Motor controls, refrigeration systems and methods of motor operation and control

• US 5,125,067 A
• Filed: 02/27/1991
• Issued: 06/23/1992
• Est. Priority Date: 06/24/1974
• Status: Expired due to Term

• Current Assignee: General Electric Company
• Original Assignee: General Electric Company
• Inventors: Erdman, David M.
• Primary Examiner(s): Ro, Bentsu
• Application Number:
  US07/661,807
• Time in Patent Office: 482 Days
• Field of Search: 318/138, 318/254, 318/439, 388/934
• US Class Current: 388/811
• CPC Class Codes: F23N 2233/04 with variable speed
• CPC Class Codes: F23N 3/082 using electronic means
• CPC Class Codes: F25B 2600/021 Inverters therefor
• CPC Class Codes: F25B 49/025 Motor control arrangements
• CPC Class Codes: G05D 23/19 characterised by the use of electric means G05D23/1393 takes precedence
• CPC Class Codes: H02K 29/06 with position sensing devices H02K29/03 takes precedence
• CPC Class Codes: H02K 29/10 using light effect devices
• CPC Class Codes: H02P 2209/07 Trapezoidal waveform
• CPC Class Codes: H02P 6/085 in a bridge configuration
• CPC Class Codes: H02P 6/14 Electronic commutators
• CPC Class Codes: H02P 6/16 Circuit arrangements for detecting position
• CPC Class Codes: H02P 6/182 using back-emf in windings

Abstract

A method of operating a brushless motor having a stationary assembly with at least two different energizable windings for producing spaced apart magnetic fields in time sequence, and a rotor adapted to rotate in response to the magnetic fields. The method includes the steps of simulating rotor position in accordance with the back emf condition of at least one winding, energizing a selected one of the windings in accordance with the simulated rotor position, sensing an underspeed condition when the motor speed is less than a minimum value for a length of time, and preventing energization of any of the windings when the motor speed is less than the minimum value for the length of time. An electrically commutated motor controller apparatus controls the speed of a variable speed motor compressor driven by an electrically commutated motor. A controller circuit includes a circuit for producing feedback signals representative of a back emf of the motor. A compressor speed circuit generates actual compressor speed signals from the feedback signals produced by the controller circuit. A duty cycle generator produces a speed control signal as a function of the actual compressor speed signals, and the speed control signal is transmitted to the controller circuit for adjusting the speed of the electrically commutated motor driven compressor. Other motor controls, refrigeration systems and methods of control and operation are also disclosed.

Claims

1. A method of operating a compressor system driven by a brushless motor having a stationary assembly with at least two different energizable windings for producing spaced apart magnetic fields in time sequence, and a rotor adapted to rotate in response to the magnetic fields, the method comprising the steps of:

providing signals indicative of the rotational position of the compressor and the rotor;

energizing the windings in a predetermined sequence in response to said signals thereby to cause advancement of commutation of the windings by an angle alpha of from about five to about twenty-five electrical degrees to aid the build-up of current when the windings are energized during running condition of the motor and the compressor;

wherein the step of providing signals indicative of the rotational position of the compressor and the rotor includes the steps of

sensing a back emf signal indicative of the back emf condition of at least one winding;

integrating the back emf signal so sensed to a triggering point; and

producing each of said signals indicative of the rotational position of the compressor and the rotor when the triggering point is reached in the integrating step, the triggering point substantially establishing the angle alpha.

2. A method as set forth in claim 1 further comprising the steps of deriving a speed output from said signals indicative of the rotational position of the compressor and the rotor and regulating the energization of the windings in accordance with the speed output.

3. A method as set forth in claim 1 further comprising the steps of deriving a speed output from the signals indicative of the rotational position of the compressor and the rotor, providing a temperature control signal and regulating the energization of the windings in accordance with said speed output and said temperature control signal.

4. A refrigeration system comprising a compressor assembly including a compressor mechanism for circulating a refrigerant through an evaporator and a motor coupled with said compressor mechanism and comprising a stationary armature core, at least one energizable winding disposed on said armature core to produce at least one magnetic field, and a permanent magnet rotor adapted to rotate in response to the at least one magnetic field produced by said winding;

electronic commutating means for selectively switching a source voltage to energize, in sequence, different portions of said winding, said electronic commutating means including means responsive to a back emf signal from the winding to activate the switching;

temperature control means for providing an output as a function of temperature in the vicinity of said refrigeration system;

means for deriving a speed output from said means responsive to the back emf signal; and

means for regulating the energization of the winding in accordance with the speed output and the temperature control means.

5. A refrigeration system as set forth in claim 4 wherein said means responsive to the back emf signal includes means for integrating the back emf signal to a predetermined triggering point and means for producing a simulated relative position output when the predetermined triggering point is reached to activate the switching.

6. A refrigeration system as set forth in claim 4 further comprising means, connected to said electronic commutating means, for sensing an overvoltage condition when the source voltage is greater than a maximum value, and preventing energization of any of the portions of the winding when the overvoltage condition is sensed.

7. A refrigeration system as set forth in claim 4 further comprising means, connected to said electronic commutating means, for sensing an undervoltage condition when the source voltage is less than a minimum value, and preventing energization of any of the portions of the winding when the undervoltage condition is sensed.

8. A refrigeration system as set forth in claim 4 further comprising means responsive to the speed output for sensing an underspeed condition when the motor speed is less than a minimum value for a length of time, to prevent energization of any of the portions of the winding when the motor speed is less than the minimum value for the length of time.

9. A refrigeration system as set forth in claim 4 further comprising a hermetic enclosure with said compressor mechanism and said motor both sealed in said hermetic enclosure.

10. An electrically commutated motor controller apparatus for controlling the speed of a variable speed motor compressor driven by an electrically commutated motor comprising controller means for controlling the speed of the motor and means for producing feedback signals representative of a back emf of the motor, compressor speed means for generating actual compressor speed signals from said feedback signals produced by said controller means, and duty cycle generator means for producing a speed control signal as a function of the actual compressor speed signals, the speed control signal being transmitted to said controller means for adjusting the speed of the electrically commutated motor driven compressor.

11. Electrically commutated motor controller apparatus as set forth in claim 10 further comprising sensing means for sensing motor current, said sensing means connected to affect the speed control signal depending on the motor current.

12. Electrically commutated motor controller apparatus as set forth in claim 10 wherein said controller means includes means for receiving back emf signals from the electrically commutated motor.

13. Electrically commutated motor controller apparatus as set forth in claim 12 wherein said controller means also includes means connected to said means for receiving back emf signals for integrating the back emf signals to a triggering point to produce the feedback signals.

14. Electrically commutated motor controller apparatus as set forth in claim 10 wherein the motor has windings and said apparatus further comprises a capacitor connected to said controller means and unidirectional conduction means for returning to said capacitor, energy released by a decaying magnetic field of a winding of the motor when it is deenergized.

15. A refrigeration system comprising a compressor, an electronically commutated motor for driving said compressor with a variable speed, controller means for controlling the speed of said electronically commutated motor, said controller means producing feedback signals representative of a back emf of said motor, compressor speed means for generating actual compressor speed signals from said feedback signals produced by said controller means, and duty cycle generator means for producing a speed control signal as a function of said actual compressor speed signals, said speed control signal being transmitted to said controller means for adjusting the speed of said compressor driven by said electronically commutated motor.

16. A refrigeration system as set forth in claim 15 further comprising sensing means for sensing motor current, said sensing means connected to affect the speed control signal as a function of the motor current.

17. A refrigeration system as set forth in claim 15 wherein said controller means includes means for integrating the back emf to a triggering point to produce the feedback signals.

18. A refrigeration system as set forth in claim 15 wherein said motor has windings and said system further comprises a capacitor connected to said controller means, and unidirectional condition means for returning to said capacitor energy released by a decaying magnetic field of each of said windings of said motor when they are deenergized.

19. A refrigeration system for use with a power source and comprising a compressor assembly including a compressor mechanism for circulating a refrigerant through an evaporator and a motor coupled with said compressor mechanism and comprising a stator having a stationary armature core, at least one excitable winding disposed on said armature core to produce at least one magnetic field and having at least one back emf, and a permanent magnet rotor adapted to rotate in response to the at least one magnetic field produced by said winding;

electronic commutating means coupled to the power source for selectively switching a source voltage to energize, in sequence, different portions of said winding;

said electronic commutating means including means for producing a signal representative of the back emf of the motor winding, compressor speed means for generating an actual compressor speed output from the signal representative of the back emf, temperature control means for providing an output indicative of a desired temperature to be maintained by the refrigeration system, and regulator means responsive to the temperature control means output and the actual compressor speed output for controlling the stator winding energization in accordance with the desired temperature.

20. A method of controlling the speed of an electrically commutated motor compressor driven by an electrically commutated motor having windings, comprising the steps of generating a feedback signal from back emf signals from the motor indicative of actual compressor speed, producing a compressor speed signal representative of said back emf signals, generating therefrom a speed control signal having a level for application to an electrically commutated motor controller circuit, and modifying compressor speed in response to the level of said speed control signal.

21. A method as set forth in claim 20 wherein the step of generating a feedback signal from the back emf signals includes integrating the back emf signals to a triggering point and producing a simulated relative position output as the feedback signal when the triggering point is reached.

22. A method as set forth in claim 20 wherein energy for the motor is supplied from a source voltage, the method further comprising the steps of sensing an overvoltage condition when the source voltage is greater than a maximum value, and preventing energization of any of the windings when the overvoltage condition is sensed.

23. A method as set forth in claim 20 wherein energy for the motor is supplied from a source voltage, the method further comprising the steps of sensing an undervoltage condition when the source voltage is less than a minimum value, and preventing energization of any of the windings when the undervoltage condition is sensed.

24. A method as set forth in claim 20 further comprising the steps of sensing an underspeed condition when the compressor speed signal is less than a minimum value for a length of time lo prevent energization of any of the windings when the compressor speed signal is less than the minimum value for the length of time.

25. A method of operating a refrigeration system having a compressor mechanism for circulating a refrigerant through an evaporator and a motor coupled with the compressor mechanism and comprising a stationary armature core, at least one energizable winding disposed on the armature core to produce at least one magnetic field, and a rotor adapted to rotate in response to the at least one magnetic field produced by the winding, the method comprising the steps of:

commutating the motor electronically by selectively switching a source voltage to energize in sequence different portions of the winding;

responding to a back emf signal from the winding to activate the switching;

providing an output as a function of temperature in the vicinity of the refrigeration system;

deriving a speed output from the back emf signal; and

regulating the energization of the winding in accordance with the speed output and the temperature output.

26. A refrigeration system comprising a compressor assembly including a compressor mechanism for circulating a refrigerant through an evaporator and a variable speed motor coupled to said compressor mechanism;

means to develop a temperature signal responsive to the temperature being controlled by said refrigeration system; and

a hermetic enclosure with said compressor mechanism and said motor both sealed in said hermetic enclosure;

said motor comprising a stationary armature core with at least one energizable winding disposed on said armature core to produce at least one moving magnetic field;

a rotor coupled to said compressor mechanism and adapted to rotate in response to the at least one moving magnetic field produced by said winding, and position sensing means to provide a position signal responsive to the position of said rotor, and means for selectively energizing different portions of said winding to produce said moving magnetic field responsive to said position signal and said temperature signal to vary the speed of said compressor mechanism in response to changes in said temperature being controlled.

27. A refrigeration system as set forth in claim 26 further comprising means for sensing an underspeed condition when the motor speed is less than a minimum value for a length of time, to prevent energization of any of said portions of said winding when the motor speed is less than the minimum value for the length of time.

28. A refrigeration system as set forth in claim 26 wherein energy of the motor is supplied from a source voltage, the system further comprising means for sensing an overvoltage condition when the source voltage energizing said motor is greater than a maximum value, and for preventing energization of any of said portions of said winding when said overvoltage condition is sensed.

29. A refrigeration system as set forth in claim 26 wherein said position sensing means includes means for integrating a back emf signal from said winding to a predetermined triggering point, and means for producing a simulated relative position output when this predetermined triggering point is reached to control the movement of said moving magnetic field.

30. A refrigeration system as set forth in claim 26 further comprising sensing means for sensing motor current, said sensing means connected to the energizing means to affect the energization of said winding as a function of said motor current.

31. A refrigeration system comprising a compressor assembly including a compressor mechanism for circulating a refrigerant through a condenser and an evaporator, and a motor having a rotatable shaft connected to said compressor mechanism and a stationary assembly having a plurality of windings adapted to be energized in at least one preselected sequence, and a rotor in selective magnetic coupling relation with said windings;

a hermetically sealed enclosure surrounding both said motor and said compressor mechanism with said rotor being directly coupled by said shaft to said compressor mechanism inside said hermetically sealed enclosure;

temperature control means for providing a temperature signal as a function of temperature in the vicinity of the refrigeration system;

means responsive to the position of the rotor for deriving an electrical position signal from said motor; and

electronic means responsive to the position signal and said temperature signal for selectively energizing said windings in the at least one preselected sequence so that said rotor rotates with a variable speed, said compressor mechanism thereby providing a variable refrigerant circulation to control the temperature in the vicinity of the refrigeration system.

32. A refrigeration system as set forth in claim 31 further comprising a capacitor connected to said electronic means, and unidirectional conduction means for returning to said capacitor energy released by a decaying magnetic field of each of said windings of said motor when said windings are deenergized.

33. A control system for a compressor assembly including a compressor mechanism for circulating a refrigerant through an evaporator and a motor coupled to said compressor mechanism and having a stator assembly having a plurality of windings adapted to be electronically energized in at least one preselected sequence, and a rotor in selective magnetic coupling with said windings, the control system comprising electronic means for selectively connecting a source voltage to the windings in the at least one preselected sequence to energize said windings thereby effecting the rotation of said rotor, means responsive to a back emf signal from said windings for controlling said electronic means for selectively connecting the source voltage to the windings;

temperature control means for providing a temperature signal as a function of temperature in a space to be controlled;

means for deriving a speed control signal from said means responsive to a back emf signal; and

means for regulating the energization of said windings by said electronic means in accordance with said speed control signal and said temperature signal.

34. A control system as set forth in claim 33 further comprising means for sensing an overvoltage condition when the source voltage is greater than a maximum value and for preventing energization of any of the windings when the overvoltage condition is sensed.

35. A control system as set forth in claim 33 further comprising means, connected to said electronic means, for sensing an undervoltage condition when the source voltage is less than a minimum value, and preventing energization of any of the windings when the undervoltage condition is sensed.

36. A refrigeration system comprising a compressor assembly including a compressor mechanism for circulating a refrigerant through an evaporator;

a motor coupled to said compressor mechanism and comprising a stationary assembly having a plurality of windings adapted to be energized in at least one preselected sequence, and a rotor in selective magnetic coupling with said windings;

a hermetically sealed enclosure surrounding said motor and said compressor mechanism, wherein said rotor is coupled with said compressor mechanism inside said hermetically sealed enclosure;

electronic means for selectively switching a source voltage to energize said windings in the at least one preselected sequence to effect the rotation of the rotor, means responsive to a back emf signal from said windings for controlling said electronic means for selectively connecting the source voltage to the windings;

temperature control means for providing a temperature signal as a function of the temperature in the vicinity of said refrigeration system;

means for deriving a speed signal from said means responsive to the back emf signal; and

means connected to said electronic means for controlling the energization of said windings by said electronic means in response to the speed signal and said temperature control means.

37. A refrigeration system for use with an electric power source and comprising a compressor assembly including a compressor mechanism for circulating a refrigerant through an evaporator;

a motor coupled to said compressor mechanism and comprising a stationary assembly having a plurality of windings adapted to be electronically commutated in at least one preselected sequence, and a rotor in selective magnetic coupling relation with said windings; and

electronic commutating means for selectively switching a source voltage to commutate said windings in the at least one preselected sequence to energize said windings thereby effecting the rotation of the rotor, said electronic commutating means including means for producing a signal representative of a back emf of the motor windings, compressor speed means for generating a compressor speed output signal from the signal representative of the back emf, temperature control means for providing an output responsive to variation in temperature from a desired temperature to be maintained by the refrigeration system, and means responsive to the temperature control means output and the compressor speed output signal for controlling the energization of said windings to provide the desired temperature.

38. A refrigeration system comprising a compressor assembly including a compressor mechanism for circulating a refrigerant through an evaporator and a variable speed electronically commutated motor coupled to said compressor mechanism;

means to develop a temperature signal responsive to the temperature being controlled by said refrigeration system; and

a hermetic enclosure with said compressor mechanism and said motor both sealed in said hermetic enclosure;

said motor comprising a stationary armature core with at least one energizable winding disposed on said armature core to produce at least one moving magnetic field;

a rotor coupled to said compressor mechanism and including a permanent magnet element in selective magnetic coupling relation with said windings, said rotor adapted to rotate in response to the at least one moving magnetic field produced by said winding, and rotation sensing means to provide a rotation signal responsive to the rotation of said rotor, and means for selectively energizing different portions of said winding to produce said moving magnetic field responsive to said rotation signal and said temperature signal to vary the speed of said compressor mechanism in response to changes in said temperature being controlled.

39. A refrigeration system comprising a compressor assembly including a compressor mechanism for circulating a refrigerant through a condenser and an evaporator, and an electronically commutated motor having a rotatable shaft connected to said compressor mechanism and a stationary assembly having a plurality of windings adapted to be energized in at least one preselected sequence, and a rotor including a permanent magnetic element in selective magnetic coupling relation with said windings;

a hermetically sealed enclosure surrounding both said motor and said compressor mechanism with said rotor being directly coupled by said shaft to said compressor mechanism inside said hermetically sealed enclosure;

temperature control means for providing a temperature signal as a function of temperature in the vicinity of the refrigeration system;

means responsive to the rotation of the rotor for deriving an electrical rotation signal from said motor; and

electronic means responsive to the rotation signal and said temperature signal for selectively energizing said windings in the at least one preselected sequence so that said rotor rotates with a variable speed, said compressor mechanism thereby providing a variable refrigerant circulation to control the temperature in the vicinity of the refrigeration system.