JP3146446B2 - 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, and more particularly, to an air conditioner having a power converter and an inverter.

[0002]

2. Description of the Related Art A conventional example of a motor driving apparatus using a power converter having a high power factor for suppressing harmonics of an input current as a power supply is disclosed in, for example, Japanese Patent Publication No. 7-89743. FIG. 12 is a block diagram showing such a conventional motor driving device, wherein 1 is an AC power supply, 2 is a rectifier, 2a, 2b, 2
c and 2d are diodes, 3 is a reactor, 4 is a diode, 5 is a capacitor, 6 is a switch element, 7 is a voltage comparator, 8 is a multiplier, 9 is a load current detector, 10 is a current comparator, and 11 is an oscillator. , 12 is a drive circuit, 13 is an inverter, 14 is a motor, 15 is a microcomputer, 16 is an inverter drive circuit, and 17 is a modulator.

In FIG. 1, a rectifier 2, a reactor 3,
Diode 4, capacitor 5, switch element 6, voltage comparator 7, multiplier 8, load current detector 9, current comparator 1
0, an oscillator 11, a drive circuit 12, and a modulator 17 constitute a power converter, and the inverter 13 uses the power converter as a power source.

[0004] First, this power converter will be described.

[0005] The AC power supply voltage from the AC power supply 1 is full-wave rectified by a rectifier 2 comprising diodes 2a to 2d and converted into a rectified voltage Es. This rectified voltage Es is applied to the capacitor 5 via the reactor 3 and the diode 4,
A smoothed DC voltage Ed is obtained. A switching element 6 is provided in parallel with the diode 4 and the capacitor 5.

The DC voltage Ed smoothed by the capacitor 5 is divided by the resistors R3 and R4 to form a DC voltage Ed ', and a deviation value between the DC voltage Ed' and the reference voltage Eo is obtained by the voltage comparator 7 to control the voltage. A signal Ve is created.

The rectified voltage Es obtained by full-wave rectification of the sine-wave AC power supply voltage by the rectifier 2 also includes resistances R1 and R
2, a sine wave synchronization signal Es' is obtained, and the sine wave synchronization signal Es' and the voltage control signal Ve from the voltage comparator 7 are operated by the multiplier 8 to form the current reference signal Vi '. Is done. This current reference signal Vi ′ is supplied to the load current detector 9.
Is compared with the current signal Vi obtained by
A modulated signal Vk is obtained. This modulation signal Vk is applied to the modulator 1
7 modulates the sawtooth or triangular carrier wave Vk ′ from the oscillator 11 and changes the duty ratio according to the modulation signal Vk.
g is created. With this switching drive signal Vg, the drive circuit 12 drives the switching element 6 on and off.

As described above, in this conventional example, the switching element 6 is turned on and off while following the waveform of the sine-wave rectified voltage Es, whereby the input AC current i is changed at a high power factor. A sinusoidal current with few harmonics can be obtained, and the conduction ratio of the switching element 6 is changed according to the deviation value between the reference voltage Eo and the DC voltage Ed. Regardless, a stable DC voltage Ed is obtained. Therefore, it is described that by appropriately setting the reference voltage Eo and the resistance values of the resistors R3 and R4, the DC voltage Ed can be set to a desired voltage value, and the input AC power can be converted to a DC output. I have.

Next, the motor drive circuit shown in FIG. 12 will be described.

The DC power generated by the power converter is inversely converted into AC power by an inverter 13 and supplied to a motor 14 for driving the same. In addition, a PWM signal calculated and output from the microcomputer 15 based on the speed command is supplied to the inverter 13 via the inverter driving circuit 16, whereby the inverter 13 is driven, and its switching element (not shown) is driven. On / off operation is performed at a predetermined duty ratio.

In the motor driving device having the above configuration, the DC voltage Ed can be obtained stably even if the input AC power supply voltage changes, but the DC voltage Ed changes according to the voltage value of the input AC power supply voltage. If so, it is necessary to correct the circuit constants. In particular, in the above conventional example, since the power converter is of the boosting type, in order to perform stable control, the input AC power supply voltage is set to 100 V by the following equation: DC voltage Ed ≧ AC power supply voltage × 1.41 + 10 [V] In the case of, 15
The DC voltage Ed is set to 0 V or more, and the DC voltage Ed is set to 300 V or more when the input AC power supply voltage is 200 V.

Therefore, when the AC power supply 1 is 100V and 200V
In the case of a power converter that can use either of the above, the set value of the DC voltage Ed needs to be 300 V or more.

For example, in the case of an input AC power supply voltage of 100 V, the DC voltage Ed is set to a constant voltage of about 300 V,
The loss can be reduced by controlling the inverter 13 at an arbitrary DC voltage Ed of 150 V or more without a chopper having a 100% duty ratio, as compared with performing the rotation speed control by driving the inverter 13 with a chopper at an arbitrary duty ratio. However, in the above-mentioned conventional example, since this point is not taken into consideration, there is a problem that the loss is increased more than necessary.

In the above conventional example, a sine-wave rectified voltage Es obtained by full-wave rectification of an AC power supply voltage from an AC power supply 1 is divided by resistors R1 and R2 to obtain a sine-wave synchronization signal Es'.
And a voltage control signal Ve is calculated by the multiplier 8 to generate a current reference signal Vi ′.
Since the input AC current is controlled in a sine wave form with reference to i ′, the rectified voltage Es is different between the AC power supply voltages of 100 V and 200 V, and the shapes and values of the sine waves are significantly different between the two. Therefore, the AC power supply voltage is set to 100
When shared between V and 200V, the power converter has a low power factor and a high harmonic content.

Further, in the motor drive device and the air conditioner using the above-described power converter, when using 100V and 200V as the AC power supply voltage, the power converter must have specifications corresponding to the respective specifications. Therefore, problems such as an increase in the number of models and a decrease in production efficiency occur.

Further, when the input AC current is small, and especially when the above control is not necessary, it is considered to conversely eliminate the unstable operation, loss, noise, etc. of the control at the time of low input current. Absent.

For example, when a resistor is used as the load current detector 9 and a current signal Vi is to be obtained from a voltage generated at both ends, a sufficient voltage for controlling a small current is generated. More specifically, it is necessary to set a large resistance value of this resistor. In this case, when the load current increases, the power consumed by the resistor increases, resulting in an increase in loss.

Further, in the inverter 13, the DC power supply voltage Ed is kept constant, and the DC power supply voltage Ed is chopped at a duty ratio corresponding to the duty ratio of the PWM signal from the microcomputer 15, so that the DC power supply voltage Ed is changed according to the duty ratio. The electric motor 14 rotates at the predetermined rotation speed. By changing the duty ratio, the number of revolutions of the motor 14 changes. In such a conventional motor drive device, however, the inverter 1 always operates as described above.
3 is driven by a chopper, which causes a power loss (chopper loss), which inevitably lowers the efficiency.

[0019]

The conventional air conditioner is
When commonly connected to AC power supplies of different input AC power supply voltages, when the input AC power supply voltage is low, the output DC voltage is maintained at a low predetermined value in the low rotation speed region of the motor, and the switching element of the inverter is It is not possible to control the number of revolutions of the motor by changing the duty ratio, so that there is a problem that the loss in the inverter or the motor increases, and the efficiency decreases.

Further, when the input AC power supply voltage is shared and connected to an AC power supply having a different input AC power supply voltage, a method of controlling the motor rotation speed in a low rotation speed region and a high rotation speed region of the motor when the input AC power supply voltage is low. Cannot be switched, and furthermore, the output DC voltage is kept at a low predetermined value in the low rotation speed region of the motor, and the rotation speed of the motor cannot be controlled by changing the duty ratio of the switch element of the inverter. In addition, the loss in the inverter or the motor increases, and the duty ratio of the switch element of the inverter is maintained at a high predetermined value in a high rotation speed region of the motor, and the output DC voltage is changed to control the rotation speed of the motor. However, the switching loss of the inverter increases. For this reason, when the input AC power supply voltage is low, there is a problem that the efficiency of the motor is low from a low rotation speed region to a high rotation speed region.

Further, since the rectified voltage waveform is significantly different depending on the type of the input AC power supply voltage, if the input AC power supply voltage of different types is used in common, the power factor is reduced and the content of harmonics becomes high. There was a problem that would.

An object of the present invention is to provide an output DC motor in a low rotation speed region of an electric motor when the input AC power supply voltage determined by the determination means is low, even if the input AC power supply voltage is shared by AC power supplies having different input AC power supply voltages. By maintaining the voltage at a low predetermined value and controlling the rotation speed of the motor by changing the duty ratio of the switch element of the inverter, the loss in the inverter or the motor can be reduced and the efficiency can be improved. Another object of the present invention is to provide an air conditioner that has been improved.

Another object of the present invention is to provide a motor having a low rotation speed range when the input AC power supply voltage determined by the determination means is low, even if the input AC power supply voltage is different and shared. The rotation speed control method of the motor is switched between the high rotation speed region and the output DC voltage is maintained at a low predetermined value in the low rotation speed region of the motor, and the duty ratio of the switch element of the inverter is changed to reduce the rotation speed of the motor. By controlling the motor, the loss in the inverter or the motor can be reduced, and the duty ratio of the switch element of the inverter is maintained at a high predetermined value in the high rotation speed region of the motor, and the output DC voltage is changed to control the rotation speed of the motor. To provide an air conditioner that can reduce the switching loss of the inverter and improve the efficiency of the motor from a low rotation speed region to a high rotation speed region. Lies in the fact.

Still another object of the present invention is to provide a power supply system which is connected to an AC power supply of a different type of input AC power supply voltage.
It is an object of the present invention to provide an air conditioner that can operate in a state with a high power factor and a small number of harmonics and can also suppress an adverse effect on an AC power supply.

[0025]

In order to achieve the above object, the present invention relates to an air conditioner having an electric motor driving device for driving a compressor, wherein the electric motor driving device is connected to an AC power supply and has an input. A power converter that rectifies and boosts an AC power supply voltage and outputs a DC voltage, outputs a DC voltage, an inverter that uses the output DC voltage of the power converter as a power supply voltage, a control device that controls the power converter and the inverter, An electric motor driven by an inverter, wherein the power converter has switch means that is turned on and off so as to change the output DC voltage, and the inverter has a switch element that is turned on and off. The control device includes: a determination unit configured to determine a type of the input AC power supply voltage; and when the input AC power supply voltage determined by the determination unit is low, the control unit operates in a low rotation speed region of the motor. The output DC voltage is maintained at a low predetermined value and the duty ratio of the switch element of the inverter is changed to control the rotation speed of the motor.When the input AC power supply voltage is high, the rotation speed of the motor is controlled in a low rotation speed region. Control means for controlling the number of revolutions of the motor by changing the duty ratio of the switch element of the inverter while maintaining the output DC voltage at a high predetermined value.

Further, the present invention relates to an air conditioner having a motor driving device for driving a compressor, wherein the motor driving device is connected to an AC power supply, rectifies and boosts an input AC power supply voltage to generate a DC voltage. A power converter for outputting, an inverter using a DC voltage output from the power converter as a power supply voltage, a control device for controlling the power converter and the inverter, a motor driven by the inverter, and detecting a room temperature. And a room temperature sensor that supplies the detection signal to the control device, the power conversion device includes switch means that is turned on and off so as to change the output DC voltage, and the inverter is turned on and off. A control device for controlling the type of the input AC power supply voltage; comparing the measured room temperature detected by the room temperature sensor with a set temperature; Means for responsively changing the duty ratio of the switch element of the inverter, and when the input AC power supply voltage determined by the determination means is low, the output DC voltage is held at a low predetermined value in a low rotation speed region of the motor. At the same time, the rotation speed of the motor is controlled by changing the duty ratio of the switch element of the inverter, and when the input AC power supply voltage is high, the output DC voltage is maintained at a high predetermined value in a low rotation speed region of the motor. And control means for controlling the number of revolutions of the electric motor by changing the duty ratio of the switch element of the inverter.

Further, the present invention relates to an air conditioner having a motor drive device for driving a compressor, wherein the motor drive device is connected to an AC power supply, rectifies and boosts an input AC power supply voltage to generate a DC voltage. An output power converter, and an inverter that uses an output DC voltage of the power converter as a power supply voltage,
A control device for controlling the power converter and the inverter;
An electric motor driven by the inverter, wherein the power conversion device has switch means that is turned on and off so as to change the output DC voltage, and the inverter has a switch element that is turned on and off. The control device has a determination unit that determines a type of the input AC power supply voltage,
When the input AC power supply voltage determined by the determination means is low, the output DC voltage is maintained at a low predetermined value in a low rotation speed region of the motor, and the duty ratio of a switch element of the inverter is changed to change the motor. Controlling the rotation speed of the motor, controlling the rotation speed of the motor by changing the output DC voltage while maintaining the duty ratio of the switch element of the inverter in a high rotation speed region of the motor and changing the output DC voltage. Control means for controlling the number of rotations of the motor by maintaining the output DC voltage at a high predetermined value in a low rotation speed region of the motor when the AC power supply voltage is high and changing the duty ratio of a switch element of the inverter; Is provided.

Preferably, when the input AC power supply voltage determined by the determination means is low, the control device holds the output DC voltage at a low predetermined value in a low rotation speed region of the electric motor, and controls the inverter. Controlling the rotation speed of the motor by changing the duty ratio of the switch element, maintaining the duty ratio of the switch element of the inverter at 100% in the high rotation speed region of the motor, and changing the output DC voltage. Controlling the rotation speed of the electric motor,
And a control means.

Further, the present invention relates to an air conditioner having a motor driving device for driving a compressor, wherein the motor driving device is connected to an AC power supply, rectifies and boosts an input AC power supply voltage to generate a DC voltage. A power converter that outputs the power, an inverter that uses the output DC voltage of the power converter as a power supply voltage, a control device that controls the power converter and the inverter, and a motor that is driven by the inverter. The converter includes a capacitor for smoothing a rectified voltage obtained by the rectifier and supplying a DC voltage to the inverter, and a switch connected between the rectifier and the capacitor and controlled on and off by a drive signal. Generating a signal for controlling the switch means using the rectified voltage so that the load current of the power converter follows the rectified voltage waveform. And a stage, the inverter is turned on, a switch element to be turned off controlled, the control device includes a discriminating means for discriminating the type of the input AC supply voltage,
Setting means for selecting and setting a control value of the power factor improvement signal generating means according to the type of the input AC power supply voltage determined by the determining means; and when the input AC power supply voltage determined by the determining means is low, When the input AC power supply voltage is high, the output DC voltage is maintained at a low predetermined value in the low rotation speed region of the motor and the duty ratio of the switch element of the inverter is changed to control the rotation speed of the motor. And control means for controlling the number of rotations of the motor by maintaining the output DC voltage at a high predetermined value in a low rotation speed region of the motor and changing the duty ratio of a switch element of the inverter. It is.

With this configuration, when the input AC power supply voltage determined by the determination unit is low, the output DC voltage is low in the low rotation speed region of the motor even if the input AC power supply voltage determined by the determination unit is low even if the input AC power supply voltage is shared and connected to AC power supplies of different input AC power supply voltages. Since the rotation speed of the motor is controlled by changing the duty ratio of the switch element of the inverter while maintaining the predetermined value, the loss in the inverter or the motor can be reduced.

Further, even if the input AC power supply voltage is different and the AC power supply voltage is shared by the AC power supply voltage, when the input AC power supply voltage determined by the determination means is low, the motor operates in the low rotation speed region and the high rotation speed region of the motor. The rotation speed control method is switched to maintain the output DC voltage at a low predetermined value in the low rotation speed region of the motor, change the duty ratio of the switching element of the inverter, and control the rotation speed of the motor to control the rotation speed of the inverter or the motor. In the high rotation speed region of the motor, the duty ratio of the switching element of the inverter is maintained at a high predetermined value, and the output DC voltage is changed to control the rotation speed of the motor to reduce the switching loss of the inverter. it can. Furthermore, even if the common AC power supply is connected to AC power supplies of different types of input AC power supply voltage, it can operate with a high power factor and a small number of harmonics.

[0032]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a block diagram showing a first embodiment of an air conditioner according to the present invention, in which 18 is a DC voltage switch, 19 is a trigger element, 20 is a synchronous signal switch, and 21 is a voltage command switch. A switch 22, a drive signal changeover switch 23, an input current detector 23, an active converter block 24, and an LPF (low-pass filter) 25, parts corresponding to those in FIG. I do.

In FIG. 1, a DC voltage Ed obtained by smoothing with a capacitor 5 is divided by a voltage dividing circuit composed of resistors R4, R5 and R6 to form DC voltages Ed1 and Ed2. Here, Ed1 = Ed × (R5 + R6) / (R4 + R5 + R6) Ed2 = Ed × R6 / (R4 + R5 + R6), and Ed1> Ed2.

The DC voltage Ed1 is a DC voltage switch 1
The DC voltage Ed2 is supplied to the contact A of the changeover switch 8 at the contact B of No. 8 respectively. This DC voltage switch 18
Is the divided voltage Ed of the DC voltage Ed by the microcomputer 15
1 in accordance with the DC voltage changeover switch 1
8 outputs the selected one of the DC voltages Ed1 and Ed2 as the DC voltage Ed1 '.

The output DC voltage Ed1 'of the DC voltage switch 18 is supplied to the contact B of the voltage command switch 21. The contact point A of the voltage command changeover switch 21 is supplied with a DC voltage Ed2 'formed by smoothing a PWM signal output from the microcomputer 15 for speed control of the electric motor 14 by the LPF 25. This voltage command changeover switch 21 is also switched by the microcomputer 15 and is controlled.
When the motor load is smaller than 100%,
The contact B side has a large motor load and a duty ratio of 10
When it is 0%, the contact A side is selected respectively.

One of the DC voltages Ed1 'and Ed2' selected by the voltage command switch 21 is the DC voltage E1.
The voltage control signal Ve is supplied to the voltage comparator 7 as d ', and a deviation value from the reference voltage Eo is obtained to form a voltage control signal Ve.

In the conventional example shown in FIG. 12, the voltage control signal Ve is obtained by comparing one type of DC voltage Ed ′ obtained by dividing the DC voltage Ed smoothed by the capacitor 5 with the reference voltage Eo. However, in the first embodiment, one of the two types of DC voltages Ed1 and Ed2 obtained by dividing the DC voltage Ed and the DC voltage Ed2 ′ obtained from the LPF 25 is used as the DC voltage Ed. 'age,
This is obtained by comparing this with the reference voltage Eo.

On the other hand, the rectified voltage Es of the sine wave full-wave rectified waveform output from the rectifier 2 is divided by a voltage dividing circuit composed of resistors R1, R2 and R3 to form voltages Es1 and Es2. Here, Es1 = Es × (R2 + R3) / (R1 + R2 + R3) Es2 = Ed × R3 / (R1 + R2 + R3), and Es1> Es2.

The voltage Es1 is supplied to the contact B of the synchronous signal changeover switch 20, and the voltage Es2 is supplied to the contact A of the synchronous signal changeover switch 20. The synchronization signal changeover switch 20 is also switched by the microcomputer 15 in accordance with the divided voltage Ed1 of the DC voltage Ed smoothed by the capacitor 5, similarly to the DC voltage changeover switch 18, and the output from the synchronization signal changeover switch 20 is controlled. The applied voltage Es1 or Es2 is supplied to the multiplier 8 as a sine wave synchronization signal Es ′.

The current reference signal Vi 'is obtained from the multiplier 8, and the ON / OFF control of the switch element 6 is performed using this signal in the same manner as in the conventional example shown in FIG.

As described above, also in the first embodiment, the switch element 6 is turned on and off while following the waveform of the rectified voltage Es of the sine wave full-wave rectified waveform. A sinusoidal input AC current with a high power factor and few harmonics can be obtained, and the reference voltage Eo
Since the conduction ratio of the switching element 6 is changed in accordance with the deviation value between the DC voltage Ed 'and the DC voltage Ed', a stable DC voltage Ed can be obtained regardless of the load fluctuation. Therefore, the DC voltage Ed can be set to a desired voltage value by appropriately setting the reference voltage Eo and the resistance values of the resistors R4, R5, and R6.

Here, the microcomputer 15 detects the input AC current Is by the input current detector 23,
A trigger signal VT of “L” (low level) is supplied to the trigger element 19 until the current value of the input AC current Is becomes a predetermined value or more. The trigger element 19 controls the drive circuit 12 during the “L” period of the trigger signal VT to turn off the switch element 6. When the trigger signal VT changes from “L” to “H” (high level), at this point, the trigger element 19 puts the switch element 6 into an operating state.

The PWM output from the microcomputer 15
The signal is supplied to an inverter drive circuit 16 via a drive signal switching switch 22 which is normally closed on the setting A side. The inverter drive circuit 16 controls the inverter 13 at a duty ratio corresponding to the duty ratio of the PWM signal. ON / OFF control of the switch elements not to be performed. This allows
In the inverter 13, the DC power of the DC voltage Ed supplied from the capacitor 5 is chopped at this duty ratio and converted into AC power, supplied to the electric motor 14 and rotated at a rotational speed according to the duty ratio of the PWM signal.

Next, a control operation method according to the first embodiment will be described with reference to FIG. 2, taking a domestic case as an example. In the case of Japan, the AC power supply voltage is 100 V
And 200V.

First, when the power is turned on (step 10)
0), the microcomputer 15 is set to the initial state, whereby the microcomputer 15 switches the DC voltage changeover switch 18 and the synchronization signal changeover switch 20 to the contact A side, the voltage command changeover switch 21 to the contact B side, and switches the drive signal. Switch 22
Are respectively closed to the contact A side. As a result, the DC voltage changeover switch 18 selects the DC voltage Ed2, and the following DC voltage Ed ′, Ed ′ = Ed × R6 / (R4 + R5 + R6) is supplied to the voltage comparator 7. In the synchronization signal changeover switch 20,
The sine wave synchronization signal Es2 is selected.

In this state, the charging operation is started by the capacitor 5, and the microcomputer 15 detects the divided voltage Ed1 of the DC voltage Ed of the capacitor 5 (Step 101). From the voltage value of the detected DC voltage Ed1, from the voltage value Ed = Ed1 × (R4 + R5 + R6) / (R5 + R6), if the DC voltage Ed is higher than 160 V, for example (step 102), it is determined that the input AC power supply voltage is 200V. Then, the DC voltage switch 18 is kept closed at the contact A (step 103). As a result, the DC voltage Ed ′ becomes the DC voltage Ed2, and the DC voltage Ed obtained in the capacitor 5 becomes Ed = Ed2 × {1+ (R5 + R4) / R6}.

The synchronization signal changeover switch 20 is set to the contact A
(Step 104). Therefore, the sine wave synchronization signal Es 'at this time is as follows: Es' = Es × R3 / (R1 + R2 + R3).

On the other hand, when the DC voltage Ed is, for example, 120 V
If it is lower (step 102), it is determined that the input AC power supply voltage is 100 V and the DC voltage switch 18
Is switched to the contact B side (step 110). Therefore,
The DC voltage Ed of the capacitor 5 is given by Ed = Ed1 × {1 + R4 / (R5 + R6)}.

When the synchronization signal changeover switch 20 is set to the contact B
(Step 111). Therefore, the sine wave synchronization signal Es 'at this time is as follows: Es' = Es × (R2 + R3) / (R1 + R2 + R3)

As described above, by controlling the switching of the DC voltage switch 18 and the synchronizing signal switch 20 according to the magnitude of the input AC power supply voltage, when the input AC power supply voltage is 200 V, the DC voltage Ed 'and the sine The wave synchronizing signal Es' is a lower DC voltage Ed2, Es2, respectively,
When the input AC power supply voltage is 100 V, the DC voltage E
d 'and the sine-wave synchronization signal Es'
d1 and Es1. Thus, the DC voltage Ed ′ is different between when the input AC power supply voltage is 100 V and when the input AC power supply voltage is 200 V.
Can be suppressed, the control becomes unstable due to the amplitude of the voltage control signal Ve becoming too large and becoming saturated, and the current reference signal Vi calculated from the sine wave synchronization signal Es' and the voltage control signal Ve. 'Can be prevented, and the current waveform can no longer be a sine wave.

In this embodiment, the input AC power supply voltage is of two types, 100 V and 200 V. In general, the input AC power supply voltage is of n types of V1, V2,..., Vn, and the DC voltage Ed is Similarly, “Es” is also set to n types, and it is determined whether the input AC power supply voltage is V1, V2,..., Vn, and according to the determination result, the DC voltage corresponding to the input AC power supply voltage is determined. The same effect can be obtained by setting Ed 'and Es'.

In step 102, when the input AC power supply voltage is 20
When it is determined that the voltage is 0 V, the voltage command changeover switch 21 is kept closed to the contact B side (step 105). At this time, it is almost E0 = Ed ′, and therefore, the DC voltage Ed is as follows: Ed = E0 × {1+ (R5 + R4) / R6}. In this case, for example, Ed = 300V.

At this time, the drive signal switching switch 22 is kept closed to the contact A (step 105), and the PWM signal output from the microcomputer 15 is driven by the drive signal switching switch 22 via the drive signal switching switch 22. It is supplied to the circuit 16.

By the above operation, the DC power Ed generated by the power converter is inversely converted into AC by the inverter 13,
As a result, the electric motor 14 is driven (step 10).
6). The microcomputer 15 generates and outputs the above-described PWM signal by an operation based on the speed command, similarly to the conventional example shown in FIG.
The inverter 13 is driven via the
The switching element 3 is turned on and off at a predetermined duty ratio according to the duty ratio of the PWM signal to control the rotation speed of the electric motor 14.

Generally, when the AC power supply voltage is V
One of Vj (j = 1, 2,..., Vn,..., Vn)
, N), the DC voltage Ed ′ corresponding to the input AC power supply voltage Vj is compared with a constant reference voltage Eo, and the DC voltage Ed obtained by rectifying and smoothing the input AC power supply voltage Vj is calculated. An arbitrary constant value (for example, 300 V) is set, and the switch element of the inverter 13 is turned on and off at an arbitrary duty ratio.

In the booster circuit, when this DC voltage Ed is reduced below the full-wave rectified voltage Es of the input AC power supply voltage, the power factor is reduced and the input current waveform is disturbed. To avoid this problem, if it is determined that the voltage is 200 V, Ed = 3
Control is performed with 00V constant. Of course, Ed = 300V
It is a condition that the desired rotation speed of the electric motor 14 can be obtained. Even if the voltage is increased to 300 V or more, the gist of the present invention is not impaired.

The microcomputer 15 detects the input AC current Is with the input current detector 23 (step 107), and outputs a trigger signal VT of "H" to the trigger element 19 during a period when the input AC current Is is large. The operation is continued (step 109) by turning on and off the switch element 6 (step 108).

Even when it is determined in step 102 that the input AC power supply voltage is 100 V, the voltage command switch 21 is kept closed to the contact B (step 112). Therefore, similar to the above, almost E0 = E
d ′, and the DC voltage Ed becomes Ed = E0 × {1 + R4 / (R5 + R6)}. In this case, for example, Ed = 150V. In this way, the capacitor 5 is shared while sharing the reference voltage E0.
Can be set to a voltage value different from that when the input AC power supply voltage is 200 V.

At this time, the duty ratio of the inverter 13 is 10
If it is less than 0% (step 116), step 10
In the same manner as in steps 5 and 106, the motor 14 is driven (steps 112 and 113).
Similarly, the switch element 6 is turned on and off (steps 114 and 115), and the operation is continued as it is (step 118).

However, during operation at an input AC power supply voltage of 100 V, for example, the motor load increases and the inverter 1
If the duty ratio of the switch element in step 3 becomes 100% (step 116), the voltage command changeover switch 21 is set to the contact A side, and the drive signal changeover switch 22 is set to the contact B.
Side (step 117).

As a result, the switch element drive signal (PWM signal) from the microcomputer 15 calculated based on the speed command is converted into a DC voltage Ed that has been smoothed by the LPF 25.
2 ′ is output from the voltage command changeover switch 21 as the DC voltage Ed ′, and the voltage control signal Ve formed from the DC voltage Ed ′ is supplied to the voltage comparator 7. Accordingly, the DC voltage Ed at the capacitor 5 becomes, for example, 150
On / off control of the switch element 6 is performed so that the voltage becomes an arbitrary voltage equal to or higher than V. At the same time, the drive signal switching switch 22 is switched to the contact B side, so that a voltage Ei for driving the inverter 13 at a duty ratio of 100% is supplied to the inverter drive circuit 16 via the drive signal switching switch 22. Supplied.

Here, the above operation of this embodiment when the input AC power supply voltage is 100 V will be described in more detail with reference to FIG. 3, taking the case of the heating operation of the air conditioner as an example. FIG. 3 is the same as FIG. 1 except that the room temperature sensor 29 is additionally shown.

In the figure, the air conditioner is provided with a room temperature sensor 29, and the microcomputer 15 detects the room temperature by the room temperature sensor 29 (this detected temperature is hereinafter referred to as a measured room temperature). This is compared with a desired room temperature (set room temperature) set by the user, and when the measured room temperature is low and does not reach the set room temperature, the duty ratio of the PWM signal is increased according to these differences, and Of the switch element is increased to increase the rotation speed of the electric motor 14.

At this time, the DC voltage Ed of the capacitor 5,
That is, the DC power supply voltage of the inverter 13 is fixed at 150 V, and the switch element of the inverter 13 is performing a chopper operation.
Even if the measured room temperature does not reach the set room temperature even if it becomes 0%, the microcomputer 15 switches the drive signal changeover switch 22 to the contact B side to drive the constant voltage Ei to the inverter drive as described in the above step 117. By supplying the current to the circuit 16, the duty ratio of the switch element of the inverter 13 is maintained at 100%, and at the same time, the voltage command changeover switch 21 is switched to the contact A side so that the PWM is switched.
The voltage Ed2 ′ obtained by smoothing the signal with the LPF 25 is supplied to the voltage comparator 7 as the voltage Ed ′. Then, the duty ratio of the PWM signal is reduced so that the voltage Ed 'becomes smaller than the reference voltage Eo.

As a result, the duty ratio of the switch element 6 becomes
When the DC voltage Ed of the capacitor 5 is 150 V, the duty ratio becomes larger than the duty ratio. As a result, the DC voltage Ed of the capacitor 5 gradually increases from 150 V, and the rotation speed of the electric motor 14 increases. At the same time, the room temperature further increases, and the measured room temperature reaches the set room temperature.

As described above, when the input AC power supply voltage is 100
In the case of V, by switching each switch, it becomes possible to output a drive control signal for the switch element 6 and the inverter 13 from the microcomputer 15 through a single port,
When the duty ratio of the switch element of the inverter 13 is 100%, a command voltage Ed2 ′ (PWM signal) for changing the DC voltage Ed as the power supply voltage of the inverter 13 is output. A control voltage (PWM signal) for driving the inverter 13 is output. And
In each of these cases, a signal input to the drive circuit 16 of the inverter 13 is a predetermined constant voltage for driving the switch element of the inverter 13 at a duty ratio of 100%, or an inverter drive signal from a single port of the microcomputer 15. (PWM signal) and means for switching and outputting (drive signal changeover switch 22), the above-mentioned control becomes possible even if a relatively low-function and inexpensive microcomputer is used as the microcomputer 15, and inexpensive. Products can be supplied.

When the duty ratio reaches 100%, the control of the DC voltage Ed obtained by the capacitor 5 controls the rotation speed of the motor 14.

Therefore, when the ON / OFF duty ratio of the switch element of the inverter 13 is less than 100%, the DC voltage Ed1 'is compared with a constant reference voltage Eo.
Since the switching speed of the electric motor 14 is controlled by turning on and off the switching element of the inverter 13 at an arbitrary duty ratio after setting the constant value to a comparatively low arbitrary value of about 150 V, the inverter 13 or the electric motor 14 is controlled. And the efficiency can be improved.

Further, when the duty ratio of the switch element of the inverter 13 is 100%, an arbitrary command voltage Ed2 'is switched instead of the DC voltage Ed1' and supplied to the voltage comparator 7 for comparison with the reference voltage Eo. Then, the command voltage Ed2 ′ is changed in accordance with the desired rotation speed of the electric motor 14, and thus the chopper is not performed by the inverter 13 and the DC voltage value Ed is controlled to be large or small. Since the height is controlled, chopper loss in the inverter 13 can be reduced.

By such a rotation control, it is possible to reduce the switching loss in the inverter 13 and to improve the efficiency by driving the motor 14 with the low DC voltage by the inverter, thereby achieving higher efficiency.

FIG. 4 is a diagram showing a comparison between the motor speed and the efficiency of this embodiment and a conventional air conditioner under a certain motor load, where A indicates that the input AC power supply voltage is one.
B shows the characteristics of this embodiment that performs the above operation when the voltage is 00 V, and B denotes a conventional air conditioner in which the DC power supply voltage of the inverter is kept constant, or 200 V in the input AC voltage.
The characteristics of this embodiment performing the above operation when V is shown, respectively.

In the figure, an air conditioner (hereinafter referred to as a known air conditioner) in which the DC power supply voltage of the inverter is kept constant at, for example, 300 V and the number of rotations of the motor is controlled by controlling the duty ratio of the chopper of the inverter. ), The efficiency is represented by a characteristic B with respect to the rotational speed n (rpm) of the motor.
It changes like The reason that the efficiency increases with an increase in the rotation speed n is that the hysteresis loss of the electric motor is reduced by increasing the duty ratio of the chopper of the inverter.

On the other hand, when the input AC power supply voltage is 100 V
As described above, when the duty ratio of the chopper of the inverter is less than 100%, the DC power supply voltage of the inverter becomes 1
The rotation speed of the motor is controlled by controlling the duty ratio of the chopper with the inverter at a constant 50 V, and the duty ratio becomes 10%.
0%, an embodiment in which the number of rotations of the motor is controlled by controlling the DC power supply voltage of the inverter (hereinafter, an embodiment)
With an input of 100 V), the efficiency of the motor changes as shown by a characteristic A with respect to the rotation speed n of the motor, and is considerably higher than the efficiency B of the conventional air conditioner.

Here, the region n ₁ is a region where the duty ratio of the chopper is less than 100% in the inverter in the embodiment of the input of 100 V, and the region n ₂ is a region where the duty ratio of the chopper is in the inverter in the embodiment of the input of 100 V. 100% area, and the maximum possible rotation of the motor at the boundary between the areas n ₁ and n ₂ , that is, when the inverter is chopper-driven at a DC power supply voltage of 150 V with respect to the motor load. The number is 4000 (rpm). In any case, the DC power supply voltage of the inverter is 300
At V, when the energization of the switch element of the inverter is 100%, the rotation speed of the electric motor is 9000 (rpm).

In the known air conditioner, the DC power supply voltage of the inverter is set to 300 V in the entire region including the regions n ₁ and n ₂ ,
The rotation speed of the electric motor is controlled by controlling the duty ratio of the switch element of the inverter. In contrast, input 100
In embodiments and V, in the region n _1, a DC power supply voltage of the inverter as a half of 150V for 300 V, the control of the duty ratio of the inverter switching elements, speed control of the motor is performed. Therefore, the lower the DC power supply voltage of the inverter, the higher the efficiency of the 100 V input embodiment.

Further, in the region n ₂ , in the embodiment of the input of 100 V, the duty ratio of the switch element of the inverter is set to 100
%, The chopper is not performed by the inverter, and the rotation speed of the motor is controlled by controlling the DC power supply voltage of the inverter. For this reason, the efficiency is substantially constant, but as shown by the characteristic A, the efficiency is higher than that of the known air conditioner because the inverter does not substantially perform the chopper.

It should be noted that the number of rotations of the electric motor is almost 9000 (r
pm), in the 100V input embodiment:
Inverter duty ratio is 100% and its DC power supply voltage is 3
00V, which is the same state as when the duty ratio of the inverter in the known air conditioner becomes 100%, so that the characteristics A and B match.

In the first embodiment shown in FIG.
The power converter is controlled according to the above-described procedure.
By properly setting the resistance values of each of the above, even when the input AC power supply voltage is 100 V or 200 V, any DC voltage Ed can be obtained, and the high power factor with few harmonics can be obtained. It becomes a power converter.

At this time, the detected output voltage of the input current detector 23 is supplied to the microcomputer 15, and when the detected output voltage exceeds a predetermined value, the microcomputer 15 outputs a drive trigger signal VT for the switch element 6, and outputs the signal. Start switching operation. Therefore, when the supply current is large, a stable high power factor can be obtained.

For example, when a resistor is used as the load current detector 9 and a current signal Vi is to be obtained from a voltage generated between both ends, a voltage sufficient for controlling a small current is generated. It is necessary to set the resistance value to be large. In this case, when the load current increases, the power consumed by the load current detector 9 composed of this resistor increases, resulting in an increase in loss. Therefore, in order to reduce this loss, the resistance value of the input current detector 23 should be reduced as much as possible, and in order to prevent unstable operation with respect to the minute detection voltage at the time of low load current. When the detected output value is smaller than the predetermined value, the driving of the switch element 6 is prohibited. In this way, unstable operation at low input current is avoided and loss at high input is reduced. In addition, when the input current is low, by preventing the chopper operation of the switch element 6 from being performed, the loss can be reduced and the noise can be reduced.

In FIG. 1, the active converter block 24 includes an active converter driving unit, 1
A circuit switching unit of 00V / 200V, a switching unit of an inverter drive signal and a DC voltage command signal, and the like are divided into blocks and integrated on the same substrate.

By constructing the active converter block 24 on a substrate independent of other circuits, as shown in FIG. 5, a power factor improving circuit composed entirely of passive elements such as a capacitor 26, a reactor 27 and a diode 28 is provided. Q can be replaced, and the peripheral circuit board including the microcomputer 15 and the like can be shared.

FIG. 6 shows an air conditioner using a circuit constituted by passive elements as shown in FIG. 5 and an active element, wherein the number of revolutions of the motor is controlled in accordance with the DC power supply voltage of the inverter. FIG. 2 is a diagram showing a comparison of the output range of the motor with the first embodiment shown in FIG. 1, wherein the horizontal axis represents the number of revolutions N of the motor, and the vertical axis represents the load torque T,
The output W of the motor is approximately proportional to N × T.

In the figure, the input current is limited by the capacity of the household breaker (for example, 20 A), and the maximum input to the air conditioner (= input power supply voltage × input current × power factor)
Is limited. In the air conditioner using the circuit shown in FIG. 5, since the power factor is about 90%, the input limit range (that is, the range in which the output of the electric motor can be taken) is in a region below the Y line.
Is regulated. On the other hand, in the first embodiment,
As described above, since the power factor is improved to almost 100%, the area below the X-rays becomes the input restriction range, and the electric motor is compared with the air conditioner using the circuit shown in FIG. The effective power applied to the power supply is increased by about 10%. In particular, when the load torque of the electric motor is large, the electric motor is limited by the input restriction range.

When the rotational speed of the motor increases, the maximum output range of the motor is limited by the DC power supply voltage Ed of the inverter. Since the motor generates an induced voltage by its own rotation, the current does not flow at a low DC voltage, and the rotation speed does not increase more than a certain value even with no load. In particular, an electric motor that can achieve high efficiency in a low-speed region where the operation is performed most often for a long time has a large induced voltage generated at the same rotation speed, and therefore the rotation speed that can be driven by the same DC voltage tends to be lower. Therefore, it can only rectify and smooth the AC power supply voltage. For example, in the configuration as shown in FIG. 5, there is a trade-off problem that the more efficient the motor, the higher the rotational speed and the lower the maximum output.

In the air conditioner using the circuit shown in FIG. 5, the DC power supply voltage Ed is, for example, from approximately 230 V to a maximum of approximately 280 V, and the limit range when Ed = 230 V is indicated by a line Y ′. I have. The output of the motor can be obtained only in the range on the left side of the Y 'line. On the other hand, in the first embodiment, the DC power supply voltage Ed
Is 300 V in the above example and 150 V
To 300 V, and the maximum limited range at 300 V is indicated by an X 'line. This means that the output range of the motor has been expanded, and that a high maximum output can be obtained while using an efficient motor.
The above-mentioned disadvantage can be improved.

FIG. 7 is a block diagram showing a second embodiment of the air conditioner according to the present invention. Reference numeral 30 denotes an AC power supply voltage detector, and portions corresponding to those in FIG. The description of the operation will be omitted.

In the figure, the point different from the first embodiment shown in FIG. 1 is that an AC power supply voltage detector 30 is provided, and the input AC power supply voltage from the AC power supply 1 is detected by the AC power supply voltage detection. The microcomputer 30 detects the input AC power supply voltage based on the detection output signal Vs'. Then, according to the determination result, the DC voltage switch 18
The switching of the synchronization signal switch 20 is controlled in the same manner as in the first embodiment.

In the first and second embodiments, the determination of the input AC power supply voltage and the output of the control signal are performed by the microcomputer 15.
However, it is obvious that the same effect can be obtained by using a hardware circuit.

FIG. 8 is a block diagram showing a third embodiment of the air conditioner according to the present invention, in which 31 is an AC / DC changeover switch, 32 is a DC power supply, and portions corresponding to FIG. And duplicate explanations are omitted.

In this figure, in the third embodiment,
DC power supply 32 such as a solar power supply instead of rectifier 2
(For example, about 150 V), so that either the DC power supply voltage EA from now on or the rectified voltage Es from the rectifier 2 can be selected by the AC / DC switch 31. It is possible to function as a circuit.

When the DC power supply 32 is selected, the microcomputer 15 reduces the DC voltage of the capacitor 5 to 16 in FIG.
The same operation as when it is determined to be 0 V or less (step 102) is performed. Therefore, in the third embodiment, the electric motor 14 can be driven by the low-voltage DC power supply 32.

When a DC power supply such as a solar cell is connected to the power supply side of the reactor 3, even if the DC power supply voltage fluctuates,
It can be stabilized to a desired DC voltage Ed. As a result, connection can be made regardless of the power supply voltage fluctuation of a solar cell or the like and the type of DC power supply (solar cell, storage battery, fuel cell, etc.). In addition, the collector of the switch element 6,
Similar effects can be obtained even when a DC power supply such as a solar cell is connected between the emitters via a diode and a reactor.

If the output DC voltage EA of the DC power supply 32 is higher than the DC voltage Ed obtained by full-wave rectification of the input AC power supply voltage from the AC power supply 1, the AC / DC changeover switch 31
, And the motor control may be performed by the DC power supply 32, or the circuit may be switched in advance by manual operation.

When a DC power supply such as a solar cell is connected to the smoothing capacitor 5 via a diode (not shown), if the output voltage of the DC power supply has reached the desired DC voltage, Power is supplied from the DC power supply, and when the desired DC voltage is not reached, power is supplied from the AC power supply to boost the voltage to the desired DC voltage, thereby turning on and off the switching element of the inverter 13. By controlling the rotation speed of the electric motor 14 by using the AC power source, the commercial AC power source can be used in combination with the DC power source, and power can be saved.

FIG. 9 is a block diagram showing a fourth embodiment of an air conditioner according to the present invention. The same reference numerals are given to portions corresponding to those in FIG. 1 and duplicate description will be omitted.

In the figure, the difference from the first embodiment shown in FIG. 1 is that the microcomputer 15 also has the functions of a DC voltage switch 18, a voltage command switch 21 and a drive signal switch 22. And an output port to the inverter drive circuit 16 and an output port to the voltage comparator 7 are provided independently.

As in the first embodiment, the microcomputer 15 switches the synchronization signal changeover switch 20 according to the input power supply voltage.
, And A / D-converts and reads the divided DC voltage Ed1 of the DC voltage Ed in the microcomputer 15. Then, according to the value of the divided DC voltage Ed1, a DC voltage Ed ′ corresponding to the input AC power supply voltage of 100V or the input AC power supply voltage of 200V is obtained, and the DC voltage obtained by integration is obtained by the DC voltage Ed. A PWM signal having a duty ratio such that 'is formed and output. This PW
The M signal is smoothed by the low-pass filter 25 and the DC voltage E
d ′, which is supplied to the voltage comparator 7.

The operation by the software corresponds to the operation of the DC voltage E in the smoothing capacitor 5 in the first embodiment and the like.
The switching operation of the DC voltage changeover switch 18, the voltage command changeover switch 21, and the drive signal changeover switch 22 is controlled in accordance with d to select one of the divided voltages Ed1 and Ed2. As compared with the case of the operation by such hardware, the configuration is simplified and the same control operation can be performed.

When the duty ratio of the switch element of the inverter 13 is 100%, the signal supplied from the microcomputer 15 to the inverter drive unit 16 is a constant voltage Ei having a predetermined value, and the duty ratio is less than 100%. In this case, the control voltage (PWM signal) for driving the inverter 13 is used.

Also, as the DC voltage Ed 'supplied to the voltage comparator 7, when the above-mentioned duty ratio is 100%,
A command voltage Ed2 ′ (PWM signal) for changing the DC voltage Ed is set. This PWM signal is smoothed by the low-pass filter 25 to be a DC voltage Ed ′, which is supplied to the voltage comparator 7.

On the other hand, when the duty ratio is less than 100%, the microcomputer 15 obtains a predetermined low DC voltage Ed 'from the divided DC voltage Ed2 (or the DC voltage Ed), integrates the low DC voltage Ed' and integrates the low DC voltage Ed '. PWM of duty ratio which becomes voltage Ed '
Generate and output a signal. This PWM signal is smoothed by the low-pass filter 25 to become a DC voltage Ed ′, which is supplied to the voltage comparator 7.

Therefore, the peripheral circuit such as a switch for switching the voltage is provided with the same function in the microcomputer 15, so that the number of parts is greatly reduced particularly when multi-stage switching is required. And the routing of wiring to each switch is reduced,
The reliability is greatly improved, including the improvement in noise resistance.

In the embodiment shown in FIGS. 7 to 9, similarly to the embodiment shown in FIG. 1, the operation described in FIGS. 2 and 3 is performed, and the effects described in FIGS. It goes without saying that it can be obtained.

As in the above embodiment, when the control for driving the motor by increasing the DC voltage to an arbitrary value is performed and the determination of the power supply voltage is performed based on the DC voltage after the rectification and smoothing, the operation time is reduced. There is not always a correlation between the DC voltage and the AC power supply voltage. Therefore, the voltage applied during the previous operation needs to be sufficiently discharged before the determination.

Normally, there is no problem because the battery is discharged by a discharge resistor or the like. However, in the case of a failure in the discharge system or a momentary interruption of the power supply during operation, the DC voltage remains high due to the previous operation state. It is also possible.

For example, when the power supply voltage is momentarily interrupted during operation, the microcomputer 15 is reset and attempts to determine the power supply voltage again. In this case, in the short time when the power supply is momentarily interrupted, the electric charge charged in the smoothing capacitor is not sufficiently discharged. For example, when the operation is performed at Ed = 300 V, the AC power supply determination result is high. There is a possibility that the voltage may be erroneously recognized as if it were a voltage.

As a method of detecting an AC voltage, generally, an inductive transformer is used to lower the power supply voltage, and
There is also a method of rectifying and smoothing the secondary output and determining it as a DC voltage value, but while it is easy to obtain an output proportional to the power supply voltage,
There are problems such as an increase in the cost of the induction transformer itself, an increase in loss due to energization of the transformer, and a securing of a mounting space.

Therefore, at the time of reset, the electric charge stored in the smoothing capacitor is discharged in advance before the voltage judgment is performed while making use of the judgment based on the DC voltage of the smoothing capacitor which is advantageous for cost, power saving and space saving. A fifth embodiment of the present invention that prevents erroneous determination of the AC power supply voltage will be described.

FIG. 10 is a block diagram showing a fifth embodiment of the air conditioner according to the present invention, in which 33 is a rectifier for rectifying an AC power supply voltage, and 34 is a smoothing capacitor for smoothing the voltage rectified by the rectifier 33. , 35 are the smoothing capacitors 3
4, a transformer circuit for converting the DC voltage smoothed into a plurality of arbitrary types of voltages; 36, a power relay for connecting the AC power supply 1 and the rectifier 2; 37, a connection configuration of the rectifier 33 for full-wave rectification or double voltage This is a switching relay for switching to the rectification method, and portions corresponding to those in FIG. 3 are denoted by the same reference numerals, and redundant description is omitted.

Next, a control method according to the fifth embodiment will be described with reference to FIG.

First, when the AC power supply 1 is turned on (step 200), the microcomputer 15 is set to an initial state, whereby the microcomputer 15 sets the DC voltage switch 18 and the synchronization signal switch 20 to the contact A side, and The command changeover switch 21 is closed to the contact B side, and the drive signal changeover switch 22 is closed to the contact A side. As a result, the DC voltage switch 18 selects the DC voltage Ed2, and the synchronous signal switch 20 selects the sine wave synchronous signal Es2 (step 201).

Here, the power relay 36 is de-energized, and the DC voltage E is determined before the input AC voltage is determined.
It is determined whether or not d is a sufficiently low DC voltage Eth (for example, 100 V) that does not hinder this determination (step 202).

If Ed> Eth, the power relay 36 remains de-energized, and turns on any one phase of the upper arm of the inverter 13 and any phase of the lower arm different from the phase of this upper arm. Thus, the electric charge of the smoothing capacitor 5 is discharged through the electric motor 14 (step 203).

At this time, the switch element (not shown) of the upper arm of inverter 13 is turned on at an arbitrary duty ratio,
Is turned off, and the current supplied to the motor 14 at that time is:
It comprises a chopper current I1 and a return current I2.

Here, the current supplied from the smoothing capacitor 5 is the chopper current I1, and even if a charge remains in the smoothing capacitor 5, the current is discharged according to the following equation. Ed (t) = Ed (0) × exp ｛(− D ₀ ² × t) /
(R × C)｝ where, Ed (0): initial DC voltage D ₀ : arbitrary duty t: elapsed time R: motor winding resistance C: smoothing capacitor capacity, and this discharging operation is performed until Ed <Eth. Continue.

As described above, as means for discharging the smoothing capacitor 5, the inverter 13 and the motor 1 already provided are provided.
By using No. 4, it is not necessary to newly add a discharge resistance or the like, and this is also an advantageous configuration for cost reduction and size reduction.

When the smoothing capacitor 5 has been discharged in advance, it is not necessary to perform the above operation.

Next, when the power relay 36 is turned on (step 204), the charge corresponding to the AC power supply voltage is charged from the AC power supply 1 to the smoothing capacitor 5 via the rectifier 2 and the reactor 3.

After waiting for the time required to generate a DC voltage corresponding to the AC power supply voltage, the microcomputer 15 detects the divided voltage Ed1 of the DC voltage Ed of the capacitor 5 (step 101). Based on the detected voltage value of the DC voltage Ed1, Ed = Ed1 × (R4 + R5 + R6) / (R5 + R6), if the DC voltage Ed is higher than 160 V, for example (step 102), it is determined that the input AC power supply voltage is 200V. If, for example, the voltage is lower than 160 V (step 102), it is determined that the input AC power supply voltage is 100V.

The subsequent operation is the same as that described in the flowchart of FIG.

As described above, by discharging the electric charge stored in the smoothing capacitor 5 before the determination of the AC power supply voltage, it is possible to prevent the erroneous determination of the AC power supply voltage.

In FIG. 10, the switching relay 37 is turned on or off in accordance with which power supply voltage category the input AC power supply voltage belongs to, so that the configuration of the rectifier 33 is changed so that the smoothing is performed. Capacitor 34
Thus, either the full-wave rectifier or the voltage doubler rectifier can be selected. For example, if the input AC power supply voltage is 100
If it is determined to be V, the switching relay 37 is turned on to make the rectifier 33 a voltage doubler rectifier, and if it is determined to be 100 V, the switching relay 37 is turned off to make the rectifier 33 a full-wave rectifier. . The DC voltage obtained by the smoothing capacitor 34 is appropriately converted by the transformer circuit 35, and the voltage comparator 7, the multiplier 8, the load current detector 9, the current comparator 10, the oscillator 11, the drive circuit 12, the microcomputer 15, the inverter drive Circuit 16, switches 18, 20, 21, and 2
2. The DC power supply voltage of the trigger element 19, the input current detector 23 and the like can be obtained.

By performing the above control, it is possible to suppress a change in input voltage to the control power supply, and to improve line regulation. Therefore, by adding the switching relay 37, it is possible to easily obtain a stable output voltage independent of the input of the control power supply.

As described above, according to the above embodiment, it is possible to detect the supplied AC power supply voltage and arbitrarily control the DC voltage set value. For example, when an AC power supply voltage of 100 V is supplied, an inverter is controlled at an arbitrary DC voltage of 150 V or more, rather than performing a chopper operation of the inverter at an arbitrary duty ratio with a constant DC voltage of about 300 V to control the rotation speed. Since the loss can be reduced by controlling without a chopper having a 100% duty ratio, switching the set value of the DC power supply voltage in accordance with the supplied AC power supply voltage is effective for increasing the efficiency.

Further, according to the above-described embodiment, it is possible to arbitrarily control the set value of the sine wave synchronizing signal. A small power converter can be provided.

Further, according to the above-described embodiment, the detection of the supply current and the trigger of the operation of the switch element are as follows.
When the supply current is small, it is not necessary to provide a high power factor, so that unstable operation of control at the time of low current supply, extra loss, noise, and the like can be eliminated.

Further, according to the above-described embodiment, it is possible to provide a motor drive device whose performance and function do not change regardless of whether the power supply voltage is 100 V or 200 V. Models do not diversify,
By integrating models, it is possible to improve productivity and reduce costs.

Further, according to the above embodiment, the block including the switch element is made independent on the same substrate, so that it can be easily replaced with a power factor correction circuit constituted by conventional passive elements, and the control circuit can be shared. And the development of models becomes easier, and the early provision of new products becomes easier.

Further, according to the above embodiment, it is also possible to connect a DC power supply such as a solar power supply. In this case, the DC voltage can be varied and changed by the next-stage switching element.
Since the voltage can be boosted, it is possible to drive the motor with a relatively low DC voltage.

Furthermore, according to the above-described embodiment, peripheral circuits such as a switch group for switching control signals can be incorporated in the microcomputer, so that the number of parts can be greatly reduced, and the switch group can be reduced. Since the routing of the wiring to the wiring is also reduced, it is possible to improve the reliability including the improvement of the noise resistance.

Further, according to the above embodiment, the chopper operation at the predetermined low power supply voltage of the inverter allows
In addition to controlling the rotation speed of the motor, when the duty ratio in the chopper operation of the inverter reaches 100%, the rotation speed of the motor is controlled by controlling the power supply voltage of the inverter. Loss can be greatly reduced, and the efficiency can be greatly increased.

Further, according to the above-described embodiment, since the supplied AC power supply voltage is detected as a DC voltage to determine the AC power supply voltage, it is not necessary to add a circuit for detecting the AC power supply. This configuration is advantageous in that cost and power consumption and size can be reduced while eliminating the need for an increase in the substrate mounting area while eliminating the increase in power consumption.

Further, at the time of resetting, before the voltage judgment is performed, the electric charge stored in the smoothing capacitor is discharged in advance, thereby making it possible to prevent erroneous judgment of the AC power supply voltage. This is particularly effective when the electric motor is driven by increasing the DC voltage to an arbitrary value as in the configuration circuit of the above embodiment.

Further, with the configuration of the above-described embodiment, the use of the inverter and the motor already provided as means for discharging the smoothing capacitor eliminates the need to particularly add a new discharge resistor or the like. This is a configuration advantageous for cost reduction and miniaturization.

Further, the configuration of the converter for the control power supply in the above embodiment can be selected according to which of the power supply voltage categories the AC power supply voltage belongs to, so that the control power supply does not easily depend on the input of the control power supply. It is possible to obtain a reduced output voltage.

[0138]

As described above, according to the present invention,
Even if the input AC power supply voltage of the different input AC power supply voltage is shared and connected, when the input AC power supply voltage determined by the determination unit is low, the output DC voltage is held at a low predetermined value in a low rotation speed region of the motor. Since the rotational speed of the motor is controlled by changing the duty ratio of the switch element of the inverter, the loss in the inverter or the motor can be reduced, and the efficiency can be improved.

Further, according to the present invention, even when commonly connected to AC power supplies having different input AC power supply voltages, when the input AC power supply voltage determined by the determination means is low, the motor operates in a low rotational speed region. The rotation speed control method of the motor is switched between the high rotation speed region and the output DC voltage is maintained at a low predetermined value in the low rotation speed region of the motor, and the duty ratio of the switch element of the inverter is changed to reduce the rotation speed of the motor. By controlling the loss of the inverter or the motor, the duty ratio of the switch element of the inverter is maintained at a high predetermined value in a high rotation speed region of the motor, and the output DC voltage is changed to control the rotation speed of the motor. As a result, the switching loss of the inverter can be reduced, and the efficiency of the motor can be improved from a low rotation speed region to a high rotation speed region.

Further, according to the present invention, even if the input AC power supply is shared with AC power supplies of different types of input AC power supply voltage, it can operate with a high power factor and a small number of harmonics. The adverse effect on the side can also be suppressed.

[Brief description of the drawings]

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

FIG. 2 is a flowchart illustrating a control method according to the first embodiment illustrated in FIG. 1;

FIG. 3 is a diagram for explaining the control method shown in FIG. 2 when the input AC power supply voltage is 100 V in the first embodiment shown in FIG. 1;

FIG. 4 is a diagram showing the effect of the control method described in FIG. 3 in comparison with a conventional example.

FIG. 5 is a block diagram showing an example in which the active filter block of the first embodiment shown in FIG. 1 is replaced.

6 is a diagram showing a comparison between the effects of the first embodiment shown in FIG. 1 and an air conditioner using the circuit shown in FIG. 5;

FIG. 7 is a block diagram showing a second embodiment of the air conditioner according to the present invention.

FIG. 8 is a block diagram showing a third embodiment of the air conditioner according to the present invention.

FIG. 9 is a block diagram showing a fourth embodiment of the air conditioner according to the present invention.

FIG. 10 is a block diagram showing a fifth embodiment of the air conditioner according to the present invention.

FIG. 11 is a flowchart illustrating a control method according to the fifth embodiment illustrated in FIG. 10;

FIG. 12 is a circuit configuration diagram of a motor drive device in a conventional air conditioner.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 AC power supply 2 Rectifier 3 Reactor 4 Diode 5 Capacitor 6 Switching element 7 Voltage comparator 8 Multiplier 9 Load current detector 10 Current comparator 11 Oscillator 12 Drive circuit 13 Inverter 14 Motor 15 Microcomputer 16 Inverter drive circuit 18 DC voltage signal switching Switch 19 Trigger element 20 Synchronous signal changeover switch 21 Voltage command changeover switch 22 Drive signal changeover switch 23 Supply current detector 24 Active converter block 25 Low pass filter 26 Power supply capacitor 27 Reactor 28 Diode 29 Room temperature sensor 30 AC power supply voltage detector 31 AC / DC Changeover switch 32 DC power supply 33 Rectifier 34 Capacitor 35 Control power supply circuit 36 Power relay 37 Switching relay Q Power factor improvement circuit

──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor, Yuhachi Takakura 800, Tomita, Ohira-machi, Ohira-machi, Shimotsuga-gun, Tochigi Prefecture Inside the Cooling Division, Hitachi, Ltd. No. 1 Hitachi, Ltd. Hitachi Research Laboratory (72) Inventor Yukio Kawabata 1-1-1, Omikacho, Hitachi City, Ibaraki Prefecture Inside Hitachi Research Laboratory Hitachi Research Laboratory (72) Inventor Hiroshi Shinozaki Odamachi, Shimotsuga-gun, Tochigi Prefecture 800 Address Within the Cooling Division, Hitachi, Ltd. (58) Field surveyed (Int. Cl. ⁷ , DB name) F24F 11/02 102

Claims (5)

(57) [Claims] 1. An air conditioner having a motor drive device for driving a compressor, wherein the motor drive device is connected to an AC power supply, and rectifies and boosts an input AC power supply voltage to output a DC voltage. An inverter that uses the output DC voltage of the power converter as a power supply voltage, a control device that controls the power converter and the inverter, and a motor that is driven by the inverter. The inverter has a switch element that is turned on and off so as to change the output DC voltage, the inverter has a switch element that is turned on and off, and the control device determines a type of the input AC power supply voltage. When the input AC power supply voltage determined by the determination means is low, the output DC voltage is maintained at a low predetermined value in a low rotation speed region of the motor, and the input is maintained. When the input AC power supply voltage is high, the output DC voltage is held at a high predetermined value in a low rotation speed region of the motor when the input AC power supply voltage is high. Control means for controlling the number of revolutions of the electric motor by changing the duty ratio of a switch element of the inverter. 2. An air conditioner having a motor drive device for driving a compressor, wherein the motor drive device is connected to an AC power supply, and rectifies and boosts an input AC power supply voltage to output a DC voltage. An inverter that uses the output DC voltage of the power converter as a power supply voltage; a control device that controls the power converter and the inverter; a motor that is driven by the inverter; And a room temperature sensor that provides the detection signal to the power conversion device. The power conversion device has switch means that is turned on and off so as to change the output DC voltage, and the inverter is a switch element that is turned on and off. The control device includes: a determination unit configured to determine a type of the input AC power supply voltage; comparing the measured room temperature detected by the room temperature sensor with a set temperature; Means for changing the duty ratio of the switch element of the motor, and when the input AC power supply voltage determined by the determination means is low, the output DC voltage is held at a low predetermined value in a low rotation speed region of the motor, and The rotation speed of the motor is controlled by changing the duty ratio of the switch element of the inverter, and when the input AC power supply voltage is high, the output DC voltage is held at a high predetermined value in a low rotation speed region of the motor and the motor is controlled. Control means for controlling the number of revolutions of the electric motor by changing the duty ratio of a switch element of the inverter. 3. An air conditioner having a motor drive device for driving a compressor, wherein the motor drive device is connected to an AC power supply, and rectifies and boosts an input AC power supply voltage to output a DC voltage. An inverter that uses the output DC voltage of the power converter as a power supply voltage, a control device that controls the power converter and the inverter, and a motor that is driven by the inverter. The inverter has a switch element that is turned on and off so as to change the output DC voltage, the inverter has a switch element that is turned on and off, and the control device determines a type of the input AC power supply voltage. When the input AC power supply voltage determined by the determination means is low, the output DC voltage is maintained at a low predetermined value in a low rotation speed region of the motor, and the input is maintained. The rotation speed of the motor is controlled by changing the duty ratio of the switch element of the motor, and the duty ratio of the switch element of the inverter is maintained at a high predetermined value in the high rotation speed region of the motor, and the output DC voltage is reduced. When the input AC power supply voltage is high, the output DC voltage is held at a high predetermined value in a low rotation speed region of the motor, and the duty ratio of the switch element of the inverter is controlled. Control means for controlling the number of revolutions of the electric motor by changing the air conditioner. 4. The control device according to claim 3, wherein when the input AC power supply voltage determined by the determination means is low, the control device holds the output DC voltage at a low predetermined value in a low rotation speed region of the motor. At the same time, the rotation speed of the motor is controlled by changing the duty ratio of the switch element of the inverter, and the duty ratio of the switch element of the inverter is set to 100 in the high rotation speed region of the motor.
%. The air conditioner further comprising control means for controlling the number of revolutions of the electric motor by changing the output DC voltage while maintaining the output DC voltage at%. 5. An air conditioner having a motor drive device for driving a compressor, wherein the motor drive device is connected to an AC power supply, and rectifies and boosts an input AC power supply voltage to output a DC voltage. An inverter that uses the output DC voltage of the power converter as a power supply voltage, a control device that controls the power converter and the inverter, and a motor that is driven by the inverter. A capacitor for smoothing a rectified voltage obtained by the rectifier and supplying a DC voltage to the inverter, a switch connected between the rectifier and the capacitor, and controlled to be turned on and off by a drive signal; Power factor improving signal generating means for generating a signal for controlling the switch means so that the load current of the power converter follows the waveform of the rectified voltage. The inverter includes a switch element that is controlled to be turned on and off. The control device includes: a determination unit configured to determine a type of the input AC power supply voltage; and a control unit that determines a type of the input AC power supply voltage determined by the determination unit. Setting means for selectively setting the control value of the power factor improvement signal generating means, and when the input AC power supply voltage determined by the determining means is low, the output DC voltage is reduced in a low rotational speed region of the motor. The motor control is performed by changing the duty ratio of the switch element of the inverter while maintaining the output DC voltage. When the input AC power supply voltage is high, the output DC voltage is increased in a low rotation speed region of the motor. Control means for controlling the number of revolutions of the electric motor by changing the duty ratio of the switch element of the inverter while keeping the value at a predetermined value.