Method and apparatus for controlling an induction motor
First Claim
Patent Images
1. A controller for producing a constant output from a motor under varying load conditions, said controller comprising:
- a current sensor electrically connected to said motor to measure current flow to the motor;
a first control circuit connected to said current sensor to generate, based on said current flow, a current error; and
a second control circuit connected to said first control circuit to generate, based on the current error and a linear voltage-to-frequency relationship, a command voltage required to maintain said constant output.
4 Assignments
0 Petitions
Accused Products
Abstract
A method and apparatus for improving the efficiency of an induction motor used in fluid pump and blower applications including a controller that reduces the flux generated by the motor at less than maximum motor loads.
-
Citations
31 Claims
-
1. A controller for producing a constant output from a motor under varying load conditions, said controller comprising:
-
a current sensor electrically connected to said motor to measure current flow to the motor; a first control circuit connected to said current sensor to generate, based on said current flow, a current error; and a second control circuit connected to said first control circuit to generate, based on the current error and a linear voltage-to-frequency relationship, a command voltage required to maintain said constant output. - View Dependent Claims (2, 3, 4, 5, 6)
-
-
7. A controller for a motor used in a fluid system, the motor having a d.c. bus and at least one stator phase connected to said d.c. bus, said controller comprising:
-
drive signal means for producing a current flow in said stator phase such that said current flow varies in response to varying load conditions for said motor; monitoring means for monitoring said current flow; change signal means for producing a change signal related to changes in said current flow; manipulation means electrically connected to said change signal means and to said drive signal means for changing said electrical drive signal in response to said change signal; and means for reducing the flux generated by the controller for a commanded flow rate of fluid through the fluid system. - View Dependent Claims (8, 9, 10, 11)
-
-
12. A method of controlling a motor to produce a constant output under varying motor load conditions, the motor having at least one stator phase, said method comprising:
-
(A) determining a required motor output; (B) producing an electrical drive signal in said stator phase to generate said motor output; (C) determining variations in said motor load; and (D) changing said electrical drive signal in response to said variations in said motor load according to a linear voltage-to-frequency relationship to maintain said required motor output. - View Dependent Claims (13, 14, 15, 16, 17, 18, 19)
-
-
20. An air handling system comprising:
-
a blower including a motor having at least one stator phase, and a fan connected to the motor; and a controller for producing a constant output from said blower under varying load conditions, said controller including a current sensor electrically connected to said stator phase to measure a change in current flow in said stator phase in response to a change in the load on said blower, and a control circuit connected to said current sensor to generate, based on said change in current flow in said stator phase and a linear voltage-to-frequency relationship, a command voltage, and to generate, based in said command voltage, an updated drive current required to maintain said constant output. - View Dependent Claims (21, 22)
-
-
23. A method of controlling an air handling system having a blower including a motor having at least one stator phase, and a fan connected to the motor so that said motor is under a load, said method comprising:
-
(A) determining a required motor output; (B) producing an electrical drive signal in said stator phase to generate said motor output; (C) determining variations in said motor load; and (D) changing said electrical drive signal in response to said variations in said motor load according to a linear voltage-to-frequency relationship to maintain said required motor output. - View Dependent Claims (24, 25, 26, 27, 28, 29, 30, 31)
-
Specification