JP7654337B2 - Air conditioning equipment - Google Patents

Description

This disclosure relates to an air conditioner that uses a refrigerator with an electric compressor.

For example, in the air conditioning system described in Patent Document 1, the temperature difference between the first air conditioner and the second air conditioner is compared to determine the control for starting up the two air conditioners.

Patent No. 6578920

For example, an air conditioning unit that cools a so-called server room in which information and communication technology equipment (hereinafter referred to as ICT equipment) is installed is equipped with a heat exchanger that cools the air drawn in from the server room and supplies it to the server room, and maintains the temperature inside the server room within a specified temperature range by adjusting the refrigeration capacity generated by the heat exchanger.

The refrigeration capacity is adjusted by controlling the compressor's rotation speed, i.e., the frequency of the drive current when driving the electric compressor. The compressor's drive control unit then controls the drive frequency so that the air temperature before heat exchange in the heat exchanger or the air temperature after heat exchange in the heat exchanger (hereinafter, these temperatures are referred to as air conditioner side temperatures) becomes a preset temperature.

This disclosure discloses an example of compressor startup control during a power outage, focusing on temperature changes during a power outage in the space to be air-conditioned, in an air conditioning device in which the drive frequency is controlled so that the air conditioner side temperature becomes a preset temperature.

It is desirable for an air conditioner that uses a refrigerator (1) having an electric compressor (2) to have at least one of the following components:

That is, the components are a heat exchanger (5) that cools or heats the air drawn from the space to be air-conditioned and supplies it to the space to be air-conditioned, a room temperature sensor (S1) that detects the air temperature in the space to be air-conditioned, the room temperature sensor (S1) being powered by an uninterruptible power supply at least during a power outage, an air conditioning temperature sensor (S2) that detects the air temperature before heat exchange in the heat exchanger (5) or the air temperature after heat exchange in the heat exchanger (5) (hereinafter, these temperatures are referred to as air conditioner side temperatures), and a drive current frequency (hereinafter, referred to as drive frequency) that drives the compressor (2). The dynamic control unit (6A) includes a drive control unit (6A) capable of controlling the drive frequency at least by power failure start control or normal control, and a temperature estimation unit (6B) that estimates the air conditioner side temperature from the temperature detected by the room temperature sensor (S1) using the difference between the temperature detected by the room temperature sensor (S1) and the temperature detected by the air conditioning temperature sensor (S2) when the compressor (2) is operating under normal control, and the drive control unit (6A) determines at least the acceleration of the drive frequency using the temperature difference (ΔT) and the power failure time (Ts), and the power failure start control is a control that increases and changes the drive frequency at the determined acceleration.

The power failure startup control is executed when the power supply is restored after it has been stopped, and the normal control is executed after the power failure startup control is completed, and adjusts the drive frequency so that the temperature detected by the air conditioning temperature sensor (S2) becomes a preset temperature.

The temperature estimated by the temperature estimation unit (6B) as the air conditioner side temperature when the power supply is restored is defined as the estimated air conditioner side temperature, the temperature detected by the air conditioner temperature sensor (S2) when the power supply is stopped is defined as the air conditioner side temperature when stopped, the difference between the estimated air conditioner side temperature and the air conditioner side temperature when stopped is defined as the temperature difference (ΔT), and the time from when the power supply is stopped until the power supply is restored is defined as the power outage time (Ts).

As a result, with this air conditioning device, the compressor (2) can be started quickly after power is restored. As a result, even if a power outage occurs, the air temperature in the space to be air-conditioned can be prevented from changing significantly.

Incidentally, the symbols in parentheses above are examples showing the corresponding relationship with the specific configurations etc. described in the embodiments described below, and the present disclosure is not limited to the specific configurations etc. shown by the symbols in parentheses above.

1 is a diagram showing an air conditioning device according to a first embodiment; 4 is a table showing a start-up pattern of start-up control during a power outage according to the first embodiment; 13 is a graph showing changes in temperature in a server room.

The following "embodiment of the invention" shows an example of an embodiment that falls within the technical scope of this disclosure. In other words, the invention-specific matters described in the claims are not limited to the specific configurations and structures shown in the embodiment below.

At least one of each of the components or parts described with a reference number is provided, unless otherwise specified by "one". In other words, unless otherwise specified by "one", two or more of the components may be provided. The air conditioner shown in this disclosure includes at least the components or parts described with a reference number, as well as the structural parts shown in the drawings.

First Embodiment
1. Configuration of Air Conditioner
In this embodiment, the present disclosure is applied to an air conditioner that conditions air in a communication equipment room, a server room, etc. (hereinafter, referred to as a server room.) In other words, the air conditioner according to this embodiment treats the server room as a space to be air-conditioned and adjusts the temperature, etc., of the space to be air-conditioned.

At least one piece of information and communication technology equipment (hereinafter referred to as ICT equipment) is installed in the server room. The ICT equipment is supplied with power via an uninterruptible power supply (hereinafter referred to as UPS).

The refrigerator 1 shown in FIG. 1 generates cold heat for air conditioning the server room. The refrigerator 1 is configured as a vapor compression refrigerator having an electric compressor 2. Specifically, the refrigerator 1 has the compressor 2, a radiator 3, a pressure reducer 4, an evaporator 5, a control device 6, a room temperature sensor S1, an intake temperature sensor S2, and an exhaust temperature sensor S3.

The compressor 2 compresses the low-pressure gas-phase refrigerant that flows out from the evaporator 5. The radiator 3 cools the high-pressure refrigerant that is discharged from the compressor 2 and has an increased temperature. In the radiator 3 according to this embodiment, the cooled refrigerant is condensed (liquefied).

The pressure reducer 4 reduces the pressure of the refrigerant flowing out from the radiator 3. The pressure reducer 4 in this embodiment is composed of a thermostatic expansion valve. The thermostatic expansion valve automatically adjusts the opening (pressure reduction) so that the degree of superheat of the refrigerant at the outlet side of the evaporator 5 becomes a predetermined value.

The evaporator 5 evaporates the liquid-phase refrigerant decompressed by the pressure reducer 4 to generate refrigeration capacity, i.e., cold heat. Specifically, the evaporator 5 exchanges heat between the refrigerant and the air conditioning air supplied to the server room, cooling the air conditioning air.

The air conditioning system includes a refrigeration unit 1 and a blower 5A. The blower 5A draws in air from within the server room and blows the air to the evaporator 5, and supplies the air cooled by the evaporator 5 to the server room.

The control device 6 controls the components of the air conditioner, such as the compressor 2 and the blower 5A. The detection values of the room temperature sensor S1, the intake temperature sensor S2, and the exhaust temperature sensor S3 are input to the control device 6.

The room temperature sensor S1 detects the air temperature inside the server room (hereinafter referred to as server room temperature T1). In this embodiment, the room temperature sensor S1 detects the air temperature before it is heated by the heating element placed inside the server room, that is, the air temperature before it is heated by the ICT equipment.

Specifically, the server room in this embodiment is separated into a cold aisle (a space for supplying cold air) and a hot aisle (a space for exhausting hot air). The room temperature sensor S1 detects the air temperature in the cold aisle.

The cold aisle is a space for distributing and supplying the cold air supplied from the evaporator 5 to each piece of ICT equipment. The hot aisle is a space where the air whose temperature has increased after cooling each piece of ICT equipment gathers. The blower 5A then draws in the air in the hot aisle and supplies it to the evaporator 5.

The intake temperature sensor S2 detects the air temperature before heat exchange in the evaporator 5 (hereafter referred to as intake temperature T2). The outlet temperature sensor S3 detects the air temperature after heat exchange in the evaporator 5 (hereafter referred to as outlet temperature T3).

The room temperature sensor S1 is supplied with power via a UPS. The intake temperature sensor S2 and the exhaust temperature sensor S3 are supplied with power from the air conditioning system's power supply (not shown). Therefore, in the event of a power outage, the intake temperature sensor S2 and the exhaust temperature sensor S3 stop functioning.

Incidentally, the air conditioner according to this embodiment is equipped with an engine-driven power supply (not shown) as a power supply for use during a power outage (emergency use). When the power supply from the commercial power source is cut off, the engine automatically starts and power is supplied to the air conditioner.

2. Control operation of the control device
The control device 6 has at least a drive control unit 6A and a temperature estimation unit 6B. The control device 6 according to this embodiment is configured with a microcomputer having a CPU, a ROM, a RAM, etc. The drive control unit 6A and the temperature estimation unit 6B are realized by the CPU executing software that is pre-stored in a non-volatile storage unit (not shown) such as a ROM.

<2.1 Drive control unit>
The drive control unit 6A controls the operation of the compressor 2 via an inverter type drive circuit (not shown). Specifically, the drive control unit 6A controls the frequency of a drive current (hereinafter referred to as a drive frequency). The drive current is a current that drives the compressor 2.

The drive control unit 6A (hereinafter referred to as the control device 6) can control the drive frequency at least by power failure startup control or normal control. Power failure startup control is a control that is executed when the power supply to the air conditioner is restored after the power supply has been stopped. Details of the power failure startup control will be described later.

Normal control is executed after the power failure startup control ends and when power is normally supplied, and adjusts the drive frequency so that the temperature detected by the suction temperature sensor S2, i.e., the suction temperature T2, becomes a preset temperature (hereinafter referred to as the set temperature).

Specifically, when the suction temperature T2 is higher than the set temperature, the control device 6 increases the drive frequency. When the suction temperature T2 is lower than the set temperature, the control device 6 decreases the drive frequency. This maintains the suction temperature T2 at the set temperature.

The control device 6 according to this embodiment controls the airflow rate of the blower 5A so that the "temperature difference between the blowing temperature T3 and the set temperature" or the "temperature difference between the blowing temperature T3 and the suction temperature T2" becomes a predetermined temperature difference. In other words, the control device 6 controls the blower 5A so that the blowing temperature T3 becomes a predetermined temperature.

<2.2 Temperature estimation section>
The temperature estimation unit 6B uses the detected temperature (server room temperature T1) of the room temperature sensor S1 to estimate the air temperature before heat exchange in the evaporator 5. That is, the temperature estimation unit 6B estimates the temperature by using the difference between the server room temperature T1 and the suction temperature T2 when the compressor 2 is operating under normal control.

Specifically, the temperature estimation unit 6B stores the difference between the server room temperature T1 and the intake temperature T2 during normal control, and acquires the relational equation between the server room temperature T1 and the intake temperature T2 or the value of the difference by machine learning or the like. Then, the temperature estimation unit 6B estimates the air temperature using the acquired relational equation or the value of the difference.

<2.3 Start-up control during power outage>
<Outline of startup control during power outage>
The power failure startup control is a control that uses the temperature difference ΔT and the power failure time Ts to determine the acceleration of the drive frequency and the upper limit drive frequency fmax, and increases the drive frequency to the upper limit drive frequency fmax at the determined acceleration.

The temperature difference ΔT refers to the difference between the estimated suction temperature T4 and the air conditioner side temperature T5 when the air conditioner is stopped. The estimated suction temperature T4 refers to the temperature estimated by the temperature estimation unit 6B as the suction temperature when the power supply is restored after a power outage.

The air conditioner-side temperature T5 at the time of shutdown refers to the temperature detected by the intake temperature sensor S2 when the power supply is stopped. In this embodiment, it is the latest intake temperature T2 among the intake temperatures T2 stored for the above machine learning.

The power outage time Ts is the time from when the power supply is stopped until when the power supply is restored. The upper limit drive frequency fmax is the drive frequency that ends the power outage startup control. In other words, when the drive frequency reaches the upper limit drive frequency fmax, the control device 6 transitions the control of the compressor 2 to normal control.

<Details of startup control during power outage>
In the power outage startup control of this embodiment, the control device 6 determines the startup control to be executed from among three startup control patterns based on the temperature difference ΔT and the power outage duration Ts, and then executes the determined startup control (see Figure 2).

<First startup control pattern>
The first startup control pattern is a startup control that is executed when the temperature difference ΔT is less than a predetermined value (e.g., 5 deg) and greater than 0 deg, and when the power outage time Ts is greater than or equal to a predetermined time (e.g., 5 min).

Hereinafter, the acceleration of the drive frequency in the first startup control pattern is referred to as the reference acceleration, and the upper limit drive frequency fmax in the first startup control pattern is referred to as the reference upper limit frequency. Note that the reference acceleration and the reference upper limit frequency are stored in advance in a ROM or the like.

<Second startup control pattern>
The second startup control pattern is a startup control that is executed when the temperature difference ΔT is equal to or greater than the above-mentioned predetermined value, and is a startup control that increases the drive frequency at an acceleration greater than the reference acceleration.

In other words, when the temperature difference ΔT is 5 deg or more, the control device 6 increases the drive frequency at the above acceleration regardless of the length of the power outage time Ts (see FIG. 2). Note that the upper limit drive frequency fmax for the second startup control pattern is the same as the reference upper limit frequency.

<Third startup control pattern>
The third startup control pattern is a startup control that is executed when the temperature difference is less than the above-mentioned predetermined value and is greater than 0 deg, and the power outage time Ts is less than the above-mentioned predetermined time. Then, the control device 6 increases the drive frequency to the reference upper limit frequency at an acceleration smaller than the reference acceleration.

3. Features of the Air Conditioner According to the Present Embodiment (Especially, Start-up Control During Power Outage)
It is rare for the air temperature in the server room to be the same throughout (uniform temperature). However, the air drawn into the blower 5A is sufficiently mixed (stirred) before it reaches the evaporator 5, so that the temperature of the air that reaches the evaporator 5 is almost uniform.

In other words, the air that is sucked in from the server room and reaches the evaporator 5 has a temperature that appropriately represents the air temperature in the server room (hereinafter referred to as the appropriate temperature). Therefore, in normal control, the drive frequency is controlled so that the suction temperature T2 becomes the set temperature.

When a power outage occurs, the blower 5A stops, but the ICT equipment continues to operate even during the power outage by receiving power from the UPS. As a result, the difference between the ambient temperature of the intake temperature sensor S2 and the server room temperature T1 increases as the power outage continues.

Therefore, when the power supply is restored, that is, immediately after the power is restored, the temperature detected by the intake temperature sensor S2 (intake temperature T2) is lower than the temperature of the server room temperature T1. Moreover, the longer the power outage time Ts, the greater the difference between the server room temperature T1 immediately after the power is restored and the intake temperature T2.

Therefore, if the acceleration of the drive frequency and the upper limit drive frequency fmax are determined using the suction temperature T2 immediately after re-energization, there is a high possibility that the cooling capacity will be insufficient and that the operation of compressor 2 cannot be appropriately controlled.

In response to this, it is possible to determine the acceleration of the drive frequency and the upper limit drive frequency fmax using the suction temperature T2 when the time required for the suction temperature T2 to reach the optimum temperature after the blower 5A starts operating (hereinafter referred to as the optimum time) has elapsed.

However, with this method, the compressor 2 cannot be started until the appropriate time has elapsed after power is restored, which causes the air temperature in the server room to rise further. Incidentally, the appropriate time is generally about several minutes.

In contrast, in this embodiment, the ambient temperature (estimated intake temperature T4) of the intake temperature sensor S2 is estimated using the server room temperature T1, and the estimated intake temperature T4 is used to determine the startup control pattern to be executed for startup control during a power outage.

Therefore, in this embodiment, after power is restored, the compressor 2 can be started before the appropriate time has elapsed. As a result, even if a power outage occurs, the air temperature in the server room is prevented from rising significantly (see FIG. 3).

In this embodiment, when a power outage occurs in the commercial power supply, power is supplied from the engine-driven emergency power supply device to the air conditioner, and power is duplicated. The engine-driven emergency power supply device takes longer to duplicate power than an emergency power supply that uses a storage battery, such as a UPS.

Furthermore, the emergency power supply can supply less power than a commercial power supply. For this reason, if the compressor 2 is started under the same conditions (e.g., the second start-up control pattern) regardless of the temperature difference ΔT and the power outage duration Ts, there is a possibility that the emergency power supply will be overloaded.

However, in this embodiment, the compressor 2 is started by selecting a startup control pattern according to the temperature difference ΔT and the power outage duration Ts, which reduces pressure on the emergency power supply device and prevents the air temperature in the server room from rising significantly.

Other Embodiments
In the above embodiment, the server room is divided into a cold aisle (a space for supplying cold air) and a hot aisle (a space for exhausting hot air), and the room temperature sensor S1 detects the air temperature in the cold aisle. However, the present disclosure is not limited to this.

That is, the disclosure may be, for example, a configuration in which the room temperature sensor S1 detects the air temperature in a hot aisle, or a configuration in which the server room is not separated into a cold aisle and a hot aisle.

In the third startup control pattern according to the embodiment described above, the control device 6 increases the drive frequency to the reference upper limit frequency at an acceleration smaller than the reference acceleration. However, the present disclosure is not limited to this.

That is, in the disclosure, for example, in the third startup control pattern, the control device 6 may increase the drive frequency at the reference acceleration up to an upper limit drive frequency fmax that is lower than the reference upper limit frequency.

In the above-described embodiment, when the temperature difference ΔT is equal to or greater than a predetermined value, the increase acceleration of the drive frequency is the same regardless of the power outage time Ts. However, the present disclosure is not limited to this. In other words, the present disclosure may be configured such that, for example, even when the temperature difference ΔT is equal to or greater than a predetermined value, the increase acceleration differs depending on the power outage time Ts.

The temperature estimation unit 6B according to the embodiment described above stores the difference between the server room temperature T1 and the intake temperature T2 during normal control, and obtains the relational equation between the server room temperature T1 and the intake temperature T2 or the value of the difference through machine learning or the like.

However, the present disclosure is not limited to this. In other words, the disclosure may be configured, for example, to store a relational equation or a value in advance as a relational equation between the server room temperature T1 and the suction temperature T2 or a value of the difference between them, and to estimate the suction temperature using the relational equation or value.

In the above embodiment, the compressor 2 is controlled so that the suction temperature T2 becomes the set temperature. However, the present disclosure is not limited to this. That is, the present disclosure may be configured, for example, so that the compressor 2 is controlled so that the blowing temperature T3 becomes the set temperature.

The temperature estimation unit 6B in this configuration estimates the air temperature after heat exchange in the evaporator 5, i.e., the blowing temperature, using the server room temperature T1. The airflow rate of the blower 5A in this configuration may be determined as a function value of the drive frequency.

The air conditioner according to the embodiment described above is configured to directly cool the air supplied to the room using the evaporator 5. However, the present disclosure is not limited to this. That is, the present disclosure may be configured to indirectly cool the air supplied to the room, for example, by supplying cold water cooled by the evaporator 5 to an indoor heat exchanger such as an air handling unit.

The air conditioner according to the above embodiment is an air conditioner that cools the space to be air-conditioned. However, the present disclosure is not limited to this. In other words, the present disclosure is also applicable to, for example, heating that utilizes heat generated by the condenser 3.

The startup control during a power outage according to the embodiment described above uses the temperature difference ΔT and the power outage duration Ts to determine the startup control from among three startup control patterns. However, the present disclosure is not limited to this. In other words, the present disclosure may be configured to, for example, determine at least the acceleration of the drive frequency using the temperature difference ΔT and the power outage duration Ts, and to control the startup control to increase and change the drive frequency at the determined acceleration.

The air conditioner according to the above embodiment is equipped with an engine-driven power supply as an emergency power supply. However, the present disclosure is not limited to this. That is, the present disclosure may be, for example, a configuration that does not include an emergency power supply, or a configuration that includes an emergency power supply configured with a storage battery.

Furthermore, the present disclosure is not limited to the above-mentioned embodiments as long as it conforms to the spirit of the disclosure described in the above-mentioned embodiments. Therefore, the present disclosure may be a configuration in which at least two of the above-mentioned embodiments are combined, or a configuration in which any of the constituent elements illustrated or the constituent elements described with reference numerals in the above-mentioned embodiments are eliminated.

REFERENCE SIGNS LIST 1 Refrigerating machine 2 Compressor 3 Radiator 4 Pressure reducer 5 Evaporator 5A Fan 6 Control device S1 Room temperature sensor S2 Intake temperature sensor S3 Outlet temperature sensor

Claims (3)

In an air conditioner using a refrigerator having an electric compressor,
a heat exchanger that cools or heats air drawn from a space to be air-conditioned and supplies the air to the space to be air-conditioned;
a room temperature sensor that detects an air temperature in a space to be air-conditioned and that is supplied with power from an uninterruptible power supply at least during a power outage;
an air conditioner temperature sensor that detects the air temperature before heat exchange in the heat exchanger or the air temperature after heat exchange in the heat exchanger (hereinafter, these temperatures are referred to as air conditioner side temperatures);
A drive control unit that controls a frequency of a drive current that drives the compressor (hereinafter referred to as a drive frequency), and the drive control unit is capable of controlling the drive frequency at least by a power failure startup control or a normal control;
a temperature estimation unit that estimates an air conditioner side temperature from the temperature detected by the room temperature sensor by utilizing a difference between a temperature detected by the room temperature sensor and a temperature detected by the air conditioning temperature sensor when the compressor is operating under the normal control,
The power failure startup control is a control executed when power supply is restored after power supply is stopped,
The normal control is a control that is executed after the power failure startup control is terminated, and is a control that adjusts a drive frequency so that a detected temperature of the air conditioning temperature sensor becomes a preset temperature,
The temperature estimated by the temperature estimation unit as the air conditioner side temperature when the power supply is restored is defined as the estimated air conditioner side temperature, and the temperature detected by the air conditioner temperature sensor when the power supply is stopped is defined as the stopped air conditioner side temperature,
The temperature difference is the difference between the estimated air conditioner side temperature and the air conditioner side temperature when it is stopped. The power outage time is the time from when the power supply is stopped to when the power supply is restored.
An air conditioning device, wherein the drive control unit determines at least an acceleration of a drive frequency using a temperature difference and a power outage duration, and the power outage startup control is a control for increasing the drive frequency at the determined acceleration. In an air conditioner using a refrigerator having an electric compressor,
a heat exchanger that cools or heats air drawn from a space to be air-conditioned and supplies the air to the space to be air-conditioned;
a room temperature sensor that detects an air temperature in a space to be air-conditioned and that is supplied with power from an uninterruptible power supply at least during a power outage;
an air conditioner temperature sensor that detects the air temperature before heat exchange in the heat exchanger or the air temperature after heat exchange in the heat exchanger (hereinafter, these temperatures are referred to as air conditioner side temperatures);
A drive control unit that controls a frequency of a drive current that drives the compressor (hereinafter referred to as a drive frequency), and the drive control unit is capable of controlling the drive frequency at least by a power failure startup control or a normal control;
a temperature estimation unit that estimates an air conditioner side temperature from the temperature detected by the room temperature sensor by utilizing a difference between a temperature detected by the room temperature sensor and a temperature detected by the air conditioning temperature sensor when the compressor is operating under the normal control,
The power failure startup control is a control that is executed when power supply is restored after power supply is stopped, and has at least three startup control patterns,
The normal control is a control that is executed after the power failure startup control is terminated, and is a control that adjusts a drive frequency so that a detected temperature of the air conditioning temperature sensor becomes a preset temperature,
The temperature estimated by the temperature estimation unit as the air conditioner side temperature when the power supply is restored is defined as the estimated air conditioner side temperature, and the temperature detected by the air conditioner temperature sensor when the power supply is stopped is defined as the stopped air conditioner side temperature,
The temperature difference is the difference between the estimated air conditioner side temperature and the air conditioner side temperature when it is stopped. The power outage time is the time from when the power supply is stopped to when the power supply is restored.
A first start-up control pattern among the three start-up control patterns is a start-up control that is executed when the temperature difference is less than a predetermined value and the power outage time is equal to or longer than a predetermined time,
A second startup control pattern among the three startup control patterns is a startup control that is executed when a temperature difference is equal to or greater than a predetermined value, and is a startup control that increases and changes a drive frequency at a rate greater than that of the first startup control pattern.
The third startup control pattern of the three startup control patterns is a startup control that is executed when the temperature difference is less than a predetermined value and the power outage duration is less than a predetermined time, and is a startup control that increases the drive frequency at an acceleration slower than the first startup control pattern, or a startup control that ends when the drive frequency reaches a predetermined drive frequency that is lower than the drive frequency at the end of the first startup control pattern. An air conditioner according to claim 1 or 2, wherein the room temperature sensor detects the temperature of air before it is heated by a heating element disposed in the space to be air-conditioned.

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