Patent Publication Number: US-2022224193-A1

Title: Compressor and air conditioner

Description:
CROSS REFERENCE TO RELATED APPLICATION 
     This application is a U.S. National Stage Application of International Application No. PCT/JP2019/023501 filed on Jun. 13, 2019, the contents of which are incorporated herein by reference. 
    
    
     TECHNICAL FIELD 
     The present invention relates to a compressor and an air conditioner. 
     BACKGROUND 
     Connection states of coils of a motor include a Y connection and a delta connection. In the case of a motor incorporated in a compressor of an air conditioner, one of the Y connection or the delta connection is selected depending on specifications of the compressor (for example, Patent Reference 1). 
     PATENT REFERENCE 
     
         
         Patent Reference 1: Japanese Patent Application Publication No. 2000-232745 
       
    
     However, it is difficult to change the connection state of the coils after the motor is incorporated in the compressor. Thus, it is difficult to flexibly cope with various specifications of the compressor. 
     SUMMARY 
     The present invention is made to solve the problem described above, and an object of the present invention to enable the connection state of coils to be changed in a state where a motor is incorporated in a compressor. 
     A compressor according to the present invention includes a motor including three-phase coils having 6N terminals (where N is an integer), a compression mechanism driven by the motor, a closed container in which the motor and the compression mechanism are housed, a terminal portion electrically connected to the 6N terminals of the coils and protruding outside the closed container, a conductor portion attached to at least a part of the terminal portion to thereby fix a connection state of the coils, and an insulating body covering the conductor portion. 
     According to the present invention, the connection state of the coils is fixed by the conductor portion attached to the terminal portion protruding outside the closed container, and thus the connection state of the coils can be changed in a state where the motor is incorporated in the compressor. As a result, it is possible to flexibly cope with various specifications of the compressor. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a longitudinal sectional view illustrating a compressor according to a first embodiment in which a connection state of coils is fixed to a Y connection. 
         FIG. 2  is a sectional view illustrating a motor according to the first embodiment. 
         FIG. 3  is a diagram illustrating a manner of connection of the coils of the compressor of  FIG. 1 . 
         FIG. 4  is a schematic view illustrating the coils, lead wires, and sockets according to the first embodiment. 
         FIGS. 5(A) and 5(B)  are respectively a sectional view and a perspective view illustrating a first terminal portion and the socket according to the first embodiment. 
         FIG. 6  is a diagram illustrating the connection state of the coils of the compressor of  FIG. 1 . 
         FIG. 7  is a top view illustrating arrangement of the first terminal portion and a second terminal portion according to the first embodiment. 
         FIG. 8  is a schematic view illustrating an inverter connecting portion, a connection fixing portion, the first terminal portion, and the second terminal portion of the compressor of  FIG. 1 . 
         FIG. 9  is a schematic view illustrating the inverter connecting portion, the connection fixing portion, the first terminal portion, the second terminal portion, and an inverter of the compressor of  FIG. 1 . 
         FIG. 10  is a longitudinal sectional view illustrating the compressor of  FIG. 1  in such a manner that outer shapes of the inverter connecting portion and the connection fixing portion can be seen. 
         FIG. 11  is a longitudinal sectional view illustrating another configuration example of the compressor of  FIG. 1 . 
         FIG. 12  is a longitudinal sectional view illustrating the compressor according to the first embodiment in which the connection state of the coils is fixed to a delta connection. 
         FIG. 13  is a diagram illustrating a manner of connection of the coils of the compressor of  FIG. 12 . 
         FIG. 14  is a diagram illustrating the connection state of the coils of the compressor of  FIG. 12 . 
         FIG. 15  is a schematic view illustrating a connection fixing portion, the first terminal portion, the second terminal portion, and the inverter of the compressor of  FIG. 12 . 
         FIG. 16  is a schematic view illustrating the connection fixing portion, the first terminal portion, the second terminal portion, and the inverter of the compressor of  FIG. 12 . 
         FIG. 17  is a longitudinal sectional view illustrating the compressor of  FIG. 12  in such a manner that an outer shape of the connection fixing portion can be seen. 
         FIG. 18  is a graph showing a relationship between a rotation speed and a motor efficiency of the motor according to the first embodiment for each of the Y connection and the delta connection. 
         FIG. 19  is a longitudinal sectional view illustrating a compressor according to a comparative example. 
         FIG. 20  is a diagram illustrating a manner of connection of coils of the compressor of  FIG. 19 . 
         FIG. 21  is a diagram illustrating a manner of connection of coils of a compressor according to a second embodiment in which a connection state of coils is fixed to the Y connection. 
         FIG. 22  is a diagram illustrating the connection state of the coils of the compressor of  FIG. 21 . 
         FIG. 23  is a diagram illustrating a manner of connection of the coils of the compressor according to the second embodiment in which the connection state of the coils is fixed to the delta connection. 
         FIG. 24  is a diagram illustrating the connection state of the coils of the compressor of  FIG. 23 . 
         FIG. 25  is a graph showing a relationship between a rotation speed and a motor efficiency of a motor according to the second embodiment for each of the Y connection and the delta connection. 
         FIG. 26  is a diagram illustrating a manner of connection of coils of a compressor according to a third embodiment. 
         FIG. 27  is a diagram illustrating an example of the manner of connection of the coils of the compressor according to the third embodiment. 
         FIG. 28  is a diagram illustrating another example of the manner of connection of the coils of the compressor according to the third embodiment. 
         FIG. 29  is a graph showing a relationship between a rotation speed and a motor efficiency of a motor according to the third embodiment for each of a serial Y connection, a serial delta connection, a parallel Y connection, and a parallel delta connection. 
         FIG. 30  is a diagram illustrating an air conditioner to which the compressors according to the first through third embodiments are applicable. 
     
    
    
     DETAILED DESCRIPTION 
     Embodiments of the present invention will be described in detail with reference to the drawings. These embodiments are not intended to limit the present invention. 
     First Embodiment 
       FIG. 1  is a longitudinal sectional view illustrating a compressor  100  according to a first embodiment. The compressor  100  is a rotary compressor, and is used for, for example, an air conditioner  400  ( FIG. 30 ). The compressor  100  includes a compression mechanism  110 , a motor  10  for driving the compression mechanism  110 , a shaft  111  coupling the compression mechanism  110  and the motor  10 , and a closed container  101  housing these components. In this example, an axial direction of the shaft  111  is a vertical direction. 
     In the following description, a direction of a center axis Cl as a rotation center of the shaft  111  will be referred to as an “axial direction.” A radial direction about the center axis Cl will be referred to as a “radial direction.” A circumferential direction about the center axis Cl will be referred to as a “circumferential direction” and indicated by an arrow R 1  in  FIG. 2  and other figures. A sectional view in a plane parallel to the center axis Cl will be referred to as a longitudinal sectional view, and a sectional view in a plane perpendicular to the center axis Cl will be referred to as a cross sectional view. 
     The closed container  101  is a container made of a steel sheet, and includes a cylindrical shell  102 , a container top  103  covering an upper portion of the shell  102 , and a container bottom  104  covering a lower portion of the shell  102 . The motor  10  is incorporated in the shell  102  of the closed container  101  by shrink fitting, press fitting, welding, or the like. 
     The container top  103  of the closed container  101  is provided with a discharge pipe  108  for ejecting a refrigerant to the outside, and a first terminal portion  21  and a second terminal portion  22  connected to coils  6  of the motor  10 . The first terminal portion  21  and the second terminal portion  22  will be described later. 
     An accumulator  120  for storing a refrigerant gas is attached to the outer side of the closed container  101 . A refrigerating machine oil for lubricating bearing portions of the compression mechanism  110  is stored in a bottom portion of the closed container  101 . 
     The compression mechanism  110  includes a cylinder  112  having a cylinder chamber  113 , a rolling piston  114  fixed to the shaft  111 , a vane dividing the inside of the cylinder chamber  113  into a suction side and a compression side, and an upper frame  115  and a lower frame  116  closing ends of the cylinder chamber  113  in the axial direction. 
     Each of the upper frame  115  and the lower frame  116  has a bearing portion rotatably supporting the shaft  111 . An upper discharge muffler  117  and a lower discharge muffler  118  are respectively attached to the upper frame  115  and the lower frame  116 . 
     The cylinder  112  has the cylinder chamber  113  of a cylindrical shape about the center axis Cl. An eccentric shaft portion  111   a  of the shaft  111  is located inside the cylinder chamber  113 . The eccentric shaft portion  111   a  has a center eccentric with respect to the center axis Cl. The rolling piston  114  is fitted onto an outer periphery of the eccentric shaft portion  111   a . When the motor  10  rotates, the eccentric shaft portion  111   a  and the rolling piston  114  eccentrically rotate in the cylinder chamber  113 . 
     The cylinder  112  has a suction port  119  through which a refrigerant gas is sucked into the cylinder chamber  113 . A suction pipe  121  communicating with the suction port  119  is attached to the closed container  101 , and the refrigerant gas is supplied from the accumulator  120  to the cylinder chamber  113  through the suction pipe  121 . 
     The compressor  100  is supplied with a mixture of a low-pressure refrigerant gas and liquid refrigerant from a refrigerant circuit of the air conditioner  400  ( FIG. 30 ). When the liquid refrigerant flows into the compression mechanism  110  and is compressed therein, it may cause a failure of the compression mechanism  110 . Thus, the liquid refrigerant and the refrigerant gas are separated in the accumulator  120 , and only the refrigerant gas is supplied to the compression mechanism  110 . 
     As the refrigerant, R410A, R407C, or R22 may be used, for example. From the viewpoint of preventing global warming, a refrigerant having a low global warming potential (GWP) is preferably used. As the low-GWP refrigerant, the following refrigerants can be used, for example. 
     (1) First, a halogenated hydrocarbon having a carbon double bond in its composition, such as hydro-fluoro-olefin(HFO)-1234yf (CF 3 CF═CH 2 ) can be used. The GWP of HFO-1234yf is 4.
 
(2) Further, a hydrocarbon having a carbon double bond in its composition, such as R1270 (propylene), may be used. The GWP of R1270 is 3, which is lower than that of HFO-1234yf, but the flammability of R1270 is higher than that of HFO-1234yf.
 
(3) A mixture containing at least one of a halogenated hydrocarbon having a carbon double bond in its composition or a hydrocarbon having a carbon double bond in its composition, such as a mixture of HFO-1234yf and R32, may be used. The above-described HFO-1234yf is a low-pressure refrigerant and tends to increase a pressure loss, which may lead to degradation in performance of a refrigeration cycle (especially an evaporator). Thus, it is practically preferable to use a mixture of HFO-1234yf with R32 or R41, which is a higher-pressure refrigerant than HFO-1234yf.
 
     The compressor  100  is not limited to a rotary compressor, and may be a scroll compressor or the like. 
     (Configuration of Motor) 
       FIG. 2  is a cross sectional view illustrating the motor  10 . The motor  10  is a motor called an inner rotor type, and includes a rotor  4  and a stator  5  surrounding the rotor  4  from an outer side in the radial direction. An air gap of, for example, 0.3 to 1.0 mm is formed between the rotor  4  and the stator  5 . 
     The rotor  4  includes a cylindrical rotor core  40  and permanent magnets  45  attached to the rotor core  40 . The rotor core  40  is formed by stacking a plurality of steel laminations in the axial direction and integrating the steel laminations by crimping or the like. The steel laminations are, for example, electromagnetic steel sheets. Each of the steel laminations has a thickness of 0.1 to 0.7 mm, and 0.35 mm in this example. A shaft hole  44  is formed at a center of the rotor core  40  in the radial direction, and the shaft  111  described above is fixed in the shaft hole  44  by shrink fitting, press fitting, bonding or the like. 
     A plurality of magnet insertion holes  41  in which the permanent magnets  45  are inserted are formed along an outer periphery of the rotor core  40 . One magnet insertion hole  41  corresponds to one magnetic pole, and a portion between each adjacent two of the magnet insertion holes  41  is an inter-pole portion. The number of magnet insertion holes  41  is six, in this example. In other words, the number of poles is six. It is noted that the number of poles is not limited to six, and only needs to be two or more. Each magnet insertion hole  41  linearly extends in a plane perpendicular to the axial direction. 
     One permanent magnet  45  is inserted in each magnet insertion hole  41 . Each permanent magnet  45  is in the form of a flat plate, and has a width in the circumferential direction of the rotor core  40  and a thickness in the radial direction. The permanent magnet  45  is constituted by, for example, a rare earth magnet containing neodymium (Nd), iron (Fe), and boron (B). 
     Each of the permanent magnets  45  is magnetized in the thickness direction. The permanent magnets  45  inserted in the adjacent magnet insertion holes  41  have opposite magnetic poles on the outer sides in the radial direction. It is noted that each magnet insertion hole  41  may have, for example, a V shape, and two or more permanent magnets  45  may be disposed in each magnet insertion hole  41 . 
     In the rotor core  40 , openings  42  serving as flux barriers are formed at both ends of each magnet insertion hole  41  in the circumferential direction. Thin-walled portions are formed between the openings  42  and the outer periphery of the rotor core  40 . Each thin-walled portion has a width so as to reduce short-circuit magnetic fluxes flowing between adjacent magnetic poles. For example, each thin-walled portion has a width equal to the thickness of each steel lamination. 
     In the rotor core  40 , at least one slit  43  is formed between each magnet insertion hole  41  and the outer periphery of the rotor core  40 . The slit  43  is formed to reduce an increase in iron loss caused by a rotating magnetic field from the stator  5  and to reduce vibration and noise caused by a magnetic attraction force. In this example, five slits  43  are symmetrically disposed with respect to a center of each magnet insertion hole  41  in the circumferential direction, that is, a pole center. The number and positions of the slits  43  may be varied. 
     In the rotor core  40 , through holes  48  and  49  are formed on the inner side with respect to the magnet insertion holes  41  in the radial direction. Each through hole  48  is formed at a position in the circumferential direction corresponding to the inter-pole portion. Each through hole  49  is formed at a position in the circumferential direction corresponding to the pole center and on the outer side with respect to the through hole  48  in the radial direction. The through holes  48  and  49  are used as air holes through which a refrigerant passes or holes through which jigs are inserted. Six through holes  48  and six through holes  49  are formed in this example, but the numbers and positions of the through holes  48  and  49  may be varied. 
     The stator  5  includes a stator core  50 , and coils  6  wound on the stator core  50 . The stator core  50  is formed by stacking a plurality of steel laminations in the axial direction and integrating the steel laminations by crimping or the like. The steel laminations are, for example, electromagnetic steel sheets. Each of the steel laminations has a thickness of 0.1 to 0.7 mm, and 0.35 mm in this example. 
     The stator core  50  includes a yoke  51  having an annular shape about the center axis Cl, and a plurality of teeth  52  extending inward in the radial direction from the yoke  51 . The teeth  52  are arranged at equal intervals in the circumferential direction. The number of teeth  52  is nine in this example. However, the number of the teeth  52  is not limited to nine, and only needs to be two or more. A slot  53  that is a space for accommodating the coil  6  is formed between each two of the teeth  52  adjacent to each other in the circumferential direction. The number of slots  53  is nine, which is equal to the number of the teeth  52 . That is, in the motor  10 , a ratio of the number of poles and the number of slots is 2:3. 
     The stator core  50  is formed by coupling a plurality of split cores  5 A in the circumferential direction, and each split core  5 A includes one tooth  52 . The split cores  5 A are coupled to each other at coupling portions  51   a  provided at ends on the outer peripheral side of the yoke  51 . Thus, the coils  6  can be wound around the teeth  52  in a state where the stator core  50  is expanded in a band shape. It is noted that the stator core  50  is not limited to a structure in which the split cores  5 A are coupled. 
     The coils  6  are constituted by magnet wires, and wound around the teeth  52  by concentrated winding. Each magnet wire has a wire diameter of, for example, 0.8 mm. The number of turns of the coil  6  around one tooth  52  is, for example, 70 turns. The number of turns and the wire diameter of the coil  6  are determined depending on a rotation speed, a torque or other properties of the motor  10 , a supply voltage, or a sectional area of the slot  53 . The coils  6  include a U-phase coil  6 U, a V-phase coil  6 V, and a W-phase coil  6 W. 
     An insulating portion  54  ( FIG. 1 ) made of, for example, a resin such as liquid crystal polymer (LCP) is provided between each end of the stator core  50  in the axial direction and the coils  6 . The insulating portion  54  is formed by attaching a resin compact to the stator core  50  or integrally molding the stator core  50  with a resin. Although not shown in  FIG. 2 , an insulating film having a thickness of 0.1 mm to 0.2 mm and made of a resin such as polyethylene terephthalate (PET) is provided on the inner surface of each slot  53 . 
     As described above, the number of slots (i.e., the number of teeth  52 ) of the stator  5  is nine, and the number of poles of the rotor  4  is six. That is, in the motor  10 , a ratio of the number of poles of the rotor  4  to the number of slots of the stator  5  is 2:3. 
     (Connection State of Coils  6 ) 
       FIG. 3  is a diagram illustrating a manner of connection of the coils  6 U,  6 V, and  6 W of the motor  10 . The coil  6 U is formed by serially connecting coil elements U 1 , U 2 , and U 3  wound around three teeth  52 . In  FIG. 2  described above, characters U 1 , U 2 , and U 3  respectively denote the teeth  52  around which the coil elements U 1 , U 2 , and U 3  are wound. The coil  6 U includes a first terminal  6   a  and a second terminal  6   b . The first terminal  6   a  and the second terminal  6   b  are open in the motor  10 . 
     The coil  6 V is formed by serially connecting coil elements V 1 , V 2 , and V 3  wound around three teeth  52 . In  FIG. 2  described above, characters V 1 , V 2 , and V 3  respectively denote the teeth  52  around which the coil elements V 1 , V 2 , and V 3  are wound. The coil  6 V includes a first terminal  6   c  and a second terminal  6   d . The first terminal  6   c  and the second terminal  6   d  are open in the motor  10 . 
     The coil  6 W is formed by serially connecting coil elements W 1 , W 2 , and W 3  wound around three teeth  52 . In  FIG. 2  described above, characters W 1 , W 2 , and W 3  respectively denote the teeth  52  around which the coil elements W 1 , W 2 , and W 3  are wound. The coil  6 W includes a first terminal  6   e  and a second terminal  6   f . The first terminal  6   e  and the second terminal  6   f  are open in the motor  10 . 
     The coils  6 U,  6 V, and  6 W include the six terminals  6   a  through  6   f  in total. When N denotes an integer, the total number of terminals of the coils  6 U,  6 V, and  6 W is represented by 6×N. A case where N is 1 will be described herein. It is noted that N may be 2 or more, and may be, for example, 3 as described later (see  FIG. 26 ). 
     A lead wire  61 U is connected to the first terminal  6   a  of the coil  6 U, and a lead wire  62 U is connected to the second terminal  6   b  of the coil  6 U. A lead wire  61 V is connected to the first terminal  6   c  of the coil  6 V, and a lead wire  62 V is connected to the second terminal  6   d  of the coil  6 V. A lead wire  61 W is connected to the first terminal  6   e  of the coil  6 W, and a lead wire  62 W is connected to the second terminal  6   f  of the coil  6 W. Each of the lead wires  61 U,  62 U,  61 V,  62 V,  61 W, and  62 W is constituted by an electrically conductive lead. 
       FIG. 4  is a schematic view illustrating the stator  5  of the motor  10 , the lead wires  61  and  62 , and sockets  11  and  12 . Plugs  55 U,  55 V,  55 W,  56 U,  56 V, and  56 W are provided on the insulating portion  54  of the stator  5 . 
     The plug  55 U connects the first terminal  6   a  ( FIG. 3 ) of the coil  6 U to the lead wire  61 U, and the plug  56 U connects the second terminal  6   b  ( FIG. 3 ) of the coil  6 U to the lead wire  62 U. The plug  55 V connects the first terminal  6   c  ( FIG. 3 ) of the coil  6 V to the lead wire  61 V, and the plug  56 V connects the second terminal  6   d  ( FIG. 3 ) of the coil  6 V to the lead wire  62 V. The plug  55 W connects the first terminal  6   e  ( FIG. 3 ) of the coil  6 W to the lead wire  61 W, and the plug  56 W connects the second terminal  6   f  ( FIG. 3 ) of the coil  6 W to the lead wire  62 W. 
     The lead wires  61 U,  61 V, and  61 W are connected to the first socket  11 . The lead wires  62 U,  62 V, and  62 W are connected to the second socket  12 . The sockets  11  and  12  are not shown in  FIG. 3  described above. 
     As illustrated in  FIG. 1 , the first socket  11  is attached to the first terminal portion  21  mounted on the container top  103 . The second socket  12  is attached to the second terminal portion  22  mounted on the container top  103 . 
     An inverter connecting portion  31  attached to lead wires  71 U,  71 V, and  71 C from the inverter  70  is attached to the first terminal portion  21 . A connection fixing portion  32  is attached to the second terminal portion  22 . The first terminal portion  21  and the second terminal portion  22  will be collectively referred to as terminal portions  21  and  22 . 
       FIG. 5(A)  is a sectional view illustrating the first socket  11  and the first terminal portion  21 .  FIG. 5(B)  is a perspective view illustrating the first socket  11  and the first terminal portion  21 . 
     The first terminal portion  21  includes three pins  21 U,  21 V, and  21 W that are conductors, a base member  210  fixed to the container top  103  of the closed container  101 , and three insulating portions  211  disposed between the base member  210  and the pins  21 U,  21 V, and  21 W. The insulating portions  211  are made of an insulating body such as glass or silicon rubber. The first terminal portion  21  will also be referred to as a connection terminal portion or a glass terminal. 
     The base member  210  is made of a metal such as iron, and fitted into an attachment hole  106  formed in a wall portion  105  of the container top  103 . The base member  210  has a disk shape in this example, but may have other shapes. The pins  21 U,  21 V, and  21 W pass through holes formed in the base member  210 , and extend from the inside to the outside of the closed container  101 . The insulating portions  211  are interposed between the pins  21 U,  21 V, and  21 W and the holes. 
     The first socket  11  has three holes into which the pins  21 U,  21 V, and  21 W are fitted. End portions of the lead wires  61 U,  61 V, and  61 W are fixed to the first socket  11 . In the first socket  11 , the pins  21 U,  21 V, and  21 W are respectively connected to the lead wires  61 U,  61 V, and  61 W. 
     Although  FIGS. 5(A) and 5(B)  illustrate the first terminal portion  21  and the first socket  11 , the second terminal portion  22  and the second socket  12  are configured similarly to the first terminal portion  21  and the first socket  11 . Specifically, the second terminal portion  22  includes pins  22 U,  22 V, and  22 W, a base member  220 , and an insulating portion  221  ( FIG. 3 ). 
     The number of pins  21 U,  21 V, and  21 W of the first terminal portion  21  is 3N. Similarly, the number of the pins  22 U,  22 V, and  22 W of the second terminal portion  22  is 3N. That is, the total number of pins of the first terminal portion  21  and the second terminal portion  22  is 6N. As described above, N is an integer, and is one in this example, but may be two or more. 
     As described above, the lead wires  61 U,  61 V, and  61 W are connected to the pins  21 U,  21 V, and  21 W of the first terminal portion  21  via the first socket  11 . As illustrated in  FIG. 3 , the pins  21 U,  21 V, and  21 W of the first terminal portion  21  are connected to the lead wires  71 U,  71 V, and  71 W of the inverter  70  via the inverter connecting portion  31 . That is, the first terminals  6   a ,  6   c , and  6   e  of the coils  6 U,  6 V, and  6 W are electrically connected to the inverter  70 . 
     In contrast, the lead wires  62 U,  62 V, and  62 W are connected to the pins  22 U,  22 V, and  22 W of the second terminal portion  22 . The pins  22 U,  22 V, and  22 W of the second terminal portion  22  are electrically connected to one another by a conductor portion  33  in the connection fixing portion  32 . That is, the second terminals  6   b ,  6   d , and  6   f  of the coils  6 U,  6 V, and  6 W are electrically connected to one another. 
       FIG. 6  is a diagram illustrating a connection state of the coils  6 U,  6 V, and  6 W of the compressor  100  of  FIG. 1 . As described above, the second terminals  6   b ,  6   d , and  6   f  of the coils  6 U,  6 V, and  6 W are electrically connected to one another by the conductor portion  33  of the connection fixing portion  32 . Thus, the coils  6 U,  6 V, and  6 W are connected to one another at the second terminals  6   b ,  6   d , and  6   f  serving as a neutral point. In other words, the coils  6 U,  6 V and  6 W are connected in a Y connection. 
     A state where the coils  6 U,  6 V, and  6 W in which coil elements of each phase are connected in series are connected in the Y connection as above will be referred to as a serial Y connection. 
       FIG. 7  is a top view illustrating arrangement of the first terminal portion  21  and the second terminal portion  22 . The first terminal portion  21  and the second terminal portion  22  are disposed on the outer side of the closed container  101 , more specifically, on an upper surface portion of the container top  103 . Since the upper surface portion of the container top  103  is flat, the first terminal portion  21  and the second terminal portion  22  can be easily disposed. 
       FIG. 8  is a schematic view illustrating the first terminal portion  21 , the second terminal portion  22 , the inverter connecting portion  31 , and the connection fixing portion  32 . The inverter connecting portion  31  has holes  31 U,  31 V, and  31 W as fitting portions into which the pins  21 U,  21 V, and  21 W of the first terminal portion  21  are fitted. The holes  31 U,  31 V, and  31 W are formed in, for example, an insulating substrate  310 . The substrate  310  is made of, for example, a resin. 
     The connection fixing portion  32  has holes  32 U,  32 V, and  32 W into which the pins  22 U,  22 V, and  22 W of the second terminal portion  22  are fitted. The holes  32 U,  32 V, and  32 W are formed in, for example, an insulating substrate  320 . The holes  32 U,  32 V, and  32 W are connected to one another by the conductor portion  33 . The substrate  320  is covered with an insulating cover  34  ( FIG. 1 ). 
     The substrate  320  is made of, for example, an insulating body such as a resin. The conductor portion  33  is made of a conductor such as a metal. The insulating cover  34  is made of an insulating body such as a resin. The insulating cover  34  may be formed integrally with the substrate  320 . 
       FIG. 9  is a schematic view illustrating the first terminal portion  21 , the second terminal portion  22 , the inverter connecting portion  31 , the connection fixing portion  32 , and the inverter  70 . The inverter connecting portion  31  and the connection fixing portion  32  are attached to the upper surface portion of the container top  103  so that the inverter connecting portion  31  overlaps with the first terminal portion  21  and the connection fixing portion  32  overlaps with the second terminal portion  22 . 
     The pins  21 U,  21 V, and  21 W fitted into the holes  31 U,  31 V, and  31 W of the inverter connecting portion  31  are connected to the lead wires  71 U,  71 V, and  71 W of the inverter  70 . 
     The pins  22 U,  22 V, and  22 W fitted into the holes  32 U,  32 V, and  32 W of the connection fixing portion  32  are electrically connected to one another by the conductor portion  33 . Accordingly, as illustrated in  FIG. 6 , the second terminals  6   b ,  6   d , and  6   f  are connected to one another, and the Y connection is obtained. 
       FIG. 10  is a longitudinal sectional view illustrating the compressor  100  in such a manner that outer shapes of the inverter connecting portion  31  and the connection fixing portion  32  can be seen. As illustrated in  FIG. 10 , the pins  21 U,  21 V, and  21 W of the first terminal portion  21  are covered with the inverter connecting portion  31 , and the pins  22 U,  22 V, and  22 W of the second terminal portion  22  are covered with the connection fixing portion  32 . Thus, the pins  21 U,  21 V,  21 W,  22 U,  22 V, and  22 W are not exposed to the outside. 
     In  FIGS. 1, 10  and the like, the first terminal portion  21  and the second terminal portion  22  are disposed on the upper surface portion of the container top  103 . Alternatively, as illustrated in  FIG. 11 , the first terminal portion  21  and the second terminal portion  22  may be disposed on a side surface portion of the closed container  101 , that is, the outer periphery of the shell  102 . 
       FIG. 12  is a longitudinal sectional view illustrating the compressor  100  in which the connection state of the coils  6 U,  6 V, and  6 W is fixed to a delta connection. In  FIG. 12 , the compressor  100  includes a connection fixing portion  35  instead of the inverter connecting portion  31  and the connection fixing portion  32  (see  FIG. 1  and the like). The connection fixing portion  35  is attached to both the first terminal portion  21  and the second terminal portion  22 . 
       FIG. 13  is a diagram illustrating a manner of connection of the coils  6 U,  6 V, and  6 W of the compressor  100  of  FIG. 12 . The connection fixing portion  35  includes a conductor portion  36   a  connecting the pin  21 U and the pin  22 W to each other, a conductor portion  36   b  connecting the pin  21 V and the pin  22 U to each other, and a conductor portion  36   c  connecting the pin  21 W and the pin  22 V to each other. Each of the conductor portions  36   a ,  36   b , and  36   c  is made of, for example, a conductive body such as copper. 
     Accordingly, the first terminal  6   a  of the coil  6 U is connected to the second terminal  6   f  of the coil  6 W. The first terminal  6   c  of the coil  6 V is connected to the second terminal  6   b  of the coil  6 U. The first terminal  6   e  of the coil  6 W is connected to the second terminal  6   d  of the coil  6 V. 
       FIG. 14  is a diagram illustrating a connection state of the coils  6 U,  6 V, and  6 W of the compressor  100  of  FIG. 12 . As described above, the first terminal  6   a  of the coil  6 U is connected to the second terminal  6   f  of the coil  6 W, the first terminal  6   c  of the coil  6 V is connected to the second terminal  6   b  of the coil  6 U, and the first terminal  6   e  of the coil  6 W is connected to the second terminal  6   d  of the coil  6 V. Thus, the connection state of the coils  6 U,  6 V, and  6 W is the delta connection. 
     A state where the coils  6 U,  6 V, and  6 W in which coil elements of each phase are connected in series are connected in the delta connection as above will be referred to as a serial delta connection. 
       FIG. 15  is a schematic view illustrating the first terminal portion  21 , the second terminal portion  22 , and the connection fixing portion  35 . The connection fixing portion  35  has holes  31 U,  31 V, and  31 W serving as fitting portions (first fitting portions) into which the pins  21 U,  21 V, and  21 W of the first terminal portion  21  are fitted, and holes  32 U,  32 V, and  32 W serving as fitting portions (second fitting portions) into which the pins  22 U,  22 V, and  22 W of the second terminal portion  22  are fitted. The holes  31 U,  31 V,  31 W,  32 U,  32 V, and  32 W are formed in, for example, an insulating substrate  350 . 
     The hole  31 U and the hole  32 W are connected to each other via the conductor portion  36   a . The hole  31 V and the hole  32 U are connected to each other via the conductor portion  36   b . The hole  31 W and the hole  32 V are connected to each other via the conductor portion  36   c . The conductor portions  36   a ,  36   b , and  36   c  are formed in the substrate  350 . The substrate  350  is covered with an insulating cover  37  ( FIG. 12 ). 
     The substrate  350  is made of, for example, an insulating body such as a resin. Each of the conductor portions  36   a ,  36   b , and  36   c  is made of a conductive body such as a metal. The insulating cover  37  is made of an insulating body such as a resin. The insulating cover  37  may be formed integrally with the substrate  350 . 
       FIG. 16  is a schematic view illustrating the first terminal portion  21 , the second terminal portion  22 , the connection fixing portion  35 , and the inverter  70 . The connection fixing portion  35  is attached to the upper surface portion of the container top  103  so that the connection fixing portion  35  overlaps with the first terminal portion  21  and the second terminal portion  22 . 
     The pins  21 U,  21 V, and  21 W fitted into the holes  31 U,  31 V, and  31 W of the connection fixing portion  35  are respectively connected to the lead wires  71 U,  71 V, and  71 W of the inverter  70 . 
     Thus, the first terminal  6   a  of the coil  6 U and the second terminal  6   f  of the coil  6 W ( FIG. 13 ) are connected to the lead wire  71 U. The first terminal  6   c  of the coil  6 V and the second terminal  6   b  of the coil  6 U ( FIG. 13 ) are connected to the lead wire  71 V. The first terminal  6   e  of the coil  6 W and the second terminal  6   d  of the coil  6 V ( FIG. 13 ) are connected to the lead wire  71 W. 
       FIG. 17  is a longitudinal sectional view illustrating the compressor  100  in such a manner that an outer shape of the connection fixing portion  35  can be seen. As illustrated in  FIG. 17 , the pins  21 U,  21 V, and  21 W of the first terminal portion  21  and the pins  22 U,  22 V, and  22 W of the second terminal portion  22  are covered with the connection fixing portion  35 . Thus, the pins  21 U,  21 V,  21 W,  22 U,  22 V, and  22 W are not exposed to the outside. 
       FIG. 18  is a graph showing a relationship between a rotation speed and a motor efficiency of the motor  10  for each of the Y connection and the delta connection. The motor  10  is controlled by the inverter  70  using pulse width modulation (PWM) control. 
     An output voltage of the inverter  70  is equal to the sum of an induced voltage generated when magnetic fluxes of the permanent magnets  45  are interlinked with the coils  6  of the stator  5  during rotation of the rotor  4 , and a voltage generated by resistance and inductance of the coils  6 . When the output voltage of the inverter  70  exceeds an inverter maximum output voltage, field-weakening control is performed, and the motor efficiency decreases accordingly. 
     A comparison between the Y connection and the delta connection shows that an inter-terminal voltage of the coils  6  in the delta connection is 1/√3 of an inter-terminal voltage of the coils  6  in the Y connection. 
     For the same load torque, an inverter current in the Y connection is 1/√3 of an inverter current in the delta connection. As the inverter current decreases, a conduction loss of an inverter circuit decreases, and the motor efficiency increases. An iron loss due to current ripple is smaller in the Y connection than that in the delta connection. 
     The motor efficiently in the Y connection is higher than that in the delta connection as above. However, in a high-rotation speed range, the output voltage of the inverter  70  reaches the inverter maximum output voltage and field-weakening control is performed. Thus, the Y connection in which the inter-terminal voltage is high is disadvantageous. 
     For this reason, as shown in  FIG. 18 , the Y connection provides a higher motor efficiency in a low-rotation speed range, whereas the delta connection provides a higher motor efficiency in a high-rotation speed range. 
     In  FIG. 18 , both a curve showing the motor efficiency in the Y connection and a curve showing the motor efficiency in the delta connection show decreases after peaks. This is caused by the start of field-weakening control. Since the induced voltage increases as the rotation speed increases, the motor efficiency decreases due to a weakening current, a conduction loss of the inverter  70 , and a copper loss of the coils  6 . 
     For this reason, in a case where the maximum rotation speed of the compressor  100  is a low rotation speed, the connection state of the coils  6 U,  6 V, and  6 W is set to the Y connection. In a case where the maximum rotation speed of the compressor  100  is a high rotation speed, the connection state of the coils  6 U,  6 V, and  6 W is set to the delta connection. However, in general, after the motor  10  is incorporated in the compressor  100 , it is difficult to change the connection state of the coils  6 U,  6 V, and  6 W. 
       FIG. 19  is a longitudinal sectional view illustrating a compressor  100  according to a comparative example. In the comparative example, a connection state of coils  6 U,  6 V, and  6 W of a motor  10  is fixed to the Y connection in the motor  10 . 
       FIG. 20  is a diagram illustrating a manner of connection of the coils  6 U,  6 V, and  6 W of the compressor  100  of the comparative example. First terminals  6   a ,  6   c , and  6   e  of the coils  6 U,  6 V, and  6 W are connected to lead wires  61 U,  61 V, and  61 W, and connected to an inverter connecting portion  31  via a first socket  11  ( FIG. 19 ). 
     Second terminals  6   b ,  6   d , and  6   f  of the coils  6 U,  6 V, and  6 W are connected to one another in the motor  10  and constitute a neutral point 6N. Since the connection state of  6 U,  6 V, and  6 W is the Y connection, the motor  10  provides a high motor efficiency in the low-rotation speed range. 
     However, the connection state of the coils  6 U,  6 V, and  6 W is fixed in the motor  10 . Thus, in a case where the maximum rotation speed of the compressor  100  is changed to a high rotation speed after the motor  10  is incorporated in the compressor  100 , it is difficult to change the connection state of the coils  6 U,  6 V, and  6 W to the delta connection. 
     If the connection state of the coils  6 U,  6 V, and  6 W is fixed to the motor  10  as above, it is necessary to manufacture the compressors  100  including the motors  10  having different characteristics for the maximum rotation speeds of the compressors  100 . Accordingly, the number of types of the compressors  100  increases. In addition, if the common motor  10  is used for the compressors  100  having different maximum rotation speeds, the motor efficiency of each compressor  100  decreases, and an output range of each compressors  100  decreases. 
     In contrast, in the first embodiment, the terminals  6   a  through  6   f  of the coils  6 U,  6 V, and  6 W are open in the motor  10 , and the connection state of the coils  6 U,  6 V, and  6 W is fixed to the Y connection or the delta connection by the connection fixing portion  32  ( FIG. 3 ) or the connection fixing portion  35  ( FIG. 13 ). Thus, even after the motor  10  is incorporated in the compressor  100 , the connection state of the coils  6 U,  6 V, and  6 W can be changed from outside the compressor  100 . 
     That is, electrical characteristics of the motor  10  can be changed by replacing the connection fixing portion  32  ( FIG. 3 ) and the connection fixing portion  35  ( FIG. 13 ) of the compressor  100  with each other. Accordingly, it becomes possible to flexibly cope with various specifications of the compressor  100 . 
     Advantages of Embodiment 
     As described above, in the first embodiment, the compressor  100  includes the coils  6 U,  6 V, and  6 W having the 6N terminals  6   a  through  6   f , the terminal portions  21  and  22  electrically connected to the terminals  6   a  through  6   f  and protruding outside the closed container  101 , the conductor portion  33  ( 36   a ,  36   b , and  36   c ) attached to at least a part of the terminal portions  21  and  22  to fix the connection state of the coils  6 U,  6 V, and  6 W, and the insulating cover  34  ( 37 ) covering at least the conductor portion  33  ( 36   a ,  36   b , and  36   c ). Thus, the connection state of the coils  6 U,  6 V, and  6 W can be changed after the motor  10  is incorporated in the compressor  10 , and an optimum connection state can be obtained depending on specifications of the compressor  100 . As a result, an operation efficiency of the compressor  100  can be enhanced. 
     Since the first terminal portion  21  electrically connected to at least three of the 6N terminals of the coils  6 U,  6 V, and  6 W is provided, the inverter  70  can be electrically connected to the coils  6 U,  6 V, and  6 W outside the compressor  100 . 
     In the case where the connection state of the coils  6 U,  6 V, and  6 W is fixed to the Y connection by the conductor portion  33  of the connection fixing portion  32 , the high motor efficiency can be obtained in the low-rotation speed range. 
     In the case where the connection state of the coils  6 U,  6 V, and  6 W is fixed to the delta connection by the conductor portions  36   a ,  36   b , and  36   c  of the connection fixing portion  35 , the high motor efficiency can be obtained in the high-rotation speed range. 
     The second terminal portion  22  includes the base member  220  fixed to the wall portion  105  of the closed container  101  and the pins  22 U,  22 V, and  22 W attached to the base member  220  and extending from the inside to the outside of the closed container  101 . Thus, the connection state of the coils  6 U,  6 V, and  6 W can be changed by using the pins  22 U,  22 V, and  22 W outside the closed container  101 . 
     Since the connection fixing portion  32  has the holes  32 U,  32 V, and  32 W into which the pins  22 U,  22 V, and  22 W of the second terminal portion  22  are fitted, the Y connection of the coils  6 U,  6 V, and  6 W can be obtained by using the conductor portion  33 . 
     Since the connection fixing portion  35  has the holes  31 U,  31 V, and  31 W into which the pins  21 U,  21 V, and  21 W of the first terminal portion  21  are fitted, and the holes  32 U,  32 V, and  32 W into which the pins  22 U,  22 V, and  22 W of the second terminal portion  22  are fitted, the delta connection of the coils  6 U,  6 V, and  6 W can be obtained by using the conductor portions  36   a ,  36   b , and  36   c.    
     Since the coils  6 U,  6 V, and  6 W include two or more coil elements of each phase and the two or more coil elements are connected in series in the motor  10 , a higher motor efficiency can be obtained in the low-rotation speed range, as compared to the case where the coils elements of each phase are connected in parallel. 
     Since the first terminal portion  21  and the second terminal portion  22  are attached to the upper surface portion of the closed container  101 , the first terminal portion  21  and the second terminal portion  22  can be placed on a flat surface, and thus the manufacturing of the compressor  100  is facilitated. 
     Since the lead wires  61 U,  61 V,  61 W,  62 U,  62 V, and  62 W are connected to the terminals  6   a  through  6   f  of the coils  6 U,  6 V, and  6 W, and these lead wires are connected to the first terminal portion  21  and the second terminal portion  22  via the sockets  11  and  12 , the connecting portions of the terminals  6   a  through  6   f  of the coils  6 U,  6 V, and  6 W can be led to the outside of the closed container  101 . 
     Second Embodiment 
     Next, a second embodiment will be described.  FIG. 21  is a diagram illustrating a manner of connection of coils  6 U,  6 V, and  6 W of a compressor  100  according to a second embodiment in which a connection state is fixed to the Y connection. 
     In the first embodiment described above, the coil elements U 1 , U 2 , and U 3  of the coil  6 U are connected in series, the coil elements V 1 , V 2 , and V 3  of the coil  6 V are connected in series, and the coil elements W 1 , W 2 , and W 3  of the coil  6 W are connected in series. 
     In contrast, in the second embodiment, coil elements U 1 , U 2 , and U 3  of a coil  6 U are connected in parallel, coil elements V 1 , V 2 , and V 3  of a coil  6 V are connected in parallel, and coil elements W 1 , W 2 , and W 3  of a coil  6 W are connected in parallel. 
     In  FIG. 21 , first terminals  6   a ,  6   c , and  6   e  of the coils  6 U,  6 V, and  6 W are connected to lead wires  61 U,  61 V, and  61 W, and connected to a first terminal portion  21 . Second terminals  6   b ,  6   d , and  6   f  of the coils  6 U,  6 V, and  6 W are connected to lead wires  62 U,  62 V, and  62 W, and connected to a second terminal portion  22 . 
     An inverter connecting portion  31  is attached to the first terminal portion  21 , and a connection fixing portion  32  is attached to the second terminal portion  22 . As described in the first embodiment, the inverter connecting portion  31  is connected to the inverter  70 . The connection fixing portion  32  includes pins  22 U,  22 V, and  22 W and a conductor portion  33  connecting these pins as described in the first embodiment. 
       FIG. 22  is a diagram illustrating a manner of connection of the coils  6 U,  6 V, and  6 W of the compressor  100  of  FIG. 21 . As described above, the second terminals  6   b ,  6   d , and  6   f  of the coils  6 U,  6 V, and  6 W are electrically connected to one another by the connection fixing portion  32 . Thus, the coils  6 U,  6 V, and  6 W are connected to one another at the second terminals  6   b ,  6   d , and  6   f  serving as a neutral point. In other words, the coils  6 U,  6 V and  6 W are connected in the Y connection. 
     A state where the coils  6 U,  6 V, and  6 W in which coil elements of each phase are connected in parallel are connected in the Y connection as above will be referred to as a parallel Y connection. 
       FIG. 23  is a diagram illustrating a manner of connection of the coils  6 U,  6 V, and  6 W of the compressor  100  according to the second embodiment in which the connection state is fixed to the delta connection. A connection fixing portion  35  is attached to the first terminal portion  21  and the second terminal portion  22 . 
     As in the first embodiment, the connection fixing portion  35  includes a conductor portion  36   a  connecting the pin  21 U and the pin  22 W to each other, a conductor portion  36   b  connecting the pin  21 V and the pin  22 U to each other, and a conductor portion  36   c  connecting the pin  21 W and the pin  22 V to each other. 
       FIG. 24  is a diagram illustrating a connection state of the coils  6 U,  6 V, and  6 W of the compressor  100  of  FIG. 23 . As described above, the first terminal  6   a  of the coil  6 U is connected to the second terminal  6   f  of the coil  6 W, the first terminal  6   c  of the coil  6 V is connected to the second terminal  6   b  of the coil  6 U, and the first terminal  6   e  of the coil  6 W is connected to the second terminal  6   d  of the coil  6 V. Thus, the connection state of the coils  6 U,  6 V, and  6 W is the delta connection. 
     A state where the coils  6 U,  6 V, and  6 W in which coil elements of each phase are connected in parallel are connected in the delta connection as above will be referred to as a parallel delta connection. 
       FIG. 25  is a graph showing a relationship between a rotation speed and a motor efficiency of the motor  10  for each of the parallel Y connection and the parallel delta connection. As in the case of the serial connections illustrated in  FIG. 18 , the parallel Y connection provides a higher motor efficiency in the low-rotation speed range, whereas the parallel delta connection provides a higher motor efficiency in the high-rotation speed range. 
     Thus, in a case where the maximum rotation speed of the compressor  100  is a low rotation speed, the connection state of the coils  6 U,  6 V, and  6 W is fixed to the Y connection, as illustrated in  FIG. 21 . In a case where the rotation speed of the compressor  100  is a high rotation speed, the connection state of the coils  6 U,  6 V, and  6 W is fixed to the delta connection, as illustrated in  FIG. 23 . 
     Since the first terminal portion  21  and the second terminal portion  22  protrude outside the closed container  101  of the compressor  100 , the connection state of the coils  6 U,  6 V, and  6 W can be changed even after the compressor  100  is assembled. 
     As described above, in the second embodiment, the connection state of the coils  6 U,  6 V, and  6 W can be changed between the parallel Y connection and the parallel delta connection after the motor  10  is incorporated in the compressor  100 . Accordingly, it becomes possible to flexibly cope with various specifications of the compressor  100 , and the operation efficiency of the compressor  100  can be enhanced. 
     Since the coils  6 U,  6 V, and  6 W include two or more coil elements of each phase and the two or more coil elements are connected in parallel in the motor  10 , a higher motor efficiency can be obtained in the high-rotation speed range, as compared to the case where the coils elements of each phase are connected in series. 
     Third Embodiment 
     Next, a third embodiment will be described.  FIG. 26  is a diagram illustrating a manner of connection of coils  6 U,  6 V, and  6 W of a compressor  100  according to a third embodiment. 
     In the first embodiment described above, the connection state of the coils  6 U,  6 V, and  6 W in which coil elements of each phase are connected in series is changeable between the Y connection and the delta connection. In the second embodiment described above, the connection state of the coils  6 U,  6 V, and  6 W in which coil elements of each phase are connected in parallel is changeable between the Y connection and the delta connection. 
     In contrast, in the third embodiment, the connection state is changeable between the Y connection and the delta connection and is also changeable between the serial connection and the parallel connection. Specifically, the connection state of the coils  6 U,  6 V, and  6 W is changeable among the serial Y connection ( FIG. 6 ), the serial delta connection ( FIG. 14 ), the parallel Y connection ( FIG. 22 ), and the parallel delta connection ( FIG. 24 ). 
     The compressor  100  according to the third embodiment includes six terminal portions  81  through  86 , instead of the first terminal portion  21  and the second terminal portion  22  ( FIG. 1 ) described in the first embodiment. Each of the terminal portions  81  through  86  protrudes outside the closed container  101 . As is the case with the first terminal portion  21  ( FIG. 5(A) ), each of the terminal portions  81  through  86  includes three pins, a base portion, and an insulating portion. 
     In the third embodiment, the coils  6 U,  6 V, and  6 W include  18  terminals in total. That is, two terminals are provided for each coil element of the coils  6 U,  6 V, and  6 W. When N denotes an integer, the total number of terminals of the coils  6 U,  6 V, and  6 W is represented by 6×N. In this example, N is 3. 
     A first terminal U 11  of a coil element U 1  of the coil  6 U is connected to a pin  81 U of the terminal portion  81  via a lead wire  61 U, and a second terminal U 12  of the coil element U 1  is connected to a pin  82 U of the terminal portion  82  via a lead wire  62 U. 
     A first terminal V 11  of a coil element V 1  of the coil  6 V is connected to a pin  81 V of the terminal portion  81  via a lead wire  61 V, and a second terminal V 12  of the coil element V 1  is connected to a pin  82 V of the terminal portion  82  via a lead wire  62 V. 
     A first terminal W 11  of a coil element W 1  of the coil  6 W is connected to a pin  81 W of the terminal portion  81  via a lead wire  61 W, and a second terminal W 12  of the coil element W 1  is connected to a pin  82 W of the terminal portion  82  via a lead wire  62 W. 
     A first terminal U 21  of a coil element U 2  of the coil  6 U is connected to a pin  83 U of the terminal portion  83  via a lead wire  63 U, and a second terminal U 22  of the coil element U 2  is connected to a pin  84 U of the terminal portion  84  via a lead wire  64 U. 
     A first terminal V 21  of a coil element V 2  of the coil  6 V is connected to a pin  83 V of the terminal portion  83  via a lead wire  63 V, and a second terminal V 22  of the coil element V 2  is connected to a pin  84 V of the terminal portion  84  via a lead wire  64 V. 
     A first terminal W 21  of a coil element W 2  of the coil  6 W is connected to a pin  83 W of the terminal portion  83  via a lead wire  63 W, and a second terminal W 22  of the coil element W 2  is connected to a pin  84 W of the terminal portion  84  via a lead wire  64 W. 
     A first terminal U 31  of a coil element U 3  of the coil  6 U is connected to a pin  85 U of the terminal portion  85  via a lead wire  65 U, and a second terminal U 32  of the coil element U 3  is connected to a pin  86 U of the terminal portion  86  via a lead wire  66 U. 
     A first terminal V 31  of a coil element V 3  of the coil  6 V is connected to a pin  85 V of the terminal portion  85  via a lead wire  65 V, and a second terminal V 32  of the coil element V 3  is connected to a pin  86 V of the terminal portion  86  via a lead wire  66 V. 
     A first terminal W 31  of a coil element W 3  of the coil  6 W is connected to a pin  85 W of the terminal portion  85  via a lead wire  65 W, and a second terminal W 32  of the coil element W 3  is connected to a pin  86 W of the terminal portion  86  via a lead wire  66 W. 
     A connection fixing portion  38  electrically connects the pins  81 U through  86 W of the terminal portions  81  through  86  so that the connection state of the coils  6 U,  6 V, and  6 W is one of the serial Y connection ( FIG. 6 ), the serial delta connection ( FIG. 14 ), the parallel Y connection ( FIG. 22 ), or the parallel delta connection ( FIG. 24 ). 
     In this example, four connection fixing portions  38  respectively corresponding to the serial Y connection ( FIG. 6 ), the serial delta connection ( FIG. 14 ), the parallel Y connection ( FIG. 22 ), and the parallel delta connection ( FIG. 24 ) are provided. Each of the connection fixing portions  38  includes an insulating cover  39  covering the pins  81 U through  86 W of the terminal portions  81  through  86 . 
     For example, the connection fixing portion  38 A illustrated in  FIG. 27  connects the pins  82 U and  83 U to each other, connects the pins  84 U and  85 U to each other, connects the pins  82 V and  83 V to each other, connects the pins  84 V and  85 V to each other, connects the pins  82 W and  83 W to each other, and connects the pins  84 W and  85 W to each other. Accordingly, the connection state of the coils  6 U,  6 V, and  6 W of each phase is the serial connection. 
     The connection fixing portion  38 A also connects the pins  86 U,  86 V, and  86 W to one another. Accordingly, the connection state of the coils  6 U,  6 V, and  6 W is the serial Y connection ( FIG. 6 ). The inverter connecting portion  31  is connected to the pins  81 U,  81 V, and  81 W of the terminal portion  81 . In  FIG. 27 , conductor portions of the connection fixing portion  38 A are denoted by reference numerals  301 . 
     In contrast, although not shown in the figure, in a case where the pins  81 U and  86 W are connected to each other, the pins  81 V and  86 U are connected to each other, and the pins  81 W and  86 V are connected to each other, instead of connecting the pins  86 U,  86 V, and  86 W to one another, the connection state of the coils  6 U,  6 V, and  6 W is the serial delta connection ( FIG. 14 ). 
     The connection fixing portion  38 B illustrated in  FIG. 28  connects the pins  81 U,  83 U, and  85 U to one another, connects the pins  82 U,  84 U, and  86 U to one another, connects the pins  81 V,  83 V, and  85 V to one another, connects the pins  82 V,  84 V, and  86 V to one another, connects the pins  81 W,  83 W, and  85 W to one another, and connects the pins  82 W,  84 W, and  86 W to one another. Accordingly, the connection state of the coils  6 U,  6 V, and  6 W of each phase is the parallel connection. 
     The connection fixing portion  38 B also connects the pins  86 U,  86 V, and  86 W to one another. Accordingly, the connection state of the coils  6  is the parallel Y connection ( FIG. 22 ). The connection fixing portion  38 B connects the pins  81 U,  81 V, and  81 W of the terminal portion  81  to the inverter  70 . In  FIG. 28 , conductor portions of the connection fixing portion  38 B are denoted by reference numerals  301 . 
     In contrast, although not shown in the figure, in a case where the pins  81 U and  86 W are connected to each other, the pins  81 V and  86 U are connected to each other, and the pins  81 W and  86 V are connected to each other, instead of connecting the pins  86 U,  86 V, and  86 W to one another, the connection state of the coils  6 U,  6 V, and  6 W is the parallel delta connection ( FIG. 24 ). 
       FIG. 29  is a graph showing a relationship between a rotation speed and a motor efficiency of the motor  10  for each of the serial Y connection, the serial delta connection, the parallel Y connection, and the parallel delta connection. 
     M denotes the number of coil elements connected in series or in parallel in each phase of the coils  6 U,  6 V, and  6 W. In the examples illustrated in  FIGS. 26 through 28 , M is 3. In each phase, an inter-terminal voltage when the M coil elements of each phase are connected in series is 1/M of an inter-terminal voltage when the M coil elements of each phase are connected in parallel. 
     Thus, the serial Y connection provides a high motor efficiency in the lowest rotation speed range. The serial delta connection provides a high motor efficiency in the second lowest rotation speed range. The parallel Y connection provides a high motor efficiency in the high rotation speed range. The parallel delta connection provides a high motor efficiency in the highest rotation speed range. 
     Thus, one of the connection fixing portions  38  is selected so that the highest motor efficiency is obtained in accordance with the maximum rotation speed of the compressor  100 . Accordingly, an optimum connection state of the coils  6 U,  6 V, and  6 W can be obtained depending on required specifications of the compressor  100 , and the high operation efficiency can be obtained. 
     As described above, in the third embodiment, the connection state of the coils  6 U,  6 V, and  6 W is changeable among the serial Y connection, the serial delta connection, the parallel Y connection, and the parallel delta connection, after the motor  10  is incorporated in the compressor  100 . Accordingly, it is possible to flexibly cope with various specifications of the compressor  100 , and the operation efficiency of the compressor  100  can be enhanced. 
     In the first through third embodiments, the coils  6 U,  6 V, and  6 W in which three coil elements of each phase are connected in series or in parallel have been described. However, it is also possible that two coil elements or four or more coil elements of each phase are connected in series or in parallel. 
     (Air Conditioner) 
     Next, an air conditioner  400  (also referred to as a refrigeration air conditioning apparatus) to which the compressor  100  of each embodiment is applicable will be described.  FIG. 30  is a diagram illustrating a configuration of the air conditioner  400 . The air conditioner  400  includes the compressor  100  according to the first embodiment, a four-way valve  401  as a switching valve, a condenser  402  for condensing a refrigerant, a decompressor  403  for decompressing the refrigerant, an evaporator  404  for evaporating the refrigerant, and a refrigerant pipe  410  connecting these elements. 
     The compressor  100 , the four-way valve  401 , the condenser  402 , the decompressor  403 , and the evaporator  404  are connected to one another by the refrigerant pipe  410 , and constitute a refrigerant circuit. The air conditioner  400  includes an outdoor fan  405  facing the condenser  402 , and an indoor fan  406  facing the evaporator  404 . 
     An operation of the air conditioner  400  is as follows. The compressor  100  sucks in and compresses a refrigerant, and sends out the compressed refrigerant as a high-temperature and high-pressure refrigerant gas. The four-way valve  401  is configured to switch a flow direction of the refrigerant. In a cooling operation, the four-way valve  401  delivers the refrigerant from the compressor  100  to the condenser  402  as indicated by solid lines in  FIG. 30 . 
     The condenser  402  exchanges heat between the refrigerant sent from the compressor  100  and outdoor air sent from the outdoor fan  405 , condenses the refrigerant, and sends out the refrigerant as a liquid refrigerant. The decompressor  403  expands the liquid refrigerant sent from the condenser  402 , and sends out the refrigerant as a low-temperature and low-pressure liquid refrigerant. 
     The evaporator  404  exchanges heat between indoor air and the low-temperature and low-pressure liquid refrigerant sent from the decompressor  403 , evaporates (vaporizes) the refrigerant, and sends out the refrigerant as a refrigerant gas. Air from which heat is taken in the evaporator  404  is supplied by the indoor fan  406  into a room that is a space to be air-conditioned. 
     In a heating operation, the four-way valve  401  delivers the refrigerant from the compressor  100  to the evaporator  404 . In this case, the evaporator  404  functions as a condenser, and the condenser  402  functions as an evaporator. 
     As described in the first embodiment, the compressor  100  of the air conditioner  400  is configured so that the connection state of the coils  6  of the motor  10  is changeable. Thus, output characteristics of the compressor  100  can be flexibly changed depending on specifications of the air conditioner  400 . As a result, the operation efficiency of the air conditioner  400  can be enhanced. 
     Instead of the compressor of the first embodiment, the compressor of the second or third embodiment may be used. Components except for the compressor  100  in the air conditioner  400  are not limited to the example described above. 
     Although the preferred embodiments of the present invention have been specifically described above, the present invention is not limited to these embodiments, and various improvements and modifications may be made without departing from the scope of the invention.