JPH1023789A - Vibration control device for inverter driven air conditioner - Google Patents

Abstract

PROBLEM TO BE SOLVED: To restrain hunting with high accuracy at a low cost, by detecting the fluctuation of a peak value from the outputted signal of a motor current detection part for checking if hunting occurs, and adjusting outputted voltage. SOLUTION: Hunting is detected by an AC part hunting discrimination part 4 from a motor current detection part 3 consisting of a current sensor for detecting motor current running through a compressor 2 and a change in current obtained by the motor current detection part 3. An output voltage command value is changed from the output of an AC part hunting discrimination part 4, and a PWM pulse is calculated to drive a reverse conveter 1. It is thus possible to restrain hunting with high accuracy at a low cost, by a simple method of detecting hunting easily with the current sensor and changing voltage.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an anti-vibration control for an air conditioner driven by an inverter, and more particularly, to a variable speed driving of an air conditioner in which V / F constant control is performed by a pulse width modulation type inverter. It relates to vibration prevention control.

[0002]

2. Description of the Related Art When a compressor of an air conditioner is driven by a voltage type inverter, when the load of the compressor is light and the inertia is low, vibration occurs in a specific frequency band, and the operation of the air conditioner is reduced. There was a problem that caused trouble.

This phenomenon is called a turbulence phenomenon, and includes a time constant of an induction motor built in a compressor, a carrier frequency of a pulse width modulation type inverter, a dead time for preventing a vertical short circuit of a power element, an output frequency of the inverter, and the like. It is thought that factors such as the ratio of the output voltage and the natural frequency of the mechanical system are complicatedly entangled. When this turbulent phenomenon occurs, the output current of the inverter is changed to a fundamental wave as shown in FIG. And a vibration is generated.

By the way, when the frequency of the inverter coincides with the natural frequency of the non-drive system (the main body of the compressor and the piping system connected to the compressor) during the above-mentioned turbulence, a large vibration is generated by resonance, There has been a problem that the operation cannot be continued or a joint of a piping system connected to the compressor is broken by vibration.

As an apparatus for suppressing abnormal vibration of a motor when this unstable phenomenon occurs, for example, Japanese Patent Publication No. 53-27807.
There is known an apparatus described in Japanese Patent Application Laid-Open Publication No. H10-26095. This detects an amount proportional to the electric power, introduces it to a bandpass filter, and loads the signal obtained from the filter output as a stabilizing signal for suppressing vibration into a frequency command so as to prevent vibration. It was made.

In the case where the solution cannot be solved by the control method, the following method has been adopted on the induction motor side. (1) The magnetic flux density between the stators is reduced to weaken the electromagnetic vibrating force and reduce vibration. (2) Vibration amplitude is suppressed by strengthening rigidity. (3) The waveform of the output current of the inverter is smoothed by the AC reactor, and the harmonic component of the AC applied to the induction motor is reduced to reduce the vibration.

[0007]

However, Japanese Patent Publication No. Sho 53-2 has attempted to solve the problem by controlling the inverter.
According to the apparatus described in Japanese Patent No. 7807, it is difficult to stabilize the motor properly if the capacity of the motor changes or the number of pole pairs or the electric constant of the motor differs even if the motor has the same capacity. When a certain amount of load is applied, such as when the apparatus is driven, it is difficult to make a distinction between powering and regeneration, so that it is possible under certain conditions, but difficult under certain conditions.

In order to realize such control, the amount of calculation increases, so that a high-speed processing device is required, which leads to an increase in cost. This is a major problem when applied to an air conditioner.

[0009] Next, regarding the induction motor side, the methods (1) and (2) described above are not realistic because the physique and weight of the induction motor are increased, and particularly, the induction motor is built in the compressor. Not applicable to compressors already in use.

The method (3) is not practical if the size and weight of the AC reactor are increased and the AC reactor is enlarged until an effect is obtained.

[0011]

SUMMARY OF THE INVENTION In order to solve this problem, the present invention relates to an air conditioner in which a compressor is driven by an inverter having an inverter which converts direct current into variable frequency alternating current. A motor current detection unit that detects a motor current, an AC unit turbulence determination unit that detects fluctuation of a peak value from an output signal of the motor current detection unit and determines whether turbulence has occurred, and an AC unit turbulence determination unit. It comprises an output voltage change command section for changing the output voltage according to the output signal, and a waveform calculation section for calculating an actual PWM waveform from the output signal of the output voltage change command section and driving the inverter, and detects turbulence. Then, by adjusting the output voltage, turbulence is suppressed.
According to the present invention, it is possible to obtain an effect that high-precision and low-cost turbulence can be suppressed by a simple method of easily detecting turbulence by a current sensor and changing a voltage.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The invention according to claim 1 of the present invention provides an inverter for converting a direct current into an alternating current of a variable frequency, a compressor driven by the inverter, and a flow through the compressor. A motor current detection unit that converts a change in motor current into a change in voltage, and an AC unit turbulence determination unit that detects fluctuation of a peak value from an output signal of the motor current detection unit and determines whether turbulence has occurred. Calculating an actual PWM waveform from an output voltage change command section for changing an output voltage based on an output signal of the AC section turbulence determination section, and an output signal of the output voltage change command section and an output frequency command value, and performing the inverse conversion It is characterized by being composed of a waveform calculation unit that drives the rectifier. The turbulence can be detected with high accuracy and low cost by a simple method of detecting the turbulence easily by the current sensor and changing the voltage. It has the effect of being able to control.

According to a second aspect of the present invention, there is provided an inverter for converting a direct current into an alternating current having a variable frequency, a compressor driven by the inverter, and a change in motor current flowing through the compressor. A motor current detecting unit that converts a voltage change into a voltage change, an AC unit turbulence determining unit that detects fluctuation of a peak value from an output signal of the motor current detecting unit, and determines whether turbulence is occurring, and the AC unit. A carrier frequency change command unit for changing a carrier frequency based on an output signal of the turbulence determination unit, and an actual PWM waveform is calculated from an output signal and an output frequency command value of the carrier frequency change command unit, and the inverter is driven. When the carrier frequency is lowered, the noise increases in the sense of hearing, but the voltage in the region where the voltage cannot be changed is reduced. Also can be obtained an effect in case, it has the effect of suppressing the effect of high precision and inexpensive to hunting can be obtained.

According to a third aspect of the present invention, there is provided an inverter for converting a direct current into an alternating current having a variable frequency, a compressor driven by the inverter, and a DC current flowing through the inverter. A DC section current detection section for converting a change into a voltage change; a pulse shaping section for detecting the positive and negative current densities from an output signal of the DC section current detection section to perform pulse shaping; and a turbulence caused by an output of the pulse shaping section. A DC portion turbulence determining portion for determining whether or not the output has occurred, an output signal of the DC voltage turbulence determining portion, an output voltage change command portion for changing an output voltage, and an output signal and an output of the output voltage change command portion. An actual PWM waveform is calculated from a frequency command value, and is configured by a waveform calculation unit that drives the inverter. In order to determine turbulence based on the direction and density of the current in the DC unit, motor Although compared to accuracy is reduced when determining the hunting by using a current sensor output current,
Since the current sensor becomes unnecessary, there is an effect that the effect of suppressing the turbulence can be obtained at a lower cost.

According to a fourth aspect of the present invention, there is provided an inverter for converting a direct current into an alternating current of a variable frequency, a compressor driven by the inverter, and a DC current flowing through the inverter. A DC section current detection section for converting a change into a voltage change, a pulse shaping section for detecting the density of the positive and negative currents from an output signal of the DC section current detector, and forming a pulse; DC part turbulence determining unit that determines whether or not a turbulence occurs, a carrier frequency change command unit that changes a carrier frequency according to an output signal of the DC part turbulence determination unit, and an output signal and an output of the carrier frequency change command unit. It is characterized by comprising a waveform calculation unit for calculating an actual PWM waveform from a frequency command value and driving the inverter, and determines turbulence based on the direction and density of the current in the DC unit. Therefore, the accuracy of the output current of the motor is lower than that in the case of using a current sensor or the like to judge the turbulence, and when the carrier frequency is lowered, the noise increases in the sense of hearing, but the voltage may be changed. The effect can be obtained even in the case of a region where it is not possible, and the effect of suppressing the turbulence can be obtained at a lower cost because the current sensor becomes unnecessary.

[0016]

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

(Embodiment 1) FIG. 1 shows the configuration of a vibration preventing device for an inverter-driven air conditioner according to Embodiment 1 of the present invention.

As shown in the drawing, the vibration preventing device of the inverter-driven air conditioner of this embodiment comprises an inverter 1 for driving a compressor 2 and a current sensor for detecting a motor current flowing through the compressor 2. A motor current detecting unit 3, an AC unit turbulence judging unit 4 for detecting turbulence from a change in current obtained by the motor current detecting unit 3, and changing an output voltage command value from an output of the AC unit turbulent judging unit 4. An output voltage change command section 5 output to the waveform calculation section 6, and a PWM for driving the inverter 1 based on the output of the output voltage change command section 5 and the output frequency command value
It is configured by a waveform calculation unit 6 that calculates a pulse and outputs it to the inverter 1.

The processing performed by the AC section turbulence judging section 4 will be described with reference to the flowchart of FIG. First, the peak value of the current in the current cycle is detected, and this value is stored in the current peak (step 1).

The difference between the current peak and the past peak is taken, the result obtained by dividing the difference by the current peak is multiplied by 100, this is defined as the current fluctuation rate, and stored in the current fluctuation rate (step 2).

The current peak is stored in the past peak (step 3). If the current fluctuation rate exceeds 10%, it is determined that there is a turbulence, and if it is less than 10%, it is determined that it is normal (step 4).

If it is determined that the tone is normal, 0 is stored in the turbulence flag (step 5). If it is determined that the tone is a tune, 1 is stored in the tune flag (step 6).

The next output voltage change command unit 5 receives the output of the turbulence judging unit 4 and changes the output voltage command value if it is in a turbulent state. The processing of the output voltage change command unit 5 is shown in FIG.
This will be described with reference to the flowchart of FIG.

First, it is checked whether or not the turbulence flag is 1 (step 1). If the turbulence flag is 1, 1 V is added to the output voltage command value, and the result is stored in the output voltage command value (step 2).

If the turbulence flag is 0, the process is terminated without any operation. The waveform calculation unit 6 calculates a required pulse width from the output voltage command value from the output voltage change command unit 5 and the output frequency command value, and drives the inverter 1 based on the result.

(Embodiment 2) FIG. 4 shows the configuration of a vibration preventing device for an inverter-driven air conditioner according to Embodiment 2 of the present invention.

As shown in the figure, the vibration preventing device of the inverter-driven air conditioner of this embodiment comprises an inverter 1 for driving a compressor 2 and a current sensor for detecting a motor current flowing through the compressor 2. A motor current detecting unit 3; an AC unit turbulence determining unit 4 for detecting turbulence from a change in current obtained by the motor current detecting unit 3; A waveform for calculating a PWM pulse for driving the inverter 1 from the output of the carrier frequency change command section 7 and the output of the carrier frequency change command section 7 and the output of the carrier frequency change command section 7 to be output to the inverter 1 The arithmetic unit 8 is configured.

The process performed by the AC section turbulence judging section 4 is the same as that described in the first embodiment. The next carrier frequency change command section 7 receives the output of the AC section turbulence determination section 4 and changes the carrier frequency command value if it is in a turbulent state.

The processing of the carrier frequency change command section 7 will be described with reference to the flowchart of FIG.

First, it is checked whether the turbulence flag is 1 (step 1). If the turbulence flag is 1, 0.5 kHz is subtracted from the carrier frequency command value, and the result is stored in the carrier frequency command value (step 2).

If the turbulence flag is 0, the process ends without doing anything. The waveform calculation unit 8 calculates a required pulse width from the carrier frequency command value from the carrier frequency change command unit 7 and the output frequency command value, and drives the inverter 1 according to the calculation result.

(Embodiment 3) FIG. 6 shows a configuration of a vibration preventing device for an inverter-driven air conditioner according to Embodiment 3 of the present invention.

As shown in the figure, an anti-vibration device for an inverter-driven air conditioner of this embodiment comprises an inverter 1 for driving a compressor 2 and a fixed resistor for detecting a current flowing through the inverter 1. , A pulse shaping section 10 for shaping a change in current obtained by the DC section current detecting section 9 into continuous pulses, and detecting a turbulence from the type of output signal of the pulse shaping section 10. DC part turbulence judging part 11
And an output voltage change command section 5 that changes the output voltage command value from the output of the DC section turbulence determination section 11 and outputs the output voltage command value to the waveform calculation section 6.
And a waveform calculation unit 6 that calculates a PWM pulse for driving the inverter 1 from the output of the output voltage change command unit 5 and the output frequency command value, and outputs the PWM pulse to the inverter 1.

A description will now be given of the current flowing through the inverter 1 when the turbulence occurs. FIG. 7 shows the current at the time of turbulence. In the event of a turbulence, the input current i0
, The powering current (negative current) i1 and the regenerative current (positive current) i2 are alternately repeated in the pulse width modulation cycle or more, and swing in the positive and negative directions.

Therefore, when a period in which the positive side is dominant and a period in which the negative side is dominant appear, it can be determined that a turbulent state exists.

Then, the DC current detector 9 detects the current flowing through the inverter 1 as a voltage using a fixed resistor and outputs the voltage to the pulse generator 10.

Next, in the pulse forming unit 10, i shown in FIG.
8 is detected by an operational amplifier or the like, and its output is pulse-shaped by giving a time constant by an integrating circuit or the like, and an output signal as shown in FIG.

The processing performed by the DC section turbulence judging section 11 will be described with reference to the flowchart of FIG. First, it is determined whether the input signal is a pulse or not (step 1).

In the case of a pulse, it is determined that the tone is a tune, and 1 is stored in the tune flag (step 2). If it is not a pulse, 0 is stored in the turbulence flag (step 3).

The operation of the next output voltage change command unit 5 and the following is as follows.
This is similar to the first embodiment. (Embodiment 4) FIG. 10 shows a configuration of a vibration preventing device for an inverter-driven air conditioner according to Embodiment 4 of the present invention.

As shown in the figure, an anti-vibration device for an inverter-driven air conditioner of this embodiment comprises an inverter 1 for driving a compressor 2 and a fixed resistor for detecting a current flowing through the inverter 1. , A pulse shaping section 10 for shaping a change in current obtained by the DC section current detecting section 9 into continuous pulses, and detecting a turbulence from the type of output signal of the pulse shaping section 10. DC part turbulence judging part 11
A carrier frequency command value that is changed from the output of the DC section turbulence determining unit 11 and is output to the waveform calculation unit 8; and the output of the carrier frequency change command unit 7 and the output frequency command value PWM for driving converter 1
It is configured by a waveform calculation unit 8 that calculates a pulse and outputs it to the inverter 1.

The DC current detector 9 detects the current flowing through the inverter 1 as a voltage using a fixed resistor and outputs the voltage to the pulse generator 10.

Next, the pulse forming section 10 outputs an output signal as shown in FIG.

The operation after the next carrier frequency change command unit 7 is the same as that of the second embodiment.

[0045]

As described above, according to the first aspect of the present invention, the turbulence can be suppressed with high accuracy and at low cost by a simple method of easily detecting the turbulence by the current sensor and changing the voltage. The advantageous effect described above can be obtained.

According to the second aspect of the present invention, in order to easily detect the turbulence by the current sensor and change the carrier frequency, when the carrier frequency is lowered, the noise increases in the sense of hearing, but the voltage increases. The effect can be obtained even in the case of a region in which can not be changed, and an advantageous effect that high-precision and low-cost turbulence can be suppressed by a simple method can be obtained.

According to the third aspect of the present invention, since the turbulence is determined based on the direction and density of the current in the DC section, the output current of the motor is compared with the case where the turbulence is determined using a current sensor or the like. Although the accuracy is reduced, the necessity of the current sensor is eliminated, and the advantageous effect that the tunable can be suppressed at a lower cost can be obtained.

According to the fourth aspect of the present invention, since the turbulence is determined based on the direction and density of the current in the DC section, the output current of the motor is compared with the case where the turbulence is determined using a current sensor or the like. When the carrier frequency is lowered, the noise is increased in terms of audibility, but the effect can be obtained even in a region where the voltage cannot be changed. An advantageous effect that inexpensive turbulence can be suppressed is obtained.

[Brief description of the drawings]

FIG. 1 is a configuration diagram of a first embodiment of the present invention.

FIG. 2 is a flowchart showing a process performed by an AC section upset determination section;

FIG. 3 is a flowchart illustrating a process of an output voltage change command unit;

FIG. 4 is a configuration diagram of a second embodiment of the present invention.

FIG. 5 is a flowchart showing processing of a carrier frequency change command unit;

FIG. 6 is a configuration diagram of a third embodiment of the present invention.

FIG. 7 is a timing chart showing a current component flowing through the inverter at the time of turbulence;

FIG. 8 is a timing chart showing input / output waveforms of a pulse forming unit;

FIG. 9 is a flowchart showing a process performed by a DC portion turbulence determining unit;

FIG. 10 is a configuration diagram of a fourth embodiment of the present invention.

FIG. 11 is a characteristic diagram showing a motor current waveform at the time of turbulence;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Inverter 2 Compressor 3 Motor current detection part 4 AC part turbulence judgment part 5 Output voltage change command part 6 Waveform calculation part 7 Carrier frequency change command part 8 Waveform calculation part 9 DC part current detection part 10 Pulse shaping part 11 DC Part disorder judgment section

Continuing from the front page (72) Inventor Shusaku Watanabe 4-5-2, Takaidahondori, Higashiosaka-shi, Osaka Inside Matsushita Refrigeration Machinery Co., Ltd. (72) Yoshiro Tsuchiyama 1006 Kadoma, Kazuma-shi, Osaka Matsushita Electric Industrial Co. Inside the company (72) Keizo Matsui 1006 Kadoma Kadoma, Kadoma, Osaka Prefecture Inside Matsushita Electric Industrial Co., Ltd. (72) Inventor Yoshiteru Ito 1006 Kadoma Kadoma, Kadoma, Osaka Pref. Matsushita Electric Industrial Co., Ltd. (72) Inventor Yoshioka 1006 Kadoma, Kadoma, Osaka Prefecture Matsushita Electric Industrial Co., Ltd.

Claims (4)

[Claims] 1. An inverter for converting a direct current into a variable frequency alternating current, a compressor driven by the inverter, and a motor current detection for converting a change in motor current flowing through the compressor into a change in voltage. Unit, an AC unit turbulence determining unit that detects fluctuation of the peak value from an output signal of the motor current detecting unit and determines whether or not turbulence has occurred, and an output voltage based on an output signal of the AC unit turbulence determining unit. And an output voltage change command section for changing the output voltage change command section, and a waveform calculation section for calculating an actual PWM waveform from the output frequency command value and driving the inverter. A vibration prevention device for an inverter-driven air conditioner. 2. An inverter for converting a direct current into an alternating current of a variable frequency, a compressor driven by the inverter, and a motor current detection for converting a change in motor current flowing through the compressor into a change in voltage. Unit, an AC unit turbulence determining unit that detects fluctuation of the peak value from an output signal of the motor current detecting unit to determine whether or not turbulence has occurred, and an output signal of the AC unit turbulence determining unit, And a waveform calculator for calculating an actual PWM waveform from an output signal and an output frequency command value of the carrier frequency change command unit and driving the inverter. A vibration prevention device for an inverter-driven air conditioner. 3. An inverter for converting a direct current into an alternating current of a variable frequency, a compressor driven by the inverter, and a DC unit for converting a change in DC current flowing through the inverter into a change in voltage. A current detection unit, a pulse shaping unit that detects the positive and negative current densities from the output signal of the DC unit current detection unit and performs pulse shaping, and a DC that determines whether or not turbulence has occurred due to the output of the pulse shaping unit. A part disorder judgment section,
An output voltage change command section for changing an output voltage based on an output signal of the DC section turbulence determination section, and an actual PWM waveform calculated from an output signal of the output voltage change command section and an output frequency command value, A vibration prevention device for an inverter-driven air conditioner, comprising a waveform calculation unit for driving the air conditioner. 4. An inverter for converting a direct current into a variable frequency alternating current, a compressor driven by the inverter, and a DC unit for converting a change in a DC current flowing through the inverter into a change in a voltage. A current detection unit, a pulse shaping unit that detects the positive and negative current densities from the output signal of the DC unit current detection unit and performs pulse shaping, and a DC that determines whether or not turbulence has occurred due to the output of the pulse shaping unit. A part disorder judgment section,
A carrier frequency change command section for changing a carrier frequency based on an output signal of the DC section turbulence determination section, and an actual PWM waveform calculated from an output signal and an output frequency command value of the carrier frequency change command section, A vibration prevention device for an inverter-driven air conditioner, comprising a waveform calculation unit for driving the air conditioner.