JP2007259622A - Inverter controller and compressor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an inverter controller for suppressing beat sounds, even if a capacitor for rectification has a very small capacitance. <P>SOLUTION: The inverter controller is provided with a rectifying circuit 2 for inputting an AC power supply 1 and converting it into DC power; an inverter circuit 3 for converting the DC power into AC power for driving the motor 4 at an arbitrary frequency; a frequency control means 5 for controlling the frequency of the inverter circuit 3; a target frequency input means 6 for inputting the target operating frequency of the motor 4; a power supply frequency detecting means 7 for detecting the power supply frequency of the power supply 1; and a motor-frequency detecting means 8 for detecting the frequency of the motor 4. The frequency control means 5 outputs a drive signal to the inverter circuit 3, based on the inputted target operating frequency, the detected frequency of the motor 4, the detected power supply frequency and doubled frequency thereof. The beat sounds of the motor 4 are significantly suppressed by the frequency control means 5 for temporally changing the operating frequency. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an inverter control device and a compressor used for an air conditioner or the like.

  In an inverter control device used in a conventional air conditioner or the like, the operating frequency of the compressor built in the air conditioner is an integral multiple of the power supply frequency (50 Hz or 60 Hz × n (n = 1, 2, 3,... When the frequency is close to)), there are problems such as unstable compressor operation and abnormal noise and vibration. Therefore, when the operation frequency is close to an integral multiple of the power supply frequency, for example, if the power supply frequency is 50 Hz, the range of 50 × n ± 1 Hz is set as the operation prohibition frequency, and the operation is performed avoiding that frequency.

  Therefore, even when the operation frequency is in the range of the operation prohibition frequency, it is substantially equivalent to the operation at the operation frequency itself, and can be operated at a frequency close to an integer multiple of the power supply frequency. An inverter control device for a harmonic machine has been proposed (see, for example, Patent Document 1).

  Hereinafter, an inverter control apparatus using this method will be described with reference to FIGS.

  FIG. 3 is a block diagram of the air conditioner disclosed in Patent Document 1.

  In FIG. 3, AC power from the AC power source 1 is converted into DC power by the rectifier circuit 2, and the converted DC power is smoothed by the capacitor 10 and converted into AC power of an arbitrary frequency by the inverter circuit 3. This AC power is supplied to the motor 4, and the compressor 11 is driven by the motor 4.

FIG. 4 is a graph showing frequencies actually operated by the inverter control device of the air conditioner when the operation request frequency f _C is 50 Hz. As shown in FIG. 4, the power source frequency is set to 50 Hz, the operation is limited to the limit of the operation-prohibited area every fixed time T, and the first operation frequency f ₁ is set to 50 + 2 = 52 Hz for the first operation time T1. in 50 - 2 = 48 Hz as second operating frequency f ₂ is operated only the second operating time T2, then operated at 52Hz in the first operating frequency by a first operating time T1, ...... and thereafter continued alternately If the first and second times T1 and T2 are set as T1 = T2, it is substantially equivalent to driving at an average value of 50 Hz.

Thus, two frequencies and two corresponding operation times are determined in advance according to the value of the operation prohibition frequency, and when there is an operation request at the operation prohibition frequency, each of the two predetermined frequencies is used. By alternately operating for the corresponding time, the operation is substantially equivalent to the case of operation at the operation frequency itself, and the operation at the operation inhibition frequency can be avoided.
JP-A-7-31193

However, in the configuration of the above conventional inverter control device, when the rectifying capacitor 10 connected to the input side of the inverter circuit 3 has a very small capacity, the frequency is twice the power supply frequency (100 Hz or 50 Hz if 50 Hz). DC voltage is almost 0 at 120Hz)
Since it drops to V, when it is operated alternately at a frequency twice this power frequency, an operating frequency slightly higher than the prohibited frequency and an operating frequency slightly lower than the prohibited frequency, an integer multiple of the operating frequency slightly higher than the prohibited frequency, and Due to the difference in frequency with an integer multiple of the operating frequency slightly lower than the forbidden frequency, there was a problem that a roaring sound was generated in the motor 4 and propagated to the compressor 11.

  The present invention solves the above-described conventional problems, and can drive a motor for driving a compressor or the like at a frequency substantially close to an integral multiple of the power supply frequency, and the rectifying capacitor has an extremely small capacity. Even if it exists, it aims at providing the inverter control apparatus which can suppress the beat sound of a motor.

  In order to solve the above-described conventional problems, an inverter control device according to the present invention includes a rectifier circuit that receives AC power as input and converts the DC power into DC power, and an inverter that converts the DC power into AC power having an arbitrary frequency for driving a motor. Circuit, frequency control means for controlling the frequency of the inverter circuit, target frequency input means for inputting a target operating frequency of the motor, power supply frequency detection means for detecting the power supply frequency of the AC power supply, and frequency of the motor Motor frequency detection means for detecting the target frequency, the frequency control means, the target operating frequency input by the target frequency input means, the motor frequency detected by the motor frequency detection means, and the power supply frequency detection Based on the power frequency input by the means and twice the power frequency. Outputs drive signals to, by the power supply frequency and double frequency thereof, and temporally changing the operation frequency by the frequency control means, it is possible to greatly suppress the beat sound of the motor to be driven.

  The compressor according to the present invention includes a motor driven by the inverter control device according to claim 1 or 2 and suppresses the beat sound of the motor. Therefore, the compressor and the air in which the compressor is incorporated Operation noise and vibration of equipment such as a harmonic machine are greatly reduced.

  The inverter control device of the present invention can drive a motor that drives a compressor or the like at a frequency substantially close to an integral multiple of the power supply frequency, and even if the rectifying capacitor has a very small capacity, It is possible to suppress the beat sound of the motor.

  A first invention includes a rectifier circuit that receives AC power as an input and converts it into DC power, an inverter circuit that converts the DC power into AC power having an arbitrary frequency for driving a motor, and a frequency that controls the frequency of the inverter circuit Control means, target frequency input means for inputting a target operating frequency of the motor, power supply frequency detection means for detecting the power supply frequency of the AC power supply, and motor frequency detection means for detecting the frequency of the motor, The frequency control means includes a target operating frequency input by the target frequency input means, a frequency of the motor detected by the motor frequency detection means, a power supply frequency input by the power supply frequency detection means, and a power supply frequency thereof. A drive signal is output to the inverter circuit based on twice the frequency. The frequency doubler, by temporally changing the frequency using the frequency control means can be significantly suppressed beat sound of the motor to be driven.

In the second invention, in particular, the AC power source in which n times (n is an integer) of the motor frequency detected by the motor frequency detecting means is detected by the power frequency detecting means by the frequency control means of the first invention. When the power frequency is in the vicinity of a value that is twice the power frequency, the operating frequency of the motor has a vertical width, n times the motor frequency, and a value that is twice the AC power frequency. The correction waveform operation frequency that periodically changes within a frequency cycle that is a difference between the motor and the correction waveform operation frequency is n times the motor frequency and the AC power supply even if the correction waveform operation frequency is a different target operation frequency. If the difference between the power frequency and the power frequency is the same, the ratio is the same, so that it is possible to suppress the roaring sound and to easily set the control pattern.

  According to a third aspect of the present invention, a motor driven by the inverter control device according to claim 1 or 2 is incorporated in the compressor, and since the beat sound of the motor is suppressed, the compressor and the motor are incorporated. Operation noise and vibration of equipment such as air conditioners are greatly reduced.

  Embodiments of the present invention will be described below with reference to the drawings. Note that the present invention is not limited to the present embodiment.

(Embodiment 1)
FIG. 1 is a block diagram of an inverter control apparatus according to the first embodiment of the present invention.

  In FIG. 1, the inverter control device in the present embodiment uses a diode bridge 2 a, a rectifier circuit 2 that receives a single-phase AC power supply 1 and converts it into DC power, and converts the DC power into AC power having an arbitrary frequency. An inverter circuit 3 for converting and driving the motor 4, a small capacity reactor 9 connected to the AC input side or DC output side of the diode bridge 2a, and an extremely small capacity connected to the DC output side of the diode bridge 2a The capacitor 10 and the frequency control means 5 for controlling the frequency of the inverter circuit 3 are configured.

  The frequency control means 5 receives the operation request frequency from the target frequency input means 6, outputs the motor frequency detection means for detecting the frequency of the motor 4, the power supply frequency of the AC power supply 1 detected by the power supply frequency detection means 7, and A drive signal is output to the inverter circuit 3 based on a frequency twice the power supply frequency.

  Reference numeral 11 denotes a compressor driven by the motor 4.

  Here, in the inverter control device for a conventional air conditioner, when the power supply frequency is 50 Hz, the frequency that is an integral multiple of the power supply frequency ± 1 Hz is set as the prohibited frequency, and when the indicated frequency is 49 Hz, By alternately operating a frequency slightly higher than the upper limit and a frequency slightly lower than the lower limit of the forbidden frequency, the operation is substantially equivalent to operating at 49 Hz.

  However, if the capacitor 10 connected to the DC output side of the diode bridge 2a has a very small capacity, the voltage between the DC buses of the inverter 3 may pulsate greatly with a period twice the power supply frequency and become zero. . For example, when the power supply frequency is 50 Hz, it may pulsate greatly with a period of 100 Hz that is twice as large, and may become zero.

  As a result, when the motor 4 is operating for a certain period of time at 52 Hz, which is slightly higher than the upper limit of the forbidden frequency, and 48 Hz, which is slightly lower than the lower limit of the forbidden frequency, the power source is 104 Hz which is twice this 52 Hz. The difference between 100 Hz, which is twice the frequency, and the difference between 96 Hz, which is an integral multiple of 48 Hz, and 100 Hz, which is twice the power supply frequency, generate a roaring sound. The beat sound period is both 4 Hz.

  FIG. 2 shows the inverter control apparatus according to the present embodiment, when the operation request frequency input from the target frequency input means 6 is 98 Hz, and when the operation request frequency is 49 Hz, the inverter control apparatus actually operates. It is a graph which shows the time change (correction waveform) of the frequency to be performed.

  First, when the operation request frequency is 98 Hz (operation request frequency 2), the width is vertically centered on 98 Hz, which is the difference between 98 Hz of the motor 4 frequency and 100 Hz which is twice the frequency of the AC power supply. The operation is performed at a correction waveform operation frequency that is periodically changed within a period of 2 Hz.

  The correction waveform is such that the operation time at the half end close to the power supply frequency is longer than the other, and in this embodiment, the amplitude at the half end close to 100 Hz, which is twice the frequency of the AC power supply. Is 0.6 Hz and the half cycle is 0.278 sec, the other amplitude is 1.0 Hz and the half cycle is 0.167 sec, and the operating frequency of the motor 4 is temporally changed.

  Therefore, as shown in FIG. 2, the operating frequency of the motor 4 is operating in the range of 97.0 Hz to 98.6 Hz, and therefore the difference from the frequency of 100 Hz, which is twice the power frequency, is a beat sound. It becomes. The beat sound is 1.4 Hz to 3 Hz and the period is 0.33 sec to 0.71 sec. Therefore, as shown in FIG. Since the operation frequency of the motor 4 is changed more than the beat sound cycle, the beat sound is not generated and the beat sound can be suppressed.

  Here, the amplitude is set to +0.6 Hz, −1.0 Hz, and the period is set to 0.278 sec and 0.167 sec. Of course, this may be another numerical value. Since it changes at the same rate as the increase / decrease centering on 98 Hz, it is substantially equivalent to the case where the motor frequency is operated at 98 Hz.

  Further, when the operation request frequency is 49 Hz (operation request frequency 1), the operation is performed at a correction operation frequency that has a width up and down around 49 Hz and periodically changes. At this time, the generated beat sound is a difference between 98 Hz which is an integral multiple of 49 Hz of the operating frequency of the motor 4 and 100 Hz which is twice the power supply frequency of the AC power supply.

  That is, the same beat sound is obtained as when the operation request frequency is 98 Hz. Therefore, when the correction waveform operation frequency when the operation request frequency is 49 Hz is set to the same ratio as that when the operation request frequency is 98 Hz, it is possible to suppress the beat sound.

  Actually, the amplitude of the half-end on the side close to 50 Hz of the frequency of the AC power supply 1 is 0.3 Hz and the half cycle is 0.278 sec. The other amplitude is 0.5 Hz and the half cycle is 0.167 sec. The operating frequency of this will be changed over time.

  As a result, the operating frequency of the motor 4 operates in the range of 48.5 Hz to 49.3 Hz, as shown in FIG. 2, and therefore the frequency of 97 Hz to 98.6 Hz, which is an integral multiple thereof, and the power source of the AC power supply The difference from 100 Hz, which is twice the frequency, becomes a beat sound. Here, as shown in FIG. 2, since the operating frequency of the motor 4 is changed faster than the roaring sound, the roaring sound can be suppressed.

  As described above, even when the operation request frequency is different from 98 Hz and 49 Hz, the difference between the integer multiple of the motor frequency and 100 Hz which is twice the frequency of the AC power supply 1 is the same, that is, the operation request frequency. Is 98 Hz, and when the difference between 98 Hz and 100 Hz is the same as the difference between 98 Hz and 100 Hz, which is an integral multiple of 49 Hz, when the operation request frequency is 49 Hz, the correction waveform operation frequency is set to the same ratio. When the operation request frequency is 49 Hz, the beat sound is generated at 98 Hz, which is a component twice the operation request frequency. Therefore, the amplitude is ½ of the correction waveform operation frequency when the operation request frequency is 98 Hz. Thus, it is possible to suppress a beat sound.

  Therefore, by determining a control pattern for temporally changing the operation frequency of the motor 4 at the operation requested frequency of 98 Hz, a control pattern of 49 Hz is also determined, and the control pattern can be easily determined.

  Moreover, the inverter control apparatus of this invention is applicable to the compressor which operate | moves by driving a motor.

  The inverter control device of the present invention can greatly suppress beat noise, and is not limited to a compressor or an air conditioner incorporating the compressor, but includes a refrigerator, an electric washing machine, and an electric dryer having a motor driven by an inverter. The present invention can be applied to various devices such as a vacuum cleaner, a blower, and a heat pump water heater, and the degree of freedom in designing these devices can be improved.

Block diagram of the inverter control apparatus in Embodiment 1 of the present invention Graph for explaining frequency control of the inverter control device Block diagram of an air conditioner with a built-in inverter control device Graph for explaining frequency control of the inverter control device

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 AC power supply 2 Rectifier circuit 3 Inverter circuit 4 Motor 5 Frequency control means 6 Target frequency input means 7 Power supply frequency detection means 8 Motor frequency detection means 9 Reactor 10 Capacitor 11 Compressor

Claims (3)

A rectifier circuit that receives AC power as input and converts it into DC power, an inverter circuit that converts the DC power into AC power of any frequency that drives the motor, frequency control means that controls the frequency of the inverter circuit, and the motor Target frequency input means for inputting the target operating frequency, power supply frequency detection means for detecting the power supply frequency of the AC power supply, and motor frequency detection means for detecting the frequency of the motor, the frequency control means comprising: Based on the target operation frequency input by the target frequency input means, the frequency of the motor detected by the motor frequency detection means, the power supply frequency input by the power supply frequency detection means and twice the power supply frequency. An inverter control device that outputs a drive signal to the inverter circuit. By the frequency control means, n times the motor frequency detected by the motor frequency detection means (n is an integer) is in the vicinity of a value that is twice the power supply frequency of the AC power supply detected by the power supply frequency detection means. When the operating frequency of the motor has a width in the vertical direction, periodically within a frequency period that is a difference between n times the frequency of the motor and a value that is twice the power frequency of the AC power supply. When the correction waveform operation frequency is changed and the correction waveform operation frequency is a different target operation frequency, the difference between n times the motor frequency and twice the AC power supply frequency is the same. The inverter control device according to claim 1, wherein the same ratio is set. A compressor having a built-in motor driven by the inverter control device according to claim 1.

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