JP2016085005A - Refrigeration cycle device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To perform a highly efficient operation in a wide rotational frequency range, and to reduce power consumption in a long-term view.SOLUTION: A refrigeration cycle device mounts a compressor including: a stator in which a plurality of pieces of coil units 23U, 23V, 23W including a plurality of pieces of coils 231, 232 are arranged; and a rotor in which a plurality of poles are formed. It also includes a control unit 36 which switches a connection state of the coils 231, 232 included in each of the coil units 23U, 23V, 23W, and the control unit 36 switches the connection state of the coil units 23U, 23V, 23W according to an operation condition.SELECTED DRAWING: Figure 4

Description

  The present invention relates to a refrigeration cycle apparatus.

  In recent years, many refrigeration cycle apparatuses are capable of variably adjusting the refrigeration capacity by adjusting the rotational speed of the compressor. That is, the refrigeration capacity of the refrigeration cycle apparatus can be increased by operating the compressor at a high speed (rated operation). An electric motor is usually incorporated in the compressor, and the rotation speed is electrically controlled. In addition, the refrigeration capacity can be adjusted as necessary by performing an intermediate operation with a reduced number of rotations of the electric motor (an operation in which the capacity is about half of the rating).

  For example, assume that the refrigeration cycle apparatus is used in an air conditioner. When cooling or heating is performed immediately after turning on the air conditioner or the like, the compressor is rated to increase the refrigeration capacity of the refrigeration cycle apparatus and increase the cooling or heating output. In addition, when the temperature reaches a certain temperature and cooling or heating at a temperature maintaining level is sufficient, the compressor is operated in an intermediate state, the refrigeration capacity of the refrigeration cycle apparatus is kept low, and the room temperature is stabilized with low power consumption.

  Most of the power consumption of the refrigeration cycle apparatus is consumed by the compressor. And increasing the efficiency of the compressor (the electric motor included in the compressor) leads to a reduction in power consumption. The characteristics of the motor vary depending on the number of windings of the coil, and the number of rotations with the highest efficiency is determined by the number of windings. That is, it has been difficult to increase the efficiency in the entire range from the low rotation to the high rotation with the electric motor having the conventional configuration.

  In view of this, there has been proposed an electric motor that can be operated in a highly efficient state even when the rotational speed changes, such as the winding switching type rotating electric machine described in Japanese Patent Application Laid-Open No. 6-205573. In this winding-switching type rotating electrical machine, the efficiency of high-speed operation (rated operation) and low-speed operation (intermediate operation) is changed by switching the coil that supplies power according to the motor speed and changing the number of coils. Is suppressed.

JP-A-6-205573

  The winding switching type rotating electrical machine described in Japanese Patent Application Laid-Open No. 6-205573 is used by switching between a high rotation side coil and a low rotation side coil. An air conditioner including a refrigeration cycle apparatus is configured to perform cooling for cooling a room and heating for heating a room using a compressor. In the air conditioner, since the necessary refrigeration capacity varies depending on the difference between the cooling operation and the heating operation, the difference in the outside air temperature, and the like, it is necessary to finely control the rotation speed of the compressor. Even if the coil-switching type rotating electrical machine is used as an electric motor for a compressor that needs to control the rotational speed in detail, the power consumption cannot always be reduced by long-term operation.

  In addition, when the coil is switched and used like the winding switching type rotating electrical machine, if the relative turn ratio fluctuation is large before and after the switching, a large current is instantaneously generated when the coil is switched, This could cause failure or damage to the rotating electrical machine (electric motor) itself or the control circuit, and to shorten the life.

  Accordingly, an object of the present invention is to provide a refrigeration cycle apparatus that can increase the time during which high-efficiency operation is performed, has a long life, and has little waste.

  To achieve the above object, the present invention provides a refrigeration cycle apparatus equipped with a compressor including a stator in which a plurality of coil units including a plurality of coils are arranged, and a rotor in which a plurality of poles are formed. A control unit that switches a connection state of coils included in each of the plurality of coil units, and the control unit switches a connection state of the plurality of coil units according to an operating condition. Features.

  According to this configuration, the compressor can be driven efficiently under many operating conditions by switching the coil unit. As a result, the time for high-efficiency operation can be extended and energy consumption can be reduced over a long period of time.

  The said structure WHEREIN: The said control part switches the connection state of these coil units based on at least one of the rotation speed or torque of the said compressor. With this configuration, it is possible to finely adjust the switching of the connection state of the coil unit, and it is possible to drive with high efficiency.

  The said structure WHEREIN: The said control part switches the connection state of the said coil unit in the state which reduced the rotation speed of the said compressor temporarily. According to this configuration, the compressor has a simple configuration and suppresses the generation of an instantaneous large current when switching the connection state of the coil unit. Since an instantaneous large current does not flow, it is possible to prevent the circuit and the motor from being broken or damaged, and to extend the service life.

  In the above configuration, each of the plurality of coil units may be provided with a preload, and the connection state of the coil unit may be switched after the power is supplied to the preload. According to this structure, generation | occurrence | production of the instantaneous large current when switching the connection state of a coil unit is suppressed. Since an instantaneous large current does not flow, it is possible to prevent the circuit and the motor from being broken or damaged, and to extend the service life. In addition, the preload can mention what has the impedance which can suppress an instantaneous large current reliably, when switching a coil unit.

  In the above configuration, the coil unit includes two coils having the same configuration, and a first state in which two coil units connected in series are connected in a star connection, and two coils are connected in series. A second state in which the coil units are connected by a delta connection, a third state in which a coil unit in which two coils are connected in parallel are connected in a star connection, and a coil unit in which two coils are connected in parallel are a delta connection Can be switched to the connected fourth state.

  According to the present invention, it is possible to provide a refrigeration cycle apparatus that can perform high-efficiency operation under a wide range of operating conditions, has a long life, and has little waste.

It is the schematic of an air conditioner. It is the schematic of an example of the refrigerating-cycle apparatus concerning this invention. It is sectional drawing cut | disconnected by the surface perpendicular | vertical to the axis | shaft of the electric motor arrange | positioned at the compressor concerning this invention. It is a wiring diagram of the electric motor provided in the compressor. It is the wiring diagram which star-connected the coil unit which connected the 1st coil part and the 2nd coil part in series. It is the wiring diagram which connected the coil unit which connected the 1st coil part and the 2nd coil part in series with delta. It is the wiring diagram which star-connected the coil unit which connected the 1st coil part and the 2nd coil part in parallel. It is the wiring diagram which connected the coil unit which connected the 1st coil part and the 2nd coil part in parallel delta connection. It is a table | surface which compares the operating condition of an air conditioner, the driving | running state of a refrigerating-cycle apparatus, the rotational speed of an electric motor, and the connection state of a coil unit. It is a wiring diagram which shows the intermediate state in the middle of the electric motor switching. It is a wiring diagram which shows the intermediate state in the middle of the electric motor switching. It is a graph which shows the relationship between the rotation speed when a motor is driven in the connection state of a different coil, and motor efficiency. It is a circuit diagram of the electric motor with which the compressor of the refrigerating cycle device concerning the present invention was equipped.

The present invention will be described below with reference to the drawings.
(First embodiment)
FIG. 1 is a schematic diagram of an air conditioner, and FIG. 2 is a schematic diagram of an example of a refrigeration cycle apparatus according to the present invention. As shown in FIG. 1, the air conditioner Ac includes an indoor unit IM installed in the interior (wall) of the living room Rm and an outdoor unit OM installed outside the living room Rm. Note that openings such as doors and windows are omitted when air conditioning is performed, and may be considered integral with walls, ceilings, and the like. The air conditioner A performs air conditioning in the room Rm by taking the air in the room Rm into the indoor unit IM and discharging the conditioned air.

  As shown in FIG. 2, the refrigeration cycle apparatus Rc includes devices such as a compressor 11, a four-way valve 12, an outdoor heat exchanger 13, a decompression unit 14, and an indoor heat exchanger 15. These devices are connected by a refrigerant pipe, and a refrigerant is sealed inside, thereby forming a known refrigerant circuit.

  As shown in FIG. 2, in the refrigeration cycle apparatus Rc, the compressor 11, the four-way valve 12, the outdoor heat exchanger 13, the decompression unit 14, the outdoor fan 131, and the accumulator 16 are arranged in the outdoor unit OM, and indoor heat exchange is performed. The unit 15 and the indoor fan 151 are arranged in the indoor unit IM. Note that the decompression unit 14 may be provided not in the outdoor unit OM but in the indoor unit IM.

  The compressor 11 is a device that compresses the refrigerant. The compressor 11 is connected to an outflow pipe Po through which the refrigerant flows out and an inflow pipe Pi through which the refrigerant flows. The outflow pipe Po and the inflow pipe Pi are both connected to the four-way valve 12. An accumulator 16 is attached to the inflow pipe through which the refrigerant flows into the compressor 11. The refrigerant returning to the compressor 11 is in a state where the gas phase and the liquid phase are mixed. The refrigerant is separated into liquid and gas by passing through the accumulator 16. Then, a gaseous refrigerant flows into the compressor 11.

  The four-way valve 12 changes the flow direction of the refrigerant circuit. That is, the connection destination (outdoor heat exchanger 13 or indoor heat exchanger 15) between the outflow pipe Po and the inflow pipe Pi is switched. For example, when the four-way valve 12 connects the outflow pipe Po and the outdoor heat exchanger 13 and connects the inflow pipe Pi and the indoor heat exchanger 15, the air conditioner Ac performs a cooling operation for cooling the interior of the room Rm. Further, when the four-way valve 12 is reversely connected, a heating operation for heating the room Rm is performed.

  The decompression unit 14 reduces the pressure of the refrigerant, and an expansion valve is employed here. The outdoor heat exchanger 13 and the indoor heat exchanger 15 are for exchanging heat between the air outside and inside the living room Rm and the refrigerant, for example, fins for increasing the cross-sectional area of the refrigerant pipe Can be mentioned. It is possible to increase the efficiency of heat exchange by blowing air to the fins and forcibly sending air. Therefore, in the refrigeration cycle apparatus A, the outdoor fan 131 is provided in the vicinity of the outdoor heat exchanger 13, the indoor fan 151 is provided in the vicinity of the indoor heat exchanger 15, and air is blown to each heat exchanger, so that the refrigerant and the air Heat exchange efficiently.

  The compressor 11 compresses the refrigerant by an electric motor arranged inside. Next, the electric motor A included in the compressor 11 will be described with reference to the drawings. FIG. 3 is a cross-sectional view taken along a plane perpendicular to the shaft of the electric motor disposed in the compressor according to the present invention, and FIG. 4 is a wiring diagram of the electric motor provided in the compressor.

  The electric motor A is a three-phase DC brushless motor. In the electric motor A, the stator (stator) 20 includes nine slots 21. A rotor (rotor) 22 is disposed inside the stator 20. An output shaft 221 is integrally fixed to the center of the rotor 22. A permanent magnet (not shown) is disposed on the rotor 22. As the rotor 22, for example, a rotor provided with eight permanent magnets (having eight poles formed) can be used.

  A conductive wire is wound around each slot 21 of the electric motor A, and each slot 21 constitutes a coil (field). The coil units 23 are supplied with AC power U-phase power, V-phase power, and W-phase power, which are 120 ° out of phase. Therefore, in the following description, the coils to which the electric power of each of the three phases is applied are divided into three systems of a U-phase coil unit 23U, a V-phase coil unit 23V, and a W-phase coil unit 23W. The electric motor A supplies electric power having phases corresponding to the U-phase coil unit 23U, the V-phase coil unit 23V, and the W-phase coil unit 23W, so that the rotor 20 rotates, that is, a rotational force is generated. The generated rotational force is taken out of the electric motor A through an output shaft 21 fixed integrally with the rotor 20.

  As shown in FIG. 4, the U-phase coil unit 23 </ b> U, the V-phase coil unit 23 </ b> V, and the W-phase coil unit 23 </ b> W include a first coil part 231 and a second coil part 232. The U-phase coil unit 23U, the V-phase coil unit 23V, and the W-phase coil unit 23W are provided with preliminary loads Z1, Z2, and Z3 separately from the first coil portion 231 and the second coil portion 232, respectively. In addition, since alternating current is supplied to the motor A, as the preloads Z1, Z2, and Z3, in addition to normal resistance, inductive (coil), capacitive (capacitor), or these A combination is used.

  Furthermore, the electric motor A changes the combination of the connections of the first coil portion 231 and the second coil portion 232 of each of the U-phase coil unit 23U, the V-phase coil unit 23V, and the W-phase coil unit 23W, and supplies power to each coil unit. Is provided. Note that the U-phase coil unit 23U, the V-phase coil unit 23V, and the W-phase coil unit 23W have the same configuration.

  The drive circuit 3 includes a motor controller 31, switching elements 321, 322, 323, 331 to 334, 341 to 344, 351 to 354, and a control unit 36. The motor controller 31 is a driver circuit that supplies power to each of the U-phase coil unit 23U, the V-phase coil unit 23V, and the W-phase coil unit 23W. The motor controller 31 converts electric power from a power source (not shown) into electric power (voltage waveform, frequency, period, etc.) suitable for driving the electric motor A. The motor controller 31 includes a U terminal 311 that outputs U-phase power, a V terminal 312 that outputs V-phase power, and a W terminal 313 that outputs W-phase power.

  Next, the switching element will be described. Switching elements 321, 322, and 323 are connected to the U-phase coil unit 23 U, the V-phase coil unit 23 V, and the W-phase coil unit 23 W on the opposite side to the U-terminal 311, V-terminal 312, and W-terminal 313, respectively. Is attached. Switching elements 321, 322, and 323 are switching elements for switching the wiring. When switching elements 321, 322, and 323 are connected to the A contact, U-phase coil unit 23U, V-phase coil unit 23V, and W-phase coil unit 23W are connected by star connection. Conversely, when switching elements 321, 322, and 323 are connected to the B contact, U-phase coil unit 23U, V-phase coil unit 23V, and W-phase coil unit 23W are connected by delta connection.

  That is, the switching elements 321, 322, and 323 are switches for switching the U-phase coil unit 23U, the V-phase coil unit 23V, and the W-phase coil unit 23W between star connection and delta connection. Therefore, the control unit 36 controls the switching elements 321, 322, and 323 synchronously. For example, when the star connection is made, the control unit 36 connects the switching elements 321, 322, and 323 to the respective A contacts at the same timing.

  Switching elements 331, 332, 333, and 334 are provided in U-phase coil unit 23U. The switching element 331 and the switching element 334 are changeover switches for switching the connection direction. The switching elements 332 and 333 are switches that switch ON or OFF (circuit connection or disconnection).

  The switching element 331 and the switching element 332 are switches that connect the first coil part 231 and the second coil part 232 by either a serial or parallel connection method. The first coil portion 231 and the second coil portion 232 can be connected in series by connecting the switching element 331 to the A contact and turning off the switching element 332. Further, the first coil part 231 and the second coil part 232 can be connected in parallel by connecting the switching element 331 to the B contact and turning on the switching element 332.

  The switching element 333 is an ON / OFF switch that connects or disconnects a circuit that supplies power to the preliminary load Z1. The switching element 334 is a change-over switch that switches and connects the preliminary load Z1 to a star connection wiring or a delta contact wiring.

  Switching elements 341, 342, 343, and 344 are switching elements for switching the connection of the V-phase coil unit 23V. Switching elements 351, 352, 353, and 354 are switching elements for switching the connection of the V-phase coil unit 23V. Switching elements 341 and 351 are switching elements 331, switching elements 342 and 352 are switching elements 332, switching elements 343 and 353 are switching elements 333, and switching elements 344 and 354 are switching elements corresponding to the switching elements 334, respectively. . Therefore, each switching element provided in the V-phase coil unit 23V and the W-phase coil unit 23W performs the same configuration and operation as the switching element of the corresponding U-phase coil unit 23U.

  Examples of the switching elements 321, 322, 323, 331 to 334, 341 to 344, and 351 to 354 include, but are not limited to, elements such as IGBTs and power MOSFETs and combinations thereof.

  Next, the electric motor A provided in the compressor according to the present invention will be described. The electric motor A has a configuration in which a three-phase coil unit can be used by switching between a star connection and a delta connection. In the electric motor A according to the present invention, the first coil portion 231 and the second coil unit 232 of each coil unit can be switched in series or in parallel. Hereinafter, the state of the electric motor when the switching element is switched will be described with reference to the drawings.

  5 to 8 are wiring diagrams when the coil unit in which the first coil portion and the second coil portion are connected in series or in parallel is star-connected or delta-connected. In addition, since the corresponding switching element in the electric motor A is driven synchronously, in the following description, the switching element included in the U-phase coil unit 23U will be mainly described, and the V-phase coil unit 23V and the W-phase will be described. The description will be made assuming that the switching elements of the coil unit 23W simultaneously perform the same operation. In the following description, in the wiring diagram, a circuit to which electric power is supplied (current flows or voltage is applied) is indicated by a thick line.

  FIG. 5 is a wiring diagram in which a coil unit in which a first coil portion and a second coil portion are connected in series is star-connected. As shown in FIG. 5, the control unit 36 connects the switching element 331 of the U-phase coil unit 23 </ b> U to the A contact and turns off the switching element 332, so that the first coil unit 231, the second coil unit 232, Are connected in series. Similarly, the V-phase coil unit 23V and the W-phase coil unit 23W operate the corresponding switching elements, so that the first coil portion 231 and the second coil portion 232 of each coil unit are connected in series. Then, the switching elements 321, 322, and 323 are connected to the A contact. Accordingly, the electric motor A is in a series star state in which a coil unit in which the first coil portion 231 and the second coil portion 232 are connected in series is star-connected.

  FIG. 6 is a wiring diagram in which a coil unit in which a first coil portion and a second coil portion are connected in series is delta-connected. As shown in FIG. 6, by switching the switching elements 321, 322, and 323 to the B contact from the state of FIG. 5, the electric motor A has a coil unit in which the first coil part 231 and the second coil part 232 are connected in series. It becomes a series delta state with delta connection.

  FIG. 7 is a wiring diagram in which a coil unit in which a first coil portion and a second coil portion are connected in parallel is star-connected. As shown in FIG. 7, the control unit 36 connects the switching element 331 of the U-phase coil unit 23 </ b> U to the B contact and turns on the switching element 332, whereby the first coil unit 231, the second coil unit 232, Are connected in parallel. Similarly, the V-phase coil unit 23V and the W-phase coil unit 23W operate the corresponding switching elements, so that the first coil portion 231 and the second coil portion 232 of each coil unit are connected in parallel. Then, the switching elements 321, 322, and 323 are connected to the A contact. Thereby, it will be in the parallel star state which star-connected the coil unit which connected the 1st coil part 231 and the 2nd coil part 232 in parallel.

  FIG. 8 is a wiring diagram in which a coil unit in which a first coil portion and a second coil portion are connected in parallel is delta-connected. As shown in FIG. 8, by switching the switching elements 321, 322, and 323 to the B contact from the state of FIG. 7, the electric motor A has a coil unit in which the first coil part 231 and the second coil part 232 are connected in parallel. A delta-connected parallel delta state is established.

  Next, driving of the refrigeration cycle apparatus Rc according to the present invention will be described. In the refrigeration cycle apparatus Rc, the refrigerating capacity (for example, the cooling capacity or the heating capacity in the air conditioner Ac) is adjusted by adjusting the rotational speed of the compressor 11, that is, the rotational speed of the electric motor A.

  In general, the electric motor A which is a three-phase brushless motor has a high efficiency at a low rotation (a maximum efficiency is reached) when the number of windings is large, and decreases at a high rotation. On the other hand, when the number of windings is small, the efficiency at low rotation is low, but the efficiency at high rotation is high (the maximum efficiency is reached).

  As described above, the electric motor A is configured to change the relative number of windings by switching the switching element. For example, relative to the number of windings in the series star state, the relative turns ratio is 1 / √3 in the series delta state, 1/2 in the parallel star state, and 1 in the parallel delta state. / 2√3. That is, in the electric motor A, the same effect as when the number of windings is changed by switching the state can be obtained.

  By utilizing this, in the refrigeration cycle apparatus Rc according to the present invention, the control for switching the winding ratio (coil connection state) of the electric motor A in accordance with the operating condition (required output) of the refrigeration cycle apparatus Rc. Has been done. Hereinafter, the refrigeration cycle apparatus Rc used in the air conditioner Ac will be described as an example. It is assumed that the air conditioner Ac is used as a cooling device.

  In the refrigeration cycle apparatus Rc used in the air conditioner Ac, the required output (operating state) varies depending on the operating state of the air conditioner Ac. FIG. 9 shows a table comparing the operating conditions of the air conditioner, the operating state of the refrigeration cycle apparatus, the rotational speed of the electric motor, and the connection state of the coil unit.

  When the power of the air conditioner Ac is turned on (when operation is started), the refrigeration cycle apparatus Rc starts rotating the compressor 11 (set to a start state). When the compressor 11 is in the start state, the electric motor A operates at an extremely low rotation. Therefore, when the refrigeration cycle apparatus Rc is in the start state, the control unit 36 controls the switching elements so as to be in a series star state with the largest number of windings (relative winding number ratio). Accordingly, a smooth operation can be performed at the start of operation, and an operation can be performed efficiently.

  In the air conditioner A, when the indoor temperature is close to the set temperature, the refrigeration cycle apparatus Rc can perform indoor air conditioning with a small output. The air conditioner A is also affected by the outside air temperature. For example, when the temperature difference between the room and the outside is low, such as at night, and the room temperature is close to the set temperature (night operation), the refrigeration cycle apparatus Rc can maintain the room temperature with low output ( Low output state). When the refrigeration cycle apparatus Rc is in a low output state, the compressor 11 (electric motor A) is driven at a low rotation. When the refrigeration cycle apparatus Rc is in the low output state, the control unit 36 controls the switching element so that the number of windings (relative winding number ratio) is the second most in the series delta state.

  On the other hand, when the temperature difference between the room and the outside is high as in the daytime (normal operation during the daytime), it is difficult to maintain the room temperature unless there is a certain output from the refrigeration cycle apparatus Rc. Therefore, in the refrigeration cycle apparatus Rc, the room temperature is maintained (the medium output state is set) by driving with a constant output (intermediate output). When the refrigeration cycle apparatus Rc is in the medium output state, the compressor 11 (electric motor A) is driven at medium speed rotation. When the refrigeration cycle apparatus Rc is in the medium output state, the control unit 36 controls the switching elements so that the number of windings (relative winding number ratio) is the second smallest and the parallel star state is achieved.

  Furthermore, when the temperature difference between the indoor air and the outside in the daytime is high and the room temperature is far from the set temperature (rapid cooling operation), the refrigeration cycle apparatus Rc is required to have a high output (high output). State). When the refrigeration cycle apparatus Rc is in a high output state, the compressor 11 is driven at a high speed. When the refrigeration cycle apparatus Rc is in the high output state, the control unit 36 controls the switching element so that the parallel delta state is achieved with the smallest number of windings (relative winding number ratio).

  In addition, by switching the coil state based on the operation state of the refrigeration cycle apparatus Rc, the electric motor A (compressor 11) can be driven in the most efficient state in each operation state. Thereby, refrigeration cycle apparatus Rc becomes efficient in a wide driving | running state.

  The start state, the low output state, the medium output state, and the high output state are determined based on the number of turns of the coil of the electric motor A and the relative turn ratio so that the efficiency is improved in each state. It is preferable.

  On the other hand, when the connection state of the coil is switched while the electric motor A is being driven, a large current may instantaneously flow at the time of switching. The electric motor A of the present invention allows a current to flow through the preliminary load at the time of switching, and suppresses a large current from flowing instantaneously. Hereinafter, switching of the switching element will be described. In addition, although the case where it switches from a serial star state to a serial delta state is demonstrated here, the same switching is performed other than this. 10 and 11 are wiring diagrams showing an intermediate state in the middle of switching of the electric motor.

  When the compressor 11 of the refrigeration cycle apparatus Rc is in an extremely low rotation state, the electric motor A is in a series star state, and each switching element is in the state shown in FIG. That is, the control unit 36 connects the switching element 331 of the U-phase coil unit 23U to the A contact and connects the switching element 321 to the A contact. Control unit 36 also switches the corresponding switching elements of V-phase coil unit 23V and W-phase coil unit 23W in synchronization.

  And refrigeration cycle apparatus Rc is adjusting the output with the number of rotations. Therefore, when the operation of increasing the output is performed, the rotational speed of the compressor 11, that is, the electric motor A also increases. And when refrigeration cycle apparatus Rc will be in a low rotation state, efficiency will fall in a serial star state. Therefore, in order to switch to the series delta state, the control unit 36 connects the switching element 334 to the A contact and turns on the switching element 333 (see FIG. 10).

  By connecting in this way, the preliminary load Z1 is connected in parallel with a coil in which the first coil portion 231 and the second coil portion 232 are connected in series. The U-phase coil unit 23U, the V-phase coil unit 23V, and the W-phase coil unit 23W are star-connected in a state where the preliminary loads Z1, Z2, and Z3 are connected in parallel. In addition, since the connection of the preliminary loads Z1, Z2, and Z3 is controlled by the switching elements 334, 344, and 354, the connection state can be switched independently of the coil unit.

  Then, the control unit 36 switches the switching elements 321, 322, and 323 from the A contact to the B contact. At the moment when the contacts of the switching elements 321, 322, and 323 are switched, the first coil portion 231 and the second coil portion 232 are disconnected. On the other hand, the preliminary loads Z1, Z2, and Z3 are in a star-connected state. When the switching elements 321, 322, and 323 are connected to the B contact (see FIG. 11), the preliminary loads Z 1, Z 2, and Z 3 maintain the star state, and the first coil portion 231 and the second coil portion 232 The series coil units 23U, 23V, and 23W are delta-connected.

  In a state where current flows through the preliminary loads Z1, Z2, and Z3, the wiring state in FIG. 10 is switched to the wiring state in FIG. Therefore, instantaneous generation of a large current due to switching of the switching elements 321, 322, and 323 can be suppressed.

  And the control part 36 stops supply of the electric power to the preliminary | backup load Z1 by turning off the switching element 333. FIG. The controller 36 simultaneously turns off the switching elements 343 and 353 in the V-phase coil unit 23V and the W-phase coil unit 23W (see FIG. 7).

  When switching from the wiring state of FIG. 10 to the wiring state of FIG. 11, the preliminary loads Z1, Z2, and Z3 are switched while maintaining the star connection state. That is, in the electric motor A according to the present invention, when the wiring of the coil unit is switched, a pseudo circuit is configured using the preliminary load, and the preliminary load is disconnected after switching the circuit. When switching, keep a constant current flowing through the preload. As a result, the voltage is unlikely to change abruptly at the time of switching, so that an instantaneous large current can be suppressed.

  As described above, when switching from the series star state to the series delta state, it is possible to suppress an instantaneous large current from being generated in the circuit of the electric motor A by switching while supplying a current to the preliminary load.

  As described above, the refrigeration cycle apparatus Rc can maintain the efficiency of the compressor 11 (the electric motor A) high in many states by switching the coil connection state according to the operation state. Thereby, the power consumption when using it intermittently or continuously over a long period of time can be suppressed. In addition, when switching the coil, it is performed after the intermediate state using the preload, so it is difficult to generate a momentary large current, and the circuit may be damaged or the life may be shortened. Can be suppressed.

(Second Embodiment)
Another example of the refrigeration cycle apparatus according to the present invention will be described with reference to the drawings. The refrigeration cycle apparatus Rc according to the present invention has the same basic configuration as the refrigeration cycle apparatus Rc of the first embodiment, except that the control for switching the coil state is different. Therefore, detailed description of the refrigeration cycle apparatus Rc is omitted.

  In the first embodiment, the electric motor A is driven corresponding to the operating state of the refrigeration cycle apparatus Rc. Therefore, the state of the coil can be easily and appropriately switched. In the case of such a configuration, it is possible to increase the efficiency to some extent in each operation state. On the other hand, depending on the refrigeration capacity required for the refrigeration cycle apparatus Rc, an operation with an output during each operation state may be required.

  A procedure for determining the timing for switching the coil connection state will be described. FIG. 12 is a graph showing the relationship between the rotational speed and the motor efficiency when the motor is driven with different coil connections. In the graph shown in FIG. 12, the vertical axis represents motor efficiency, and the horizontal axis represents motor rotation speed. In the graph shown in FIG. 12, the broken line L1 is the series star state, the solid line L2 is the series delta state, the alternate long and short dash line L3 is the parallel star state, and the thick line L4 is the motor efficiency and rotational speed when the coil units are connected in the parallel delta state. Is shown.

  As shown in FIG. 12, in the refrigeration cycle apparatus Rc, from the start of operation to the first rotation speed R1, the broken line L1 has a higher motor efficiency than the solid line L2. That is, in the region below the first rotation speed R1, the compressor 11 (electric motor A) is more efficient in the coil unit connection state in the series star state than in the series delta state. Therefore, the controller 36 is driven in a series star state when the rotation speed of the electric motor A is less than the first rotation speed R1, and switches to the series delta state when the rotation speed becomes equal to or higher than the first rotation speed R1.

  Also, as shown in FIG. 12, the solid line L2 is higher than the one-dot chain line L3 up to the second rotational speed R2. That is, in the region from the first rotation speed R1 to the second rotation speed R2, the compressor 11 (electric motor A) is more efficient in the connection state of the coil unit in the series star state than in the series delta state. Therefore, the control unit 36 drives in a series delta state when the rotation speed of the electric motor A is equal to or higher than the first rotation speed R1 and lower than the second rotation speed R2.

  Similarly, the upper and lower sides of the motor efficiency are switched, in other words, the connection state of the coil unit is switched at the number of rotations at which the graph of the motor efficiency intersects. Thus, it is possible to perform more detailed control by detecting the motor efficiency for each connection state of the coil unit and switching the connection state of the coil unit at the number of rotations at which the magnitude of the motor efficiency is switched.

  In this embodiment, the switching rotational speed is stored, and the connection state of the coil unit is switched every time the rotational speed is reached. However, the present invention is not limited to this. For example, the motor efficiency at the time when the connection state of the coil unit is switched is stored, and when the motor efficiency of the motor A in operation becomes the stored motor efficiency, the connection state of the coil unit is switched. Good.

  Further, in the case of the configuration for detecting the motor efficiency during operation of the motor A, the relationship between the rotational speed and the motor efficiency is graphed as shown in FIG. 12, and the graph is sequentially updated so that the motor efficiency when switching is performed. The value of may be updated. By doing in this way, even if dispersion | variation in a coil part, a switching element, etc. arises, it is possible to drive the electric motor A, ie, the compressor 11, with high efficiency. It is also possible to absorb variations due to changes in refrigerant and piping.

  In the present embodiment, the connection state of the coil unit is switched using the relationship between the rotation speed of the motor A and the motor efficiency. However, the present invention is not limited to this. For example, the rotation speed of the motor A and (Or) You may make it switch the connection state of a coil unit using the relationship between a torque and motor efficiency. For example, when the rotational speed is suddenly increased, the efficiency may increase as a result of ignoring the motor efficiency and increasing the rotational speed at a stretch with high torque. In such a case, the connection state of the coil unit with high torque and high motor efficiency to some extent may be selected. Further, since the current increases in the case of high torque, a connection state with a smaller electrical resistance may be selected in order to reduce copper loss.

  Other features are the same as in the first embodiment.

(Third embodiment)
Another example of the refrigeration cycle apparatus according to the present invention will be described with reference to the drawings. FIG. 13 is a circuit diagram of an electric motor provided with a compressor of the refrigeration cycle apparatus according to the present invention. The electric motor B shown in FIG. 13 has a configuration in which the preliminary loads Z1, Z2, and Z3 and the switching elements 333, 334, 343, 344, 353, and 354 are omitted from the electric motor A.

  Similarly to the electric motor A, the electric motor B can be combined with the connection state (series or parallel) of the first coil portion 231 and the second coil portion 232 and the connection state of the coil unit (star connection and delta connection). That is, the electric motor B can be switched to a series star state, a series delta state, a parallel star state, and a parallel delta state.

  When the connection state of the coil unit is switched while the operation of the electric motor B is continued, a large current is instantaneously generated when the connection state of the coil unit is switched. It is known that this large current is generated when switching is performed with the motor B rotating at a high speed. Therefore, when the connection state of the coil unit is switched, the rotational speed is once lowered, and after switching the connection state of the coil unit, the rotational speed is increased to the switching timing. In this way, since the rotational speed is reduced, the efficiency may be somewhat reduced. However, a preliminary load and a switching element for switching are unnecessary, and the compressor 11 including the electric motor B, that is, a refrigeration It is possible to simplify the configuration of the cycle device Rc.

  And since the structure of the compressor 11 containing the electric motor B is simple, it is also possible to reduce the effort (cost) concerning maintenance inspection.

  Other features are the same as those in the first and second embodiments.

  In each above-mentioned embodiment, although what has connected the 1st coil part and the 2nd coil part of the coil unit of each phase in series or in parallel is mentioned, it is not limited to this. By appropriately arranging the switching elements, it is possible to adopt a configuration in which one of the first coil portion and the second coil portion is used. Moreover, although it is assumed that the first coil portion and the second coil portion have the same configuration (number of turns, impedance), it is not limited to this.

  In each of the above-described embodiments, the coil unit of each phase has been described as an example including two coils of the first coil portion and the second coil portion, but is not limited thereto. For example, the structure provided with three or more coil parts may be sufficient. Further, it is assumed that the coil unit is composed of one coil portion, and the configuration using a preload when switching the coil unit from the star connection to the delta connection can obtain the same effect as the present invention.

  Moreover, although the thing with fixed impedance is used as a preliminary | backup load, a variable thing may be utilized, the preliminary | backup load to be used is prepared using a plurality of preliminary | backup loads and using a switching element. It may be used so as to be switched.

  In the above-described embodiment, the refrigeration cycle apparatus is used as an air conditioner, but is not limited to this, for example, heat exchange over a long period of time such as a refrigerator, a drying washing machine, a water heater, etc. It can be used as a heat exchange device for a device whose operating conditions vary.

  As mentioned above, although embodiment of this invention was described, this invention is not limited to this content. The embodiments of the present invention can be variously modified without departing from the spirit of the invention.

Rc Refrigeration cycle apparatus 11 Compressor 12 Four-way valve 13 Outdoor heat exchanger 131 Outdoor fan 14 Decompression unit 15 Indoor heat exchanger 151 Indoor fan 16 Accumulator A Electric motor 20 Stator 21 Slot 22 Rotor 221 Output shaft 23U U-phase coil unit 23V V-phase Coil unit 23W W phase coil unit 231 1st coil part 232 2nd coil part 31 Motor controller 311 U terminal 312 V terminal 313 W terminals 321, 322, 323 Switching element 331, 332, 333, 334, 335 Switching element (U phase) Coil unit)
341, 342, 343, 344, 345 Switching element (V phase coil unit)
351, 352, 353, 354, 355 Switching element (W-phase coil unit)
36 Control unit

Claims (5)

A refrigeration cycle apparatus equipped with a compressor including a stator in which a plurality of coil units including a plurality of coils are arranged and a rotor in which a plurality of poles are formed,
A control unit that switches a connection state of coils included in each of the plurality of coil units;
The said control part switches the connection state of these coil units according to an operating condition, The refrigerating-cycle apparatus characterized by the above-mentioned.   2. The refrigeration cycle apparatus according to claim 1, wherein the control unit switches a connection state of the plurality of coil units based on at least one of a rotation speed and a torque of the compressor.   3. The refrigeration cycle apparatus according to claim 1, wherein the control unit switches a connection state of the coil unit in a state where the rotation speed of the compressor is temporarily lowered. Each of the plurality of coil units is provided with a preload,
The refrigeration cycle apparatus according to claim 1 or 2, wherein the connection state of the coil unit is switched after connection is made so as to supply power to the preliminary load. The coil unit includes two coils having the same configuration,
A first state in which a coil unit in which two coils are connected in series is connected in a star connection;
A second state in which two coil units connected in series are connected by a delta connection;
A third state in which a coil unit in which two coils are connected in parallel is connected by star connection;
The refrigeration cycle apparatus according to any one of claims 1 to 4, wherein the refrigeration cycle apparatus can be switched to a fourth state in which a coil unit in which two coils are connected in parallel is connected by a delta connection.

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