Refrigerator Control System

Abstract

To provide a refrigerator control system that can make it difficult to hear driving sound of a compressor, and a refrigerator.SOLUTION: A refrigerator control system controls a driving circuit for driving a compressor provided in a refrigerator. The refrigerator control system comprises a sound information acquisition unit for acquiring sound information related to sound around the refrigerator, a frequency determination unit for determining a carrier frequency for an inverter circuit comprised in the driving circuit on the basis of the sound information acquired by the sound information acquisition unit, and an inverter control unit for controlling the inverter circuit on the basis of the carrier frequency determined by the frequency determination unit.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a refrigerator control system. [Background technology]

[0002] Conventionally, refrigerators equipped with a compressor driven by inverter control have been disclosed (for example, see Patent Document 1). The compressor includes a motor and compresses a refrigerant to produce a high-temperature, high-pressure gas refrigerant. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2017-32211 A Summary of the Invention [Problem to be solved by the invention]

[0004] Inverter control is a method of controlling the motor's rotation speed with high precision by modulating the motor's drive voltage at high speed with a carrier frequency. Generally, the carrier frequency is often set within the human audible frequency range. The sound of this carrier frequency may resonate with the compressor or parts inside the refrigerator, making it audible to the user, which may cause discomfort to the user.

[0005] A main object of the present disclosure is to provide a refrigerator control system and a refrigerator that can make the driving sound of a compressor, in particular the sound of the carrier frequency of inverter control, less audible to a user. [Means for solving the problem]

[0006] A refrigerator control system according to one aspect controls a drive circuit that drives a compressor provided in a refrigerator. The refrigerator control system includes a sound information acquisition unit that acquires sound information related to sounds around the refrigerator, a frequency determination unit that determines a carrier frequency of an inverter circuit included in the drive circuit based on the sound information acquired by the sound information acquisition unit, and an inverter control unit that controls the inverter circuit based on the carrier frequency determined by the frequency determination unit.

[0007] A refrigerator according to one aspect includes the refrigerator control system, a compressor, and a drive circuit controlled by the refrigerator control system and configured to drive the compressor. [Brief description of the drawings]

[0008] [Figure 1] FIG. 1 is a block diagram of a refrigerator including a refrigerator control system according to the first embodiment. [Diagram 2] FIG. 2 is an example of a graph of a frequency characteristic curve showing an allowable noise level. [Diagram 3] FIG. 3 is a flowchart showing an example of the operation of the refrigerator control system. [Figure 4] FIG. 4 is a flowchart showing an example of an operation of a process for determining a carrier frequency in the refrigerator control system according to the above embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] Hereinafter, an example of a preferred embodiment of the present invention will be described. However, the following embodiment is merely an example, and the present invention is not limited to the following embodiment.

[0010] (Embodiment 1) A refrigerator control system 1 of the present embodiment will be described with reference to Figs. 1 to 4.

[0011] The refrigerator control system 1 of this embodiment controls a drive circuit 3 that drives a compressor 2 provided in a refrigerator 100.

[0012] The refrigerator 100 has a refrigeration cycle mechanism. The refrigeration cycle mechanism has a compressor 2, a condenser, an expansion valve, an evaporator, and the like, and is configured to cool air by circulating a refrigerant while changing its phase.

[0013] The compressor 2 has a motor 21 and is configured to compress a gaseous refrigerant by the rotational driving of the motor 21. The compressor 2 is driven by a drive circuit 3.

[0014] The refrigerator 100 includes an AC / DC converter circuit 4 as a power supply circuit. The AC / DC converter circuit 4 is configured to convert AC power supplied from a commercial power supply into DC power. The AC / DC converter circuit 4 includes, for example, a rectifier circuit that rectifies an AC voltage, and a smoothing circuit that smoothes a pulsating voltage generated by the rectifier circuit. The AC / DC converter circuit 4 may also include a power factor correction (PFC) circuit, a step-down circuit, and the like.

[0015] The drive circuit 3 is configured to drive the compressor 2 using DC power supplied from the AC / DC converter circuit 4. Specifically, the drive circuit 3 is configured to drive the motor 21 of the compressor 2 to rotate. In this embodiment, the motor 21 is a three-phase motor, and the drive circuit 3 has an inverter circuit 31 that supplies three-phase AC power to the motor 21. The inverter circuit 31 is a three-phase full-bridge inverter circuit that has six full-bridge-connected switching elements (e.g., MOSFET: Metal Oxide Semiconductor Field Effect Transistor, IGBT: Insulated Gate Bipolar Transistor, etc.), and three output terminals are connected to the motor 21. The inverter circuit 31 converts a DC voltage into a three-phase AC voltage by driving the six switching elements on and off. The inverter circuit 31 applies the three-phase AC voltage to the motor 21 to rotate the motor 21.

[0016] The drive circuit 3 is controlled by the refrigerator control system 1. Specifically, the inverter circuit 31 of the drive circuit 3 is PWM-controlled by the refrigerator control system 1 (PWM: Pulse Width Modulation).

[0017] The refrigerator control system 1 includes an inverter control unit 11, a carrier signal generation unit 12, a frequency determination unit 13, a sound information acquisition unit 14, and a noise estimation unit 15.

[0018] The refrigerator control system 1 is configured with, for example, a microcomputer having a processor and a memory. That is, the refrigerator control system 1 is realized by a computer system having a processor and a memory. The processor executes an appropriate program to function as an inverter control unit 11, a carrier signal generating unit 12, a frequency determining unit 13, a sound information acquiring unit 14, and a noise estimating unit 15. The program may be pre-recorded in the memory, or may be provided via a telecommunication line such as the Internet, or recorded in a non-transitory recording medium such as a memory card. The processor of the computer system is configured with one or more electronic circuits including a semiconductor integrated circuit (IC) or a large scale integrated circuit (LSI). The electronic circuits may be integrated in one chip, or may be distributed across multiple chips. The chips may be integrated in one device, or may be distributed across multiple devices.

[0019] The inverter control unit 11 controls the inverter circuit 31. Specifically, the inverter control unit 11 PWM controls the inverter circuit 31 by outputting a PWM signal to the inverter circuit 31. The inverter circuit 31 outputs three-phase AC power to the motor 21 by turning on / off a plurality of switching elements in response to the PWM signal.

[0020] The inverter control unit 11 generates a PWM signal based on a carrier signal output from the carrier signal generation unit 12. Specifically, the inverter control unit 11 generates a PWM signal based on a comparison result between a modulation signal and a carrier signal. The modulation signal is generated by the modulation signal generation unit 16. The modulation signal is an AC signal corresponding to the phase and frequency of the AC voltage output from the inverter circuit 31. The carrier signal is, for example, a triangular wave, and is generated by the carrier signal generation unit 12. The pulse width of the PWM signal is determined according to a comparison result between the amplitude value of the modulation signal and the amplitude value of the carrier signal. In addition, the frequency of the carrier signal (hereinafter also referred to as the carrier frequency) determines the pulse width modulation period of the PWM signal. In this embodiment, the carrier frequency is variable. The carrier frequency is selected from a plurality of values, for example, 4 kHz, 8 kHz, and 12.5 kHz. The higher the carrier frequency, the closer the waveform of the AC voltage output from the inverter circuit 31 becomes to the modulation signal.

[0021] Carrier signal generating unit 12 generates a carrier signal having the carrier frequency determined by frequency determining unit 13 , and outputs the carrier signal to inverter control unit 11 .

[0022] The frequency determination unit 13 determines the carrier frequency based on the sound information acquired by the sound information acquisition unit 14. The frequency determination unit 13 determines the carrier frequency to be, for example, one of 4 kHz, 8 kHz, and 12.5 kHz based on the sound information. The process of determining the carrier frequency by the frequency determination unit 13 will be described later. Note that the value of the carrier frequency is not limited to the above values, and may be other values.

[0023] The sound information acquisition unit 14 acquires sound information that is information related to sounds around the refrigerator 100. In this embodiment, the sound information includes noise information based on an estimation result of the noise level around the refrigerator 100. The sound information acquisition unit 14 acquires the noise information as sound information from a noise estimation unit 15 that estimates the noise level around the refrigerator 100.

[0024] The noise estimation unit 15 estimates the noise level of the sound around the refrigerator 100. The noise estimation unit 15 estimates the noise level based on the output signal of the microphone 5 that acquires the sound around the refrigerator 100.

[0025] The microphone 5 is provided, for example, on a door panel of the refrigerator 100, and outputs an output signal corresponding to sounds around the refrigerator 100 to the noise estimation unit 15. The microphone 5 may be provided separately from the refrigerator 100. For example, the microphone 5 may be a microphone provided in a communication terminal such as a smartphone. In this case, the output signal of the microphone 5 is output from the smartphone to the noise estimation unit 15 of the refrigerator 100 by communication. The smartphone may be provided with the sound information acquisition unit 14, the noise estimation unit 15, and the like together with the microphone 5. In other words, a part of the refrigerator control system 1 may be provided in a distributed manner in a terminal such as a smartphone. In this case, information is exchanged between the refrigerator 100 and the smartphone by communication.

[0026] The noise estimation unit 15 estimates the noise level by performing signal processing on the output signal of the microphone 5. Specifically, the noise estimation unit 15 includes a bandpass filter and extracts a predetermined frequency band from the output signal of the microphone 5. The frequency band of the bandpass filter has, for example, a lower limit frequency of 353.6 Hz and an upper limit frequency of 5656.8 Hz. This frequency band is a band that is easily recognized as noise by humans. Note that the above frequency band values ​​are merely examples and are not limited to the above values, and other values ​​may be used.

[0027] Then, the noise estimation unit 15 integrates the signal components of the frequency band extracted by the bandpass filter. Based on the integration result, the noise estimation unit 15 calculates an RMS value (Root Mean Square (RMS)) as the noise level. The RMS value is the noise level when the sound pressure is uniform in the frequency band. In other words, the noise estimation unit 15 estimates the RMS value of a predetermined frequency band of the sound acquired by the microphone 5 as the noise level around the refrigerator 100. The noise estimation unit 15 outputs the estimated noise level (RMS value) to the sound information acquisition unit 14 as noise information.

[0028] Here, the noise estimation unit 15 of this embodiment estimates the noise level of the ambient environmental sound based on the output signal of the microphone 5 when the compressor 2 is stopped. The compressor 2 is intermittently controlled so that driving and stopping are repeated according to the temperature inside the refrigerator 100. In this embodiment, the microphone 5 acquires the sound around the refrigerator 100 when the compressor 2 is stopped and outputs an output signal to the noise estimation unit 15. The noise estimation unit 15 estimates the noise level based on the output signal of the microphone 5 when the compressor 2 is stopped. As a result, the noise level estimated by the noise estimation unit 15 does not include the driving sound of the compressor 2. Therefore, the estimation accuracy of the noise level of the ambient environmental sound generated around the refrigerator 100 is improved. Note that the noise estimation unit 15 may estimate the noise level at a timing before the compressor 2 starts operating when the refrigerator 100 is started up after the power is turned on.

[0029] Further, the sound information acquisition unit 14 acquires driving sound information on the driving sound of the compressor 2 according to the carrier frequency from the memory as sound information. In the memory, a plurality of values ​​that can be set as the carrier frequency and a driving sound level corresponding to each of the plurality of values ​​are stored as driving sound information. That is, in the memory, a representative value in the flat characteristic of the driving sound of the compressor 2 when each of the plurality of settable values ​​is set as the carrier frequency is stored as the driving sound level. In this embodiment, 4 kHz, 8 kHz, and 12.5 kHz can be set as the carrier frequency. When the carrier frequency is 4 kHz, the driving sound level is 27 dB. When the carrier frequency is 8 kHz, the driving sound level is 19 dB. When the carrier frequency is 12.5 kHz, the driving sound level is 30 dB.

[0030] In this way, the sound information acquisition unit 14 acquires noise information that is an estimation result of the noise level around the refrigerator 100, and driving sound information that is the driving sound level of the compressor 2 according to the carrier frequency. Then, the sound information acquisition unit 14 outputs sound information including the noise information and the driving sound information to the frequency determination unit 13.

[0031] The frequency determination unit 13 determines the carrier frequency of the inverter circuit 31 based on the noise information and the drive sound information.

[0032] Specifically, first, the frequency determination unit 13 calculates an acceptable noise level based on the noise information. The acceptable noise level is a frequency characteristic curve of a noise level that is estimated to blend in with sounds around the refrigerator 100 and is unlikely to cause discomfort to the user. Human hearing sensitivity has a characteristic that depends on frequency, and when the frequency is doubled, the hearing sensitivity also roughly doubles.

[0033] The frequency determination unit 13 calculates the allowable noise level based on the center frequency cf of the bandpass filter of the noise estimation unit 15 and the noise level estimated by the noise estimation unit 15. The center frequency cf is the center of the frequency band of the bandpass filter of the noise estimation unit 15. In this embodiment, the frequency band of the bandpass filter has a lower limit frequency of 353.6 Hz and an upper limit frequency of 5656.8 Hz. Therefore, the center frequency cf is 1414.3 Hz.

[0034] The frequency determination unit 13 sets the sound pressure of the center frequency cf at the allowable noise level to the noise level estimated by the noise estimation unit 15. Then, the frequency determination unit 13 calculates, as the allowable noise level, a frequency characteristic curve in which the sound pressure decreases by 3 dB for every octave increase in frequency from the center frequency cf, and increases by 3 dB for every octave decrease in frequency from the center frequency cf. The upper limit frequency of the allowable noise level may be about 10 kHz.

[0035] FIG. 2 shows an example of a frequency characteristic curve. In FIG. 2, the horizontal axis is frequency [Hz], the vertical axis is sound level [dB], the bar graph shows the driving sound level for each selectable carrier frequency (4 kHz, 8 kHz, 12.5 kHz), and the line graphs (a) to (c) are frequency characteristic curves showing the allowable noise level. In the example of FIG. 2, the driving sound level corresponding to a carrier frequency of 4 kHz is 27 dB, the driving sound level corresponding to a carrier frequency of 8 kHz is 19 bB, and the driving sound level corresponding to a carrier frequency of 12.5 kHz is 30 dB. Moreover, the line graph (a) is a frequency characteristic curve when the noise level of the center frequency cf is about 40 dB, the line graph (b) is a frequency characteristic curve when the noise level of the center frequency cf is about 30 dB, and the line graph (c) is a frequency characteristic curve when the noise level of the center frequency cf is about 20 dB.

[0036] The above-mentioned calculation method of the allowable noise level is an example, and the allowable noise level may be calculated by other calculation methods. For example, the allowable noise level may be calculated based on the equal roundness level curve shown in "ISO226.2003" as an auditory model.

[0037] The frequency determination unit 13 compares the allowable noise level with the driving noise level, and based on the comparison result, determines the carrier frequency to be set in the inverter circuit 31. Specifically, the frequency determination unit 13 compares the allowable noise level and the driving noise level corresponding to each of 4 kHz and 8 kHz, excluding 12.5 kHz, the highest of the three settable carrier frequencies (4 kHz, 8 kHz, 12.5 kHz).

[0038] For example, assume that the calculated frequency characteristic curve is the line graph (c) in Fig. 2. In this case, since the driving noise level exceeds the allowable noise level at both 4 kHz and 8 kHz, the frequency determination unit 13 determines the carrier frequency to be set in the inverter circuit 31 to be 12.5 kHz.

[0039] Moreover, it is assumed that the calculated frequency characteristic curve is the line graph (b) in Fig. 2. In this case, since the drive sound level corresponding to 4 kHz exceeds the allowable noise level and the drive sound level corresponding to 8 kHz is below the allowable noise level, the frequency determination unit 13 determines the carrier frequency to be set in the inverter circuit 31 to be 8 kHz.

[0040] Furthermore, if the drive noise level corresponding to 8 kHz exceeds the allowable noise level and the drive noise level corresponding to 4 kHz is below the allowable noise level, the frequency determination unit 13 determines the carrier frequency to be set in the inverter circuit 31 to be 4 kHz.

[0041] Also, assume that the calculated frequency characteristic curve is the line graph (a) in FIG. 2. In this case, since the driving sound level is below the allowable noise level at both 4 kHz and 8 kHz, the frequency determination unit 13 determines the carrier frequency to be set in the inverter circuit 31 to be 4 kHz or 8 kHz. For example, the frequency determination unit 13 determines the frequency having a larger difference between the driving sound level and the allowable noise level, between 4 kHz and 8 kHz, as the carrier frequency to be set in the inverter circuit 31. In the example of FIG. 2, the carrier frequency is determined to be 8 kHz in this case. Note that the frequency determination unit 13 may determine 4 kHz, which is the lower frequency with better energy efficiency, between 4 kHz and 8 kHz, as the carrier frequency to be set in the inverter circuit 31. Also, the frequency determination unit 13 may determine 8 kHz, which is the higher frequency that is harder for people to hear, between 4 kHz and 8 kHz, as the carrier frequency to be set in the inverter circuit 31.

[0042] The frequency determination unit 13 outputs the value of the determined carrier frequency to the carrier signal generation unit 12. The carrier signal generation unit 12 generates a carrier signal having the carrier frequency determined by the frequency determination unit 13 and outputs it to the inverter control unit 11. The inverter control unit 11 generates a PWM signal based on the carrier signal output from the carrier signal generation unit 12 and outputs it to the inverter circuit 31, thereby PWM-controlling the inverter circuit 31.

[0043] Next, an example of the operation of the refrigerator control system 1 of this embodiment will be described with reference to the flowcharts shown in FIG. 3 and FIG.

[0044] In this operation example, it is assumed that the compressor 2 is in a stopped state as an initial state.

[0045] First, in step S1, the refrigerator control system 1 determines whether or not a cooling start condition is satisfied. The cooling start condition is, for example, a condition that the temperature of the freezer compartment is equal to or higher than a first temperature. In other words, the cooling start condition is satisfied when the freezer compartment is not cooled. The cooling start condition and the cooling stop condition described later may depend not only on the temperature of the freezer compartment but also on the temperature of the refrigerator compartment, for example.

[0046] In step S1, if the cooling start condition is not satisfied, the refrigerator control system 1 continues the process of determining whether or not the cooling start condition is satisfied. In addition, in step S1, if the cooling start condition is satisfied, the rotation speed of the compressor 2 is determined to be a predetermined value in step S2.

[0047] Then, in step S3, a carrier frequency is determined to be set in the inverter circuit 31. The process of determining the carrier frequency in step S3 will be described in detail with reference to FIG.

[0048] In step S301, the noise estimation unit 15 estimates a noise level (RMS value) based on the output signal of the microphone 5. Then, the noise estimation unit 15 outputs the estimated noise level as noise information to the sound information acquisition unit 14. In addition, the sound information acquisition unit 14 acquires drive sound information related to the drive sound of the compressor 2 corresponding to the carrier frequency from the memory as sound information. The sound information acquisition unit 14 outputs sound information including the noise information and the drive sound information to the frequency determination unit 13.

[0049] In step S302, the frequency determination unit 13 calculates an allowable noise level based on the noise information. Here, it is assumed that the settable carrier frequencies are 4 kHz, 8 kHz, and 12.5 kHz, and the drive sound levels are 27 dB, 19 dB, and 30 dB, respectively.

[0050] In step S303, the frequency determination unit 13 compares the allowable noise level with the drive sound level. Specifically, the frequency determination unit 13 compares the allowable noise level and the drive sound level corresponding to each of 4 kHz and 8 kHz among three settable carrier frequencies (4 kHz, 8 kHz, 12.5 kHz).

[0051] If it is determined in step S303 that both the 4 kHz and 8 kHz driving sound levels exceed the allowable noise level, then in step S304, the frequency determination unit 13 determines the highest carrier frequency to be set in the inverter circuit 31, 12.5 kHz.

[0052] [Table 1] For example, as shown in Table 1, when the allowable noise levels corresponding to 4 kHz and 8 kHz are 15 dB and 12 dB, respectively, the corresponding difference value is a negative value. In this case, the frequency determination unit 13 determines the carrier frequency to be set in the inverter circuit 31 to be 12.5 kHz.

[0053] If the drive noise level is below the allowable noise level at least at 4 kHz and 8 kHz in step S303, the difference between the drive noise level and the allowable noise level is calculated in step S305. Then, in step S306, the frequency determination unit 13 determines the frequency corresponding to the largest difference value obtained by subtracting the drive noise level from the allowable noise level as the carrier frequency to be set in the inverter circuit 31.

[0054] [Table 2] For example, assume that the allowable noise levels corresponding to 4 kHz and 8 kHz are 35 dB and 32 dB, respectively, as shown in Table 2. In this case, the difference values ​​corresponding to 4 kHz and 8 kHz are 8 dB and 13 dB, respectively, so the frequency determination unit 13 determines the carrier frequency to be set in the inverter circuit 31 to be 8 kHz.

[0055] [Table 3] For example, assume that the allowable noise levels corresponding to 4 kHz and 8 kHz are 25 dB and 22 dB, respectively, as shown in Table 3. In this case, the difference values ​​corresponding to 4 kHz and 8 kHz are -2 dB and 3 dB, respectively, so the frequency determination unit 13 determines the carrier frequency to be set in the inverter circuit 31 to be 8 kHz.

[0056] In step S4 (see FIG. 3), the compressor 2 is started to operate. Specifically, the frequency determination unit 13 outputs the value of the determined carrier frequency to the carrier signal generation unit 12. The carrier signal generation unit 12 generates a carrier signal having the carrier frequency determined by the frequency determination unit 13 and outputs it to the inverter control unit 11. The inverter control unit 11 generates a PWM signal based on the carrier signal output from the carrier signal generation unit 12 and outputs it to the inverter circuit 31, thereby driving the compressor 2.

[0057] In step S5, the refrigerator control system 1 determines whether or not a cooling stop condition is satisfied. The cooling stop condition is, for example, a condition that the temperature of the freezer compartment is equal to or lower than a second temperature. In other words, when the storage compartment is sufficiently cold, the cooling stop condition is satisfied.

[0058] When the cooling stop condition is satisfied in step S5, the refrigerator control system 1 stops the compressor 2 in step S6. Then, returning to step S1, the refrigerator control system 1 determines whether the cooling start condition is satisfied.

[0059] On the other hand, if the cooling stop condition is not satisfied in step S5, the refrigerator control system 1 determines whether or not the rotation speed change condition of the compressor 2 is satisfied in step S7. The rotation speed change condition of the compressor 2 is, for example, a condition that the cooling speed of the freezer compartment is outside a predetermined speed range. For example, if the cooling speed of the freezer compartment is slower than the lower limit of the predetermined speed range, the rotation speed change condition of the compressor 2 is satisfied. In this case, the refrigerator control system 1 determines that the cooling capacity is insufficient, and increases the rotation speed of the compressor 2 by one step. Also, if the cooling speed of the freezer compartment is faster than the upper limit of the predetermined speed range, the rotation speed change condition of the compressor 2 is satisfied. In this case, the refrigerator control system 1 determines that the cooling capacity is excessive, and decreases the rotation speed of the compressor 2 by one step. If the rotation speed change condition of the compressor 2 is satisfied in step S7, the refrigerator control system 1 changes the rotation speed of the compressor 2 in step S8. Then, returning to step S5, the refrigerator control system 1 determines whether or not the cooling stop condition is satisfied. On the other hand, in step S7, if the rotation speed change condition of the compressor 2 is not satisfied, the process returns to step S5, and the refrigerator control system 1 determines whether the cooling stop condition is satisfied or not.

[0060] Note that the carrier frequency determination process may be performed after the process of changing the rotation speed of the compressor 2 in step S8. That is, the carrier frequency may be changed while the compressor 2 is operating. For example, the memory stores a driving sound level corresponding to the rotation speed of the compressor 2 in association with the carrier frequency. Then, in step S303 of the carrier frequency determination process, the driving sound level corresponding to the current rotation speed of the compressor 2 is compared with the allowable noise level, and the carrier frequency is determined based on the comparison result.

[0061] In this way, in the refrigerator control system 1 of this embodiment, a carrier frequency is selected based on sounds around the refrigerator 100 to drive the compressor 2. This allows the sound generated by the compressor 2 to blend in with the sounds around, making it less likely that the user will find the sound of the compressor 2 unpleasant.

[0062] (Modification) Next, a modified example of the refrigerator control system 1 of this embodiment will be described. The modified example described below can be applied by appropriately combining the configurations of the above-mentioned embodiment. In the following description, the same reference numerals will be used to denote the same configurations as those of the above-mentioned embodiment, and the description will be omitted as appropriate.

[0063] In refrigerator control system 1 of this modification, frequency determination unit 13 performs self-noise correction of the allowable noise level based on the currently set carrier frequency when changing the carrier frequency while compressor 2 is in operation. Based on the difference between the corrected allowable noise level and the operation level, frequency determination unit 13 determines the frequency corresponding to the largest difference value as the carrier frequency.

[0064] Specifically, the frequency determination unit 13 calculates a value obtained by subtracting the driving sound level LC of the currently set carrier frequency from the tolerable noise level LB corresponding to the currently set carrier frequency as the corrected tolerable noise level LZ. In other words, the following relational expression (1) holds between the tolerable noise level LB, the driving sound level LC, and the corrected tolerable noise level LZ.

[0065] 10 (LB / 10) -10 (LC / 10) =10 (LZ / 10) (1)

[0066] [Table 4] For example, as shown in Table 4, the drive sound levels corresponding to 4 kHz, 8 kHz, and 12.5 kHz are 24 dB, 20 dB, and 23 dB, respectively, and the allowable noise levels corresponding to 4 kHz, 8 kHz, and 12.5 kHz are 28 dB, 27 dB, and 26 dB, respectively. At this time, it is assumed that the carrier frequency being set is 12.5 kHz. In this case, the allowable noise level of 26 dB corresponding to the set carrier frequency of 12.5 kHz is superimposed with the drive sound level of the carrier frequency of 23 dB. Therefore, the frequency determination unit 13 performs self-noise correction to subtract the drive sound level of the carrier frequency from the allowable noise level of 26 dB corresponding to 12.5 kHz, and sets 23 dB as the corrected allowable noise level. Therefore, the difference values ​​between the corrected allowable noise level and the drive sound level corresponding to 4 kHz, 8 kHz, and 12.5 kHz are 4 dB, 7 dB, and 0 dB, respectively. Therefore, the frequency determination unit 13 determines 8 kHz, which corresponds to the largest difference value "7", as the carrier frequency.

[0067] In this way, when the carrier frequency is changed while the compressor 2 is operating, the allowable noise level is self-noise corrected based on the currently set carrier frequency. This makes it possible to correct the drive sound level of the carrier frequency even if the allowable noise level is calculated based on noise information acquired while the compressor 2 is operating, eliminating the need to stop the compressor 2 while acquiring the noise information.

[0068] (Embodiment 2) A description will be given of a refrigerator control system 1 according to the embodiment 2. In the following description, the same components as those in the above-described embodiment 1 will be denoted by the same reference numerals and the description will be omitted as appropriate.

[0069] In the refrigerator control system 1 of the present embodiment, the noise level estimation method used by the noise estimation unit 15 is different from the estimation method of the first embodiment.

[0070] The noise estimation unit 15 of this embodiment includes a plurality of bandpass filters corresponding to a plurality of settable carrier frequencies. In this embodiment, the noise estimation unit 15 includes a bandpass filter corresponding to 4 kHz and a bandpass filter corresponding to 8 kHz. The frequency band of the bandpass filter is about 1 / 3 octave centered on the value of the corresponding carrier frequency. For example, the frequency band of the bandpass filter corresponding to 4 kHz has a lower limit frequency of 3560 Hz and an upper limit frequency of 4490 Hz. Moreover, the frequency band of the bandpass filter corresponding to 8 kHz has a lower limit frequency of 7130 Hz and an upper limit frequency of 8980 Hz. Note that the frequency band of the bandpass filter is not limited to 1 / 3 octave, and may be set, for example, so that the respective frequency bands do not overlap according to the stages of the settable carrier frequency. Moreover, the noise estimation unit 15 may estimate the noise level from the frequency components near the carrier frequency using a frequency analysis tool such as FFT (Fast Fourier Transform) instead of the bandpass filter.

[0071] The noise estimation unit 15 integrates the signal components in the extracted frequency bands in each of the two band-pass filters, and calculates an RMS value as the noise level based on the integration results.

[0072] The frequency determination unit 13 sets the noise levels corresponding to 4 kHz and 8 kHz calculated by the noise estimation unit 15 as the allowable noise levels corresponding to 4 kHz and 8 kHz. Then, the frequency determination unit 13 compares the allowable noise level with the drive noise level, and determines the carrier frequency to be set in the inverter circuit 31 based on the comparison result.

[0073] [Table 5] For example, as shown in Table 5, the drive sound levels corresponding to 4 kHz, 8 kHz, and 12.5 kHz are 24 dB, 20 dB, and 23 dB, respectively, and the allowable noise levels corresponding to 4 kHz and 8 kHz are 38 dB and 23 dB, respectively. In this case, the difference values ​​corresponding to 4 kHz and 8 kHz are 14 dB and 3 dB, respectively, so the frequency determination unit 13 determines the carrier frequency to be set in the inverter circuit 31 to be 4 kHz, which has the largest difference value. Note that when the difference values ​​corresponding to 4 kHz and 8 kHz are both negative values, that is, when the drive sound level exceeds the allowable noise level, the frequency determination unit 13 determines the carrier frequency to be set in the inverter circuit 31 to be 12.5 kHz.

[0074] In this embodiment, the noise estimation unit 15 includes two bandpass filters corresponding to 4 kHz and 8 kHz, but may further include a bandpass filter corresponding to 12.5 kHz. In this case, the frequency determination unit 13 calculates difference values ​​corresponding to 4 kHz, 8 kHz, and 12.5 kHz, and determines the frequency with the largest difference value as the carrier frequency. Furthermore, if all difference values ​​are negative, the frequency determination unit 13 determines 12.5 kHz as the carrier frequency.

[0075] (Embodiment 3) A description will be given of a refrigerator control system 1 according to the embodiment 3. In the following description, the same components as those in the above-described embodiments 1 and 2 will be denoted by the same reference numerals and the description will be omitted as appropriate.

[0076] In the refrigerator control system 1 of this embodiment, in the process of determining the carrier frequency to be set in the inverter circuit 31 by the frequency determination unit 13, in addition to the processes in the first and second embodiments, a process of determining the carrier frequency is further performed so as to avoid frequencies that are easily heard by the user.

[0077] People's hearing may differ depending on age, sex, race, etc. Therefore, frequencies that are easy or difficult to hear may differ from person to person.

[0078] The sound information acquisition unit 14 of this embodiment further acquires exclusion information. The exclusion information is information about an exclusion sound set by a user. The sound information acquisition unit 14 acquires the exclusion information from a user interface such as an operation panel provided in the refrigerator 100, or a communication terminal such as a smartphone or a tablet terminal.

[0079] Specifically, the refrigerator control system 1 drives the compressor 2 at each of the settable carrier frequencies (4 kHz, 8 kHz, 12.5 kHz) and lets the user hear the drive sound of the compressor 2 corresponding to each carrier frequency. If the user finds any drive sound that is harsh and unpleasant to the ear, the user answers by using, for example, an operation panel, regarding the drive sound as an excluded sound. The sound information acquisition unit 14 acquires the answer from the user as the exclusion information. The sound information acquisition unit 14 may acquire the user's answer as the exclusion information from a communication terminal such as a smartphone that is communicatively connected to the refrigerator 100. The drive sound of the compressor 2 that is played to the user may be a pre-recorded sound that is played on a smartphone or the like.

[0080] The sound information acquisition unit 14 outputs sound information including the noise information, the drive sound information, and the exclusion information to the frequency determination unit 13.

[0081] The frequency determination unit 13 determines a carrier frequency to be set in the inverter circuit 31 based on the noise information, the drive sound information, and the exclusion information. Specifically, the frequency determination unit 13 excludes an exclusion frequency corresponding to the exclusion sound from the selection candidates of the carrier frequency based on the exclusion information. Then, the frequency determination unit 13 determines a carrier frequency from the remaining selection candidates.

[0082] For example, assume that the excluded frequency is 8 kHz. Also, as shown in Table 2 above, the drive sound levels of 4 kHz, 8 kHz, and 12.5 kHz are 27 dB, 19 dB, and 30 dB, respectively, and the allowable noise levels of 4 kHz and 8 kHz are 35 dB and 32 dB, respectively. In this case, the difference value corresponding to 4 kHz is 8 dB, which is smaller than the difference value of 13 dB corresponding to 8 kHz. However, since 8 kHz is the excluded frequency, the frequency determination unit 13 sets the carrier frequency to be set in the inverter circuit 31 to 4 kHz.

[0083] The exclusion information may include information that specifies sounds of multiple frequencies as the excluded sounds. If there is only one selectable frequency excluding the excluded frequency, the frequency determination unit determines this one frequency as the carrier frequency. In this case, the frequency determination unit can omit processes such as calculation of the allowable noise level and comparison between the allowable noise level and the driving sound level.

[0084] The exclusion information may also be a correction coefficient for the difference between the allowable noise level and the driving sound level. The correction coefficient is, for example, a value indicating a frequency that is tolerable or difficult to hear by the user. In this embodiment, the correction coefficient is indicated, for example, from 0 to 100%, and the higher the value, the more the frequency is tolerable by the user. The sound information acquisition unit 14 acquires, for example, the user's language, gender, age, questionnaire response, and the like, which are input to a communication terminal such as a smartphone that is communicatively connected to the refrigerator 100. The sound information acquisition unit 14 determines the correction coefficient for each frequency based on this information.

[0085] The frequency determination unit 13 calculates a score by multiplying the difference between the allowable noise level and the drive sound level by the correction coefficient, and determines the frequency corresponding to the largest score as the carrier frequency.

[0086] [Table 6] For example, as shown in Table 6, the driving sound levels corresponding to 4 kHz, 8 kHz, and 12.5 kHz are 24 dB, 20 dB, and 23 dB, respectively. In addition, the allowable noise levels corresponding to 4 kHz and 8 kHz are 38 dB and 35 dB. In addition, the correction coefficients corresponding to 4 kHz and 8 kHz are 80% and 20%, respectively. In this case, the difference value corresponding to 4 kHz is 14 dB, which is smaller than the difference value corresponding to 8 kHz, which is 15 dB. However, the scores corresponding to 4 kHz and 8 kHz are "11.2" and "3", respectively. Therefore, the frequency determination unit 13 sets the carrier frequency to be set in the inverter circuit 31 to 4 kHz.

[0087] In this embodiment, similarly to the second embodiment, the noise estimation unit 15 may include three bandpass filters corresponding to 4 kHz, 8 kHz, and 12.5 kHz, and calculate the allowable noise levels corresponding to 4 kHz, 8 kHz, and 12.5 kHz, respectively. In this case, the frequency determination unit 13 calculates the score for each of 4 kHz, 8 kHz, and 12.5 kHz by multiplying the difference value and the correction coefficient. Then, the frequency determination unit 13 determines the frequency corresponding to the largest score as the carrier frequency.

[0088] [Table 7] For example, as shown in Table 7, the allowable noise levels corresponding to 4 kHz, 8 kHz, and 12.5 kHz are 38 dB, 23 dB, and 20 dB, respectively, the difference values ​​are 14 dB, 3 dB, and -3 dB, respectively, and the correction coefficients are 50%, 20%, and 30%, respectively. In this case, the scores corresponding to 4 kHz, 8 kHz, and 12.5 kHz are "7", "0.6", and "-0.9", respectively. Therefore, the frequency determination unit 13 determines 4 kHz, which corresponds to the largest score "7", as the carrier frequency. [Explanation of symbols]

[0089] 100 Refrigerator 1 Refrigerator control system 11 Inverter control unit 13 Frequency determination section 14 Sound information acquisition unit 15 Noise Estimation Section 2. Compressor 3. Drive circuit 31 Inverter circuit 5 Microphone

Claims

1. A refrigerator control system that controls a drive circuit that drives a compressor provided in a refrigerator, a sound information acquisition unit that stores drive sound information related to the drive sound of the compressor corresponding to each of a plurality of carrier frequencies that can be set by an inverter circuit of the drive circuit; a noise estimation unit that estimates a noise level around the refrigerator based on an output signal of a microphone that acquires sounds around the refrigerator; a frequency determination unit that calculates an allowable noise level based on the ambient noise level of the refrigerator estimated by the noise estimation unit, and determines a carrier frequency of an inverter circuit of the drive circuit based on a result of comparing the drive sound information acquired by the sound information acquisition unit with the allowable noise level for each of the plurality of carrier frequencies; An inverter control unit that controls the inverter circuit based on the carrier frequency determined by the frequency determination unit. Refrigerator control system.

2. the frequency determination unit calculates the allowable noise level by applying the noise level in a predetermined frequency band estimated by the noise estimation unit to a frequency characteristic curve based on a predetermined auditory hearing model.

2. The refrigerator control system of claim 1.

3. The noise estimation unit estimates the noise level based on an output signal of the microphone when the compressor is stopped.

2. The refrigerator control system of claim 1.

4. The frequency determination unit determines the carrier frequency while avoiding an exclusion frequency corresponding to an exclusion sound set by a user. The refrigerator control system according to any one of claims 1 to 3.

5. A refrigerator control system according to any one of claims 1 to 4; A compressor; A drive circuit controlled by the refrigerator control system and driving the compressor. refrigerator.

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