JPH09312928A - Open-phase detector of air-conditioner - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an open-phase detector which detects the open-phase of an air-conditioner securely and which is small in size and low in cost. SOLUTION: Resistors 2a, 2b and 2c and the input sides of phototransistor couplers 3a, 3b and 3c are respectively connected in series to each other between the respective phases of a 3-phase AC power supply 1. Diodes 4a, 4b and 4c are connected in parallel to the input sides of the phototransistor couplers 3a, 3b and 3c respectively so as to have their polarities opposite to the polarities of input sides of the phototransistor couplers 3a, 3b and 3c. Further, a transmitting means 5 through which the respective output signals of the phototransistor couplers 3a, 3b and 3c and a 3-input AND device 6 are connected and the potential level of the output signal of the 3-input AND device 6 is judged by a microcomputer control unit 7 to decide whether there is an open-phase or not.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an open-phase detector for an air conditioner that reliably detects open-phase input of a three-phase AC power supply for an air-conditioner powered by a three-phase AC power supply.

[0002]

2. Description of the Related Art In recent years, in an air conditioner using a three-phase AC power source of this kind as a power source, in the event of a phase loss due to a disconnection of the power source or disconnection of the connection, the purpose is to protect the equipment. It is required to have a small-sized and inexpensive means for detecting a missing phase.

Conventionally, the phase loss detecting device for an air conditioner of this type has generally been constructed as shown in Japanese Patent Laid-Open No. 6-263596. The configuration will be described below with reference to FIGS.

As shown in the figure, the phases of the three-phase AC power supply 1 (R-phase, S-phase, T-phase) (RS-phase, S-T phase, TR-phase) are RS-phase. Connected in series with the input side of a first resistor 2a having a resistance value R and a first phototransistor coupler 3a as a first current detector for detecting a current i _a flowing in the first resistor 2a. Then, the first diode 4a is connected in parallel so that the polarity on the input side of the first phototransistor coupler 3a is opposite to that of the first phototransistor coupler 3a, and the resistance value R is similarly set between the ST phases of the three-phase AC power supply 1. The second resistor 2b that it has and the current i flowing through this second resistor 2b
_It is connected in series with the input side of the second phototransistor coupler 3b as a second current detector for detecting _b, and the second phototransistor coupler 3b is connected so as to have a polarity opposite to that of the input side of the second phototransistor coupler 3b. Diode 4b of is connected in parallel,
Further, as a third current detector for detecting a third resistor 2c having a resistance value R similarly between the TR phases of the three-phase AC power supply 1 and a current i _c flowing through the third resistor 2c. Is connected in series with the input side of the third phototransistor coupler 3c, and the third diode 4c is connected in parallel so that the polarity is opposite to the polarity of the input side of the third phototransistor coupler 3c. , Transmission means 5 for transmitting the first, second and third output signals respectively output from the second and third phototransistor couplers 3a, 3b and 3c.
Then, the microcomputer controller 7 for detecting the phase loss based on the first, second and third output signals sent from the transmission means 5 is provided.

In the above arrangement, the first, second and third phototransistor couplers 3a, 3b and 3c for detecting the currents i _a , i _b and i _c are respectively output. The waveforms of the output signals v _a , v _b , and v _c are as shown in FIG. 10 when the respective phases of the three-phase AC power supply 1 are normally connected.
Becomes a pulse signal like this, and this first, second and third
The output signal v _a, v _b, v _c of the delay time t _a, determines t _b, t _c, in advance microcomputer control unit 7 1/3 hours of power supply frequency of the stored three-phase AC power supply 1 are ( If it is 50 Hz, 6.
Since it is the same as 7 ms and 60 Hz compared with 5.6 ms), it was judged that the phase was not missing. If one of the three phases of the three-phase AC power supply 1 is open phase (here, S phase is missing), there is generally some impedance Z between the two phases of the three-phase AC power supply 1. The load 8 is connected, and the currents i _a , i _b , and _ic have different phases, and the current i _z flowing through the load 8 is delayed by 60 degrees with respect to the voltage of the three-phase AC power supply 1. If the signals flow in phase, the waveforms of the first, second and third output signals v _a , v _b , v _c become pulse signals as shown in FIG. 11, and the three-phase signals stored in advance in the microcomputer control unit 7 are used. It was judged to be a phase loss because it was not the same compared with 1/3 time of the power supply frequency of the AC power supply 1 (6.7 ms for 50 Hz, 5.6 ms for 60 Hz).

Further, Japanese Patent Laid-Open No. 4-138384 proposes a three-phase detecting device which uses three input transformers corresponding to each phase voltage and judges a phase loss from the phase difference and the voltage value level. It was

[0007]

In such a conventional open-phase detecting device for an air conditioner, in the former case, the microcomputer controller controls the phase difference between the three pulse signals in a time-dependent manner, thereby controlling the time when the microcomputer is scarce. Since the capacity is burdened, there is a problem that a high-performance microcomputer control unit having a high time management capacity must be used, resulting in high cost.

In the latter case, three input transformers must be provided, which causes a problem that the device becomes large.

SUMMARY OF THE INVENTION The first object of the present invention is to solve the above problems and to reduce the size of the device and reduce the load on the time management capability of the microcomputer controller.

A second object is to reduce the size of the device, reduce the load on the time management capability of the microcomputer, and improve the external noise resistance of the device.

A third object is to promptly detect a missing phase. A fourth object is to reduce the size of the device, reduce the load on the time management capability of the microcomputer, and add control using a part of the device.

[0012]

SUMMARY OF THE INVENTION In order to achieve the above object, an open-phase detecting device for an air conditioner according to the present invention has first, second and third resistors for each phase of a three-phase AC power supply. And first,
Connecting the second and third current detectors in series,
First, second and third output signals respectively output when the respective currents flowing through the first, second and third resistors are detected by the first, second and third current detectors. Is connected to a logical product element which is a logical operation element having the first, second and third output signals transmitted by the transmitting means as input signals, and the output signal of the logical product element is connected. It is configured to include a microcomputer control unit for inputting.

According to the present invention, the first, second and third output signals sent from the transmission means are input to the logical product element which is a logical operation element, and the output signal of the logical product element is controlled by the microcomputer. Since it is input to the part, the microcomputer control unit can determine the open phase by the potential level, which is the basic capability,
It is possible to provide an inexpensive phase-reduction phase detector for an air conditioner that is capable of sufficiently detecting phase loss even with a sub-function type of a microcomputer.

Further, as another means, a first resistor and a first current detector are connected in series between arbitrary phases of a three-phase AC power source, and a current flowing through the first resistor is applied to the first resistor. A first transmission means for transmitting a first output signal that is output when detected by the current detector, and a second resistor between phases in which a phase of 120 degrees is delayed with respect to an arbitrary phase of the three-phase AC power supply. And a first switch that opens and closes according to a first output signal sent by the first transmission means and a second current detector are connected in series, and a current flowing through the second resistor is connected to the second switch. A second transmission means for transmitting a second output signal output when detected by the second current detector, the third resistor and the second transmission during the remaining phase of the three-phase AC power supply. A second switch and a third power switch which are opened and closed by the second output signal sent from the means. Connect the detector in series, the third
A third output means for transmitting a third output signal that is output when the current flowing through the resistor is detected by the third current detector, and the first, second and third output signals are provided. Is connected to a logical product element that is a logical operation element whose input signal is
It is configured to include a microcomputer control unit for inputting the output signal of the AND element.

According to the present invention, a switch that opens and closes by a signal having a 120-degree fast phase is provided between the two phases of the three-phase AC power source, so that the Hi level of the output signal of the logical product element during the phase loss is sufficiently long. It is possible to provide an open-phase detection device for an air conditioner that can determine the potential level without the waveform of the output signal of the AND element being formed by an integrating circuit using a capacitor or the like inserted as a noise countermeasure.

The other means is provided with a display device for displaying the fact that the phase is lost according to the information from the microcomputer control unit for detecting the phase loss.

According to the present invention, it is possible to provide an open phase detecting device for an air conditioner, which can clearly indicate that the open phase is present on the display device.

Another means is provided with a microcomputer control section capable of judging the time interval of a pulse signal for inputting a signal between any one phase that reports that a current has flowed between the phases.

According to the present invention, since any one-phase transmission means is connected to the microcomputer controller, it is possible to provide an open-phase detecting device for an air conditioner which can also determine the power supply frequency of a three-phase AC power supply.

[0020]

BEST MODE FOR CARRYING OUT THE INVENTION According to the present invention, first, second and third resistors and first, second and third current detectors are connected in series for each phase of a three-phase AC power supply. , The first,
Transmission for transmitting first, second and third output signals respectively outputted when the respective currents flowing in the second and third resistors are detected by the first, second and third current detectors Means and a microcomputer which is connected to a logical product element which is a logical operation element whose input signals are the first, second and third output signals transmitted by the transmitting means, and which inputs the output signal of the logical product element. It has a control unit,
The microcomputer control unit, which is compact in size and detects a phase loss, has an effect of being able to detect a phase loss by determining the potential level of the input signal.

Further, the first resistor and the first current detector are connected in series between arbitrary phases of the three-phase AC power supply, and the current flowing through the first resistor is detected by the first current detector. It is provided with a first transmission means for transmitting a first output signal that is output when it is detected, and 1 is provided for an arbitrary phase of the three-phase AC power supply.
A second resistor, a first switch that is opened and closed by a first output signal sent by the first transmission means, and a second current detector are connected in series during a phase delay of 20 degrees.
A second transmission means for transmitting a second output signal output when the current flowing through the second resistor is detected by the second current detector, and the remaining phase of the three-phase AC power supply A third resistor and a second switch which opens and closes by a second output signal sent from the second transmission means and a third
And a third transmission means for transmitting a third output signal that is output when the current flowing through the third resistor is detected by the third current detector. A microcomputer control unit that is connected to a logical product element that is a logical operation element that receives the first, second, and third output signals as input signals, and that inputs the output signal of the logical product element, In addition to the above-mentioned effects, it has an effect of improving resistance to external noise.

In addition to the above-mentioned first and second means, the provision of a display device for displaying the fact that the phase is lost according to the information from the microcomputer control section for detecting the phase loss causes the phase loss in addition to the above-mentioned operation. You can display that.

In addition to the first and second means, a microcomputer control unit capable of determining the time interval of the pulse signal for inputting a signal between any one phase that reports that a current has flowed between the phases is provided. In addition to the above functions, it can also be used in a power supply frequency detection circuit.

Embodiments of the present invention will be described below with reference to the drawings. The same reference numerals as those used in the conventional example indicate the same items, and detailed description thereof will be omitted.

[0025]

【Example】

(Example 1) As shown in FIG. 1, R- of the three-phase AC power source 1
The first resistor 2a and the input side of the first phototransistor coupler 3a are connected in series between the S phases, and the first diode so that the polarity is opposite to the polarity of the input side of the first phototransistor coupler 3a. 4a are connected in parallel. Similarly, S-
The second resistor 2b and the input side of the second phototransistor coupler 3b are connected in series between the T phases, and the second diode is connected so that the polarity is opposite to the polarity of the input side of the second phototransistor coupler 3b. 4b are connected in parallel. Further T-
Similarly, between the R phases, the third resistor 2c and the input side of the third phototransistor coupler 3c are connected in series so that the polarity is opposite to that of the input side of the third phototransistor coupler 3c. The diode 4c of 3 is connected in parallel. Then, the first, second and third phototransistor couplers 3a, 3b, 3c respectively output the first, second
And a transmission means 5 for transmitting the third output signal and a 3-input AND element as a logical product element of the logical operation elements for inputting the first, second and third output signals sent from the transmission means 5. 6 is connected, and the output signal of the 3-input AND element 6 is input to the microcomputer control section 7 to determine whether or not there is a phase loss.

In the above configuration, the waveforms of the currents i _a , i _b , i _c and the first, second and third output signals v _a , v _b , v _c and the output signal v _i of the 3-input AND element 6 are: If each phase of the three-phase AC power supply 1 is normally connected, the output signal v _i becomes constant at the ground potential (0 V) as shown in FIG. 2, and if the microcomputer controller 7 has the ground potential (0 V) in advance. It is stored so as to determine that it is not a phase loss, and as a result, it is determined that it is not a phase loss. If one of the three phases of the three-phase AC power supply 1 is open (here, S phase is missing), the load 8 is generally connected between the two phases of the three-phase AC power supply 1. The currents i _a , i _b , and _ic have different phases, and the current i _z flowing through the load 8
Is flowing in a phase delayed by 60 degrees with respect to the R-S phase voltage of the three-phase AC power supply 1, the first, second and third output signals v _a , v _b , v _c and the output of the 3-input AND element 6 are output. Signal v _i
3 has a waveform as shown in FIG. 3, and in particular, the waveform of the output signal v _i of the 3-input AND element 6 has a voltage (Hi level) higher than the ground potential (0V), and the microcomputer control unit 7 is previously provided with the ground potential (0V). If it is not), it is stored so as to judge that it is an open phase, and as a result, it is judged that it is an open phase.

As described above, according to the open-phase detecting device for the air conditioner of the first embodiment of the present invention, the microcomputer control section 7 can determine the open-phase detection by the determination based on the potential level of the input signal.

(Embodiment 2) As shown in FIG. 4, the first resistor 2a and the input side of the first phototransistor coupler 3a are connected in series between the R-S phases of the three-phase AC power supply 1. The first diode 4a is connected in parallel so that the polarity on the input side of the first phototransistor coupler 3a is opposite. On the other hand, between the S and T phases, one of the second resistors 2b is connected to the S phase, and the other of the second resistors 2b is the thyristor which is the output side of the first photothyristor coupler 9a as the first switch. Is connected to the cathode of the thyristor of the first photothyristor coupler 9a and the anode of the diode on the input side of the second phototransistor coupler 3b to connect the cathode of the diode of the second phototransistor coupler 3b. Connect to the T phase, this second
And the anode of the second diode 4b is connected to the cathode of the diode of the phototransistor coupler 3b and the anode of the thyristor of the first photothyristor coupler 9a.
The cathode of the diode 4b is connected. Furthermore, T-
Similarly, between the R phases, the third resistor 2c, the second photothyristor coupler 9b as the second switch, and the input side of the third phototransistor coupler 3c are connected in series,
The third diode 4c is connected in parallel so that the polarities of the input side of the third phototransistor coupler 3c and the output side of the second photothyristor coupler 9b are opposite to each other. And the first phototransistor coupler 3a
The first transmission means 5a for transmitting the first output signal of the first photo-thyristor coupler 9a is connected to the first driving means 10a for driving the first photo-thyristor coupler 9a connected to the input part of the first photo-thyristor coupler 9a. Then, the second transmission means 5b for transmitting the second output signal of the second phototransistor coupler 3b is connected to the second driving means 10b of the second photothyristor coupler 9b, and the third phototransistor coupler 3b is connected. The third transmission means 5c for transmitting the third output signal of the transistor coupler 3c, and the first, second and third output signals v sent from the first transmission means 5a and the second transmission means 5b. _a, v _b, v _c connects the three-input aND element 6 for inputting inputs an output signal of the 3-input aND element 6 to the microcomputer control unit 7, is to determine whether phase failure.

In the above structure, the current i_a, I_b, I_cWhen
First, second and third output signals v_a, V_b, V_cand
Output signal v of 3-input AND element 6_iThe waveform of the three-phase AC
When the three phases of the power supply 1 are connected normally, as shown in Fig. 5.
And the output signal v of the 3-input AND element 6_iIs the ground potential
(0V) becomes constant and the microcomputer control unit 7
If is the ground potential (0V), it is determined that the phase is not missing.
As a result, and as a result, it is not a phase loss
to decide. If one of the phases of the three-phase AC power supply 1 is open
(If S phase is missing here)
Impedance Z between two phases of the three-phase AC power supply 1
Be sure to connect the load 8 you have with the current i _a, I_b, I_c
Will flow, and the current i flowing through the load 8 will be_zThree
Phase delayed by 60 degrees with respect to the R-S phase voltage of the AC power supply 1.
If it flows, the first, second and third output signals
v_a, V_b, V_cAnd the output signal v of the 3-input AND element 6_i
The waveform of is as shown in Fig. 6, especially for the 3-input AND element 6.
Output signal v_iWaveform is higher than ground potential (0V).
Pressure (Hi level), and the microcomputer control unit 7
If it is not the ground potential (0V), memorize it so as to judge it as an open phase
As a result, it is determined that the phase is missing.

As described above, according to the open phase detecting apparatus for the air conditioner of the second embodiment of the present invention, the microcomputer control section 7 can judge the open phase detection by the judgment based on the potential level of the input signal. Compared with the first embodiment, the high level of the output signal v _i of the logical product element continues for a long time, and even if an integrating circuit using a capacitor or the like is generally inserted into the microcomputer input section as a noise countermeasure, the logical product element The output signal v _i does not become dull, and the threshold voltage of the microcomputer control unit 7 can be sufficiently exceeded.

(Embodiment 3) As shown in FIG. 7, 3 inputs A
An LED 11 is provided as a display device for displaying an abnormality of the open phase in the microcomputer control unit 7 which detects the open phase based on the output signal v _i of the ND element 6.

In the above structure, when the microcomputer control section 7 detects a phase loss, the output signal output in response to this is L level.
By transmitting to the ED 11, the LED emits light to visually indicate that the phase is lost.

As described above, according to the open-phase detecting device for the air conditioner of the third embodiment of the present invention, the display device clearly displays the open-phase condition, which facilitates the determination.

(Embodiment 4) As shown in FIG. 8, the microcomputer control unit 7 inputs the output signal v _a transmitted from the transmission means 5a and judges the power supply frequency of the three-phase AC power supply 1. is there.

In the above configuration, the microcomputer controller 7 determines the pulse interval time of the output signal v _a to be 20 ms.
If so, the power supply frequency of the three-phase AC power supply 1 is 50 Hz, 1
If it is 6.7 ms, it can be determined as 60 Hz.

As described above, according to the open phase detecting device for the air conditioner of the fourth embodiment of the present invention, the power supply frequency of the three-phase AC power supply can be easily determined by using a part of the open phase detecting device. You can

[0037]

As is apparent from the above embodiments, according to the present invention, the first, second and third output signals sent from the transmission means are input to the logical product element which is the logical operation element. , Since the output signal of this logical product element is input to the microcomputer control unit, the microcomputer control unit can determine the phase loss by the potential level which is the basic capability, and the microcomputer low-level function type also performs sufficient phase loss detection. It is possible to provide a low-cost and miniaturized phase loss detection device for an air conditioner.

In addition to the above, since a switch that opens and closes by a signal with a 120 ° early phase is provided between the two phases of the three-phase AC power supply, the output signal Hi of the AND element at the time of phase loss is Hi.
It is possible to provide an open-phase detection device for an air conditioner that outputs a sufficiently long time and can determine the potential level without the waveform of the output signal of the AND device being formed by an integrating circuit using a capacitor or the like inserted as a noise countermeasure. .

Further, it is possible to provide an open phase detecting device for an air conditioner, which can clearly indicate the open phase by the display device.

Further, since the transmission means for any one phase is connected to the microcomputer controller, it is possible to provide the open phase detecting device for the air conditioner which can judge the power supply frequency of the three-phase AC power supply.

[Brief description of drawings]

FIG. 1 is an electric circuit diagram showing a configuration of an open-phase detector for an air conditioner according to a first embodiment of the present invention.

FIG. 2 is a waveform diagram of each signal for explaining the operation when the three-phase AC power supply according to the first embodiment is normally connected.

FIG. 3 is a waveform diagram of each signal for explaining the operation when one phase of the three-phase AC power supply according to the first embodiment is open.

FIG. 4 is an electric circuit diagram showing the configuration of an open-phase detector for an air conditioner according to a second embodiment of the present invention.

FIG. 5 is a waveform diagram of each signal for explaining the operation when the three-phase AC power supply of the second embodiment is normally connected.

FIG. 6 is a waveform diagram of each signal for explaining the operation when one phase of the three-phase AC power supply according to the second embodiment is open.

FIG. 7 is a block diagram showing the configuration of an open-phase detector for an air conditioner according to the third embodiment.

FIG. 8 is an electric circuit diagram showing the configuration of an open-phase detector for an air conditioner according to the fourth embodiment.

FIG. 9 is an electric circuit diagram showing a configuration of a conventional open-phase detector for an air conditioner.

FIG. 10 is a waveform diagram of each signal for explaining the operation when the conventional three-phase AC power supply is normally connected.

FIG. 11 is a waveform diagram of each signal for explaining the operation when one phase of the conventional three-phase AC power supply is open phase.

[Explanation of symbols]

 1 Three-Phase AC Power Supply 2a First Resistor 2b Second Resistor 2c Third Resistor 3a First Phototransistor Coupler 3b Second Phototransistor Coupler 3c Third Phototransistor Coupler 5 Transmission Means 5a First Transmission means 5b Second transmission means 5c Third transmission means 6 3 Input AND element 7 Microcomputer control section 9a First photothyristor coupler 9b Second photothyristor coupler 9c Third photothyristor coupler 11 LED (display device) )

Claims (4)

[Claims] 1. A first, a second, and a third resistor and a first, a second, and a third current detector are connected in series for each phase of a three-phase AC power supply, and the first, the second, and the third current detectors are connected in series. Transmission means for transmitting first, second and third output signals respectively output when the respective currents flowing through the second and third resistors are detected by the first, second and third current detectors. And a microcomputer control for connecting to the logical product element which is a logical operation element having the first, second and third output signals transmitted by the transmission means as input signals and inputting the output signal of the logical product element. Phase detector for air conditioner equipped with a section. 2. A first resistor and a first current detector are connected in series between arbitrary phases of a three-phase AC power supply, and a current flowing through the first resistor is detected by the first current detector. A first transmission unit that transmits a first output signal that is output when detected is provided, and the second resistor and the first resistor are provided between phases in which the phase is delayed by 120 degrees with respect to an arbitrary phase of the three-phase AC power supply. First opening and closing by the first output signal sent by the transmission means of
And a second current detector connected in series to transmit a second output signal that is output when the current flowing through the second resistor is detected by the second current detector.
Second transmission means sent from the third resistor and the second transmission means during the remaining phase of the three-phase AC power supply.
A second switch that opens and closes in accordance with the output signal of 3rd and a third current detector are connected in series, and a third current is output when the current flowing through the third resistor is detected by the third current detector. Output signal of the logical product element connected to the logical product element which is a logical operation element having the first, second and third output signals as input signals. A phase loss detection device for an air conditioner equipped with a microcomputer control unit for inputting. 3. The open phase detecting device for an air conditioner according to claim 1, further comprising a display device for displaying the open phase based on information from a microcomputer control unit for detecting the open phase. 4. An arbitrary 1 that conveys that a current has flowed between the phases.
The phase loss detecting device for an air conditioner according to claim 1 or 2, further comprising a microcomputer control unit capable of determining a time interval of a pulse signal for inputting a signal between phases.