JP2854126B2 - Air conditioner driven by 2 power supplies - Google Patents

Description

The present invention relates to an air conditioner which can be driven by using a commercial AC power supply and another DC power supply at the same time.

(B) Conventional technology As a conventional dual power supply type air conditioner. Showa 56
There was one such as described in -146847. The one described in this publication is provided with a commercial AC power supply and a DC power supply (solar cell power supply) so that the air conditioner can be driven using either the commercial AC power supply or the DC power supply. Met.

(C) Problems to be Solved by the Invention In such a conventional technique, when the output of the DC power source is small and it is not sufficient to operate the air conditioner, the air conditioner is operated using a commercial AC power supply. When the output of the DC power source is sufficient, the operation of the air conditioner is performed using the output of the DC power source.

That is, only one of the commercial AC power supply and the DC power supply is always used for the operation of the air conditioner. For this reason, when the output of the DC power source is low, the output is cut off, the efficiency of use of the DC power source is reduced, and the DC power source cannot be used to the maximum.

To solve such a problem, the one described in JP-A-62-221013 has been attempted. In this publication, a commercial AC power supply and a DC power supply (solar cell) are used in combination, and when the output of DC power is reduced, the shortage from the commercial AC power supply is compensated for to operate the compressor. However, the technique described in this publication cannot sufficiently protect the compressor when an overcurrent flows. For example, when an overcurrent to a compressor is considered (the compressor itself is provided with a bimetal overcurrent protection device, but has a problem that operation is slow with respect to a sudden increase in current. )) As a method of directly detecting the current flowing through the compressor, a shunt resistor may be inserted into the DC circuit to detect the current. However, when the current flowing through the compressor is large, the voltage drop due to the shunt resistor is large. There was a point. When detecting the alternating current supplied to the compressor using a CT (current transformer),
Since this AC is generally an AC with a pseudo sine wave, CT
The distortion of the current waveform detected in step (1) is so large that the sensitivity of current detection cannot be increased. That is, there has been a problem that the reaction is delayed when the current is rapidly increased. This problem also occurs when a shunt resistor is used.

Therefore, a method of providing a CT on the primary side of a commercial AC power supply and detecting a current has been generally used. In this case, the method is suitable for a single power supply drive type using a commercial AC power supply.
The dual-power-supply type using electric power from another system has a problem that a correct current value cannot be detected.

In order to solve such a problem, the present invention is designed to detect an inflow current from each power supply to perform appropriate current detection.

(D) Means for Solving the Problems The present invention provides a DC power obtained by combining DC power obtained by rectifying and smoothing AC power supplied from a commercial AC power supply and DC power supplied from a DC power source. The AC power is converted into AC power having a frequency of and supplied to the AC compressor, and the frequency is changed to change the capacity of the AC compressor. An AC current detector for detecting an AC current, a DC current detector for detecting a DC current supplied from the DC power source, a current detected by the AC current detector, and a current detected by the DC current detector. And a protection unit for changing the frequency of the AC power supplied to the AC compressor so that the sum does not exceed a predetermined value.

Further, the DC power obtained by rectifying and smoothing the AC power supplied from the commercial AC power supply and the DC power supplied from the DC power source are converted into an arbitrary voltage and supplied to the DC compressor. A two-power-supply-type air conditioner configured to change the capacity of the AC compressor by changing the voltage, including an AC current detector and a DC current detector in the same manner as described above; And a protection unit for changing a DC voltage applied to the power supply.

In addition, it has an AC current detector and a DC current detector in the same manner as described above, and further, when supplying the AC having the arbitrary frequency to another AC load, the current detected by the AC current and the DC current detection are supplied. And a protection unit for interrupting the supply of AC power to another AC load when the sum of the current detected by the unit and the current exceeds a predetermined value.

(E) Function In the air conditioner of the dual power supply type configured as described above, the AC compressor supplies the air based on the sum of the current detected by the AC current detector and the current value detected by the DC current detector. It changes the frequency of the AC power.

Further, the voltage of the DC power supplied by the DC compressor is changed based on the sum of the current detected by the AC current detector and the current value detected by the DC current detector.

When supplying AC power to another AC load, when the sum of the current detected by the AC current detector and the current value detected by the DC current detector exceeds a predetermined value, the AC power is supplied to another AC load. This shuts off the supply of AC power.

(F) Embodiment Hereinafter, an embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a main part electric circuit diagram of an air conditioner of a two-power supply type showing an embodiment of the present invention (mainly an outdoor unit). FIG. In this figure, reference numeral 1 denotes an indoor unit, which is connected to a microprocessor 2 of the outdoor unit via a serial signal circuit 3 and a signal line so that control data can be transmitted and received. The data sent from the indoor unit 1 includes a frequency signal F that determines the frequency of AC power by a pseudo sine wave supplied to the compressor, a cooling / heating signal (a signal for switching a four-way valve), and the like. Conversely, the data sent to the outdoor unit (from the microprocessor 2 to the indoor unit 1) includes the outside air temperature data, the frequency of the AC power currently being output, and data indicating an abnormality when the outdoor unit is in an abnormal state. is there. Reference numerals 4 to 6 denote a single-phase induction motor for driving a fan provided to blow air to the outdoor heat exchanger, and a part for returning a part of the high-temperature refrigerant discharged from the compressor to the evaporator during the heating operation. An electromagnetic valve that opens the bypass pipe, and a four-way valve that switches between the cooling operation and the heating operation by reversing the refrigeration cycle, and is connected between the power supply buses of the commercial AC power supply. An opening / closing contact 7 and a switching contact 8 are connected in series to the induction motor 4. By switching the switching piece 8, the rotation speed of the induction motor 4 can be changed in two stages. The operations of the opening / closing contact 7 and the switching contact 8 are controlled by the microprocessor 2. 9 and 10 are photo triacs and their ON / O
The FF is controlled by the microprocessor 2. When the phototriac is turned on / off, the solenoid valve 5 and the four-way valve 6 operate.

Reference numerals 11, 12, and 13 denote temperature sensors, which detect the outside air temperature, the temperature of the outdoor heat exchanger, and the temperature of the compressor 14, respectively. The microprocessor 2 controls the operation of the switching piece 8 based on the outside air temperature and the temperature of the outdoor heat exchanger, and controls the operation of the compressor based on the temperature of the compressor 14 so that this temperature does not exceed a predetermined value.
It is to reduce the frequency of the AC power supplied to 14.

Reference numeral 15 denotes a commercial AC power supply, and the AC power supplied from the power supply is a current fuse 26, a varistor 16, and a noise filter.
17, is supplied to a rectifier circuit (diode bridge) 19 via a choke coil 18. In the rectifier circuit 19, AC power (AC power having an effective value of 100 V) supplied from the commercial AC power supply 15 is double-voltage rectified together with the capacitors 20 and 21 to obtain DC power of 280V. 22 is a noise filter, and 23 is a smoothing capacitor. 24 is a current fuse. Reference numeral 25 denotes an inverter circuit, which includes six switching elements (transistors and the like) connected in a three-phase bridge and a drive circuit for individually turning on / off these switching elements. The drive circuit controls ON / OFF of a switching element according to a switching signal from the microprocessor 2. Accordingly, each switching element of the inverter circuit 25 is turned ON / OFF by a signal from the microprocessor 2. The microprocessor 2 outputs a switching signal to the inverter circuit 25 so that the AC power of the frequency signal given from the indoor unit is supplied to the compressor 14. This switching signal is a switching signal calculated by the microprocessor 2 based on the PWM theory. Therefore, an AC power of an arbitrary frequency (AC by a pseudo sine wave) can be supplied to the compressor 14. It goes without saying that the capacity of the compressor can be changed by changing the frequency of the AC power.

Reference numeral 26 denotes a switching power supply for reducing 280 V DC power to a low voltage necessary for driving the microprocessor 2 and other electronic circuits. In addition, 27 is a current fuse.

28 is a solar panel (an example of a DC power source, which may be replaced with a DC power source such as a battery)
For example, the maximum output is about 600W. (In this embodiment, the compressor
It is about 1/3 of the maximum power consumption of 14 and is set appropriately according to the maximum power consumption.) 29 is a DC / DC converter, which reduces (or boosts) the output from the solar panel 28 to 290V Is what you do. Therefore, the output voltage of this DC / DC converter is always maintained at 290V. Reference numeral 30 denotes a diode for preventing backflow, and when the output of the solar cell panel decreases, or when the power consumption of the compressor 14 increases and the output of the solar cell panel 28 becomes insufficient, the DC power by the This is to prevent backflow to the battery panel 28.

Reference numeral 31 denotes a CT (current transformer) (AC current detector), which detects the current of AC power supplied to the rectifier circuit 19, that is, the primary side AC current of the commercial AC power supply. The current detected by the CT is supplied to the microprocessor 2 via the AC current input circuit 32.

Reference numeral 33 denotes a direct current detector which detects a direct current supplied from a DC / DC converter. This detector 33
Uses a Hall sensor, detects the magnitude of a magnetic field generated by a direct current flowing through a power line, converts this magnetic field into a current, and outputs the current. Therefore, a direct current can be detected without inserting a shunt resistor in the power line. The current detected by the DC current detector 33 is supplied to the microprocessor 2 via a DC current input circuit.

In the outdoor unit of the air conditioner configured as described above, the microprocessor 2 detects the current I _C detected by C.T31.
Based on the detected current I _T of the DC current detector 33 and the second
The operation shown in the flowchart of FIG. At this time current and I _C and the current I _T used in computing the current value when the detection voltage unified in different for either voltage. In the flowchart, initialization of the microprocessor 2 is performed in step S1. Next, in step S2, it is determined whether control data has been received from the indoor unit 1. If control data has been received, the frequency signal F from the indoor unit 1 and the current signal are supplied to the compressor in step S3. The magnitude relationship with the frequency f of the AC power is determined. Step when F ₀ > f
The process proceeds to S5 f = f + 1 (i.e., is to increase the frequency of the AC power output to the compressor) is performed, F ₀ <when f proceeds to step S6 f = f-1 (i.e., the AC output to the compressor Power frequency), then again F ₀ =
In the case of f, the process proceeds directly to step S7. In step S7, the AC current I _C and the DC current I _T are input and the sum I
Ask for. Then step S, 8 step S9, step
The magnitude relationship between the value of I and the predetermined values I1, I2, I3 is determined based on S10. (There is a relation of I1>I2> I3.) When I> I1, the process proceeds to step S11, and f = 0 is set. That is, the operation of the compressor is stopped. Step S12 when I1 ≧ I> I2
To set f = f−2. That is, f set in the previous step is reduced. At this time, since the decrease is set to be larger than the increase of f set in step S5, the output frequency f is substantially reduced. When I2 ≧ I> I3, the process proceeds to step S13, and f = f−1 is set. That is, f set in the previous step is reduced. At this time the increment of the set f in step S5 and the decrease is equal to keep the current value regardless of the value of the frequency F ₀ without substantially f increases.
After correcting the value of f based on the current I in this manner, the process proceeds to step S14. In step S14, the value of f is corrected based on the temperature of the compressor detected by the temperature sensor 13. This correction performs control such as f = 0, reduction of f, and inhibition of increase of f in accordance with the temperature of the compressor.

Next, the process proceeds to step S15, in which the induction motor 4 for blowing air, the solenoid valve 5, the four-way valve 6, etc. are controlled. At this time, control data is also transmitted to the indoor unit 1. After these operations, the process proceeds to step S16, where a switching signal is output to the inverter circuit 25 so that AC power at the frequency f is supplied to the compressor 14. After the output of the AC power of this frequency f is maintained for a predetermined time (about one second), the process returns to step S2 again, and these steps S are repeated thereafter.

By changing the frequency of the AC power output to the compressor based on the AC current I _C and the DC current I _{T in} this manner, when the current flowing through the compressor is I> I1, the operation of the compressor is stopped. When I1 ≧ I> I2, the frequency of the AC power supplied to the compressor is reduced to reduce the current flowing through the compressor, and I2 ≧ I> I3
In this case, the frequency of the AC power supplied to the compressor is prevented from increasing, and the current flowing through the compressor is prevented from increasing.

FIG. 3 is an electric circuit diagram of an air conditioner showing another embodiment of the present invention. This figure differs from the electric circuit diagram shown in FIG. 1 in that a DC brushless motor is used for the compressor. The description of the same components as those shown in FIG. 1 will be omitted. Reference numeral 40 denotes a compressor driven by a three-phase DC brushless motor.
The energization of each phase is switched according to the rotation angle of 40. Reference numeral 41 denotes a switching power supply, whose output is supplied to the inverter circuit 25. This output voltage is controlled by a signal from the microprocessor 2. Reference numeral 42 denotes an energization switch, which calculates a rotation angle of the compressor 40 which detects a change in DC voltage (changes due to a back electromotive force generated by a permanent magnet) applied to each phase of the compressor 40, and calculates the rotation angle. It controls the ON / OFF of the switching elements of the inverter circuit 25 so that the combined phases can be energized. The energization switch 42 starts its operation in response to a signal from the microprocessor 2. Therefore, when the energization switch 42 is operating, the rotation speed of the compressor, that is, the capacity, can be changed by controlling the output voltage of the switching power supply 41.

In the outdoor unit of the air conditioner configured as described above, the operation of the microprocessor 2 is almost the same as the operation described in the flowchart shown in FIG. The difference is that the frequency changes to the rotation speed, and the operation in step S16 changes to "output a signal for outputting a DC voltage to obtain the rotation speed of f to the switching power supply 41".
Actually, since the signal of the frequency F is sent from the indoor unit 1, the process is performed with the frequency from step S2 to step S12, and the number of times corresponding to the frequency is obtained by calculation in step S13. A signal for outputting a voltage at which the rotation speed is obtained is output to the switching power supply 41.

Thus, by changing the voltage of the DC power output to the compressor based on the AC current I _C and the DC current I _T and changing the rotation speed of the compressor, when the current flowing through the compressor is I> I1, Stops the operation of the compressor, reduces the voltage of the DC power supplied to the compressor when I1 ≧ I> I to reduce the current flowing through the compressor, and supplies the compressor when I2 ≧ I> I3 This prevents an increase in the DC power voltage, thereby preventing an increase in the current flowing through the compressor.

FIG. 4 is an electric circuit diagram of an air conditioner showing still another embodiment. The difference from the electric circuit diagram shown in FIG.
5252 to the compressor 14. still,
The switching operation of the switching contacts 50 to 52 is controlled by the microprocessor 2.

Accordingly, by switching the switching contacts 50 to 51, it is possible to switch between supplying the AC power output from the inverter circuit 25 to the compressor 14 or supplying the AC power from the terminal ACOUT to another AC load. When the switching contacts 50 to 52 are on the compressor 14 side (the state shown in FIG. 4), the electric circuit is substantially the same as the electric circuit shown in FIG.
The operation based on the flowchart shown in FIG. 2 is performed.

The operation of the microprocessor 2 when the switching pieces 50 to 52 are on the ACOUT side is as follows.
(If the frequency of the commercial AC power supply is in the region of 50 Hz). ”Further, steps S9 to S13 are deleted so that the current supply to other loads is cut off when the current value exceeds a predetermined value. Next, the microprocessor 2 supplies an ON / OFF signal to the switching element such that single-phase AC power is obtained from the inverter circuit 25. When obtaining single-phase AC power, a single-phase AC power is used. Since a bridge (a bridge composed of four switching elements) is sufficient, four switching elements are selected from the six switching elements of the inverter circuit 25 so that single-phase AC power can be obtained from the switching contacts 51 and 52. Thus, the microprocessor forms these four-phase bridges.
The ON / OFF control of the two switching elements is performed, and the remaining two switching elements are maintained OFF.

In the air conditioner configured as described above, control can be performed within a predetermined value flowing to another load as in the above-described embodiment, and it is possible to prevent an overcurrent from flowing to the inverter circuit 25 and destroy the switching element. Can be.

In the above embodiment, the current I1 for interrupting (stopping) the output from the inverter circuit 25 is set based on the allowable current of the inverter circuit 25.

Further, when there is a limit to the current supplied from the commercial AC power source as another embodiment, to limit the capacity of the compressor (the frequency f of the AC power) based on the alternating current I _C that detects the AC current detector 31 . FIG. 5 is this flowchart, which is added before step S14 in the flowchart shown in FIG. In this flowchart, step S51
AC current I detected by the AC current detector 31 in step S53
Step C by comparing _C with currents I4, I5, I6 (I4>I5> I6)
54 to step S57 are performed. In step S54, f
= 0, the supply of AC power to the compressor is stopped. That is, the current I _C from the commercial AC power source that does not exceed the current I4. In step S55, f = f-2 is performed to reduce the frequency supplied to the compressor. At this time, if the operations of step S12 and step S13 are performed, the frequency f is 4 or 3.
Is to reduce. In step S56, the current I determines that I> I3, and determines whether the previous step S13 has been performed. If step S13 has been performed, then in step S57 f
= F-1 is not performed. Also, if not, step
By performing S57, the frequency f is reduced by one. That is, step S53
Is satisfied, the frequency f is not reduced and the increase in the frequency f is prohibited.

With this configuration, the maximum current can be obtained from the commercial AC power supply, and the current and the current from the solar cell panel can be supplied to the compressor together.

Specifically, when such an air conditioner is set in a general home, the current that can be supplied from a commercial AC power supply to the air conditioner is limited to 20A. (The unit of one breaker is 20A.) Therefore, the compressor can only supply a maximum of 20A, but by providing a solar panel, the current supplied from the solar panel can be added to 20A, It is possible to use a compressor having a large maximum capacity. In other words, while using the current from the commercial AC power supply and the current from the solar panel together, the operating capacity (consumption) of the compressor so that the current from the commercial AC power supply does not exceed 20A (when I4 = 20A) Power) can be controlled. Incidentally, it is needless to say that the control by the sum and the current I _C and the current I _T have been made to fit.

(G) Advantages of the Invention As described above, the present invention provides a DC power obtained by combining DC power obtained by rectifying and smoothing AC power supplied from a commercial AC power supply and DC power supplied from a DC power source. The AC power is converted into AC power having a frequency of and supplied to the AC compressor, and the frequency is changed to change the capacity of the AC compressor. An AC current detector for detecting an AC current;
A DC current detector for detecting a DC current supplied from the DC power source, and the sum of the current detected by the AC current detector and the current detected by the DC current detector does not exceed a predetermined value. The protection unit that changes the frequency of the AC power supplied to the AC compressor can reduce the current supplied to the AC compressor to a predetermined value or less, and prevent damage to the AC compressor due to overcurrent. Can be.

When a DC compressor is used, the DC voltage supplied to the DC compressor is changed by the protection unit, so that the DC compressor can be prevented from being damaged by overcurrent.

Further, even when the AC power is supplied to another load, the output of the AC power can be suppressed to prevent damage at the time of conversion to the AC power.

[Brief description of the drawings]

FIG. 1 is a main part electric circuit diagram of a two-power-supply type air conditioner showing an embodiment of the present invention, FIG. 2 is a flowchart showing main operations of a microprocessor shown in FIG. 1, and FIG. FIG. 4 is an electric circuit diagram of an air conditioner showing another embodiment of the present invention, FIG. 4 is an electric circuit diagram of an air conditioner showing still another embodiment of the present invention, and FIG. It is a flowchart shown. 1 ... indoor unit, 2 ... microprocessor, 14 ...
… Compressor, 15… Commercial AC power supply, 25 …… Inverter circuit, 28 …… Solar panel, 29 …… DC / DC converter, 3
1 …… AC current detector, 33 …… DC current detector, 41 ……
Switching power supply, 50-52 ... Switching contact.

──────────────────────────────────────────────────続 き Continued on front page (58) Field surveyed (Int.Cl. ⁶ , DB name) F24F 11/02

Claims (3)

(57) [Claims] A DC power obtained by combining DC power after rectifying and smoothing AC power supplied from a commercial AC power supply and DC power supplied from a DC power source is converted into AC power of an arbitrary frequency. An AC current detector for detecting an AC current supplied from the AC power supply in a dual power supply type air conditioner supplied to an AC compressor and changing the frequency to change the capacity of the AC compressor. A DC current detector that detects a DC current supplied from the DC power source, and a sum of a current detected by the AC current detector and a current detected by the DC current detector does not exceed a predetermined value. And a protection unit for changing the frequency of AC power supplied to the AC compressor. 2. A DC compressor, comprising: converting DC power obtained by combining DC power obtained by rectifying and smoothing AC power supplied from a commercial AC power supply and DC power supplied from a DC power source into an arbitrary voltage; And an AC current detector for detecting an AC current supplied from the AC power supply in a dual power supply type air conditioner configured to change the voltage to change the capacity of the AC compressor. A direct current detector for detecting a direct current supplied from a direct current power source, and the direct current so that the sum of the current detected by the alternating current detector and the current detected by the direct current detector does not exceed a predetermined value. An air conditioner driven by two power supplies, comprising: a protection unit that changes a voltage of DC power applied to a compressor. 3. A DC power, which is a combination of DC power obtained by rectifying and smoothing AC power supplied from a commercial AC power supply and DC power supplied from a DC power source, is converted into AC power of an arbitrary frequency. In the two-power-supply type air conditioner, which supplies the AC power to the AC compressor and changes the frequency to change the capacity of the AC compressor, the AC power of the arbitrary frequency is supplied to another AC load. A frequency fixing unit for fixing the frequency of the AC power, an AC current detector for detecting an AC current supplied from the AC power supply, and a DC current detector for detecting a DC current supplied from the DC power source And a protection unit for interrupting supply of AC power to another AC load when the sum of the current detected by the AC current detector and the current detected by the DC current detector exceeds a predetermined value. Characterized by Power-driven air conditioner.