JP4882358B2 - Inverter control device - Google Patents

Description

  The present invention relates to an inverter control device for an air conditioner.

  Conventionally, as an inverter control device used in an air conditioner, an inverter type air conditioner that changes a frequency change rate when the frequency is lowered has been proposed (for example, see Patent Document 1). FIG. 3 is a configuration diagram of a conventional inverter type air conditioner. Hereinafter, a conventional inverter air conditioner control device will be described with reference to FIG.

  A compressor primary current detection device 12 for detecting a primary current (single phase) on the power source side of the compressor 11 is provided at a place connected to the outdoor microcomputer 13. With the above configuration, the remote controller set temperature set by the remote controller 14 and the indoor suction temperature detected by the indoor suction temperature sensor 16 provided in the indoor unit 15 are input to the indoor microcomputer 17 during normal heating operation. The indoor microcomputer 17 determines the indoor required capacity and transmits it to the outdoor microcomputer 13 in the outdoor unit 18.

  In the outdoor microcomputer 13, if the primary current of the compressor 11 detected by the compressor primary current detection device 12 is equal to or less than a value determined for each frequency (hereinafter referred to as a current control value), the indoor required capacity is achieved. The target operation frequency is determined, and if the current operation frequency is less than a specific frequency (for example, 52 Hz, hereinafter referred to as a specific frequency) and the target operation frequency is a value that decreases from the current operation frequency. The frequency signal is output to the transistor module 19 so as to slowly fall from the current operating frequency to the target operating frequency (for example, 0.1 Hz / sec), and the transistor module 19 is converted to a direct current by a converter unit (not shown). The current is switched, and a pseudo three-phase current having a target operation frequency is output to the compressor 11. If the target operating frequency is equal to or higher than a specific frequency (for example, 52 Hz) or increases from the current operating frequency, the speed of change from the current operating frequency to the target operating frequency is increased (for example, 2.4 Hz / sec). If the primary current of the compressor 11 detected by the compressor primary current detection device 12 is equal to or higher than the current control value, the operating frequency is lowered until the primary current becomes equal to or lower than the current control value. This is performed in accordance with the rules for the changing speed of the operating frequency as described above.

Here, for example, if the indoor suction temperature approaches the remote controller set temperature under the condition that the secondary current of the compressor becomes high, such as during heating overload operation, the indoor required capacity decreases and the operation frequency decreases. According to the above-mentioned rules, the operating frequency change speed decreases slowly when the frequency is low, the voltage decreases slowly, and the torque of the compressor 11 also decreases slowly. By slowly lowering the operating frequency, the discharge pressure also decreases slowly, but because the way of lowering is originally delayed by the operation of the refrigeration cycle, it does not depend on the way of lowering the operating frequency, and it is compressed even at a point where the operating frequency is low. The machine 11 does not run out of torque and can prevent a large current due to breakdown. Further, since the voltage is originally high when descending from a high operating frequency, the torque of the compressor 11 is unlikely to be insufficient, and the voltage is also increased when the operating frequency is increased. The rate of change of the air is fast (eg, 2.4 Hz / sec) to prevent indoor air hunting due to overshooting of the indoor blow-out temperature (the room air will not rise and fall with respect to the remote control set temperature). be able to.
Japanese Patent Laid-Open No. 9-264618

  However, in the above-described conventional configuration, if the smoothing capacitor for rectification connected to the input side of the inverter has an extremely small capacity, when the operating frequency of the compressor is changed at an arbitrary change speed, the power supply frequency of 2 Since the DC voltage drops to almost 0 V at double the frequency (100 Hz for 50 Hz, 120 Hz for 60 Hz), the difference between the frequency twice this power supply frequency and the integer multiple of the compressor frequency There was a problem that a roaring sound was generated.

  SUMMARY OF THE INVENTION The present invention solves the above-described conventional problems, and an object thereof is to provide an inverter control device that can suppress a beat noise of a compressor even if a smoothing capacitor for rectification has a very small capacity. .

  In order to solve the above-described conventional problems, an inverter control device according to the present invention is driven by an AC voltage, a rectifier circuit that receives an AC power supply, an inverter circuit that converts a DC voltage into a pseudo AC voltage having an arbitrary frequency, and the AC voltage. Motor, frequency control means for controlling the frequency of the inverter circuit, target operating frequency input means for inputting the target operating frequency of the compressor, power frequency detecting means for detecting the frequency of the AC power supply, Motor frequency detection means for detecting a frequency, wherein the frequency control means is a frequency of the AC power detected by the power supply frequency detection means, a target operating frequency input by the target operating frequency input means, and the motor frequency A drive signal is output to the inverter circuit based on the frequency of the motor detected by the detecting means. Is shall.

  Accordingly, the frequency can be temporally changed by the frequency control means based on the output of the power supply frequency and the motor frequency.

  Even if the smoothing capacitor for rectification has a very small capacity, it is possible to provide an inverter control device that can suppress the beat sound of the compressor.

An inverter control device according to a first aspect of the present invention converts a DC voltage into a pseudo AC voltage having an arbitrary frequency, a rectifier circuit that receives an AC power supply, a small-capacitance capacitor connected to the DC output side of the rectifier circuit, and the like. Inverter circuit, motor driven by AC voltage, frequency control means for controlling frequency of said inverter circuit, target operating frequency input means for inputting target operating frequency of compressor, and frequency of said AC power source are detected A power frequency detecting means; and a motor frequency detecting means for detecting the frequency of the motor. The frequency control means is input by the AC power source frequency detected by the power frequency detecting means and the target operating frequency input means. On the basis of the target operating frequency and the motor frequency detected by the motor frequency detecting means. And it outputs a motion signal, wherein n times the motor frequency to be detected by the motor frequency detection means (n = 1,2,3 ···) 2 is the frequency of the AC power detected by the power supply frequency detecting means when in the vicinity of the fold to become a value, said frequency control means has a width operating frequency up and down to drive the motor, and controls so that a correction operation frequency time periodically changes, the operating frequency When changing, the operation frequency is changed step by step, and it moves on the line that connects the same phase to the operation frequency of the next step within the time of one cycle of the correction operation frequency corresponding to the operation frequency of each step. Then it is what. Thereby , based on the output of a power supply frequency and a motor frequency, a frequency can be temporally changed with a frequency control means. Then, it is possible to suppress a beat sound generated when the operating frequency is changed.

In the second invention, particularly in the inverter control device of the first invention, n times (n = 1, 2, 3...) Of the motor frequency detected by the motor frequency detecting means is detected by the power supply frequency detecting means. Within a frequency cycle that is a difference between n times the motor frequency and a value that is twice the frequency of the AC power supply, in the vicinity of a value that is twice the frequency of the AC power supply to be performed. By moving the operating frequency, it is possible to suppress a beat sound generated when the operating frequency is changed.

The third invention is a compressor using the inverter control device of the first or second invention.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. Note that the present invention is not limited to the embodiments.

(Embodiment 1)
FIG. 1 is a block diagram of an inverter control apparatus according to the first embodiment of the present invention.
FIG. 1 shows a rectifier circuit 2 that receives a single-phase AC power source 1 and converts it into DC power, an inverter circuit 3 that converts DC power into AC power of an arbitrary frequency, and a motor 4 driven by this AC power. The compressor 11 and the rectifier circuit 2 use a diode bridge, and are connected to a small capacity reactor 9 of 2 mH or less connected to the AC input side or DC output side of the diode bridge, and to the DC output side of the diode bridge. The capacitor 10 has a very small capacity of 0.4 μF to 100 μF and the frequency control means 5 that controls the frequency of the inverter circuit 3. The frequency control means 5 receives the operation request frequency from the target operation frequency input means 6, and based on the outputs of the power supply frequency detection means 7 for determining the frequency of the AC power supply and the motor frequency detection means 8 for detecting the frequency of the motor. The drive signal is output to the inverter circuit 3.

  Here, when the power supply frequency is 50 Hz and the capacitor 10 connected to the DC output side of the diode bridge has a very small capacity, the voltage between the DC buses of the inverter 3 pulsates with a period twice the power supply frequency, May be 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 compressor is operating at 48 Hz, a difference between 96 Hz, which is twice this 48 Hz, and 100 Hz, which is twice the power supply frequency, becomes a roaring sound. The beat sound period is 4 Hz. Next, when the operating frequency of the compressor is 49 Hz, a difference between 98 Hz, which is twice, and 100 Hz, which is twice the power collection frequency, that is, a 2 Hz beat sound is generated.

  Next, FIG. 2A shows the inverter control apparatus according to the first embodiment of the present invention, where the operation request frequency input from the target operation frequency input means 6 is 49 Hz, the inverter control apparatus It is a graph which shows the time change (correction waveform) of the frequency actually operated. In FIG. 2A, since the operation request frequency is 49 Hz, the temporal change in the frequency of the compressor is changed into a sine wave shape around 49 Hz. The amplitude is ± 0.5 Hz and the period is 0.5 sec. Here, the amplitude is set to 0.5 Hz, and the period is set to 0.5 sec. Of course, this may be another numerical value. Similarly, FIG. 2B shows a temporal change in frequency when the operation request frequency is 48 Hz. FIG. 2B shows a change in the frequency of the compressor with a sinusoidal shape centered on 48 Hz. The amplitude is ± 0.5 Hz and the period is 0.25 sec. FIG.2 (c) shows the time change of the frequency in case an operation request frequency is 47 Hz.

  As shown in FIG. 2 (a), FIG. 2 (b), and FIG. 2 (c), when the operating frequency of the compressor is changed faster than the beat period, no beat sound is generated and the beat sound is suppressed. Can do.

Here, the temporal change in frequency at each operating frequency is as described above, but the rate of change when the operating frequency is raised or lowered will be described. When the change speed is constant, a beat sound may occur at a certain frequency, which is slower than the beat sound cycle. Accordingly, FIG. 2 (a), FIG. 2 (b), on a line connecting the one cycle points of the correction waveform of the temporal change of the frequency in each frequency shown in FIG. 2 (c) (line), or this line When the operating frequency is changed at a faster change speed, it is possible to suppress the beat sound that occurs when the operating frequency increases and decreases. In addition, when making the change speed faster than the said line , you may be a linear change. Moreover, the inverter control apparatus of this invention is applicable to the air conditioner carrying a compressor.

  The inverter control device of the present invention can be applied to an inverter control device that drives a motor using an inverter. For example, a refrigerator equipped with an inverter, an electric washing machine, an electric dryer, an electric vacuum cleaner, a blower, a heat pump water heater, and the like. In any product, it is possible to suppress the beat sound generated in the inverter control device, and to improve the degree of freedom in product design.

The block diagram which shows the inverter control apparatus in Embodiment 1 of this invention. Control diagram showing frequency control of inverter control device in same embodiment Block diagram explaining a conventional inverter type air conditioner

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Single-phase alternating current power supply 2 Rectifier circuit 3 Inverter circuit 4 Motor 5 Frequency control means 6 Target operation 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 an AC power supply, a small-capacitance capacitor connected to the DC output side of the rectifier circuit, an inverter circuit that converts a DC voltage into a pseudo AC voltage of an arbitrary frequency, and an AC voltage drive A motor, frequency control means for controlling the frequency of the inverter circuit, target operating frequency input means for inputting a target operating frequency of the compressor, power supply frequency detecting means for detecting the frequency of the AC power supply, and frequency of the motor The frequency control means detects the frequency of the AC power source detected by the power supply frequency detection means, the target operating frequency input by the target operating frequency input means, and the motor frequency detection Based on the frequency of the motor detected by the means, a drive signal shall be output to the inverter circuit ,
It is in the vicinity of which results in a doubling of the value of the frequency of the AC power n times the motor frequency to be detected by the motor frequency detecting means (n = 1,2,3 ···) is detected by the power supply frequency detecting means when the frequency control means has a width operating frequency up and down to drive the motor, and controls so that a correction operation frequency time periodically changes, when the change of the operation frequency, stepwise the operation shall change the frequency, within one period of the correction operation frequency corresponding to the operating frequency of each stage time, the next stage of the driving characteristics and to Louis inverter to move on a line defined by connecting the same phases to the frequency Control device. When n times (n = 1, 2, 3,...) Of the motor frequency detected by the motor frequency detecting means is in the vicinity of a value that is twice the frequency of the AC power source detected by the power frequency detecting means. 2. The inverter according to claim 1, wherein the operating frequency is moved stepwise within a frequency cycle that is a difference between n times the motor frequency and a value that is twice the frequency of the AC power supply. Control device. Compressor using an inverter control device according to claim 1 or 2.

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