JP7410380B2 - water heater - Google Patents

Description

The present invention relates to a water heater equipped with a heat pump.

In recent years, an increasing number of users are installing private power generation systems such as solar power generation systems. Patent Document 1 describes a configuration in which a private power generation system (for example, a solar power generation system) is interconnected with a commercial power grid to supply power to domestic electrical equipment (for example, a water heater). Furthermore, in the case of a private power generation system, the electric power generated by the private power generation system can be supplied to electrical equipment in the event of a power outage in the commercial power system.

Furthermore, recently, the number of users installing household storage batteries has been increasing. A household storage battery is a storage battery unit that includes a storage battery and an inverter that converts DC power of the storage battery into AC power and outputs it. By installing such a storage battery unit, a water heater equipped with a heat pump can be operated by supplying power from the storage battery during a power outage in the commercial power system.

Patent No. 5853766

However, since the storage capacity of popular storage battery units (home storage batteries) is approximately several kWh, there is a problem that when a water heater equipped with a conventional heat pump is operated normally, the electricity in the storage battery is consumed in a short period of time. There is.

Therefore, the storage battery unit and the water heater are configured to be able to communicate with each other, and the storage battery unit notifies the water heater that the storage battery is being used (that power is being supplied from the storage battery). It has also been proposed that the device perform a save operation that suppresses power consumption. However, in this case, it is necessary to have a configuration for communication, which is disadvantageous in terms of manufacturing costs, construction, etc.

The present invention has been made in order to solve the above-mentioned problems, and it is possible to reduce power consumption when the power of a storage battery is being used, without acquiring information on the fact that it is being used from outside. The purpose is to provide a water heater that can be operated.

In order to achieve the above object, a water heater according to an aspect of the present invention includes a heat pump that heats water for hot water supply, and a heat pump drive unit that operates the heat pump by inputting external AC power, A water heater in which grid power supplied from a grid and output power of an inverter connected to a storage battery are switched and input as the external AC power, a voltage detection unit that detects the voltage of the external AC power; a determination unit that determines whether the external AC power is the grid power or the output power of the inverter based on the voltage continuously detected by the voltage detection unit, the heat pump drive unit When the determining unit determines that the external AC power is the grid power, the heat pump is operated in a normal mode, and when the external AC power is determined to be the output power of the inverter, the The heat pump is configured to operate in a limited mode that consumes less power than the normal mode.

According to this configuration, the above-mentioned voltage detection section and determination section are provided, and when the determination section determines that the external AC power is the output power of the inverter, the heat pump drive section operates the heat pump with lower power consumption than in the normal mode. Since it is configured to operate in a limited mode, it is possible to reduce power consumption when the storage battery power is being used without having to obtain information about its usage from the outside. .

The determination unit calculates a degree of distortion of the voltage detected by the voltage detection unit, and determines whether the external AC power is the grid power or the output power of the inverter based on this degree of distortion. It may be configured as follows.

The heat pump driving section has a determination mode in which the heat pump is operated at a higher power consumption than the limit mode within a predetermined time after the start of input of the external AC power, and the determination section operates within a period of the determination mode. The determination may be made at any time.

The determination unit determines whether the external AC power is the output power of the inverter, depending on whether the voltage detected by the voltage detection unit includes a voltage component of a carrier frequency of the inverter that is PWM controlled. It may be configured to determine whether it is grid power.

The water heater may further include a combustion type water heater.

The present invention has the configuration described above, and when the power of the storage battery is being used, it is possible to perform a power consumption suppressing operation without acquiring information on the fact that the power is being used from the outside. This has the effect of being able to provide a hot water supply device that can.

FIG. 1 is a diagram showing a schematic configuration of a water heater that is an example of this embodiment. FIG. 2 is a diagram showing an example of the input voltage and input current of external AC power input to the water heater when grid power is selected by the output switching device of the storage battery unit. FIG. 3 is a diagram showing an example of the input voltage and input current of external AC power input to the water heater when the output power of the inverter is selected by the output switching device of the storage battery unit. The waveform diagram in the upper part of FIG. 4(A) is a diagram showing an example of the voltage waveform output from the high-pass filter of the determination unit when the external AC power is grid power, and the waveform diagram in the lower part of FIG. 4(A) The figure is a diagram showing an example of the voltage waveform output from the high-pass filter of the determination unit when the external AC power is the output power of the inverter. The upper and lower waveform diagrams in FIG. FIG. 4A is an enlarged view of a certain period of the upper and lower waveform diagrams in the horizontal axis direction.

Hereinafter, preferred embodiments will be described with reference to the drawings. Note that the present invention is not limited to the following embodiments.

(Embodiment)
FIG. 1 is a diagram showing a schematic configuration of a water heater that is an example of this embodiment. This water heater 1 is a hybrid water heater that includes a heat pump unit 2 and a hot water storage unit 3A, and has a combustion water heater 4 built into the hot water storage unit 3A. External alternating current power AC is supplied to the water heater 1 from an external storage battery unit 9.

The storage battery unit 9 includes a storage battery 91, an inverter 92, and an output switching device 93. The output switching device 93 detects a voltage input from a stable power system 8 such as a commercial power system, and during normal times when the voltage input from the power system 8 is detected, the power of the power system 8 is switched to external AC power. Output as AC. On the other hand, during a power outage when the voltage input from the power grid 8 is not detected, the inverter 92 is operated under PWM (pulse width modulation) control to convert the DC power from the storage battery 91 to AC power at the same frequency as the power grid 8. and outputs it to the water heater 1 as external alternating current power AC. In this way, the storage battery unit 9 is configured to output power from the power grid 8 (grid power) to the water heater 1 during normal times, and output power output from the inverter 92 to the water heater 1 during a power outage. Note that the output switching device 93 of the storage battery unit 9 operates so that when switching the output external AC power AC between the grid power and the output power of the inverter 92, there is a period in which neither power is output (connected). It is composed of

The hot water storage unit 3A includes a hot water storage tank 3 for storing hot water, a combustion water heater 4 such as an instantaneous gas water heater, a control device 5, and the like.

The hot water storage tank 3 is connected to a water inlet passage through which clean water is supplied to its lower part, and a hot water supply passage through which hot water is supplied to its upper part. Further, a passage is provided between the hot water supply passage and the combustion type water heater 4 so that the hot water in the hot water supply passage can be appropriately heated by the combustion type water heater 4. Further, a passage for supplying hot water from the hot water storage tank 3 to the condensing heat exchanger 27 of the heat pump 21 is connected to the lower part of the hot water storage tank 3, and a passage that supplies hot water heated by the condensing heat exchanger 27 to the upper part of the hot water storage tank 3 is connected. A supply passage is provided. Note that the hot water passages provided in the hot water storage unit 3A are appropriately provided with electromagnetic valves, pumps, various sensors, etc., but a well-known configuration can be used for these configurations, including each passage, etc. is omitted. Further, the hot water supply passage may be configured not only to be connected to an external hot water tap but also to a bathtub so that it can be filled with hot water. Further, a heat exchanger or the like for reheating the bath may be provided to enable reheating of the bath. Further, a heating heat exchanger or the like may be provided and connected to a heating terminal (for example, a bathroom dryer, a hot water mat for floor heating, etc.).

In this hot water supply device 1, low-temperature hot water is supplied to the heat pump 21 from the lower part of the hot water storage tank 3, and the hot water heated by the heat pump 21 is sent to the upper part of the hot water storage tank 3 and stored therein. Furthermore, when an external hot water supply tap or the like is opened, the hot water discharged from the upper part of the hot water storage tank 3 and the incoming clean water are mixed and hot water is supplied so that the hot water supply temperature becomes the set temperature. Furthermore, when the amount of heat stored in the hot water storage tank 3 is insufficient, such as when hot water is being supplied to a high temperature, the combustion type water heater 4 is configured to supplementally heat the hot water before supplying the hot water. In this way, the combustion type water heater 4 is used auxiliary, and it is also possible to have a configuration in which the combustion type water heater 4 is not provided.

The control device 5 includes a power supply section and a control section operated by power supplied from the power supply section. The control unit includes a CPU, a memory, and the like, and is configured with, for example, a microcontroller. The control unit inputs operation signals from a remote controller (not shown), etc., and signals from various sensors (not shown) such as a temperature sensor, and the CPU executes a control program stored in the memory. The entire water heater 1 is controlled. External alternating current power AC is input to the power supply section from the storage battery unit 9. The power supply unit converts external AC power AC into power used in each internal part of the hot water storage unit 3A (control unit of the control device 5, internal equipment of the combustion water heater 4, pump not shown, etc.), and supplies the converted power to each part. do.

The heat pump unit 2 includes a heat pump 21, a heat pump drive section 22, a heat pump control section 23, a voltage detection section 24, and a determination section 25. The heat pump control section 23 and the determination section 25 may be composed of a microcontroller or the like, or a part thereof may be composed of an electric circuit or the like.

The heat pump 21 has a well-known configuration including a compressor 26, a condensing heat exchanger 27, an expansion valve 28, and an evaporative heat exchanger 29, which are connected by refrigerant piping. In this heat pump 21, the refrigerant sealed in the refrigerant pipe is compressed and heated by the compressor 26, and the hot water flowing between it and the hot water storage tank 3 is heated by heat exchange with the high-temperature refrigerant in the condensing heat exchanger 27. do. After this heat exchange, the refrigerant expands in the expansion valve 28 to become lower temperature than the outside air, absorbs heat from the outside air in the evaporative heat exchanger 29, and is then introduced into the compressor 26 again. The evaporative heat exchanger 29 includes a blower 29a.

The heat pump control unit 23 is communicably connected to the control device 5, and controls the heat pump drive unit 22 based on operation on/off commands and the like from the control device 5.

External alternating current power AC is input to the heat pump drive unit 22 from the storage battery unit 9 . The heat pump drive unit 22 converts external alternating current power AC into electric power used by each of the compressor 26, expansion valve 28, and blower 29a in order to control the heat pump 21 based on commands from the heat pump control unit 23. Supply to each. In this way, the heat pump drive section 22 includes a power conversion section, and this power conversion section includes a capacitor input type rectifier circuit. The commands from the heat pump control unit 23 that are input to the heat pump drive unit 22 include commands that specify an operation mode (normal mode, limited mode, etc.), which will be described later.

The voltage detection section 24 detects the voltage of the external alternating current power AC input from the storage battery unit 9 and outputs it to the determination section 25 . Then, the determination unit 25 determines whether the external AC power AC is grid power (power from the power grid 8) or the output power of the inverter 92, based on the voltage continuously detected by the voltage detection unit 24. A determination is made and the determination result is output to the heat pump control unit 23.

The heat pump control unit 23 outputs a command to the heat pump drive unit 22 to operate the heat pump 21 in the normal mode if the determination result of the determination unit 25 is that the external AC power AC is grid power. On the other hand, if the determination result of the determination unit 25 is that the external AC power AC is the output power of the inverter 92, a command is output to the heat pump drive unit 22 to operate the heat pump 21 in the limited mode. The heat pump drive unit 22 operates the heat pump 21 according to the mode instructed by the heat pump control unit 23. The limited mode is a mode in which power consumption (output) is smaller than in the normal mode, and specifically, the heat pump drive unit 22 operates, for example, the compressor 26 so that the power consumption is smaller than in the normal mode. That is, in the limited mode, the rotational speed (rotational speed) of the motor of the compressor 26 is made lower than in the normal mode. Furthermore, the blower 29a may be operated with lower power consumption than in the normal mode.

Next, a specific example of the configuration of the determination unit 25 will be described.

[First configuration example]
First, a first configuration example will be explained. FIG. 2 is a diagram showing an example of the input voltage V1 and input current I1 of the external AC power AC input to the water heater 1 when grid power is selected by the output switching device 93 of the storage battery unit 9. On the other hand, FIG. 3 is a diagram showing an example of the input voltage V2 and input current I2 of the external AC power AC input to the water heater 1 when the output power of the inverter 92 is selected by the output switching device 93.

As shown in FIG. 2, when grid power is selected, a high quality (low distortion) input voltage V1 is input to the water heater 1. On the other hand, as shown in FIG. 3, when the output power of the inverter 92 is selected, the distortion of the input voltage V2 increases. This is because the heat pump drive unit 22 has a built-in capacitor input type rectifier circuit, so distortion increases when the intermittently flowing current I2 increases.

Therefore, in the case of the first configuration example, the determination unit 25 calculates the degree of distortion of the voltage of the external AC power AC, and based on this degree of distortion, determines whether the external AC power AC is the grid power or the output power of the inverter 92. I'm trying to determine if there is.

For example, the determination unit 25 derives the voltage waveform of the external AC power AC and the effective value or average value of the voltage of the external AC power AC based on the voltage of the external AC power AC detected by the voltage detection unit 24. , the degree of distortion of the voltage of the external AC power AC is calculated based on the voltage waveform of the external AC power AC.

An example of a method for calculating the degree of distortion is to generate a sine wave waveform whose effective value and cycle are synchronized with the voltage of the detected external AC power AC, and to accurately match the phase by PLL control or the like. Next, the area A of a predetermined period (for example, one period) of the sine wave waveform is determined by sampling the generated sine wave waveform and integrating the absolute values of the sampled values. Next, the voltage waveform of external AC power AC is similarly sampled, and the absolute value of the difference between the sample value of this external voltage waveform and the sample value of the above-mentioned sine wave waveform is integrated for a predetermined period, and the sine wave waveform is Find the integrated value B of the difference between the external voltage waveform and the external voltage waveform. Then, the distortion degree (total harmonic distortion THD) of the voltage of the external alternating current power AC is determined by (integrated value B of the difference ÷ area A of the sine wave waveform x 100). Note that in order to prevent false detection, the area A of the sine wave waveform and the integrated value B of the differences may be determined as a moving average of the most recent cycles (for example, 4 cycles).

Further, the determination unit 25 determines whether the degree of distortion obtained as described above exceeds a predetermined threshold value, and if it exceeds a predetermined threshold, determines that the external AC power AC is the output power of the inverter 92, and If there is no external AC power, it is determined that the external AC power is grid power.

Note that the heat pump control unit 23 and the control unit of the control device 5 are restarted when the power supply is restarted after the power supply is stopped. That is, when the external AC power AC is switched between the grid power and the output power of the inverter 92 by the output switching device 93 of the storage battery unit 9, the external AC power AC is temporarily not supplied, and the external AC power AC is Each time the switching is performed, the heat pump control section 23 and the control section of the control device 5 are restarted.

Furthermore, when the external AC power AC is the output power of the inverter 92, the distortion of the voltage waveform of the external AC power AC increases as the power consumption increases. Doing so will enable more accurate judgment.

Therefore, the first configuration example may be configured as follows. In addition to the above-mentioned normal mode and restriction mode, the heat pump 21 has a determination mode as an operation mode. Then, the heat pump control unit 23 outputs a determination mode command to the heat pump drive unit 22 every time input of external AC power AC is started (every time it is started). The heat pump drive unit 22 operates the heat pump 21 at a higher power consumption (output) than in the limit mode within a predetermined time after inputting the determination mode command (that is, within a predetermined time after input of external AC power AC starts). (operation in judgment mode). Then, the determination unit 25 performs the above-described determination within the period of the determination mode (within the above-mentioned predetermined time). In the determination mode, in order to operate the heat pump 21 with higher power consumption than in the limit mode, for example, the compressor 26 may be operated at the maximum output or a predetermined output close to the maximum output.

[Second configuration example]
Next, a second configuration example will be explained. As is well known, the inverter 92 is configured using a plurality of switching elements, and when these switching elements are turned on and off by PWM control, the DC power of the storage battery 91 is converted into AC power and output. The frequency of the AC power output from this inverter 92 (that is, the output frequency of the inverter 92) is configured to be the same as the frequency of the power grid 8, but the output voltage of the inverter 92 is The voltage component of the carrier frequency used is superimposed.

Therefore, in the case of the second configuration example, the determination unit 25 determines whether the external AC power AC is the output power of the inverter 92 or the system power I am trying to determine whether it is.

In this case, the determination unit 25 inputs the voltage of the external AC power detected by the voltage detection unit 24, attenuates the voltage component of the frequency of the grid power, and passes the voltage component of the carrier frequency of the inverter 92. It has a filter for output. As this filter, for example, a high-pass filter whose cutoff frequency is higher than the frequency of the grid power and lower than the carrier frequency can be used. For example, when the frequency of grid power is 60 Hz and the carrier frequency is 16 to 17 kHz, a high-pass filter with a cutoff frequency of 1 kHz, for example, can be used.

The waveform diagram in the upper part of FIG. 4(A) shows the output from the high-pass filter when the external AC power AC is input to the high-pass filter of the determination unit 25 via the voltage detection unit 24 when the external AC power AC is grid power. FIG. 3 is a diagram showing an example of an output voltage (V1f) waveform. Further, the waveform diagram in the lower part of FIG. 4A shows the case where the external AC power AC is the output power of the inverter 92 and when the external AC power AC is input to the high-pass filter of the determination unit 25 via the voltage detection unit 24. It is a figure which shows an example of the voltage (V2f) waveform output from the same high pass filter. Moreover, the waveform diagrams in the upper and lower stages of FIG. 4(B) are diagrams in which a portion of the period C1 in the waveform diagrams in the upper and lower stages of FIG. 4(A) is expanded in the horizontal axis direction. Note that in the upper and lower waveform diagrams of FIGS. 4A and 4B, the voltage on the vertical axis and the time on the horizontal axis are shown in arbitrary units, respectively. As shown in the lower waveform diagram of FIG. 4B, the period Tc of the voltage V2f is a period corresponding to the carrier frequency of the PWM control of the inverter 92.

As can be seen by comparing the upper and lower waveform diagrams in Figures 4 (A) and (B), when the voltage component of the frequency of the grid power (grid voltage) is attenuated by a high-pass filter, the external AC power AC becomes the grid power. It is possible to distinguish between the case of the output power of the inverter 92 and the case of the output power of the inverter 92.

Therefore, in the determination unit 25, a predetermined value Vt as shown in FIG. When this occurs, it is determined that the external AC power AC is the output power of the inverter 92, and other than this, it is determined that the external AC power is the grid power.

Note that in the above, a high-pass filter is used as an example of the filter in the determination unit 25, but a band-pass filter may be used instead. By using a filter in this way, the voltage component of the carrier frequency of the inverter 92 can be easily extracted, but the present invention is not limited to this, and any configuration that can extract the voltage component of the carrier frequency of the inverter 92 may be used.

Furthermore, as described above, the heat pump control unit 23 and the like are restarted each time the input external AC power AC is switched by the output switching device 93, so in the second configuration example as well, the input of the external AC power AC is The determining unit 25 may perform the above-mentioned determination within a predetermined period of time after the start of input (every time it is started). In this second configuration example, it is assumed that the initial mode before the determination by the determination unit 25 is set to either the normal mode or the restricted mode.

In this embodiment, as described above, the voltage detection section 24 that detects the voltage of the external AC power AC and the determination section 25 as in the first and second configuration examples are provided. When it is determined that the output power is the output power of , it is possible to reduce power consumption without obtaining information about its use from outside. This makes it possible to lengthen the usage time of the storage battery 91 during a power outage.

From the above description, many modifications and other embodiments of the invention will be apparent to those skilled in the art. Accordingly, the above description is to be construed as illustrative only, and is provided for the purpose of teaching those skilled in the art the best mode of carrying out the invention. Substantial changes may be made in the structural and/or functional details thereof without departing from the spirit of the invention.

INDUSTRIAL APPLICATION This invention is useful as a water heater etc. which can operate with reduced power consumption even when the power of a storage battery is being used, without acquiring information about the fact that the power is being used from the outside.

1 Water heater 2 Heat pump unit 21 Heat pump 22 Heat pump drive section 23 Heat pump control section 24 Voltage detection section 25 Judgment section 4 Combustion water heater 8 Power system 9 Storage battery unit 91 Storage battery 92 Inverter 93 Output switching device

Claims (2)

It is equipped with a heat pump that heats water for hot water supply, and a heat pump drive unit that operates the heat pump by inputting external AC power, so that the system power supplied from the power grid and the output power of an inverter connected to a storage battery are connected to each other. A water heater that is switched and inputted as the external AC power,
a voltage detection unit that detects the voltage of the external AC power;
A determination unit that calculates a degree of distortion of the voltage continuously detected by the voltage detection unit and determines whether the external AC power is the grid power or the output power of the inverter based on this degree of distortion. and,
Equipped with
The heat pump drive unit includes:
When the determination unit determines that the external AC power is the grid power, the heat pump is operated in a normal mode, and when the determination unit determines that the external AC power is the output power of the inverter, the heat pump is operated. configured to operate in a limited mode with lower power consumption than the normal mode ,
having a determination mode in which the heat pump drive unit operates the heat pump at a higher power consumption than the limit mode within a predetermined time after the input of the external AC power is started;
The determination unit includes:
configured to perform the determination within the period of the determination mode;
Water heater. The water heater according to claim 1 , further comprising a combustion type water heater.

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