WO2013099147A1

WO2013099147A1 - Refrigeration cycle device

Info

Publication number: WO2013099147A1
Application number: PCT/JP2012/008056
Authority: WO
Inventors: 善直中本; 章博田中; 太一梅田
Original assignee: パナソニック株式会社
Priority date: 2011-12-26
Filing date: 2012-12-17
Publication date: 2013-07-04
Also published as: JP2013133966A

Abstract

A zero-cross detection means (20) detects the zero-cross point of the alternating current power supply voltage supplied to a refrigeration cycle device, and generates a zero-cross signal (S20) indicating a period of time in which the alternating current power supply voltage is less than zero volts. A power supply voltage estimation means (21) estimates the effective value (VHP) of the alternating current power supply voltage on the basis of the zero-cross signal (S20). A compressor power consumption estimation means (25) estimates the compressor power consumption (Wc) on the basis of the current value (IHP) for the power supply current supplied to the refrigeration cycle device and the effective value (VHP). A discharge pressure estimation means (11) estimates the discharge pressure (Pdc) of the refrigerant discharged from the compressor on the basis of the compressor power consumption (Wc), the evaporator temperature (Te), the outside air temperature (Tat), and the compressor rotational frequency (f).

Description

Refrigeration cycle equipment

The present invention relates to a refrigeration cycle apparatus.

FIG. 9 is a block diagram showing a configuration of a refrigeration cycle apparatus according to the first prior art mounted on a heat pump water heater. The refrigeration cycle apparatus of FIG. 9 includes a refrigerant circuit 5 that is formed by sequentially connecting a compressor 1, a radiator 2, an expansion valve 3, and an evaporator 4 in an annular manner using pipes. Here, the water inlet pipe 6 and the hot water outlet pipe 7 are connected to the radiator 2. The pressure switch 8 is connected to a branch pipe 10 branched from a pipe between the compressor 1 and the radiator 2. Furthermore, the switch means 9 is provided on an AC power supply circuit that supplies AC power to the refrigeration cycle apparatus (see, for example, Patent Document 1).

9, the high-pressure refrigerant discharged from the compressor 1 is supplied to the radiator 2, and heat is exchanged with the water in the water inlet pipe 6 in the radiator 2, and then supplied to the expansion valve 3. Further, the refrigerant is decompressed by the expansion valve 3, supplied to the evaporator 4, absorbs heat, and is sucked into the compressor 1. Here, for example, in a refrigeration cycle apparatus mounted on an air conditioner that uses R410A as a refrigerant, an abnormal increase in discharge pressure can be detected by estimating the discharge pressure from the condensation temperature of the radiator 2 (condenser). . However, for example, in a refrigeration cycle apparatus mounted on a heat pump water heater that uses carbon dioxide as a refrigerant, it is difficult to estimate the discharge pressure from the temperature of the radiator 2 because the discharge pressure exceeds the critical pressure. Therefore, the pressure switch 8 is provided so as to operate when the pressure of the refrigerant discharged from the compressor 1 exceeds a preset threshold value. Further, the switch means 9 is switched from on to off in accordance with the operation of the pressure switch 8 to cut off the AC power supply circuit. Therefore, even in a refrigeration cycle apparatus in which the refrigerant is in a supercritical state on the high pressure side, an abnormal increase in discharge pressure can be detected to stop the operation of the refrigeration cycle apparatus, and an abnormal increase in discharge pressure can be prevented.

FIG. 10 is a block diagram showing the configuration of the refrigeration cycle apparatus according to the second prior art mounted on the heat pump water heater. The refrigeration cycle apparatus of FIG. 10 includes a refrigerant circuit 5 configured in the same manner as the refrigerant circuit 5 of FIG. 9, a discharge pressure estimation means 111, a compressor current detection means 12, a compressor rotation speed detection means 13, and heat dissipation. It comprises an outlet temperature detecting means 14 and an evaporator temperature detecting means 15. Here, the compressor current detecting means 12 detects the current value of the current flowing through the electric motor of the compressor 1, and the compressor rotational speed detecting means 13 detects the rotational speed of the electric motor of the compressor 1. The radiator outlet temperature detecting means 14 detects the temperature of the refrigerant sent from the radiator 2 to the expansion valve 3, and the evaporator temperature detecting means 15 detects the refrigerant temperature in the evaporator 4. Furthermore, the discharge pressure estimation means 111 does not include pressure detection means such as a pressure switch or a pressure sensor, and estimates the discharge pressure from the operating state of the refrigeration cycle apparatus. Specifically, the discharge pressure estimation means 111 is based on at least the detection values from the compressor current detection means 12, the compressor rotation speed detection means 13, the radiator outlet temperature detection means 14, and the evaporator temperature detection means 15. The discharge pressure is estimated using the relationship between the electric power consumption of the electric motor and the discharge pressure, which are obtained in advance (see, for example, Patent Document 2). According to the refrigeration cycle apparatus of FIG. 10, since the discharge pressure estimation means 11 is provided, the discharge pressure can be detected without the pressure detection means such as a pressure switch or a pressure sensor.

JP 2005-249293 A JP 2010-2090 A

However, in the refrigeration cycle apparatus described in Patent Document 1, the pressure switch 8 and the branch pipe 10 rise to substantially the same temperature (about 90 to 120 ° C.) as the refrigerant discharged from the compressor 1. Accordingly, there is a problem that heat leakage from the pressure switch 8 and the branch pipe 10 occurs and the energy consumption efficiency of the refrigeration cycle apparatus is lowered.

In addition, the refrigeration cycle apparatus described in Patent Document 2 includes the discharge pressure estimation means 11 that estimates the discharge pressure from the operating state of the refrigeration cycle apparatus without using pressure detection means such as a pressure switch or a pressure sensor. Heat leakage does not occur. However, in order to use for calculation of compressor power, it is necessary to include compressor current detection means 12 for detecting the current value of the current flowing through the electric motor of the compressor 1, which leads to an increase in cost of the refrigeration cycle apparatus. There was a problem.

The object of the present invention is to solve the above-mentioned problems, and to reduce the discharge pressure of the compressor with a low-cost configuration as compared with the prior art without providing pressure detection means such as a pressure sensor or pressure switch and compressor current detection means. The object is to provide a refrigeration cycle apparatus that can be estimated.

A refrigeration cycle apparatus according to the present invention includes an annularly connected compressor, a radiator, an expansion valve, and an evaporator, a refrigerant circuit that circulates refrigerant, and a control unit that controls the refrigerant circuit. In the refrigeration cycle apparatus provided, the control means detects a zero cross point of the AC power supply voltage supplied to the refrigeration cycle apparatus, and generates a zero cross signal indicating a period during which the AC power supply voltage is less than zero volts. Power supply voltage estimating means for estimating an effective value of the AC power supply voltage based on the zero cross signal, a current value of a power supply current supplied to the refrigeration cycle apparatus, and an effective value of the estimated AC power supply voltage The compressor power consumption estimating means for estimating the power consumption of the refrigeration cycle device and outputting the estimated power consumption as the power consumption of the compressor, and the power consumption of the compressor. A discharge pressure for estimating the discharge pressure of the refrigerant discharged from the compressor based on the electric power, the evaporator temperature that is the temperature of the refrigerant circulating in the evaporator, the outside air temperature, and the rotation speed of the compressor Estimation means, and the control means controls the compressor or the expansion valve based on the estimated discharge pressure.

Therefore, it is possible to estimate the discharge pressure of the compressor with a low-cost configuration as compared with the prior art without providing pressure detection means such as a pressure sensor or a pressure switch and compressor current detection means. For this reason, it is possible to accurately detect the occurrence of an abnormal increase in the discharge pressure as compared with the prior art, appropriately stop the operation of the refrigeration cycle apparatus, and prevent the operation at an abnormal pressure exceeding the design pressure.

According to the refrigeration cycle apparatus according to the present invention, the compressor power consumption used for estimating the discharge pressure is estimated using the current value of the power supply current detected by the power supply current detection means and the zero volt point of the AC power supply voltage. Since the estimation is performed using the effective value of the AC power supply voltage, the discharge pressure of the compressor can be reduced with a low-cost configuration compared to the prior art without providing pressure detection means such as a pressure sensor or a pressure switch and compressor current detection means. Can be estimated.

It is a block diagram which shows the structure of the refrigerating-cycle apparatus which concerns on Embodiment 1 of this invention. (A) is a timing chart of the alternating current power supply voltage supplied to the refrigeration cycle apparatus of FIG. 1, and (b) is a timing chart of the zero cross signal S20 from the zero cross detection means 20 of FIG. 2 is a graph showing a function fvhp stored in the memory 21m of FIG. 1 and showing a relationship between the pulse width Dn of the zero cross signal S20 and the effective value VHP of the AC power supply voltage. It is a table stored in the memory 23m of FIG. 1, and is a table showing a relationship between the rotational speed FM of the blower 17 and the power consumption Wf of the blower 17. 2 is a table stored in the memory 24m of FIG. 1 and showing a relationship between the power supply current value IHP and the power consumption Wp of the control unit 18. It is a table stored in the memory 11m of FIG. 1, and is a table showing the relationship between the power consumption Wc and the evaporator temperature Te of the compressor 1 and the discharge pressure Pd. It is a block diagram which shows the structure of the refrigerating-cycle apparatus which concerns on Embodiment 2 of this invention. It is a graph which shows the correction method of the function fvhp by the power supply voltage estimation means 21A of FIG. It is a block diagram which shows the structure of the refrigerating-cycle apparatus which concerns on the 1st prior art mounted in a heat pump water heater. It is a block diagram which shows the structure of the refrigerating-cycle apparatus which concerns on the 2nd prior art mounted in a heat pump water heater.

A refrigeration cycle apparatus according to a first aspect includes an annularly connected compressor, a radiator, an expansion valve, and an evaporator, a refrigerant circuit that circulates refrigerant, and a control unit that controls the refrigerant circuit. The control means detects a zero cross point of the AC power supply voltage supplied to the refrigeration cycle apparatus and generates a zero cross signal indicating a period during which the AC power supply voltage is less than zero volts. Detecting means; power supply voltage estimating means for estimating an effective value of the AC power supply voltage based on the zero cross signal; a current value of a power supply current supplied to the refrigeration cycle apparatus; and an effective value of the estimated AC power supply voltage. A compressor power consumption estimating means for estimating the power consumption of the refrigeration cycle device based on the value and outputting as power consumption of the compressor, and the compressor A discharge that estimates the discharge pressure of the refrigerant discharged from the compressor based on the power consumption, the evaporator temperature that is the temperature of the refrigerant circulating in the evaporator, the outside air temperature, and the rotation speed of the compressor Pressure estimation means, and the control means controls the compressor or the expansion valve based on the estimated discharge pressure.

The refrigeration cycle apparatus according to a second aspect is the refrigeration cycle apparatus according to the first aspect, wherein the power supply voltage estimation means is based on the zero cross signal and the period length of the period in which the AC power supply voltage is less than zero volts. The effective value of the AC power supply voltage is estimated using the relationship between the effective value of the AC power supply voltage.

Therefore, the discharge pressure of the compressor can be estimated with an inexpensive configuration compared to the conventional technology.

The refrigeration cycle apparatus according to a third aspect is the refrigeration cycle apparatus according to the second aspect, wherein the control means detects a DC voltage after rectifying and smoothing the AC power supply voltage before the operation of the compressor. And a DC voltage detecting means for detecting an effective value of the AC power supply voltage before operation of the compressor based on the detected DC voltage, and the power supply voltage estimation means is provided before the operation of the compressor. Using the effective value of the AC power supply voltage and the period length when the DC voltage is detected, the relationship between the period length of the period in which the AC power supply voltage is less than zero volts and the effective value of the AC power supply voltage And the effective value of the AC power supply voltage is estimated using the corrected relationship.

Therefore, the effective value of the AC power supply voltage can be estimated with high accuracy compared to the refrigeration cycle apparatuses according to the first and second aspects, and as a result, the discharge pressure can be estimated with high accuracy.

The refrigeration cycle apparatus according to a fourth aspect is the refrigeration cycle apparatus according to any one of the first to third aspects, wherein the discharge pressure estimation means includes the estimated power consumption of the compressor and the evaporation. After the discharge pressure is estimated using the relationship between the compressor temperature and the discharge pressure, the estimated discharge pressure is corrected using the compressor rotation speed and the outside air temperature.

A refrigeration cycle apparatus according to a fifth aspect is the refrigeration cycle apparatus according to any one of the first to fourth aspects, wherein the refrigeration cycle apparatus promotes evaporation of the refrigerant in the evaporator. The control means further includes a blower power consumption estimation means for estimating the power consumption of the blower based on the number of rotations of the blower, and the compressor power consumption estimation means includes the refrigeration unit. The power consumption of the blower is subtracted from the power consumption of the cycle device, and the power consumption after the subtraction is output as the power consumption of the compressor.

Therefore, the compressor power consumption can be estimated with higher accuracy than the refrigeration cycle apparatuses according to the first to fourth aspects, and as a result, the discharge pressure can be estimated with high accuracy.

The refrigeration cycle apparatus according to a sixth aspect is the refrigeration cycle apparatus according to the fifth aspect, wherein the control means detects the rotational speed of the blower and outputs it to the blower power consumption estimation means. Is further provided.

A refrigeration cycle apparatus according to a seventh aspect is the refrigeration cycle apparatus according to any one of the first to sixth aspects, wherein the control means sets a current value of a power supply current supplied to the refrigeration cycle apparatus. And a controller power consumption estimating means for estimating the power consumption of the control means based on the power consumption of the control means by subtracting the power consumption of the control means from the power consumption of the refrigeration cycle apparatus. Is output as the power consumption of the compressor.

Therefore, the compressor power consumption can be estimated with higher accuracy than the refrigeration cycle apparatuses according to the first to sixth aspects, and as a result, the discharge pressure can be estimated with high accuracy.

The refrigeration cycle apparatus according to an eighth aspect is the refrigeration cycle apparatus according to any one of the first to seventh aspects, wherein the control means sets the estimated discharge pressure to a predetermined discharge pressure target value. The compressor or the expansion valve is controlled so as to substantially match.

Therefore, the refrigeration cycle apparatus can be operated with relatively high energy efficiency.

The refrigeration cycle apparatus according to a ninth aspect is the refrigeration cycle apparatus according to any one of the first to eighth aspects, wherein the control means is a discharge pressure preset for the estimated discharge pressure. When larger than the threshold value, the compressor is stopped or the rotational speed of the compressor is reduced.

Therefore, an abnormal increase in the discharge pressure of the refrigeration cycle apparatus can be prevented.

The refrigeration cycle apparatus according to a tenth aspect is the refrigeration cycle apparatus according to any one of the first to eighth aspects, wherein the control means is a discharge pressure preset for the estimated discharge pressure. When larger than the threshold value, the opening degree of the expansion valve is increased.

The refrigeration cycle apparatus according to an eleventh aspect is the refrigeration cycle apparatus according to any one of the first to tenth aspects, wherein the control means is configured such that when the compressor is driven, the pressure of the refrigerant is the refrigerant. Control is performed so that a supercritical pressure is obtained on the high pressure side of the circuit.

Therefore, the efficiency of the refrigeration cycle apparatus can be improved.

A refrigeration cycle apparatus according to a twelfth aspect is characterized in that in the refrigeration cycle apparatus according to the eleventh aspect, the refrigerant is carbon dioxide.

Therefore, even if the refrigerant leaks, there is no danger of combustion, and the refrigeration cycle apparatus can be operated safely.

A refrigeration cycle apparatus according to a thirteenth aspect is the refrigeration cycle apparatus according to any one of the first to twelfth aspects, wherein the control means determines a current value of a power supply current supplied to the refrigeration cycle apparatus. It further comprises power supply current detection means for detecting and outputting to the compressor power consumption estimation means.

The refrigeration cycle apparatus according to a fourteenth aspect is the refrigeration cycle apparatus according to any one of the first to thirteenth aspects, wherein the control means detects the rotation speed of the compressor and estimates the discharge pressure. The compressor rotation speed detection means for outputting to the means is further provided.

The refrigeration cycle apparatus according to the fifteenth aspect is the refrigeration cycle apparatus according to any one of the first to fourteenth aspects, wherein the evaporator temperature is detected and output to the discharge pressure estimating means. It further has a detecting means.

The refrigeration cycle apparatus according to a sixteenth aspect is the refrigeration cycle apparatus according to any one of the first to fifteenth aspects, wherein the outside air temperature detecting means detects the outside air temperature and outputs the detected temperature to the discharge pressure estimating means. Is further provided.

Embodiments according to the present invention will be described below with reference to the drawings. In addition, the same code | symbol is attached | subjected about the same component. Further, the present invention is not limited to the following embodiments.

(Embodiment 1)
FIG. 1 is a block diagram showing a configuration of a refrigeration cycle apparatus according to Embodiment 1 of the present invention. 1, the refrigeration cycle apparatus according to the present embodiment includes a refrigerant circuit 5, a control unit 18 (control means), a blower 17, an evaporator temperature detection means 15, an outside air temperature detection means 16, and a discharge temperature. And a detection means 29. Further, the control unit 18 includes a power supply current detection means 19, a zero cross detection means 20, a power supply voltage estimation means 21 provided with a memory 21m, a blower rotation speed detection means 22, and a blower power consumption estimation means provided with a memory 23m. 23, a control unit power consumption estimation means 24 having a memory 24m, a compressor power consumption estimation means 25, a compressor rotation speed detection means 28, an expansion valve control means 26, a compressor control means 27, a memory And a discharge pressure estimating means 11 having 11 m.

The refrigerant circuit 5 is configured by sequentially connecting the compressor 1, the radiator 2, the expansion valve 3 (decompression mechanism), and the evaporator 4 in an annular manner using pipes. Further, the water inlet pipe 6 and the hot water outlet pipe 7 are connected to the radiator 2. The high-pressure refrigerant discharged from the compressor 1 is supplied to the radiator 2, and heat is exchanged with the water in the water inlet pipe 6 in the radiator 2 to dissipate heat and then supplied to the expansion valve 3. Further, the refrigerant is decompressed by the expansion valve 3, supplied to the evaporator 4, absorbs heat, and is sucked into the compressor 1. The blower 17 is provided in the vicinity of the evaporator 4 so as to promote the evaporation of the refrigerant in the evaporator 4, and is controlled by the control unit 18. In the present embodiment, the refrigerant is carbon dioxide that becomes a supercritical state on the high-pressure side of the refrigerant circuit 5 when the compressor 1 is driven. When the compressor 1 is driven, the control unit 18 controls the carbon dioxide pressure to be a supercritical pressure on the high pressure side of the refrigerant circuit 5.

The evaporator temperature detection means 15 is provided on the pipe surface of the refrigerant inlet of the evaporator 4, detects the temperature of the pipe surface at the refrigerant side inlet of the evaporator 4 as the evaporator temperature Te, and indicates the evaporator temperature Te. Is output to the discharge pressure estimating means 11. Since the evaporator temperature detection means 15 detects the temperature of the pipe surface, the detected evaporator temperature Te circulates in the evaporator 4 when the operation state of the refrigeration cycle apparatus is substantially steady. It becomes substantially the same as the temperature of the refrigerant.

The outside air temperature detecting means 16 is provided on the windward side of the evaporator 4 so as to detect the temperature of the air introduced into the evaporator 4 (outside air temperature). The outside air temperature detection means 16 detects the temperature of the air introduced into the evaporator 4 as the outside air temperature Tat, and outputs a signal including the outside air temperature Tat to the discharge pressure estimation means 11. The discharge temperature detecting means 29 is provided on the surface of the pipe for introducing the refrigerant from the compressor 1 to the radiator 2, detects the discharge temperature Td, and outputs a signal including the discharge temperature Td to the expansion valve control means 26. .

When the refrigeration cycle apparatus is in operation, the compressor control means 27 sets the rotation speed fc of the compressor 1 in advance so that the heating capacity in the radiator 2 becomes a predetermined heating capacity target value. And the compressor 1 is rotated at the determined rotational speed. As a result, the refrigeration cycle apparatus can be operated by selecting a compressor rotational speed that satisfies the required heating capacity in accordance with the operating conditions.

The expansion valve control means 26 determines the opening degree of the expansion valve 3 so that the discharge temperature Td detected by the discharge temperature detection means 29 substantially matches a predetermined target discharge temperature target value set in advance. Control. By controlling in this way, the expansion valve 3 can be controlled and operated so that the energy consumption efficiency of the refrigeration cycle apparatus is maximized. The expansion valve control means 26 controls the expansion valve 3 so that the degree of superheat of the refrigerant increases as the outside air temperature Tat increases. Therefore, the degree of superheat of the refrigerant sucked into the compressor 1 correlates with the outside air temperature Tat. Have.

The power supply current detection means 19 is, for example, a current probe, detects the current value IHP of all power supply currents supplied to the refrigeration cycle apparatus, and outputs a signal including the detected power supply current value IHP to the control unit power consumption estimation means. 24 and the compressor power consumption estimation means 25.

The zero cross detection means 20 detects a zero cross point where the AC power supply voltage supplied to the refrigeration cycle apparatus crosses the 0V level, and generates a zero cross signal S20 which is a pulse signal indicating a period during which the AC power supply voltage is less than 0V. To the power supply voltage estimation means 21. The power supply voltage estimation means 21 measures the period Tn (n = 1, 2,..., N−2, n−1, n) of the zero cross signal S20 from the zero cross detection means 20, and further uses the period Tn to perform zero crossing. The pulse width Dn (n = 1, 2,..., N−2, n−1, n) of the No. S20 is measured.

2A is a timing chart of the AC power supply voltage supplied to the refrigeration cycle apparatus of FIG. 1, and FIG. 2B is a timing chart of the zero cross signal S20 from the zero cross detection means 20 of FIG. . As shown in FIGS. 2A and 2B, since the AC power supply voltage generally has a sine wave shape, the pulse width Dn of the zero cross signal S20 is inversely proportional to the effective value of the AC AC power supply voltage.

1, the power supply voltage estimation means 21 stores a function fvhp indicating the relationship between the pulse width Dn of the zero cross signal S20 and the effective value VHP of the AC power supply voltage in the memory 21m in advance. FIG. 3 is a graph showing the function fvhp stored in the memory 21m of FIG. 1 and showing the relationship between the pulse width Dn of the zero cross signal S20 and the effective value VHP of the AC power supply voltage. As shown in FIG. 3, the effective value VHP of the AC power supply voltage is inversely proportional to the pulse width Dn. The power supply voltage estimation means 21 estimates the effective value VHP of the AC power supply voltage using the pulse width Dn of the input zero-cross signal S20 and the function fvhp, and compresses the signal indicating the estimated effective value VHP of the AC power supply voltage. It outputs to the machine power consumption estimation means 25.

1, the blower rotation speed detection means 22 detects the rotation speed FM (rpm) of the blower 17 and outputs a signal indicating the detected rotation speed FM to the blower power consumption estimation means 23. The blower power consumption estimation means 23 stores in advance a table indicating the relationship between the rotational speed FM of the blower 17 and the power consumption Wf of the blower 17 in the memory 23m. FIG. 4 is a table stored in the memory 23m of FIG. 1 and showing a relationship between the rotational speed FM of the blower 17 and the power consumption Wf of the blower 17. As shown in FIG. 4, the power consumption Wf of the blower 17 increases as the rotational speed FM of the blower 17 increases. The blower power consumption estimation unit 23 estimates the power consumption Wf of the blower 17 based on the input rotation speed FM and estimates a signal indicating the estimated power consumption Wf as compressor power consumption estimation. Output to means 25.

Also, the control unit power consumption estimation means 24 stores a table indicating the relationship between the power supply current value IHP and the power consumption Wp of the control unit 18 in the memory 24m in advance. FIG. 5 is a table stored in the memory 24m of FIG. 1 and showing a relationship between the power supply current value IHP and the power consumption Wp of the control unit 18. As shown in FIG. 5, the power consumption Wp of the control unit 18 increases as the power supply current value IHP increases. The control unit power consumption estimation means 24 estimates the power consumption Wp of the control unit 18 with reference to the table of FIG. 5 based on the input power supply current value IHP, and outputs a signal indicating the estimated power consumption Wp to the compressor. Output to the power consumption estimation means 25.

The compressor power consumption estimation means 25 calculates the refrigeration cycle power consumption WHP (= IHP × VHP) based on the input power supply current value IHP and the effective value VHP of the AC power supply voltage, and the fan consumption from the refrigeration cycle power consumption WHP. The compressor power consumption Wc (= IHP × VHP−Wf−Wp) is estimated by subtracting the power value Wf and the control unit power consumption Wp. Then, a signal indicating the estimated compressor power consumption Wc is output to the discharge pressure estimating means 11.

The compressor rotation speed detection means 28 detects the rotation speed of the compressor 1 and outputs a signal indicating the compressor rotation speed f (HZ) to the discharge pressure estimation means 11.

The discharge pressure estimation means 11 stores in advance in the memory 11m a table showing the relationship between the power consumption Wc and the evaporator temperature Te of the compressor 1 and the discharge pressure Pd (Mpa). FIG. 6 is a table stored in the memory 11m of FIG. 1 and shows a relationship between the power consumption Wc and the evaporator temperature Te of the compressor 1 and the discharge pressure Pd. As shown in FIG. 6, the discharge pressure Pd increases as the power consumption Wc increases, and the discharge pressure Pd increases as the evaporator temperature Te increases. In FIG. 1, the discharge pressure estimation means 11 estimates the discharge pressure Pd with reference to the table of FIG. 6 based on the input power consumption Wc and the evaporator temperature Te. Further, the discharge pressure estimating means 11 uses the outside air temperature Ta and the compressor rotational speed f as the discharge pressure estimating means 11 so as to remove the influence of the fluctuation of the outside air temperature Ta and the fluctuation of the compression machine point f on the discharge pressure Pd. A signal indicating the corrected discharge pressure Pdc is output to the compressor control means 27 and the expansion valve control means 26.

The compressor control means 27 compares the discharge pressure Pdc estimated by the discharge pressure estimation means 11 with a preset discharge pressure threshold value P0. Then, when the discharge pressure Pdc is greater than the discharge pressure threshold value P0, the compressor control means 27 determines that an abnormal increase in pressure has occurred in the refrigeration cycle apparatus, and stops the compressor 1 to stop the refrigeration cycle apparatus. Stop operation. Further, when the discharge pressure Pdc estimated by the discharge pressure estimation means 11 is equal to or lower than the preset discharge pressure threshold value P0, the compressor control means 27 determines that the discharge pressure Pdc estimated by the discharge pressure estimation means 11 is The compressor 1 is controlled so as to substantially coincide with the predetermined discharge pressure target value.

The function fvhp stored in advance in the memory 21m and the tables stored in advance in the

memories

11m, 23m, and 24m are created in advance by experiments or simulations.

As described above, according to the refrigeration cycle apparatus according to the present embodiment, the compressor current detection means for detecting the current value of the current flowing through the electric motor of the compressor 1 (for example, the compressor current detection in FIG. 10). The compressor power consumption Wc is estimated using the power supply voltage value estimated using the power supply current value IHP detected by the power supply current detection means and the pulse width Dn of the zero cross signal S20 without the need for the means 12). Therefore, without providing a pressure switch, a pressure sensor, and a compressor current detection means, the discharge pressure Pdc can be estimated with the same or higher accuracy as the refrigeration cycle apparatus according to the prior art, and the refrigeration is less expensive than the prior art. A cycle device can be provided. For this reason, it is possible to correctly detect the occurrence of an abnormal increase in the discharge pressure Pdc, stop the operation of the refrigeration cycle apparatus, and prevent the operation at an abnormal pressure exceeding the design pressure.

Further, since the discharge pressure estimating means 11 corrects the discharge pressure Pd using the outside air temperature Tat and the compressor speed f, the discharge pressure is increased even if the outside air temperature Tat and the compressor speed f fluctuate. Can be estimated with accuracy.

(Embodiment 2)
FIG. 7 is a block diagram showing the configuration of the refrigeration cycle apparatus according to Embodiment 2 of the present invention. The refrigeration cycle apparatus according to the present embodiment is different from the refrigeration cycle apparatus according to the first embodiment in that a control unit 18A (control means) is provided instead of the control unit 18. Further, the control unit 18A is different from the control unit 18 in that it includes a power supply voltage estimation unit 21A instead of the power supply voltage estimation unit 21 and further includes a DC voltage detection unit 30. In other respects, the refrigeration cycle apparatus according to the present embodiment is configured and operates in the same manner as the refrigeration cycle apparatus according to the first embodiment, and thus the description thereof is omitted. Only differences from the refrigeration cycle apparatus according to Embodiment 1 will be described below.

In FIG. 7, the DC voltage detection means 30 detects the DC voltage VHPDC after rectifying and smoothing the AC power supply voltage before the operation of the compressor 1, and based on the detected DC voltage VHPDC, The effective value VHPAC (= VHPDC / √2) of the AC power supply voltage before operation is calculated, and a signal indicating the calculated effective value VHPAC of the AC power supply voltage is output to the power supply voltage estimating means 21A.

Similarly to the power supply voltage estimating means 21, the power supply voltage estimating means 21A stores in advance in the memory 21m a function fvhp indicating the relationship between the pulse width Dn of the zero cross signal S20 and the effective value VHP of the AC power supply voltage. . The power supply voltage estimation means 21A corrects the function fvhp using the effective value VHPAC of the AC power supply voltage when the compressor 1 is stopped. FIG. 8 is a graph showing a method for correcting the function fvhp by the power supply voltage estimating means 21A of FIG. In FIG. 8, the power supply voltage estimation means 21A calculates the effective value VHP0 of the AC power supply voltage corresponding to the pulse width Dn of the zero cross signal S20 at the detection timing of the DC voltage VHPDC by the DC voltage detection means 30 using the function fvhp. . Then, the function fvhp is corrected by subtracting the difference value ΔVHP between the effective value VHP0 and the effective value VHPAC from the function fvhp. Therefore, the corrected function fvhpc is expressed by the following equation.

fvhpc = fvhp−ΔVHP = fvhp− (VHP0−VHPAC)

The power supply voltage estimating means 21A uses the corrected function fvhpc instead of the function fvhp, and based on the pulse width Dn of the input zero-cross signal S20, as in the power supply voltage estimating means 21, the effective value VHP of the AC power supply voltage. And a signal indicating the estimated effective value VHP of the AC power supply voltage is output to the compressor power consumption estimation means 25. The function fvhp is not corrected during the operation of the compressor 1 in order to avoid the influence of the power factor correction circuit or the like.

According to the present embodiment, since the function fvhp is corrected and used, the effective value VHP of the AC power supply voltage during the operation of the compressor 1 can be detected with higher accuracy than in the first embodiment. Therefore, the compressor power consumption Wc can be detected with higher accuracy than in the first embodiment, and the discharge pressure estimation means 11 can improve the estimation accuracy of the discharge pressure Pd.

In each of the above embodiments, when the discharge pressure Pdc is greater than the discharge pressure threshold value P0, the compressor control means 27 determines that an abnormal increase in pressure has occurred in the refrigeration cycle apparatus, and stops the compressor 1. Thus, the operation of the refrigeration cycle apparatus is stopped, but the present invention is not limited to this. The compressor control means 27 may reduce the rotation speed of the compressor 1 when the discharge pressure Pdc is larger than the discharge pressure threshold value P0. As a result, even in a transient state such as immediately after the start of the refrigeration cycle apparatus, the abnormal increase in the pressure of the refrigeration cycle apparatus is correctly determined, the rotation speed of the compressor 1 is reduced, and the discharge pressure exceeds the design pressure. Can be suppressed.

Further, the expansion valve control means 26 of the present embodiment may increase the opening degree of the expansion valve 3 when the discharge pressure Pdc is larger than the discharge pressure threshold value P0. Thereby, even in a transient state such as immediately after the start of the refrigeration cycle apparatus, it is possible to correctly determine the occurrence of an abnormal pressure increase, increase the opening of the expansion valve 3, and suppress the abnormal increase in the discharge pressure exceeding the design pressure.

Furthermore, in each of the above embodiments, the refrigerant is carbon dioxide, but the present invention is not limited to this. Preferably, when the compressor 1 is driven, such as R32, carbon dioxide, ethane, ethylene, nitrogen oxide and a mixed refrigerant containing them, the refrigerant circuit 5 is connected to the high pressure side (from the compressor 1 to the expansion valve 3 via the radiator 2). The refrigerant that becomes the supercritical state is used. Thereby, the efficiency of the refrigeration cycle apparatus can be improved. More preferably, carbon dioxide is used as the refrigerant. Thereby, there is no danger of burning even if the refrigerant leaks, and the refrigeration cycle apparatus can be operated safely.

Furthermore, in each of the above-described embodiments, the compressor power consumption estimation means 25 subtracts the blower power consumption value Wf and the control unit power consumption Wp from the refrigeration cycle power consumption WHP (= IHP × VHP). Although the power consumption Wc is estimated, the present invention is not limited to this. When the blower power consumption value Wf and the control unit power consumption Wp are sufficiently smaller than the refrigeration cycle power consumption WHP, the refrigeration cycle power consumption WHP is output to the discharge pressure estimating means 11 as the compressor power consumption Wc. Good. Further, when the blower power consumption value Wf is sufficiently smaller than the refrigeration cycle power consumption WHP, the compressor power consumption Wc is estimated by subtracting only the control unit power consumption Wp from the refrigeration cycle power consumption WHP. Also good. Further, when the control unit power consumption Wp is sufficiently smaller than the refrigeration cycle power consumption WHP, the compressor power consumption Wc is estimated by subtracting only the blower power consumption value Wf from the control unit power consumption Wp. Also good.

In each of the above embodiments, the power source current detection means 19, the blower rotation speed detection means 22, and the compressor rotation speed detection means 28 are provided in the control unit 18 or 18A. However, the present invention is not limited to this. I can't. The power supply current detection means 19, the blower rotation speed detection means 22, and the compressor rotation speed detection means 28 may be provided outside the control unit 18 or 18A.

Further, when the discharge pressure Pdc estimated by the discharge pressure estimation means 11 is equal to or less than a preset discharge pressure threshold value P0, the compressor control means 27 determines that the discharge pressure Pdc estimated by the discharge pressure estimation means 11 is Although the compressor 1 is controlled so as to substantially coincide with the predetermined discharge pressure target value, the present invention is not limited to this. Instead of the compressor control means 27, the expansion valve control means 26 uses the discharge pressure estimation means 11 when the discharge pressure Pdc estimated by the discharge pressure estimation means 11 is equal to or less than a preset discharge pressure threshold value P0. The expansion valve 3 may be controlled so that the estimated discharge pressure Pdc substantially matches a predetermined discharge pressure target value.

As described above, the refrigeration cycle apparatus according to the present invention can estimate the discharge pressure of the refrigerant from the compressor including the supercritical pressure without providing pressure detection means such as a pressure sensor or a pressure switch. The refrigeration cycle apparatus according to the present invention can be applied to a refrigeration cycle apparatus that uses a refrigerant in a supercritical state on the high-pressure side of a refrigerant circuit, such as a heat pump water heater or a hot water heater, and its protection device, and can improve energy efficiency.

DESCRIPTION OF SYMBOLS 1 Compressor 2 Radiator 3 Expansion valve 4 Evaporator 5 Refrigerant circuit 6 Inlet piping 7 Outlet piping 8 Pressure switch 9 Switch means 10 Branch piping 11 Discharge pressure estimation means 12 Compressor current detection means 13 Compressor rotation speed detection means 14 Heat radiation Outlet temperature detection means 15 Evaporator temperature detection means 16 Outside air temperature detection means 17 Blower 18 Control unit 19 Power supply current detection means 20 Zero cross detection means 21 Power supply voltage estimation means 22 Blower rotation speed detection means 23 Blower power consumption estimation means 24 Control section Power consumption estimation means 25 Compressor power consumption estimation means 26 Expansion valve control means 27 Compressor control means 28 Compressor rotation speed detection means 29 Discharge temperature detection means 30 DC voltage detection means

Claims

A refrigerant circuit including an annularly connected compressor, a radiator, an expansion valve, and an evaporator, and circulating a refrigerant;
In a refrigeration cycle apparatus comprising a control means for controlling the refrigerant circuit,
The control means includes
Zero-cross detection means for detecting a zero-cross point of the AC power supply voltage supplied to the refrigeration cycle apparatus and generating a zero-cross signal indicating a period in which the AC power supply voltage is less than zero volts;
Power supply voltage estimating means for estimating an effective value of the AC power supply voltage based on the zero-cross signal;
Based on the current value of the power supply current supplied to the refrigeration cycle apparatus and the estimated effective value of the AC power supply voltage, the power consumption of the refrigeration cycle apparatus is estimated and output as the power consumption of the compressor Compressor power consumption estimating means for
Based on the power consumption of the compressor, the evaporator temperature, which is the temperature of the refrigerant circulating in the evaporator, the outside air temperature, and the rotational speed of the compressor, the discharge pressure of the refrigerant discharged from the compressor Discharge pressure estimating means for estimating
The refrigeration cycle apparatus characterized in that the control means controls the compressor or the expansion valve based on the estimated discharge pressure.
The power supply voltage estimation means uses the relationship between the period length of the period in which the AC power supply voltage is less than zero volts and the effective value of the AC power supply voltage, based on the zero cross signal, to calculate the AC power supply voltage. 2. The refrigeration cycle apparatus according to claim 1, wherein an effective value is estimated.
The control means detects a DC voltage after rectifying and smoothing the AC power supply voltage before operation of the compressor, and based on the detected DC voltage, the AC power supply voltage before operation of the compressor DC voltage detection means for detecting the effective value of
The power supply voltage estimation means uses the effective value of the AC power supply voltage before the operation of the compressor and the period length when the DC voltage is detected, and the period length of the period in which the AC power supply voltage is less than zero volts. And the effective value of the AC power supply voltage is corrected, and the effective value of the AC power supply voltage is estimated using the corrected relationship. .
The discharge pressure estimating means estimates the discharge pressure using the relationship between the estimated power consumption of the compressor and the evaporator temperature and the discharge pressure, and then compresses the estimated discharge pressure to the compression The refrigeration cycle apparatus according to any one of claims 1 to 3, wherein the refrigeration cycle apparatus corrects using the machine rotation speed and the outside air temperature.
The refrigeration cycle apparatus further includes a blower provided to promote evaporation of the refrigerant in the evaporator,
The control means further includes blower power consumption estimation means for estimating the power consumption of the blower based on the rotation speed of the blower,
The compressor power consumption estimation means subtracts the power consumption of the blower from the power consumption of the refrigeration cycle apparatus, and outputs the power consumption after the subtraction as the power consumption of the compressor. The refrigeration cycle apparatus according to any one of 4.
6. The refrigeration cycle apparatus according to claim 5, wherein the control means further includes a blower rotational speed detection means for detecting the rotational speed of the blower and outputting it to the blower power consumption estimation means.
The control means further includes a control unit power consumption estimation means for estimating power consumption of the control means based on a current value of a power supply current supplied to the refrigeration cycle apparatus,
The compressor power consumption estimation means subtracts the power consumption of the control means from the power consumption of the refrigeration cycle apparatus, and outputs the power consumption after the subtraction as the power consumption of the compressor. The refrigeration cycle apparatus according to any one of 1 to 6.
The control means controls the compressor or the expansion valve so that the estimated discharge pressure substantially matches a predetermined discharge pressure target value. The refrigeration cycle apparatus according to any one of the above.
The control means stops the compressor or lowers the rotational speed of the compressor when the estimated discharge pressure is larger than a preset discharge pressure threshold value. The refrigeration cycle apparatus according to any one of 8.
The control means increases the opening of the expansion valve when the estimated discharge pressure is larger than a preset discharge pressure threshold value. The refrigeration cycle apparatus described in 1.
11. The control device according to claim 1, wherein when the compressor is driven, the pressure of the refrigerant is controlled to be a supercritical pressure on a high pressure side of the refrigerant circuit. The refrigeration cycle apparatus described in 1.
12. The refrigeration cycle apparatus according to claim 11, wherein the refrigerant is carbon dioxide.
13. The control means further comprises power supply current detection means for detecting a current value of a power supply current supplied to the refrigeration cycle apparatus and outputting the current value to the compressor power consumption estimation means. The refrigeration cycle apparatus according to any one of the above.
14. The control means according to claim 1, further comprising a compressor rotation speed detection means for detecting the rotation speed of the compressor and outputting it to the discharge pressure estimation means. The refrigeration cycle apparatus described in 1.
15. The refrigeration cycle apparatus according to claim 1, further comprising an evaporator temperature detecting means for detecting the evaporator temperature and outputting the detected temperature to the discharge pressure estimating means.
The refrigeration cycle apparatus according to any one of claims 1 to 15, further comprising an outside air temperature detecting means for detecting the outside air temperature and outputting the detected temperature to the discharge pressure estimating means.