voltage according to a pre-determined voltage profile. 
     
     
         11 . The control system of  claim 1 , wherein the control system operates the single-speed motors in the wind-down mode for a pre-set amount of time. 
     
     
         12 . The control system of  claim 1 , wherein the control system terminates the wind-down mode at a non-zero torque. 
     
     
         13 . The control system of  claim 1 , a parameter of the wind-down mode being at least partially determined according to at least one of a motor size and a motor speed rating. 
     
     
         14 . The control system of  claim 1 , the control system including a plurality of controllers configured to operate a plurality of single-speed motors. 
     
     
         15 . The control system of  claim 14 , the control system being configured to operate at least one of the single-speed motors only in the full speed mode. 
     
     
         16 . The control system of  claim 14 , the control system being configured to operate at least two of the plurality of single-speed motors in the start-up mode, full speed mode, and wind-down mode and at least two of the plurality of single-speed motors only in the full speed mode. 
     
     
         17 . The control system of  claim 14 , the control system being configured to initiate the start-up mode for one of the plurality of single-speed motors upon receiving an alignment signal indicating a misalignment associated with the one of the plurality of single-speed motors. 
     
     
         18 . The control system of  claim 14 , the control system being configured to initiate the wind-down mode for one of the plurality of single-speed motors upon receiving an alignment signal indicating an alignment associated with the one of the plurality of single-speed motors. 
     
     
         19 . A control system for controlling a plurality of single-speed motors of an irrigation system, the control system being configured to operate at least some of the plurality of single-speed motors in:
 a start-up mode in which the control system gradually increases a speed of one of the plurality of single-speed motors from 0 rpms to a full speed;   a full speed mode in which the speed of the single-speed motor is the full speed; and   a wind-down mode in which the control system gradually decreases the speed of the one of the single-speed motors from the full speed to 0 rpms,   the control system being configured to initiate the start-up mode for the one of the plurality of single-speed motors upon receiving an alignment signal indicating a misalignment associated with the one of the plurality of single-speed motors,   the control system being configured to initiate the wind-down mode for the one of the plurality of single-speed motors upon receiving an alignment signal indicating an alignment associated with the one of the plurality of single-speed motors.   
     
     
         20 . A method of controlling a single-speed motor, the method comprising the steps of:
 gradually ramping a voltage applied to the single-speed motor from a pre-set starting voltage to a full speed voltage over a pre-set start-up time duration so as to gradually increase a speed of the single-speed motor from 0 rpms to a full speed;   applying the full speed voltage to the single-speed motor in a full speed mode; and   gradually ramping the voltage applied to the single-speed motor from the full speed voltage to a pre-set ending voltage over a pre-set wind-down time duration so as to gradually decrease the speed of the single-speed motor from the full speed to 0 rpms.