JPH11332286A - Control device of air conditioning equipment - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce a switching loss at an inverter and an eddy current loss in a motor, by detecting the total current of step-up and step-down means, and performing the inverter control of a DC voltage from the step-up means and supplying it to an electric motor. SOLUTION: An AC voltage from an AC power supply 1 is converted to a DC voltage by a diode bridge 3, and the DC voltage is stepped down by a first switching element 4 and a first diode 5 as step-down means. Then, the output is boosted by a coil 6, a second switching element 7, a second diode 8, and an electrolytic capacitor 9 as boosting means. The DC voltage for performing the step-up/down is detected by a DC voltage detection resistors 10a and 10b, and is inputted to a step-up/down control part 16. On the other hand, a DC voltage from the boosting means is subjected to inverter control by an inverter control part 14 via a power transistor module 12 and is supplied to an electric motor 13.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a control device for an air conditioner used in an air conditioner.

[0002]

2. Description of the Related Art Heretofore, a control device for an air conditioner of this type is disclosed in Japanese Patent Application Laid-Open No. 9-266694.

Hereinafter, a control device of the air conditioner will be described with reference to FIG. As shown in the figure, an AC power supply 101 is converted into a DC voltage by a converter unit 110, and the converted DC voltage is controlled by a control signal from a microcomputer 112 by a drive circuit 107 by an inverter circuit 1.
At 04, the voltage is converted to an AC voltage and applied to the motor 105 of the compressor, and the compressor is inverter-controlled. At this time, the microcomputer 112 controls the switching element 110a of the converter unit 110 at the time of high power and outputs a control signal Sc for driving and controlling the switching element 110a at the time of low power according to the output frequency of the inverter control or the rotation speed of the motor 105. Output to converter control circuit 111. Converter control circuit 111 starts control of switching element 110a in accordance with the control signal to make the input current waveform a sine wave, reduces harmonics, and stops control of switching element 110a to stop the switching element 110a.
The power loss due to 10a is reduced.

[0004]

In such a conventional air conditioner control device, there is a control restriction that the converter output is equal to or higher than the power supply voltage.
At 00V, it is about 300V. Therefore, in order to reduce the voltage below this voltage, it is necessary to perform PWM control to lower the equivalent voltage. In this PWM control, the switching loss of the switching element in the inverter unit and the eddy current loss in the motor increase, and There is a problem that noise due to frequency is generated, and it is required to reduce these losses and noise.

[0005] Further, due to recent environmental problems, more energy-saving equipment is desired. SUMMARY OF THE INVENTION The present invention solves such a conventional problem, and can reduce switching loss in an inverter section, eddy current loss in a motor, reduce noise, and control air conditioners that can save energy. It is intended to provide a device.

[0006]

In order to achieve the above object, a control device for an air conditioner of the present invention detects an AC voltage by an AC voltage detecting means for detecting an AC voltage, and converts the AC voltage by a rectifying means. The output is stepped down by the step-down means, the voltage from the step-down means is stepped up by the step-up means,
A desired DC output voltage is obtained by detecting a DC output voltage from the boosting means, and a total current of the step-down means and the boosting means is detected. Countermeasures against harmonics on the
The DC voltage from the booster is controlled by an inverter and supplied to the motor.

According to the present invention, there is provided an air conditioner control device capable of reducing switching noise in an inverter section and eddy current loss in a motor and reducing noise.

Another means is to provide a short-circuit means in parallel with the step-down means. According to the present invention, it is possible to obtain a control device for an air conditioner that eliminates a loss in the switching element of the step-down unit at the time of high power and saves energy.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention provides an AC voltage detecting means for detecting an AC voltage, a rectifying means for converting the AC voltage to a DC voltage, a step-down means for stepping down an output from the rectifying means, Boosting means for boosting the voltage from the means;
DC voltage detecting means for detecting a DC voltage from the boosting means, current detecting means for detecting the total current of the step-down means and the boosting means, and an inverter for inverting the DC voltage from the boosting means and supplying the voltage to the motor And a control device for an air conditioner comprising an electric motor connected to the inverter means.
(Pulse Amplitude Modulati
on) control (hereinafter abbreviated as PAM control)
The switching loss in the inverter unit and the eddy current loss in the motor during the M control can be reduced, and the noise can be reduced.

Further, a short-circuit means is provided to eliminate a loss in the step-down switching element, and has an effect that power consumption at the time of large power can be further reduced.

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

[0012]

(Embodiment 1) As shown in FIG.
Voltage detection resistors 2a, 2b for detecting the AC voltage from
The DC voltage is converted into a DC voltage by a diode bridge 3 as a rectifier for rectifying an AC voltage from the AC power supply 1, and the DC voltage is stepped down by a first switching element 4 and a first diode 5 as a step-down unit. Then, this output is boosted by the coil 6, the second switching element 7, the second diode 8, and the electrolytic capacitor 9 as boosting means. The step-up / step-down (P
AM control) is applied to the DC voltage detection resistor 10
a and 10b are input to the step-up / step-down controller 16. The total current by the step-up / step-down is detected by the current detecting resistor 11 and is also input to the step-up / step-down control unit 16. The step-up / step-down control unit 16 controls the first switching element 4 in the step-down unit and the second switching element 7 in the step-up unit in synchronization with the input from the AC voltage detection resistors 2a and 2b, The current is made a sine wave to take measures against power supply harmonics.

On the other hand, step-up / step-down (PAM control) is performed by the power transistor module 12 as an inverter means.
The variable speed control of the motor 13 is performed by changing the frequency of the obtained DC voltage by the inverter control unit 14 and the CPU 15.

The CPU 15 controls and controls the inverter control unit 14 and the step-up / step-down control unit 16. With the above configuration, first, the buck-boost controller 1
In step 6, the required DC voltage is generated by PAM control. At low power, the voltage rectified from the AC power supply 1 is stepped down. At high power, the voltage rectified from the AC power supply 1 is stepped up. The power transistor module 12 is driven to change the speed of the motor 13.

Although the IGBT is used as the switching element of the step-down means and the step-up means, an FET, a power transistor, or the like may be used, and there is no difference in operation and effect.

Although the power transistor module is used as the inverter means, a module such as an FET or IGBT may be used, or six power transistors, FETs or IGBTs may be used. Makes no difference.

Although a resistor is used as the current detecting means, a current transformer or the like may be used, and there is no difference in the operation and effect.

Although a resistor is used as the AC voltage detecting means, a transformer or the like may be used, so that there is no difference in operation and effect.

(Embodiment 2) Referring to FIG.
16 is the same as that in FIG.

First switching element 4 as step-down means
A relay 17 is connected in parallel between the emitter and the collector as short-circuit means so that the first switching element 4 can be short-circuited.

According to the above configuration, when the step-down operation becomes unnecessary at the time of high power, the emitter 17 and the collector of the first switching element 4 are short-circuited by the relay 17 so that the loss in the first switching element 4 can be eliminated. .

Although a relay is used as the short-circuit means,
Other low-loss semiconductors, such as FETs, may be used, and there is no difference in the operation and effect.

[0023]

As is clear from the above embodiments, according to the present invention, the PAM control is performed from the time of low power to the time of high power, so that the switching loss in the inverter unit during the PWM control and the eddy in the motor are reduced. It is possible to provide a control device for an air conditioner that has an effect of reducing current loss and reducing noise.

Further, it is possible to provide an air conditioner control device which has an effect of reducing power consumption at the time of large power.

[Brief description of the drawings]

FIG. 1 is a circuit diagram of a control device for an air conditioner according to Embodiment 1 of the present invention.

FIG. 2 is a circuit diagram of a control device of the air conditioner according to the second embodiment.

FIG. 3 is a circuit diagram of a conventional air conditioner control device.

[Explanation of symbols]

 2a AC voltage detecting resistor 2b AC voltage detecting resistor 3 Diode bridge 4 First switching element 5 First diode 6 Coil 7 Second switching element 8 Second diode 9 Electrolytic capacitor 10a DC voltage detecting resistor 10b DC voltage detecting resistor 11 Current detecting resistor 12 Power transistor module 13 Motor 17 Relay

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁶ Identification code FI H02M 7/48 H02M 7/48 F 7/5387 7/5387 Z

Claims (2)

[Claims] An AC voltage detecting means for detecting an AC voltage;
Rectifying means for converting the AC voltage into a DC voltage, step-down means for stepping down the output from the rectifying means, step-up means for stepping up the voltage from the step-down means, and DC for detecting the DC voltage from the step-up means. Voltage detection means, current detection means for detecting the total current of the step-down means and the step-up means,
A control device for an air conditioner, comprising: inverter means for inverting the DC voltage from the boosting means and supplying the DC voltage to the motor; and a motor connected to the inverter means. 2. The control device for an air conditioner according to claim 1, further comprising a short-circuit means in parallel with the step-down means.