JPH0875221A - Air-conditioning machine - Google Patents

Abstract

PURPOSE: To utilize a solar battery to the maximum and minimize the utilization of electric power from a commercial power supply. CONSTITUTION: When a necessary power for a compressor driving circuit 14 can not be satisfied by only the power from a solar battery 23 due to the amount of sunshine or the magnitude of a load, a current control circuit 13 controls a driving circuit 34 to change the duty ratio of ON, OFF of a semiconductor switch 28 by one stage whereby the difference of electric power ΔP between an input power P2 of the compressor driving circuit 14 and an input power P1 from a commercial power supply 11 is decided whether it is increased or not before and after the change of a duty ratio while the duty ratio of ON, OFF of the semiconductor switch 28 is changed into the increasing direction. According to this method, the difference of electric powers ΔP is maximized and the ON, OFF of the semiconductor switch 28 is controlled by the duty ratio at this time. In this case, the solar battery 23 generates the maximum electric power and the amount of shortage of the power is supplied from the commercial power supply 11.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an air conditioner using a commercial power source and a solar cell as a power source.

[0002]

2. Description of the Related Art With the improvement of inverter technology, it has become possible to control the compressor at a variable speed even in a home air conditioner, so that it is possible to significantly reduce power consumption and improve comfort.
On the other hand, improvements in manufacturing technology and expansion of the range of use have made it possible to reduce the price of solar cells and use them as power sources for household appliances. For these reasons, solar cells have come to be used as a power source for air conditioners.

Further, since the inverter device used for variably controlling the compressor uses a capacitor input type of rectifying and smoothing circuit, there is a problem that the power factor decreases, but a reactor is provided. It is also possible to improve the power factor by controlling the input current of the rectifying and smoothing circuit by using a semiconductor switch to approximate the sine wave.

As a power source of an air conditioner in which a compressor can be controlled at a variable speed, a solar cell is also used, for example, one described in Japanese Patent Laid-Open No. 62-221014.

This is because the rectifying / smoothing circuit is provided with a reactor for improving the power factor and a semiconductor switch, and the input current of the rectifying / smoothing circuit is approximated by a sine wave approximation by turning on / off the semiconductor switch. The batteries are connected in parallel so that the power from the rectifying / smoothing circuit and the power from the solar cell are supplied to the inverter device, which is the drive circuit of the compressor.

Then, in such a configuration, the input voltage of the inverter device is detected and compared with the DC reference voltage, and the semiconductor switch is turned on and off so that they match. Here, this DC reference voltage is a voltage (optimal operating voltage) at which the solar cell produces the maximum output. That is, the output voltage of the rectifying / smoothing circuit is controlled by controlling the on / off of the semiconductor switch so that the input voltage of the inverter device is always equal to the optimum operating voltage of the solar cell.

Therefore, when the input voltage of the inverter device is lower than the DC reference voltage, the ON / OFF of the semiconductor switch is controlled to increase the output voltage of the rectifying / smoothing circuit, and the input voltage of the inverter device becomes the DC reference voltage. Try to be equal. This means that the power supply from the solar cell to the inverter device is insufficient, and the insufficient power is supplied from the rectifying and smoothing circuit.
Further, when the input voltage of the inverter device is higher than the DC reference voltage, the ON / OFF of the semiconductor switch is controlled to lower the output voltage of the rectifying / smoothing circuit so that the input voltage of the inverter device becomes equal to this DC reference voltage. To
This means that the power supply from the solar cell to the inverter device is excessive, and this surplus power is regenerated to the commercial power source via the rectifying and smoothing circuit.

[0008]

In the above prior art, the output voltage of the rectifying / smoothing circuit is controlled so that the input voltage of the inverter device is always equal to a constant DC reference voltage. The DC reference voltage is the output voltage of the solar cell when the solar cell generates the maximum power, that is, the optimum operating voltage of the solar cell.

However, the voltage-current characteristics of a solar cell differ depending on the amount of light (hereinafter referred to as the amount of sunshine) from a light source such as the sun, and therefore the voltage generated by the solar cell when the solar cell generates maximum power, that is, The optimum operating voltage also varies depending on the amount of sunlight.

An example of this will be described with reference to FIG. 5, in which the voltage-current characteristics of the solar cell are A, B, depending on whether the amount of sunlight is large, medium or small.
Different like C. When the voltage and current at the time of maximum power generation in the characteristic curve A are V3 and I3, the voltage and current at the time of maximum power generation in the characteristic curve B are V2 and I2.
Respectively, V2 <V3, I2 <I3, and the voltage and currents V1, I1 at the time of maximum power generation in the characteristic curve C become V1 <V2, I1 <I2, respectively.

As described above, since the output voltage of the solar cell when the maximum power is generated varies depending on the amount of sunlight, the input voltage of the inverter device is controlled so as to be equal to a constant DC reference voltage as in the above-mentioned prior art. Then, even if this DC reference voltage is set to the optimum operating voltage of the solar cell,
Depending on the amount of sunlight, the voltage generated when the solar cell generates the maximum electric power is considerably different from the DC reference voltage, so that the solar cell cannot be used in the state where the maximum electric power is generated.

[0012] When the solar cell is used in a state where the maximum output is generated, the solar cell is used with the maximum efficiency. Therefore, the power generated by the solar cell is insufficient for the inverter device, and the commercial power is not available. In the case of supplementing this shortage of electric power from the power supply, the above-mentioned conventional technique cannot always use the solar cell with maximum efficiency, and the solar cell cannot be effectively used.

An object of the present invention is to provide an air conditioner which solves such a problem and can always effectively use a solar cell.

[0014]

In order to achieve the above object, the present invention relates to an air system in which a solar cell is connected in parallel with a rectifying / smoothing circuit of a commercial power source to supply electric power to a drive circuit of a compressor. In the harmony machine, the output power of the rectifying / smoothing circuit is controlled so that the power difference between the input power of the drive circuit of the compressor and the input power of the rectifying / smoothing circuit is maximized.

Further, the present invention detects the maximum power difference by sequentially changing the output power of the rectifying and smoothing circuit.

[0016]

The electric power of the difference between the input electric power of the drive circuit of the compressor and the input electric power of the rectifying and smoothing circuit is the electric power supplied from the solar cell, and this maximum electric power difference means that It means that maximum power is supplied. Therefore, the solar cell can be used at the maximum efficiency point, and the solar cell can be effectively used.

In addition,

[0018]

Embodiments of the present invention will be described below with reference to the drawings. First, the overall configuration of the air conditioner according to the present invention will be described with reference to FIG. Here, 1 is an indoor unit, 2 is an outdoor unit, 3 is a compressor, 4 is an indoor heat exchanger, 5 is an outdoor heat exchanger, 6 is a switching valve, 7 is a pressure reducer, 8 is an electric motor, and 9 is an indoor blower. 10 is an outdoor blower, 11 is a commercial power supply, 12 is a rectifying / smoothing circuit, 13 is a current limiting circuit, 14 is a compressor drive circuit, 15 is an outdoor control circuit, 16 is a DC power supply circuit, 17 is an indoor control circuit, and 18 is Switching valve drive circuit, 19 is an outdoor blower drive circuit, 20 is an indoor blower drive circuit, 21-a, 2
1-b is a modulation / demodulation circuit, 22 is a connection line, 23 is a solar cell,
24 is a reverse blocking circuit.

In the figure, the compressor 3 and the outdoor heat exchanger 5
The decompressor 7 and the indoor heat exchanger 4 form a refrigeration cycle. During the heating operation, the outdoor fan 1 blows the refrigerant in the outdoor unit 1 so that the refrigerant discharged from the compressor 3 has the outdoor heat. The heat is absorbed from the outside air by the exchanger 5, compressed by the compressor 7, and supplied to the indoor heat exchanger 4 in the indoor unit 1. In this indoor heat exchanger 4, the heat of the refrigerant is radiated indoors by the indoor blower 9 blowing air. The heat-dissipated refrigerant returns to the outdoor heat exchanger 5 by the compressor 3. By circulating the refrigerant in this manner, warm air is sent from the indoor heat exchanger 1 into the room to perform heating. In the case of cooling, the operation of the switching valve 6 causes the indoor heat exchanger 4 to absorb heat of the refrigerant and the outdoor heat exchanger 5 to radiate the refrigerant.

In the outdoor unit 2, commercial AC is supplied from the commercial power supply 11, and the rectifying / smoothing circuit 12 forms a DC voltage. Further, a solar cell 23 is connected in parallel to the rectifying / smoothing circuit 12 via a reverse blocking circuit 24, and the electric power from the solar cell 23 and the electric power from the rectifying / smoothing circuit 12 are supplied to the compressor drive circuit 14. When supplied, the electric motor 8 of the compressor 3 is driven. Here, the reverse blocking circuit 24 prevents the reverse flow of current from the rectifying / smoothing circuit 12 to the solar cell 23.

The DC voltage from the solar cell 23 and the rectifying / smoothing circuit 12 becomes the power supply voltage of the switching valve drive circuit 18 and the outdoor blower drive circuit 19 controlled by the outdoor control circuit 15, and the direct current power supply circuit 16 receives the DC voltage. Is also supplied to form a predetermined low voltage. This low voltage is applied to the modulation / demodulation circuit 2
It is supplied to the indoor unit 1 via 1-b and the connection line 22. In the indoor unit 1, this voltage is supplied as a power supply voltage to the indoor control circuit 17, the indoor blower drive circuit 20, etc. via the modulation / demodulation circuit 21-a.

Here, communication can be performed between the indoor unit 1 and the outdoor unit 2 via the connection line 22. That is, when a user operates an operation unit (not shown) provided in the indoor unit 1, a command for starting the air conditioner, setting a temperature, or the like is given, and information such as an indoor temperature is given by a temperature sensor or the like. The indoor control circuit 17 generates an information signal based on the command and the information. This information signal is supplied to the modulation / demodulation circuit 21-a, a high frequency carrier is modulated to form a transmission signal, and the transmission signal is superimposed on the DC voltage of the connection line 22. As a result, this transmission signal is transmitted to the outdoor unit 2 via the connection line 22. In the outdoor unit 2, this transmission signal is separated from the DC voltage by the modulation / demodulation circuit 21-b and received,
The information signal is demodulated and sent to the outdoor control circuit 15. The outdoor control circuit 15, based on the received information signal,
The compressor drive circuit 14, the switching valve drive circuit 18, the outdoor blower drive circuit 19 and the like are controlled so that the refrigeration cycle operates according to a command from the indoor unit 1.

The outdoor control circuit 15 also outputs response information to the above information signal from the indoor unit 1 and command information according to the control state of the refrigeration cycle. The information signal is supplied to the modulation / demodulation circuit 21-b, and is transmitted to the indoor control circuit 17 of the indoor unit 1 via the connection line 22 in the same manner as above. The indoor control circuit 17 operates based on the received information signal, controls the indoor blower drive circuit 20 to drive the indoor blower 9 in accordance with the operation of the refrigeration cycle, and controls the indoor unit 1.

FIG. 1 is a block diagram showing an embodiment of an air conditioner according to the present invention, in which 25 is a rectifier, 26 is a reactor, 27 is a diode, 28 is a semiconductor switch, 29 is a smoothing capacitor, and 30a and 30b. Is a current detector, 31
Is a current pattern generation circuit, 32 is a multiplication circuit, 33 is a comparison circuit, 34 is a drive circuit, and 35a and 35b are electric power calculation circuits.

In the figure, the commercial AC from the commercial power supply 11 is rectified by the rectifier 25 and smoothed by the smoothing capacitor 29 to obtain a DC voltage. A reactor 26, a semiconductor switch 28, and a diode 27 are provided between the rectifier 25 and the smoothing capacitor 29. By controlling the semiconductor switch 28 to be turned on and off by a drive circuit 34, the principle of the step-up chopper can be realized. By applying it, the input current is approximated by a sine wave. The DC voltage obtained by the smoothing capacitor 29 is applied to the compressor drive circuit 14 as a power supply voltage, and the DC voltage generated by the solar cell 23 is also applied to the compressor drive circuit 14 as a power supply voltage.

Here, the voltage-current characteristic of the solar cell 23 is such that the amount of sunlight is sufficiently large as shown by the characteristic curve A in FIG.
When the solar cell 23 generates an amount of electric power that sufficiently supplements the electric power required by the compressor drive circuit 14, the drive circuit 34 holds the semiconductor switch 28 in the off state, and the compressor drive circuit 14 includes the solar cell. Only the electric power generated by 23 is supplied. In addition, the voltage-current characteristic of the solar cell 23 is a moderate amount of sunshine as shown by the characteristic curve B in FIG.
4 cannot cover the power required by the solar cell 23,
Is set to the state of the maximum efficiency point that generates the maximum power, and the shortage is supplemented with the power from the commercial power supply 11. Setting the state of the solar cell 23 in this manner can be realized by controlling the duty ratio of the ON / OFF of the semiconductor switch 28 by the drive circuit 34, as described later. Furthermore, in the case where the voltage-current characteristic of the solar cell 23 is such that the amount of sunshine as shown by the characteristic curve C of FIG. 5 is very small and the solar cell 23 cannot be set to the state of the maximum efficiency point,
Regardless of the state of the solar cell 23, the semiconductor switch 28 is controlled to be turned on and off at the maximum duty ratio so that electric power is supplied from the commercial power supply 11 to the compressor drive circuit 14.

In order to perform the control operation for supplementing the shortage of the electric power from the solar cell 23 from the commercial power source 11 as described above,
The semiconductor switch 28 is controlled to be turned on and off so that the difference between the input power P2 of the compressor drive circuit 14 and the input power P1 from the commercial power supply 11 is maximized so that the input current of the rectifier 25, and thus the commercial power supply 11 is reduced. Control the input power P1 from. Here, when the generated power of the solar cell 23 is Ps,
Since Ps = P2-P1, this power difference (P2-P
When 1) is maximized, the maximum power Ps that can be generated is supplied from the solar cell 23, and the solar cell 23 can be set in a state of being used at the maximum efficiency point.

The input power P2 of the compressor drive circuit 14 detects the input voltage of the compressor drive circuit 14, and the current detector 30
It is obtained by detecting the input current of the compressor drive circuit 14 by b, and calculating the input voltage and input current by the power calculation circuit 35b. The input power P1 from the commercial power supply 11 detects the output voltage of the rectifier 25, and the current detector 30a detects the input current of the rectifier 25.
It is obtained by calculating the input voltage and the input current in the power calculation circuit 35a. The current control circuit 13 uses the drive circuit 34 to drive the semiconductor switch 28 so that the calculated power difference (P2-P1) between the powers P2 and P1 is maximized.
Control on and off.

Next, the control operation will be specifically described with reference to FIGS. 3 and 4. However, FIG. 3 is a flow chart showing a change in the operating point (that is, state) of the solar cell 23 in such a control operation, and FIG. 4 is a flowchart showing such a control operation.

Now, for a certain amount of sunlight, the solar cell 23
It is assumed that the voltage-current characteristics of are as shown in FIG. When the air conditioner is not operating, the load on the solar cell 23 is 0, the output voltage of the solar cell 23 at this time is a value Va according to the amount of sunshine at this time, and the output current is 0.
The operating point of the solar cell 23 is a. Further, the semiconductor switch 28 is in the off state, and no power is supplied from the commercial power supply 11.

When the air conditioner starts operating, electric power is supplied from the solar cell 23 and the electric motor 8 starts rotating. At this time, the semiconductor switch 28 is held in the off state, and no power is supplied from the commercial power supply 11. Electric motor 8
3, the load of the compressor drive circuit 14 increases in sequence, and the slope of the load line of the solar cell 23 in FIG. 3 increases. The operating point of the solar cell 23 at which this intersects the characteristic curve is shown in FIG. It changes from a to the arrow X direction along the characteristic curve shown. At the same time, the output voltage of the solar cell 23 is V
The voltage gradually decreases from a, the output current sequentially increases from 0, and the generated power sequentially increases. The load line of the solar cell 23 is represented by a straight line that passes through the origin of FIG. 3 and has an inclination according to the magnitude of the load. The solar cell 23 has an intersection of the characteristic curve of FIG. 3 and the load line at the maximum load. Therefore, the state becomes stable at the operating point, and therefore, the air conditioner starts to operate, and the state of the solar cell 23 moves toward the operating point for this maximum load from the arrow a on the characteristic curve of FIG. It will change in the X direction.

Here, assuming that the voltage Vf in FIG. 3 is the lower limit voltage of the operable voltage range of the compressor drive circuit 14, the load line of the solar cell 23 shows the operating point a on the characteristic curve and this voltage Vf.
If it intersects with the operating point f at
The state of the solar cell 23 is stabilized so that the operating point of 3 is between these. In such a state, the solar cell 23 alone can supply the electric power required by the compressor drive circuit 14.

Therefore, the current control circuit 13 sets a reference voltage Vg (FIG. 3) which is slightly higher than the lower limit voltage Vf of the operable voltage range of the compressor drive circuit 14, and when the air conditioner starts operating. The input voltage V of the compressor drive circuit 14 detected by the power calculation circuit 35b is compared with the reference voltage Vg, and when V ≧ Vg, it is assumed that the solar cell 23 alone can supply the power required by the compressor drive circuit 14. The semiconductor switch 28 is maintained in the off state as it is.

Therefore, as long as the amount of sunlight is large and the power required by the compressor drive circuit 14 can be covered by the power generated by the solar cell 23, the semiconductor switch 28 remains off after the start of the operation of the air conditioner. Therefore, as the solar cell 23, the lower limit voltage Vf of the operable voltage range of the compressor drive circuit 14 such as the operating points b, c, d, and e is set according to the load of the solar cell 23.
Therefore, the electric power from the commercial power supply 11 is cut off, and the electric power is supplied from only the solar cell 23 to the compressor drive circuit 14. This is step 400 in FIG. 4 when the air conditioner starts operating.

When the amount of sunlight is small and the solar cell 23 alone cannot cover the electric power required by the compressor drive circuit 14, the operating point of the solar cell 23 is on the characteristic curve a of FIG. Although it changes in the direction of arrow X from, the voltage finally reaches the operating point g of Vg after exceeding the maximum efficiency point d. Since the voltage at this time is Vg (that is,
Since V = Vg), the current control circuit 13 determines that the solar cell 23 alone cannot cover the power required by the compressor drive circuit 14 (step 400 in FIG. 4), and the drive circuit 3
4 to control the semiconductor switch 28 with the minimum duty ratio.
Is turned on and off (step 401 in FIG. 4). As a result, the minimum power is supplied from the commercial power supply 11 to the compressor drive circuit 14.

In this case, the load line of the solar cell 23 intersects with the characteristic curve on the left side of the operating point g, but this minimum power is supplied from the commercial power source 11 as described above, and this power The power that the solar cell 23 bears is reduced, the load line has a gentle slope, and the intersection of the load line and the characteristic curve approaches the operating point g.

Therefore, the current control circuit 13 receives the input power P2 of the compressor drive circuit 14 obtained by the power calculation circuit 35b and the input power P1 of the rectification circuit 25 obtained by the power calculation circuit 35a (that is, from the commercial power supply 11). Power) and
The power difference ΔPa = P2−P1 is calculated and held (step 402 in FIG. 4). Then, the current control circuit 13 controls the drive circuit 34 to increase the ON / OFF duty ratio of the semiconductor switch 28 by one step (step 403 in FIG. 4), and the power P1 detected by the power calculation circuits 35a and 35b at this time. , P2, the power difference ΔPb = P2−P1 is obtained (step 404 in FIG. 4) and held.
Is compared with the detected power difference of this time and ΔPa is the detected power difference of the previous time, and these magnitudes are compared (step 405 in FIG. 4).

When ΔPb> ΔPa, the semiconductor switch 2 is operated in step 403 of FIG.
By increasing the ON / OFF duty ratio of 8 by one step, the power difference (P2-P1), and accordingly, the generated power of the solar cell 23 increases, and the operating point of the solar cell 23 in FIG. This means that it moved in the direction of the arrow Y and approached the maximum efficiency point d.

In this case, the process returns to step 402 of FIG. 4, and the current control circuit 13 again causes the power calculation circuits 35a and 35a.
Incorporating the detected powers P2 and P1 of b, the previously detected power difference Δ
Then, the drive circuit 34 is controlled to further increase the ON / OFF duty ratio of the semiconductor switch 28 by one step, and the power P detected by the power calculation circuits 35a and 35b is calculated.
1, P2, the present power difference ΔPb is obtained (step 404 in FIG. 4), and the magnitude of the previous detected power difference ΔPa and the present detected power difference ΔPb are compared (step 40 in FIG. 4).
5).

Previous detected power difference ΔPa <Current detected power difference Δ
As long as it is Pb, the operations of steps 402 to 405 are repeated, and the operating point of the solar cell 23 moves in the direction of the arrow Y on the characteristic curve and sequentially approaches the maximum efficiency point d.

Thereafter, when the previously detected power difference ΔPa ≧ currently detected power difference ΔPb (step 405 in FIG. 4), the operating point of the solar cell 23 exceeds the maximum efficiency point d,
The current control circuit 13 controls the drive circuit 34 to reduce the ON / OFF duty ratio of the semiconductor switch 28 by one step and set it to the previous duty ratio (step 4 in FIG. 4).
06). As a result, the operating point of the solar cell 23 is set at or near the maximum efficiency point d. In such a state, the solar cell 23 generates the maximum power with the amount of sunshine at that time and supplies it to the compressor drive circuit 14, and the maximum power covers a part of the power required by the compressor drive circuit 14, The remaining part of the required power is supplied from the commercial power source 11 by the ON / OFF duty ratio of the semiconductor switch 28 set as described above. That is, the solar cell 23
Supplies the maximum power that can be generated to the compressor drive circuit 14, and supplements the insufficient power from the commercial power supply 11.

In this way, if the operating point of the solar cell 23 is automatically set to the maximum efficiency point or a point very close to the maximum efficiency point, it is not necessary to repeat the above-mentioned control operation too often. This state is maintained for a predetermined time (step 407 in FIG. 4) to stabilize the operation. The load fluctuation of the air conditioner and the position change of the sun are gradual, and the timer is normally set to several seconds in consideration of the case where the sunlight is blocked by the movement of clouds and the amount of sunshine changes.

When the predetermined time elapses, the current control circuit 13 takes in the powers P2 and P1 detected by the power calculation circuits 35a and 35b, and the previously detected power difference ΔPa = P2-.
P1 is obtained and held (step 408 in FIG. 4), and then the drive circuit 34 is controlled to reduce the ON / OFF duty ratio of the semiconductor switch 28 by one step (step 409 in FIG. 4). As a result, the ON / OFF duty ratio of the semiconductor switch 28 becomes 0, and the power calculation circuit 3
If the power P1 detected in 5a does not become 0 (see FIG. 4).
4), the current control circuit 13 takes in the electric powers P2 and P1 detected by the electric power calculation circuits 35a and 35b and obtains the present detected electric power difference ΔPb = P2-P1 (step 411 in FIG. 4). The relationship between ΔPa and ΔPb is determined (step 412 in FIG. 4).

Here, if the sunshine state and the load state have not changed from those when step 407 is entered, for example, as shown in FIG.
In, when the solar cell 23 is in the sunshine and the characteristic curve is B, the load line of the solar cell 23 is set to L and step 4
If the load line L is not changing due to sunshine even after the above predetermined time has elapsed after entering 07, the operating point of the solar cell 23 before and after step 409 is the arrow from the maximum efficiency point d or its immediate vicinity. Since it moves in the X direction beyond the maximum efficiency point d, the power supplied from the solar cell 23 decreases and ΔPa ≧ ΔPb. Therefore, in this case, the current control circuit 13 shifts to the operation from step 402 in FIG. 4 and sets the operating point of the solar cell 23 at the maximum efficiency point d or in the vicinity thereof as described above (see FIG. 4 step 407).

If the amount of sunshine is reduced or the load is increased when the state of step 407 has passed, for example, in FIG. 407, after the lapse of the predetermined time, when the sunshine becomes small and the characteristic curve of the solar cell 23 is C, the duty ratio of the semiconductor switch 28 is fixed and the power from the commercial power source 11 is constant. Therefore, the load line of the solar cell 23 intersects on the left side of the maximum efficiency point d with the slope substantially increasing in FIG. 3, as is clear from FIG.
It is the operating point of 3.

Therefore, the above steps 408 to 41 in FIG.
When the control operation 1 is performed, the operating point of the solar cell 23 is as shown in FIG.
Since the current detection power difference ΔPa> this time detection power difference ΔPb (step 412 in FIG. 4), the control operation of steps 402 to 405 is performed and the solar cell 23 The operating point is set again at or near the maximum efficiency point d (steps 406 and 407 in FIG. 4). That is, referring to FIG. 5, the load line L is set to intersect with the characteristic curve C at or near its maximum efficiency point.

When the amount of sunshine increases or the load decreases when the state of step 407 elapses, for example, in FIG. 5, step 407 in which the load line L is set as illustrated in the sunshine is shown. After the above predetermined time, when the sunshine becomes large and the characteristic curve of the solar cell 23 is A, the load line of the solar cell 23 intersects with the characteristic curve in FIG. 3 on the right side of the maximum efficiency point d. However, this intersection is the operating point of the solar cell 23 at this time. Therefore, when the control operation of steps 408 to 411 in FIG. 4 is performed,
Since the operating point of the solar cell 23 moves in the arrow X direction on the characteristic curve of FIG. 3, the previously detected power difference ΔPa <the present detected power difference ΔPb (step 412 in FIG. 4). At this time, the current control circuit 13 returns to the operation of step 408 of FIG. 4, and the duty ratio of the ON / OFF of the semiconductor switch 28 becomes 0, and the commercial power source 1 detected by the power calculation circuit 35a.
Unless the power P1 from 1 becomes 0, the operations of steps 408 to 412 in FIG. 4 are repeated, and the previously detected power difference Δ
When Pa ≧ current detected power difference ΔPb, step 4
Move to the operation from 02. As a result, the state of the solar cell 23 is set again so that its operating point becomes the maximum efficiency point d (step 407 in FIG. 4). That is, referring to FIG. 5, the load line L of the solar cell 23 is set to intersect with the maximum efficiency point on the characteristic curve A or in the vicinity thereof.

During the repetition of the operations of steps 408 to 412 of FIG. 4, when the ON / OFF duty ratio of the semiconductor switch 28 becomes 0 and the input power P1 of the rectifier 25 detected by the power calculation circuit 35a becomes 0 (FIG. 4). Step 41
0), the need for the compressor driving circuit 14 and the electric power can be covered only by the solar cell 23, and the process returns to step 400 in FIG. 4 to set the state in which the air conditioner is operated only by the electric power from the solar cell 23.

In this way, during the repetition of the operations of steps 408 to 412, the rectifier 25 detected by the power calculation circuit 35a.
Input power P1 of 0 becomes 0, step 4 of FIG.
When the state of 07 has passed, the load line of the solar cell 23 is in a state where the solar cell 23 can generate electric power more than the electric power required by the compressor drive circuit 14 for the load at that time. The operating point a and the maximum efficiency point d in the characteristic curve of FIG. 3 intersect each other. Then, by repeating the operations of steps 408 to 412 of FIG. 4 as described above, the operating point of the solar cell 23 is changed from this state to the arrow X.
Direction, the semiconductor switch 28 is turned on with a duty ratio of 0 at an operating point between the operating point a and the maximum efficiency point d of the characteristic curve in FIG. 3, and the commercial power supply 11 is no longer supplied with power. Of. In such a state, the solar cell 23 supplies the electric power required by the compressor drive circuit 14.

As described above, in this embodiment, when the solar cell 23 alone cannot supply the electric power required by the compressor drive circuit 14, the solar cell 23 is set to a state in which the maximum electric power is generated. Can be supplemented from the commercial power supply 11, and the power from the commercial power supply 11 can be minimized.

It should be noted that the amount of sunlight is sufficiently small and the maximum efficiency point d
In some cases, the voltage Vd at the lower limit is lower than the operable lower limit voltage Vg of the compressor drive circuit 14. In such a case, the duty ratio for turning on and off the semiconductor switch 28 is maximized, and the commercial power source 1 is used without considering the power from the solar cell 23.
Power is supplied from 1 according to the load. For this reason, in the step before step 400 in FIG.
The control operation of ~ 416 is performed.

That is, when the operation of the air conditioner is started, the change of the input power P2 of the compressor drive circuit 14 is detected by steps 413 and 414 in FIG. 4, and the semiconductor switch 28 is turned off as long as this change is detected. Keep it in the state. At this time, the input voltage V of the compressor drive circuit 14
(This is also the output voltage of the solar cell 23) is also monitored (step 415 of FIG. 4). Then, this input power P2
When the input voltage V becomes equal to or lower than the lower limit voltage Vg (step 415 in FIG. 4) during the increase of, the sunshine amount is sufficiently small,
It is determined that the voltage Vd at the maximum efficiency point d is lower than the operable lower limit voltage Vg of the compressor drive circuit 14, and the duty ratio of ON / OFF of the semiconductor switch 28 is controlled to be Vg = V. Such a state is continued for a predetermined time, and thereafter, the semiconductor switch 28 is held in the off state and the operation is performed again from step 413, so that the semiconductor switch 28 is turned on again depending on whether the sunshine amount has changed. Operate at maximum duty ratio, or step 4
It is possible to automatically select whether to perform a control operation of 00 or less.

Of course, as described above, the lower limit voltage V
When g is lower than the voltage Vd at the maximum efficiency point d, as long as the input power P2 of the compressor drive circuit 14 is increasing, the input voltage of the compressor drive circuit 14 (therefore, the output voltage of the solar cell 23). V never becomes lower than the lower limit voltage Vg. Then, when the input power P2 of the compressor drive circuit 14 starts to decrease, the process moves to step 400 and the above control operation is performed.

In this way, in this embodiment, the air conditioner can be driven only by the solar cell 23 depending on the amount of sunlight and the load, and the solar cell 23 is insufficient as the maximum power generation state. The commercial power source 11 can be used to compensate for this, or the commercial power source 11 alone can be used for driving, and the solar cell 23 can be used effectively to reduce the power from the commercial power source 11. Utilization can be minimized.

In the air conditioner, the waveform of the input current from the commercial power source is preferably a sine wave in order to increase the power factor. For this reason, in this embodiment, in FIG.
Generate a sine wave that matches the phase of 1. Then, in the multiplication circuit 32, the duty ratio determined by the current control circuit 13 is modulated to this sine wave to create a reference current pattern, which is compared with the input current detected by the current detector 30a. The drive circuit 34 controls the on / off of the semiconductor switch 28 so that the two coincide with each other. As a result, the semiconductor switch 28 is turned on / off at the duty ratio determined by the current control circuit 13.

Further, in FIG. 1, since the input power P1 from the commercial power source 11 is obtained from the input current and the output voltage of the rectifier 25, this input power P1 can be obtained very accurately. Input power P1 to rectifier 2
5 and the input voltage of the compressor drive circuit 14, the input power P1 obtained by this
Is not significantly different from the input power P1 obtained as described above, and is not particularly inconvenient. Moreover, in this case, only the detector conventionally used in the air conditioner can be used, and it is not necessary to additionally add a detector for detecting the output voltage of the rectifier 25.

[0057]

As described above, according to the present invention,
If the power of the solar cell is insufficient, you can use this solar cell in the state that generates the maximum power and make up for the shortage from commercial power source. The use of electric power from a commercial power source can be minimized.

[Brief description of drawings]

FIG. 1 is a configuration diagram showing an embodiment of an air conditioner according to the present invention.

FIG. 2 is a block diagram showing an overall configuration of an air conditioner according to the present invention.

FIG. 3 is a diagram for explaining the operation of the solar cell in FIG.

FIG. 4 is a flowchart showing a specific example of the operation of the embodiment shown in FIG.

FIG. 5 is a diagram showing the characteristics of a solar cell according to the amount of sunlight.

[Explanation of symbols]

 8 electric motor 11 commercial power supply 13 current control circuit 14 compressor drive circuit 23 solar cell 25 rectifier 26 reactor 28 semiconductor switch 29 smoothing capacitors 30a, 30b current detector 31 current pattern generation circuit 32 multiplication circuit 33 comparison circuit 34 drive circuit 35a, 35b Power calculation circuit

Claims (5)

[Claims] 1. A motor for driving a compressor that constitutes a refrigeration cycle, a rectifying / smoothing circuit for receiving and rectifying and smoothing a commercial power source, first control means for controlling output power of the rectifying / smoothing circuit, and An air conditioner comprising a solar cell connected in parallel with a rectifying and smoothing circuit, and a drive circuit of the compressor to which at least one of the output power of the rectifying and smoothing circuit and the output power of the solar cell is supplied, Air comprising second control means for controlling the first control means so that the power difference between the input power of the drive circuit of the compressor and the input power of the rectifying and smoothing circuit is maximized. Harmony machine. 2. The second control means according to claim 1, wherein the second control means controls the first control means to sequentially change the input power of the rectifying / smoothing circuit to detect the maximum power difference. An air conditioner characterized by that. 3. The reactor according to claim 1, wherein a reactor is provided on the input side of the rectifying / smoothing circuit, the first control means includes a semiconductor switch, and the input current of the rectifying / smoothing circuit is approximated by a sine wave approximation control. An air conditioner characterized by. 4. The rectifier according to claim 1, 2 or 3, wherein the second control means detects the input power of the drive circuit of the compressor from the input voltage and the input current of the drive circuit of the compressor. An air conditioner that detects the input power of the rectifying and smoothing circuit from the output voltage and the input current of the smoothing circuit. 5. The compressor according to claim 1, 2 or 3, wherein the second control means detects the input power of the drive circuit of the compressor from the input voltage and the input current of the drive circuit of the compressor, An air conditioner that detects the input power of the rectifying and smoothing circuit from the input voltage of the drive circuit of the machine and the input current of the rectifying and smoothing circuit.