JP3522078B2 - Control device for air conditioner - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a control device for an air conditioner, which obtains power supplies for a DC motor and a microcomputer by a single power supply circuit (switching power supply).
More specifically, the present invention relates to a control device for an air conditioner that stabilizes a switching power supply circuit at the time of a momentary interruption (power failure) of a commercial AC power supply and prevents malfunction.

[0002]

2. Description of the Related Art In recent years, many air conditioners have adopted a switching power supply circuit as a power supply circuit in order to save energy, and have realized low loss and high efficiency.
For example, as shown in FIG. 3, the control device of the air conditioner includes a rectifier 2 that converts a commercial AC power supply 1 into a DC, a smoothing capacitor 3 that smoothes the converted DC voltage, and a smoothed DC power supply. Voltage V1 (= (Ns1 / Np) × V
in), V2 (= (Ns2 / Np) × Vin) and outputs the converted transformer circuit 4, diodes (rectifiers) Da, Db and capacitors Ca, Cb.
And a load using the voltage V2 as a power source (for example, a DC motor for indoor ventilation) 5
And a microcomputer 6 for driving and controlling the load 5 by using the voltage V1 as a power source.

Note that Vin is the input voltage of the switching transformer circuit 4, Np is the number of windings on the primary side of the transformer, and Ns.
1, Ns2 is the number of windings on the secondary side thereof, and the switching transformer circuit 4 shown in FIG. 3 is an example. Also, since the switching power supply circuit is already known, its operation description is omitted. Moreover, the said control apparatus is equipped with the apparatus required for the said air conditioner. Further, the load 5 includes a drive control circuit that drives the DC motor to rotate in a predetermined manner according to a control signal from the microcomputer 6, and the microcomputer 6 executes processing necessary for the air conditioner in response to a signal from the remote controller. .

As is apparent from FIG. 3, the load 5 and the microcomputer 6 are driven by one switching power supply.
In other words, since it is possible to obtain the power source of, that is, the power source for high power and the power source for low power are not required, not only energy saving but also downsizing and cost reduction of the air conditioner can be realized.

[0005]

By the way, in the control device of the air conditioner, since the output of the switching power supply has two systems and the air conditioner tends to be large, the load of the switching power supply is increased. It becomes large and it is necessary to employ a switching power supply having a capacity of several tens of W or more.

However, in the switching power supply, the output voltage is more difficult to stabilize as the load current change width (minimum current to maximum current width) increases, despite the feature of output stabilization. When the commercial AC power supply 1 is momentarily cut off (including a power failure), the larger the load current is, the lower the stability performance of the output voltage is, which causes the stop or malfunction of the device. In addition, such an operation stop or malfunction of the air conditioner causes the user to feel uncomfortable.

The present invention has been made in view of the above problems, and an object thereof is to control an air conditioner capable of preventing a malfunction due to a power failure when a load current is large so as not to make a user feel uncomfortable. To provide a device.

[0008]

[Means for Solving the Problems]
Because, the first invention was a rectifying means for converting a commercial AC power source into a DC voltage, a smoothing means for smoothing the direct current voltage, respectively receives the smoothed voltage to a predetermined voltage value
And a scan <br/> switching power supply having a switching transformer means for obtaining two power, output from the switching power supply
One of the power sources is driven to drive the load of the air conditioner.
While being used as a power source, the other power source drives the control means (microcomputer) of the air conditioner.
In the control device of the air conditioner used as a power source ,
The switching power supply between the rectifying means and the smoothing means
Detect and that current detecting means to detect an input interruption of the commercial AC power source at the input stage of the rectifying means an input current to
That a instantaneous disconnection detecting means, when the interruption of the quotient <br/> AC power source by said interruption detecting means is detected, the switching power
If the input current to the source is above a certain value,
The negative current should be reduced to reduce the load current, including stopping the load.
It is characterized in that the load is controlled and the instantaneous interruption of the commercial AC power source is notified.

[0009] In the first invention, the current detecting means composed of a resistor provided between the smoothing means and said rectifying means, a current detection circuit for detecting a potential difference across the resistor, the it is preferred that the microcomputer so as to detect the input current by a detection signal from the current detection circuit.

Further , in order to achieve the above-mentioned object,
Ming is a rectifying means for converting a commercial AC power supply into a DC voltage,
And smoothing means for smoothing the direct current voltage, the two power respectively receiving the smoothed voltage is a predetermined voltage value
A switching power supply having switching transformer means for obtaining the output power from the switching power supply.
One power source is used as the drive power source for the load of the air conditioner.
And the other power source is used as a drive power source for the control means (microcomputer) of the air conditioner .
In the control device of the air conditioner, the negative power supplied to the load from the one power supply of the switching power supplies.
Comprising a that current detecting means to detect the load current, and instantaneous interruption detection means at the input stage you detect an input interruption of the commercial AC power supply of said rectifying means, said commercial AC by the interruption detecting means Power supply
Is detected, the load current is above the specified value.
The load current is reduced, including stopping the load.
Control the load so that
The feature is that it is designed to notify the power interruption.

[0011] In the first aspect of the present invention, a resistor provided between said current detecting means and the negative <br/> load and the one of the power supply of the switching power supply, the potential difference across the resistor And a current detection circuit for detecting, wherein the microcomputer detects the signal detected by the current detection circuit.
It is preferable to detect the load current.

[0012]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described in detail below with reference to FIGS. Note that FIG.
The same parts as those in FIG. 3 are designated by the same reference numerals and duplicate description will be omitted. The air conditioner of the present invention contributes to the stabilization of the output of the switching power supply by limiting and controlling the load current when the input commercial AC power supply is momentarily cut off (power failure) when the load current is large, and eventually stops the operation or malfunctions. It is intended to prevent the above.

Therefore, as shown in FIG. 1, the control device for an air conditioner of the present invention includes an instantaneous interruption detection circuit 10 for detecting an instantaneous interruption (power failure) of a commercial AC power source 1, a rectifier 2 and a smoothing capacitor. 3 and the current detection circuit 12 for detecting the current (input current) of the switching power supply by the potential difference between both ends of the resistor 11 and the resistor 11, and the function of the microcomputer 6 shown in FIG. And a microcomputer 13 having a function of limiting and controlling the current of the same load (DC motor) 5 when the detected current is large when the detected input commercial AC power supply is momentarily cut off.

[0014] According to the control apparatus of the air conditioner of the configuration, the input port of the microcomputer 13 has an input detection signal according to interruption detection circuit 10 and the current detection circuit 1 2, microcomputer 13 is an air conditioner While operating the current detection circuit 1 while inputting the detection signal from the instantaneous interruption detection circuit 10 from the interrupt terminal INT.
The detection signal of 2 is input from the input port.

The interruption of the commercial AC power supply 1 is caused by the interruption terminal I.
Using NT, count the input signal per unit time,
Since there is a method of detecting a momentary interruption or a power failure based on this count value, this is used to detect. On the other hand, the input current of the switching power supply is detected by sampling the detection signal from the current detection circuit 1 2 at every predetermined time.

[0016] Then, upon detection of the interruption of the commercial AC power source 1, if the current of the switching power supply if equal to or larger than the predetermined value, in other words, when the current of the switching power supply has a larger load current above a predetermined value, and limiting the driving control of the load 5, reducing the load current (i.e. decreasing the rotational speed of the DC motor). In other words, since the input current of the switching power supply is proportional to the output current, the input current must be above the specified value.
Means that the load current is large.

As described above, since the load current is limited, that is, the load current is reduced when the commercial AC power supply 1 is momentarily cut off (power failure), malfunction of the air conditioner, particularly malfunction of the microcomputer 13, is prevented. can do.
In addition, if the commercial AC power supply 1 fails for a moment, the load current can be reduced to maintain the output voltage of the switching power supply until the commercial AC power supply 1 is restored (the output can be stabilized). As a result, the performance of the switching power supply can be prevented from deteriorating, and the performance of the air conditioner can be prevented from deteriorating. Further, as the hardware, only the current detection means of the instantaneous interruption detection circuit 10, the resistor 11 and the current detection circuit 12 is added, and the others are processed by software, so that the cost can be reduced.

Further, when the microcomputer 13 detects a momentary interruption of the commercial AC power source 1, the microcomputer 13 turns on a lamp provided in the indoor unit, for example, blinks a lamp that is turned on during operation. As a result, the user can be notified of a momentary interruption of the commercial AC power supply 1, so that there is no sense of discomfort.

FIG. 2 is a block diagram illustrating a modified embodiment of the present invention. In FIG. 2, the same parts as those in FIG. In FIG. 2, a control device for an air conditioner according to the present invention includes a resistor 14 and a resistor 1 connected in series to a power supply line of a load 5.
A current detection circuit 15 for detecting the current (output current; load current) of the switching power supply based on the potential difference between both ends of 4.
In addition to the function of the microcomputer 13 shown in FIG. 1, a current flowing through the load (output current of the switching power supply)
To limit the load current for overcurrent protection, and to limit the current of the same load (DC motor) 5 when the detected current is large at the time of momentary interruption (power failure) of the input commercial AC power supply. And a microcomputer 16 having.

In this modified embodiment, the same processing as in the previous embodiment is performed except that the load current (that is, the current that affects the output stabilization of the switching power supply) is directly detected. Therefore, the microcomputer 16, upon detection of an instantaneous interruption of the commercial AC power supply 1 (power failure), if current of the load 5 is sufficient that a predetermined value or more, and limiting the driving control of the DC motor of the load 5, i.e. Reduce the load current (lower the DC motor speed).

As described above, since the load current is directly detected and the load current is limited when the commercial AC power source 1 is momentarily cut off (power failure), that is, the load current is reduced, malfunction of the air conditioner, In particular, the malfunction of the microcomputer 13 can be prevented more accurately. In addition, when the commercial AC power supply 1 fails for a moment, the load current can be reduced to reliably maintain the output voltage of the switching power supply until the commercial AC power supply 1 is restored (the output voltage can be stabilized. As a result, it is possible to prevent the performance of the switching power supply from being deteriorated and prevent the performance of the air conditioner from being deteriorated.

Further, even if there is no momentary interruption (power failure) of the commercial AC power supply 1, when the load current reaches a predetermined value, drive control of the load is limited, that is, the load current can be lowered for the purpose of overcurrent protection. It is possible (the rotation speed of the DC motor can be lowered), and eventually the performance of the air conditioner can be prevented from deteriorating.

[0023]

As described above, according to the invention of the control device for an air conditioner, the power supply for the load and the power supply for the control means (microcomputer) of the air conditioner are controlled by the switching power supply. In the control device of the obtained air conditioner, a current detection unit for detecting an input current of the switching power supply and a momentary interruption detection unit for detecting an input interruption of a commercial AC power source are provided, and the commercial AC When the power supply is momentarily cut off, the current of at least the load is limited in accordance with the detected input current, or the load is stopped, and the instantaneous interruption is notified. Current can be limited, for example, when the load is a DC motor for indoor ventilation, when the rotation speed of the induction conductor is high (the load current is large When the commercial AC power supply is momentarily cut off, the rotational speed of the AC power supply is reduced, so that the burden on the switching power supply is reduced, that is, it is possible to suppress the adverse effect on the stabilization of the output voltage of the switching power supply. It is possible to prevent malfunctions and malfunctions of the microcomputer, and it is possible to prevent the user from feeling uncomfortable due to the notification of instantaneous interruption.

According to a second aspect of the present invention, the current detecting means in the first aspect comprises a resistor provided between the rectifying means and the smoothing means, and a current detecting circuit for detecting a potential difference between both ends of the resistor. Since the microcomputer detects the input current by the detection signal from the current detection circuit, in addition to the effect of claim 1, only a simple hardware circuit is added and the cost can be reduced. There is.

According to a third aspect of the present invention, in the control device for an air conditioner in which the power supply for the load and the power supply for the control means (microcomputer) of the air conditioner are obtained by the switching power supply, the output of the switching power supply is provided. The commercial AC power supply includes current detection means for detecting a current and instantaneous interruption detection means for detecting an input instantaneous interruption of the commercial AC power supply, while limiting the current of the load according to the detected output current. When a momentary interruption occurs, at least the current of the load is limited according to the detected output current, or the load is stopped, and the instantaneous interruption is notified, so that the load is a DC for indoor ventilation, for example. In the case of an electric motor, the current of the DC motor can be limited when the rotational speed of the induction motor is high (when the load current is large). By this, overcurrent protection can be performed, load current can be limited at the time of momentary interruption (power failure) as in claim 1, and more accurate current limitation can be performed because the load current is directly detected. That is, there is an effect that a bad influence on the stabilization of the output voltage of the switching power supply can be suppressed more accurately, and various malfunctions and malfunctions of the microcomputer can be surely prevented.

According to the invention described in claim 4, the current detecting means in claim 3 comprises a resistor provided between the switching power supply and the load, and a current detecting circuit for detecting a potential difference between both ends of the resistor. Since the microcomputer detects the input current by the detection signal from the current detection circuit, in addition to the effect of claim 3, there is an effect that only a simple hardware circuit is added and the cost is low. .

[Brief description of drawings]

FIG. 1 is a schematic block diagram of a control device for an air conditioner showing an embodiment of the present invention.

FIG. 2 is a schematic block diagram of a control device for an air conditioner showing a modified embodiment of the present invention.

FIG. 3 is a schematic block diagram of a control device for a conventional air conditioner.

[Explanation of symbols]

1 AC power supply 2 rectifier 3 smoothing capacitors 4 Switching transformer circuit 5 load (DC motor for indoor ventilation) 6,13,16 microcomputer (control means) 10 Instantaneous interruption detection circuit 11,14 resistor 12,15 Current detection circuit Ca, Cb capacitors Da, Db diode

─────────────────────────────────────────────────── ─── Continuation of the front page (56) Reference JP-A-6-313637 (JP, A) JP-A-1-231685 (JP, A) JP-A-6-30597 (JP, A) JP-A-5- 115198 (JP, A) JP 4-117127 (JP, A) JP 63-100286 (JP, A) Actual opening 61-197433 (JP, U) Actual opening 62-188986 (JP, U) (58) Fields surveyed (Int.Cl. ⁷ , DB name) F24F 11/02 102

Claims (4)

(57) [Claims] 1. A quotient AC power supply and rectifier means for converting the DC voltage, a smoothing means for smoothing the direct current voltage, said smoothing
Two which are respectively a predetermined voltage value by receiving a voltage
And a switching power supply having switching transformer means for obtaining the power supply of the switching power supply.
The one power source is the drive power source for the load of the air conditioner.
And the other power source is the drive power source for the control means (microcomputer) of the air conditioner.
In the control device of the air conditioner used as the switching power supply between the rectifying means and the smoothing means.
Detect and that current detecting means to detect an input interruption of the commercial AC power source at the input stage of the rectifying means an input current to
That a instantaneous disconnection detecting means, when the interruption of the quotient <br/> AC power source by said interruption detecting means is detected, the switching power
If the input current to the source is above a certain value,
The negative current should be reduced to reduce the load current, including stopping the load.
A control device for an air conditioner, which is configured to control a load and notify a momentary interruption of the commercial AC power supply . Wherein said current detecting means composed of a resistor provided between the <br/> smoothing means and said rectifying means, a current detection circuit for detecting a potential difference across the resistor, the micro The control device for an air conditioner according to claim 1, wherein the computer detects the input current based on a detection signal from the current detection circuit. Wherein the quotient AC power supply and rectifier means for converting the DC voltage, a smoothing means for smoothing the direct current voltage, said smoothing
Two which are respectively a predetermined voltage value by receiving a voltage
And a switching power supply having switching transformer means for obtaining the power supply of the switching power supply.
The one power source is the drive power source for the load of the air conditioner.
And the other power source is the drive power source for the control means (microcomputer) of the air conditioner.
In the control device of the air conditioner used as, from the one power supply of the switching power supply to the load
Includes a detection to that current detecting means the load current supplied, and - stop detecting means that detect <br/> the input stage side input interruption of the commercial AC power supply of said rectifying means, said interruption When the detecting means detects a momentary interruption of the commercial AC power source , the load current is detected.
If it is more than the fixed value,
While controlling the load to reduce the load current,
A control device for an air conditioner, which is configured to notify an instantaneous interruption of the commercial AC power supply . Wherein said current detecting means composed of a resistor provided between the load and the one of the power supply of the switching power supply, a current detecting circuit for detecting a potential difference across the resistor, the micro The control device for an air conditioner according to claim 3, wherein the computer detects the load current based on a detection signal from the current detection circuit.