Control system for regulating motor speed
First Claim
1. A control system for regulating the speed of a motor having a rotatable rotor and windings that define poles of the motor, the control system comprising:
- a variable frequency drive that produces a drive signal that is provided to the windings of the motor to cause rotation of the rotor;
speed means for providing a speed signal that indicates the actual speed of the rotor;
monitor means for receiving the speedsignal and generating monitor signals that indicate motor performance relative to a speed profile of desired ;
motor speed during operation of the motor; and
control means for receiving the monitor signals and comparing the monitor signals with predetermined expected values, and for indicating a failure condition if an unexpected value is obtained and if the unexpected value persists for greater than a predetermined time interval.
1 Assignment
0 Petitions
Accused Products
Abstract
A motor control system accurately and reliably controls the speed of a motor so that the motor operates in accordance with a predetermined motor speed profile, and therefore does not exceed a predetermined safe speed, decelerates at a controlled rate, maintains a safe minimum speed, and does not turn in reverse. If the motor operates out of these limits, a malfunction is indicated and the control system halts operation of the motor. The motor speed is determined using an electronic tachometer that analyzes the current in at least two phases of the motor to provide extremely precise and reliable velocity information for the motor.
-
Citations
20 Claims
-
1. A control system for regulating the speed of a motor having a rotatable rotor and windings that define poles of the motor, the control system comprising:
-
a variable frequency drive that produces a drive signal that is provided to the windings of the motor to cause rotation of the rotor; speed means for providing a speed signal that indicates the actual speed of the rotor; monitor means for receiving the speed signal and generating monitor signals that indicate motor performance relative to a speed profile of desired ;
motor speed during operation of the motor; andcontrol means for receiving the monitor signals and comparing the monitor signals with predetermined expected values, and for indicating a failure condition if an unexpected value is obtained and if the unexpected value persists for greater than a predetermined time interval. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17)
-
-
18. A control system for regulating the speed of a motor, comprising:
-
an electronic tachometer coupled to the motor, said electronic tachometer producing a tachometer output that represents the speed of the motor; a monitor that receives said tachometer output and stores in memory a motor speed profile that represents desired motor speed during operation of the motor, said monitor comparing said tachometer output with said motor speed profile, and producing an error signal if a difference between said tachometer output and said motor speed profile exceeds predetermined expected values; and
,a timer coupled to receive said error signal and that indicates a failure condition if an unexpected value is obtained and persists for greater than a predetermined time interval. - View Dependent Claims (19)
-
-
20. A control system for regulating the speed of a motor having a rotatable rotor and windings that define poles of the motor, said control system comprising:
-
a variable frequency drive that produces a drive signal that is provided to the windings of the motor to cause rotation of the motor; a computer that controls operation of said variable frequency drive to run, accelerate, decelerate the motor within a predetermined motor speed profile; an electronic tachometer that electronically taps at least two windings of the motor and that produces at least one pulsed output signal that represents change of polarity of current of a phase of the motor and at least one output signal that indicates direction of rotation of the rotor; and control logic, coupled to receive said output signals from said electronic tachometer, that stores in memory a motor speed profile that represents desired motor speed during operation of the motor, including error bounds for each of desired acceleration and deceleration, compares motor speed to said motor speed profile that represents desired motor speed during operation of the motor, produces an error signal if a difference between said tachometer output and said motor speed profile exceeds said error bounds, and, indicates a failure condition an unexpected value is obtained and persists greater than a predetermined time interval.
-
Specification