JP3215302B2 - 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 an air conditioner provided with an inverter circuit for changing the frequency of a compressor of an outdoor unit so as to obtain an optimum capacity according to a load.

[0002]

2. Description of the Related Art An air conditioner which realizes a refrigeration cycle by sequentially operating a compressor, a condenser, a decompressor, an evaporator and the like has been known. Recent air conditioners have an inverter circuit that supplies AC drive power to the compressor,
The output frequency of the inverter circuit is controlled according to the load. As a result, the optimal operation performance of the air conditioner with respect to the load is obtained, and the comfort of air conditioning, the energy saving effect, and the like are improved.

In a conventional air conditioner, a DC voltage is obtained by rectifying an AC output voltage of a commercial power supply with a bridge rectifier circuit or the like and smoothing the rectified voltage with a smoothing capacitor. The voltage is converted and given to the compressor. In such an air conditioner, since a capacitor input type circuit is formed, the input current is
It flows only near the top of the rectified waveform of the input voltage.
For this reason, the power factor of the power supply is reduced and the harmonic current is increased, so that not only the power loss is increased but also the power supply line is adversely affected by the harmonic current.

In view of such circumstances, IEC (Internati
The Onal Electrotechnical Commission) has been regulating the harmonic current of power supplies since 1996. Therefore, it is necessary to take some measures against such regulations.

As a technique for suppressing the harmonic current, Japanese Patent Application Laid-Open Nos. Hei 4-26374 and Hei 5-68376 propose an air conditioner equipped with an active filter. The active filter has a switching element that interrupts the rectified voltage, and turns the switching element on and off appropriately in accordance with the input current waveform so that the charging current waveform of the smoothing capacitor approaches the input current waveform. Has become. With such an active filter, harmonic components of the power supply current are reduced,
And the power factor can be increased.

Next, an example of a conventional air conditioner having an active filter will be described.

In this air conditioner, as shown in FIG. 10, the output of an AC commercial power supply 71 is full-wave rectified by a bridge rectifier circuit 72, and the voltage passed through an active filter 73 is smoothed by a smoothing capacitor 74. DC voltage. This DC voltage is converted into an AC voltage of an arbitrary frequency by a power module (inverter circuit) 75 and supplied to a compressor 76 serving as a load.

The active filter 73 includes a choke coil 77, a high-speed recovery diode 78, and a power transistor 79.
The switching 9 controls the amount of input current to the smoothing capacitor 74. ON / OFF of the power transistor 79 is controlled by the switching waveform generated by the switching waveform generator 80. The switching waveform generator 80 generates the above-mentioned switching waveform based on the input current waveform and the input voltage waveform to the active filter 73.

The power transistor 79 operates so that the waveform of the charging current of the smoothing capacitor 74 approaches the input current waveform by the above switching waveform. Thereby, the harmonic component of the power supply current is reduced and the power factor is improved.

In the above-described air conditioner, since the input current waveform is operated so as to approach the input voltage waveform, the output voltage V _O from the active filter 73 is applied to the commercial power supply 71.
Is controlled so as to be higher than the effective value voltage. Therefore, the switching waveform generator 80 performs feedback control on the output voltage V _O so that the boosted value of the output voltage V _O from the effective value voltage is always constant. Specifically, a difference between the output voltage V _O obtained by the error amplifier 81 and the reference voltage from the reference power supply 82 is obtained, and a switching waveform is determined by the switching waveform generator 80 based on the difference.

The air conditioner has a circuit overheat protection function. The overheat protection function is performed by the active filter 73 detected by the thermistor 83 and the resistor 84.
Operate based on temperature. The error of the detected temperature with respect to the reference temperature based on the reference voltage from the reference power supply 85 is output by the error amplifier 86, and the temperature rise detection value detecting section 87 detects the temperature rise value based on the error. Then, the boost stop signal generating section 88 causes the active filter 73 to switch the power transistor 79 based on the temperature rise value.
When it is determined that the temperature has risen to a predetermined value or more, the switching waveform generator 80 stops outputting the switching waveform.

As a result, the power transistor 79 stops and the active filter 73 generates heat due to the loss of the power transistor 79 and the high-speed recovery diode 78.
Is prevented from being overheated abnormally.

The above-described air conditioner also has an overvoltage protection function and an overcurrent protection function. The overvoltage protection function is to stop the output of the switching waveform by the switching waveform generation unit 80 when the overvoltage detection unit 89 detects that the output voltage from the active filter 73 is overvoltage. The overcurrent protection function is
When the overcurrent detection section 90 detects that the input current to the active filter 73 is overcurrent, the switching waveform generation section 80 stops the output of the switching waveform.

In the above-described air conditioner, an inverter control waveform is output from the operating frequency setting circuit 91 to the power module 75 in accordance with operating conditions during operation.
Then, the power module 75 applies a drive voltage of the set operating frequency to the compressor 76 by chopping the output voltage from the active filter 73 based on the waveform.

In the power module 75, heat is generated due to the loss of each switching element, and the amount of heat generated is detected as a voltage drop of the thermistor 92. In particular,
The above heat value (temperature) is input to the error amplifier 94 as a voltage divided by the thermistor 92 and the resistor 93.
In the error amplifier 94, the reference voltage (the output of the reference power supply 95)
Is obtained, and the error is output to the operation stop signal generator 96. When detecting that the temperature is abnormally rising based on the error amount, the operation stop signal generation unit 96 gives an instruction to stop the operation to the operation frequency setting circuit 91.

Thus, when an abnormal temperature occurs in the power module 75, the operating frequency setting circuit 91 stops the chopping operation of the power module 75. In this way, each switching element in the power module 75 is protected from being damaged by overheating.

[0017]

As described above, the conventional air conditioner is provided with an overheat protection function for protecting each part of the active filter 73 from overheating. However, since the outdoor unit of the air conditioner is installed outdoors, it may become abnormally hot due to direct sunlight shining during a high summer temperature. In this case, the temperature detected by the thermistor 83 becomes higher than the temperature due to the self-heating of the active filter 73. For this reason, even when the self-heating of the active filter 73 is not excessive, the boost stop signal generator 88 may stop the active filter 73.

The air conditioner is provided with an overheat protection function for protecting each part of the power module 75 from overheating. However, when the temperature of the outdoor unit becomes abnormally high as described above, the thermistor is used. The temperature detected by 92 becomes higher than the temperature due to the self-heating of the power module 75. For this reason, even when the self-heating of the power module 75 is not excessive, the operation stop signal generator 96 may stop the power module 75.

In the above-described air conditioner, when the input voltage to the active filter 73 is low because the output of the commercial power supply 71 is unstable, the boosted value of the active filter 73 indicates the operation of the air conditioner. Becomes unstable with changes in load. For this reason, the voltage applied to the compressor 76 fluctuates, and it becomes difficult to maintain a normal operation state.

In the above-described air conditioner, the voltage applied to the compressor 76 is controlled by the power module 75 based on operating conditions during operation. However, since the value of the voltage output from the active filter 73 is constant regardless of the operating conditions, a voltage higher than required for the operating conditions may be applied to the compressor 76. In such a case, there is a problem that an extra loss occurs during the chopping operation of the power module 75, which leads to an increase in power consumption.

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide an air conditioner that can maintain a good operation state even when the temperature is abnormal or the voltage is unstable. The purpose is.

[0022]

According to a first aspect of the present invention, there is provided an air conditioner comprising: a rectifier for rectifying an AC voltage output from an AC power supply; A smoothing means for smoothing the voltage to be a DC voltage, an inverting means for converting the DC voltage from the smoothing means into an AC voltage having a variable voltage and frequency by applying chopping, and applying the AC voltage to the compressor; The input current is provided between the means and the smoothing means, and the amount of current flowing into the smoothing means by switching of the switching element is adjusted to shape the input current into a waveform having substantially the same phase as the input voltage and substantially a sine wave. an active filter, a temperature detecting means for detecting the temperature of the active filter, the Sui as a target value the output voltage of the active filter Controls the switching of quenching elements, in an air conditioner and a switching control means for the switching element is stopped when the temperature of the active filter is a predetermined value or more, the temperature detected by said temperature detecting means Correction means for correcting the target value accordingly.

In the air conditioner according to the first aspect, when the temperature of the active filter is detected by the temperature detecting means, the target value is corrected by the correcting means in accordance with the detected temperature. For example, when the temperature of the active filter increases, the correction is performed so that the target value decreases in accordance with the increase in the temperature. As a result, the output voltage of the active filter decreases and the amount of current flowing through the switching element decreases. As a result, the self-heating of the active filter is suppressed, and the temperature detected by the temperature detecting means decreases.

[0024] Thus, the active, such as by the temperature of the active filter, the outside air temperature is abnormally high
Even if the temperature becomes higher than the temperature due to the self-heating of the filter, the frequency at which the switching elements are stopped by the switching control means can be greatly reduced.

An air conditioner according to a second aspect of the present invention is the first air conditioner, further comprising a maximum frequency defining means for defining a maximum value of the frequency in accordance with an output voltage of the active filter. I have.

For this reason, when the output voltage of the active filter decreases due to the decrease in the target value as described above, the maximum value of the frequency is set by the maximum frequency defining means accordingly. For example, when the output voltage of the active filter decreases, the correction is performed so that the maximum value of the frequency decreases in accordance with the decrease. As a result, the maximum driving capability of the compressor by the inverting means, that is, the maximum operating capability of the air conditioner is reduced, so that even if the output voltage of the active filter is reduced, the compressor can be driven with the corresponding capability. .

According to a third aspect of the present invention, there is provided an air conditioner for rectifying an AC voltage output from an AC power supply, and converting the rectified AC voltage to a DC voltage. Smoothing means for smoothing, a DC voltage from the smoothing means is chopped, and a voltage and a frequency are converted into an AC voltage having a variable voltage and applied to the compressor. Power control means for setting the frequency in accordance with the driving capability to be provided; and a power control means provided between the rectification means and the smoothing means for controlling an amount of current flowing into the smoothing means by switching of a switching element, thereby providing an input. An active filter for shaping the current into a waveform having substantially the same phase as the input voltage and a substantially sine wave, and the output voltage of the active filter serving as a target value And switching control means for controlling the urchin switching of the switching element, and according to the frequency set by the power control means is characterized by comprising a correction means for correcting the target value.

In the air conditioner according to the third aspect , the correction value corrects the target value according to the frequency set by the power control means. Thus, the output voltage of the active filter is controlled in accordance with the driving capability of the compressor (operating capability of the air conditioner) by the inverse converter. Therefore, the output voltage of the active filter does not become higher than required by the inverter, and the loss in the chopping operation of the inverter can be reduced.

[0029]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS First Embodiment The following will describe a first embodiment of the present invention with reference to FIGS.

Air conditioner (outdoor unit) according to the present embodiment
1 includes a bridge rectifier circuit 2, a smoothing capacitor 3, a power module 4, and an active filter 5 as a power supply system, as shown in FIG. In addition, the present air conditioner includes an inverter control unit and an active filter control unit as a control system.

The power supply system generates a DC voltage by rectifying an AC voltage from the commercial power supply 1 with a bridge rectifier circuit 2 and further smoothing it with a smoothing capacitor 3. The power supply system generates a three-phase AC voltage by the power module 4 based on the DC voltage and supplies the generated AC voltage to the compressor 6.

Power module 4 as inverse conversion means
Has six transistors 11 to 16 and six diodes 21 to 26. Transistors 11 and 12,
Transistors 13 and 14 and transistors 15 and 16
Are connected in series between two power supply lines. On the other hand, the diodes 21 to 26
To 16 individually connected in parallel. The power module 4 as an inverting means outputs three-phase AC voltages by switching the transistors 11 to 16 based on an inverter control waveform from an operation frequency setting circuit 42 described later.

The compressor 6 is connected to respective connection points of the transistors 11 and 12, the transistors 13 and 14, and the transistors 15 and 16. This compressor 6
It is driven by a three-phase AC voltage from the power module 4.

In the power supply system, an active filter 5 is provided between the bridge rectifier circuit 2 as rectifying means and the smoothing capacitor 3 as smoothing means.
The active filter 5 includes a choke coil 7 and a high-speed recovery diode (hereinafter, referred to as a high-speed diode).
8 and a power transistor 9. In this embodiment, an insulated gate bipolar transistor is used as the power transistor 9, but another high-speed switching element may be used.

Choke coil 7 and high-speed diode 8
Are provided in series with one of the power supply lines on the rectifying side. Power transistor 9 as switching element
The collector is connected to a connection point between one end of the choke coil 7 and the anode of the high-speed diode 8, and the emitter is connected to the other (ground side) of the rectification-side power supply line.

The active filter 5 controls the amount of current flowing through the choke coil 7 by switching the power transistor 9 with respect to the current flowing into the smoothing capacitor 3 via the choke coil 7 and the high-speed diode 8. ing.

The inverter control unit includes a maximum frequency setting unit 3
1 and an operating frequency setting circuit 32.

The maximum frequency setting section 31 as the maximum frequency defining means sets the maximum operating frequency of the air conditioner according to the magnitude of the output voltage V _O of the active filter 5. The operating frequency setting circuit 32 as the power control means controls the control waveform such that the switching frequency in the power module 4 and the inverter voltage (input voltage to the compressor 6) do not rise to a predetermined value or more based on the maximum operating frequency. (Inverter waveform). As a result, the operating capacity of the compressor 6 is limited.

The active filter control section includes a thermistor 33, a resistor 34, an error amplifier 35, a reference power supply 36, an output voltage setting section 37, a reference power supply 38, an error amplifier 39, and a switching waveform generation section. 40.

The thermistor 33 as a temperature detecting means
It is provided close to the active filter 5, and particularly detects heat generated by the loss of the high-speed diode 8 and the power transistor 9. The thermistor 33 is connected in series with the resistor 34 and has one end grounded. The other end of the resistor 34 is connected to a power supply that outputs a DC voltage. Thermistor 33 and resistor 3
4 detects the temperature of the active filter 5 by outputting, as a detection voltage, the DC voltage divided by the thermistor 33 whose resistance changes according to the temperature and the resistor 34 as a detection voltage. It has become.

The connection point between the thermistor 33 and the resistor 34 is
It is connected to one input terminal of the error amplifier 35. The other input terminal of the error amplifier 35 has a reference power supply 3
6 are connected. The reference power supply 36 generates a reference voltage _Vref1 that determines a reference temperature. The error amplifier 35 outputs an error of the detection voltage with respect to the reference voltage _{Vref1 as} an error voltage.

The output voltage setting unit 37 as a correction means
Based on the error voltage from error amplifier 35, reference power supply 38
_Is corrected. Specifically, when the error voltage is large, that is, when the difference between the detected temperature and the reference temperature is large, the output voltage setting unit 37 _lowers the reference output voltage V _Oref as the target value according to the temperature difference. To be corrected. The error amplifier 39 outputs an error of the output voltage V _O with respect to the reference output voltage V _Oref corrected by the output voltage setting unit 37 as an error voltage.

The switching waveform generator 40 as switching control means controls the switching waveform applied to the control electrode of the power transistor 9 based on the error voltage from the output voltage setting unit 37, that is, the pulse width of the pulse-like switching control signal. It has become. Thereby, the output voltage of the active filter 5 is controlled. The switching waveform generator 40 generates a switching control signal based on the input current waveform and the input voltage waveform to the active filter 5 so that the input current waveform approaches the input voltage waveform. .

In the air conditioner configured as described above, when the temperature of the active filter 5 rises due to heat generated by the loss of the high-speed diode 8 and the power transistor 9, the resistance of the thermistor 33 decreases. As a result, the detection voltage input to the error amplifier 35 decreases, so that the error of the detection voltage with respect to the reference voltage _Vref1 increases, and the error voltage output from the error amplifier 35 increases.

In the output voltage setting section 37, the reference output voltage V
_Oref is corrected so as to decrease according to the increased error voltage. Specifically, the reference output voltage V _Oref is as shown in FIG.
As shown in (1), the error voltage (temperature difference) is constant up to the standard value. On the other hand, when the temperature difference exceeds its standard value, the reference output voltage V _Oref is corrected in an inversely proportional relationship that decreases as the temperature difference increases, as shown by the solid line in FIG. The correction is made so as to gradually decrease as shown by the broken line.

Then, the error of the output voltage V _O with respect to the corrected reference output voltage V _Oref increases, so that the error voltage from the error amplifier 39 increases. Then, the switching waveform generator 40 generates a switching waveform that eliminates the above error.

As a result, the switching voltage and the number of times of switching of the power transistor 9 are reduced, the switching operation of the power transistor 9 is restricted, and the current flowing through the high-speed diode 8 is reduced. As a result, the amount of heat generated by the high-speed diode 8 and the power transistor 9 decreases, and the output voltage V _O decreases.

When the self-heating of the active filter 5 becomes excessive, if the detected temperature rises above a predetermined value, the switching waveform generator 40 generates a switching waveform so as to stop the switching of the power transistor 9. I do. Thereby, abnormal operation or destruction of the high-speed diode 8 and the power transistor 9 due to abnormal temperature rise can be prevented.

On the other hand, in the power module 4, the driving capability of the compressor 6 is limited by the maximum frequency setting unit 31 and the operating frequency setting circuit 32 based on the output voltage V _O.
Therefore, even if the output voltage V _O decreases as described above,
The operation of the compressor 6 can be kept normal without the shortage of the inverter voltage.

As described above, in the present air conditioner, the switching of the power transistor 9 is controlled such that the output voltage V _O of the active filter 5 is reduced in accordance with the temperature rise of the active filter 5. Therefore, heat generation of the high-speed diode 8 and the power transistor 9 can be suppressed. Therefore, even if the temperature of the air conditioner becomes abnormally high due to an increase in the outside air temperature, an abnormal increase in the temperature detected by the thermistor 33 can be suppressed. As a result, the frequency of unnecessarily stopping the present air conditioner can be significantly reduced.

A reference example of the present embodiment will be described below with reference to FIGS. In addition,
In the present reference example , components having the same functions as the components in the first embodiment are denoted by the same reference numerals, and description thereof is omitted.

As shown in FIG. 3, the air conditioner according to this embodiment has a power supply system including a bridge rectifier circuit 2, a smoothing capacitor 3, a power module 4, and an active filter 5, an inverter control unit, an active filter And a control unit.

The inverter control unit includes an input voltage detection circuit 4
1, the maximum frequency setting unit 42, and the operating frequency setting circuit 3
And 2.

[0054] Input voltage detecting circuit 41, and outputs the average value of the input voltage V _in to the active filter 5. The maximum frequency setting unit 42 determines the maximum operation frequency of the present air conditioner according to the magnitude of the output voltage V _O of the active filter 5. The maximum frequency setting section 42 determines the maximum operating frequency to be a low value when at least one of the output voltage V _O and the above average value is lower than the respective standard value. Used to determine the maximum operating frequency an average value of the input voltage V _in is based on the input voltage V _in is major factor that determines the output voltage V _O.

The active filter control unit includes a reference power source 3
8, an error amplifier 39, a switching waveform generator 40
And The error amplifier 39 outputs an error of the output voltage V _O with respect to the reference voltage from the reference power supply 38 as an error voltage.

[0056] In the configured the air conditioner as described above, the input voltage V _in is the input voltage detection circuit 4 to the output voltage, that the active filter 5 from the bridge rectifier circuit 2
Is input to 1, the average value of the input voltage V _in from the input voltage detection circuit 41 is output. In the maximum frequency setting section 42, the maximum operation frequency is set based on the output voltage V _O.

At this time, if the output voltage V _O is lower than the standard value, the maximum operation frequency is set lower. Also, when the average value is lower than the standard value, the maximum operation frequency is set to be low. Specifically, as shown in FIG. 4, the maximum operating frequency is set to a constant value in a range where the output voltage V _O (detection voltage) or the above average value (detection voltage) is equal to or more than the respective standard value. On the other hand, the maximum operating frequency is corrected in a proportional relationship in which the detected voltage is lower as the detected voltage decreases as shown by a solid line in the range where the detected voltage is lower than the respective standard value, or The correction is made so as to gradually decrease as shown by the broken line.

Then, the operating frequency setting circuit 32 sets the actual operating frequency in a region lower than the input maximum operating frequency. Thereby, the power module 4
Even if the input voltage V _in is low, it drives the compressor 6 within the range and the maximum operating frequency of the acceptable load variations. Therefore, stably regardless of fluctuations in the input voltage V _in can be maintained operation.

As described above, the air conditioner of the present embodiment is
Rectifying means for rectifying the AC voltage output from the power supply,
Flatten the rectified AC voltage to a DC voltage
Smoothing means and chopping the DC voltage from this smoothing means
To change the AC voltage to a variable voltage and frequency.
Inverting means for exchanging and applying the same to the compressor;
The switching element is provided between the smoothing means and the switching element.
Adjust the amount of current flowing into the smoothing means by switching
By doing so, the input current is almost in phase with the input voltage.
The active filter is shaped into a sinusoidal waveform
Filter and the AC voltage or the active filter
Frequency that defines the maximum value of the above frequency according to the output voltage
Setting means.

In the above air conditioner, the frequency setting means
From the AC voltage or the output voltage of the active filter
The maximum value of the frequency in the inverse conversion means is set accordingly.
You. If the AC voltage is low, the output of the active filter
The voltage tends to be low. Especially, the operation load of the air conditioner
When the load is heavy, the tendency becomes remarkable.

Therefore, the AC voltage or the active fill
When the output voltage of the
Is set so that the pressure by the inverse conversion means is
Since the drive capability of the compressor is reduced,
Due to insufficient output voltage of the active filter (insufficient boost)
The operation of the compressor will not be unstable.

Therefore, the AC voltage is unstable and low.
In many cases, operate the air conditioner stably.
Can be .

Another reference example will be described below with reference to FIGS. 5 and 6. In the present reference example , components having the same functions as those in the first embodiment are denoted by the same reference numerals, and description thereof is omitted.

As shown in FIG. 5, the air conditioner according to this embodiment has a power supply system including a bridge rectifier circuit 2, a smoothing capacitor 3, a power module 4 and an active filter 5, an inverter control unit, an active filter And a control unit.

The inverter control section includes a thermistor 51,
It includes a resistor 52, an error amplifier 53, a reference power supply 54, a maximum frequency setting unit 55, and an operation frequency setting circuit 32. Moreover, the active filter control section is configured similarly to the A <br/> active filter controller of FIG.

The thermistor 51 as a temperature detecting means
It is provided close to the power module 4,
Heat generation due to switching loss in the power module 4 is detected. This thermistor 51
Is connected in series with the resistor 52 and has one end grounded. The other end of the resistor 52 is connected to a power supply that outputs a DC voltage.

The circuit formed by the thermistor 51 and the resistor 52 outputs the above-mentioned DC voltage divided by the thermistor 51 and the resistor 52 whose resistance value changes in accordance with the temperature as a detected temperature, thereby providing power. The temperature of the module 4 is detected.

The connection point between the thermistor 51 and the resistor 52 is
It is connected to one input terminal of the error amplifier 53. A reference power supply 5 is connected to the other input terminal of the error amplifier 53.
4 are connected. The error amplifier 53 includes a reference power source 54
The error of the detected voltage with respect to the reference voltage V _ref2 (the voltage that determines the reference temperature) is output as an error voltage.

The maximum frequency setting section 55 as maximum frequency defining means determines the maximum operation frequency of the air conditioner according to the magnitude of the error voltage from the error amplifier 53. Specifically, when the error voltage is large, that is, when the difference between the detected temperature and the reference temperature is large, the maximum frequency setting unit 55 determines that the maximum operating frequency has a low value according to the temperature difference.

In the present air conditioner configured as described above, when the temperature of the power module 4 rises due to heat generated by switching loss in the power module 4, the resistance value of the thermistor 51 decreases. For this reason, the detection voltage input to the error amplifier 53 decreases, so that the error of the detection voltage with respect to the reference voltage _Vref2 increases, and the error voltage output from the error amplifier 53 increases.

The maximum frequency setting section 55 sets the maximum operation frequency to be lower in accordance with the increased error voltage. Specifically, as shown in FIG. 6, the maximum operation frequency is constant when the error voltage (temperature difference) is equal to or less than a standard value. On the other hand, when the temperature difference exceeds the standard value, the maximum operating frequency is corrected in an inversely proportional relationship that decreases as the temperature difference increases, as shown by the solid line in FIG. The correction is made so as to gradually decrease as shown. Then, in the operating frequency setting circuit 32, an inverter waveform is generated according to the maximum operating frequency having a low value.

As a result, the operation capability of the power module 4 is suppressed, and the amount of heat generated by the switching loss of the power module 4 can be reduced. Therefore, even if the temperature of the air conditioner becomes abnormally high due to a rise in the outside air temperature, an abnormal rise in the temperature of the active filter 5 can be suppressed.

In the present air conditioner, when the self-heating of the power module 4 becomes excessive, if the detected temperature rises to a predetermined value or more, the operating frequency setting circuit 32 switches the switching of each element of the power module 4. Generate an inverter waveform to stop the operation. As a result, it is possible to prevent abnormal operation or destruction of each of the above-mentioned elements due to an abnormal temperature rise.

Therefore, by suppressing the abnormal temperature rise of the active filter 5 as described above, the frequency of unnecessarily stopping the present air conditioner can be greatly reduced.

The air conditioner of this reference example is output from an AC power supply.
Rectifying means for rectifying the applied AC voltage;
A smoothing means for smoothing the flowing voltage to be a DC voltage;
By chopping the DC voltage from the smoothing means
Voltage and frequency are converted to variable AC voltage
Inverse conversion means applied to the sensor and detecting the temperature of the inverse conversion means
Temperature detecting means, and required for driving the compressor
While setting the above frequency according to the driving capability,
The temperature detected by the temperature detecting means is equal to or higher than a predetermined value
Power control means for stopping the inverse conversion means,
According to the temperature detected by the temperature detecting means,
The maximum value of the frequency set by the power control means.
Maximum frequency defining means.

[0076] In the above air conditioner, the inverse conversion means operates at the frequency.
DC voltage based on the frequency set by the number setting means
To drive the compressor at that voltage. one
On the other hand, the temperature of the inverse converter is detected by the temperature detector.
And the maximum frequency regulating means
The maximum number is specified. That is, the temperature of the inverse conversion means
, The frequency is limited.

For example, if the temperature of the inverse conversion means rises,
The maximum value is set so that the frequency decreases accordingly.
Then, the maximum driving capability of the compressor by the inverse conversion means, that is,
Since the maximum operating capacity of the air conditioner decreases,
Heat generation is reduced. Therefore, the temperature of the inverse conversion means
If the air temperature becomes abnormally high, etc.
Even if the temperature rises due to heat generation, the power control means
Drastically reduces the frequency at which the inverse conversion means is stopped
be able to. Therefore, the abnormal high air
It is possible to maintain continuous operation of the air conditioner even at warm temperatures.
I can .

Next , another air conditioner of the present embodiment will be described.

As shown in FIG. 7, the present air conditioner has an inverter control section having an operation frequency setting circuit 32 and an active filter control section having the following configuration.

The active filter control section includes a thermistor 51, a resistor 52, an error amplifier 53, and a reference power supply 54.
, An output voltage setting section 37, a reference power supply 38, an error amplifier 39, and a switching waveform generation section 40.

The output voltage setting section 37 corrects the reference output voltage V _Oref from the reference power supply 38 based on the error voltage from the error amplifier 53. Specifically, when the error voltage is large, that is, when the difference between the detected temperature and the reference temperature is large, the output voltage setting unit 37 increases the reference output voltage V _Oref within a predetermined range according to the temperature difference. Correction as follows. This is because if the temperature difference becomes abnormally large _unless the correction range of the reference output voltage V _Oref is limited.
The reference output voltage V _Oref becomes too high and the output voltage setting unit 3
This is because there is an inconvenience that the withstand voltage of the circuit element at the subsequent stage of 7 is exceeded.

In the present air conditioner configured as described above, similarly to the air conditioner described above, the difference between the temperature of the power module 4 detected by the thermistor 51 and the reference temperature (reference voltage V _ref2 ) is obtained. Desired.

In the output voltage setting section 37, when the difference increases, the reference output voltage V _Oref is corrected so as to increase accordingly. Specifically, the reference output voltage V _Oref is
As shown in FIG. 8, the error voltage (temperature difference) is constant when it is equal to or less than the standard value. On the other hand, when the temperature difference exceeds the standard value, the reference output voltage V _Oref is corrected in a proportional relationship that increases as the temperature difference increases, as shown by a solid line in FIG. The correction is made so as to increase stepwise as shown by the broken line. In any case, the correction is performed in a range where the reference output voltage V _Oref does not exceed the upper limit value.

Then, the switching waveform generator 40 outputs the reference output voltage V _Oref output from the error amplifier 39.
Is output based on the error of the output voltage V _O with respect to.

As a result, the switching voltage and the number of times of switching of power transistor 9 increase, and output voltage V _O of active filter 5 increases. As a result, the voltage applied to the power module 4 increases, so that the current flowing through the power module 4 decreases. Therefore, the amount of heat generated by the switching loss of the power module 4 can be reduced. Therefore, even with the above configuration, when the temperature of the air conditioner becomes abnormally high, an abnormal temperature rise of the power module 4 can be suppressed, and the frequency of unnecessarily stopping the air conditioner is greatly reduced. Can be done.

The air conditioner of this reference example is powered by an AC power supply.
Rectifying means for rectifying the applied AC voltage;
A smoothing means for smoothing the flowing voltage to be a DC voltage;
By chopping the DC voltage from the smoothing means
Voltage and frequency are converted to variable AC voltage
, Rectifying means and smoothing means
Between the switching element
By adjusting the amount of current flowing into the smoothing means,
Input current is almost in phase with the input voltage and
An active filter that shapes it into a sinusoidal waveform
Increase the output voltage of the active filter to the target value.
Switch for controlling the switching of the switching element
And a temperature for detecting the temperature of the inverting means.
Detecting means and the temperature detected by the temperature detecting means.
Correction means for correcting the target value accordingly .

In the above air conditioner, the temperature detecting means
When the temperature of the inverse conversion means is detected, the correction means
The target value is corrected according to the temperature. For example, the inverse transformation
If the temperature of the means rises, the target value
Is corrected so as to be higher. This allows
The output voltage of the active filter rises,
Current can be reduced. Because of this, the switch
The self-heating of the switching element is suppressed and the temperature
Outflow temperature decreases.

As a result, the temperature of the inverting means becomes equal to the outside air temperature.
Self-heating of the inverse converter due to abnormally high temperature
Even if the temperature becomes higher than the
Significantly reduce the frequency at which conversion means are stopped
Can be. Therefore, even when the ambient temperature is abnormally high,
The effect that the continuous operation of the air conditioner can be maintained
To play.

[Embodiment 2 ] The following will describe a second embodiment of the present invention with reference to FIG. Note that, in the present embodiment, components having the same functions as the components in the first embodiment are denoted by the same reference numerals, and description thereof is omitted.

As shown in FIG. 9, the air conditioner according to the present embodiment has a bridge rectifier circuit 2, a smoothing capacitor 3,
The power supply system includes a power module 4 and an active filter 5, an inverter control unit including an operation frequency setting circuit 32, and an active filter control unit.

The active filter control section has an output voltage setting section 61, a reference power supply 38, an error amplifier 39, and a switching waveform generation section 40. The output voltage setting section 61 as a correction means sets the reference output voltage V _Oref from the reference power supply 38 according to the operation frequency information from the operation frequency setting circuit 32.

In the present air conditioner configured as described above, the output voltage setting section 61 outputs the reference output voltage V _Oref according to the operating frequency information. Then
A switching waveform is output from the switching waveform generator 40 based on the error voltage from the error amplifier 39.
As a result, the output voltage V _O of the active filter 5 is controlled to be equal to the reference output voltage V _Oref .

As described above, according to the present air conditioner, the output voltage V _O is controlled in accordance with the operation frequency, so that the applied voltage suitable for the power module 4, that is, the voltage necessary for the minimum operation capability can be obtained. Can be. Therefore, the switching loss in the power module 4 can be minimized.

[0094]

As described above, the air conditioner according to the first aspect of the present invention comprises a rectifier for rectifying an AC voltage output from an AC power supply and a rectifier for converting the rectified AC voltage to a DC voltage. A smoothing means for smoothing, an inverse conversion means for converting the DC voltage from the smoothing means into an alternating voltage having a variable voltage and frequency by applying chopping, and applying the AC voltage to the compressor; to provided, by adjusting the amount of current flowing into the smoothing means by switching a switching element, an active filter for shaping an input current and input voltage to substantially the same phase as the result and waveform becomes substantially sinusoidal, the active filter Temperature detection means for detecting a temperature, and switching of the switching element so that the output voltage of the active filter becomes a target value. With Gosuru, the active
A switching control unit that stops the switching element when the temperature of the filter is equal to or higher than a predetermined value; and a correction unit that corrects the target value according to the temperature detected by the temperature detection unit. .

Thus, the temperature of the active filter is detected, and the target value is corrected according to the detected temperature.
For example, if the correction is made so that the target value decreases in accordance with the temperature rise of the active filter, the amount of current flowing through the switching element decreases. Therefore, active
The self-heating of the filter is suppressed, and the temperature detected by the temperature detecting means decreases. Therefore, active such as by the temperature of the active filter, the outside air temperature becomes abnormally high
Even when the temperature becomes higher than the temperature due to the self-heating of the filter , the frequency at which the switching elements stop by the switching control means can be significantly reduced. Therefore, there is an effect that the continuous operation of the air conditioner can be maintained even when the temperature of the outside air is abnormally high as described above.

An air conditioner according to a second aspect of the present invention, in the first air conditioner, further comprises a maximum frequency defining means for defining a maximum value of the frequency according to an output voltage of the active filter. Configuration.

Thus, when the output voltage of the active filter decreases due to the decrease in the target value as described above, the maximum value of the frequency is set accordingly.
For example, the correction is performed so that the maximum value of the frequency decreases in accordance with the decrease in the output voltage of the active filter. Therefore, the maximum driving capability of the compressor by the inverting means, that is, the maximum operating capability of the air conditioner is reduced, so that even if the output voltage of the active filter decreases, the compressor can be driven with the capability corresponding thereto. . Therefore, there is an effect that the air conditioner can be stably operated regardless of a change in the output voltage of the active filter.

An air conditioner according to a third aspect of the present invention includes: a rectifier for rectifying an AC voltage output from an AC power supply;
Smoothing means for smoothing the rectified AC voltage so as to become a DC voltage, and inverting means for converting the DC voltage from the smoothing means into an AC voltage having a variable voltage and frequency by applying chopping to the compressor. Power control means for setting the frequency in accordance with the driving capability required for driving the compressor, and provided between the rectification means and the smoothing means, switching the switching element to the smoothing means By adjusting the amount of current flowing in,
An active filter for shaping the input current into a waveform having substantially the same phase as the input voltage and a substantially sine wave, and switching control means for controlling switching of the switching element so that the output voltage of the active filter becomes a target value. And a correcting means for correcting the target value in accordance with the frequency set by the power control means.

As a result, the target value is corrected in accordance with the set frequency, so that the output voltage of the active filter is controlled in accordance with the driving capability of the compressor (the operating capability of the air conditioner) by the inversion means. . Therefore, the output voltage of the active filter does not become higher than required by the inverter, and the loss in the chopping operation of the inverter can be reduced. Therefore, there is an effect that unnecessary power consumption can be reduced and the air conditioner can be operated with high efficiency.

[Brief description of the drawings]

FIG. 1 is a circuit diagram showing a configuration of an air conditioner according to a first embodiment of the present invention.

FIG. 2 is a graph showing correction of a reference output voltage based on a temperature difference between an active filter temperature and a reference temperature in the air conditioner of FIG.

FIG. 3 is a circuit diagram illustrating a configuration of an air conditioner according to a reference example .

FIG. 4 is a graph showing correction of a maximum operating frequency based on a detected voltage in the air conditioner of FIG.

FIG. 5 is a circuit diagram showing a configuration of an air conditioner according to another reference example .

6 is a graph showing a correction of a maximum operating frequency based on a temperature difference between a temperature of an inverter module and a reference temperature in the air conditioner of FIG.

FIG. 7 is a circuit diagram showing a configuration of another air conditioner according to still another reference example .

FIG. 8 is a graph showing a correction of a reference output voltage based on a temperature difference between an inverter module temperature and a reference temperature in the air conditioner of FIG. 7;

FIG. 9 is a circuit diagram showing a configuration of an air conditioner according to a second embodiment of the present invention.

FIG. 10 is a circuit diagram showing a configuration of a conventional air conditioner.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Commercial power supply (AC power supply) 2 Bridge rectifier circuit (rectifying means) 3 Smoothing capacitor (smoothing means) 4 Power module (inverting means) 5 Active filter 6 Compressor 9 Power transistor (switching element) 31 ・ 42 ・ 55 Maximum frequency Setting section (maximum frequency defining means) 32 operating frequency setting circuit (power control means) 33.51 thermistor (temperature detecting means) 37.61 output voltage setting section (correction means) 40 switching waveform generating section (switching control means) 41 input Voltage detection circuit

──────────────────────────────────────────────────続 き Continued on front page (58) Field surveyed (Int.Cl. ⁷ , DB name) H02M 7/48 H02P 7/63 302

Claims (3)

(57) [Claims] 1. A rectifying means for rectifying an AC voltage output from an AC power supply, a smoothing means for smoothing the rectified AC voltage to be a DC voltage, and a chopping of the DC voltage from the smoothing means. Inverting means for converting the voltage and frequency into variable AC voltages and applying the AC voltage to the compressor, and provided between the rectifying means and the smoothing means, for adjusting the amount of current flowing into the smoothing means by switching of a switching element. by an active filter for shaping an input current and input voltage to substantially the same phase as the result and waveform becomes substantially sinusoidal, a temperature detecting means for detecting the temperature of the active filter, the target value the output voltage of the active filter controls the switching of the switching element so that the temperature of the active filter is In the air conditioner having a switching control means for stopping the switching element when it is value or more, that it comprises a correcting means for correcting the target value according to the temperature detected by said temperature detecting means An air conditioner characterized by the following. 2. The air conditioner according to claim 1, further comprising maximum frequency defining means for defining a maximum value of the frequency according to an output voltage of the active filter. 3. The rectifier for rectifying an AC voltage output from an AC power supply.
Rectifying means for smoothing the rectified AC voltage to a DC voltage.
And chopping the DC voltage from the smoothing means.
Convert to more variable voltage and frequency AC voltage and compress
The reverse conversion means to be applied to the compressor, and the driving capability required for driving the compressor.
A power control means for setting a frequency, and a switch provided between the rectifying means and the smoothing means.
Flow into the smoothing means by switching of the switching element
The input current to the input voltage by adjusting the amount of
Shapes waveforms that are almost in phase and almost sinusoidal
The active filter and the output voltage of the active filter are set to target values.
Switches that control the switching of the switching elements
Switching control means and the frequency set by the power control means.
An air conditioner comprising: a correction unit that corrects the target value .