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

• US 5,227,704 A
• Filed: 02/27/1991
• Issued: 07/13/1993
• 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:
  US07/661,818
• Time in Patent Office: 867 Days
• Field of Search: 318/138, 318/254, 318/439, 318/599
• US Class Current: 318/400.34
• 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 6/08 Arrangements for controlling the speed or torque of a single motor H02P6/10, H02P6/28 take precedence
• 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
• CPC Class Codes: Y02B 40/00 Technologies aiming at improving the efficiency of home appliances, e.g. induction cooking or efficient technologies for refrigerators, freezers or dish washers

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 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:

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

generating a triggering signals as a function of the back emf signal to define an advancement of commutation angle alpha relative to the rotational position of the rotor of from about 5 electrical degrees to about 25 electrical degrees;

producing, in response to the triggering signal, an advanced commutation signal; and

selectively energizing the windings in a predetermined sequence in response to the commutation signal to cause advancement of commutation of the windings by the angle alpha.

2. A method as set forth in claim 1 wherein the generating step includes the step of responding only to one polarity portion of the back emf signal to integrate said one polarity portion of the back emf signal to a triggering point.

3. An electronically commutated motor controller apparatus for controlling the operational speed of an electronically commutated motor comprising controller means for selectively energizing the motor, said controller means including means or sensing back emf signals from the electronically commutated motor, means for generating a triggering signals as a function of the back emf signals to sensed, and means for producing, in response to the triggering signal, a commutation signal indicative of the rotational position of the rotor, whereby the commutation signal is repeatedly produced as the rotor turns, and the apparatus further comprises motor speed circuit means responsive to the commutation signal repeatedly produced for generating a speed signal, and means for producing a pulsating speed control signal responsive to said speed signal, said speed control signal being transmitted to said controller means for adjusting the speed of the electronically commutated motor.

4. Electronically commutated motor controller apparatus as set forth in claim 3 further comprising sensing means for sensing motor current, said sensing means connected to vary the energization of the motor depending on the motor current.

5. Electronically commutated motor controller apparatus as set forth in claim 3 wherein the motor has windings and the apparatus further comprises a capacitor connected to said controller means and unidirectional conduction means for returning to the capacitor energy released by a decaying magnetic field of a winding of the motor when it is deenergized.

6. An apparatus for 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 apparatus comprising:

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

means for generating a triggering signal as a function of the back emf signal to define an advancement of commutation angle alpha relative to the rotational position of the rotor of from about 5 electrical degrees to about 25 electrical degrees;

means for producing, in response to the triggering signal, an advanced commutation signal; and

means for selectively energizing the windings in a predetermined sequence in response to the commutation signal to cause the advancement of commutation of the windings by the angle alpha.

7. The apparatus as set forth in claim 6 wherein the means for generating includes means for responding only to one polarity portion of the back emf signal and for integrating said one polarity portion of the back emf signal to a triggering point.

8. 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 comprising the steps of:

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

generating a triggering signals as a function of the back emf signal to define an advancement of commutation angle alpha relative to the rotational position of the rotor of at least about 5 electrical degrees;

producing, in response to the triggering signal, an advanced commutation signal; and

selectively energizing the windings in a predetermined sequence in response to the commutation signal to cause advancement of commutation of the windings by the angle alpha.

9. An apparatus for 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 apparatus comprising:

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

means for generating a triggering signal as a function of the back emf signal to define an advancement of commutation angle alpha relative to the rotational position of the rotor of at least about 5 electrical degrees;

means for producing, in response to the triggering signal, an advanced commutation signal;

means for selectively energizing the windings in a predetermined sequence in response to the commutation signal to cause the advancement of commutation of the windings by the angle alpha.

10. A method of operating a brushless motor having a stationary armature with a slotted core, the slots for receiving coils of wire, and having a plurality of coils of wire received in the slots to form at least two different energizable windings for producing spaced apart magnetic fields in time sequence, said coils having a preselected distribution to provide and average torque according to the desired motor characteristics to be obtained, and further having a rotor including at least two permanent magnets adapted to rotate in response to the magnetic fields, the method comprising the steps of:

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

generating a triggering signal as a function of the back emf signal to define an advancement of commutation angle alpha relative to the rotational position of the rotor of from about 5 electrical degrees to about 25 electrical degrees;

producing, in response to the triggering signal, an advanced commutation signal; and

selectively energizing the windings in a predetermined sequence in response to the commutation signal to cause advancement of commutation of the windings by the angle alpha.

11. A method as set forth in claim 10 wherein the generating step includes the step of responding only to one polarity portion of the back emf signal to integrate said one polarity portion of the back emf signal to a triggering point.

12. A brushless motor comprising:

a stationary armature having a slotted core, the slots for receiving coils of wire;

a plurality of coils of wire received in the slots to form at least two different energizable windings for producing spaced apart magnetic fields in time sequence, said coils having a preselected distribution to provide an average torque according to the desired motor characteristics to be obtained;

a rotor including at least two permanent magnets adapted to rotate in response to the magnetic fields;

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

means for generating a triggering signal as a function of the back emf signal to define an advancement of commutation angle alpha relative to the rotational position of the rotor of from about 5 electrical degrees to about 25 electrical degrees;

means for producing, in response to the triggering signal, an advanced commutation signal; and

means for selectively energizing the windings in a predetermined sequence in response to the commutation signal to cause the advancement of commutation of the windings by the angle alpha.

13. The apparatus as set forth in claim 12 wherein the means for generating includes means for responding only to one polarity portion of the back emf signal and for integrating said one polarity portion of the back emf signal to a triggering point.

14. A method of operating a brushless motor having a stationary armature with a slotted core, the slots for receiving coils of wire, and having a plurality of coils of wire received in the slots to form at least two different energizable windings for producing spaced apart magnetic fields in time sequence, the method comprising the steps of:

providing said coils with a preselected distribution to provide an average torque according to the desired motor characteristics to be obtained, and further having a rotor including at least two permanent magnets adapted to rotate in response to the magnetic fields, the method comprising the steps of;

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

generating a triggering signal as a function of the back emf signal to define an advancement of commutation angle alpha relative to the rotational position of the rotor of at least about 5 electrical degrees;

producing, in response to the triggering signal, an advanced commutation signal; and

selectively energizing the windings in a predetermined sequence in response to the commutation signal to cause advancement of commutation of the windings by the angle alpha.

15. A brushless motor comprising:

a stationary armature having a slotted core, the slots for receiving coils of wire;

a plurality of coils of wire received in the slots to form at least two different energizable windings for producing spaced apart magnetic fields in time sequence, said coils having a preselected distribution to provide an average torque according to the desired motor characteristics to be obtained;

a rotor including at least two permanent magnets adapted to rotate in response to the magnetic fields;

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

means for generating a triggering signal as a function of the back emf signal to define an advancement of commutation angle alpha relative to the rotational position of the rotor of at least about 5 electrical degrees;

means for producing, in response to the triggering signal, an advanced commutation signal; and

means for selectively energizing the windings in a predetermined sequence in response to the commutation signal to cause the advancement of commutation of the windings by the angle alpha.