Automatic load seeking control for a multitorque motor

• US 4,413,218 A
• Filed: 06/24/1980
• Issued: 11/01/1983
• Est. Priority Date: 04/06/1979
• Status: Expired due to Term

• Current Assignee: Noel R. Taylor, Paul A. Taylor
• Original Assignee: CMD Enterprises, Inc.
• Inventors: Taylor, Paul A., Taylor, Noel R.
• Primary Examiner(s): Smith, Jr., David
• Application Number:
  US06/162,475
• Time in Patent Office: 1,225 Days
• Field of Search: 318/771, 318/778, 417/12, 417/45, 417/53
• US Class Current: 318/771
• CPC Class Codes: F04B 2203/0208 Power
• CPC Class Codes: F04B 49/06 Control using electricity regulating by means of floats actuating electric switches F04B49/04
• CPC Class Codes: H02P 25/18 with arrangements for switching the windings, e.g. with mechanical switches or relays

Abstract

Method and apparatus for matching the power output of a multitorque motor with the torque requirement of a connected load device. The stator windings of the motor are automatically connected in various different configurations to provide the optimum motor torque demanded by a connected load device which imposes varying load conditions on the motor. A novel control circuitry is connected between the motor starter and the motor stators. The control measures the power drawn by the motor stators and selects the most optimum configuration thereof which meets the changing torque requirements of the connected load device. This selection of optimum stator winding configurations commensurate with torque demand operates the motor in the lowest possible torque mode, which is considered the best electrical and mechanical operation of the motor and connected load device.

Claims

1. In a conveyor apparatus which conveys material from one location to another, wherein the mass of the conveyed material varies from one to another time interval, a three phase motor connected to move said conveyor, said motor having an automatic load seeking control circuitry for changing the stator winding of the motor from a high speed, high torque to a low speed, low torque configuration, comprising:

a motor starter means for connecting each stator winding to a source of current;

circuit means, including a first conductor means, for connecting the stator windings into a Y configuration;

sensor means responsive to a predetermined maximum average current flow which is actuated after said average current flow has occurred during a first time interval;

circuit means, including a second conductor means for connecting the stator windings into a Δ

configuration when said second conductor means is energized;

means by which said sensor means, when actuated, deenergizes said first conductor means and thereafter energizes said second conductor means;

a timer device connected to cause said second conductor means to be de-energized and said first conductor means to be energized a finite interval of time following energization of said second conductor means;

said starter means includes circuit means by which said stator windings are selectively connected in one of said Y and Δ

configuration to thereby enable the motor to start in either a high torque or a low torque mode;

so that the motor can be started in Y or Δ

configuration, and thereafter, said first and second conductor means will automatically change the winding configuration to either a high speed, high torque or low speed, low torque configuration depending upon the load imposed upon the motor.

2. In a prime mover apparatus having a multitorque motor which is connected to a mechanical load which varies in torque requirements from one time interval to another time interval, said motor having a stator connectable in either of Y, Δ

Y, and Δ

configuration, the improvement comprising;

first circuit means for connecting the stator in Y configuration when said first circuit means is energized;

said first circuit means includes a first sensor means for determining the current flow through said Y connected stators and for disconnecting said Y connected stator when the current flow through said Y connected stator exceeds a first maximum value during a first time interval;

second circuit means for connecting the stator in Δ

Y configuration when said first circuit means is disconnected by said first sensor means;

said second circuit means includes a first timer means by which said second circuit means disconnects said Δ

Y configuration after a predetermined time interval has expired, and said first circuit means concurrently connects said stator in the Y configuration;

third circuit means and a second sensor means, said second sensor means measures the current flow through said Δ

Y connected stators and causes said second circuit means to disconnect said Δ

Y configuration while concurrently causing said third circuirt means to connect said stators in Δ

configuration when the average current flow through said Δ

Y stators exceeds a second maximum value;

said third circuit means further includes a second timer by which current flow to the Δ

connected stator is discontinued by said third circuit means, while said second circuit means concurrently connects the stator in Δ

Y configuration after a preselected time interval has expired;

means providing current flow to said first, second, and third circuit means so that said stator can be connected to a suitable current supply; and

starter means including a starting mode circuit by which said stators of said motor are selectively connected in either of Y and Δ

configuration so that the motor starts in either of a low or high torque configuration and thereafter seeks to connect the stator in one of Y, Y Δ

, and Δ

winding configuration in accordance with the load imposed upon the motor;

said mechanical load is a variable pitch propeller connected to be driven by the output shaft of the motor;

a heat exchanger connected to exchange heat energy between fluid flowing therethrough and ambient air, means mounting said propeller to force ambient air across said heat exchanger in proportion to the propeller pitch, means measuring the temperature of the fluid flowing through the radiator and changing the propeller pitch in proportion to the magnitude of the measured temperature;

so that as the temperature of the fluid increases, the mass flow of ambient air changes proportionally, which causes the motor stator windings to be connected in the most optimum configuration for the torque load of the propeller.

3. In a prime mover apparatus having a multitorque motor which is connected to a mechanical load which varies in torque requirements from one time interval to another time interval, said motor having a stator connectable in either of Y, Δ

Y, and Δ

configuration, the improvement comprising;

first circuit means for connecting the stator in Y configuration when said first circuit means is energized;

said first circuit means includes a first sensor means for determining the current flow through said Y connected stators and for disconnecting said Y connected stator when the current flow through said Y connected stator exceeds a first maximum value during a first time interval;

second circuit means for connecting the stator in Δ

Y configuration when said first circuit means is disconnected by said first sensor means;

said second circuit means includes a first timer means by which said second circuit means disconnects said Δ

Y configuration after a predetermined time interval has expired, and said first circuit means concurrently connects said stator in the Y configuration;

third circuit means and a second sensor means, said second sensor means measures the current flow through said Δ

Y connected stators and causes said second circuit means to disconnect said Δ

Y configuration while concurrently causing said third circuit means to connect said stators in Δ

configuration when the average current flow through said Δ

Y stators exceeds a second maximum value;

said third circuit means further includes a second timer by which current flow to the Δ

connected stator is discontinued by said third circuit means, while said second circuit means concurrently connects the stator in Δ

Y configuration after a preselected time interval has expired;

means providing current flow to said first, second, and third circuit means so that said stator can be connected to a suitable current supply; and

starter means including a starting mode circuit by which said stators of said motor are selectively connected in either of Y and Δ

configuration so that the motor starts in either of a low or high torque configuration and thereafter seeks to connect the stator in one of Y, YΔ

, and Δ

winding configuration in accordance with the load imposed upon the motor;

said mechanical load is a conveyor means, said motor has an output shaft connected to drive the conveyor means, so that as the material being transported by the conveyor means changes in weight, the motor stator winding configuration changes to provide the most optimum torque mode.

4. In a prime mover apparatus having a multitorque motor which is connected to a mechanical load which varies in torque requirements from one time interval to another time interval, said motor having a stator connectable in either of Y, Δ

Y, and Δ

configuration, the improvement comprising;

first circuit means for connecting the stator in Y configuration when said first circuit means is energized;

said first circuit means includes a first sensor means for determining the current flow through said Y connected stators and for disconnecting said Y connected stator when the current flow through said Y connected stator exceeds a first maximum value during a first time interval;

second circuit means for connecting the stator in Δ

Y configuration when said first circuit means is disconnected by said first sensor means;

said second circuit means includes a first timer means by which said second circuit means disconnects said Δ

Y configuration after a predetermined time interval has expired, and said first circuit means concurrently connects said stator in the Y configuration;

third circuit means and a second sensor means, said second sensor means measures the current flow through said Δ

Y connected stators and causes said second circuit means to disconnect said Δ

Y configuration while concurrently causing said third circuit means to connect said stators in Δ

configuration when the average current flow through said Δ

Y stators exceeds a second maximum value;

said third circuit means further includes a second timer by which current flow to the Δ

connected stator is discontinued by said third circuit means, while said second circuit means concurrently connects the stator in Δ

Y configuration after a preselected time interval has expired;

means providing current flow to said first, second, and third circuit means so that said stator can be connected to a suitable current supply; and

starter means including a starting mode circuit by which said stators of said motor are selectively connected in either of Y and Δ

configuration so that the motor starts in either of a low or high torque configuration and thereafter seeks to connect the stator in one of Y, Y Δ

, and Δ

winding configuration in accordance with the load imposed upon the motor;

said first sensor means and said second sensor means are each thermally actuated switch means which are actuated when the current flow through the stator generates sufficient heat to actuate said thermally actuated switch means;

the inherent time delay of said thermally actuated switch means provides said first time interval.

5. A load seeking control device for a multiphase electric motor which is subjected to a varying load condition of first, second, and third magnitudes, respectively, during time intervals of 1, 2, and 3, respectively;

means by which the stators of said motor can be connected in either of Y, Δ

Y, and Δ

configuration, respectively, to provide a low, medium, and high torque, respectively.

a starter means for starting said motor;

first circuit means by which said motor is connected in Y configuration;

second circuit means, including a first current flow sensor, by which said motor is connected in Δ

Y when the average current flow to the Y connected motor exceeds the current rating of the Y connected stator over a first time interval;

a second current flow sensor by which said motor is connected in Δ

when the average current flow to the motor exceeds the current rating of the Y Δ

connected stator over another time interval;

said starter means includes a starting mode circuit by which said stators of said motor are selectively connected in either of Y and Δ

configuration so that the motor starts in either of a low or high torque configuration and thereafter seeks to connect the stator in one of Y, Y Δ

, and Δ

winding configuration in accordance with the load imposed upon the motor;

circuit means, including a first timer, by which said motor is changed from Y Δ

to Y should the average current flow assume a value below said current rating of said Y Δ

connected stator;

circuit means, including a timer, by which said motor is changed from Δ

to Y Δ

should the current flow assume a value below said current rating of said Δ

connected stator;

whereby said motor operates in Y, Δ

Y, or Δ

configuration according to the power output of the motor;

said varying load is a variable pitch propeller, means by which said propeller is connected to the output shaft of the motor;

a heat exchanger connected to exchange heat energy between fluid flowing therethrough and ambient air, means mounting said propeller to force ambient air across said heat exchanger in proportion to the propeller pitch, means measuring the temperature of the fluid flowing through the radiator and changing the propeller pitch proportional to the measured temperature;

so that as the temperature of the fluid increases, the mass flow of ambient air changes proportionally, which causes the motor stator windings to be connected in the most optimum configuration for the torque load of the propeller.

6. A load seeking control device for a multiphase electric motor which is subjected to a varying load condition of first, second, and third magnitudes, respectively, during time intervals of 1, 2, and 3, respectively;

means by which the stators of said motor can be connected in either of Y, Δ

Y, and Δ

configuration, respectively, to provide a low, medium, and high torque, respectively;

a starter means for starting said motor;

first circuit means by which said motor is connected in Y configuration;

second circuit means, including a first current flow sensor, by which said motor is connected in Δ

Y when the average current flow to the Y connected motor exceeds the current rating of the Y connected stator over a first time interval;

a second current flow sensor by which said motor is connected in Δ

when the average current flow to the motor exceeds the current rating of the Y Δ

connected stator over another time interval;

said starter means includes a starting mode circuit by which said stators of said motor are selectively connected in either of Y and Δ

configuration so that the motor starts in either of a low or high torque configuration and thereafter seeks to connect the stator in one of Y, Y Δ

, and Δ

winding configuration in accordance with the load imposed upon the motor;

circuit means, including a first timer, by which said motor is changed from Y Δ

to Y should the average current flow assume a value below said current rating of said Y Δ

connected stator;

circuit means, including a timer, by which said motor is changed from Δ

to Y Δ

should the current flow assume a value below said current rating of said Δ

connected stator;

whereby said motor operation in Y, Δ

Y, or Δ

configuration according to the power output of the motor;

said varying load is a conveyor means, said motor has an output shaft connected to drive the conveyor means, so that as the material being transported by the conveyor means changes in weight, the motor stator winding configuration changes to provide the most optimum torque mode.

7. Method of operating a mechanical device which is powered by a three phase motor, and wherein a variable mechanical load is imposed upon the motor by the mechanical device, comprising the following steps:

(1) connecting the stator windings of the motor in a Y configuration by connecting each of the stator windings to a set of contacts and connecting the contacts to a source of current such that the current flows through each winding and to a common junction;

(2) connecting each of the stator windings of the motor in a Δ

configuration by attaching one side of each stator winding to a set of contacts and connecting the contacts to a source of current such that the current flows in Δ

configuration through the windings;

(2a) determining the starting torque mode required to accommodate said variable mechanical load, and selecting one of the torque modes of steps (1) and (2) which most nearly matches the mechanical load;

(3) starting the motor by connecting the stator windings as set forth in step (2a); and

thereafter;

(4) measuring the current flow through the stator windings;

the thereafter,

(5) opening the contacts of step (1) and closing the contacts of step (2) when the motor is connected in the configuration of step (1) and the current in step (4) exceeds a predetermined average value;

(6) simultaneously commencing a timer with the closing of the contacts of step (2); and

,

(7) using the timer to open the contacts of step (2) and close the contacts of step (1) after a set time has lapsed;

(8) connecting the output shaft of the motor to power a conveyor means which transports a mass from one location to another, so that as the mass changes in weight, the motor stator is connected in the appropriate torque mode for efficiently moving the mass by the conveyor.

8. Method of operating a mechanical device which is powered by a three phase motor, and wherein a variable mechanical load is imposed upon the motor by the mechanical device, comprising the following steps:

(1) connecting the stator windings of the motor in a Y configuration by connecting each of the stator windings to a set of contacts and connecting the contact to a source of current such that the current flows through each winding and to a common junction;

(2) connecting each of the stator windings of the motor in a Δ

configuration by attaching one side of each stator winding to a set of contacts and connecting the contacts to a source of current such that the current flows in Δ

configuration through the windings;

(2a) determining the starting torque mode required to accommodate said variable mechanical load, and selecting one of the torque modes of steps (1) and (2) which most nearly matches the mechanical load;

(3) starting the motor by connecting the stator windings as set forth in step (2a); and

thereafter;

(4) measuring the current flow through the stator windings; and

thereafter,

(5) opening the contacts of step (1) and closing the contacts of step (2) when the motor is connected in the configuration of step (1) and the current in step (4) exceeds a predetermined average value;

(6) simultaneously commencing a timer with the closing of the contacts of step (2);

(7) using the timer to open the contacts of step (2) and close the contacts of step (1) after a set time has lapsed;

(8) connecting the output shaft of the motor to rotate a variable pitch propeller;

(9) changing the propeller pitch from one time interval to another time interval;

whereupon said controller connects the motor stator windings in the most optimum torque mode to supply the varying power requirements of the propeller.

9. A load seeking control device for a multiphase electric motor which is subjected to a varying load condition of first, second, and third magnitudes, respectively, during time intervals of 1, 2, and 3, respectively;

means by which the stators of said motor can be connected in either of Y, Δ

Y, and Δ

configuration, respectively, to provide a low, medium, and high torque, respectively;

a starter means for starting said motor;

first circuit means by which said motor is connected in Y configuration;

second circuit means, including a first current flow sensor, by which said motor is connected in Δ

Y when the average current flow to the Y connected motor exceeds the current rating of the Y connected stator over a first time interval;

a second current flow sensor by which said motor is connected in Δ

when the average current flow to the motor exceeds the current rating of the Y Δ

connected stator over another time interval;

said starter means including a starting mode circuit by which said stators of said motor are selectively connected in either of Y and Δ

configuration so that the motor starts in either of a low or high torque configuration and thereafter seeks to connect the stator in one of Y, Y Δ

, and Δ

winding configuration in accordance with the load imposed upon the motor;

circuit means, including a first timer, by which said motor is changed from Y Δ

to Y should the average current flow assume a value below said current rating of said Y Δ

connected stator;

circuit means, including a timer, by which said motor is changed from Δ

to Y Δ

should the current flow assume a value below said current rating of said Δ

connected stator;

whereby said motor operates in Y, Δ

Y, or Δ

configuration according to the power output of the motor;

said load is a variable pitch propeller which forces one fluid to flow in heat exchange relationship to another fluid;

means by which the pitch of said propeller is changed in proportion to the temperatures of said second fluid;

the variation in the mass flow of said one fluid being the recited variation in the mechanical load;

said first, second, and third circuit means, respectively, changes the stator to the Y, Δ

Y, and Δ

configuration, respectively, to cause the current flow through the motor to be equal to the rated motor output for Y, Δ

Y, and Δ

configuration.