Laundering apparatus, method of operating a laundry machine, control system for an electronically commutated motor, method of operating an electronically commutated motor, and circuit

• US 4,556,827 A
• Filed: 07/21/1982
• Issued: 12/03/1985
• Est. Priority Date: 04/17/1980
• Status: Expired due to Term

• Current Assignee: General Electric Company
• Original Assignee: General Electric Company
• Inventors: Erdman, David M.
• Primary Examiner(s): Shoop, Jr., William M.
• Assistant Examiner(s): Ro, Bentsu
• Application Number:
  US06/400,214
• Time in Patent Office: 1,231 Days
• Field of Search: 318/138, 318/254, 318/439, 318/341, 318/317, 318/329, 318/330, 318/342, 318/345 R, 318/345 B, 318/318, 363/41, 363/86, 363/124, 363/42, 323/235, 323/282, 323/319, 307/240
• US Class Current: 318/400.3
• CPC Class Codes: D06F 23/04 and rotating or oscillating about a vertical axis
• CPC Class Codes: D06F 37/304 Arrangements or adaptations of electric motors
• CPC Class Codes: F25B 2600/021 Inverters therefor
• CPC Class Codes: H02P 6/085 in a bridge configuration

Abstract

A circuit for controlling the energization of an electrical load from an AC source. The circuit has a pair of DC lines, and means is provided for rectifying the AC output of the source to apply a DC voltage across the DC lines in the form of a full wave rectified sinusoidal signal. Signal switching means for connection between the DC lines and the load establishes a conductive path therebetween during a variable time interval when the voltage applied by the full wave rectified sinusoidal signal exceeds the voltage across the load, and means including the switching means is provided for chopping the full wave rectified sinusoidal signal to apply pulses to the load during the variable time interval at a frequency which is high with respect to the frequency of the signal. Means connected to the chopping means for modulating the width of the pulses is responsive to an externally derived signal representative of the desired operation of the load, and means is responsive to the load current for modifying the externally derived signal to maintain the amplitude of the load current below a predetermined level whereby a high power factor is presented to the AC source during a predetermined range of operation of the load.

A method of operating an electronically commutated motor is also disclosed.

Claims

1. A method of operating a DC motor energized from an AC source comprising the steps of:

rectifying the output of the AC source to provide a full wave rectified sinusoidal voltage;

converting the full wave rectified sinusoidal voltage into voltage pulses having a high frequency with respect to the frequency of the full wave rectified sinusoidal voltage so as to provide an effective voltage to the motor; and

limiting the voltage pulses to the time interval in each half cycle of the full wave rectified sinusoidal voltage during which the full wave rectified sinusoidal voltage exceeds the effective voltage.

2. The method as set forth in claim 1 further comprising the step of width modulating the voltage pulses to maintain a substantially constant current in the DC motor throughout the time interval in each half cycle of the full wave rectified sinusoidal voltage during which the full wave rectified sinusoidal voltage exceeds the effective voltage.

3. A method of operating an electronically commutated motor energized from an AC source and having a stationary assembly including a plurality of winding stages adapted to be selectively commutated, and rotatable means associated with the stationary assembly in selective magnetic coupling relation with the winding stages, the motor being responsive to a control circuit for controlling the current flow through a plurality of current paths each including at least one of the winding stages, the method comprising:

rectifying the AC voltage of the source to provide a full wave rectified sinusoidal voltage;

generating pulses having a high frequency with respect to the frequency of the full wave rectified sinusoidal voltage;

commutating the winding stages by applying the full wave rectified sinusoidal voltage thereto and causing the current paths to become conductive in at least one preselected sequence; and

controlling the conductivity of respective current paths as a function of the width of the pulses when the current paths are sequentially rendered conductive.

4. The method as set forth in claim 3 wherein the controlling step provides an effective voltage to the motor and the method comprises the additional step of limiting the energization of the motor to a time interval in each half cycle of the full wave rectified sinusoidal voltage when the ratio of the effective voltage to the AC source voltage has a selectively determined relationship.

5. A circuit for controlling the energization of an electrical load from an AC source, comprising:

a pair of DC lines;

means for rectifying the AC output of the source to apply a DC voltage across said DC lines in the form of a full wave rectified sinusoidal voltage;

means for chopping the full wave rectified sinusoidal voltage to apply pulses to the load at a frequency which is high with respect to the frequency of the full wave rectified sinusoidal voltage during the time interval when the full wave rectified sinusoidal voltage exceeds the voltage across the load; and

means connected to said chopping means for modulating the width of the pulses and

for thereby maintaining the amplitude of the load current below a predetermined level responsive to an externally derived signal representative of the desired operation of the load.

6. A circuit as set forth in claim 5 wherein said chopping means comprises a switching transistor connected in series between one of said DC lines and the load, said pulse width modulation means being connected to the base of said transistor.

7. A circuit for controlling the energization of an electronically commutated motor from an AC source, the motor including a stationary assembly having a plurality of winding stages associated therewith and adapted to be selectively commutated, and rotatable means associated with the stationary assembly in selective magnetic coupling relation with the winding stages, the circuit comprising:

a pair of DC lines;

means for rectifying the AC output of the source to apply a DC voltage across said DC lines in the form of a full wave rectified sinusoidal voltage;

means responsive to the angular position of the rotatable assembly for deriving commutation signals;

a plurality of current paths connected across said DC lines each including electronic commutation means for connection in series with at least one of the winding stages and responsive to the commutation signals to render said current paths conductive in sequence;

means connected to said commutation means for chopping the full wave rectified sinusoidal voltage in each of said conductive current paths so as to provide pulses in said conductive current paths having a frequency which is high with respect to the frequency of the full wave rectified sinusoidal voltage during the time interval when the full wave rectified sinusoidal voltage exceeds the voltage across the electronically commutated motor; and

means responsive to an externally derived signal representative of the desired operation of the motor for modulating the width of the pulses.

8. A circuit as set forth in claim 7 wherein the action of said commutation means produces an effective voltage and current in the winding stages as said current paths become conductive, the pulse width modulating means comprising

means responsive to the effective current in the winding stages for also modifying the externally derived signal to maintain the effective current below a predetermined level.

9. A circuit for controlling an electronically commutated motor for use with a power supply for supplying a full wave rectified sinusoidal voltage, the electronically commutated motor including a stationary assembly having a plurality of winding stages adapted to be selectively commutated, and rotatable means associated with the stationary assembly in selective magnetic coupling relation with the winding stages, the circuit comprising:

means for producing pulses of the full wave rectified sinusoidal voltage during a single continuous interval in each half cycle of the full wave rectified sinusoidal voltage and applying them to the winding stages in at least one preselected sequence thereby to commutate the winding stages and rotate the rotatable means, the voltage pulses having a frequency which is high with respect to the frequency of the full wave rectified sinusoidal voltage; and

means for width modulating the voltage pulses to produce substantially rectangular current pulses flowing in the electronically commutated motor, each of the rectangular current pulses occurring during the single continuous interval in each half cycle of the full wave rectified sinusoidal voltage.

10. The circuit as set forth in claim 9 wherein said width modulating means includes means for also adjusting the current flowing in the motor as a function of an input signal indicative of a desired angular velocity of the rotating means.

11. The circuit as set forth in claim 9 wherein said voltage pulse producing and applying means includes switching transistor means and filter means connected between said switching transistor means and the winding stages for producing the motor current at the output of said filter means.

12. The circuit as set forth in claim 9 wherein said voltage pulses producing and applying means includes means for also producing the pulses of the full wave rectified sinusoidal voltage only during a predetermined time interval in each half cycle of the full wave rectified sinusoidal voltage, the initiating and terminating points respectively of each such predetermined time interval being spaced substantially equal phase angles away from the initiating and terminating zero crossovers respectively that define the corresponding half cycle of the full wave rectified sinusoidal voltage.

13. The circuit as set forth in claim 9 wherein said voltage pulse producing and applying means comprises means for also limiting the production of the voltage pulses so that the single continuous interval in each half cycle of the full wave rectified sinusoidal voltage is the time interval during which the full wave rectified sinusoidal voltage exceeds the voltage across the motor.

14. An electronically commutated motor system comprising:

an electronically commutated motor including a stationary assembly having a plurality of winding stages associated therewith adapted to be selectively commutated, and rotatable means associated with said stationary assembly in selective magnetic coupling relation with said winding stages;

power supply means for supplying a full wave rectified sinusoidal voltage;

means for producing pulses of the full wave rectified sinusoidal voltage during a single continuous interval in each half cycle of the full wave rectified sinusoidal voltage and applying them to said winding stages in at least one preselected sequence thereby to commutate said winding stages and rotate said rotatable means, the voltage pulses having a frequency which is high with respect to the frequency of the full wave rectified sinusoidal voltage; and

means for width modulating the voltage pulses to produce substantially rectangular current pulses flowing in said electronically commutated motor, each of the rectangular current pulses occurring during the single continuous interval in each half cycle of the full wave rectified sinusoidal voltage.

15. The electronically commutated motor system as set forth in claim 14 wherein said width modulating means includes means for also adjusting the current flowing in said motor as a function of an input signal indicative of a desired angular velocity of said rotatable means.

16. The electronically commutated motor system as set forth in claim 14 wherein said voltage pulse producing and applying means includes switching transistor means and filter means connected between said switching transistor means and said winding stages for producing the motor current at the output of said filter means.

17. The electronically commutated motor system as set forth in claim 14 wherein said voltage pulse producing and applying means includes means for also producing the pulses of the full wave rectified sinusoidal voltage only during a predetermined time inverval in each half cycle of the full wave rectified sinusoidal voltage, the initiating and terminating points respectively of each such predetermined time interval being spaced substantially equal phase angles away from the initiating and terminating zero crossovers respectively that define the corresponding half cycle of the full wave rectified sinusoidal voltage.

18. The electronically commutated motor system as set forth in claim 14 wherein said voltage pulse producing and applying means comprises means for also limiting the production of the voltage pulses so that the single continuous interval in each half cycle of the full wave rectified sinusoidal voltage is the time interval during which the full wave rectified sinusoidal voltage exceeds the voltage across said motor.

19. The electronically commutated motor system as set forth in claim 14 wherein said voltage pulse producing and applying means comprises pairs of series connected electronic devices, each pair having a junction point connected to each of said winding stages respectively, said electronic devices being able to be switched on in the at least one preselected sequence, and means for switching the full wave rectified sinusoidal voltage at the high frequency across all of said pairs of series connected electronic devices in response to said width modulating means.

20. The electronically commutated motor system as set forth in claim 14 wherein said voltage pulse producing and applying means comprises oscillator means, commutation circuit means, logic gate means, and pairs of series connected electronic devices each pair having a junction point connected to each of the winding stages respectively, said electronic devices being enabled in the at least one preselected sequence by said commutation circuit means through said logic gate means, said oscillator means switching said electronic devices which are enabled through said logic gate means at the frequency which is high with respect to the full wave rectified sinusoidal voltage.

21. Laundry apparatus comprising:

means operable generally in a laundering mode for agitating fluid and fabrics to be laundered therein and operable generally in a spin mode for thereafter spinning the fabrics to effect centrifugal displacement of fluid from the fabrics;

an electronically commutated motor including a stationary assembly, a multi-stage winding arrangement associated with said stationary assembly and having a plurality of winding stages adapted to be commutated in a plurality of preselected sequences, and rotatable means rotatably associated with said stationary assembly and arranged in selective magnetic coupling relation with said winding stages for driving said agitating and spinning means in the laundering mode operation and in the spin mode operation thereof upon the commutation of said winding stages;

power supply means for supplying a full wave rectified sinusoidal voltage;

means for producing pulses of the full wave rectified sinusoidal voltage during a single continuous interval in each half cycle of the full wave rectified sinusoidal voltage, for applying them to said winding stages in one of the preselected sequences to commutate said winding stages and effect the spin mode operation of said agitating and spinning means and for applying the voltage pulses to said winding stages in both the one preselected sequence and another preselected sequence to effect the laundering mode operation of said agitating and spinning means, the voltage pulses having a frequency which is high with respect to the frequency of the full wave rectified sinusoidal voltage; and

means for width modulating the voltage pulses to produce substantially rectangular current pulses flowing in said electronically commutated motor, each of the rectangular current pulses occurring during the single continuous interval in each half cycle of the full wave rectified sinusoidal voltage.

22. The laundry apparatus as set forth in claim 21 wherein said width modulating means includes means for also adjusting the current flowing in said motor as a function of an input signal indicative of a desired angular velocity of said rotatable means.

23. The laundry apparatus as set forth in claim 21 wherein said voltage pulse producing and applying means includes switching transistor means and filter means connected between said switching transistor means and said winding stages for producing the motor current at the output of said filter means.

24. The laundry apparatus as set forth in claim 21 wherein said voltage pulse producing and applying means includes means for also producing the pulses of the full wave rectified sinusoidal voltage only during a predetermined time interval in each half cycle of the full wave rectified sinusoidal voltage.

25. The laundry apparatus as set forth in claim 21 wherein said voltage pulse producing and applying means comprises means for also limiting the production of the voltage pulses so that the single continuous interval in each half cycle of the full wave rectified sinusoidal voltage is the time interval during which the full wave rectified sinusoidal voltage exceeds the voltage across said motor.

26. The laundry apparatus as set forth in claim 21 wherein said voltage pulse producing and applying means comprises pairs of series connected electronic devices, each pair having a junction point connected to each of said winding stages respectively, said electronic devices being able to be switched on in each of the preselected sequences, and means for switching the full wave rectified sinusoidal voltage at the high frequency across all of said pairs of series connected electronic devices in response to said width modulating means.

27. The laundry apparatus as set forth in claim 21 wherein said voltage pulse producing and applying means comprises oscillator means, commutation circuit means, logic gate means, and pairs of series connected electronic devices each pair having a junction point connected to each of the winding stages respectively, said electronic devices being enabled in each of the preselected sequences by said commutation circuit means through said logic gate means, said oscillator means switching said electronic devices which are enabled through said logic gate means at the frequency which is high with respect to the full wave rectified sinusoidal voltage.

28. A method of operating a system having an electronically commutated motor including a stationary assembly having a plurality of winding stages adapted to be selectively commutated, and rotatable means associated with the stationary assembly in selective magnetic coupling relation with the winding stages, power supply means for supplying a full wave rectified sinusoidal voltage, and means for commutating the winding stages by applying a voltage thereto in at least one preselected sequence during successive commutation periods thereby to rotate the rotatable means, the method comprising the steps of:

switching the full wave rectified sinusoidal voltage at a frequency which is high with respect to the frequency of the full wave rectified sinusoidal voltage during a single continuous interval in each half cycle of the full wave rectified sinusoidal voltage thereby to produce the voltage applied by the commutating means in pulses; and

width modulating the switching to width modulate the voltage pulses and to produce substantially rectangular current pulses flowing in the electronically commutated motor, each such current pulse occurring during the single continuous interval in each half cycle of the full wave rectified sinusoidal voltage.

29. The method as set forth in claim 28 further comprising the step of enabling the switching only during a predetermined time interval in each half cycle of the full wave rectified sinusoidal voltage, the initiating and terminating points respectively of each such predetermined time interval being spaced substantially equal phase angles away from the initiating and terminating zero crossovers respectively that define the corresponding half cycle of the full wave rectified sinusoidal voltage.

30. The method as set forth in claim 28 further comprising the step of limiting the switching so that the single continuous interval in each half cycle of the full wave rectified sinusoidal signal is the time interval during which the full wave rectified sinusoidal voltage exceeds the voltage across the motor.

31. A method of operating an electronically commutated motor including a stationary assembly having a plurality of winding stages adapted to be selectively commutated, and rotatable means associated with the stationary assembly in selective magnetic coupling relation with the winding stages, the motor being responsive to a control circuit having a plurality of current paths to the winding stages, the method comprising:

rectifying an AC voltage to provide a full wave rectified sinusoidal voltage;

generating pulses having a high frequency with respect to the frequency of the full wave rectified sinusoidal voltage;

commutating the winding stages by applying a voltage thereto and causing the current paths to become conductive in at least one preselected sequence; and

switching the full wave rectified sinusoidal voltage in response to the high frequency pulses during the time interval in each half cycle of the full wave rectified sinusoidal voltage during which the full wave rectified sinusoidal voltage exceeds the voltage across the motor thereby to produce the voltage applied by the commutating means in pulses having a frequency which is high with respect to the frequency of the full wave rectified sinusoidal voltage.

32. The method as set forth in claim 31 further comprising the step of width modulating the switching to width modulate the voltage pulses and to produce substantially rectangular current pulses flowing in the electronically commutated motor, each such current pulse occupying the time interval in each half cycle of the full wave rectified sinusoidal voltage during which the full wave rectified sinusoidal voltage exceeds the voltage across the motor.

33. Laundry apparatus comprising:

means operable generally in a laundering mode for agitating fluid and fabrics to be laundered therein and operable generally in a spin mode for thereafter spinning the fabrics to effect centrifugal displacement of fluid from the fabrics;

an electronically commutated motor including a stationary assembly, a multi-stage winding arrangement associated with said stationary assembly and having a plurality of winding stages adapted to be commutated in a plurality of preselected sequences, and rotatable means rotatably associated with said stationary assembly and arranged in selective magnetic coupling relation with said winding stages for driving said agitating and spinning means in the laundering mode operation and in the spin mode operation thereof upon the commutation of said winding stages;

power supply means for supplying a full wave rectified sinusoidal voltage;

means for switching the full wave rectified sinusoidal voltage to produce voltage pulses during a single continuous interval in each half cycle of the full wave rectified sinusoidal voltage, for filtering the voltage pulses and for applying the filtered voltage pulses to at least some of said winding stages in at least one of the preselected sequences to commutate said at least some winding stages and effect the laundering mode and the spin mode operation of said agitating and spinning means, the voltage pulses having a frequency which is high with respect to the frequency of the full wave rectified sinusoidal voltage; and

means for width modulating the voltage pulses to produce substantially rectangular current pulses flowing in said electronically commutated motor, each of the rectangular current pulses occuring during the single continuous interval in each half cycle of the full wave rectified sinusoidal voltage, and for adjusting the level of the rectangular current pulses in said motor as a function of an input signal.

34. Laundry apparatus as set forth in claim 33 wherein said switching, filtering, and applying means includes a plurality of sets of electronic switching devices, each set having at least one junction point connected to a corresponding one of said at least some winding stages.

35. Laundry apparatus comprising:

means operable generally in a laundering mode for agitating fluid and fabrics to be laundered therein and operable generally in a spin mode for thereafter spinning the fabrics to effect centrifugal displacement of fluid from the fabrics;

an electronically commutated motor including a stationary assembly, a multi-stage winding arrangement associated with said stationary assembly and having a plurality of winding stages adapted to be commutated in a plurality of preselected sequences, and rotatable means rotatably associated with said stationary assembly and arranged in selective magnetic coupling relation with said winding stages for driving said agitating and spinning means in the laundering mode operation and in the spin mode operation thereof upon the commutation of said winding stages;

power supply means for supplying a full wave rectified sinusoidal voltage;

means for producing pulses of the full wave rectified sinusoidal voltage which are confined to a single continuous interval in each half cycle of the full wave rectified sinusoidal voltage during which the full wave rectified sinusoidal voltage exceeds the voltage across said motor, for applying them to at least some of said winding stages in one of the preselected sequences to commutate said at least some winding stages and effect the spin mode operation of said agitating and spinning means and for applying the voltage pulses to at least some of said winding stages in both the one preselected sequence and another preselected sequence to effect the laundering mode operation of said agitating and spinning means, the voltage pulses having a frequency which is high with respect to the frequency of the full wave rectified sinusoidal voltage; and

means for width modulating the voltage pulses to produce substantially rectangular current pulses flowing in said electronically commutated motor, each of the rectangular current pulses occurring during the single continuous interval in each half cycle of the full wave rectified sinusoidal voltage, and for adjusting the current in said motor as a function of an input signal indicative of a desired angular velocity of said rotatable means.

36. The laundry apparatus as set forth in claim 35 wherein said voltage pulse producing and applying means includes switching transistor means and filter means connected between said switching transistor means and said winding stages for producing the motor current at the output of said filter means.

37. Laundry apparatus comprising:

means operable generally in a laundering mode for agitating fluid and fabrics to be laundered therein and operable generally in a spin mode for thereafter spinning the fabrics to effect centrifugal displacement of fluid from the fabrics;

an electronically commutated motor including a stationary assembly, a multi-stage winding arrangement associated with said stationary assembly and having a plurality of winding stages adapted to be commutated in a plurality of preselected sequences, and rotatable means rotatably associated with said stationary assembly and arranged in selective magnetic coupling relation with said winding stages for driving said agitating and spinning means in the laundering mode operation and in the spin mode operation thereof upon the commutation of said winding stages;

power supply means for supplying a full wave rectified sinusoidal voltage;

a plurality of sets of electronic devices, each set having at least one junction point connected to at least some of said winding stages, respectively, said electronic devices being able to be switched on in at least some of the preselected sequences;

means for switching the full wave rectified sinusoidal voltage across all of said sets of electronic devices; and

means connected to said switching means for causing pulses of the full wave rectified sinusoidal voltage to be produced by said switching means, the voltage pulses having a frequency which is high with respect to the frequency of the full wave rectified sinusoidal voltage, and for width modulating the voltage pulses to produce substantially rectangular current pulses flowing in said electronically commutated motor, each of the rectangular current pulses occurring during a single continuous interval in each half cycle of the full wave rectified sinusoidal voltage.

38. Laundry apparatus as set forth in claim 37 wherein said voltage pulse causing and width modulating means includes oscillator means, means for sensing the current in said motor, and pulse width modulating means having inputs connected to said oscillator means and to said sensing means, and an output connected to control said switching means.

39. Laundry apparatus as set forth in claim 37 further comprising filtering means connected between said switching means and said sets of electronic devices.

40. Laundry apparatus comprising:

means operable generally in a laundering mode for agitating fluid and fabrics to be laundered therein and operable generally in a spin mode for thereafter spinning the fabrics to effect centrifugal displacement of fluid from the fabrics;

an electronically commutated motor including a stationary assembly, a multi-stage winding arrangement associated with said stationary assembly and having a plurality of winding stages adapted to be commutated in a plurality of preselected sequences, and rotatable means rotatably associated with said stationary assembly and arranged in selective magnetic coupling relation with said winding stages for driving said agitating and spinning means in the laundering mode operation and in the spin mode operation thereof upon the commutation of said winding stages;

first and second DC lines;

power supply means for supplying a full wave rectified sinusoidal voltage across said first and second DC lines;

means responsive to the angular position of said rotatable means for deriving commutation signals;

a plurality of current paths connected to at least one of said DC lines, each of said current paths including electronic commutation means for connection in series with at least one of said winding stages and responsive to the commutation signals for making said current paths conductive in one of the preselected sequences to commutate at least some of said winding stages to effect the spin mode operation of said agitating and spinning means and for making said current paths conductive in both the one preselected sequence and another preselected sequence to effect the laundering mode operation of said agitating and spinning means; and

means connected to said commutation means for chopping the full wave rectified sinusoidal voltage in each of said conductive current paths to provide voltage pulses in said conductive current paths having a frequency which is high with respect to the frequency of the full wave rectified sinusoidal voltage and for width modulating the voltage pulses to produce substantially rectangular current pulses respectively flowing in said electronically commutated motor in a single continuous interval in each of at least some of the half cycles of the full wave rectified sinusoidal voltage.

41. Laundry apparatus as set forth in claim 40 wherein at least one of said electronic commutation means includes logic gate means and a plurality of transistors connected between said at least one winding stage and at least one of said first and second DC lines, said logic gate means coupling said means for deriving commutation signals to at least one of said transistors.

42. Laundry apparatus as set forth in claim 41 wherein said chopping and width modulating means is connected to said logic gate means.

43. Laundry apparatus as set forth in claim 41 wherein said chopping and width modulating means is connected to said logic gate means to disable said logic gate means at the frequency which is high with respect to the full wave rectified sinusoidal voltage thereby causing at least one at a time of said transistors to be switched at the high frequency, said means responsive to the angular position of said rotatable means for deriving commutation signals including means for selecting in at least one of the preselected sequences each of said transistors which is to be switched at the high frequency.

44. Laundry apparatus as set forth in claim 40 wherein said chopping and width modulating means includes means for also adjusting the current flowing in said motor as a function of an input signal indicative of a desired angular velocity of said rotatable means.

45. Laundry apparatus comprising:

means operable generally in a laundering mode for agitating fluid and fabrics to be laundered therein and operable generally in a spin mode for thereafter spinning the fabrics to effect centrifugal displacement of fluid from the fabrics;

an electronically commutated motor including a stationary assembly, a multi-stage winding arrangement associated with said stationary assembly and having a plurality of winding stages adapted to be commutated in a plurality of preselected sequences, and rotatable means rotatably associated with said stationary assembly and arranged in selective magnetic coupling relation with said winding stages for driving said agitating and spinning means in the laundering mode operation and in the spin mode operation thereof upon the commutation of said winding stages;

power supply means for supplying a full wave rectified sinusoidal voltage;

means for converting the full wave rectified sinusoidal voltage into voltage pulses having a high frequency with respect to the frequency of the full wave rectified sinusoidal voltage so as to provide an effective voltage to said electronically commutated motor, the voltage pulses being confined by said converting means to a single continuous time interval in each half cycle of the full wave rectified sinusoidal voltage; and

means for width modulating the voltage pulses to maintain a substantially constant current in said electronically commutated motor throughout the single continuous time interval.

46. Laundry apparatus as set forth in claim 45 wherein said means for converting includes means for limiting the voltage pulses to a time interval in each half cycle of the full wave rectified sinusoidal voltage during which the full wave rectified sinusoidal voltage has a selectively determined relationship to the effective voltage.

47. Laundry apparatus as set forth in claim 45 wherein said width modulating means includes means for also adjusting the current flowing in said motor as a function of an input signal indicative of a desired angular velocity of said rotatable means.

48. Laundry apparatus comprising:

means operable generally in a laundering mode for agitating fluid and fabrics to be laundered therein and operable generally in a spin mode for thereafter spinning the fabrics to effect centrifugal displacement of fluid from the fabrics;

an electronically commutated motor including a stationary assembly, a multi-stage winding arrangement associated with said stationary assembly and having a plurality of winding stages adapted to be commutated in a plurality of preselected sequences, and rotatable means rotatably associated with said stationary assembly and arranged in selective magnetic coupling relation with said winding stages for driving said agitating and spinning means in the laundering mode operation and in the spin mode operation thereof upon the commutation of said winding stages;

means for rectifying an AC voltage to provide a full wave rectified sinusoidal voltage;

means for generating pulses having a high frequency with respect to the frequency of the full wave rectified sinusoidal voltage;

means for commutating said winding stages by applying a voltage thereto in at least one preselected sequence;

means for switching the full wave rectified sinusoidal voltage in response to the high frequency pulses during a single continuous interval in each half cycle of the full wave rectified sinusoidal voltage thereby to produce the voltage applied by the commutating means in pulses having a frequency which is high with respect to the frequency of the full wave rectified sinusoidal voltage; and

means for width modulating the switching to width modulate the voltage pulses and to produce a current flowing in the electronically commutated motor which is substantially rectangular pulses, each such current pulse occupying the single continuous interval in each half cycle of the full wave rectified sinusoidal voltage.

49. The laundry apparatus as set forth in claim 48 further comprising filter means connected between said switching means and said commutating means.

50. The laundry apparatus as set forth in claim 48 wherein said width modulating means includes means for also adjusting the current flowing in said electronically commutated motor as a function of an input signal indicative of a desired angular velocity of said rotating means.