MOTOR CONTROLLER AND RELATED METHOD

• US 20120086382A1
• Filed: 05/12/2010
• Published: 04/12/2012
• Est. Priority Date: 05/12/2009
• Status: Active Grant

• Current Assignee: Raymond John Peto
• Original Assignee: Raymond John Peto
• Inventors: Peto, Raymond John
• Granted Patent: US 8,796,966 B2
• Time in Patent Office: Days
• US Class Current: 318/729
• CPC Class Codes: H02M 1/0006 Arrangements for supplying an adequate voltage to the control circuit of converters
• CPC Class Codes: H02M 1/4225 using a non-isolated boost converter
• CPC Class Codes: H02M 5/458 using semiconductor devices only
• CPC Class Codes: H02P 23/26 Power factor control [PFC]
• CPC Class Codes: Y02B 70/10 Technologies improving the efficiency by using switched-mode power supplies [SMPS], i.e. efficient power electronics conversion e.g. power factor correction or reduction of losses in power supplies or efficient standby modes

Abstract

The present invention relates to a motor controller and related method. The invention is particularly well suited for use with an alternating current (AC) induction motor. Previously motor controllers did not take into account the combined effect a control circuit and controlled motor, had upon a mains supply and more particularly their separate and combined effect upon the power factor of an alternating current. The invention solves this problem by providing a motor controller which modifies an input current to an alternating current (AC) motor. The motor controller comprises: a power input rectifier; a low voltage power supply; a variable output voltage circuit for adjusting a drive output voltage circuit; and a control circuit arranged to control the variable output voltage circuit and to provide timed waveforms to the drive output voltage circuit.

Claims

1. A motor controller which modifies an input current to an alternating current (AC) motor, where said motor has at least one winding, the motor controlling comprising:

a power input rectifier;

a low voltage power supply to supply power to a control circuit;

a variable output voltage circuit for providing a variable DC voltage to the drive output voltage circuit to provide power to the at least one winding; and

a control circuit arranged to control the variable output voltage circuit and to provide timed waveforms to the drive output voltage circuit.

2. A motor controller according to claim 1 wherein the variable output voltage circuit simultaneously provides a power factor corrected input current waveform.

3. A motor controller according to claim 1 wherein the drive output voltage circuit is, arranged to switch the voltage at an adjustable repetition rate in synchronism with the variable voltage provided to the at least one winding.

4. A motor controller according to claim 1 including a means for modifying an input of the variable output voltage circuit, so that a near unity power factor is presented to a mains supply.

5. A motor controller according to claim 1 wherein the drive output voltage circuit is arranged, whereby in use output capacitors are arranged to apply, a slew rate limited wave voltage to the motor.

6. A motor controller according to claim 1, wherein the drive output voltage circuit is arranged, whereby in use, the wave is from the group comprising:

sine waves, square waves, saw tooth waves, variants and combinations of the aforesaid waves.

11. A motor controller according to claim 1 has a single phase controller which is arranged to switch an input current to zero for a predetermined and variable time duration.

15. A motor controller according to claim 1 wherein a capacitive load, in use, is connected across at least one of the windings.

16. A motor controller according to claim 1 including a resistive load in a series with the motor.

17. A motor controller according to claim 1 including a means for providing harmonic information which can be used to provide an indication of the power factor.

18. A motor controller according to claim 1 comprising an input for operating with two and three phase power supplies.

19. A motor controller according to claim 1 including a logic controller which is in the form of a solid state device, and includes a microprocessor.

20. A motor controller according to claim 1 which is potted and smaller size that the motor.

21. A motor controller according to claim 1 which is included in equipment in the group comprising:

pumps, compressors, refrigerators, air conditioner, fans, escalators, conveyors, machines, washing machines, spin driers, tumble driers, food mixers, food processors, grinder, shoe polishers and ventilation fans.

22. A motor controller according to claim 1 which is included in a vehicle and is used to control the speed of the vehicle.

23. A motor controller according to claim 1 being less than 4 cm long, 3 cm wide and 2 cm thick.

24. A motor controller according to claim 1 having a volume less than of 3.0, preferably less than 2.0 and most preferably less than 1.0×

10<sup>−

6</sup> m³.

25. A motor controller according to claim 1 which is incorporated into a telemetric control network operating as part of a supervisory control and data acquisition system (SCADA).

26. A motor controller according to claim 1 has a memory which is able to receive updated control software.

28. A method of controlling a motor according to claim 26 wherein a power factor corrected current is applied to at least one winding.

7. A motor controller which modifies an input current to an alternating current (AC) motor, said motor has at least one winding, the motor controller comprising:

a power input rectifier, a low voltage power supply to supply voltage to a control circuit;

a variable output voltage circuit for adjusting maximum (or minimum) value of the drive output voltage supplied to the at least one winding;

a drive output voltage circuit to drive the motor and a control circuit arranged to control the variable output voltage circuit, and means to control the drive output voltage circuit so as to provide time varying waveforms to the output circuit.

10. A motor controller according to claim 7 wherein the drive output voltage circuit is arranged to switch the voltage at an adjustable repetition rate in synchronism with the variable voltage provided to the at least one winding.

8. A motor controller which modifies an input current to an alternating current (AC) motor, said motor has at least one winding, the motor in use adapted to be connected, in series, with said first input current and to derive a modified drive current waveform therefrom, the controller comprising:

a low voltage power supply;

a rectification circuit;

a variable voltage and power factor correction circuit;

a multiphase output circuit;

a control circuit arranged to control the variable voltage and power factor correction circuit and the multiphase output circuit being arranged so as to provide a modified drive output voltage which is variable.

9. A motor controller according to claim 8 wherein the modified drive output voltage is arranged to switch the voltage applied to the motor between a maximum (or minimum) including zero for a predetermined and variable time duration.

12. A motor controller according to claim 8 wherein there are at least two windings and a leading phase current is applied to a first winding of the motor;

and a different phase current is applied to second winding of the motor.

13. A motor controller according to claim 8 wherein a feedback loop includes a feedback controller providing a feedback signal of the drive waveform input into the variable voltage and power factor correction, in response to a variation in motor load.

14. A motor controller according to claim 13 wherein the feedback loop includes a pulse width modulator (PWM).

27. A method of controlling a motor comprising the steps of:

varying an input voltage and/or current;

selecting an instantaneous voltage according to the requirements of the motor and applying said instantaneous voltage to a desired winding of the motor.

29. A motor controller which modifies an input current to an alternating current (AC) motor, where said motor has at least one winding, the motor controller comprising:

a power input rectifier; and

output voltage circuit for providing a drive output; and

a control circuit arranged to control the drive output voltage to provide timed waveforms to the drive output voltage circuit;

the control circuit including a means for modifying an input operable to adjust the time waveforms so that a near unity power factor is presented to a mains supply.

30. The motor controller, according to claim 29 wherein the output voltage circuit is operable to provide the drive output voltage as a variable drive output voltage.

31. The motor controller according to claim 29, including a low voltage power supply to supply voltage to a control circuit.

32. A method of controlling a motor comprising the steps of:

modifying an input current to an alternating current (AC) motor, the motor having first and second windings, the steps comprising;

deriving a low voltage power supply;

rectifying said supply;

providing a reduced DC voltage while presenting an acceptable power factor to the supply, providing control and timing signals and providing a multiphase output stage so as to provide the modified drive voltage and current whose value is zero for a predetermined time duration (T).

33. A motor controller substantially as herein described and with reference to the drawings.

34. A method of controlling a motor substantially as herein described.