JP2021168544A - Inverter control device, inverter control method, and inverter control program - Google Patents

Abstract

To provide an inverter control device, an inverter control method, and an inverter control program that can improve the hearing sensation.SOLUTION: An inverter control device includes a setting unit 25 that sets a carrier cycle on the basis of the rotation speed of a motor driven by an inverter, a carrier wave generation unit 23 that combines a plurality of waveform elements having different periods to form a waveform corresponding to the carrier period and generates a carrier wave composed of repeated waveforms, and a PWM signal generation unit 22 that generates a PWM signal for the inverter by a comparison method using the carrier wave and a predetermined modulated wave.SELECTED DRAWING: Figure 3

Description

The present disclosure relates to an inverter control device, an inverter control method, and an inverter control program.

The motor of the compressor mounted on the air conditioner is controlled by an inverter. The inverter is controlled by a PWM signal generated by using a carrier wave (PWM control).

Patent Document 1 discloses that the carrier frequency is switched according to the voltage of a commercial power source or the like.

Japanese Patent No. 4352883

However, when a PWM signal is generated using a carrier wave, a high frequency ripple component due to the frequency of the carrier wave is included in the current output from the inverter. Therefore, an electromagnetic or vibrational sound (carrier sound) may be generated in the motor into which the current flows. In particular, the carrier frequency is often about several kHz, and it is known that it is easy for humans to perceive.

In Patent Document 1, although the carrier frequency is switched according to the voltage of the commercial power supply or the like, a constant carrier frequency is used under certain operating conditions (for example, when the voltage of the commercial power supply is constant), so that the carrier sound is still sufficient. It cannot be suppressed and may cause discomfort to the user.

Further, in a motor driven by an inverter, there is a frequency at which resonance operation may occur depending on the motor rotation speed, and when the carrier frequency has an integral multiple relationship with the frequency, a roaring noise, which is noise due to resonance, is generated. May be done.

The present disclosure has been made in view of such circumstances, and an object of the present invention is to provide an inverter control device, an inverter control method, and an inverter control program capable of improving the hearing sensation.

The inverter control device according to the first aspect of the present disclosure corresponds to the carrier cycle by combining a setting unit that sets a carrier cycle based on the rotation speed of a motor driven by the inverter and a plurality of waveform elements having different cycles. A PWM signal generation unit that forms a waveform and generates a carrier wave formed by repeating the waveform, and a PWM signal generation unit that generates a PWM signal for the inverter by a comparison method using the carrier wave and a predetermined modulated wave. It has a part and.

In the inverter control method according to the second aspect of the present disclosure, a step of setting a carrier cycle based on the rotation speed of a motor driven by an inverter and a waveform corresponding to the carrier cycle by combining a plurality of waveform elements having different cycles are used. It has a step of generating a carrier wave composed of repeating the waveform, and a step of generating a PWM signal for the inverter by a comparison method using the carrier wave and a predetermined modulated wave.

The inverter control program according to the third aspect of the present disclosure combines a process of setting a carrier period based on the rotation speed of a motor driven by an inverter and a plurality of waveform elements having different periods to provide a waveform corresponding to the carrier period. The computer executes a process of generating a carrier wave composed of repeating the waveform and a process of generating a PWM signal for the inverter by a comparison method using the carrier wave and a predetermined modulated wave. Let me.

According to the present disclosure, it is possible to improve the hearing sensation.

It is a figure which shows the schematic structure of the motor drive device in the air conditioner which concerns on 1st Embodiment of this disclosure. It is a figure which shows an example of the hardware composition of the motor drive device in the air conditioner which concerns on 1st Embodiment of this disclosure. It is a functional block diagram which showed the function which the inverter control device which concerns on 1st Embodiment of this disclosure has. It is a figure which showed the modification of the carrier cycle which concerns on 1st Embodiment of this disclosure. It is a figure which shows the schematic structure of the motor drive device in the air conditioner which concerns on 1st Embodiment of this disclosure. It is a figure which shows the structural example of the carrier wave which concerns on 1st Embodiment of this disclosure. It is a figure which shows the structural example of the carrier wave which concerns on 1st Embodiment of this disclosure. It is a figure which shows the state example of the PWM signal which concerns on 1st Embodiment of this disclosure. It is a figure which shows the structural example of the carrier wave which concerns on 1st Embodiment of this disclosure. It is a figure which shows the structural example of the carrier wave which concerns on 1st Embodiment of this disclosure. It is a figure which showed the flowchart of the PWM signal generation processing by the inverter control device which concerns on 1st Embodiment of this disclosure. It is a figure which showed the effect of the PWM signal generation processing which concerns on 1st Embodiment of this disclosure. It is a figure which shows the setting example of the occurrence probability which concerns on 2nd Embodiment of this disclosure. It is a figure which shows the structural example of the carrier wave which concerns on 2nd Embodiment of this disclosure. It is a figure which shows the structural example of the carrier wave which concerns on 3rd Embodiment of this disclosure. It is a figure which shows an example of the resonance characteristic which concerns on 4th Embodiment of this disclosure.

[First Embodiment]
Hereinafter, the inverter control device, the inverter control method, and the first embodiment of the inverter control program according to the present disclosure will be described with reference to the drawings.

(Structure of motor drive device)
FIG. 1 is a diagram showing a schematic configuration of a motor drive device 1 in the air conditioner according to the first embodiment of the present disclosure. Note that FIG. 1 describes a case where the motor of the compressor is driven by the inverter 8, but the inverter control device 20 in the present embodiment is limited to the above as long as it is a device that drives the load by PWM controlling the inverter 8. It is possible to apply without.

FIG. 1 shows a schematic configuration of a motor drive device 1 that drives a compressor motor (motor that drives a compressor) 9.

The motor drive device 1 drives the motor of the compressor based on the electric power supplied from the AC power supply 4. Specifically, in the motor drive device 1, the converter and the inverter 8 are connected to the AC power supply 4. The converter is a device that rectifies the AC voltage supplied from the AC power supply 4 and converts it into a DC voltage. Therefore, the converter has, for example, a rectifier circuit 5, an inductance unit 6, and a capacitor unit 7.

The rectifier circuit 5 is connected in parallel to the AC power supply 4 and rectifies the AC voltage supplied from the AC power supply 4. For example, the rectifier circuit 5 is composed of a bridge rectifier circuit or the like using a diode, and full-wave rectifies the AC voltage supplied from the AC power supply 4. The rectification method may be another rectification method such as half-wave rectification.

The inductance unit 6 is connected in series to the positive electrode DC electric circuit on the output side of the rectifier circuit 5. The inductance unit 6 may be connected in series to the negative electrode DC electric circuit on the output side of the rectifier circuit 5. The capacitor unit 7 is connected in parallel to the rectifier circuit 5 via the inductance unit 6. Although the voltage output from the rectifier circuit 5 is rectified, it is pulsating (including high-frequency components). Therefore, by providing the inductance portion 6 and the capacitor portion 7 on the output side of the rectifier circuit 5, pulsating current occurs. Inhibits and smoothes components.

In the converter, the rectifier circuit 5, the inductance section 6, and the capacitor section 7 generate a DC voltage and output it to the inverter 8.

The inverter 8 generates a three-phase AC voltage based on the DC voltage supplied from the converter, and drives the compressor motor (load) 9. The inverter 8 is, for example, a bridge circuit composed of six switching elements, and each switching element is switched and controlled based on a PWM signal input from an inverter control device 20 described later. The inverter 8 may be a single-phase type or a multi-phase type depending on the load to be driven.

The inverter control device 20 generates a PWM signal and controls the inverter 8.

(Hardware configuration diagram of inverter controller)
FIG. 2 is a diagram showing an example of the hardware configuration of the inverter control device 20 according to the present embodiment.
As shown in FIG. 2, the inverter control device 20 is a computer system (computer system), for example, a CPU 11, a ROM (Read Only Memory) 12 for storing a program or the like executed by the CPU 11, and each program execution. It includes a RAM (Random Access Memory) 13 that functions as a work area at the time, a hard disk drive (HDD) 14 as a large-capacity storage device, and a communication unit 15 for connecting to a network or the like. Each of these parts is connected via a bus 18.

Further, the inverter control device 20 may include an input unit including a keyboard, a mouse, and the like, a display unit including a liquid crystal display device for displaying data, and the like.

The storage medium for storing the program or the like executed by the CPU 11 is not limited to the ROM 12. For example, it may be another auxiliary storage device such as a magnetic disk, a magneto-optical disk, or a semiconductor memory.

A series of processing processes for realizing various functions described later is recorded in the hard disk drive 14 or the like in the form of a program, and the CPU 11 reads this program into the RAM 13 or the like to execute information processing / arithmetic processing. As a result, various functions described later are realized. The program is installed in ROM 12 or other storage medium in advance, is provided in a state of being stored in a computer-readable storage medium, or is distributed via a wired or wireless communication means. Etc. may be applied. Computer-readable storage media include magnetic disks, magneto-optical disks, CD-ROMs, DVD-ROMs, semiconductor memories, and the like.

(Functional configuration diagram of the inverter control device)
FIG. 3 is a functional block diagram showing the functions included in the inverter control device 20. As shown in FIG. 3, the inverter control device 20 includes an acquisition unit 21, a setting unit 25, a carrier wave generation unit 23, and a PWM signal generation unit 22.

The acquisition unit 21 acquires the current at a predetermined position in the inverter 8. Specifically, the acquisition unit 21 acquires the current information detected by the current sensor 24. FIG. 1 illustrates a case where the one-shunt method is used as the current detection method. That is, in FIG. 1, the current flowing through the inverter 8 (combined current of each phase current) is detected by the current sensor 24 and output to the acquisition unit 21. That is, the acquisition unit 21 acquires the combined current of each phase current. In the present embodiment, since the inverter 8 is a multi-phase type, the acquisition unit 21 acquires the combined current of each phase current, but when the inverter 8 is a single-phase type, the acquisition unit 21 is acquired. Detects the current of the phase itself by the current sensor 24.

The acquisition unit 21 calculates the current (Iu, Iv, Iw) of each phase from the detection result of the combined current of each phase current. Specifically, the acquisition unit 21 calculates each phase current (Iu, Iv, Iw) based on the acquired combined current and the PWM signal generated by the PWM signal generation unit 22, which will be described later, and the PWM signal. Output to the generation unit 22. If each phase current can be calculated from the combined current, it does not have to be based on the PWM signal.

When the three-shunt method is used as the current detection method, the motor drive device 1 has the configuration as shown in FIG. That is, the current corresponding to each phase at the output position of the inverter 8 is detected by the current sensor 24 and output to the acquisition unit 21. That is, the acquisition unit 21 can acquire each phase current. Therefore, the acquisition unit 21 outputs each acquired phase current to the PWM signal generation unit 22.

The current acquisition method is not limited to the one-shunt method or the three-shunt method as described above as long as each phase current can be acquired.

The setting unit 25 sets the carrier cycle based on the rotation speed of the compressor motor 9 driven by the inverter 8. Specifically, the setting unit 25 sets the carrier so that the ratio between the period of the current fundamental wave component flowing through the compressor motor 9 according to the rotation speed and the carrier period does not fall within a predetermined numerical range including an integer. Set the cycle.

The carrier wave (frequency diffusion carrier wave) is a periodic waveform in which a constant waveform is repeated at a constant cycle as described later. For example, as will be described later, when each waveform element of 3.15 kHz (fa), 4 kHz (fb), 5 kHz (fc), 6.3 kHz (fd), and 8 kHz (fe) is configured three times in succession (FIG. In 7), one period of the carrier wave is (0.317 msec × 3) + (0.25 msec × 3) + (0.2 msec × 3) + (0.159 msec × 3) + (0.125 msec × 3). ) = 3.153 msec.

On the other hand, when the number of revolutions of the compressor motor 9 driven by the inverter 8 is N [rpm] and the number of poles is P [−], the frequency fe of the fundamental wave component of the current flowing through the compressor motor 9 is set. fe = (N × P) / 120. Since the period Te is the reciprocal of the frequency fe, Te = 120 / (N × P). For example, when the rotation speed is 1600 [rpm] and the number of poles is 6, the period Te = 120 / (1600 × 6) = 12.5 msec.

That is, when the compressor motor 9 is in an operating state where the period Te = 12.5 msec and the carrier period is 3.153 msec, the period of the current fundamental wave component flowing through the compressor motor 9 and the carrier. The ratio with the period is almost an integral multiple (12.5 msec / 3.153 msec ≈ 4). As described above, when the ratio between the period of the current fundamental wave component flowing through the compressor motor 9 and the carrier period is approximately an integral multiple, a roaring sound due to the resonance operation may be generated.

The ratio between the period of the current fundamental wave component flowing through the compressor motor 9 and the carrier period is larger than the smaller value of the period and carrier period of the current fundamental wave component flowing through the compressor motor 9. The ratio of the one. That is, the period of the current fundamental wave component flowing through the compressor motor 9: the carrier period may be 1: n (n is an integer) or n: 1 (n is an integer). Further, since the frequency has a reciprocal relationship of the period, the same applies even when it is considered as a frequency.

When the ratio of the period of the current fundamental wave component flowing through the compressor motor 9 to the carrier period is close to an integer, a roaring sound may be generated due to the resonance operation. Therefore, a roaring sound is generated in the setting unit 25. To prevent this, the carrier period, which is the period of the carrier wave generated by the carrier wave generation unit 23 described later, is set.

In order to set the carrier cycle, the setting unit 25 acquires the rotation speed of the compressor motor 9. The number of poles is preset according to the specifications of the compressor motor 9 that is configured. Then, the setting unit 25 calculates the period of the fundamental wave component of the current flowing through the compressor motor 9 using a predetermined calculation formula (Te = 120 / (N × P)).

Then, the setting unit 25 sets the carrier period so that the ratio between the period of the current fundamental wave component flowing through the compressor motor 9 according to the rotation speed and the carrier period does not fall within a predetermined numerical range including an integer. do. That is, the carrier period is set so that the ratio between the period of the current fundamental wave component and the carrier period does not become an integral multiple (a multiple of a value close to an integer). The predetermined numerical range includes an integer, and is a numerical range set by adding a predetermined margin to the integer. That is, the numerical range is provided for each integer and is a range indicating the neighborhood of each integer. For example, the predetermined margin is set to 0.3. In this case, the numerical range is set to a range obtained by adding or subtracting 0.3 to an integer. Specifically, assuming that the integers are 1, 2, 3, 4, 5, ..., The numerical range is a range of 0.7 or more and 1.3 or less, a range of 1.7 or more and 2.3 or less, and 2. It is set as a range of 7 or more and 3.3 or less, a range of 3.7 or more and 4.3 or less, a range of 4.7 or more and 5.3 or less, and the like. In other words, the carrier cycle is set so that the decimal point portion of the ratio is about 0.5.

The margin in the numerical range can be appropriately set as long as it is smaller than 0.5, and may be 0.1 or the like depending on the resonance characteristics. Further, the numerical range for an integer is not limited to the method of adding or subtracting a predetermined margin, and may be set including an integer.

The setting unit sets a carrier period that does not fall within the numerical range with respect to the period of the fundamental wave component of the calculated current. For example, a carrier cycle corresponding to a plurality of waveform patterns in which each waveform element is combined is prepared, and a carrier cycle that does not fall within the numerical range with respect to the cycle of the fundamental wave component of the current is set from among the plurality of carrier cycles. .. Further, the setting unit may set a carrier cycle range (carrier cycle range) that is not a numerical range with respect to the cycle of the fundamental wave component of the current.

The method for setting the carrier period is not limited to the above as long as the carrier period that does not fall within the numerical range with respect to the period of the fundamental wave component of the current is set.

FIG. 4 is a diagram showing an example of changing the carrier cycle. In FIG. 4, the vertical axis represents the frequency and the ratio, and the horizontal axis represents the rotation speed of the compressor motor 9. In FIG. 4, the carrier cycle is shown as the carrier frequency (reciprocal of the carrier cycle) fh. The period of the current fundamental wave component is shown as the frequency fi. Further, in FIG. 4, integers are illustrated as N1 and N2 with respect to the ratio. As shown in FIG. 4, since the number of poles is constant depending on the specifications of the compressor motor 9, the frequency fi of the current fundamental wave component changes depending on the rotation speed. When the frequency fi of the current fundamental wave component changes in this way, the ratio (in this case, the ratio of the carrier frequency to the frequency of the current fundamental wave component) R decreases when the carrier frequency fh is constant, and is an integer (FIG. 4). Approaching N1). Then, when the ratio R reaches a predetermined numerical range, a roaring sound may be generated, so that the carrier frequency (carrier period) fh is changed. Since the carrier cycle is set appropriately in this way, the ratio R is outside the predetermined numerical range (that is, the region between the numerical range corresponding to a certain integer and the numerical range corresponding to an integer that is one larger value). Can be. Therefore, the generation of growl noise can be suppressed.

The carrier wave generation unit 23 combines a plurality of waveform elements having different periods to form a waveform corresponding to the carrier period, and generates a carrier wave (frequency diffusion carrier wave) composed by repeating the waveform. That is, the carrier wave generation unit 23 forms a waveform so that the length (period) becomes the set carrier period by combining each waveform element having a different period, and the waveform is used as a waveform for one cycle. By repeating the process, a carrier wave, which is a periodic waveform, is generated. That is, the carrier wave is a waveform in which the combination waveform of each waveform element is repeated in the carrier cycle. The length of the waveform obtained by combining each waveform element is preferably the same as the carrier period, but the ratio can be set to a value close to the carrier period unless the ratio is within a predetermined numerical range including an integer. .. The carrier wave is a signal to be compared with a modulated wave described later in generating a PWM signal. In the present embodiment, the case where a triangular wave is used as the carrier wave will be described, but a carrier wave having another waveform such as a sawtooth wave may be used.

The plurality of waveform elements having different cycles are waveforms for one cycle in a plurality of types of cycle waveforms selected in advance. That is, the waveform elements are provided corresponding to a plurality of periods (frequency). For example, when the periodic waveform is a triangular wave, the triangular waveform is repeated at a constant period, and the triangular waveform (waveform for one cycle) is a waveform element corresponding to the period (frequency). Become. In the present embodiment, the carrier wave generation unit 23 has five types of frequencies (carriers) corresponding to 3.15 kHz (fa), 4 kHz (fb), 5 kHz (fc), 6.3 kHz (fd), and 8 kHz (fe). It is assumed that the waveform element of (frequency) is set. Note that carrier sound (electromagnetic noise generated due to the frequency of the carrier wave) is generated due to the frequency of the carrier wave. Therefore, the period of the waveform element constituting the carrier wave may be selected based on the resonance characteristic of the structure (for example, the compressor or the compressor motor 9) provided on the output side of the inverter 8.

The carrier wave generation unit 23 generates a carrier wave by combining each waveform element corresponding to a plurality of types of periods. That is, since the carrier wave is no longer a waveform in which a constant waveform shape is repeated at a constant cycle, it is possible to suppress an increase in the carrier sound at a specific frequency.

In order not to generate a large carrier sound at a specific frequency, it is preferable that the carrier wave is a dispersion and combination of waveform elements corresponding to as many periods as possible. That is, it is preferable that the adjacent waveform elements have different periods. However, even when a plurality of waveform elements having the same period are continuously configured, the frequency dispersion of the carrier sound can be performed by setting the number of continuations to be small.

The number of consecutive waveform elements with the same period is affected, for example, by obtaining the current value. In the present embodiment, current acquisition will be described as an example, but the current acquisition is not limited as long as it is a factor that affects the number of consecutive waveform elements having the same period. Specifically, the current acquisition is a one-shunt method or a three-shunt method. The configuration shown in FIG. 1 is a one-shunt system. The method shown in FIG. 5 is a three-shunt method. That is, the three-shunt method is a method in which each phase current can be directly acquired, and the one-shunt method is a method in which the combined current of each phase current is acquired.

6 and 7 are configuration examples of carrier waves when the current detection method corresponds to the one-shunt method (FIG. 1). In the one-shunt method, since the combined current of each phase current is detected, it may take longer to detect as compared with the three-shunt method. Specifically, in the one-shunt method, the current reading timing is first determined (first cycle), the current reading is executed (second cycle), and then control (PWM control) is performed based on, for example, the read current. Do (third cycle). FIG. 8 is a diagram illustrating a change state of the PWM signal of each phase. In FIG. 8, the vertical axis represents the value (voltage value) of each signal, and the horizontal axis represents time. As shown in FIG. 8, the PWM signal of each phase changes in one cycle of the carrier wave, and the current that can be acquired by the one-shunt method differs depending on the signal state. FIG. 8 illustrates a case (mode) in which a u-phase current (Iu) and a w-phase current (-Iw) appear in one cycle, and the mode differs depending on the relationship between the carrier wave and the modulated wave. , Changes in each cycle (Fig. 8 is an example of the mode). That is, Iu can be acquired from the current sensor 24 at the timings of A and D, and −Iw can be acquired from the current sensor 24 at the timings of B and C. Therefore, in the one-shunt method, the mode in the next cycle (which phase current can be detected at which timing) is first determined (first cycle), and the current is detected at the determined timing in the next cycle (first cycle). Second cycle). Then, in the next cycle, control is performed based on the acquired current (third cycle). Then, the processing of the first cycle is performed again in the next cycle. As described above, in the one-shunt method, the first cycle, the second cycle, and the third cycle (for three cycles) are required when performing from the acquisition of the current to the control. Therefore, when a carrier wave is generated in the one-shunt method, the first period, the second period, and the third period (for three cycles) are formed by constructing waveform elements having the same period three times in succession. It is possible to secure and perform processing. Further, since the same period is used for three cycles, the complexity of control can be suppressed.

FIG. 6 shows an example in which a carrier wave is configured by using waveform elements of 3.15 kHz (fa) and 4 kHz (fb). Each of the 3.15 kHz (fa) and 4 kHz (fb) waveform elements is composed of three consecutive waveform elements. In FIG. 6, the carrier period in the carrier wave is T1. That is, a waveform is formed by combining 3.15 kHz (fa) and 4 kHz (fb) waveform elements corresponding to the carrier period T1, and a carrier wave is formed by repeating the waveform.

FIG. 7 shows an example in which a carrier wave is configured by using waveform elements of 3.15 kHz (fa), 4 kHz (fb), 5 kHz (fc), 6.3 kHz (fd), and 8 kHz (fe). Three consecutive waveform elements of 3.15 kHz (fa), 4 kHz (fb), 5 kHz (fc), 6.3 kHz (fd), and 8 kHz (fe) are configured. In FIG. 7, the carrier period in the carrier wave is T2. That is, a waveform is formed by combining waveform elements of 3.15 kHz (fa), 4 kHz (fb), 5 kHz (fc), 6.3 kHz (fd), and 8 kHz (fe) corresponding to the carrier period T2. A carrier wave is formed by repeating the waveform.

In addition, when the one-shunt method is applied, the control that affects each phase current based on the current is not performed only by acquiring the current, or the control can be executed within the second cycle. In the case of, the third cycle as described above can be eliminated. That is, for the carrier wave, in order to secure the first period and the second period, the waveform elements having the same period may be configured twice in succession. Further, even when the one-shunt method is applied, if it is not necessary to continuously configure the waveform elements having the same period, the waveform elements may be combined as shown in FIGS. 9 and 10. good.

9 and 10 are configuration examples of carrier waves when the current detection method corresponds to the three-shunt method. In the three-shunt method, each phase current can be obtained directly. Therefore, it is possible to configure the waveform elements having different periods to be adjacent to each other without making the waveform elements having the same period continuous. FIG. 9 shows an example in which a carrier wave is configured by using waveform elements of 3.15 kHz (fa) and 4 kHz (fb). Since the adjacent waveform elements can have different periods, the 3.15 kHz (fa) and 4 kHz (fb) waveform elements are adjacent to each other. In FIG. 9, the carrier period in the carrier wave is T3. That is, a waveform is formed by combining 3.15 kHz (fa) and 4 kHz (fb) waveform elements corresponding to the carrier period T3, and a carrier wave is formed by repeating the waveform.

FIG. 10 shows an example in which a carrier wave is configured by using waveform elements of 3.15 kHz (fa), 4 kHz (fb), 5 kHz (fc), 6.3 kHz (fd), and 8 kHz (fe). Since adjacent waveform elements can have different periods, 3.15 kHz (fa), 4 kHz (fb), 5 kHz (fc), 6.3 kHz (fd), and 8 kHz (fe) waveform elements are adjacent to each other. It has become. In FIG. 10, the carrier period in the carrier wave is T4. That is, a waveform is formed by combining waveform elements of 3.15 kHz (fa), 4 kHz (fb), 5 kHz (fc), 6.3 kHz (fd), and 8 kHz (fe) corresponding to the carrier period T4. A carrier wave is formed by repeating the waveform. Even in the case of the three-shunt method, waveform elements having the same period may be continuous.

The PWM signal generation unit 22 generates a PWM signal for the inverter 8 by a comparison method using a carrier wave and a predetermined modulated wave. The carrier wave is a carrier wave generated by the carrier wave generation unit 23. The modulated wave is a signal to be compared with a carrier wave, and in the present embodiment, it is a three-phase voltage modulated wave (reference signal) because it generates a PWM signal corresponding to three phases. That is, a PWM signal corresponding to each phase is generated by comparing one carrier wave and three modulated waves (modulated waves corresponding to each of the three phases). By driving the inverter 8 with the generated PWM signal, a three-phase voltage signal is output and the compressor motor 9 is driven.

Specifically, the PWM signal generation unit 22 includes a command calculation unit 31, a modulation wave generation unit 32, and a comparison unit 33.

The command calculation unit 31 calculates a voltage command based on each phase current output from the acquisition unit 21. Specifically, the command calculation unit 31 generates a three-phase voltage command, which is a voltage command corresponding to each phase, from each phase current input from the acquisition unit 21, and outputs the three-phase voltage command to the modulated wave generation unit 32.

The modulated wave generation unit 32 generates a modulated wave based on the three-phase voltage command. Specifically, the modulated wave generation unit 32 generates a three-phase modulated wave, which is a modulated wave corresponding to each phase, from the three-phase voltage command input from the command calculation unit 31, and outputs the three-phase modulated wave to the comparison unit 33.

The comparison unit 33 compares the carrier wave generated by the carrier wave generation unit 23 with the modulated wave corresponding to each phase generated by the modulated wave generation unit 32, and generates a three-phase PWM signal. Specifically, the comparison unit 33 generates a PWM signal by a PWM signal generation method (triangular wave comparison method) using a comparison method. For example, the PWM signal corresponding to the u phase is generated with the PWM signal corresponding to the u phase in the ON state (High) while the carrier wave has a value equal to or higher than the modulated wave corresponding to the u phase. While the carrier wave has a value less than the modulated wave corresponding to the u phase, the PWM signal corresponding to the u phase is generated as an OFF state (Low). The PWM signals corresponding to the other phases are similarly generated.

The PWM signal is generated as described above and is input to the switching element of each phase in the inverter 8. By controlling each switching element of the inverter 8 by a PWM signal, a three-phase voltage is output to drive the compressor motor 9.

(Processing flow by the inverter control device)
Next, an example of PWM signal generation processing by the above-mentioned inverter control device 20 will be described with reference to FIG. FIG. 11 is a flowchart showing an example of the procedure of the PWM signal generation processing according to the present embodiment. The flow shown in FIG. 11 is repeatedly executed at a predetermined control cycle, for example, when the air conditioner is operating.

First, the current at a predetermined position in the inverter 8 is acquired (S101). Regarding current acquisition, the acquisition position differs depending on the acquisition method such as the 1-shunt method or the 3-shunt method.

Next, each phase current is calculated (S102). Regarding S102, it can be omitted in the case of the 3-shunt system.

Next, a voltage command is calculated based on each phase current, and a modulated wave is generated based on the voltage command (S103).

Next, the rotation speed of the compressor motor 9 is acquired and the carrier cycle is set (S104).

Next, the carrier wave output from the carrier wave generation unit 23 and the modulated wave are compared, a three-phase PWM signal is generated, and the signal is output to the inverter 8 (S105).

By performing the processing in this way, a PWM signal is generated based on a carrier wave in which each waveform element corresponding to a plurality of types of periods is combined, so that it is possible to improve the audibility.

(Effect of PWM signal generation processing)
Next, the effect of the above-mentioned PWM signal generation processing will be described with reference to FIG. In FIG. 12, the vertical axis represents the intensity of the carrier sound and the horizontal axis represents the frequency. Then, FIG. 12 shows an example of the carrier sound characteristic (L1 in FIG. 12) in the reference example and the carrier sound characteristic (L2 in FIG. 12) in the present embodiment. The reference example is a case where a PWM signal is generated based on a carrier wave when the same waveform is repeated at a fixed cycle.

As shown in FIG. 12, in the reference example (L1 in FIG. 12), since the carrier wave repeats the same waveform in a fixed cycle, the carrier sound protrudes at the frequency f1 corresponding to the cycle. That is, the carrier sound of a specific frequency f1 is in a loud state, and there is a possibility that the audibility may be deteriorated.

On the other hand, in the present embodiment (L2 in FIG. 12), since a carrier wave in which each waveform element corresponding to a plurality of types of periods is combined is used, the intensity characteristic of the carrier sound can be diffused in the frequency domain. can. Specifically, as shown in FIG. 12, the convex points where the carrier sound becomes loud can be dispersed to a plurality of frequencies (f2, f3, f4, f5). Therefore, it is possible to suppress the protrusion of the carrier sound of a specific frequency, and it is possible to improve the audibility.

As described above, according to the inverter control device, the inverter control method, and the inverter control program according to the present embodiment, the carrier wave for generating the PWM signal is composed of a combination of a plurality of waveform elements having different periods. Therefore, the carrier sound, which is an electromagnetic noise generated due to the frequency of the carrier wave, can be frequency-diffused. That is, it is possible to suppress the generation of a large carrier sound at a specific frequency. Therefore, it is possible to improve the hearing sensation. Further, the motor driven by the inverter 8 may cause a resonance operation according to the rotation speed depending on the carrier period of the carrier wave. However, since the carrier period is set based on the rotation speed of the motor, the resonance It is possible to suppress the generation of roaring noise due to movement.

[Second Embodiment]
Next, the inverter control device, the inverter control method, and the inverter control program according to the second embodiment of the present disclosure will be described.
In the present embodiment, the carrier wave is configured in consideration of the generation time of each waveform element. Hereinafter, the inverter control device, the inverter control method, and the inverter control program according to the present embodiment will be mainly described with respect to differences from the first embodiment.

In the present embodiment, the carrier wave generation unit 23 generates a carrier wave configured to equalize the generation time of each waveform element. For example, when the waveform elements are provided corresponding to 3.15 kHz (fa), 4 kHz (fb), 5 kHz (fc), 6.3 kHz (fd), and 8 kHz (fe), one cycle of each waveform element is provided. The time is 0.317 msec, 0.25 msec, 0.2 msec, 0.159 msec, and 0.125 msec, respectively. In this way, the lower the frequency, the longer the period, so the ratio of the generation time of each waveform element is 30.2%, 23.8%, 19.0%, 15.1%, and 11.9%, respectively. .. That is, when the number of times of each waveform element is used equally, the intensity of the carrier sound caused by the waveform element corresponding to the low frequency may be relatively larger than the carrier sound caused by the other waveform elements. There is. Therefore, in the generation of the carrier wave, the frequency dispersion effect can be further improved by configuring the generation time of each waveform element to be equalized.

Therefore, the carrier wave generation unit 23 uses the generation probability in which the probability is set based on the frequency corresponding to each waveform element, and combines each waveform element to generate a carrier wave. The frequency corresponding to each waveform element is the reciprocal of the period corresponding to each waveform element. That is, the carrier wave generation unit 23 combines a plurality of waveform elements having different periods to form a waveform corresponding to the carrier period based on the generation probability, and generates a carrier wave composed by repeating the waveform. That is, the waveform elements included in the waveform for one cycle of the carrier wave are combined based on the probability of occurrence. In other words, the generation time of each waveform element is equalized in the waveform for one cycle, and the generation time of each waveform element is also equalized in the carrier wave as a whole.

Specifically, in the carrier wave generation unit 23, the generation probability is set for each waveform element so that the frequency corresponding to each waveform element and the probability have a positive correlation. That is, the higher the frequency of the waveform element, the higher the probability of occurrence is set. When setting the probability of occurrence so as to have a positive correlation, for example, the probability may be set in proportion to the frequency, or the probability may be set in proportion to the square root of the frequency. , The probability may be set in proportion to the square of the frequency. That is, if the probability is set to increase as the frequency increases, the method of setting the probability of occurrence is not limited.

FIG. 13 shows an example in which the occurrence probability is set so that the frequency and the probability have a positive correlation. In FIG. 13, the probability is set in proportion to the frequency (S1), the probability is set in proportion to the square root of the frequency (S2), and the probability is set in proportion to the square of the frequency (S3). ) Is shown. In this way, by setting the generation probability so that the probability increases as the frequency increases, the generation time of each waveform element is equalized.

For example, the probability of occurrence of 3.15 kHz (fa) is 10% (probability of occurrence is 2), the probability of occurrence of 4 kHz (fb) is 15% (probability of occurrence is 3), and the probability of occurrence of 5 kHz (fc) is 20% (occurrence). The ratio is set to 4), the probability of occurrence of 6.3 kHz (fd) is set to 25% (the probability of occurrence is 5), the probability of occurrence of 8 kHz (fe) is set to 30% (the probability of occurrence is 6), and so on. FIG. 14 shows a configuration example of a carrier wave when the generation probability is set as described above. Note that FIG. 14 is a configuration example of a waveform for one cycle of the carrier wave. By forming the carrier wave based on the generation probability, the generation time of each waveform element is equalized as shown in FIG. Therefore, the frequency dispersion effect is improved.

In this way, the carrier wave generation unit 23 generates a carrier wave by combining each waveform element based on the set generation probability. By generating the carrier wave based on the generation probability, the generation time of each waveform element is equalized, and the frequency dispersion effect is improved.

As described above, according to the inverter control device, the inverter control method, and the inverter control program according to the present embodiment, the carrier wave is configured to equalize the generation time of each waveform element, so that a specific period is specified. It is possible to prevent the carrier sound of the (frequency) from appearing more frequently and the carrier sound of the frequency from protruding. That is, it is possible to equalize the loudness of the carrier sound corresponding to the frequency of each waveform element and enhance the frequency diffusion effect. Therefore, it is possible to improve the hearing sensation.

In addition, the carrier wave uses the probability of occurrence in which the probability is set based on the frequency corresponding to each waveform element, and by combining each waveform element, the frequency of appearance of the waveform element having a specific period (frequency) becomes high. , It is possible to prevent the carrier sound of the frequency from protruding. That is, it is possible to equalize the loudness of the carrier sound corresponding to the frequency of each waveform element and enhance the frequency diffusion effect.

[Third Embodiment]
Next, the inverter control device, the inverter control method, and the inverter control program according to the third embodiment of the present disclosure will be described.
In the above-described first embodiment, the carrier wave is formed by combining the waveform elements for one cycle, but in the present embodiment, the carrier wave is formed in consideration of the rising edge and the falling edge. Hereinafter, the inverter control device, the inverter control method, and the inverter control program according to the present embodiment will be mainly described with respect to differences from the first embodiment. It should be noted that this embodiment can be combined with the second embodiment.

The carrier wave generation unit 23 in the present embodiment generates a carrier wave by using a deformed waveform element composed of rising and falling waveform elements having different periods. That is, the carrier wave generation unit 23 uses a deformed waveform element configured by using the rising edge of the waveform element of a certain period and the falling edge of the waveform element of another period in addition to each of the above-mentioned waveform elements. Generate waves. In other words, the carrier wave is composed of a combination of each waveform element and the generated modified waveform element. For example, the deformed waveform element is composed of a rising edge of a 3.15 kHz (fa) waveform element and a falling edge of an 8 kHz (fe) waveform element.

FIG. 15 shows a configuration example of a carrier wave in this embodiment. As shown in FIG. 15, the carrier wave is composed of a waveform element having a constant period and a deformed waveform element. Specifically, W1 and W2 are deformed waveform elements, and W3, W4, and W5 are waveform elements. W3 corresponds to 5 kHz (fc), W4 corresponds to 6.3 kHz (fd), and W5 corresponds to 8 kHz (fe). W1 corresponds to the rising edge of the waveform element having a rising edge of 3.15 kHz (fa) and the falling edge of the waveform element having a falling edge of 8 kHz (fe). W2 corresponds to the rising edge of the waveform element having a rising edge of 4 kHz (fb), and corresponds to the falling edge of the waveform element having a falling edge of 8 kHz (fe). The period of the carrier wave is T5.

In this way, the frequency dispersion effect can be enhanced by making the rising edge and the falling edge correspond to the waveform elements having different periods. Further, it is also possible to equalize the generation time of each waveform element (frequency) by configuring the rise and fall of the deformed waveform element based on the occurrence probability described in the second embodiment. Further, the rising edge and the falling edge of the deformed waveform element may be configured based on the occurrence probability described in the fourth embodiment described later.

As described above, according to the inverter control device, the inverter control method, and the inverter control program according to the present embodiment, a carrier wave is used by using a deformed waveform element composed of rising and falling waveform elements having different periods. By generating the above, it is possible to enhance the frequency diffusion effect and improve the audibility.

[Fourth Embodiment]
Next, the inverter control device, the inverter control method, and the inverter control program according to the fourth embodiment of the present disclosure will be described.
In the present embodiment, the probability of occurrence is set in consideration of the resonance characteristics of the structure. Hereinafter, the inverter control device, the inverter control method, and the inverter control program according to the present embodiment will be mainly described with respect to differences from the first embodiment. It should be noted that this embodiment can be combined with the second embodiment and / or the third embodiment.

When a carrier sound is generated at a specific frequency and the frequency matches or is close to the resonance point (natural frequency) of a structure provided on the output side of an inverter 8 such as a compressor, the carrier sound is heard prominently. There is a possibility that it will end up. For example, when the natural frequency of the compressor is 4 kHz (fb), the carrier sound of 4 kHz (fb) may be conspicuous even if the number of occurrences of the waveform element corresponding to 4 kHz (fb) is small. be.

Therefore, in the carrier wave generation unit 23 in the present embodiment, each waveform element is combined according to the generation probability set based on the resonance characteristics of the structure (for example, the compressor) provided on the output side of the inverter 8. Generates carrier waves. That is, based on the resonance characteristics of the structure, the probability of occurrence is set low for the waveform elements corresponding to or close to the resonance frequency (a predetermined bandwidth including the resonance frequency).

FIG. 16 is a diagram showing an example of resonance characteristics (sweep characteristics). In FIG. 16, the vertical axis represents the intensity of the carrier sound (sound pressure level), the horizontal axis represents the frequency, and the resonance characteristics (C1 in FIG. 16) are shown. Further, in FIG. 16, the vertical axis represents the probability, and the probability of occurrence corresponding to the resonance characteristic (P1 in FIG. 16) is shown.

In the example of FIG. 16, fc1, fc2, fc3, and fc4 are resonance frequencies, and the intensity of the carrier sound is high. When the generation probability is set corresponding to such a resonance characteristic, it becomes P1 in FIG. That is, the probability of occurrence is set so that the probability of occurrence of a frequency whose intensity increases according to the resonance characteristic decreases.

In this way, by setting the generation probability based on the resonance characteristics and combining each waveform element based on the set generation probability to generate a carrier signal, the carrier sound of a specific frequency is more effectively projected. Can be suppressed. That is, it is possible to more efficiently diffuse the frequency in consideration of the resonance characteristic and further improve the audibility.

As described above, according to the inverter control device, the inverter control method, and the inverter control program according to the present embodiment, it is possible to set a low frequency generation probability at which resonance is likely to occur due to the resonance characteristics, and it is specified by resonance. It is possible to suppress the protrusion of the carrier sound of the frequency of. In addition, it is possible to enhance the frequency diffusion effect and improve the audibility.

The present disclosure is not limited to the above-described embodiment, and various modifications can be made without departing from the gist of the invention. It is also possible to combine each embodiment. That is, the above-mentioned first embodiment, second embodiment, third embodiment, and fourth embodiment can be combined with each other.

For example, in each embodiment, the case where the compressor motor 9 is driven by using the inverter 8 has been described, but the target to which the inverter 8 is driven is not limited to the above. Along with this, it becomes possible to appropriately set the waveform element and the generation probability in consideration of the resonance characteristic of the target structure driven by the inverter 8.

The inverter control device, the inverter control method, and the inverter control program described in each of the above-described embodiments are grasped as follows, for example.
The inverter control device (20) according to the present disclosure is a carrier in which a setting unit (25) that sets a carrier period based on the rotation speed of a motor driven by the inverter (8) and a plurality of waveform elements having different periods are combined. PWM for the inverter (8) by a comparison method using a carrier wave generator (23) that forms a waveform corresponding to the period and generates a carrier wave composed of repeating waveforms, and a carrier wave and a predetermined modulated wave. A PWM signal generation unit (22) for generating a signal is provided. The specific waveform shape of the waveform element is, for example, a triangular wave, but it may be a sawtooth wave or the like, and is not limited to the triangular wave.

According to the inverter control device (20) according to the present disclosure, since the carrier wave for generating the PWM signal is composed of a combination of a plurality of waveform elements having different periods, it is generated due to the frequency of the carrier wave. Carrier sound, which is electromagnetic noise, can be frequency-diffused. That is, it is possible to suppress the generation of a large carrier sound at a specific frequency. Therefore, it is possible to improve the hearing sensation. Further, the motor driven by the inverter (8) may cause a resonance operation according to the rotation speed depending on the carrier cycle of the carrier wave. However, since the carrier cycle is set based on the rotation speed of the motor, the motor cycle is set based on the rotation speed of the motor. It is possible to suppress the generation of roaring sound due to the resonance operation.

In the inverter control device (20) according to the present disclosure, in the setting unit (25), the ratio between the period of the current fundamental wave component flowing through the motor according to the rotation speed and the carrier period is within a predetermined numerical range including an integer. Set the carrier cycle so that it does not become.

According to the inverter control device (20) according to the present disclosure, the carrier period is set so that the ratio of the period of the current fundamental wave component flowing through the motor to the carrier period does not fall within a predetermined numerical range including an integer. , The ratio of the carrier period to the period of the current fundamental wave component or the ratio of the period of the current fundamental wave component to the carrier period is an integral multiple (or a multiple close to an integer), and it is possible to suppress the generation of roaring noise.

In the inverter control device (20) according to the present disclosure, the numerical range is a range obtained by adding or subtracting 0.3 to an integer.

According to the inverter control device (20) according to the present disclosure, the carrier cycle can be set more appropriately by setting the numerical range as a range obtained by adding or subtracting 0.3 to an integer.

The motor drive device (1) according to the present disclosure includes an inverter (8) for driving a compressor motor (9) and the above-mentioned inverter control device (20).

In the inverter control method according to the present disclosure, a step of setting a carrier cycle based on the rotation speed of a motor driven by the inverter (8) and a waveform corresponding to the carrier cycle are configured by combining a plurality of waveform elements having different cycles. It also has a step of generating a carrier wave composed of repeated waveforms and a step of generating a PWM signal for the inverter (8) by a comparison method using the carrier wave and a predetermined modulated wave.

The inverter control program according to the present disclosure configures a waveform corresponding to a carrier cycle by combining a process of setting a carrier cycle based on the rotation speed of a motor driven by the inverter (8) and a plurality of waveform elements having different cycles. Then, the computer is made to execute a process of generating a carrier wave composed of repeating waveforms and a process of generating a PWM signal for the inverter (8) by a comparison method using the carrier wave and a predetermined modulated wave.

1: Motor drive device
4: AC power supply 5: Rectifier circuit 6: Inductance part 7: Capacitor part 8: Inverter 9: Compressor motor 11: CPU
12: ROM
13: RAM
15: Communication unit 18: Bus 20: Inverter control device 21: Acquisition unit 22: PWM signal generation unit 23: Carrier wave generation unit 24: Current sensor 25: Setting unit 31: Command calculation unit 32: Modulation wave generation unit 33: Comparison Department

Claims (6)

A setting unit that sets the carrier cycle based on the rotation speed of the motor driven by the inverter,
A carrier wave generator that combines a plurality of waveform elements having different periods to form a waveform corresponding to the carrier period and generates a carrier wave composed by repeating the waveform.
A PWM signal generation unit that generates a PWM signal for the inverter by a comparison method using the carrier wave and a predetermined modulated wave.
Inverter control device equipped with. The setting unit sets the carrier period so that the ratio between the period of the current fundamental wave component flowing through the motor according to the rotation speed and the carrier period does not fall within a predetermined numerical range including an integer. The inverter control device according to claim 1. The inverter control device according to claim 2, wherein the numerical range is a range obtained by adding or subtracting 0.3 to the integer. The inverter that drives the compressor motor and
The inverter control device according to any one of claims 1 to 3.
Motor drive device. The process of setting the carrier cycle based on the rotation speed of the motor driven by the inverter, and
A step of forming a waveform corresponding to the carrier cycle by combining a plurality of waveform elements having different cycles to generate a carrier wave composed of repetition of the waveform, and a step of generating a carrier wave.
A step of generating a PWM signal for the inverter by a comparison method using the carrier wave and a predetermined modulated wave, and
Inverter control method with. The process of setting the carrier cycle based on the rotation speed of the motor driven by the inverter, and
A process of forming a waveform corresponding to the carrier period by combining a plurality of waveform elements having different periods and generating a carrier wave composed of repetition of the waveform.
A process of generating a PWM signal for the inverter by a comparison method using the carrier wave and a predetermined modulated wave, and
Inverter control program to make a computer execute.

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