Refrigeration compressor driven by a DC motor
First Claim
1. A refrigeration system comprising:
- (a) a compressor disposed in a hermetic shell, an outdoor heat exchanger, an expansion device, and an indoor heat exchanger all of which are connected in series to comprise a hermetically sealed refrigeraton circuit for conditioning the temperature of a comfort zone;
(b) a refrigeration system controller than generates a pulse-width modulated speed command signal in response to a zone temperature setpoint and the temperature of said comfort zone;
(c) a variable speed brushless DC motor coupled to said compressor and controlled in response to said pulse-width modulated speed command signal such that;
i. said motor de-energizes in response to a pulse width of said speed command signal being within a predetermined lower pulse width range,ii. said motor de-energizes in response to said pulse width of said speed command signal being within a predetermined upper pulse width range, andiii. the speed of said motor varies as a function of said pulse width when said pulse width of said speed command signal is within a predetermined intermediate range that lies between said upper and said lower range.
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Accused Products
Abstract
A variable capacity refrigeration system includes a control scheme having three interrelated closed loops. The system includes a refrigeration system controller and at least one variable speed, electronically commutated DC motor driving a compressor. In the first closed loop, the controller supplies a speed command signal to a motor drive which governs the speed of the motor driven compressor. The speed of the compressor varies the system'"'"'s capacity to condition the temperature of a comfort zone. A temperature sensor in the zone provides a temperature feedback signal to the controller to complete the first closed loop. In the second closed loop, the speed command signal from the controller is varied in response to a speed feedback signal received from a compressor drive which includes both the motor and the motor drive. The third closed loop is between the motor drive and the motor. The motor drive electronically commutates the motor as it delivers an electrical supply to the motor in response to a position feedback signal generated from within the motor. The three loops are interrelated in that the output of the controller responds to feedback from both the temperature sensor and the compressor drive, and the output of the motor drive responds to input from both the motor and the controller.
196 Citations
50 Claims
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1. A refrigeration system comprising:
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(a) a compressor disposed in a hermetic shell, an outdoor heat exchanger, an expansion device, and an indoor heat exchanger all of which are connected in series to comprise a hermetically sealed refrigeraton circuit for conditioning the temperature of a comfort zone; (b) a refrigeration system controller than generates a pulse-width modulated speed command signal in response to a zone temperature setpoint and the temperature of said comfort zone; (c) a variable speed brushless DC motor coupled to said compressor and controlled in response to said pulse-width modulated speed command signal such that; i. said motor de-energizes in response to a pulse width of said speed command signal being within a predetermined lower pulse width range, ii. said motor de-energizes in response to said pulse width of said speed command signal being within a predetermined upper pulse width range, and iii. the speed of said motor varies as a function of said pulse width when said pulse width of said speed command signal is within a predetermined intermediate range that lies between said upper and said lower range. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8)
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9. A refrigeration system comprising:
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(a) a compressor disposed in a hermetic shell, an outdoor heat exchanger, an expansion device, and an indoor heat exchanger all of which are connected in series to comprise a hermetically sealed refrigeration circuit for conditioning the temperature of a comfort zone; (b) a temperature sensor for providinng a temperature feedback signal representing the temperature of said zone; (c) means for providing a temperature setpoint signal representing a desired temperature of said zone; (d) speed sensing means for sensing the actual rotational speed of variable speed DC electric motor that drives said compressor and for providing a motor speed feedback signal which represents the motor'"'"'s actual rotational speed; (e) means for determining a desired compressor speed based upon said temperature feedback signal and said temperature setpoint signal; (f) means for generating a pulse-width modulated signal having a pulse width that varires to control the speed of said motor to minimize the difference between said desired speed and said actual speed; (g) position sensing means for sensing the rotational position of a rotor of said motor by sensing a position feedback signal generated by a de-energized winding of said motor; and (h) a motor drive that conveys an electrical supply to said motor in response to said pulse-width modulated signal and electronically commutates said motor in response to said rotor position feedback signal. - View Dependent Claims (10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21)
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22. A method of controlling a refrigeration system comprising the steps of:
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(a) sensing the temperature of a comfort zone; (b) determining a temperature error by comparing the temperature of the comfort zone to a desired zone temperature; (c) deriving a desired compressor speed as a function of the temperature error; (d) sensing an actual speed of a refrigeration compressor driven by a variable speed, brushless DC electric motor; (e) determining the rotational position of a rotor of the DC motor by sensing a position feedback signal generated by a de-energized winding of the motor; (f) electronically commutating the motor in response to the rotor'"'"'s rotational position; (g) comparing a first digital value representing the desired compressor speed to a second digital value representing the actual compressor speed, thereby deriving a digital command speed value that commands the compressor to operate at speeds of discrete finite increments; (h) storing, in a microcomputer, a third digital value representing a predetermined speed limit; (i) recognizing, should it occur, an extreme speed condition characterized by the actual speed of the motor reaching the predetermined speed limit; (j) in the absence of an extreme speed condition, changing the speed of the compressor by changing the digital command speed value in discrete finite increments; (k) if an extreme speed condition exists, attempting to correct the extreme speed condition by changing the digital command speed value in discrete increments; and (l) de-energizing the motor if the step of attempting to correct the extreme speed condition is unsuccessful. - View Dependent Claims (23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39)
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40. A refrigeration system operating under three interrelates closed loops of control comprising:
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(a) an expansion device for modulating a flow of refrigerant through a heat exchanger functioning as an evaporator; (b) an indoor heat exchanger connected in series with said expansion device and cooperating with an indoor fan for conditioning the temperature of a comfort zone; (c) an outdoor heat exchanger connected in series with said indoor heat exchanger; (d) a hermetically sealed refrigeration compression whose speed effects its capacity to compress a refrigerant that is conveyed in series flow through said indoor heat exchanger; (e) a variable speed compressor drive connected to drive said compressor at various speeds to provide various compressor capacities, said compressor drive comprising a brushless DC motor that is electrically connected to a motor drive; (f) a temperature sensor for sensing the temperature of said comfort zone; (g) means for providing a desired temperature setpoint for said comfort zone; (h) means for determining in a desired compressor speed based upon the temperature of said comfort zone and said desired temperature setpoint; (i) means for sensing the actual speed of said compressor and for generating a speed feedback signal representing the actual speed of said compressor; (j) a controller electrically connected to said compressor drive, said temperature sensor, and said means for setting a desired setpoint temperature, said controller having means for generating a pulse-width modulated speed command signal whose pulse width varies to control the speed of said motor to minimize the difference between said desired speed and said actual speed, said controller operating within a control scheme that includes a first, second, and third closed loop that interrelates said controller, said motor drive, said DC motor, and said temperature sensor, i. said first closed loop comprising;
said speed command signal generated by said controller and conveyed to said compressor drive;an electrical supply delivered to said DC motor and having a voltage and frequency that varies in response to said speed command signal, whereby the speed of said compressor varies in response to said speed command signal; a temperature conditioning effect produced by said refrigeration system and imposed on said comfort zone to modulate its temperature by way of said indoor heat exchanger cooperating with said indoor fan, said temperature conditioning effect increasing with the speed of said compressor; a zone temperature feedback signal representing the temperature of said zone and produced by said temperature sensor, said zone temperature feedback signal being conveyed back to said controller to affect said speed command signal, thereby closing said first closed loop; ii. said second closed loop comprising said speed command signal which further varies as a function of said speed feedback signal that represents the actual speed of said compressor, said speed feedback signal being produced by said compressor drive and conveyed back to said controller, thereby closing said second closed loop and iii. said third closed loop comprising said electrical supply conveyed from said motor drive to said motor in response to a rotor position feedback signal that indicates the rotational position of a rotor of said motor, said rotor position feedback signal being generated from within said motor and conveyed back to said motor drive, thereby closing said third closed loop. - View Dependent Claims (41, 42, 43, 44, 45, 46, 47, 48, 49, 50)
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Specification