Single-phase induction motor safety controller

• US 5,670,858 A
• Filed: 10/07/1996
• Issued: 09/23/1997
• Est. Priority Date: 06/03/1991
• Status: Expired due to Fees

• Current Assignee: ENCON International, Inc., James H. Copeland III
• Original Assignee: Condyne Technology, Inc.
• Inventors: Heath, Gary
• Primary Examiner(s): Cabeca, John W.
• Application Number:
  US08/726,625
• Time in Patent Office: 351 Days
• Field of Search: 318/777, 318/768, 318/781, 318/786, 318/801, 318/803, 318/805, 318/806, 318/807, 318/808, 318/809, 318/810, 318/811, 318/599, 318/254, 307/234, 307/350, 307/362, 307/87, 307/311, 363/17, 363/18, 363/19, 363/21, 363/26, 363/23, 363/37, 363/89, 363/79, 363/56, 363/124, 363/126, 363/286, 363/53, 363/68, 323/345, 323/282, 323/323, 361/75, 361/96
• US Class Current: 318/768
• CPC Class Codes: H02H 7/08 for dynamo-electric motors
• CPC Class Codes: H02P 25/14 Universal motors H02P25/12 takes precedence

Abstract

An electronic control apparatus to operate an alternating current induction motor protecting same from power line blackouts, brownouts and providing self-adjusting, linearized, non-stepped reduced voltage output coinciding to work load to enhance efficiency, thereby reducing electrical energy used by the motor. This apparatus can be utilized in conjunction with a refrigerator, air conditioner or almost any home appliance to yield a substantial savings in electrical use.

Claims

1. An electronic control apparatus for automatically adjusting electrical input to a single phase alternating current (AC) induction motor running at constant RPM comprising:

means for sampling voltage input provided by an electrical source to the motor, said means being connected to an input line from the electrical source;

means for rectifying the sample voltage input taken from the electrical source to yield a rectified output voltage;

means for creating a fixed pulse indicating zero voltage crossing;

means for sampling current input being provided by the electrical source to the motor to create a time-variable pulse indicating zero current crossing, said time-variable pulse which triggers a monostable output voltage; and

means for adjusting voltage supplied to the motor by using the fixed pulse and the monostable output voltage.

2. The electronic control apparatus of claim 1 further comprising:

means for comparing the rectified voltage to a preset universal reference voltage provided by a regulator to detect voltage burnout conditions.

3. The electronic control apparatus of claim 1 further comprising:

means for comparing sampled current input to a preset reference current from the electrical power source to detect overcurrent conditions.

4. The electronic control apparatus of claim 2 further comprising:

means for comparing sampled current input to a preset reference current from the electrical power source to detect overcurrent conditions.

5. The electronic control apparatus of claim 1, further comprising:

means for delaying re-commencement of electrical power from the electrical power source after a voltage interruption caused when the voltage from the power source drops below a pre-set voltage.

6. The electronic control apparatus of claim 2, further comprising:

means for delaying re-commencement of electrical power from the electrical power source after a voltage interruption caused when the voltage from the power source drops below a pre-set voltage.

7. The electronic control apparatus of claim 3, further comprising:

means for delaying re-commencement of electrical power from the electrical power source after a voltage interruption caused when the voltage from the power source drops below a pre-set voltage.

8. The electronic control apparatus of claim 4, further comprising:

means for delaying re-commencement of electrical power from the electrical power source after a voltage interruption caused when the voltage from the power source drops below a pre-set voltage.

9. The electronic control apparatus of claim 1 wherein the means for sampling voltage input comprises a transformer which reduces line voltage through a full wave range rectifier, which in turn provides a rectified full wave signal to a direct current regulator.

10. The electronic control apparatus of claim 3 wherein the means for sampling current input to detect over-current conditions comprises a comparator connected between the motor and electrical power source which compares the current input to a reference current preset by a variable resistor.

11. The electronic control apparatus of claim 4 wherein the means for sampling current input to detect over-current conditions comprises a comparator connected between the motor and electrical power source which compares the current input to a reference current preset by a variable resistor.

12. The electronic control apparatus of claim 1 wherein the means for rectifying the sampled voltage input consists of a transformer which reduces line voltage to provide same to a full-wave bridge rectifier to yield a rectified full-wave signal.

13. The electronic control apparatus of claim 2 wherein the means for comparing the rectified voltage consists of a comparator that compares voltage output from the rectifier to a preset reference voltage provided by a regulator.

14. The electronic control apparatus of claim 3 wherein the means for comparing the sampled current input to preset reference current consists of a comparator which compares the current input to the preset current provided by a resistor network.

15. The electronic control apparatus of claim 4 wherein the means for comparing the sampled current input to preset reference current consists of a comparator which compares the current input to the preset current provided by a resistor network.

16. The electronic control apparatus of claim 5 wherein the means for delaying re-commencement of electrical power consists of a time delay circuit connected between an under-voltage detector and logic circuit.

17. The electronic control apparatus of claim 6 wherein the means for delaying re-commencement of electrical power consists of a time delay circuit connected between an under-voltage detector and logic circuit.

18. The electronic control apparatus of claim 7 wherein the means for delaying re-commencement of electrical power consists of a time delay circuit connected between an under-voltage detector and logic circuit.

19. The electronic control apparatus of claim 8 wherein the means for delaying re-commencement of electrical power consists of a time delay circuit connected between an under-voltage detector and logic circuit.

20. A method of continuously monitoring the minimum voltage and current requirements of an AC motor and providing those requirements to the motor, using an electronic control apparatus comprising a means for sampling voltage input provided by an electrical source to the motor, said means being connected to an input line from the electrical source;

a means for rectifying the sample voltage input taken from the electrical source to yield a rectified output voltage;

a means for creating a fixed pulse indicating zero voltage crossing;

a means for sampling current input being provided by the electrical source to the motor to create a time-variable pulse indicating zero current crossing, said time-variable pulse which triggers a fixed monostable output voltage; and

means for adjusting voltage supplied to the motor by using the fixed pulse indicating zero voltage crossing and the monostable output voltage, said method comprising the steps of;

sampling both incoming voltage and current provided by an electrical source to the motor;

determining by comparison to a preset reference voltage and current whether the incoming voltage and current are within limits for the motor;

supplying said voltage and current to the motor if the incoming voltage and current are determined to be within limits;

automatically continuously checking a load on the motor during its operation after the voltage and current are supplied; and

automatically continuously resetting the voltage and current supplied to the motor according to the load on the motor during its operation.