Refrigeration and air conditioning apparatus

Abstract

The present application relates to a refrigeration and air conditioning apparatus that performs a defrosting operation. The refrigeration and air conditioning apparatus is provided with: a refrigerant circuit that is formed by connecting a compressor, a first heat exchanger, a throttling device, a second heat exchanger, and a four-way valve by pipes, for circulating a refrigerant; a temperature sensor that measures the temperature of the compressor; and a heat generation control unit that, in a defrosting operation of the first heat exchanger, causes the temperature of the compressor to rise if a decrease in the measured value of the temperature sensor is detected.

Description

Technical Field

[0001] This disclosure relates to a refrigeration and air conditioning unit that performs defrosting operation. Background Technology

[0002] In refrigeration and air conditioning systems, to restore the reduced air conditioning capacity that occurs when frost forms on the heat exchanger on the heat source side, a defrosting operation is performed during heating operation to heat the heat exchanger on the heat source side and melt the frost. During the defrosting operation, heat energy is consumed in the heat exchanger on the heat source side to heat it.

[0003] It is known that during defrost operation, liquid refrigerant can be drawn into the compressor, resulting in liquid refrigerant backflow. Patent Document 1 discloses a method for heating the refrigerant using an inverter to prevent liquid refrigerant backflow during defrost operation. Additionally, a method for heating the inverter of a smart power module to suppress thermal shock during defrost operation is also known.

[0004] Patent Document 1: International Publication No. 2020 / 008620

[0005] During defrost operation, heat energy is consumed to heat the heat exchanger on the heat source side, causing the temperature of the heat exchanger on the user side to decrease. Ideally, an air conditioning unit functions as a heat pump, using the heat exchanger on the heat source side as an evaporator to lower its temperature during heating operation and the heat exchanger on the user side as a condenser to raise its temperature. Therefore, defrost operation, which lowers the temperature of the heat exchanger on the user side, temporarily degrades the heat pump's function, a situation undesirable to the user. Thus, it is desirable for defrost operation to be as short as possible with minimal temperature fluctuations.

[0006] To date, while numerous studies have been conducted on defrosting technologies, few have focused on increasing the amount of heat required. For example, the method in Patent Document 1 heats the inverter to prevent liquid return during defrosting operation, a specific environmental condition, rather than aiming to improve the performance of the refrigeration and air conditioning unit under normal defrosting conditions. Furthermore, the method of heating the intelligent power module is only effective when a refrigerant-based method is used to cool the inverter, and because it controls the inverter's heat output, it does not necessarily improve the defrosting operation itself. Summary of the Invention

[0007] This disclosure was made to solve the above-mentioned problems, and its purpose is to provide a refrigeration and air conditioning device that can shorten the time when the heating capacity is reduced due to defrosting.

[0008] The refrigeration and air conditioning apparatus disclosed herein includes: a refrigerant circuit, which is formed by connecting a compressor, a first heat exchanger, a throttling device, a second heat exchanger and a four-way valve via piping, and supplies refrigerant circulation; a temperature sensor for measuring the temperature of the compressor; and a heating control unit that, during defrosting operation of the first heat exchanger, raises the temperature of the compressor if a decrease in the measured value of the temperature sensor is detected.

[0009] According to the refrigeration and air conditioning apparatus disclosed herein, by controlling the compressor temperature to rise if the compressor temperature falls below a predetermined value, the decrease in the temperature of the refrigerant discharged from the compressor is mitigated. Therefore, defrosting operation in the first heat exchanger can be completed earlier, and the time during which the heating capacity of the second heat exchanger decreases after defrosting operation is shortened. Attached Figure Description

[0010] Figure 1 This is a circuit diagram of the refrigeration and air conditioning device involved in Implementation Method 1.

[0011] Figure 2 This is a refrigerant circuit diagram of the refrigeration and air conditioning unit involved in Embodiment 1 during heating operation.

[0012] Figure 3 This is a circuit diagram illustrating the structure of the inverter involved in Embodiment 1.

[0013] Figure 4 This is a circuit diagram showing the structure of the excitation current command creation unit involved in Embodiment 1.

[0014] Figure 5 This is a circuit diagram showing the structure of the heating control unit involved in Embodiment 1.

[0015] Figure 6 It is a graph showing the relationship between the discharge temperature of the compressor, the compressor current, and time in the refrigeration and air conditioning unit involved in the comparative example.

[0016] Figure 7 It is a graph showing the relationship between the discharge temperature of the compressor, the current of the compressor, and time in the refrigeration and air conditioning device according to Embodiment 1.

[0017] Figure 8 This is a flowchart of the defrosting operation process of the refrigeration and air conditioning unit involved in Embodiment 1.

[0018] Figure 9 This is a circuit diagram of the refrigeration and air conditioning device involved in Embodiment 2.

[0019] Figure 10It is a graph showing the relationship between the discharge temperature of the compressor, the current of the compressor, and time in the refrigeration and air conditioning device according to Embodiment 2. Detailed Implementation

[0020] Implementation method 1.

[0021] The refrigeration and air conditioning apparatus 100 according to Embodiment 1 will now be described. Note that the sizes of the constituent components shown in the following drawings may differ from the actual dimensions. Furthermore, structures marked with the same reference numerals in the following drawings are identical or equivalent structures, as is common throughout the specification. Also, the way the constituent elements appear throughout the specification is merely illustrative and not limited to these descriptions.

[0022] <Structure of Refrigeration and Air Conditioning Units>

[0023] Figure 1 This is a circuit diagram of the refrigeration and air conditioning unit 100 according to Embodiment 1. (As shown...) Figure 1 As shown, the refrigeration and air conditioning unit 100 has a refrigerant circuit, which is formed by connecting the compressor 1, the first heat exchanger 2, the throttling device 3, the second heat exchanger 4, the four-way valve 5, and the energy storage unit 6 via piping 101, and supplies refrigerant for circulation. The refrigeration and air conditioning unit 100 has a temperature sensor 30 and a control device 15.

[0024] Compressor 1 draws in refrigerant, compresses it to a high temperature and high pressure state, and then discharges it. Compressor 1 consists of an inverter compressor with controllable capacity. A motor 11 is built into compressor 1. Motor 11 drives the compression mechanism (not shown) of compressor 1 to generate power for compressor 1. Motor 11 is electrically connected to inverter 20. The drive of motor 11 is controlled by inverter 20. Motor 11 has a winding (not shown) that forms a contact surface 11a in contact with the refrigerant, and an iron core, which serves as a mechanism for receiving heat energy from the refrigerant. A heat control unit 21 is provided in inverter 20.

[0025] The first heat exchanger 2 and the second heat exchanger 4 are used to exchange heat between the refrigerant and a heat medium such as air. The first heat exchanger 2 and the second heat exchanger 4 are, for example, finned tube type heat exchangers. The first heat exchanger 2 is, for example, located outdoors. The second heat exchanger 4 is, for example, located indoors. When the refrigeration and air conditioning unit 100 is in cooling operation, the first heat exchanger 2 functions as a condenser. When the refrigeration and air conditioning unit 100 is in heating operation, the first heat exchanger 2 functions as an evaporator. The following description uses an example where the first heat exchanger 2 is located outdoors and the second heat exchanger 4 is located indoors.

[0026] The throttling device 3 is used to expand and depressurize the refrigerant. The throttling device 3 is, for example, an electronic expansion valve or other device whose opening degree can be arbitrarily controlled. The opening degree of the throttling device 3 is controlled, for example, by the control device 15. The throttling device 3 is connected between the first heat exchanger 2 and the second heat exchanger 4. The throttling device 3 causes the refrigerant flowing out of the heat exchanger that functions as a condenser in either the first heat exchanger 2 or the second heat exchanger 4 to flow into the other heat exchanger that functions as an evaporator at a low temperature and low pressure. When the refrigeration and air conditioning unit 100 is in cooling operation, the refrigerant flowing out of the first heat exchanger 2 flows into the throttling device 3, becomes low in temperature and low in pressure, and then flows into the second heat exchanger 4.

[0027] The four-way valve 5 has the function of switching the flow direction of the refrigerant during heating and the flow direction of the refrigerant during cooling. The operation of the four-way valve 5 is controlled, for example, by the control device 15. The four-way valve 5 switches the refrigerant flow path so that the discharge side of the compressor 1 is connected to the heat exchangers that function as condensers in the first heat exchanger 2 and the second heat exchanger 4. The energy storage tank 6 is used to store the remaining refrigerant.

[0028] Temperature sensor 30 detects the temperature of the refrigerant discharged from compressor 1. Temperature sensor 30 is installed at the discharge port 1a of compressor 1. Temperature sensor 30 is, for example, disposed on the piping 101 connecting compressor 1 to four-way valve 5. The temperature information measured by temperature sensor 30 is input to mode determination unit 22 of control device 15.

[0029] The control device 15 includes a mode determination unit 22 that determines the operating mode of the inverter 20 based on temperature information measured by the temperature sensor 30. The operating modes include a high-efficiency operation mode as a normal mode and a heating-priority operation mode executed during defrosting operation.

[0030] The high-efficiency operation mode is the normal operation mode, which optimizes the energy efficiency of the refrigeration and air conditioning unit 100. The high-efficiency operation mode can be achieved using known methods. The heating-priority operation mode is an operation that increases the heat output of the motor 11 by intentionally lowering the power factor of the motor 11 and increasing the current of the compressor 1. During defrosting operation based on the high-efficiency operation mode, if the measured value of the temperature sensor 30 decreases, the operation mode changes to the heating-priority operation mode, and the temperature of the compressor 1 is controlled to rise. In the heating-priority operation mode, the desired heating amount is obtained with a current that does not exceed the rated current I[A]. Preferably, the motor 11 used has a winding resistance R[Ω], rated input P[W], and rated current I[A] such that the relationship is 0.001 < (3*I*I*R) / P. The reason is that (3*I*I*R) in the parentheses above represents the rated heat generation [W] of the winding of motor 11. In a high-efficiency motor where the heat generation ratio relative to the output of motor 11 is less than 0.001, the heating effect of the winding on the liquid refrigerant is almost negligible.

[0031] The mode determination unit 22 generates a mode signal corresponding to the operating mode. The mode signal generated by the mode determination unit 22 is input to the inverter 20 and used in the processing of the heat control unit 21. The heat control unit 21 starts and stops according to the mode signal input from the mode determination unit 22. Details regarding the heat control unit 21 will be described later.

[0032] The control device 15 includes a microcomputer. The microcomputer may include, for example, a control and processing unit such as a CPU (Central Processing Unit). The microcomputer has I / O ports for managing input / output. The microcomputer also has a storage unit (not shown). This storage unit may be a volatile storage device such as random access memory (RAM) capable of temporarily storing data, or a non-volatile auxiliary storage device such as a hard disk or flash memory capable of long-term data storage. The storage unit holds data representing the processing steps performed by the control and processing unit as a program. The control and processing unit executes processing based on this program data, thus implementing the processing of each part.

[0033] The refrigeration and air conditioning unit 100 operates in cooling, heating, and defrosting modes under the control of the control device 15. The control device 15 switches the refrigerant flow direction by controlling the operation of the four-way valve 5 to perform any one of the following operations: cooling, heating, or defrosting.

[0034] <Refrigeration Operation>

[0035] In the refrigeration operation of the air conditioning unit 100, the first heat exchanger 2 functions as a condenser, and the second heat exchanger 4 functions as an evaporator. For example... Figure 1 As shown, during refrigeration operation, the refrigerant, compressed into a high-temperature and high-pressure gaseous state by the compressor 1, is discharged from the compressor 1 and flows through the four-way valve 5 into the first heat exchanger 2, which functions as a condenser. In the first heat exchanger 2, the gaseous refrigerant exchanges heat with the outdoor air, condensing and liquefying. The liquid refrigerant flows into the throttling device 3, where it expands and depressurizes, becoming a low-temperature and low-pressure gas-liquid two-phase refrigerant. The gas-liquid two-phase refrigerant flows into the second heat exchanger 4, which functions as an evaporator, where it exchanges heat with the indoor air, evaporating and vaporizing. At this time, the indoor air is cooled, implementing refrigeration indoors. The evaporated, low-temperature and low-pressure gaseous refrigerant is drawn into the compressor 1 through the four-way valve 5.

[0036] <Heating Operation>

[0037] Figure 2 This is a refrigerant circuit diagram of the refrigeration and air conditioning unit 100 according to Embodiment 1 during heating operation. During heating operation, the first heat exchanger 2 functions as an evaporator, and the second heat exchanger 4 functions as a condenser. Figure 2 As shown, during heating operation, the refrigerant, compressed into a high-temperature and high-pressure gaseous state by the compressor 1, is discharged from the compressor 1 and flows through the four-way valve 5 into the second heat exchanger 4, which functions as a condenser. In the second heat exchanger 4, the gaseous refrigerant exchanges heat with the indoor air and condenses and liquefies. At this time, the indoor air is heated, and heating is implemented indoors. The liquid refrigerant flows into the throttling device 3, where it is expanded and depressurized to become a low-temperature and low-pressure gas-liquid two-phase refrigerant. Then, the gas-liquid two-phase refrigerant flows into the first heat exchanger 2, which functions as an evaporator, where it exchanges heat with the outdoor air and evaporates and vaporizes. The evaporated low-temperature and low-pressure gaseous refrigerant is drawn into the compressor 1 through the four-way valve 5.

[0038] During heating operation, the first heat exchanger 2 releases heat to the cold outside air, thereby maintaining a temperature lower than the outside air temperature. If heating continues, moisture from the outside air may adhere to the first heat exchanger 2, causing frost to form. To prevent frost growth on the first heat exchanger 2 and an increase in its ventilation resistance, which could reduce heat exchange efficiency, the refrigeration and air conditioning unit 100 performs a defrost operation. For example, defrost operation is performed periodically. Defrost operation can be initiated only if certain conditions are met. These conditions could be, for example, that the outside air temperature reaches a predetermined temperature. The timing of the defrost operation is not particularly limited.

[0039] <Defrosting Operation>

[0040] During defrosting operation, the four-way valve 5 is switched to allow refrigerant to flow in the same direction as during refrigeration operation. Figure 1 The structure of the refrigerant circuit is shown. During defrosting operation, the high-temperature and high-pressure gaseous refrigerant discharged from the compressor 1 flows into the first heat exchanger 2 through the four-way valve 5. At this time, the frost adhering to the first heat exchanger 2 is melted by the heat from the high-temperature and high-pressure gaseous refrigerant. The liquid refrigerant flows out from the first heat exchanger 2 and is drawn into the compressor 1 through the throttling device 3, the second heat exchanger 4, and the four-way valve 5. Defrosting operation, for example, continues for a certain period of time. If the conditions for ending defrosting operation are met, defrosting operation ends, and heating operation restarts. The conditions for ending defrosting operation can be, for example, a certain period of time, and the conditions for ending defrosting operation are not particularly limited.

[0041] <Inverter Structure>

[0042] Figure 3 This is a circuit diagram illustrating the structure of the inverter 20 according to Embodiment 1. In the inverter 20, the response in current control is improved based on the measurement value of the temperature sensor 30 input to the control circuit 41. Figure 3 As shown, the inverter 20 is electrically connected to the control device 15 and the compressor 1, and has a power conversion unit 40 and a control circuit 41. The heat control unit 21 is provided in the control circuit 41 of the inverter 20.

[0043] The power conversion unit 40 supplies power to the motor 11 based on voltage commands generated by the control circuit 41. The power conversion unit 40 is a circuit equipped with semiconductor elements, such as IGBTs (Insulated Gate Bipolar Transformers), which perform power conversion. The switching elements of the power conversion unit 40 perform switching operations based on voltage commands.

[0044] Current sensors 42a and 42b are provided to detect the U-phase current Iu and V-phase current Iv supplied from the power conversion unit 40 to the motor 11. The values ​​of the U-phase current Iu and V-phase current Iv detected by the current sensors 42a and 42b are input to the control circuit 41.

[0045] The control circuit 41 is a circuit that generates voltage commands input to the power conversion unit 40. The control circuit 41 includes a dq conversion unit 50, a dq inverse conversion unit 55, a position and speed estimation unit 51, a speed control unit 52, an excitation current command creation unit 53, and a current control unit 54. A heat control unit 21 is provided in the excitation current command creation unit 53.

[0046] The control circuit 41 is a microcomputer equipped with a control and processing unit such as a CPU (Central Processing Unit). The control circuit 41 has I / O ports for managing input and output. The microcomputer has a storage unit (not shown). The storage unit can be a volatile storage device such as random access memory (RAM) capable of temporarily storing data, or a non-volatile auxiliary storage device such as a hard disk or flash memory capable of long-term data storage. The storage unit holds data as a program for the processing steps performed by the control and processing unit. The control and processing unit executes processing based on the program data, realizing the processing of each part.

[0047] The dq conversion unit 50 converts the information of the U-phase current Iu and V-phase current Iv input from the current sensors 42a and 42b into the excitation current Id and torque current Iq, which are the current information of the dq axis. The dq inverse conversion unit 55 converts the d-axis voltage command Vd* and q-axis voltage command Vq*, which are voltage commands on the dq axis, into AC voltage commands. The position and speed estimation unit 51 estimates the rotational position θ and rotational speed ω of the motor 11 based on the d-axis voltage command Vd*, the q-axis voltage command Vq*, the excitation current Id, and the torque current Iq. The speed control unit 52, the excitation current command creation unit 53, and the current control unit 54 control the rotational speed ω of the motor 11, respectively.

[0048] Inverter 20 controls the drive of motor 11 in a manner that the rotational speed ω of motor 11 of compressor 1 matches the speed command ω* input from control device 15. For a conventional hermetic compressor 1, since motor 11 is exposed to high-temperature and high-pressure refrigerant, no rotation sensor is built-in; therefore, the rotational position and speed of motor 11 are inferred from the current flowing to compressor 1 to operate motor 11. Inverter 20 controls the drive of motor 11 through sensorless vector control, which uses the current flowing to motor 11 to infer the rotational position θ and rotational speed ω of motor 11.

[0049] In sensorless vector control, the θ output by the position-velocity inference unit 51 is used for dq transformation and inverse dq transformation. Furthermore, in sensorless vector control, the rotational speed ω output by the position-velocity inference unit 51 is used for speed control. In the speed control unit 52, the rotational speed ω is compared with the speed command ω*, and a torque current command Iq* is generated based on the result.

[0050] The torque current command Iq* is maintained by the speed control unit 52, which includes an integrator, so that the rotational speed ω always matches the speed command ω*. The torque current command Iq*, together with the excitation current command Id* created by the excitation current command creation unit 53, is input to the current control unit 54. Details of the excitation current command creation unit 53 will be described later.

[0051] In the current control unit 54, a d-axis voltage command Vd* is generated such that the excitation current Id is consistent with the excitation current command Id*, and a q-axis voltage command Vq* is generated such that the torque current Iq is consistent with the torque current command Iq*.

[0052] The d-axis voltage command Vd* and q-axis voltage command Vq generated by the current control unit 54 are converted into AC voltage commands by the dq inverse conversion unit 55. Based on the AC voltage commands converted by the dq inverse conversion unit 55, voltage is generated from the power conversion unit 40, and the motor 11 is operated at a predetermined speed.

[0053] <Structure of Excitation Current Command Generation Unit 53>

[0054] Figure 4 This is a circuit diagram showing the structure of the excitation current command creation unit 53 according to Embodiment 1. For example... Figure 4 As shown, the excitation current command creation unit 53 includes: a high-efficiency control unit 60, which calculates the high-efficiency excitation current command Idh*; a heating control unit 21, which calculates the excitation current command Idm* for heating; and a selector 61.

[0055] Selector 61 selects between the high-efficiency excitation current command Idh* and the heating excitation current command Idm* based on the mode signal MODE generated by the mode determination unit 22 of control device 15. Then, it outputs the excitation current command Id*.

[0056] Here, the excitation current command Id* is an operational quantity for controlling the power factor of the motor 11. Generally, the power factor is set to the maximum or minimum current. In Embodiment 1, the excitation current command creation unit 53 controls the power factor by varying according to the mode signal MODE, the torque current command Iq*, and the discharge temperature Td of the compressor 1. For the excitation current command Id*, if the mode signal MODE is a mode signal MODE that defines a high-efficiency operation mode, then the excitation current command Id* is output with the U-phase current Iu and the V-phase current Iv at their minimum. For the excitation current command Id*, if the mode signal MODE is a mode signal MODE that defines a heating priority operation mode, then the excitation current command Id* is output with the U-phase current Iu and the V-phase current Iv at a predetermined maximum current value Imax.

[0057] The high-efficiency control unit 60 outputs a high-efficiency excitation current command Idh* based on the torque current command Iq*, which minimizes the U-phase current Iu and the V-phase current Iv.

[0058] The heating control unit 21 calculates the excitation current command Idm* for heating based on the torque current command Iq* and the discharge temperature Td of the compressor 1, so that the U-phase current Iu and the V-phase current Iv are the determined maximum current values ​​Imax.

[0059] If a mode signal MODE that defines a high-efficiency operation mode is input, selector 61 will output the high-efficiency excitation current command Idh* output from the high-efficiency control unit 60 as the excitation current command Id*.

[0060] If the input signal MODE defines a heating-priority operation mode, selector 61 will output the excitation current command Idm* for heating from the heating control unit 21 as the excitation current command Id*. That is, the heating control unit 21 of inverter 20 uses the excitation current command Idm* from motor 11 as the control quantity for heating control.

[0061] <Structure of the heating control unit>

[0062] Figure 5 This is a circuit diagram illustrating the structure of the heat dissipation control unit 21 according to Embodiment 1. (As shown...) Figure 5 As shown, the heating control unit 21 has a current upper limit calculation unit 70 and a limiter 71.

[0063] The current limit calculation unit 70 calculates the current limit value I_lim based on the discharge temperature Td of compressor 1 and the upper limit value Tdmax of the discharge temperature of compressor 1. The limiter 71 limits the excitation current command Idm* for heating based on the current limit value Ilim.

[0064] Next, refer to Figure 4 as well as Figure 5 The processing in the excitation current command creation unit 53 will be explained. The excitation current command creation unit 53 creates the excitation current command Id* based on the MODE signal, which defines a high-efficiency operation mode and a heating priority operation mode, the torque current command Iq*, and the discharge temperature Td of the compressor 1.

[0065] In the excitation current command creation unit 53, the torque current command Iq* is input to the high-efficiency control unit 60, which calculates the high-efficiency excitation current command Idh*, and the heating control unit 21, which calculates the excitation current command Idm* for heating. Then, the selector 61 selects, based on the mode signal MODE, whether to use the high-efficiency excitation current command Idh* or the heating excitation current command Idm* as the excitation current command Id*.

[0066] In the high-efficiency control unit 60, for example, an excitation current command Id* is generated such that the U-phase current Iu and the V-phase current Iv are minimized. The high-efficiency control unit 60 can adopt a known structure.

[0067] In the heating control unit 21, the temporary heating excitation current command Idm0* is calculated based on the torque current command Iq* and the predetermined maximum current value Imax using the following formula 1. As described above, in the current upper limit calculation unit 70, the maximum current value Imax is calculated based on the discharge temperature Td of the compressor 1 and the upper limit value Tdmax of the discharge temperature of the compressor 1.

[0068] [Formula 1]

[0069]

[0070] Furthermore, in limiter 71, the absolute value of the temporary heating excitation current command Idm0* is limited by the current upper limit value Ilim, and the heating excitation current command Idm* is calculated. The calculated heating excitation current command Idm* is output from excitation current command creation unit 53 as an excitation current command Id* whose upper limit is managed by the discharge temperature upper limit value Tdmax and the maximum current value Imax. The output excitation current command Id* is input to dq inverse converter 55 via current control unit 54, and voltage is generated from power conversion unit 40 according to the voltage command converted by dq inverse converter 55, so that motor 11 runs at a predetermined speed.

[0071] <Control during defrosting operation (comparative example)>

[0072] Figure 6 It is a graph showing the relationship between the discharge temperature of compressor 1, the current of compressor 1, and time in the refrigeration and air conditioning unit involved in the comparative example. Figure 6 This illustrates the heating-defrosting-heating operation of the refrigeration and air conditioning unit involved in the comparative example. Figure 6 In the diagram, the vertical axis represents the discharge temperature and the current of compressor 1, while the horizontal axis represents time. Additionally, in... Figure 6 In the diagram, the solid line represents the discharge temperature of compressor 1, and the dashed line represents the compressor current. For example... Figure 6As shown, in the comparative example, the heating and dehumidification operations are performed using a high-efficiency operation mode, which is the normal mode.

[0073] Figure 6 The interval of (1) is from the moment the heating operation is switched to the defrost operation. In this interval, the discharge temperature of the compressor 1 rises slightly because the refrigerant of the second heat exchanger 4, which was heated during the heating operation, flows back to the compressor 1.

[0074] Then, in more than Figure 6 In the interval (2) of point A, because the heat of compressor 1 itself is consumed for defrosting of the first heat exchanger 2, low-temperature refrigerant is drawn into compressor 1. Thus, the heat of compressor 1 itself is taken away by the refrigerant, and the discharge temperature decreases. During dehumidification operation, because the pressure of the refrigerant also decreases due to the decrease in refrigerant temperature, the current of compressor 1 is also lower than during heating. Defrosting operation continues until the frost melts, or until a certain period of time has elapsed.

[0075] exist Figure 6 At point B, the defrosting operation ends, and the four-way valve 5 is switched back to... Figure 2 The status displayed indicates the heating operation status; restart heating operation. This occurs immediately after switching from defrost operation to heating operation. Figure 6 In the interval of (3), since the heat energy of compressor 1 is used in defrosting, the discharge temperature of compressor 1 is lower than the discharge temperature of compressor 1 before defrosting operation.

[0076] Then, the discharge temperature of compressor 1 gradually rises, Figure 6 Point C returns to the temperature before defrosting operation. Figure 6 The (4) interval finally came into play as a heating operation.

[0077] Thus, in order for the refrigeration and air conditioning unit involved in the comparative example to reach a state capable of operating as a heating unit after defrosting, it needs to... Figure 6 The specified preheating time is shown in interval (3). During defrosting operation and as a preheating operation... Figure 7 In the intervals of (2) and (3), heating is not performed or the heating is insufficient, and the heating performance sought by the user cannot be achieved.

[0078] <Control during defrosting operation (example)>

[0079] Next, the control of defrosting operation in the refrigeration and air conditioning unit 100 according to Embodiment 1 will be described. Figure 7 It is a graph showing the relationship between the discharge temperature of the compressor 1, the current of the compressor 1, and time in the refrigeration and air conditioning device 100 according to Embodiment 1. Figure 7 and Figure 6 Similarly, it shows the operating states of the refrigeration and air conditioning unit according to Embodiment 1, from heating to defrosting to heating. Figure 7 In the diagram, the vertical axis represents the discharge temperature and the current of compressor 1, while the horizontal axis represents time. Additionally, in... Figure 7 In the diagram, the solid line represents the discharge temperature of compressor 1, and the dashed line represents the compressor current.

[0080] like Figure 7 As shown, the refrigeration and air conditioning unit 100 operates in a high-efficiency operating mode, which is the normal mode, during heating operation. After defrosting operation begins, if a decrease in the measured value in the temperature sensor 30 is detected during defrosting operation of the first heat exchanger 2, the refrigeration and air conditioning unit 100 switches to a heating-priority operating mode, and the temperature of the compressor 1 is increased by the heating control unit 21. The heating control unit 21 increases the temperature of the compressor 1 by increasing the losses in the motor 11. Through the processing of the heating control unit 21, the power factor of the motor 11 is intentionally reduced, thereby increasing the current of the compressor 1, which in turn increases the heat generated by the motor 11, and the temperature of the compressor 1 rises.

[0081] As mentioned above, Figure 7 The interval (1) is from the moment the heating operation is switched to the defrost operation. Because the refrigerant of the second heat exchanger 4, which was heated during the heating operation, flows back to the compressor 1, the discharge temperature of the compressor 1 rises slightly. In this interval, since the measured value of the temperature sensor 30 does not decrease, the compressor continues to operate in the normal high-efficiency operation mode.

[0082] During defrosting operation Figure 7 If the discharge temperature of compressor 1 detected by temperature sensor 30 decreases at point A, the mode determination unit 22 of control device 15 issues a command to inverter 20 to switch from normal high-efficiency operation mode to heating priority operation mode.

[0083] exist Figure 7 In the interval (2) after point A, in the heating priority operation mode, the heat control unit 21 of the inverter 20 receives an instruction from the mode determination unit 22 and controls the increase of motor 11 losses by increasing the current supplied to the motor 11 of the compressor 1. That is, the heat control unit 21 uses the value of the current supplied to the motor 11 as the control quantity. If the current of the motor 11 increases, copper losses proportional to the square of the current are generated as heat in the winding of the motor 11. The heat generated by the motor 11 is released to the refrigerant at the contact surface 11a where the motor 11 contacts the refrigerant, and the temperature of the refrigerant rises. As the heat generated by the motor 11 increases, the temperature drop of the refrigerant drawn into the compressor 1 is mitigated, and defrosting operation is performed while suppressing the drop in discharge temperature. Figure 7 The process ends at point B2. Thus, the defrosting operation... Figure 7 The time for (1) and (2) is shorter than that for the comparative example.

[0084] exist Figure 7 In the interval (3) after point B2, the defrosting operation is switched to the heating operation, and the heating operation is restarted. At this time, the operating mode issued by the mode determination unit 22 of the control device 15 to the inverter 20 causes the heating priority operation mode to continue. That is, when the heating operation starts, the process of raising the temperature of the compressor 1 by the heating control unit 21 continues.

[0085] exist Figure 7 If, at point C2 after interval (3), it is confirmed that the discharge temperature of compressor 1 has returned to the temperature before defrosting operation, then control device 15 issues a mode switching instruction from heating priority operation mode to high efficiency operation mode. As a result, the preheating time after defrosting operation... Figure 7 The time for (3) is shorter than that for the comparative example. Then, the operation of the inverter 20 is switched to a high-efficiency operation mode.

[0086] Figure 8 This is a flowchart illustrating the defrosting operation process of the refrigeration and air conditioning unit 100 according to Embodiment 1. The defrosting operation is performed through the control device 15. Figure 8 As shown, if the conditions for starting defrosting operation are met, the control device 15 starts defrosting operation. In step S01, the mode determination unit 22 of the control device 15 determines whether the measured value of the temperature sensor 30 has decreased in step S01.

[0087] If the mode determination unit 22 of the control device 15 determines in step S01 that the measured value of the temperature sensor 30 has not decreased, it moves to step S02, maintains the operating mode in high-efficiency operating mode, and repeats the process until it determines that the measured value has decreased. This range is related to... Figure 7 The interval corresponding to (1) in the middle.

[0088] If the mode determination unit 22 of the control device 15 determines in step S01 that the measured value of the temperature sensor 30 has decreased, it proceeds to step S03, changes the operating mode from high-efficiency operating mode to heating-priority operating mode, and then proceeds to step S04. In step S04, the mode determination unit 22 of the control device 15 generates a mode signal defining the heating-priority operating mode and inputs it to the heating control unit 21. This causes control to raise the temperature of the compressor 1. This time is related to... Figure 7 The A in the text corresponds to this.

[0089] In step S05, the mode determination unit 22 of the control device 15 determines whether the measured value of the temperature sensor 30 has recovered to the same level as the measured value detected by the temperature sensor 30 before defrosting operation. If the mode determination unit 22 of the control device 15 determines in step S05 that the measured value of the temperature sensor 30 has not recovered, it repeats the process until it determines that the measured value has recovered. This interval is related to... Figure 7 The intervals corresponding to (2) and (3) in the table.

[0090] If the mode determination unit 22 of the control device 15 determines in step S05 that the measured value of the temperature sensor 30 has recovered, it proceeds to step S06, changes the operating mode from the heating priority mode to the high-efficiency operating mode, generates a mode signal defined for the high-efficiency operating mode, and inputs it to the heating control unit 21. Thus, the control that caused the temperature rise of the compressor 1 to be controlled by the heating priority mode is stopped, and the high-efficiency operating mode continues. This moment corresponds to... Figure 7 The interval (4) starting from time C2.

[0091] Thus, in the refrigeration and air conditioning unit 100, since the decrease in the discharge temperature of the compressor 1 during defrosting operation and the start of heating operation can be suppressed, and the time from the start of defrosting operation and heating operation to the start of normal operation can be shortened, operation that does not cause discomfort to the user can be achieved.

[0092] In addition, since the temperature of compressor 1 is maintained by evaporating the undesirable liquid refrigerant even if it is drawn in, it also has the effect of obtaining a high-quality system where adverse conditions such as poor lubrication are unlikely to occur.

[0093] <Variation Example>

[0094] The maximum current condition exists under two conditions: a power factor lagging state and a power factor leading state. Formula 1 described above is the condition used when operating under the power factor lagging state. In the modified example of the refrigeration and air conditioning unit 100, the calculation of the temporary heating excitation current command Idm0* based on Formula 2 differs. Formula 2 is the condition used when operating under the power factor leading state.

[0095] [Equation 2]

[0096]

[0097] According to Formula 1, by increasing the magnetic flux generated in motor 11, the iron loss of motor 11 can be increased, thus enabling more efficient heating. Furthermore, according to Formula 2, since the output voltage of inverter 20 is reduced, it is effective in situations where increasing the output voltage is difficult, such as when the compressor 1's rotational speed is increased to operate.

[0098] Furthermore, it is possible to switch between the method of formula 1 in embodiment 1 and the method of formula 2 in the modified example, depending on the speed and output voltage of compressor 1.

[0099] According to the refrigeration and air conditioning unit 100 described in Embodiment 1 above, during defrost operation, if the temperature of the compressor 1 falls below a predetermined value, the heating control unit 21 controls the temperature of the compressor 1 to rise, thereby mitigating the decrease in the temperature of the refrigerant discharged from the compressor 1. Therefore, defrost operation in the first heat exchanger 2 can be completed earlier, and the time during which the heating capacity decreases in the second heat exchanger 4 after defrost operation is shortened, achieving operation that does not cause discomfort to the user. Furthermore, since the temperature of the compressor 1 can be achieved using a standard temperature sensor 30 mounted on the compressor 1, no additional components are required, thus achieving the effect of shortening the time during which the heating capacity decreases due to defrost operation at low cost. Additionally, since the temperature of the compressor 1 can be maintained at a constant level, if unwanted liquid refrigerant is drawn in, it will evaporate, resulting in a high-quality system where conditions such as poor lubrication are less likely to occur. Furthermore, since the overall heating capacity is evaluated by the average cumulative capacity of the refrigeration and air conditioning unit 100, including defrost time, the effect of shortening the defrost time leads to an increase in heating capacity. In addition, since the temperature change range of compressor 1 is reduced during the heating / defrosting operation cycle, the thermal stress of the compression mechanism is mitigated, and the reliability is improved relative to metal fatigue.

[0100] Furthermore, since the inverter 20, which is equipped with the heating control unit 21, is standardly installed on the compressor 1, no additional components are required, making it possible to obtain a refrigeration and air conditioning unit 100 that reduces the time when heating capacity is reduced due to defrosting operation at a low cost. By raising the temperature of the compressor 1 through the heating control unit 21 installed on the inverter 20, the time of insufficient capacity during defrosting operation and at the start of heating is shortened, thereby improving user comfort.

[0101] Furthermore, by controlling the increase in losses of the motor 11 through the heat control unit 21, the motor 11 heats up, which can mitigate the decrease in refrigerant discharged from the compressor 1. In addition, since the inverter 20 is standardly equipped with the compressor 1, no additional components are required, so a refrigeration and air conditioning unit 100 that can reduce the time when the heating capacity is reduced due to defrosting operation can be obtained at a low cost.

[0102] In addition, the heating control unit 21 uses the current value of the motor 11 as a control quantity and uses the inverter 20 to implement normal control to raise the temperature of the compressor 1, thereby shortening the time when the heating capacity is reduced.

[0103] In addition, since the heating control unit 21 uses the excitation current command Id* of the motor 11 as the control quantity, the temperature of the compressor 1 can be increased by applying the normal control implemented by the inverter 20, which can shorten the time when the heating capacity is reduced.

[0104] In addition, since the heating control unit 21 is also activated when the defrosting operation ends and the heating operation begins, the preheating time after the defrosting operation can be shortened, thus enabling operation that does not cause discomfort to the user.

[0105] In addition, a temperature sensor 30 for measuring the temperature of the compressor 1 is disposed at the discharge port 1a of the compressor 1. Therefore, by rapidly measuring the temperature change in the compressor 1 for heat control, the time during which the heating capacity decreases due to defrosting operation is shortened, and operation that does not cause discomfort to the user can be achieved.

[0106] Implementation method 2.

[0107] <Structure of Refrigeration and Air Conditioning Units>

[0108] Figure 9 This is a circuit diagram of the refrigeration and air conditioning unit 100 according to Embodiment 2. The structure of the heating compressor 1 in Embodiment 2 is different from that in Embodiment 1. In Embodiment 2, the same reference numerals are used for parts that are common to Embodiment 1, and the description is omitted. The description focuses on the differences from Embodiment 1. The heating control unit 21 in Embodiment 2 differs from the control motor 11 in Embodiment 1 in that it controls the heater 80 installed on the compressor 1.

[0109] like Figure 9 As shown, in the refrigeration and air conditioning device 100 according to Embodiment 2, a heater 80 is installed on the compressor 1 to prevent liquid refrigerant from remaining in the compressor 1 when operation stops. The heating amount of the heater 80 is controlled by the heating control unit 21 of the control device 15.

[0110] Figure 10It is a graph showing the relationship between the discharge temperature Td of the compressor 1, the current of the compressor 1, and time in the refrigeration and air conditioning device 100 according to Embodiment 2. Figure 10 This illustrates the heating-defrosting-heating operation of the refrigeration and air conditioning unit 100 according to Embodiment 2. Figure 10 In the diagram, the vertical axis represents the discharge temperature and the start (ON) / stop (OFF) operation of the heater, while the horizontal axis represents time. Additionally, in... Figure 10 In the diagram, the solid line represents the discharge temperature of compressor 1, and the dashed line represents the compressor current.

[0111] like Figure 10 As shown, the refrigeration and air conditioning unit 100 operates in the same high-efficiency operation mode as in Embodiment 1 during heating operation. After the start of defrosting operation, if a decrease in the measured value of the temperature sensor 30 is detected during defrosting operation of the first heat exchanger 2, the refrigeration and air conditioning unit 100 sends a MODE signal, which defines a heating priority operation mode, to the heating control unit 21 from the mode determination unit 22. The heating control unit 21 increases the heat output of the heater 80 installed on the compressor 1 to raise the temperature of the compressor 1.

[0112] like Figure 10 As shown, the refrigeration and air conditioning unit 100 operates in the same high-efficiency operating mode as in Embodiment 1 during heating operation. After the start of defrosting operation, after... Figure 10 When the discharge temperature of compressor 1 falls below point A in the range of (1), control device 15 starts heating priority operation mode.

[0113] exist Figure 10 In the interval of (2), by using heater 80 to heat compressor 1, defrosting operation is performed while suppressing the decrease in the discharge temperature of compressor 1. Figure 10 The time of (1) and (2) Figure 6 The comparison example is shorter in time.

[0114] After the defrosting process is complete, Figure 10 Point B2 is switched to heating operation. Figure 10 The heating operation of the (3) interval is restarted, but the heating priority operation mode based on heater 80 continues.

[0115] Then, if it is confirmed that the discharge temperature Td of compressor 1 has recovered, then in Figure 10 Point C2 issues a mode switching instruction from heating priority operation mode to high efficiency operation mode, and switches to high efficiency operation mode.

[0116] Therefore, the preheating time after defrosting operation is... Figure 10 (3) time and Figure 6 Compared to the comparative example, the time is shorter. Thus, in the refrigeration and air conditioning unit 100 of Embodiment 2, the decrease in the discharge temperature Td of the compressor 1 during defrost operation and at the start of heating operation can be suppressed, and the time from defrost operation to the start of normal operation after heating operation can be shortened. Therefore, operation that does not cause discomfort to the user can be achieved.

[0117] According to Embodiment 2 described above, the refrigeration and air conditioning unit 100 heats the compressor 1 by means of a heater 80 installed on the compressor 1, thus mitigating the decrease in refrigerant discharged from the compressor 1. Furthermore, since the heater 80 is standardly installed on the compressor 1, no additional components are required, making it possible to obtain a refrigeration and air conditioning unit 100 that reduces the time when heating capacity decreases due to defrosting operation at a low cost.

[0118] Explanation of reference numerals in the attached figures:

[0119] 1... Compressor; 1a... Discharge port; 2... First heat exchanger; 3... Throttling device; 4... Second heat exchanger; 5... Four-way valve; 6... Energy storage device; 11... Motor; 11a... Contact surface; 15... Control device; 20... Inverter; 21... Heating control unit; 22... Mode determination unit; 30... Temperature sensor; 40... Power conversion unit; 41... Control circuit; 42a... Current sensor; 42b... Current sensor; 50... DQ conversion unit; 51... Position and speed inference unit; 52... Speed ​​control unit; 53... Excitation current command creation unit; 54... Current control unit; 55... DQ inverse conversion unit; 60... High-efficiency control unit; 61... Selector; 70... Current upper limit calculation unit; 71... Limiter; 80... Heater; 100... Refrigeration and air conditioning unit; 101... Piping.

Claims

1. A refrigeration and air conditioning device, characterized in that, have: The refrigerant circuit is formed by connecting the compressor, the first heat exchanger, the throttling device, the second heat exchanger, and the four-way valve through piping to circulate the refrigerant. A temperature sensor measures the temperature of the compressor; The motor is built into the compressor; Inverter, controlling the motor; as well as A heating control unit, located in the inverter, raises the compressor temperature if a decrease in the measured value of the temperature sensor is detected during defrosting operation of the first heat exchanger. During the defrosting operation of the first heat exchanger, if a decrease in the measured value of the temperature sensor is detected, the heating control unit begins to control the temperature of the compressor to rise. After the defrosting operation of the first heat exchanger begins, if the measured value of the temperature sensor is the same as the measured value detected by the temperature sensor before the defrosting operation of the first heat exchanger begins, the heating control unit stops controlling the temperature rise of the compressor.

2. The refrigeration and air conditioning device according to claim 1, characterized in that, The heating control unit uses the value of the motor's excitation current command as a control quantity to generate a negative excitation current command.

3. The refrigeration and air conditioning device according to claim 1 or 2, characterized in that, After switching from heating operation to defrosting operation, the heating control unit continues to operate in the normal high-efficiency mode as long as the temperature sensor reading does not decrease.

4. The refrigeration and air conditioning device according to claim 1 or 2, characterized in that, The motor has a contact surface that contacts the piping that supplies the refrigerant.

5. The refrigeration and air conditioning device according to claim 1 or 2, characterized in that, The heating control unit increases the temperature of the compressor by increasing the wear and tear on the motor.

6. The refrigeration and air conditioning device according to claim 1 or 2, characterized in that, The relationship between the winding resistance R [Ω], rated input P [W] and rated current I [A] of the motor satisfies 0.001 < (3 * I * I * R) / P.

7. The refrigeration and air conditioning device according to claim 1 or 2, characterized in that, The heating control unit raises the temperature of the compressor at the start of heating operation.

8. The refrigeration and air conditioning device according to claim 1 or 2, characterized in that, The temperature sensor is located at the compressor's outlet.

Images