JPH11341879A - Vibration reducing device for airconditioner - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a vibration reducing device for a low-priced airconditioner, which eliminates the need for a detector for detecting a current flowing particularly between a DC power supply and a power converter, by determining running and regeneration for the purpose of control in the secondary side output of a switching power supply, which generates the power for driving IGBT of an inverter normally mounted to an airconditioner including an inverter. SOLUTION: This apparatus is constituted of a power converter 5 for converting a DC power supply 4 to an AC power supply of variable frequency, an induction motor 1 which is controlled in the number of revolutions, a switching power supply 6 for IGBT drive as the power supply of a switching element of the power converter 5, a voltage variation detecting means 13 for detecting hunting output generated in the secondary side output of the switching power supply 6 for driving IGBT, a voltage variation detecting means 16 for extracting hunting element, and a waveform arithmetic means 21 for changing the basic frequency command value depending on such an output. As a result, it is possible to reduce the hunting element generated in a compressor, without the use of a particular detector.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a vibration reducing device for an air conditioner having a control device for controlling a compressor by a PWM type voltage type inverter.

[0002]

2. Description of the Related Art When a compressor is driven with a constant V / F by a PWM inverter, abnormal vibration may occur depending on a carrier frequency, an electric constant of a motor, a state of a load, and the like.

As a control method for suppressing the vibration when the vibration occurs, for example, an apparatus described in Japanese Patent Publication No. 5-28078 is known.

In this method, the polarity of a current flowing between a DC power supply unit and a power converter and its cycle are detected, and the fundamental frequency command value is corrected according to the polarity and the length of the cycle to prevent vibration. It is something to do.

[0005]

However, since it is necessary to judge power running or regeneration depending on the polarity of the current flowing between the DC power supply unit and the power converter, the current flowing between the DC power supply unit and the power converter must be determined. It is necessary to use a non-contact current transformer as a detector. This non-contact current transformer is relatively expensive, and at present it is difficult to apply it to an air conditioner in terms of cost.

SUMMARY OF THE INVENTION The present invention has been made to solve the above problem, and has a secondary side output of a switching power supply for generating a power supply for driving an IGBT of an inverter normally mounted on an air conditioner having the inverter mounted thereon. The present invention provides a vibration reducing device in an inexpensive air conditioner, which eliminates the need for a detector that detects the current flowing between the DC power supply unit and the power converter by performing power control and regenerative determination and control. The purpose is to:

[0007]

In order to achieve this object, a vibration damping device in an air conditioner according to the present invention comprises: a power converter for converting a DC voltage from a DC power supply into an AC power supply having a variable frequency; An induction motor for an air conditioner whose rotation speed is controlled by a converter, an IGBT driving switching power supply for generating a DC voltage for driving an IGBT which is a switching element of a power converter from a DC voltage of a DC power supply, A voltage fluctuation detection unit that detects the feedback output for keeping the output voltage of the IGBT drive switching power supply unit constant, and extracts only the AC component of the voltage fluctuation detection unit, and corresponds to the small and large parts compared to the average voltage The basic variation is determined by the voltage fluctuation detecting section that outputs the changed pulse, and the length and timing of the pulse output by the voltage fluctuation detecting section. Moderated if necessary several command value, it is constituted by a waveform calculation unit for outputting the output to the power converter.

According to the present invention, there is provided a switching power supply for generating a power supply for driving an IGBT of an inverter mounted on an air conditioner usually mounted with an inverter.
Judgment of power running and regeneration based on fluctuations in the output of the secondary side and control are performed, eliminating the need for a detector that detects the current flowing between the DC power supply and the power converter, and reducing vibration in inexpensive air conditioners. The purpose is to provide.

[0009]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention provides a power converter for converting a DC voltage from a DC power supply into an AC power supply having a variable frequency.
An induction motor for an air conditioner whose rotation speed is controlled by the power converter, and a switching power supply for driving an IGBT that generates a DC voltage for driving an IGBT that is a switching element of the power converter from the DC voltage of the DC power supply unit Unit, a voltage fluctuation detecting unit for detecting a feedback output for keeping the output voltage of the IGBT driving switching power supply unit constant, and extracting only an AC component of the voltage fluctuation detecting unit, and a portion smaller than an average voltage. And a voltage fluctuation detecting section that outputs a pulse corresponding to a large portion, and the length and timing of the pulse output by the voltage fluctuation detecting section, adjust the basic frequency command value as necessary, and output the basic frequency command value. And a waveform calculation unit for outputting to the power converter.

By adopting such a configuration, power running and regenerative operation are caused by fluctuations in the secondary side output of a switching power supply that generates a power supply for driving an IGBT of an inverter normally mounted in an air conditioner equipped with an inverter. By making the determination and performing the control, a detector for detecting the current flowing between the DC power supply unit and the power converter is not required, and it is possible to provide an inexpensive vibration reduction device in an air conditioner.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to FIGS.

FIG. 1 is a block diagram of an inverter control device in an air conditioner according to one embodiment of the present invention.

In FIG. 1, a voltage for driving a switching element of a power converter 5 is generated by a switching power supply 6 for driving an IGBT using a DC voltage of a DC power supply 4. FIG. 2 shows a block diagram of the IGBT driving switching power supply unit 6.

A DC voltage is connected to the primary side coil 7, which is switched by a switch element 8 to perform a secondary side coil 9.
To generate a desired voltage. Further, in order to increase the accuracy of the voltage generated on the secondary side, the voltage on the secondary side is compared with the reference voltage by the comparator 10, and the output is input to the pulse generator 11. The pulse generator 11 drives the switch element 8. By applying feedback in this manner, it is possible to keep the output voltage on the secondary side constant.

Therefore, when the turbulence occurs, the information appears on the secondary side output, and the output is input to the voltage fluctuation detecting unit 13.

In the voltage fluctuation detecting section 13, as shown in FIG. 3, the output of the IGBT driving switching power supply section 6 is amplified by an amplifier 14, and then unnecessary frequency components are removed through a low-pass filter 15. Voltage fluctuation detection unit 1
3 will be described with reference to FIG.

FIG. 4 shows a case where a turbulence occurs.
The upper part shows the input voltage of the amplifier 14, and the middle part shows the output of the low-pass filter 15.

The portion of the output of the low-pass filter 15 shown in the middle stage that is higher than the average voltage indicates a regenerative state in which the inverter is being driven by the motor, and the portion lower than the average voltage indicates a powering state in which the inverter is rotating the motor too much. Is shown.

The output of the voltage fluctuation detecting section 13 is input to the voltage fluctuation detecting section 16. In the voltage fluctuation detecting section 16, FIG.
As shown in (1), only the pulsating component is extracted from the output of the voltage fluctuation detecting unit 13 by the capacitor 17, and is pulse-shaped by the comparator 20 and output to the waveform calculating unit 21. The relationship with the voltage fluctuation detecting unit 13 is shown in the lower part of FIG.

In this way, the switching power supply unit 6 for driving the IGBT can be used without requiring a special detector.
It is possible to extract a turbulent component from the secondary-side output.

The output of the voltage fluctuation detector 16 is input to the waveform calculator 21. The operation of the waveform calculator 21 will be described with reference to the flowchart of FIG.

First, it is confirmed whether or not the measurement between the edges of the input pulse from the voltage fluctuation detecting section 16 has been completed (step 1). If the measurement has not been completed, the process proceeds to step S5.

If the measurement has been completed in step 1,
The current input of the waveform calculator 21 is confirmed.

If the measurement in step 1 has been completed at the present time and the input of the waveform calculation unit 21 is Hi, the currently completed inter-edge measurement result is a Low level section. For the same reason, when the input of the waveform calculation unit 21 is Low, the measurement result is a section of the Hi level (Step 2).

If the input pulse is Hi, the measurement result is stored as regeneration data, and the frequency variation during regeneration is calculated according to the relationship in FIG. 7 (step 3).

If the input pulse is Low, the measured data is stored as power running data, and similarly, the frequency fluctuation amount during power running is calculated from the measured pulse time according to the relationship in FIG. 7 (step 4). .

Next, the current state of the input pulse is monitored to detect a falling edge (step 5). Thereby, the switching point between the powering control and the regenerative control is detected.

If a falling edge is detected, the reference command frequency is changed according to the following equation (step 6).

If the reference command frequency = reference command frequency + regenerative frequency variation falling edge has not been detected, a rising edge is detected (step 7).

If a rising edge is detected, the reference command frequency is changed according to the following equation (step 8).

Reference command frequency = reference command frequency−power running frequency fluctuation amount If no rising edge is detected, the process is terminated and the next timing is waited.

The process from the determination of the reference command frequency to the execution of the PWM output is of a general nature, and will not be described.

Further, in the transition from the current frequency to the newly set reference command frequency, acceleration and deceleration are smoothly performed at a certain rate.

By repeating the above processing, the output frequency and voltage of the inverter are increased so as to cancel the condition that the inverter is being rotated by the motor during regeneration, and the inverter is rotating the motor excessively during power running. Therefore, by lowering the output frequency and voltage of the inverter so as to cancel them, the fluctuations in the energy of the DC power supply unit 4 and the power converter 5 are suppressed, and a stable state is produced, and at the same time, the compressor generates Vibration can be reduced.

[0035]

As described above, according to the present invention, the power running is performed by the fluctuation of the secondary side output of the switching power supply which generates the power supply for driving the IGBT of the inverter mounted on the air conditioner usually mounted with the inverter. In addition, by performing the determination and the control of the regeneration, the detector that detects the current flowing between the DC power supply unit and the power converter becomes unnecessary, and it is possible to provide an inexpensive vibration reduction device in an air conditioner.

[Brief description of the drawings]

FIG. 1 is a configuration diagram of an inverter control device according to an embodiment of the present invention.

FIG. 2 is a configuration diagram of an IGBT driving switching power supply unit according to the embodiment.

FIG. 3 is a configuration diagram of a voltage fluctuation detection unit in the embodiment.

FIG. 4 is a timing chart of an input voltage of an amplifier, an output voltage of a low-pass filter, and an output of a voltage fluctuation detecting unit in the embodiment.

FIG. 5 is a configuration diagram of a voltage fluctuation detecting unit in the embodiment.

FIG. 6 is a flowchart illustrating the operation of a waveform calculation unit according to the embodiment.

FIG. 7 is a relationship diagram showing a relationship between a measurement time of an input pulse and a frequency variation amount in the embodiment.

[Explanation of symbols]

 Reference Signs List 4 DC power supply unit 5 Power converter 6 IGBT driving switching power supply unit 13 Voltage fluctuation detection unit 16 Voltage fluctuation detection unit 21 Waveform calculation unit

Claims (1)

[Claims] 1. A power converter for converting a DC voltage from a DC power supply into an AC power supply having a variable frequency, an induction motor for an air conditioner whose rotation speed is controlled by the power converter, and a DC power supply for the DC power supply. An IGBT driving switching power supply unit for generating a DC voltage for driving an IGBT which is a switching element of the power converter from a voltage;
A voltage fluctuation detecting unit for detecting a feedback output for keeping the output voltage of the BT driving switching power supply unit constant, and extracting only an AC component of the voltage fluctuation detecting unit, and extracting a small portion and a large portion as compared with the average voltage. A voltage fluctuation detecting section that outputs a corresponding pulse, and the length and timing of the pulse output by the voltage fluctuation detecting section,
A vibration mitigation device for an air conditioner, comprising: a waveform calculation unit that adjusts a basic frequency command value as needed and outputs the output to the power converter.