JP3706445B2 - Air conditioner control device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an improvement of a control device for an air conditioner including a compressor having a crankcase heater.
[0002]
[Prior art]
In general, in an air conditioner equipped with a compressor having a crankcase heater, a state in which liquid refrigerant dissolved in refrigeration oil is separated and vaporized by energizing the crankcase heater while the compressor is stopped. Then, the compressor is operated. If the compressor is operated as it is without detecting that the crankcase heater is disconnected, liquid compression occurs, leading to troubles such as breakage of the compressor.
[0003]
As a conventional disconnection detection, an electromagnetic contactor is provided in a path for supplying electric power to the compressor, a crankcase heater is connected to the power supply side wiring as viewed from the electromagnetic contactor, and the compressor and the crankcase heater are connected. Provide a current transformer in the common wiring, determine whether the crankcase heater circuit is normal based on the secondary winding current of this current transformer, and operate the auxiliary relay when it is determined normal A technique for enabling the on-operation of an electromagnetic contactor has been proposed (Japanese Patent Laid-Open No. 5-180547).
[0004]
[Problems to be solved by the invention]
However, the conventional configuration is configured to determine whether the crankcase heater circuit is normal or not based on whether the current of the crankcase heater exceeds a predetermined threshold value. In order to detect a crankcase heater current whose current value is much smaller than the compressor current using the output of the current transformer that detects the current, there is a problem that the detection sensitivity is lowered.
[0005]
Further, in the conventional configuration, when it is determined that the crankcase heater circuit is normal, the auxiliary relay is operated so that the electromagnetic contactor can be turned on. Therefore, the auxiliary relay must be used. There is a problem of being.
[0006]
The present invention has been made to solve the above problems, and a first object is to detect whether the crankcase heater circuit is normal or not with a high sensitivity using a current transformer that detects a compressor current. An object of the present invention is to provide a control device for an air conditioner that can be used.
[0007]
A second object is to eliminate the need for an auxiliary relay that enables the electromagnetic contactor to be turned on under the condition that the crankcase heater circuit is normal, and to further simplify the configuration of the air conditioner. It is to provide a control device.
[0008]
[Means for Solving the Problems]
The control device for an air conditioner according to claim 1 has a single magnetic core as a current transformer for detecting current of a compressor having a crankcase heater and determining abnormality of the crankcase heater circuit. A conductor that supplies power to the compressor and a conductor that supplies power to the crankcase heater are respectively passed through or wound as a primary coil, and based on the current flowing in the secondary coil of this current transformer, the compressor Current detection and abnormality determination of the crankcase heater circuit are performed, for example, when the crank heater current is much smaller than the compressor current, the winding of the conductor that supplies power to the crankcase heater is wound. By increasing the number of times, the current induced in the secondary coil can be increased, and the abnormality determination sensitivity of the crankcase heater circuit can be increased.
[0009]
The control device for an air conditioner according to claim 2 has a single magnetic core as a current transformer for detecting current of a compressor having a crankcase heater and determining abnormality of the crankcase heater circuit. Using a conductor that supplies power to the compressor and a conductor that supplies power to the crankcase heater that is passed through or wound as a primary coil, the current flowing in the secondary coil of this current transformer is converted to an AC voltage. In addition, a first signal obtained by superimposing the AC voltage on a predetermined DC voltage, and a waveform shaping circuit that compares the first signal with a predetermined DC voltage and outputs a second signal having a rectangular waveform, Since the compressor current is detected based on the first signal and the abnormality of the crankcase heater circuit is determined based on the second signal, the voltage level suitable for the processing of the microcomputer is determined. In addition, when determining the abnormality of the crankcase heater, it can be determined by the presence or absence of a rectangular wave signal, so that the sensitivity of abnormality determination is higher than when using a preset threshold value. It can be further increased.
[0010]
The control device for an air conditioner according to claim 3 has a single magnetic core as a current transformer for current detection of a compressor having a crankcase heater and to determine abnormality of the crankcase heater circuit. A conductor that supplies power to the compressor and a conductor that supplies power to the crankcase heater are respectively passed through or wound as a primary coil, and based on the current flowing in the secondary coil of this current transformer, the compressor When detecting the current and determining the abnormality of the crankcase heater circuit, the conductor supplying power to the crankcase heater is wound as many times as the magnetomotive force approximating the compressor current is obtained. In this respect, the sensitivity of abnormality determination of the crankcase heater circuit is increased.
[0011]
In the control device for an air conditioner according to claim 4, the energization period to the compressor having the crankcase heater does not overlap the energization period to the crankcase heater, and the general configuration of the electromagnetic contactor As an example, the main contact is provided with an auxiliary contact, and the compressor is supplied with drive power via the main contact of the electromagnetic contactor. Since heating power is supplied to the crankcase heater through the reverse auxiliary contact, it is possible to confirm that the crankcase heater is normal and eliminate the need for an auxiliary relay for operating the compressor. As a result, the configuration can be further simplified together with the improvement of the sensitivity of abnormality determination of the crankcase heater circuit.
[0012]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, the present invention will be described in detail based on preferred embodiments shown in the drawings.
[0013]
FIG. 1 is a circuit diagram showing an embodiment of the present invention. In the figure, an electromagnetic switch 3 is connected to a path for supplying three-phase AC power from a three-phase AC power source 1 to a compressor 2. The three main contacts 52C of the electromagnetic switch 3 are connected to the R, S, and T phases of the three-phase AC circuit, and when the coil 52C is excited, these main contacts 52C are turned on, and the compressor 2 is turned on. Supply drive power.
[0014]
In general, the electromagnetic switch 3 includes an auxiliary contact 15 whose on / off operation is opposite to that of the main contact 52C. The crank heater 4 is connected between the R-phase and S-phase power lines via the auxiliary contact 15.
[0015]
On the other hand, a current transformer 10 is provided on the three-phase AC power source 1 side as viewed from the electromagnetic switch 3. The current transformer 10 has an annular magnetic core 11, through which an R-phase power line penetrates as a primary conductor 12, and a conductive wire connected to the crank heater 4 serves as a primary winding 13 multiple times. A secondary winding 14 for winding a current signal is wound. A current detection signal waveform shaping circuit 7 is connected to the secondary winding 14. The current detection signal waveform shaping circuit 7 converts a current flowing through the secondary winding 14 into a voltage and superimposes it on a DC voltage of a predetermined level, and a rectangular wave voltage signal Vo ′ synchronized with the AC voltage. Are added to different input ports of the microcomputer 5.
[0016]
A control power supply circuit 6 is connected between the R-phase and S-phase power supply lines, and the control power supply circuit 6 outputs a DC voltage for operating the microcomputer 5, the auxiliary relay 8, and the abnormality display lamp 9. . The coil 52 </ b> C of the electromagnetic switch 3 is connected between the R-phase and S-phase power lines via the normally open contact X of the auxiliary relay 8.
[0017]
FIG. 2 is a circuit diagram showing a detailed configuration of the current detection signal waveform shaping circuit 7 connected to the secondary winding 14 of the current transformer 10. Here, the current transformer 10 includes a primary conductor 12 that penetrates the annular magnetic core 11, and a primary winding 13 and a secondary winding 14 that are wound around the annular magnetic core 11. Among these, a capacitor C1 for noise removal is connected between the output terminals of the secondary winding 14, and further, a series connection circuit of resistors (hereinafter referred to simply as resistors) R1 and R2 is connected. . Further, a series connection circuit of resistors R3 and R4 and a series connection circuit of diodes D1 and D2 are connected between a DC voltage source of 5V and a ground point. In this case, the mutual junction point between the resistors R3 and R4 is connected to the junction point between the resistor R2 and the secondary winding 14, and the mutual junction point between the diodes D1 and D2 is connected to the mutual junction point between the resistors R1 and R2. ing.
[0018]
The junction point between the diodes D1 and D2 is connected to the input port P1 of the microcomputer 5 and to the non-inverting input terminal (+) of the comparator 16 which is an operational amplifier. Rf is a feedback resistor for giving hysteresis and ignoring the noise level as a dead zone. On the other hand, a variable resistor VR is connected between the DC voltage source and the ground, and its sliding terminal is connected to the inverting input terminal (-) of the comparator 16 and to one end of the capacitor C2. The other end of this capacitor C2 is grounded.
[0019]
The operation of the present embodiment configured as described above will be described below.
[0020]
While the operation of the air conditioner is stopped, the main contact 52C of the electromagnetic switch 3 is in the off state, and conversely, the auxiliary contact 15 is in the on state. Therefore, the crank heater 4 is applied with the line voltage of each of the R and S phase power lines, and the refrigerating machine oil is heated. In this case, the current of the crank heater 4 is several tenths or less as compared with the R-phase line current when the compressor 2 is operated. For this reason, a line derived from the R-phase power line and connected to the crank heater 4 is wound around the annular magnetic core 11 of the current transformer 10 several tens of times.
[0021]
During the shutdown of the air conditioner, the voltage generated at both ends of the secondary winding 14 is applied to the series connection circuit of the resistors R1 and R2, divided by the ratio of the resistance values of these resistors, and the both ends of the resistor R2 For example, an AC voltage of about 0.3 VP-P is generated. In this case, the capacitor C1 serves to remove noise.
[0022]
On the other hand, the control power supply circuit 6 connected to each of the R and S phase power supply lines generates a 5V DC voltage as a control power supply and applies it to the microcomputer 5 and also shapes the current detection signal waveform by a wiring not shown. Also supplied to the circuit 7. The DC voltage supplied to the current detection signal waveform shaping circuit 7 is divided by the resistors R3 and R4, and the AC voltage generated at both ends of the resistor R2 is added to the DC voltage generated at the mutual junction of these resistors. The pulsating voltage (hereinafter simply referred to as voltage) Vo is applied to the non-inverting input terminal of the comparator 16. Here, if resistors R3 and R4 having the same resistance value are used, as shown in FIG. 3, a voltage Vo obtained by superimposing an AC voltage of 0.3 Vp-P on a DC voltage of 2.5 V is obtained. It is done. Further, the DC power supply voltage 5V is divided by the variable resistor VR to create a DC voltage of 2.5V, and this is applied to the inverting input terminal of the comparator 16 as the reference voltage Vref. The capacitor C2 plays a role of stabilizing the reference voltage Vref.
[0023]
When the voltage at the inverting input terminal is low compared to the voltage at the non-inverting terminal of the comparator 16, the output from the comparator 16 is at H level. Conversely, when the voltage at the inverting input terminal is high, the output from the comparator 16 is at L level. It becomes. Therefore, if the voltage Vo shown in FIG. 3 is applied to the inverting input terminal of the comparator 16, a rectangular wave voltage Vo 'having a remarkably large amplitude is applied to the input port P2 of the microcomputer 5 as shown in FIG. . When the rectangular wave voltage Vo 'is applied to the input port P2, the microcomputer 5 determines that the crank heater 4 is operating normally and operates the auxiliary relay 8. Therefore, the contact X is turned on, and the R and S phase power line voltage is applied to the coil 52C of the electromagnetic switch 3 to excite it. As a result, the main contact 52C is turned on, the three-phase AC voltage is supplied to the compressor 2, and the operation is started.
[0024]
During the operation of the compressor 2, the AC voltage induced in the secondary winding 14 by the current of the primary conductor 12 is divided by the resistors R1 and R2, and an AC voltage of 5 Vp-P is generated at both ends of the resistor R2. A voltage Vo in which this AC voltage is superimposed on a DC voltage of 2.5 V is applied to the input port P1 of the microcomputer 5. That is, as shown in FIG. 4, a sinusoidal AC voltage that oscillates between the ground voltage 0 V and 5 V is applied to the input port P 1 of the microcomputer 5. The microcomputer 5 converts this voltage signal into, for example, a digital signal and compares it with a predetermined threshold value to determine whether or not an excessive current has flowed through the compressor 2. If it is determined that the error has occurred, the abnormality display lamp 9 is turned on to notify the operator.
[0025]
The diode D1 shown in FIG. 2 suppresses the peak voltage in the positive direction to 5V, the diode D2 suppresses the peak voltage in the negative direction to -5V, and the absolute value of the voltage applied to the input port P1 of the microcomputer 5 Is limiting.
[0026]
According to the above-described embodiment, the current detection of the compressor 2 having the crank heater 4 and the current transformer 10 for determining the circuit abnormality of the crankcase heater 4 are performed on the single annular magnetic core 11. Each of the secondary windings 14 of the current transformer 10 is formed by passing a primary conductor 12 that supplies power to the compressor as a primary coil and winding a conductor that supplies power to the crank heater 4 a plurality of times. Since the current detection of the compressor 2 and the abnormality of the crankcase heater 4 are discriminated based on the current flowing through the compressor, even if the crank heater current is much smaller than the compressor current, the crankcase heater 4 The sensitivity for discriminating a circuit abnormality can be increased.
[0027]
Further, the current flowing through the secondary winding 14 of the current transformer 10 is converted into an AC voltage, and a signal Vo in which the AC voltage is superimposed on a predetermined DC voltage, and the signal Vo are compared with a predetermined DC voltage. And a current detection signal waveform shaping circuit 7 for outputting a rectangular wave signal Vo ', detects the compressor current based on the signal Vo, and determines the circuit abnormality of the crankcase heater 4 based on the signal Vo'. Since it can be converted to a voltage level suitable for the processing of the microcomputer, it can be determined based on the presence or absence of a rectangular wave signal when determining whether the crankcase heater 4 is abnormal. Compared with the case where a threshold value is used, the sensitivity of discrimination can be further increased.
[0028]
Furthermore, since the conductor for supplying electric power to the crankcase heater 4 is wound several tens of times, the handling of the signal is facilitated, and the sensitivity of the abnormality determination of the circuit of the crankcase heater 4 is further enhanced. There is.
[0029]
Furthermore, driving power is supplied to the compressor 2 via the main contact 562C of the electromagnetic switch 3, and heating power is supplied to the crankcase heater 4 via the auxiliary contact 15 whose on / off state is opposite to that of the main contact 52C. Therefore, it is possible to confirm that the crankcase heater 4 is normal and to eliminate the need for an auxiliary relay for operating the compressor 2, thereby making it possible to determine abnormality of the crankcase heater circuit. Along with the improvement in sensitivity, the configuration can be further simplified.
[0030]
According to the above embodiment, the primary conductor 12 is passed through the annular magnetic core 11 in response to the fact that the current of the compressor 2 is much larger than the current of the crank heater 4. It is obvious that the annular core 11 may be wound an appropriate number of times according to the current value of the machine.
[0031]
【The invention's effect】
As is apparent from the above description, according to the control device for an air conditioner according to claim 1, the conductor for supplying power to the compressor and the conductor for supplying power to the crankcase heater are provided to the single magnetic core. Are used as the primary coils, so that the sensitivity for determining abnormality of the crankcase heater circuit can be increased even when the crank heater current is much smaller than the compressor current.
[0032]
According to the control device for an air conditioner according to claim 2, a conductor that supplies power to the compressor and a conductor that supplies power to the crankcase heater are passed through the single magnetic core as primary coils. A first signal in which the current flowing in the secondary coil of the current transformer is converted into an AC voltage and the AC voltage is superimposed on a predetermined DC voltage, and the first signal is used. Is provided with a waveform shaping circuit that outputs a second signal in the form of a rectangular wave by comparing with a predetermined DC voltage, detects the compressor current based on the first signal, and determines the crank based on the second signal. Since the abnormality of the case heater circuit is determined, it can be determined by the presence or absence of a rectangular wave signal having a voltage level suitable for microcomputer processing, compared with the case where a preset threshold value is used. , Abnormal It can be further enhanced another sensitivity.
[0033]
According to the control device for an air conditioner according to claim 3, in detecting the current of the compressor and determining the abnormality of the crankcase heater circuit, the conductor for supplying power to the crankcase heater has a magnetomotive force approximate to the compressor current. Since the current transformer wound as many times as possible is used, the handling of the signal is facilitated and the sensitivity of the abnormality determination of the crankcase heater circuit is increased.
[0034]
According to the control device for an air conditioner according to claim 4, the driving power is supplied to the compressor via the main contact of the electromagnetic contactor, the auxiliary is interlocked with the main contact, and the on / off state is reversed. Since the heating power is supplied to the crankcase heater through the contact, it is possible to confirm that the crankcase heater is normal and eliminate the need for an auxiliary relay for operating the compressor. The configuration can be further simplified together with the improvement of sensitivity for abnormality determination of the case heater circuit.
[Brief description of the drawings]
FIG. 1 is a circuit diagram showing a configuration of an embodiment of the present invention.
FIG. 2 is a circuit diagram showing a detailed configuration of main elements of the embodiment shown in FIG. 1;
FIG. 3 is a diagram showing the relationship between voltage and time in order to explain the operation of the embodiment shown in FIG. 1;
4 is a diagram showing the relationship between voltage and time in order to explain the operation of the embodiment shown in FIG. 1; FIG.
[Explanation of symbols]
2 Compressor 3 Electromagnetic switch 4 Crank heater 5 Microcomputer 6 Control power circuit 7 Current detection signal waveform shaping circuit 8 Auxiliary relay 9 Abnormal indicator lamp 10 Current transformer 11 Annular magnetic core 12 Primary conductor 13 Primary winding 14 Secondary Winding 15 Auxiliary contact 16 Comparator

Claims (4)

In an air conditioner equipped with a compressor having a crankcase heater,
A conductor that supplies power to the compressor and a conductor that supplies power to the crankcase heater are each wound as a primary coil around a single magnetic core, and a secondary coil is wound around the single magnetic core. Current transformer,
Current detection means for detecting the current of the compressor based on the current flowing in the secondary coil of the current transformer;
An air conditioner control device comprising: an abnormality determining means for determining an abnormality of the crankcase heater circuit based on a current flowing through a secondary coil of the current transformer. In an air conditioner equipped with a compressor having a crankcase heater,
A conductor that supplies power to the compressor and a conductor that supplies power to the crankcase heater are each wound as a primary coil around a single magnetic core, and a secondary coil is wound around the single magnetic core. Current transformer,
A current flowing through the secondary coil of the current transformer is converted into an AC voltage, a first signal in which the AC voltage is superimposed on a predetermined DC voltage, and the first signal is compared with a predetermined DC voltage. A waveform shaping circuit for outputting a rectangular-wave-like second signal;
Current detecting means for detecting a current of the compressor based on the first signal;
An air conditioner control apparatus comprising: an abnormality determination unit that determines an abnormality of the crankcase heater circuit based on the second signal. In an air conditioner equipped with a compressor having a crankcase heater,
A conductor that supplies power to the compressor passes through a single annular magnetic core as a primary coil, and a conductor that supplies power to the crankcase heater is used as a primary coil to obtain a magnetomotive force that approximates the compressor current. A current transformer wound around the single annular magnetic core, and a secondary coil wound around the single annular magnetic core;
Current detection means for detecting the current of the compressor based on the current flowing in the secondary coil of the current transformer;
An air conditioner control device comprising: an abnormality determining means for determining an abnormality of the crankcase heater circuit based on a current flowing through a secondary coil of the current transformer. In an air conditioner equipped with a compressor having a crankcase heater,
Drive power is supplied to the compressor via a main contact that is turned on by an operation command, and heating power is supplied to the crankcase heater via an auxiliary contact that is linked to the main contact and that is reverse in the on / off state. An electromagnetic contactor to supply,
A conductor that supplies power to the compressor and a conductor that supplies power to the crankcase heater are each wound as a primary coil around a single magnetic core, and a secondary coil is wound around the single magnetic core. Current transformer,
Current detection means for detecting the current of the compressor based on the current flowing in the secondary coil of the current transformer;
An air conditioner control device comprising: an abnormality determining means for determining an abnormality of the crankcase heater circuit based on a current flowing through a secondary coil of the current transformer.

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