Heat pump hot water system

Abstract

To provide a heat pump hot water system that enables continuous heating operation with stable heating capacity. [Solution] The control device has a determination means 410Gc that determines under predetermined conditions whether or not the power consumption is likely to be high. If the determination means 410Gc determines that the power consumption is likely to be high, the compressor control unit 410B controls the compressor 14 to reduce its rotational speed when the power consumption of the compressor 14 exceeds a third limit value which is less than the second limit value and greater than the first limit value. This allows for power suppression control that corresponds to the variation in power consumption that occurs depending on the installation environment of the heat pump device, making it less likely for the power consumption of the compressor 14 to exceed the third limit value.

Description

Technical Field

[0001] This invention relates to a heat pump water heater that generates hot water by heat exchange with a refrigerant in a water-cooled medium heat exchanger.

Background Art

[0002] Conventionally, in this type of heat pump water heater, as described in Patent Document 1, when an instruction to suppress power consumption in the heat pump device is input, the heat pump device is controlled so as to be below the power consumption upper limit value corresponding to the instruction. Also, when suppressing power consumption, power suppression control is performed so that the power consumption of the heat pump device is below a limit value lower than the power consumption upper limit value at the very limit, and the rotation speed of the compressor is restricted.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] However, since the installation location of the heat pump is determined by the construction contractor as appropriate, if the heat pump unit is installed in a narrow area, wind blows into the heat pump unit, the piping of the heating circulation circuit is long and easily cooled, etc., there is variation in the power consumption (operating power) of the heat pump, and in a situation where the power consumption tends to be high, the rotation speed of the compressor is frequently forced to decrease during the boiling operation, resulting in a significant decrease in the heating capacity of the boiling operation, and at the same time, a surplus in power consumption due to the decrease causes a sharp increase. Repeatedly experiencing this decrease and increase causes hunting in the heating capacity and poses the problem that the boiling operation at maximum capacity cannot be continued.

Means for Solving the Problems

[0005] To solve the above problems, the heat pump device comprises a heat pump device in which a compressor, expansion valve, and air heat exchanger are connected in a ring with refrigerant piping to form a refrigerant circulation circuit; a water-refrigerant heat exchanger that receives refrigerant supplied from the heat pump device via the refrigerant piping and generates hot water to the hot water circulation circuit side by heat exchange with water; a circulation pump that circulates the hot water generated in the water-refrigerant heat exchanger; and a control device that drives the heat pump device to control the heating operation to heat the hot water in the hot water circulation circuit, wherein the control device includes a power suppression determination unit that determines whether or not a power suppression signal instructing the suppression of power consumption in the heat pump device has been input, and when the power suppression determination unit has determined that the power suppression signal has been input In a heat pump hot water system, the control device has a compressor control unit that, when it is determined that a situation is likely to increase power consumption, prohibits an increase in the rotational speed of the compressor if the power consumption of the compressor exceeds a first limit value, and controls the system to reduce the rotational speed of the compressor if the power consumption of the compressor exceeds a second limit value which is greater than the first limit value, the control device has a determination means for determining under predetermined conditions whether or not a situation is likely to increase power consumption, and when the determination means determines that a situation is likely to increase power consumption, the compressor control unit controls the system to reduce the rotational speed of the compressor if the power consumption of the compressor exceeds a third limit value which is less than the second limit value and greater than the first limit value.

[0006] Furthermore, the compressor control unit has a fourth limit value that is smaller than the first limit value, and when the power consumption of the compressor is between the first limit value and the fourth limit value, it limits the rate at which the rotational speed of the compressor increases.

[0007] Furthermore, the control device has a counting means for counting the number of times the rotational speed of the compressor exceeds the second limit value, and the determination means determines that the power consumption is likely to be high if the count is greater than or equal to a predetermined number of times within a predetermined time, and the compressor control unit controls the compressor to reduce its power consumption if the power consumption of the compressor exceeds the limit value.

[0008] Furthermore, if it is determined that the power consumption is likely to be high, and the power consumption of the compressor does not exceed the third limit value within a predetermined duration, the compressor control unit will revert to the control that reduces the rotational speed of the compressor when the power consumption of the compressor exceeds the second limit value. [Effects of the Invention]

[0009] According to this invention, a heat pump hot water system can be provided that performs heating operation with stable heating capacity by performing power suppression control according to the variation in power consumption that occurs depending on the installation environment of the heat pump system. [Brief explanation of the drawing]

[0010] [Figure 1] Schematic diagram of a heat pump hot water system according to one embodiment of the present invention. [Figure 2] Functional block diagram showing the functional configuration of the heating control device. [Figure 3] This diagram shows the control zone for the compressor rotation speed during the first restricted operation when power reduction control is in effect. [Figure 4] This diagram shows the control zone for the compressor rotation speed during the second restricted operation when power reduction control is in effect. [Figure 5] A flowchart illustrating the control procedure performed by the heating control device. [Modes for carrying out the invention]

[0011] Next, one embodiment of the present invention will be described with reference to the drawings.

[0012] <Schematic circuit configuration> As shown in Figure 1, the heat pump hot water system 100 according to this embodiment includes a tank unit 1 having a hot water storage tank 2 for storing hot water, and a heat pump unit 3.

[0013] The heat pump unit 3 includes a water-refrigerant heat exchanger 15 for heating the hot water in the hot water storage tank 2, and a heating circulation pump 19. The water-refrigerant heat exchanger 15 has a refrigerant-side flow path 15b for circulating the refrigerant and a water-side flow path 15a, and exchanges heat between the high-temperature, high-pressure refrigerant and the hot water in the hot water storage tank 2. That is, the water-side flow path 15a of the water-refrigerant heat exchanger 15 and the hot water storage tank 2 are connected in a ring by a heating supply pipe 5 and a heating return pipe 6, forming a heating circulation circuit 4 as a hot water circulation circuit spanning the tank unit 1 and the heat pump unit 3.

[0014] The heating supply pipe 5 is connected to the lower part of the hot water storage tank 2, and the heating return pipe 6 is connected to the upper part of the hot water storage tank 2. The heating circulation pump 19 is installed in the middle of the heating supply pipe 5 and circulates the hot water in the hot water storage tank 2 while circulating the hot water from the heating supply pipe 5 to the heating return pipe 6 via the water-side flow path 15a. The heating supply pipe 5 is equipped with an inlet water temperature sensor 23 that detects the inlet water temperature T1 flowing into the water-side flow path 15a of the water-refrigerant heat exchanger 15, and the heating return pipe 6 is equipped with a boiling temperature sensor 24 that detects the boiling temperature Tb flowing out from the water-side flow path 15a toward the hot water storage tank 2.

[0015] In the tank unit 1, multiple hot water temperature sensors 12 are provided on the side of the hot water storage tank 2, extending vertically to detect the temperature Tw of the hot water inside the storage tank 2. A water supply pipe 7 is connected to the lower part of the hot water storage tank 2 to supply water to the tank, and a hot water outlet pipe 8 is connected to the upper part of the hot water storage tank 2 to dispense the hot water stored inside. The hot water outlet pipe 8 has a negative pressure intake function that opens to introduce air into the hot water storage tank 2 when negative pressure is created inside the tank, and a pressure relief valve 119 is provided that opens to release pressure when the pressure inside the tank exceeds the opening pressure. A water supply bypass pipe 9 branches off from the water supply pipe 7. The pressure relief valve 119 is equipped with a manual lever (not shown) for manually opening it. Furthermore, the system includes a mixing valve 10 that mixes hot water from the outlet pipe 8 with cold water from the water supply bypass pipe 9 to produce hot water at the set temperature, a hot water supply pipe 108a for supplying the hot water mixed by the mixing valve 10 to the hot water supply terminal 125, and a hot water temperature sensor 11 for detecting the hot water temperature in the hot water supply pipe 108a.

[0016] The heat pump unit 3 also includes a compressor 14 for compressing the refrigerant, an electronic expansion valve 16 as a pressure reducer for reducing the pressure of the refrigerant after it has passed through the water-refrigerant heat exchanger 15, an air heat exchanger 17 as a heat source-side heat exchanger for heat exchange between the air as a heat source and the refrigerant, and an outdoor fan 60 for supplying outside air to the air heat exchanger 17. The compressor 14, the refrigerant-side flow path 15b of the water-refrigerant heat exchanger 15 through which the refrigerant discharged from the compressor 14 flows, the electronic expansion valve 16, and the air heat exchanger 17 are connected in a ring shape by refrigerant piping 18 to form a refrigerant circulation circuit 30.

[0017] The refrigerant piping 18 connects the discharge side of the compressor 14 to the inlet side of the water refrigerant heat exchanger 15, and the suction side of the compressor 14 to the outlet side of the air heat exchanger 17. The refrigerant piping 18 and the compressor 14, air heat exchanger 17, and electronic expansion valve 16 connected thereto constitute a heat pump device. In this embodiment, the heat pump unit 3, including the compressor 14, and the tank unit 1 that constitute the heat pump device are not provided with a dedicated power supply. Both the heat pump unit 3 and the tank unit 1 are configured to operate by receiving power from an external power supply, such as a household power supply or a storage battery that provides AC100V.

[0018] In the refrigerant circulation circuit 30, for example, R32 refrigerant is used as the refrigerant, which constitutes a heat pump cycle. A discharge temperature sensor 20 for detecting the discharge temperature Tout of the refrigerant discharged from the compressor 14 is provided at a portion on the discharge side of the compressor 14 in the refrigerant pipe 18. An outflow temperature sensor 21 for detecting the outflow temperature T2 (the outlet temperature of the refrigerant) of the refrigerant flowing out from the refrigerant-side flow path 15b and heading toward the electronic expansion valve 16 is provided in the refrigerant pipe 18 between the refrigerant-side flow path 15b and the electronic expansion valve 16. An outside air temperature sensor 22 for detecting the outside air temperature Tair is provided on the air inlet side of the air heat exchanger 17.

[0019] And the tank unit 1 is provided with a hot water supply control device 40 to which the detection results of the hot water supply temperature sensor 11 and the stored hot water temperature sensor 12 are input. Similarly, the heat pump unit 3 is provided with a heating control device 50 to which the detection results of the discharge temperature sensor 20, the outflow temperature sensor 21, the outside air temperature sensor 22, the water inlet temperature sensor 23, and the boiling temperature sensor 24 are input. The heating control device 50 and the hot water supply control device 40 are connected to be communicable with each other, and based on the detection results of the hot water supply temperature sensor 11, the stored hot water temperature sensor 12, the discharge temperature sensor 20, the outflow temperature sensor 21, the outside air temperature sensor 22, the water inlet temperature sensor 23, the boiling temperature sensor 24, etc., while cooperating with each other, they control the operations of the respective devices in the tank unit 1 and the heat pump unit 3.

[0020] Note that there is a master-slave relationship in control between the heating control device 50 and the hot water supply control device 40. For example, the hot water supply control device 40 outputs an operation command and a power suppression signal (described later) based on the detection results of the hot water supply temperature sensor 11 and the stored hot water temperature sensor 12 to the heating control device 50, and the heating control device 50 controls the operations of the respective devices in the heat pump unit 3 based on this operation command and power suppression signal and the detection results of the discharge temperature sensor 20, the outflow temperature sensor 21, the outside air temperature sensor 22, the water inlet temperature sensor 23, and the boiling temperature sensor 24. Hereinafter, in this specification, such a case will be taken as an example for explanation.

[0021] <Heat pump input voltage and current detection device> The heat pump unit 3 is equipped with a heat pump input voltage detection device 210 and a heat pump input current detection device 220, which use known sensors to detect the voltage and current values ​​input to the heat pump unit 3 from an external power source. The input voltage values ​​detected by the heat pump input voltage detection device 210 and the input voltage values ​​detected by the heat pump input current detection device 220 are output to the heating control device 50, respectively.

[0022] Furthermore, the heat pump unit 3 is equipped with a heat pump power consumption detection device 200 that detects the HP power consumption, which is the power consumed within the heat pump unit 3. The heat pump power consumption detection device 200 calculates the HP power consumption by integrating the voltage value detected by the heat pump input voltage detection device 210 and the current value detected by the heat pump input current detection device 220. The calculated HP power consumption is output to the heating control device 50. Although "power consumption" is used to describe the power consumed by the equipment, "operating power" has the same meaning as "power used by the equipment."

[0023] <Heating control device> Next, the heating control device 50 provided in the heat pump unit 3 will be described. Although detailed illustrations are omitted, the heating control device 50 includes a storage unit for storing various data and programs, and a control unit for performing calculation and control processing. The functional configuration of this heating control device 50 will be explained with reference to Figure 2.

[0024] As shown in Figure 2, the heating control device 50 functionally includes an operation switching unit 410A, a compressor control unit 410B, an expansion valve control unit 410C, an outdoor fan control unit 410D, a pump control unit 410F, and a power control unit 410G (corresponding to a power suppression determination unit 410Ga, a release value setting unit 410Gb, a determination means 410Gc, and a counting means 410Gd).

[0025] The operation switching unit 410A receives operation commands and power suppression signals (details described later) output by the hot water storage control device 40. In response to the operation commands, the operation switching unit 410A decides whether or not to perform the boiling operation described later, in which the air heat exchanger 17 functions as an evaporator in the heat pump unit 3. The operation switching unit 410A also outputs operation information corresponding to the decision result to the compressor control unit 410B, expansion valve control unit 410C, outdoor fan control unit 410D, and pump control unit 410F. This operation information includes the temperature Tw of the hot water in the hot water storage tank 2 detected by the hot water storage temperature sensor 12, and the target boiling temperature Tbo, which is determined as appropriate.

[0026] In this example, the compressor control unit 410B receives the outside air temperature Tair detected by the outside air temperature sensor 22, operation information corresponding to the operation command of the hot water storage control device 40, and the HP input current value from the heat pump input current detection device 220 (these may be input directly or indirectly; the same applies hereinafter). The compressor control unit 410B also receives the determination result from the power suppression determination unit 410Ga, described later, and the current release value from the release value setting unit 410Gb. The compressor control unit 410B also includes a reference rotation speed setting unit 410Bb and a target rotation speed determination unit 410Bc.

[0027] The reference rotation speed setting unit 410Bb determines the maximum value (reference rotation speed) of the target rotation speed of the corresponding compressor 14 based on the ambient temperature Tair detected by the ambient temperature sensor 22 and the target boiling temperature Tbo, and controls the compressor 14 at the reference rotation speed when it is started up. In addition, as the boiling operation continues, the load on the compressor 14 increases and the HP power consumption rises.

[0028] During power suppression control, the target rotation speed determination unit 410Bc sets a limit rotation speed (target rotation speed corresponding to HP power consumption) smaller than the target reference rotation speed of the compressor 14, based on the input ambient temperature Tair, target boiling temperature Tbo, power suppression signal, the determination result of the power suppression determination unit 410Ga, and the current release value, within the range of reference rotation speeds, so that the HP power consumption, which fluctuates according to the load, does not exceed the power consumption upper limit. The unit then increases or decreases the rotation speed of the compressor 14 to keep it below this limit rotation speed (in detail, the motor that rotates the compressor 14 is controlled so that the current consumption does not exceed the limit value described later).

[0029] In this example, the power control unit 410G receives the HP input voltage value from the heat pump input voltage detection device 210, the power suppression signal from the hot water storage control device 40, and the HP power consumption from the heat pump power consumption detection device 200. The power control unit 410G also includes a power suppression determination unit 410Ga and a release value setting unit 410Gb.

[0030] The release value setting unit 410Gb sets the current release value based on the HP input voltage value detected by the heat pump input voltage detection device 210. The set current release value is output to the target rotational speed determination unit 410Bc of the compressor control unit 410B. The power suppression determination unit 410Ga will be described later.

[0031] In this example, the expansion valve control unit 410C receives the following inputs: the boiling temperature Tb detected by the boiling temperature sensor 24, the refrigerant discharge temperature Tout detected by the discharge temperature sensor 20, the refrigerant discharge temperature T2 detected by the discharge temperature sensor 21, the ambient temperature Tair detected by the ambient temperature sensor 22, the inlet water temperature T1 detected by the inlet water temperature sensor 23, operation information corresponding to the operation command of the hot water storage control device 40, a power suppression signal from the hot water storage control device 40, and the HP input voltage value from the heat pump input voltage detection device 210. The expansion valve control unit 410C also has a target opening degree determination unit 410Cb.

[0032] The target opening determination unit 410Cb determines the target opening of the pressure reducer such that the state value of the refrigerant on the high-pressure side satisfies predetermined target value conditions. Specifically, in this example, the target opening determination unit 410Cb determines the target opening of the electronic expansion valve 16 such that the temperature difference Tout-T2 (corresponding to the state value of the refrigerant on the high-pressure side) between the refrigerant discharge temperature Tout and the refrigerant outflow temperature T2 becomes a predetermined target temperature difference ΔH (corresponding to predetermined target value conditions) calculated based on the target boiling temperature Tbo and the inlet water temperature T1 (= ΔH control).

[0033] The outdoor fan control unit 410D is equipped with a set rotation speed determination unit 410Db, which controls the rotation speed of the outdoor fan 60.

[0034] The set rotation speed determination unit 410Db receives the outside air temperature Tair detected by the outside air temperature sensor 22 and operation information corresponding to the operation command of the hot water storage control device 40. The outdoor fan control unit 410D determines the target set rotation speed of the outdoor fan 60 based on the input operation information and the outside air temperature Tair, and controls the rotation speed of the outdoor fan 60 to reach that set rotation speed.

[0035] The pump control unit 410F receives the boiling temperature Tb detected by the boiling temperature sensor 24 and operation information corresponding to the operation command from the hot water storage control device 40, and controls the rotation speed of the heating circulation pump 19 based on these.

[0036] <Water heating operation> As described above, in the heat pump unit 3 of this embodiment, the discharge side of the compressor 14 is connected to the inlet side of the water-refrigerant heat exchanger 15, and the suction side of the compressor 14 is connected to the outlet side of the air heat exchanger 17. This causes the air heat exchanger 17 to function as an evaporator that evaporates the low-temperature, low-pressure refrigerant from the electronic expansion valve 16. In other words, heat is released in the water-refrigerant heat exchanger 15 by heat dissipation from the refrigerant in the refrigerant piping 18, and hot water is generated in the heating circulation circuit 4. The generated hot water is supplied to the hot water storage tank 2 via the heating return pipe 6 by the flow of hot water in the heating circulation circuit 4 induced by the heating circulation pump 19, thereby raising the temperature of the hot water in the hot water storage tank 2.

[0037] <Power suppression control and release control> Here, as described above, when the compressor 14 of the heat pump unit 3 operates by receiving power from a household power supply or storage battery, the limited power capacity is shared with the tank unit 1 and various household electrical appliances. Therefore, in this embodiment, a power suppression signal instructing the suppression of power consumption (power usage) in the compressor 14 is input from the hot water storage control device 40 to the expansion valve control unit 410C and power control unit 410G of the heating control device 50. The power suppression signal indicates a limit value (limit value < upper limit value of power consumption) that is permissible for the compressor 14 to consume.

[0038] As described above, the power control unit 410G is equipped with a power suppression determination unit 410Ga. This power suppression determination unit 410Ga determines whether or not a power suppression signal has been input. If it is determined that a power suppression signal has been input, the power suppression determination unit 410Ga outputs the value of the power consumption upper limit specified by the power suppression signal to the target rotational speed determination unit 410Bc of the compressor control unit 410B. Although not shown in the diagram, the determination result from this power suppression determination unit 410Ga is also output to the expansion valve control unit 410C. As mentioned above, the current release value based on the HP input voltage value detected by the heat pump input voltage detection device 210 is output from the release value setting unit 410Gb to the target rotation speed determination unit 410Bc of the compressor control unit 410B.

[0039] The target rotational speed determination unit 410Bc of the compressor control unit 410B controls the compressor at a rotational speed less than or equal to the reference rotational speed set by the reference rotational speed setting unit 410Bb, and compares the HP power consumption input from the heat pump power consumption detection device 200 with the power consumption upper limit value from the power suppression determination unit 410Ga, thereby increasing or decreasing the limit rotational speed of the compressor 14 so that the HP power consumption does not exceed the power consumption upper limit value, and sets the limit rotational speed of the compressor 14 (= power suppression control). In addition, if the HP input current value from the heat pump input current detection device 220 exceeds the current release value input from the release value setting unit 410Gb, the target rotational speed determination unit 410Bc sets the target rotational speed of the compressor 14 lower than before the exceedance (= release control).

[0040] The target rotational speed determination unit 410Bc controls the rotational speed of the compressor 14 by increasing or decreasing it according to the difference between the HP power consumption and the power limit, as described above. In other words, if the difference between the power consumption limit and the HP power is large (power consumption limit > HP power consumption), the rotational speed of the compressor 14 is increased.

[0041] <Potential effects during power reduction control> As described above, when power suppression control is performed, the compressor control unit 410B limits the rotational speed of the compressor 14 so that the HP power consumption remains within the power consumption upper limit. If the HP power consumption exceeds the power consumption upper limit, the compressor 14 will be stopped. Therefore, if it exceeds a second limit A2 which is lower than the power consumption upper limit, the rotational speed of the compressor 14 is reduced, and the rotational speed of the compressor 14 is controlled to stay within the second limit A2.

[0042] Furthermore, when the rotational speed of the compressor 14 is limited and decreases, the refrigerant temperature on the high-pressure side of the refrigerant piping 18 tends to decrease. To maintain this, the expansion valve control unit 410C narrows the opening of the electronic expansion valve 16.

[0043] <First restricted boiling operation> During power suppression control, the HP power consumption input from the heat pump power consumption detection device 200 is controlled to be less than or equal to the limit rotational speed corresponding to the second limit value A2 from the power suppression determination unit 410Ga. As a result, the rotational speed of the compressor 14 becomes lower than the reference rotational speed at the start of the boiling operation, and the system switches to the first limited boiling operation, which is performed with a lower boiling temperature.

[0044] Furthermore, during power suppression control, the rotational speed of the compressor 14 is controlled to be below the limit rotational speed, but not below the minimum rotational speed (in this case, 30 rps). In other words, the rotational speed of the compressor 14 is controlled by limiting rotational speed [rps] ≥ compressor rotational speed [rps] ≥ minimum rotational speed [rps]. If the rotational speed of the compressor 14 falls below the minimum rotational speed, stable heating operation cannot be performed, resulting in the heating operation stopping or the heating temperature range becoming narrow, making it impossible to store enough hot water in the hot water storage tank 2.

[0045] Next, regarding the control of the compressor 14 during the first limited boiling operation under power suppression control, the control zones for the rotational speed of the compressor 14 will be explained based on Figure 3. In power suppression control, the rotational speed of the compressor 14 is controlled based on the control zones shown in Figure 3. The rotational speed of the compressor 14 is controlled based on whether the power consumption (power usage) of the compressor 14 is in area A (forced reduction), area B (increase prohibited), or area C (normal control). As shown in Figure 3, each control zone is configured to have a first limit value (A1) and a second limit value (A2).

[0046] When the current rises, if the power consumption of the compressor 14 is less than the first limit A1, it is in region C and normal control is performed. If the power consumption of the compressor 14 exceeds the first limit A1, it enters region B and the increase in power consumption is prohibited. If the power consumption of the compressor 14 exceeds the second limit A2, it enters region A and the power consumption is forcibly reduced.

[0047] When the current decreases, if the power consumption of the compressor 14 exceeds the second limit value A2 of the compressor 14, the system enters region A and forcibly reduces the rotational speed of the compressor 14. When the power consumption of the compressor 14 becomes less than the second limit value A2, the system enters region B and prevents further increases in power consumption. When the power consumption of the compressor 14 becomes less than the first limit value A1, the system enters region C and performs normal control.

[0048] Furthermore, based on the control zone for the rotational speed of the compressor 14 in Figure 3, the highest possible boiling temperature can be achieved by performing the boiling operation so that the rotational speed of the compressor 14 is below the second limit value.

[0049] However, if the heat pump unit 3 is located in a confined space, if air blows into the inside of the heat pump unit 3, or if the piping of the heating circulation circuit 4 is long and cools down easily, the power consumption of the HP will vary, and power consumption will tend to be high. In such situations, the system will frequently enter region A during the boiling operation, forcing a decrease in the rotational speed of the compressor 14. At the same time, the reduced rotational speed will create a margin in power consumption, causing a rapid increase in the rotational speed of the compressor 14. This repeated decrease and increase results in hunting in the heating capacity and makes it impossible to continue boiling operation at maximum capacity.

[0050] Therefore, in this embodiment, when power consumption tends to be high, a second limited heating operation, which is different from the first limited heating operation, is implemented.

[0051] <Second restricted boiling operation> In the second limited boiling operation, the compressor 14 is controlled according to the control zone shown in Figure 4. In the second-limit heating operation, when power consumption tends to be high during power suppression control, if the HP power consumption input from the heat pump power consumption detection device 200 exceeds the third limit value A3, which is lower than the second limit value A2 and higher than the first limit value A1, the rotational speed of the compressor 14 is reduced.

[0052] Furthermore, in the second limited heating operation, if the situation is such that power consumption tends to be high, and the HP power consumption input from the heat pump power consumption detection device 200 exceeds the fourth limit value A4, which is lower than the first limit value A1, the rate at which the rotational speed of the compressor 14 increases will be limited.

[0053] Regarding the limit on the rate of increase, one method is to set an upper limit on the increase in the rotational speed of the compressor 14 per hour. For example, in region C of the second limited boiling operation, the compressor rotational speed that can be increased per minute is set to 3 rps, and in region D of the second limited boiling operation, the rotational speed of the compressor 14 that can be increased per minute is limited to 0.2 rps, thereby suppressing a rapid increase in the rotational speed of the compressor 14.

[0054] Next, regarding the control of the compressor 14 during the second limited boiling operation under power suppression control, the control zones for the rotational speed of the compressor 14 will be explained based on Figure 4. In power suppression control, the rotational speed of the compressor 14 is controlled based on the control zones shown in Figure 4. The rotational speed of the compressor 14 is controlled based on whether the HP power consumption (power usage) of the compressor 14 is in area A (forced reduction), area B (increase prohibited), area D (increase speed limit), or area C (normal control). As shown in Figure 4, each control zone is configured to have a third limit value (A3), a first limit value (A1), and a fourth limit value (A4).

[0055] When the current rises, if the power consumption of the compressor 14 is less than the fourth limit A4, it is in region C and normal control is performed. If the power consumption of the compressor 14 exceeds the fourth limit A4, it enters region D and the rate of increase in power consumption is limited. If the power consumption of the compressor 14 exceeds the first limit A1, it enters region B and the increase in power consumption is prohibited. If the power consumption of the compressor 14 exceeds the third limit A3, it enters region A and the power consumption is forcibly reduced.

[0056] When the current decreases, if the power consumption of the compressor 14 exceeds the third limit value A3 of the compressor 14, it enters region A and the rotational speed of the compressor 14 is forcibly reduced. When the power consumption of the compressor 14 becomes less than the third limit value A3, it enters region B and the increase in power consumption is prohibited. When the power consumption of the compressor 14 becomes less than the first limit value A1, it enters region D and the rate of increase is limited. When it becomes less than the fourth limit value A4, it enters region C and normal control is performed.

[0057] In this way, by switching to a second-limit boiling operation in which the rotational speed of the compressor 14 is controlled to correspond to a third limit A3, which is lower than the second limit A2 and higher than the first limit A1, it is possible to control the unit at a third limit A3, which is lower than the second limit A2, rather than controlling it in a situation where the installation environment of the heat pump unit 3 is poor and it is likely to exceed the second limit A2 and enter region A. This stabilizes the heating capacity and allows the boiling operation to continue.

[0058] Furthermore, by setting a fourth limit value A4 that is lower than the first limit value A1, and establishing a region D between the first limit value A1 and the fourth limit value A4 for limiting the rate at which the compressor 14's rotational speed increases, if the compressor 14 is forced to decrease due to the power consumption of the compressor 14 exceeding the third limit value A3 and enters region C, the power consumption of the compressor 14 will increase sharply due to the resulting margin in power consumption. However, the rate at which the power consumption increases is limited in region D, which suppresses the sharp increase in power consumption and prevents the heating capacity from hunting by allowing it to return to region A.

[0059] Furthermore, by ensuring that the power consumption of the compressor 14 is below the third limit value and by limiting the rising speed in region D, the heating capacity can be stabilized near region B, where the boiling temperature can be raised to its highest level.

[0060] <Judgment method> The heating control device 50 is provided with a determination means 410Gc that determines under predetermined conditions whether or not the power consumption is likely to be high, and a counting means 410Gd that starts counting on a timer when the rotational speed of the compressor 14 exceeds the second limit value A2 and enters region A during the first limited boiling operation, and counts the time until the rotational speed of the compressor 14 exceeds the second limit value A2 and enters region A again. In this embodiment, the predetermined condition is whether the number of times the power consumption exceeds the second limit value A2 within a predetermined time during the first limit heating operation is greater than or equal to a predetermined number of times, and specifically, whether the count counted by the counting means 410Gd is less than a predetermined time (in this case, less than 30 minutes).

[0061] In other words, the determination means 410Gc determines that if the count measured by the counting means 410Gd is less than a predetermined time, the power consumption is likely to be high, and if the count measured by the counting means 410Gd is longer than the predetermined time, the determination means 410Gc determines that the power consumption is not likely to be high.

[0062] Furthermore, during the second-restricted boiling operation, if the determination means 410Gc determines that the predetermined release conditions have been met, it determines that the situation is no longer one in which power consumption is likely to be high. Then, the operation switching unit 410 returns the second-restricted boiling operation to the first-restricted boiling operation. If the power suppression control is released during the second-restricted boiling operation, the operation switching unit 410 returns to normal boiling operation. Here, the predetermined release condition is whether the counting means 410Gd has counted the duration during which the third limit value A3 has not been exceeded since switching to the second limit boiling operation, and whether a predetermined duration (in this case, 8 hours) has been counted. The determination means 410Gc determines that the predetermined release condition has been met if the duration exceeds the predetermined duration, and the operation switching unit 410 switches from the second limit boiling operation to the first limit boiling operation.

[0063] <Control Procedure> To realize the above method, the control procedure performed by the heating control device 50 of this embodiment will be explained with reference to the flowchart in Figure 5.

[0064] In Figure 5, first, in S1, it is confirmed whether or not the operation switching unit 410A has received an instruction to start the boiling operation (S1). If the operation switching unit 410A has received an instruction to start the boiling operation (S1 is Yes), the outside air temperature sensor 22 detects the outside air temperature Tair (S2). Based on the detected outside air temperature Tair and the target boiling temperature Tbo, the compressor control unit 410B determines the reference rotational speed of the compressor 14, and the outdoor fan control unit 410D determines the set rotational speed of the outdoor fan 60 (S3).

[0065] The heating control device 50 controls the compressor 14 and the outdoor fan 60 at the rotational speed determined in S3, and controls the heating circulation pump 19 and the electronic expansion valve 16 at their initial opening and initial rotational speeds to start normal boiling operation (boiling operation without restrictions due to power suppression control) (S4).

[0066] During the heating operation, based on the determination result by the power reduction determination unit 410Ga, it is checked whether a power reduction signal has been input from the hot water storage control device 40 and whether power reduction control has been instructed (S5). If power reduction control has been instructed (S5 is Yes), the compressor control unit 410B reduces the rotational speed of the compressor 14 according to the power consumption of the compressor 14 (S6), and the heating control device 50 switches to first limited heating operation (S7). The power reduction control of the compressor 14 here is based on the control zones shown in Figure 3.

[0067] When the first limited boiling operation is being performed (S7), the determination means 410Gc monitors whether predetermined conditions are met (S8). The predetermined condition here is that if the count measured by the counting means 410Gd during the first limited heating operation is less than a predetermined time (in this case, less than 30 minutes), it is determined that the power consumption is likely to be high.

[0068] In S8, if the determination means 410Gc determines that the situation is not one in which power consumption is likely to increase (S8 is Yes), the first limited boiling operation is continued. Then, the process proceeds to S9, where the power suppression determination unit 410Ga checks whether the power suppression control has ended and whether there is an instruction to release the power suppression control (S9). If there is an instruction to release the power suppression control (S9 is No), the operation switching unit 410A switches the first restricted boiling operation to normal boiling operation with the power restriction released and returns to S5. If the power suppression control remains in effect (S9 is Yes), the process proceeds to S10.

[0069] The operation switching unit 410A determines whether or not a stop command for the heating operation has been issued by the hot water storage control device 40 (S10). If a stop command has been issued (S10 is Yes), the flowchart in Figure 5 is terminated.

[0070] Furthermore, if the determination means 410Gc determines in S8 that the power consumption is likely to be high (S8 is No), the compressor control unit 410B controls the compressor 14 to be less than or equal to the third limit value A3 (S11) and switches to the second limit boiling operation (S12). The power suppression control of the compressor 14 here is controlled based on the control zones in Figure 4.

[0071] After the second limited boiling operation is started, the determination means 410Gc monitors whether the predetermined release conditions for the second limited boiling operation are met (S13). Here, the counting means 410Gd counts the duration during which the power consumption of the compressor 14 does not exceed the third limit value A3. If the determination means 410Gc determines that the time counted by the counting means 410Gd has exceeded a predetermined duration (S13 is No), the operation switching unit 410A switches from the second limit boiling operation to the first limit boiling operation (S6). Furthermore, if the determination means 410Gc determines that the time during which the rotational speed of the compressor 14 does not exceed the third limit value A3 does not exceed a predetermined duration (S13 is Yes), it continues the second limit boiling operation and proceeds to S14.

[0072] Next, it is checked whether power suppression control is continuing (S14). If power suppression control is continuing (S14 is Yes), the second-limit boiling operation continues and the process proceeds to S15. Furthermore, if power suppression control has ended (S14 is No), the operation switching unit 410A terminates the second-restricted boiling operation, switches to normal boiling operation with the power restriction removed, and returns to S5.

[0073] Next, the operation switching unit 410A checks whether a stop command for the heating operation has been issued by the hot water storage control device 40 (S15). If a stop command is issued (S15 is Yes), the flowchart in Figure 5 is terminated. If no stop command is issued (S15 is No), the second limited heating operation is continued, and the process returns to S13.

[0074] Furthermore, in S6, if there is no power suppression control during the heating operation (S5 is No), the normal heating operation continues, and when the heating operation is stopped by an operation command from the hot water storage control device 40 (S16 is Yes), the heating operation ends, and the flowchart in Figure 5 ends.

[0075] In this way, by providing a determination means 410Gc that switches control zones depending on whether or not the situation is likely to increase power consumption, it is possible to switch to power suppression control according to the installation environment of the heat pump unit 3.

[0076] Furthermore, in situations where power consumption tends to be high, the system controls the rotational speed of the compressor 14 to correspond to a third limit A3, which is lower than the second limit A2 and higher than the first limit A1, based on the HP power consumption input from the heat pump power consumption detection device 200. Additionally, a region D for limiting the rate of increase of the rotational speed of the compressor 14 is provided between the first limit A1 and the fourth limit A4. This suppresses hunting caused by a decrease in the rotational speed of the compressor 14 due to the influence of the installation environment of the heat pump unit 3, enabling stable heating operation.

[0077] It should be noted that the present invention is not limited to the embodiments, and modifications are permitted without changing the gist of the invention. For example, in this embodiment, the determination means 410Gc starts counting the timer when the rotational speed of the compressor 14 exceeds the second limit value A2 and enters region A during the first limited boiling operation, and the counting means 410Gd counts the time until the rotational speed of the compressor 14 exceeds the second limit value A2 and enters region A again. If the count counted by the counting means 410Gd is less than a predetermined time (in this case, less than 30 minutes), it is determined that the power consumption is likely to be high. However, for example, when the rotational speed of the compressor 14 exceeds the second limit value A2 and enters region A during the first limited boiling operation, it may also be determined whether the power consumption is likely to be high based on whether the difference between the power consumption value and the second limit value A2 is greater than or equal to a predetermined difference. Furthermore, during the first limited boiling operation, if the rotational speed of the compressor 14 exceeds the second limit value A2 and enters region A, the time from when the rotational speed of the compressor 14 is controlled to decrease until it enters region B can be compared with a predetermined decrease time to determine whether the power consumption is likely to increase or not, based on whether the decrease time is greater than or less than the predetermined decrease time.

[0078] Furthermore, while this embodiment controls the compressor 14 so that its power consumption (power usage) does not exceed a limit, power suppression control is not limited to the power consumption (power usage) of the compressor 14. For example, power suppression control may be performed by comparing the current consumption of the compressor 14, which is the current value before it is converted to power consumption, with the limit, or by comparing the apparent power usage of the compressor 14, which is calculated using the apparent power that combines active power and reactive power, with the limit. [Explanation of Symbols]

[0079] 1 Tank Unit 2. Hot water storage tank 3. Heat pump unit 4 Heating circulation circuit (hot water circulation circuit) 5. Heating supply tube 6. Heating return tube 14 Compressor 15 Water refrigerant heat exchanger 16 Electronic expansion valve 17. Air heat exchanger 18 Refrigerant Piping 19. Heating circulation pump 22 Outdoor temperature sensor 30 Refrigerant circulation circuit 40. Hot water storage control device 50 Heating control device (control device) 60 Outdoor fan 100 Heat pump hot water system 210 Heat pump input voltage detection device 220 Heat pump input current detection device 410B Compressor Control Unit 410C Expansion Valve Control Unit 410G Power Control Unit 410Gc Judgment means 410Gd counting method Tair outside temperature

Claims

1. A heat pump system in which a compressor, expansion valve, and air heat exchanger are connected in a ring with refrigerant piping to form a refrigerant circulation circuit, A water-refrigerant heat exchanger receives a refrigerant supply from the heat pump device via the refrigerant piping and generates hot water for the hot water circulation circuit side through heat exchange with water, A circulation pump for circulating the hot water generated in the aforementioned water-refrigerant heat exchanger, The system includes a control device that drives the heat pump device to control the heating operation for heating the hot water in the hot water circulation circuit, The control device is A power reduction determination unit that determines whether or not a power reduction signal instructing the heat pump device to reduce power consumption has been input, A heat pump hot water system having a compressor control unit which, when the power suppression determination unit determines that the power suppression signal has been input, prohibits an increase in the rotational speed of the compressor if the power consumption of the compressor exceeds a first limit value, and controls the rotational speed of the compressor to decrease if the power consumption of the compressor exceeds a second limit value which is greater than the first limit value, The control device has a determination means for determining whether or not the power consumption is likely to be high under predetermined conditions. If the determination means determines that the situation is likely to result in high power consumption, The heat pump hot water system is characterized in that the compressor control unit controls the rotational speed of the compressor to decrease when the power consumption of the compressor exceeds a third limit value which is less than the second limit value and greater than the first limit value.

2. Having a fourth limit value smaller than the first limit value, The heat pump hot water device according to claim 1, characterized in that the compressor control unit limits the rate at which the rotational speed of the compressor increases when the power consumption of the compressor is between the first limit value and the fourth limit value.

3. The control device has a counting means for counting the number of times the rotational speed of the compressor exceeds the second limit value. The determination means uses the condition that the count occurs at least once within a predetermined time, The heat pump hot water system according to claim 1 or 2, characterized in that, when it is determined that a situation is likely to result in high power consumption, the compressor control unit controls the compressor to reduce power consumption if the power consumption of the compressor exceeds the limit value.

4. In cases where it is determined that power consumption is likely to be high, if the power consumption of the compressor does not exceed the third limit value within a predetermined duration, the compressor control unit returns to the control that reduces the rotational speed of the compressor when the power consumption of the compressor exceeds the second limit value, as described in claim 3.

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