Variable capacity drive circuit for linear compressor in refrigeration appliance

Abstract

A method for operating a variable capacity drive circuit (800) for a compressor (64, 100) includes: operating a four-quadrant switch (804) and a second four-quadrant switch (806) in a first state, wherein in the first state, the first four-quadrant switch (804) is closed and the second four-quadrant switch (806) is open (1202), such that the voltage experienced by the motor (808) is equal to the AC line voltage (802); and operating the first four-quadrant switch (804) and the second four-quadrant switch (806) in a second state, wherein in the second state, the first four-quadrant switch (804) is open and the second four-quadrant switch (806) is open. The four-quadrant switch (806) is closed (1204) so ​​that the voltage experienced by the motor (808) is zero; a positive trigger angle (1010) and a negative trigger angle (1012) are provided (1206); the positive trigger angle (1010) and the negative trigger angle (1012) define when the first four-quadrant switch (804) and the second four-quadrant switch (806) operate in each of the first and second states (1208); the positive trigger angle (1010) and the negative trigger angle (1012) are used to switch between the first and second states at a switching frequency determined by the AC line voltage frequency (1210).

Description

Technical Field

[0001] The present invention relates generally to linear compressors, and more specifically to a variable capacity drive circuit for supplying power to a linear compressor in a refrigeration appliance. Background Technology

[0002] Typically, refrigeration appliances include a housing that defines one or more refrigerated compartments, such as a food preservation compartment for receiving food for storage and / or a freezer compartment for receiving food for freezing and storage. Some refrigeration appliances may also include a sealing system for cooling such refrigerated compartments. The sealing system typically includes a compressor that generates compressed refrigerant during its operation. The compressed refrigerant flows to an evaporator, where heat exchange between the refrigerated compartment and the refrigerant is used to cool the refrigerated compartment and the food located therein.

[0003] Recently, some refrigeration appliances include linear compressors for compressing refrigerants. A linear compressor typically includes a piston located within a housing and a drive coil that generates force to move the piston back and forth within the housing. During this movement, the piston compresses the refrigerant. Furthermore, linear compressors are typically operated by single-phase variable frequency drives (VFDs). A VFD is a motor drive used to control the speed and force of a motor by changing the frequency and amplitude of the motor voltage input. Single-phase VFDs typically use inverters with front-end rectifiers. However, H-bridge inverters and front-end rectifiers are complex and expensive systems that can have high switching losses.

[0004] Therefore, a linear compressor that solves the above-mentioned problems would be useful. Accordingly, the present invention relates to a linear compressor having a selectable converter design that modulates the amplitude of the excitation voltage applied to the motor. Summary of the Invention

[0005] Various aspects and advantages of the present invention will be set forth in the description which follows, or will be apparent from the description, or may be learned by practicing the invention.

[0006] In one aspect, a method is provided for operating a variable capacity drive circuit for a compressor. The variable capacity drive includes a first four-quadrant switch, a second four-quadrant switch, and a motor. The method includes: operating the first and second four-quadrant switches in a first state, in which the first four-quadrant switch is closed and the second four-quadrant switch is open. Thus, in the first state, the voltage experienced by the motor is equal to the alternating current (AC) line voltage. The method further includes: operating the first and second four-quadrant switches in a second state, in which the first four-quadrant switch is open and the second four-quadrant switch is closed. Thus, in the second state, the voltage experienced by the motor is zero. The method further includes: providing a positive trigger angle and a negative trigger angle. The positive and negative trigger angles define when the first and second four-quadrant switches operate in each of the first and second states. The method includes: using the positive and negative trigger angles to switch between the first and second states at a switching frequency determined by the AC line voltage frequency, in order to control the percentage of voltage applied to the compressor during the positive and negative half-cycles.

[0007] On the other hand, a linear compressor is provided. The linear compressor includes: a housing defining a piston and a cylinder; a motor for driving the piston and cylinder; and a variable capacity drive circuit for driving the motor. The variable capacity drive circuit includes a plurality of four-quadrant switches arranged in a totem-pole configuration between the AC line voltage of the linear compressor and the motor. The four-quadrant switches include at least a first four-quadrant switch and a second four-quadrant switch. The variable capacity drive circuit includes operating the first and second four-quadrant switches in a first state and a second state. Further, the variable capacity drive circuit includes a first state in which the first four-quadrant switch is closed and the second four-quadrant switch is open, such that the voltage experienced by the motor is equal to the AC line voltage. The variable capacity drive circuit also includes a second state in which the first four-quadrant switch is open and the second four-quadrant switch is closed, such that the voltage experienced by the motor is zero. The variable capacity drive circuit also includes a controller communicatively coupled to each of the four-quadrant switches. The controller is configured to perform multiple operations. For example, multiple operations may include, but are not limited to: providing positive and negative trigger angles that define when the first four-quadrant switch and the second four-quadrant switch are disconnected in each of the first and second states; and using the positive and negative trigger angles to switch between the first and second states at a switching frequency determined by the AC line voltage frequency in order to control the percentage of voltage applied to the compressor during the positive and negative half-cycles.

[0008] On the other hand, a refrigeration appliance is provided. The refrigeration appliance includes a housing having at least one chamber for receiving food. Further, the refrigeration appliance includes: a door allowing access to the chamber; and a linear compressor for auxiliary cooling of the chamber. The linear compressor includes: a housing defining a piston and a cylinder; a motor for driving the piston and cylinder; and a variable capacity drive circuit for driving the motor. The variable capacity drive circuit includes a plurality of four-quadrant switches arranged in a totem-pole configuration between the AC line voltage of the linear compressor and the motor. The four-quadrant switches include at least a first four-quadrant switch and a second four-quadrant switch. The variable capacity drive circuit includes operating the first and second four-quadrant switches in a first state and a second state. The variable capacity drive circuit also includes operating the first and second four-quadrant switches in the first state, in which the first four-quadrant switch is closed and the second four-quadrant switch is open, such that the voltage experienced by the motor is equal to the AC line voltage. The variable capacity drive circuit includes operating a first four-quadrant switch and a second four-quadrant switch in a second state, in which the first four-quadrant switch is open and the second four-quadrant switch is closed, such that the voltage experienced by the motor is zero. The variable capacity drive circuit also includes a controller communicatively coupled to the plurality of four-quadrant switches. The controller is configured to perform a plurality of operations, including, but not limited to: providing positive and negative firing angles that define when the first and second four-quadrant switches operate in each of the first and second states; and using the positive and negative firing angles to switch between the first and second states at a switching frequency determined by the AC line frequency, in order to control the percentage of voltage applied to the compressor during the positive and negative half-cycles.

[0009] These and other features, aspects, and advantages of the invention will become more readily understood with reference to the following description and the appended claims. Embodiments of the invention are illustrated in conjunction with the accompanying drawings, which are incorporated in and form a part of this specification, and together with the description serve to explain the principles of the invention. Attached Figure Description

[0010] Referring to the accompanying drawings, the specification sets forth a complete disclosure of the invention for those skilled in the art, which enables them to implement the invention, including the preferred embodiments thereof.

[0011] Figure 1 This is a front perspective view of a refrigeration appliance according to an exemplary embodiment of the present invention.

[0012] Figure 2 yes Figure 1 A schematic diagram of certain components of an exemplary refrigeration appliance.

[0013] Figure 3 This is a perspective sectional view of a linear compressor according to an exemplary embodiment of the present invention.

[0014] Figure 4 It is according to an embodiment of the present invention. Figure 3 Another perspective sectional view of an exemplary linear compressor.

[0015] Figure 5 This is a perspective view of a linear compressor according to an exemplary embodiment of the present invention, wherein the compressor housing has been removed for clarity.

[0016] Figure 6 It is according to an embodiment of the present invention. Figure 3 A cross-sectional view of an exemplary linear compressor, wherein the piston is in the extended position.

[0017] Figure 7 It is according to an embodiment of the present invention. Figure 3 A cross-sectional view of an exemplary linear compressor, wherein the piston is in the retracted position.

[0018] Figure 8 A block diagram of one embodiment of a controller for a refrigeration appliance according to an exemplary embodiment of the present invention is provided.

[0019] Figure 9 A schematic diagram of a method for operating a variable capacity drive circuit for a compressor according to an exemplary embodiment of the present invention is provided.

[0020] Figure 10 This is a schematic diagram of an exemplary linear compressor drive circuit according to an embodiment of the present invention.

[0021] Figure 11a This is a schematic diagram of one embodiment of a four-quadrant switch configuration according to an embodiment of the present invention.

[0022] Figure 11b This is a schematic diagram of another embodiment of the four-quadrant switch configuration according to an embodiment of the present invention.

[0023] Figure 11c This is a schematic diagram of yet another embodiment of a four-quadrant switch configuration according to an embodiment of the present invention.

[0024] Figure 12a A graph illustrating the application of the firing angle for switching between a first state and a second state according to an embodiment of the present invention is provided.

[0025] Figure 12b A graph illustrating another application of the firing angle for switching a variable capacity drive circuit between a first state and a second state, according to an embodiment of the present invention, is provided.

[0026] Figure 12c A graph illustrating yet another application of the angle by which a variable capacity drive circuit transitions between a first state and a second state, according to an embodiment of the present invention, is shown.

[0027] Figure 12d A graph illustrating another application of the angle by which a variable capacity drive circuit transitions between a first state and a second state, according to an embodiment of the present invention, is shown.

[0028] The repeated use of reference numerals in this specification and the accompanying drawings is intended to indicate the same or similar features or elements of the invention. Detailed Implementation

[0029] Referring now to embodiments of the invention, one or more examples of which are illustrated in the accompanying drawings. Each example is given by way of explanation and does not constitute a limitation thereof. Indeed, it will be apparent to those skilled in the art that various modifications and variations can be made to the invention without departing from its scope or spirit. For example, features shown or described as part of one embodiment can be used in another embodiment, thereby producing yet another embodiment. Therefore, it is desired that the invention cover such modifications and variations falling within the scope of the appended claims and their equivalents.

[0030] Now refer to the attached diagram, Figure 1 Describes the integration of a hermetically sealed refrigeration system 60 ( Figure 2 10. Refrigeration appliance. It should be understood that the term "refrigeration appliance" is generally used herein to include refrigeration appliances of any kind, such as freezers, refrigerator / freezer combinations, and conventional refrigerators of any style or model. Furthermore, it should be understood that the invention is not limited to use in electrical appliances. Therefore, the invention can be used for any other suitable purpose, such as vapor compression in an air conditioning unit or air compression in an air compressor.

[0031] exist Figure 1 In the illustrated exemplary embodiment, the refrigeration appliance 10 is described as an upright refrigerator having at least one casing or cabinet 12 defining a plurality of internal cooling storage compartments. Specifically, the refrigeration appliance 10 includes an upper food preservation compartment 14 with a door 16 and a lower freezer compartment 18 with an upper drawer 20 and a lower drawer 22. Further, as shown, the upper drawer 20 and the lower drawer 22 are "pull-out" drawers because they can be manually moved in and out of the lower freezer compartment 18 via a suitable sliding mechanism.

[0032] Now refer to Figure 2The diagram illustrates schematic representations of certain components of a refrigeration appliance 10, including its hermetically sealed refrigeration system 60. The mechanical compartment 62 contains components for performing a known vapor compression cycle for compressed air. These components include a compressor 64, a condenser 66, an expander 68, and an evaporator 70, connected in series and filled with refrigerant. As those skilled in the art will understand, the refrigeration system 60 may include additional components, such as at least one additional evaporator, compressor, expander, and / or condenser. As an example, the refrigeration system 60 may include two evaporators.

[0033] Within the refrigeration system 60, refrigerant flows into a compressor 64 to increase the pressure of the refrigerant. The compression of the refrigerant causes its temperature to rise, and this increased temperature is lowered by passing the refrigerant through a condenser 66. Within the condenser 66, the refrigerant is cooled by heat exchange with the surrounding air. As illustrated by arrow AC, a fan 72 is used to draw air through the condenser 66 to provide forced convection, enabling faster and more efficient heat exchange between the refrigerant within the condenser 66 and the surrounding air. Thus, as those skilled in the art will know, increasing the airflow through the condenser 66 can, for example, improve the efficiency of the condenser 66 by enhancing the cooling of the refrigerant contained therein.

[0034] An expansion device 68 (e.g., a valve, capillary tube, or other limiting device) receives refrigerant from the condenser 66. The refrigerant enters the evaporator 70 from the expansion device 68. As it leaves the expansion device 68 and enters the evaporator 70, the refrigerant pressure decreases. Due to the pressure drop and / or phase change of the refrigerant, the evaporator 70 is cold relative to the upper food preservation compartment 14 and the lower freezer compartment 18 of the refrigeration appliance 10. Therefore, cooling air can be generated and used to cool the upper food preservation compartment 14 and the lower freezer compartment 18 of the refrigeration appliance 10. Thus, the evaporator 70 is a heat exchanger that transfers heat from the air passing through the evaporator 70 to the refrigerant flowing through it.

[0035] In general, the vapor compression cycle components, associated fans, and associated compartments in the refrigeration circuit are sometimes referred to as a hermetically sealed refrigeration system, which is used to force cold air through the upper food preservation compartment 14 and the lower freezer compartment 18. Figure 1 ). Figure 2 The refrigeration system 60 described herein is provided by way of example only. Therefore, other configurations using the refrigeration system are also within the scope of this invention.

[0036] Now, the overall reference Figures 3 to 7 A linear compressor 100 according to an exemplary embodiment of the present invention is described. Specifically, Figure 3 and Figure 4 A three-dimensional sectional view of the linear compressor 100 is provided. Figure 5A perspective view of the linear compressor 100 is provided, with the compressor housing or casing 102 removed for clarity. Figure 6 and Figure 7 Cross-sectional views of the linear compressor with the piston in the extended and retracted positions are provided. It should be understood that the linear compressor 100 is used herein only as an exemplary embodiment to facilitate the description of various aspects of the invention. Modifications and variations of the linear compressor 100 can be made while remaining within the scope of the invention.

[0037] For example Figure 3 and Figure 4 For example, housing 102 may include a lower or lower housing 104 and an upper or upper housing 106, which are joined together to form a generally enclosed cavity 108 for housing various components of the linear compressor 100. Specifically, for example, cavity 108 may be a hermetically sealed or airtight housing that can house the working parts of the linear compressor 100 and prevent or inhibit refrigerant leakage or escape from the refrigeration system 60. Additionally, the linear compressor 100 generally defines an axial direction A, a radial direction R, and a circumferential direction C. It should be understood that the linear compressor 100 is described herein only and is illustrated to describe various aspects of the invention. Changes and modifications to the linear compressor 100 can be made while remaining within the scope of the invention.

[0038] Special reference Figures 3 to 7 This section will describe various parts and operating components of a linear compressor 100 according to an exemplary embodiment. As shown, the linear compressor 100 includes a housing 110 that extends, for example, between a first end 112 and a second end 114 along an axial direction A. The housing 110 includes a cylinder 117 defining a chamber 118. The cylinder 117 is disposed at or adjacent to the first end 112 of the housing 110. The chamber 118 extends longitudinally along the axial direction A. As discussed in more detail below, the linear compressor 100 can be used to increase the fluid pressure within the chamber 118 of the linear compressor 100. Further, the linear compressor 100 can be used to compress any suitable fluid, such as a refrigerant or air. In particular, the linear compressor 100 can be used in refrigeration appliances, such as compressor 64 (…). Figure 2 10 ( ) refrigeration appliances Figure 1 ).

[0039] Furthermore, as shown in the figure, the linear compressor 100 includes a motor 808 mounted or fixed to the housing 110. Figure 8The stator 120 of the linear compressor 100. For example, the stator 120 typically includes an outer back iron 122 extending circumferentially C within a housing 110 and a drive coil 124. The linear compressor 100 also includes one or more valves that allow refrigerant to enter and exit the chamber 118 during operation of the linear compressor 100. For example, an exhaust muffler 126 is provided at one end of the chamber 118 to regulate the flow rate of refrigerant exiting the chamber 118, while an intake valve 128 (for clarity, only shown in the image) is used. Figures 6 to 7 (As shown in the figure) is used to regulate the flow rate of refrigerant into chamber 118.

[0040] A piston 130, having a piston head 132, is slidably received within a chamber 118 of a cylinder 117. Specifically, the piston 130 is slidable along an axial direction A. During the sliding of the piston head 132 within the chamber 118, the piston head 132 compresses the refrigerant within the chamber 118. As an example, the piston head 132 can be positioned from the top dead center position (see, for example...) Figure 6 ) Along axis A toward the bottom dead center position (see example) Figure 7 The piston head 132 slides within chamber 118, which is the expansion stroke of the piston head 132. When the piston head 132 reaches the bottom dead center position, it changes direction and slides back towards the top dead center position within chamber 118, which is the compression stroke of the piston head 132. It should be understood that the linear compressor 100 may include additional piston heads and / or additional chambers at opposite ends of the linear compressor 100. Thus, in an optional exemplary embodiment, the linear compressor 100 may have multiple piston heads.

[0041] As shown, the linear compressor 100 also includes a mover 140, typically driven by a stator 120, for compressing the refrigerant. Specifically, for example, the mover 140 may include an inner back iron 142 disposed within the stator 120 of the motor 808. In particular, the outer back iron 122 and / or drive coil 124 may extend, for example, around the inner back iron 142 along a circumferential direction C. The inner back iron 142 also has an outer surface facing the outer back iron 122 and / or drive coil 124. At least one drive magnet 144 is mounted to the inner back iron 142, for example, mounted on the outer surface of the inner back iron 142.

[0042] The drive magnet 144 may face and / or be exposed to the drive coil 124. Specifically, the drive magnet 144 may be spaced apart from the drive coil 124 by an air gap, for example, along a radial direction R. This defines an air gap between the opposing surfaces of the drive magnet 144 and the drive coil 124. The drive magnet 144 may also be mounted or secured to the inner back iron 142 such that the outer surface of the drive magnet 144 is substantially flush with the outer surface of the inner back iron 142. This allows the drive magnet 144 to be inserted within the inner back iron 142. Thus, during operation of the linear compressor 100, the magnetic field from the drive coil 124 may only need to pass through a single air gap between the outer back iron 122 and the inner back iron 142, and the linear compressor 100 may be more efficient than a linear compressor with air gaps on both sides of the drive magnet 144.

[0043] As in Figure 3 As can be seen, the drive coil 124 extends, for example, circumferentially C, around the inner back iron 142. In other exemplary embodiments, the inner back iron 142 may extend circumferentially C around the drive coil 124. During operation of the drive coil 124, the drive coil 124 is used to drive the inner back iron 142 to move along the axial direction A. As an example, as will be understood by those skilled in the art as described above, a current can be induced in the drive coil 124 by a current source (not shown) to generate a magnetic field that attracts the drive magnet 144 and pushes the piston 130 to move along the axial direction A, thereby compressing the refrigerant in the chamber 118. In particular, during operation of the drive coil 124, the magnetic field of the drive coil 124 may attract the drive magnet 144 to move the inner back iron 142 and the piston head 132 along the axial direction A. Thus, during operation of the drive coil 124, the drive coil 124 may cause the piston 130 to slide between the top dead center position and the bottom dead center position, for example, by moving the inner back iron 142 along the axial direction A.

[0044] Special reference Figure 8 The operation of the refrigeration appliance 10 can typically be controlled by a processing device or controller 1176. Controller 1176 may, for example, be operatively coupled to control panel 24 for user manipulation to select features and operations of the refrigeration appliance 10, such as a temperature setpoint. Thus, controller 1176 can operate various components of the refrigeration appliance 10 to perform selected system cycles, processes, and / or features. In an exemplary embodiment, controller 1176 is operatively communicated (e.g., electrically or wirelessly) with various chambers or compartments therein, for example, for regulating temperature, as described herein.

[0045] More specifically, such as Figure 8The diagram illustrates a block diagram of one embodiment of suitable components that may be included within a controller 1176 according to an exemplary aspect of the invention. As shown, the controller 1176 may include one or more processors 1178, a computer or other suitable processing unit, and associated storage devices 1180, which may include suitable computer-readable instructions that, when executed, configure the controller to perform various functions, such as receiving, sending, and / or executing signals (e.g., performing the methods, steps, calculations, etc. disclosed herein).

[0046] As used herein, the term "processor" refers not only to integrated circuits known in the art as included in a computer, but also to controllers, microcontrollers, microcomputers, programmable logic controllers (PLCs), application-specific integrated circuits (ASICs), and other programmable circuits. Additionally, storage device 1180 may generally include storage elements, including but not limited to computer-readable media (e.g., random access memory (RAM)), computer-readable non-volatile media (e.g., flash memory), floppy disks, optical disc read-only memory (CD-ROM), magneto-optical disc (MOD), digital versatile optical disc (DVD), and / or other suitable storage elements. The memory may be a component separate from the processor or may be included on a board within the processor.

[0047] Such storage device 1180 can typically be configured to store suitable computer-readable instructions that, when implemented by processor 1178, configure the controller to perform various functions as described herein. Specifically, processor 1178 may include a microprocessor, CPU, or similar general-purpose or special-purpose microprocessor operable to execute programming instructions or microcontroller code related to the operation of linear compressor 100. Additionally, controller 1176 may include a communication module 1182 to facilitate communication between the controller and various components of refrigeration appliance 10. Interfaces may include one or more circuits, terminals, pins, contacts, conductors, or other components for sending and receiving control signals. Furthermore, controller 1176 may include a sensor interface 1184 (e.g., one or more analog-to-digital converters) to allow signals transmitted from temperature probe 1214 to be converted into signals that can be understood and processed by processor 1178. Furthermore, controller 1176 may optionally receive a second temperature signal from thermistor 1216, which is configured to generate one or more second temperature signals representing the actual temperature of the article or chamber.

[0048] Alternatively, the controller 1176 can be constructed to perform control functions without using a microprocessor, for example, using a combination of discrete analog and / or digital logic circuits (such as switches, amplifiers, integrators, comparators, flip-flops, AND gates, etc.), rather than relying on software.

[0049] The inner backplate 142 also includes an outer cylinder 146 and an inner sleeve 148. The outer cylinder 146 defines the outer surface of the inner backplate 142 and also has an inner surface disposed opposite to the outer surface of the outer cylinder 146. The inner sleeve 148 is disposed on or at the inner surface of the outer cylinder 146. A first interference fit between the outer cylinder 146 and the inner sleeve 148 can connect or fix the outer cylinder 146 and the inner sleeve 148 together. In an alternative exemplary embodiment, the inner sleeve 148 may be welded, glued, fastened or attached to the outer cylinder 146 via any other suitable mechanism or method.

[0050] The outer cylinder 146 can be constructed from or using any suitable material. For example, the outer cylinder 146 can be constructed from or using multiple (e.g., ferromagnetic) laminations. The laminations are distributed along a circumferential direction C to form the outer cylinder 146 and are mounted or fixed together with each other, for example, by pressing the ends of the laminations together with rings. The outer cylinder 146 may define a recess that extends inward from the outer surface of the outer cylinder 146, for example, along a radial direction R. A drive magnet 144 is disposed in the recess on the outer cylinder 146, for example, such that the drive magnet 144 is embedded within the outer cylinder 146.

[0051] The linear compressor 100 also includes a pair of flat springs 150. Each flat spring 150 can be connected, for example, along the axial direction A to a corresponding end of the inner back iron 142. During operation of the drive coil 124, the flat springs 150 support the inner back iron 142. Specifically, the inner back iron 142 is suspended by the flat springs 150 within the stator or motor 808 of the linear compressor 100, such that movement of the inner back iron 142 along the radial direction R is prevented or restricted, while movement along the axial direction A is relatively unimpeded. Thus, the stiffness of the flat springs 150 along the radial direction R can be greater than that along the axial direction A. In this way, during operation of the motor 808 and movement of the inner back iron 142 along the axial direction A, the flat springs 150 can, for example, help maintain the uniformity of the air gap between the drive magnet 144 and the drive coil 124 along the radial direction R. The flat springs 150 can also help prevent the lateral pull of the motor 808 from being transmitted to the piston 130 and reacting as frictional loss in the cylinder 117.

[0052] A flexible mount 160 is mounted to and extends through the inner backplate 142. Specifically, the flexible mount 160 is mounted to the inner backplate 142 via an inner sleeve 148. Thus, the flexible mount 160 can be coupled (e.g., threaded) to the inner sleeve 148 at an intermediate portion to mount or secure the flexible mount 160 to the inner sleeve 148. The flexible mount 160 may facilitate the formation of a coupling 162. The coupling 162 connects the inner backplate 142 and the piston 130, such that movement of the inner backplate 142 is transmitted, for example, along axial direction A, to the piston 130.

[0053] Coupling 162 can be a compliant or flexible compliant coupling along the radial direction R. In particular, coupling 162 can be fully compliant along the radial direction R, such that the movement of the inner back iron 142 transmitted radially R to the piston 130 through coupling 162 is minimal or nonexistent. In this way, the lateral pull of the motor 808 is separated from the piston 130 and / or cylinder 117, and the friction between the piston 130 and cylinder 117 can be reduced.

[0054] As can be seen in the figure, the piston head 132 of the piston 130 has a cylindrical sidewall 170. This cylindrical sidewall 170 can extend along the axial direction A from the piston head 132 toward the inner back iron 142. The outer surface of the cylindrical sidewall 170 can slide on the cylinder 117 in the chamber 118, and the inner surface of the cylindrical sidewall 170 can be disposed opposite to the outer surface of the cylindrical sidewall 170. Thus, the outer surface of the cylindrical sidewall 170 can be radially opposite to the center of the cylindrical sidewall 170, while the inner surface of the cylindrical sidewall 170 can be radially facing the center of the cylindrical sidewall 170.

[0055] The flexible mount 160 extends, for example, along axial direction A between a first end 172 and a second end 174. According to an exemplary embodiment, the inner surface of the cylindrical sidewall 170 defines a ball seat 176 near the first end. Additionally, the coupling 162 includes a ball head 178. Specifically, for example, the ball head 178 is disposed at the first end 172 of the flexible mount 160, and the ball head 178 can contact the flexible mount 160 at the first end 172. Additionally, the ball head 178 can contact the piston 130 at the ball seat 176 of the piston 130. In particular, the ball head 178 can rest on the ball seat 176 of the piston 130, such that the ball head 178 can slide and / or rotate on the ball seat 176 of the piston 130. For example, the ball head 178 may have a truncated spherical surface disposed immediately abutting the ball seat 176 of the piston 130, the shape of which may be complementary to the truncated spherical surface of the ball head 178. The truncated spherical surface of the ball head 178 can slide and / or rotate on the ball seat 176 of the piston 130.

[0056] For example, compared to a fixed connection between the flexible mount 160 and the piston 130, the relative movement between the flexible mount 160 and the piston 130 at the interface between the ball head 178 and the ball seat 176 of the piston 130 can reduce the friction between the piston 130 and the cylinder 117. For example, when the axis of the piston 130 sliding within the cylinder 117 is angled relative to the axis of the reciprocating motion of the inner back iron 142, the truncated spherical surface of the ball head 178 can slide on the ball seat 176 of the piston 130, which, relative to the rigid connection between the inner back iron 142 and the piston 130, can reduce the friction between the piston 130 and the cylinder 117.

[0057] Further, as shown in the figure, the flexible mount 160 is connected to the inner back iron 142 at its first end 172, away from the flexible mount 160. For example, the flexible mount 160 may be connected to the inner back iron 142 at its second end 174 or between the first and second ends of the flexible mount 160. Conversely, the flexible mount 160 is disposed at or within the piston 130 at its first end 172, as discussed in more detail below.

[0058] Additionally, the flexible mount 160 includes a tubular wall 190 between the inner back iron 142 and the piston 130. A channel 192 within the tubular wall 190 is used to pass a compressible fluid, such as refrigerant or air, through the flexible mount 160 and direct it towards the piston head 132 and / or into the piston 130. The inner back iron 142 may be mounted to the flexible mount 160, for example, at a midpoint between a first end 172 and a second end 174, such that the inner back iron 142 extends around the tubular wall 190. The channel 192 may extend within the tubular wall 190 between the first end 172 and the second end 174 of the flexible mount 160, such that compressible fluid can flow through the channel 192 from the first end 172 to the second end 174 of the flexible mount 160. Thus, during operation of the linear compressor 100, the compressible fluid can flow through the inner back iron 142 within the flexible mounting 160. A silencer 194 can be disposed within a channel 192 within the tubular wall 190, for example, to reduce noise from the compressible fluid flowing through the channel 192.

[0059] The piston head 132 also defines at least one opening 196. The opening 196 of the piston head 132 extends through the piston head 132, for example, along the axial direction A. Thus, during operation of the linear compressor 100, the flow of fluid can pass through the piston head 132 via the opening 196 of the piston head to reach the chamber 118. In this way, the fluid (compressed by the piston head 132 within the chamber 118) can flow through the passage 192, passing through the flexible mount 160 and the inner back iron 142, to reach the piston 130. As described above, the suction valve 128 ( Figures 6 to 7 It can be set on piston head 132 to regulate the flow rate of compressible fluid through opening 196 into chamber 118.

[0060] Still refer to Figures 3 to 7The linear compressor 100 may also include a lubrication system 200 for circulating a lubricant (e.g., oil) through the working or moving parts of the linear compressor 100 to reduce friction, improve efficiency, etc. For example, as shown, the housing 102 may generally define a reservoir 202 for collecting oil. Specifically, the reservoir 202 may be defined in the bottom of the lower housing 104. The lubrication system 200 also includes a pump 206 for continuously circulating oil through the parts of the linear compressor 100 that require lubrication.

[0061] As shown, the linear compressor 100 may include a suction port 220 for receiving a refrigerant flow. Specifically, as shown, the suction port 220 may be defined on the housing 102 (e.g., on the lower housing 104) and configured to receive a refrigerant supply conduit to supply refrigerant to the chamber 108. As described above, the flexible mount 160 includes a tubular wall 190 defining a passage 192 for guiding a compressible fluid, such as refrigerant gas, through the flexible mount 160 toward the piston head 132. Thus, the ideal flow path for the refrigerant gas is through the suction port 220, through the passage 192, through the opening 196, and into the chamber 118. The suction valve 128 may block the opening 196 during the compression stroke, and the discharge valve 116 may allow the compressed gas to exit the chamber 118 when the desired pressure is reached.

[0062] Now refer to Figure 9 A flowchart of one embodiment of a method 1200 for operating a compressor of a refrigeration appliance is provided. Generally, method 1200 is referred to herein with reference to... Figures 1 to 7 The refrigeration appliance 10 and component 100 are described herein. However, it should be understood that the disclosed method 1200 can be implemented using any other suitable refrigeration appliance with any other suitable configuration. Additionally, although... Figure 9 The steps are described in a specific order for illustrative and discussion purposes, but the methods discussed herein are not limited to any particular order or arrangement. Those skilled in the art will understand, using the disclosure provided herein, that the various steps of the methods disclosed herein can be omitted, rearranged, combined, and / or modified in various ways without departing from the scope of the invention.

[0063] As shown in (1202), method 1200 includes: operating a first four-quadrant switch and a second four-quadrant switch in a first state, in which the first four-quadrant switch is closed and the second four-quadrant switch is open, such that the voltage experienced by the motor is equal to the AC line voltage.

[0064] As shown in (1204), method 1220 includes: operating a first four-quadrant switch and a second four-quadrant switch in a second state, in which the first four-quadrant switch is open and the second four-quadrant switch is closed, such that the voltage experienced by the motor is zero.

[0065] Still refer to Figure 9 As shown in (1206), method 1200 includes: providing a positive trigger angle and a negative trigger angle. As shown in (1208), method 1200 includes: defining when a first four-quadrant switch and a second four-quadrant switch operate in each of a first state and a second state based on the positive trigger angle and the negative trigger angle. As shown in (1210), method 1200 includes: using the positive trigger angle and the negative trigger angle to switch between a first state and a second state at a switching frequency determined by the AC line voltage frequency. As shown in (1212), method 1200 includes: controlling the percentage of voltage applied to the compressor during the positive half-cycle and the negative half-cycle based on the transition between the first state and the second state.

[0066] Figure 9 Method 1200 can be about Figure 10 , Figures 11a to 1 1d and Figures 12a to 12d To better understand, the linear compressor 100 may further include features for controlling the voltage applied to the linear compressor 100. Specifically, according to an exemplary embodiment, the linear compressor 100 may be driven by a variable capacity drive circuit 800 for controlling the voltage applied to the stator 120. While an exemplary drive circuit 800 has been described herein, it should be understood that changes and modifications can be made to the variable capacity drive circuit 800 while remaining within the scope of the invention.

[0067] According to the exemplified implementation, such as Figure 10 As shown, the variable capacity drive circuit 800 includes a plurality of four-quadrant switches (e.g., a first four-quadrant switch 804 and a second four-quadrant switch 806) arranged in a totem-pole configuration between the AC line voltage 802 of the linear compressor and the motor 808. For the purpose of explaining various aspects of the invention, the variable capacity drive circuit 800 is described below for use with the stator 120 of the linear compressor 100. However, it should be understood that various aspects of the variable capacity drive circuit 800 can be used in other compressors while remaining within the scope of this invention.

[0068] Typically, a variable capacity drive circuit 800 (e.g., in a refrigeration appliance) includes at least a first four-quadrant switch 804 and a second four-quadrant switch 806. Further, as... Figure 11a , Figure 11b and Figure 11c As specifically shown, the four-quadrant switch can have any suitable configuration. In one example, such as Figure 11a As shown, four diodes (e.g., first diode 910, second diode 912, third diode 914, and fourth diode 916) can be used to connect transistor 918 in either direction as appropriate to guide current in either direction. Furthermore, when transistor 918 is turned off, the switching network can block voltage of either polarity.

[0069] In another example, such as Figure 11b As shown, a first bidirectional voltage switch 902 and a second bidirectional voltage switch 904 are used. In this embodiment, the first bidirectional voltage switch 902 and the second bidirectional voltage switch 904 are bi-quadrant and can be placed in parallel, allowing either switch to block voltage of either polarity. Furthermore, the first bidirectional voltage switch 902 can conduct negative current, while the second bidirectional voltage switch 904 can conduct positive current. Thus, the combination of the first bidirectional voltage switch 902 and the second bidirectional voltage switch 904 can conduct current of any polarity.

[0070] In yet another example, such as Figure 11c As shown, a first bidirectional current switch 906 and a second bidirectional current switch 908 are used. The first bidirectional current switch 906 and the second bidirectional current switch 908 can be connected in series, allowing them to conduct currents of both polarities. Furthermore, the first bidirectional current switch 906 can only block negative voltages, while the second bidirectional current switch 908 can only block positive voltages. Therefore, by connecting the first bidirectional current switch 906 and the second bidirectional current switch 908 in series, voltages of both polarities can be blocked.

[0071] Furthermore, the four-quadrant switches 804 and 806 described herein can operate in multiple states. For example, in one embodiment, the first four-quadrant switch 804 and the second four-quadrant switch 806 can be open and closed in different combinations. More specifically, according to an exemplary embodiment, the variable capacity drive circuit 800 operates the first four-quadrant switch 804 and the second four-quadrant switch 806 in a first state, in which the first four-quadrant switch 804 is closed and the second four-quadrant switch 806 is open. In such an embodiment, the voltage experienced by the motor 808 is equal to the AC line voltage 802. As another exemplary embodiment, the variable capacity drive circuit 800 can operate in a second state, in which the first four-quadrant switch 804 is open and the second four-quadrant switch 806 is closed. In such an embodiment, the voltage experienced by the motor 808 is zero.

[0072] Now, especially referencing Figures 12a to 12dWhen the four-quadrant switches 804 and 806 operate in multiple states, the controller 1176 can provide a positive trigger angle 1010 and a negative trigger angle 1012. For example, the positive trigger angle 1010 and the negative trigger angle 1012 can define when the first four-quadrant switch 804 and the second four-quadrant switch 806 operate in each of the first and second states.

[0073] As another example, positive trigger angle 1010 and negative trigger angle 1012 can be used to transition between a first state and a second state. Specifically, in one embodiment, controller 1176 can use positive trigger angle 1010 and negative trigger angle 1012 to transition between the first state and the second state at a switching frequency determined by the AC line voltage frequency to control the percentage of voltage applied to compressor 100 during positive half-cycle 1014 and negative half-cycle 1016. In particular, first four-quadrant switch 804 and second four-quadrant switch 806 can transition between the first state and the second state, transitioning at most twice per half-cycle.

[0074] In certain implementations, for example, the switching frequency can be equal to a low-frequency value per half-cycle. For instance, in one implementation, the switching frequency can be equal to or less than approximately 60 Hz per half-cycle. More specifically, in one implementation, the switching frequency can be synchronized with the AC line voltage, such that the state of the four-quadrant switch changes at most twice per half-cycle. In this example, the switching frequency is essentially twice the line voltage frequency (e.g., 120 Hz), at least when the trigger angle is such that... Figure 12a and Figure 12c This is the arrangement shown. In such an implementation, if the switch is as follows... Figure 12b and Figure 12d If the above occurs, the actual switching frequency is equal to 60 Hz. Furthermore, in this embodiment, the switching time can be determined by the firing angle. Moreover, in this embodiment, the timing between the switching between the first and second states, particularly the firing angle, can be used to modulate the voltage applied to the motor 808. Further, the voltage applied to the motor 808 can include: an AC component, specifically, the AC component includes multiple harmonics exceeding the AC line voltage frequency, which contribute to total harmonic distortion; and a direct current (DC) component. In particular, the positive firing angle 1010 and the negative firing angle 1012 can each include different modulation levels for each of the positive half-cycle 1014 and the negative half-cycle 1016. Thus, different modulation levels can cause both the AC and DC components of the voltage in the motor 808.

[0075] Additionally, according to an exemplary embodiment, the timing between the switch (i.e., the positive and negative firing angles) between the first and second states may further include using the DC component of the voltage to bias the oscillation point. Specifically, the DC component of the voltage may be used to bias, for example, the oscillation center point of the piston 130 of a compressor (e.g., to minimize the top dead center volume of the piston 130). The difference between the positive and negative firing angles may be used to modulate the voltage applied to the motor 808, and may also include using the AC component of the voltage to modulate the compressor capacity. Specifically, the AC component of the voltage may be used to modulate the compressor capacity via the stroke length of the piston 130.

[0076] Additionally, according to an exemplary embodiment, the positive firing angle 1010 and the negative firing angle 1012 can be applied at specific times during a half-cycle. Specifically, the positive firing angle 1010 and the negative firing angle 1012 can be applied relative to the zero-crossing point of the AC line voltage. In one example, the positive firing angle 1010 and the negative firing angle 1012 can be applied at the beginning or end of a half-cycle, such as... Figure 12a , Figure 12b , Figure 12c and Figure 12d As shown, applying a positive firing angle of 1010° and a negative firing angle of 1012° at specific times during the half-cycle can minimize the impact on the total harmonic distortion of the AC components.

[0077] Now, especially referencing Figure 12a A positive firing angle of 1010 can be applied at the beginning of a positive half-cycle, and a negative firing angle of 1012 can be applied at the beginning of a negative half-cycle.

[0078] Now, especially referencing Figure 12c A positive firing angle of 1010 can be applied at the end of the positive half-cycle, and a negative firing angle of 1012 can be applied at the end of the negative half-cycle.

[0079] Furthermore, according to an exemplary embodiment, a positive trigger angle 1010 and a negative trigger angle 1012 can be applied so that the two second states are consecutive. Now, particularly referring to… Figure 12b A positive firing angle of 1010 can be applied at the end of the positive half-cycle, and a negative firing angle of 1012 can be applied at the beginning of the negative half-cycle of 1004. Now, specifically refer to... Figure 12d A positive firing angle of 1010 can be applied at the beginning of the positive half-cycle, and a negative firing angle of 1012 can be applied at the end of the negative half-cycle of 1008. For example... Figure 12b and Figure 12d As shown, applying a positive trigger angle of 1010 and a negative trigger angle of 1012 makes the two second states continuous and can reduce the switching frequency.

[0080] Additionally, according to an exemplary embodiment, the positive firing angle 1010 and the negative firing angle 1012 can be changed. Specifically, the positive firing angle 1010 and the negative firing angle 1012 can be increased. For example, the positive firing angle 1010 and the negative firing angle 1012 can be increased equally. Changing the positive firing angle 1010 and the negative firing angle 1012 can reduce the AC component of the voltage in the motor 808. Alternatively, changing the positive firing angle 1010 and the negative firing angle 1012 can reduce the DC component of the voltage in the motor 808. As another example, a difference can be injected between the positive firing angle 1010 and the negative firing angle 1012. The difference between the positive firing angle 1010 and the negative firing angle 1012 can control the DC component of the voltage applied to the motor 808.

[0081] Furthermore, according to an exemplary embodiment, the standard operating mode of the compressor can define a resonant frequency. Specifically, the standard operating mode of the compressor can be defined as a resonant frequency equal to the AC line frequency.

[0082] This written description discloses the invention using examples (including preferred embodiments) and enables those skilled in the art to practice the invention (including making and using any apparatus or system and performing any of the included methods). The patentable scope of the invention is defined by the claims and may include other examples that may be conceived by those skilled in the art. Such other examples are expected to fall within the scope of the claims if they include structural elements that are not distinct from the literal language of the claims, or if they include equivalent structural elements that are not substantially distinct from the literal language of the claims.

Claims

1. A method for operating a variable capacity drive circuit for a compressor, said variable capacity drive circuit having at least a first four-quadrant switch, a second four-quadrant switch, and a motor, characterized in that, The method includes: In a first state, the first four-quadrant switch and the second four-quadrant switch are operated, in which the first four-quadrant switch is closed and the second four-quadrant switch is open, wherein, in the first state, the voltage experienced by the motor is equal to the AC line voltage; In the second state, the first four-quadrant switch and the second four-quadrant switch are operated, in which the first four-quadrant switch is open and the second four-quadrant switch is closed, wherein the voltage experienced by the motor is zero in the second state; A positive trigger angle and a negative trigger angle are provided, which define when the first four-quadrant switch and the second four-quadrant switch operate in each of the first state and the second state; The positive and negative trigger angles are used to switch between the first and second states at a switching frequency determined by the AC line voltage frequency, so as to control the percentage of voltage applied to the compressor during the positive and negative half-cycles. The difference between the positive firing angle and the negative firing angle is injected to control the DC component of the voltage applied to the motor; The DC component of the voltage is used to bias the oscillation center point of the compressor piston to minimize the top dead center volume of the piston; and The capacity of the compressor is modulated using the AC component of the voltage via the stroke length of the piston.

2. The method according to claim 1, characterized in that, Determining the switching frequency using the AC line voltage frequency includes synchronizing the switching frequency to the AC line voltage, such that the first four-quadrant switch and the second four-quadrant switch switch change a maximum of twice per half-cycle.

3. The method according to claim 2, characterized in that, The switching frequency is equal to 60 Hz or 120 Hz.

4. The method according to claim 1, characterized in that, The transition between the first state and the second state using the positive and negative firing angles also includes using the positive and negative firing angles to modulate the voltage applied to the motor, the voltage including an AC component and a DC component.

5. The method according to claim 4, characterized in that, The positive firing angle and the negative firing angle each include different modulation levels for each of the positive half-cycle and the negative half-cycle, to induce the AC component and the DC component of the voltage in the motor.

6. The method according to claim 4, characterized in that, The method further includes applying the positive firing angle and the negative firing angle at the beginning or end of a half-cycle to minimize the effect on the total harmonic distortion of at least one of the AC component or the DC component of the voltage applied to the motor.

7. The method according to claim 6, characterized in that, The method further includes applying the positive trigger angle at the end of the positive half-cycle and applying the negative trigger angle at the beginning of the negative half-cycle, or applying the positive trigger angle at the beginning of the positive half-cycle and applying the negative trigger angle at the end of the negative half-cycle, such that the two second states are consecutive, thereby reducing the switching frequency.

8. The method according to claim 4, characterized in that, The method further includes increasing the positive firing angle and the negative firing angle by equal amounts to reduce the AC component of the voltage in the motor.

9. The method according to claim 4, characterized in that, The standard operating mode of the compressor defines a resonant frequency equal to the AC line frequency.

10. The method according to claim 1, characterized in that, The method further includes using at least one lookup table to determine the positive firing angle and the negative firing angle.

11. A linear compressor, characterized in that, The linear compressor includes: A housing that defines a piston and a cylinder; An electric motor, the electric motor being used to drive the piston and the cylinder; and A variable capacity drive circuit, used to drive the motor, the variable capacity drive circuit comprising: Multiple four-quadrant switches are arranged in a totem-pole configuration between the AC line voltage of the linear compressor and the motor. The plurality of four-quadrant switches includes at least a first four-quadrant switch and a second four-quadrant switch. The first and second four-quadrant switches operate in a first state and a second state, respectively. In the first state, the first four-quadrant switch is closed and the second four-quadrant switch is open, such that the voltage experienced by the motor is equal to the AC line voltage. In the second state, the first four-quadrant switch is open and the second four-quadrant switch is closed, such that the voltage experienced by the motor is zero. A controller, communicatively coupled to the plurality of four-quadrant switches, is configured to perform a plurality of operations, the plurality of operations including: A positive trigger angle and a negative trigger angle are provided, which define when the first four-quadrant switch and the second four-quadrant switch operate in each of the first state and the second state; The positive and negative trigger angles are used to switch between the first and second states at a switching frequency determined by the AC line voltage frequency, so as to control the percentage of voltage applied to the compressor during the positive and negative half-cycles. The difference between the positive firing angle and the negative firing angle is injected to control the DC component of the voltage applied to the motor; The DC component of the voltage is used to bias the oscillation center point of the compressor piston to minimize the top dead center volume of the piston; and The capacity of the compressor is modulated using the AC component of the voltage via the stroke length of the piston.

12. The linear compressor according to claim 11, characterized in that, Determining the switching frequency using the AC line voltage frequency includes synchronizing the switching frequency to the AC line voltage, such that the four-quadrant switch changes at most twice per half-cycle.

13. The linear compressor according to claim 12, characterized in that, The switching frequency is equal to 60 Hz or 120 Hz.

14. The linear compressor according to claim 11, characterized in that, The transition between the first state and the second state using the positive and negative firing angles also includes modulating the voltage applied to the motor using timing between the switches between the first and second states, the voltage including an AC component and a DC component.

15. The linear compressor according to claim 14, characterized in that, The positive firing angle and the negative firing angle each include different modulation levels for each of the positive half-cycle and the negative half-cycle, to induce the AC component and the DC component of the voltage in the motor.

16. The linear compressor according to claim 14, characterized in that, It also includes applying the positive and negative firing angles at the beginning or end of a half-cycle to minimize the total harmonic distortion of at least one of the AC or DC components of the voltage applied to the motor.

17. The linear compressor according to claim 16, characterized in that, It also includes applying the positive trigger angle at the end of the positive half-cycle and applying the negative trigger angle at the beginning of the negative half-cycle, or applying the positive trigger angle at the beginning of the positive half-cycle and applying the negative trigger angle at the end of the negative half-cycle, such that the two second states are consecutive, thereby reducing the switching frequency.

18. A refrigeration appliance, characterized in that, The refrigeration appliance includes: A housing, the housing including at least one chamber for receiving food; A door that allows entry into the at least one chamber; A linear compressor, used for auxiliary cooling of the at least one chamber, the linear compressor comprising: A housing that defines a piston and a cylinder; An electric motor, the electric motor being used to drive the piston and the cylinder; and A variable capacity drive circuit, used to drive the motor, includes: A plurality of four-quadrant switches are arranged in a totem pole configuration between the AC line voltage of the linear compressor and the motor. The plurality of four-quadrant switches include at least a first four-quadrant switch and a second four-quadrant switch, which operate in a first state and a second state. In the first state, the first four-quadrant switch is closed and the second four-quadrant switch is open, such that the voltage experienced by the motor is equal to the AC line voltage. In the second state, the first four-quadrant switch is open and the second four-quadrant switch is closed, such that the voltage experienced by the motor is zero. A controller, communicatively coupled to the plurality of four-quadrant switches, is configured to perform a plurality of operations, the plurality of operations including: A positive trigger angle and a negative trigger angle are provided, which define when the first four-quadrant switch and the second four-quadrant switch operate in each of the first state and the second state; The positive and negative trigger angles are used to switch between the first and second states at a switching frequency determined by the AC line voltage frequency, so as to control the percentage of voltage applied to the compressor during the positive and negative half-cycles. The difference between the positive firing angle and the negative firing angle is injected to control the DC component of the voltage applied to the motor; The DC component of the voltage is used to bias the oscillation center point of the compressor piston to minimize the top dead center volume of the piston; and The capacity of the compressor is modulated using the AC component of the voltage via the stroke length of the piston.

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