JPH05168172A - Power supply device for air conditioner - Google Patents

Abstract

PURPOSE:To prevent the generation of an accident by power generated by a solar cell when a compressor is not operated while reducing the stress of the solar cell at a time when the quantity of the generation of the solar cell is small. CONSTITUTION:When the generated currents of a solar cell panel 28 is small, changeover contacts 40, 41 are changed over when a compressor 14 is stopped, an output from the solar cell panel 28 is short-circuited through a resistor 42, and high voltage from a DC/DC converter 29 is not applied to a power line from a commercial AC power 15 to the compressor 14.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a power supply device for an air conditioner which uses a combination of DC power obtained by rectifying and smoothing AC power from a commercial power source and DC power generated by a solar cell. is there.

[0002]

2. Description of the Related Art A conventional electric power source for driving an electric motor using AC power from a commercial power source and DC power from a solar cell is disclosed in Japanese Utility Model Laid-Open No. 56-146847. There was something. The one described in this publication includes a commercial AC power source and a DC power source (solar cell power source), and a compressor (electric motor) for an air conditioner is installed using either the commercial AC power source or the DC power source. It was designed to be driven.

[0003]

In such a conventional technique, when the output of the DC power source is too small to operate the air conditioner, the air conditioner is operated by using the commercial AC power source. When the output of the power source is sufficient, the output of this DC power source is used to operate the air conditioner.

That is, only one of the commercial AC power source and the DC power source has always been used for operating the air conditioner. For this reason, when the output of the DC power source is small, the output is cut off, the utilization efficiency of the DC power source is lowered, and this DC power source cannot be used to the maximum extent.

With respect to such a problem, Japanese Patent Laid-Open No. 62-62
Those described in Japanese Patent No. 221013 have been tried. The one described in this publication uses a commercial AC power source and a DC power source (solar cell) in combination, and when the output of DC power decreases, the commercial AC power source is used to compensate for the shortage and the compressor operates. Was to do.

With this configuration, the DC power is supplied from the solar cell to the drive circuit of the compressor even when the compressor is not operating, that is, when the air conditioner is not operating. Normally, the DC power used to drive the compressor is about DC 280 [V], and there was a risk that an administrator or a service person would accidentally touch and receive an electric shock during maintenance and inspection.

Further, at this time, since the output voltage of the solar cell is substantially in the open state of 280 [V], the stress applied to the solar cell is large and the life of the solar cell is shortened.

Further, when the generated current of the solar cell is smaller than a predetermined value, the converter circuit cannot sufficiently boost the voltage and the DC power cannot be substantially supplied to the drive circuit, and the compressor is stopped for the solar cell. The stress on the solar cell was increased to the same level as in the above condition.

The present invention addresses these problems by providing a power supply device that is safe when the air conditioner is stopped and that reduces stress on the solar cell.

[0010]

According to the present invention, a rectifying / smoothing circuit for rectifying and smoothing AC power supplied from an AC power source into DC power and outputting the DC power, and converting the DC power into AC power having an arbitrary frequency. In a power supply device for an air conditioner having a drive circuit for supplying to a compressor, a solar cell and DC power generated by the solar cell are converted into DC power having a voltage higher than the voltage of the DC power obtained from the rectifying and smoothing circuit. A DC / DC (direct current / direct current) converter circuit that outputs the current, a current detection circuit that detects a generated current of the solar cell, and a converter circuit when the generated current detected by the current detection circuit is larger than a predetermined value. The DC power output is added to the DC power output from the rectifying / smoothing circuit, and the DC power output from the converter circuit when the current value is smaller than the predetermined value is added. Is obtained by a control circuit for short-circuiting the output of the solar cell causes the disconnection.

The drive circuit supplies DC power to each stator winding of the electric compressor in a predetermined order based on the rotation angle of the compressor.

Further, the control circuit is provided with a safety control circuit for cutting off the DC power output from the converter circuit and short-circuiting the output of the solar cell even when the operation of the air conditioner is stopped.

[0013]

When the power supply device for the air conditioner configured as described above is used, a high voltage DC voltage is not supplied from the solar cell to the drive circuit when the operation of the air conditioner is stopped. Further, when the power generation of the solar cell is not required, the output of the solar cell can be short-circuited to reduce the stress of the solar cell.

[0014]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is an electric circuit diagram of a main part of a separation type air conditioner configured to drive an electric motor for a compressor by using a power supply device showing an embodiment of the present invention (mainly an air circuit diagram of an outdoor unit).
Is.

In the figure, 1 is an indoor unit,
It is connected to the microprocessor 2 of the outdoor unit so that control data can be transmitted and received via the serial signal circuit 3 and the signal line. The indoor unit 1 closes the switch contact pieces 1a and 1b when operating the compressor, and the commercial AC power supply 15
AC power is supplied to the outdoor unit.

The data sent from the indoor unit 1 is a frequency signal F (F = 0 stops the compressor) which determines the frequency of the pseudo sine wave AC power supplied to the compressor.
For example, a heating signal (a signal that switches the four-way valve).

On the other hand, as the data sent from the outdoor unit (microprocessor 2) to the indoor unit 1, the outside air temperature data, the frequency of the AC power currently output (the rotation speed of the compressor electric motor), and the outdoor unit are abnormal. It is data indicating an anomaly when the status is reached.

Reference numerals 4 to 6 are single-phase induction motors (driving capacitors are omitted) for driving fans provided so as to be able to blow air to the outdoor heat exchanger, and high-temperature refrigerant discharged from the compressor during heating operation. Solenoid valve that opens a bypass pipe for returning a part to the evaporator, reverses the refrigeration cycle and performs cooling operation /
It is a four-way valve that switches the heating operation and is connected between the power busbars of the commercial AC power supply.

An open / close contact piece 7 and a switching contact piece 8 are connected in series to the induction motor 4. Switching contact piece 8
By changing over, it is possible to change the rotation speed of the induction motor 4 in two stages of high speed and low speed. The operations of the opening / closing contact piece 7 and the switching contact piece 8 are controlled by the microprocessor 2.

Phototriacs 9 and 10 are turned on / off by the microprocessor 2. The solenoid valve 5 and the four-way valve 6 are energized by turning on / off the phototriac. still,
The microprocessor 2 controls ON / OFF of the photo triacs 9 and 10.

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 rotation speed of the induction motor by switching the switching contact piece 8 based on the outside air temperature and the temperature of the outdoor heat exchanger so that the temperature does not exceed a predetermined value based on the temperature of the compressor 14. In addition, a protection operation is performed to forcibly reduce the frequency of the AC power supplied to the compressor 14.

This compressor 14 has three stator windings 37,
A three-phase induction motor in which 38 and 39 are connected in a star shape is used as a drive source.

AC power supplied from the commercial AC power supply 15 is applied to a rectifier circuit (diode bridge) 19 via a varistor 16, a noise filter 17, and a choke coil 18. In this rectifier circuit 19, the AC power supplied from the commercial AC power supply 15 (AC power having an effective value of 100V) is double-voltage rectified together with the capacitors 20 and 21 to obtain 280V DC power. 22 is a noise filter, 2
Reference numeral 3 is a smoothing capacitor. The rectifying circuit 19 and the smoothing capacitor 23 form a rectifying and smoothing circuit. Incidentally, 24 is a current fuse.

Reference numeral 25 is an inverter circuit (driving circuit), which includes six switching elements (transistors, FETs, IGBTs, etc.) connected in a three-phase bridge shape, and a drive circuit 26 for individually turning ON / OFF these switching elements. And consists of.

The drive circuit 26 is the microprocessor 2
O of the switching element according to the switching signal from
N / OFF is controlled (power of the switching signal from the microprocessor 2 is amplified to such an extent that the switching element can be sufficiently driven). Therefore, each switching element of the inverter circuit 25 is the microprocessor 2
The signal from turns on / off.

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 PWM theory (generated from the magnitude of the carrier wave and the modulation wave of the frequency of the frequency signal).
Is the switching signal calculated by the microprocessor 2 based on

Therefore, the AC power of any frequency (AC power of pseudo sine wave) can be supplied to the compressor 14. It goes without saying that by changing the frequency of this AC power, the rotation speed of the electric motor that drives the compressor changes and the capacity of the compressor can be changed.

Numeral 27 is a switching power supply, which is 280 V
The DC power of is reduced to a low voltage required for the operation of the microprocessor 2 and other electronic circuits.

Reference numeral 28 denotes a solar cell panel (a panel obtained by connecting a plurality of solar cells), and the maximum output is about 600 W, for example. (In this embodiment, it is about 1/3 of the maximum power consumption of the compressor 14, and is set appropriately according to the size of the maximum power consumption.) The DC power generated by the solar cell panel 28 is the switching contact piece 40, When 41 is on the DC / DC converter circuit 29 side, it is supplied to the DC / DC converter, and when it is on the resistor 42 side, it is supplied to the resistor 42. still,
The switching contacts 40 and 41 are switched by the control circuit 43,
The non-energized state (when power is not supplied to the control circuit) is on the resistor 42 side.

The DC / DC converter 29 boosts (or lowers) the output from the solar cell panel 28 to 290V. This 290V is not limited to this voltage, and may be a voltage higher than the voltage (280V) double-voltage rectified by the rectifier circuit 19 and the capacitors 20 and 21 (voltage after subtracting the voltage drop by the diode 30).

By setting the voltage in this way, D
The DC output of the C / DC converter 29 is supplied to the inverter circuit 2
5 can be supplied. That is, it can be added to the DC output of the rectifying and smoothing circuit, and the DC / DC converter 29
Output, that is, when the output of the solar cell decreases, such as when the output of the solar cell is insufficient and the power voltage decreases, power is supplied from the AC power supply 15 and the inverter circuit 25 is always supplied with the necessary power. What is supplied.

Reference numeral 30 denotes a backflow prevention diode, which is used when the output of the solar cell panel 28 is reduced and when the compressor 1
When the power consumption of No. 4 increases and the output of the solar cell panel 28 becomes insufficient, the DC power due to the double voltage rectification is prevented from flowing back to the solar cell panel 28.

A current detector 44 detects the current value of the DC power generated by the solar cell panel 28. As a sensor for detecting this DC current, for example, DC C.I. If the one that detects the DC current from the change in the output voltage of T (using the Hall element) is used, the DC current can be obtained without lowering the output voltage of the solar cell panel 28 and without inserting the detection resistor. Can be detected.

The control circuit 43 switches the switching contact pieces 40 and 41 according to the value of the direct current detected by the current detector 44. The current detected by the current detector 44 has a predetermined value (for the maximum output of the solar cell panel 28 of about 600 [W],
A current value of about 100 [m] corresponding to an output of about 10 [W]
Although it is set to A], it is arbitrarily set according to the maximum output of the solar cell panel 28 and the power consumption of the compressor. ) In the above case, the DC power generated by the solar cell panel 28 is converted to DC.
Supply to the / DC converter 29 side.

When the current value detected by the current detector 44 is smaller than the predetermined value, the DC power generated by the solar cell panel 28 is supplied to the resistor 42 side. That is, the output of the solar cell panel 28 is short-circuited by the resistor 42. This resistance 4
2 is set to a value at which the output voltage of the solar cell panel 28 does not increase, and a resistance value such that the maximum output voltage falls within the range of 30 to 40 [V].

The control circuit 43 is the microprocessor 2
When the stop signal is given from, the switching contact pieces 40 and 41 are switched to the resistor 42 side. Incidentally, the switching contact pieces 40, 41
Is set to be on the resistor 42 side when the commercial AC power supply 15 is cut off, that is, when the outdoor unit is stopped.

Therefore, when the compressor 14 is stopped, the air conditioner is not used, and the amount of power generated by the solar cell panel 28 is small at night, the switching contact pieces 40, 41 are used.
Is on the side of the resistor 42.

FIG. 2 is a flow chart showing the main operation of the outdoor unit shown in FIG. In this figure, in step S1, it is confirmed whether or not power is being supplied to the outdoor unit from the commercial AC power supply 15. If there is no power, the process proceeds to step S2. In step S2, switching contact pieces 40, 41
Is set to the resistor 42 side. Incidentally, the switching contact pieces 40, 41
The position of is the position when power is not supplied to the outdoor unit.

When electric power is supplied, the routine proceeds to step S3, where the microprocessor 2 is initialized, and subsequently at step S4, the operation control of the outdoor unit is carried out. This operation control is control that changes the operation / stop of the compressor 14 and the operation capacity (frequency of the pseudo sine wave supplied to the compressor 14) based on the control signal from the indoor unit 1.

Then, the conditions of steps S5 and S6 are judged to judge whether or not the electric power generated by the solar cell panel 28 is used. First, in step S5, it is determined whether the compressor 14 is operating, and the compressor 1
When No. 4 is operating, the process further proceeds to step S6, and it is determined whether or not the generated current T of the solar cell panel 28 is smaller than a predetermined value.

Therefore, from the judgments in steps S5 and S6, when the compressor 14 is operating and at the same time the power generation current T of the solar cell panel 28 is equal to or more than a predetermined value, step S9 is performed.
To the DC / DC converter 29.
Switch to the side. That is, the solar cell panel 2
The DC power generated from 8 is boosted and added to the output power of the rectifying and smoothing circuit.

Further, when the compressor 14 is stopped and when the generated current of the solar cell panel 28 is smaller than a predetermined value, the process proceeds to step S7 and the switching contact pieces 40 and 41 are set to the resistor 42 side. That is, the solar cell panel 28
Is short-circuited via the resistor 42.

In the power supply device configured as described above, when the power generation current of the solar cell panel 28 is small, the stress of the solar cell is reduced without utilizing the power generation of the solar cell. Also D
The solar cell panel 2 is used for operating power of the C / DC converter 29.
When the output of 8 is used, the operation of the DC / DC converter 29 can be stopped when the generated power of the solar cell panel 28 is reduced and the operating power is insufficient (when the voltage cannot be boosted to 290 [V]).

When the compressor 14 is stopped, the output of the solar cell panel 28 can be short-circuited via the resistor 42. That is, the electric power generated by the solar cell panel 28 can be consumed by the resistor 42, and the stress of the solar cell due to no load (actual opening of the output end) can be eliminated.

Further, when AC power is not supplied from the commercial AC power supply 15 to the outdoor unit, the solar cell panel 2
The output of 8 can be shorted via resistor 42. That is, the potential of the power line connecting the rectifying / smoothing circuit of the outdoor unit and the inverter device or the power line connecting the inverter device and the compressor can be set to zero. Therefore, there is no place with a high voltage of 280 [V] inside the outdoor unit, and electric shock will not be caused even if an operator touches it by mistake during maintenance and inspection.

In the above embodiment, the supply of electric power to the outdoor unit is controlled by the contact pieces 1a and 1b of the indoor unit, and the microprocessor 2 is operated only when the electric power is supplied to the outdoor unit. However, the outdoor unit may be constantly supplied with power so that the microprocessor 2 is always in the operating state. At this time, a switch may be provided in the rectifying / smoothing circuit so that a high voltage of 280 [V] does not occur when the compressor is stopped.

FIG. 3 is a main part electric circuit diagram showing another embodiment of the present invention. In this figure, the difference from the electric circuit diagram shown in FIG. 1 is that the compressor uses a DC brushless motor, that the voltage of DC power supplied to the inverter device 25 is changed by the switching power supply 27, and that the rotation of the compressor 14 is changed. The corner is detected by the detector 50, and the stator winding to which the microprocessor 2 is energized is switched. The synchronous rotation speed of the DC brushless motor (the operating capacity of the compressor) changes according to the voltage applied to the stator winding. Therefore, the switching power supply 27 generates DC power for driving the microprocessor 2 and DC power of variable voltage, and the inverter device 25.
Supply to. This variable voltage is set by a signal from the microprocessor 2.

The detector 50 is the stator winding 3 of the compressor 14.
A signal is output to the microprocessor to determine the rotation angle of the rotor from the change in the induced voltage caused by the rotation of the rotor at 7, 38 and 39. The microprocessor 2 selects the stator winding to be energized based on this signal, and the inverter device 2 is selected so that the selected stator winding is energized.
ON / OFF of the switching element of No. 5 is obtained, and this switching signal is output to the inverter device 25 via the drive circuit 26. Therefore, the stator windings 37, 38, 3
9 is selected according to the rotation angle of the rotor and is energized.

[0049]

INDUSTRIAL APPLICABILITY The present invention is a power supply device for an air conditioner that drives a compressor using a solar cell and an AC power source, and when the generated current of the solar cell is larger than a predetermined value, the power generated by the solar cell is reduced. The output of the solar cell is short-circuited when the generated current of the solar cell is small and the voltage is boosted by the DC / DC converter and used as driving power for the compressor. Can be prevented.

When the compressor is not in operation or when the commercial AC power is not supplied to the outdoor unit, the output of the solar cell can be short-circuited to prevent a high voltage from being generated in the outdoor unit. It is possible to prevent the electric shock of the worker at the time of inspection.

[Brief description of drawings]

FIG. 1 is a main part electric circuit diagram of an air conditioner using an embodiment of the present invention.

FIG. 2 is a flowchart showing the main operation of the embodiment of the present invention.

FIG. 3 is an electric circuit diagram of a main part of an air conditioner showing another embodiment of the present invention.

[Explanation of symbols]

 14 Compressor 15 AC Power Supply 25 Inverter Circuit 28 Solar Cell Panel 29 DC / DC Converter 30 Diode 37 Stator Winding 38 Stator Winding 39 Stator Winding 40 Switching Contact 41 Switching Contact 42 Resistance 43 Control Circuit 44 Current Detector

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Kenichi Koga 2-18 Keihan Hondori, Moriguchi City, Osaka Prefecture Sanyo Electric Co., Ltd.

Claims (3)

[Claims] 1. A rectifying / smoothing circuit that rectifies and smoothes AC power supplied from an AC power supply into DC power and outputs the DC power, and a drive circuit that converts the DC power into AC power of an arbitrary frequency and supplies the AC power to a compressor. In a power supply device for an air conditioner having a solar cell, DC / DC for converting and outputting DC power generated by the solar cell to DC power having a voltage higher than the voltage of DC power obtained from the rectifying and smoothing circuit. (DC /
(DC) converter circuit, a current detection circuit that detects a generated current of the solar cell, and DC power output from the converter circuit when the generated current detected by the current detection circuit is larger than a predetermined value. In addition to the DC power output from the solar cell, a control circuit that cuts off the DC power output from the converter circuit and short-circuits the output of the solar cell when the generated current is smaller than the predetermined value is provided. The power supply for the air conditioner. 2. A rectifying / smoothing circuit that rectifies and smoothes AC power supplied from an AC power source into DC power, and outputs the DC power to each stator winding of the electric compressor. In a power supply device for an air conditioner having a drive circuit for supplying in a predetermined order based on, a solar cell and the DC power generated by this solar cell is higher than the voltage of the DC power obtained from the rectifying and smoothing circuit. A DC / DC (direct current / direct current) converter circuit for converting the voltage into direct current power for output, a current detection circuit for detecting the power generation current of the solar cell, and a power generation current detected by the current detection circuit is larger than a predetermined value. At this time, the DC power output from the converter circuit is added to the DC power output from the rectifying / smoothing circuit, and when the generated current is smaller than the predetermined value, the converter circuit outputs the DC power. And a control circuit that cuts off the direct current power and short-circuits the output of the solar cell. 3. The control circuit comprises a safety control circuit for stopping the output of the DC power of the converter circuit and short-circuiting the output of the solar cell even when the operation of the air conditioner is stopped. Alternatively, the power supply device for the air conditioner according to claim 2.