Control device, inverter system, control method and program

Abstract

To provide a control device capable of reducing an amplitude of harmonics generated by switching of an inverter without changing a size of a filter when power is supplied from a power supply to an inverter using a two-phase modulation method.SOLUTION: A control device that controls an inverter that drives a load includes a first generation unit that generates a first signal for performing two-phase modulation when a three-phase AC voltage that drives the load is generated, an acquisition unit that acquires weight of the load, a storage unit that stores a correspondence relationship between the weight of the load and an amount of phase shift of the first signal, an identification unit that identifies the phase shift amount corresponding to the weight of the load acquired by the acquiring unit in the correspondence relationship, and a second generation unit that generates a second signal obtained by changing the phase shift amount from the first signal on the basis of the phase shift amount identified by the identification unit.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present disclosure relates to a control device, an inverter system, a control method, and a program. [Background technology]

[0002] Inverters that convert DC power to AC power are used in a variety of fields, including automobiles and other vehicles and home appliances. Patent Document 1 discloses a related technique, which is an inverter technique using a two-phase modulation method. The two-phase modulation method is a control method in which, during a certain period, the switching of a switching element corresponding to one of three phases is stopped, and the switching elements of the other two phases are switched so that the interphase voltages of the desired three-phase AC voltage are maintained. Note that a typical two-phase modulation method is one in which, for one phase near the peak of the desired three-phase AC voltage, the switching of a corresponding switching element is stopped, and the switching elements of the other two phases are switched so that the interphase voltages of the desired three-phase AC voltage are maintained. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2014-124024 A Summary of the Invention [Problem to be solved by the invention]

[0004] Other devices may be connected to the power supply that supplies DC power to the inverter. Furthermore, the current output by the power supply may have ripples. In this case, if the other devices have frequency characteristics that resonate with the frequency of the rippled current output by the power supply, malfunctions may occur in the other devices. For this reason, an LC filter consisting of an inductor L and a capacitor C may be used as a means to remove the ripple components.

[0005] Incidentally, in an inverter that generates three-phase AC power from DC power, the above-mentioned two-phase modulation method may be used to reduce losses due to switching. When using this two-phase modulation method, an LC filter may also be used. The inverter is composed of switching elements, and converts DC power into AC power by switching the switching elements between an on state and an off state. Therefore, if the frequency of the harmonics generated by the switching of the inverter is close to the resonant frequency of the LC filter, the amplitude of the harmonics may be amplified. In this case, by increasing at least one of the values ​​of the inductance of the inductor L and the capacitance of the capacitor C and lowering the resonant frequency of the LC filter, it is possible to distance the frequency of the harmonics generated by the switching of the inverter from the resonant frequency of the LC filter and to reduce the amplitude of the harmonics generated by the switching of the inverter. However, in general, in order to increase the inductance, it is necessary to increase the size of the inductor L. In addition, in general, in order to increase the capacitance, it is necessary to increase the size of the capacitor C. This goes against the demand for miniaturization in various fields such as vehicles such as automobiles and home appliances.

[0006] Therefore, when power is supplied from a power source to an inverter that uses two-phase modulation, there is a need for a technology that can reduce the amplitude of harmonics generated by inverter switching without changing the size of the filter.

[0007] The present disclosure has been made to solve the above-mentioned problems, and aims to provide a control device, inverter system, control method, and program that can reduce the amplitude of harmonics generated by inverter switching without changing the filter size when power is supplied from a power source to an inverter that uses a two-phase modulation method. [Means for solving the problem]

[0008] In order to solve the above problems, a control device according to the present disclosure is a control device that controls an inverter that drives a load, and includes a first generation unit that generates a first signal for performing two-phase modulation when a three-phase AC voltage that drives the load is generated, an acquisition unit that acquires the weight of the load, a memory unit that stores a correspondence relationship between the weight of the load and the phase shift amount of the first signal, an identification unit that identifies the phase shift amount that corresponds to the weight of the load acquired by the acquisition unit in the correspondence relationship, and a second generation unit that generates a second signal by changing the phase shift amount from the first signal based on the phase shift amount identified by the identification unit.

[0009] The inverter system according to the present disclosure includes a low-pass filter, an inverter that converts DC power into AC power, a power supply that supplies the DC power to the inverter via the low-pass filter, and the above-mentioned control device that controls the inverter.

[0010] A control method according to the present disclosure is a control method executed by a control device that controls an inverter that drives a load, and includes generating a first signal for performing two-phase modulation when a three-phase AC voltage that drives the load is generated, acquiring a weight of the load, storing a correspondence relationship between the weight of the load and a phase shift amount of the first signal, identifying the phase shift amount that corresponds to the acquired weight of the load in the correspondence relationship, and generating a second signal in which the phase shift amount is changed from the first signal based on the identified phase shift amount.

[0011] A program according to the present disclosure causes a computer controlling an inverter that drives a load to generate a first signal for performing two-phase modulation when a three-phase AC voltage that drives the load is generated, acquire a weight of the load, store a correspondence relationship between the weight of the load and a phase shift amount of the first signal, identify the phase shift amount that corresponds to the acquired weight of the load in the correspondence relationship, and generate a second signal in which the phase shift amount is changed from the first signal based on the identified phase shift amount. Effect of the Invention

[0012] According to the control device, inverter system, control method, and program disclosed herein, when power is supplied from a power source to an inverter that uses a two-phase modulation method, it is possible to reduce the amplitude of harmonics generated by the switching of the inverter without changing the size of the filter. [Brief description of the drawings]

[0013] [Figure 1] 1 is a diagram illustrating an example of a configuration of a motor drive device according to an embodiment of the present disclosure. [Diagram 2] FIG. 2 is a diagram illustrating an example of a configuration of a control device according to an embodiment of the present disclosure. [Diagram 3] FIG. 2 is a diagram illustrating an example of a desired three-phase AC voltage according to an embodiment of the present disclosure. [Figure 4] FIG. 2 is a diagram for explaining a first signal in an embodiment of the present disclosure. [Diagram 5] 11 is a diagram illustrating an example of a correspondence relationship between a load weight and a phase shift amount of a first signal in an embodiment of the present disclosure. FIG. [Figure 6] FIG. 1 is a first diagram showing an example of an experimental result according to an embodiment of the present disclosure. [Figure 7] FIG. 2 is a second diagram showing an example of an experimental result according to an embodiment of the present disclosure. [Figure 8] FIG. 4 is a diagram for explaining a second signal in an embodiment of the present disclosure. [Figure 9] FIG. 4 is a diagram illustrating an example of a processing flow of a control device 40 according to an embodiment of the present disclosure. [Figure 10] 11 is a diagram showing an example of a comparison result between an inverter current in a motor drive device according to an embodiment of the present disclosure and an inverter current in a related conventional motor drive device. FIG. [Figure 11] FIG. 1 is a schematic block diagram illustrating a configuration of a computer according to at least one embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0014] <Embodiment> Hereinafter, the embodiments will be described in detail with reference to the drawings. (Configuration of the motor drive device) A motor drive device according to an embodiment of the present disclosure will be described. Fig. 1 is a diagram showing a configuration of a motor drive device 1 (an example of an inverter system) according to an embodiment of the present disclosure. The motor drive device 1 is a device that can reduce the amplitude of harmonics generated by switching of an inverter that uses a two-phase modulation method without changing the size of a low-pass filter when power is supplied from a power source to the inverter.

[0015] 1, the motor drive device 1 includes a power supply 10, a first device 20, a second device 30, and a control device 40. The power supply 10 supplies DC power to the first device 20 and the second device 30.

[0016] The first device 20 includes a low-pass filter 201, an inverter 202, and a load 203. The low-pass filter 201 removes ripples in a current flowing from the inverter 202 to the power source 10. The low-pass filter 201 includes, for example, an inductor 2011 and a capacitor 2012. In this case, the low-pass filter 201 is an LC filter. The first device 20 is, for example, a compressor.

[0017] The inverter 202 generates a three-phase AC voltage for driving the load 203 under the control of the control device 40. As shown in FIG. 1, the inverter 202 includes switching elements 2021, 2022, 2023, 2024, 2025, and 2026. The switching elements 2021, 2022, 2023, 2024, 2025, and 2026 form a bridge circuit. The switching element 2021 is an element that forms an upper arm corresponding to the U phase of the three-phase AC voltage that drives the load 203. The switching element 2022 is an element that forms a lower arm corresponding to the U phase of the three-phase AC voltage. The switching element 2023 is an element that forms an upper arm corresponding to the V phase of the three-phase AC voltage. The switching element 2024 is an element that forms a lower arm corresponding to the V phase of the three-phase AC voltage. The switching element 2025 is an element that forms an upper arm corresponding to the W phase of the three-phase AC voltage. The switching element 2026 is an element that constitutes a lower arm corresponding to the W-phase of the three-phase AC voltage.

[0018] Examples of the switching elements 2021, 2022, 2023, 2024, 2025, and 2026 include an IGBT (Insulated Gate Bipolar Transistor) and a field effect transistor (FET). As shown in Fig. 1, a diode 2027 with an upper side as a cathode and a lower side as an anode is connected in parallel to each of the switching elements 2021, 2022, 2023, 2024, 2025, and 2026. The load 203 is, for example, a compressor motor (an example of a motor).

[0019] The second device 30 is a device different from the first device. The second device 30 is, for example, an inverter for driving a vehicle.

[0020] The control device 40 is a device that controls the inverter 202. The control device 40 includes a first generating unit 401, an acquiring unit 402, a storage unit 403, an identifying unit 404, and a second generating unit 405, as shown in FIG.

[0021] The first generating unit 401 generates a first signal sig1 for performing two-phase modulation when a three-phase AC voltage for driving the load 203 is generated. The first signal sig1 is a signal for stopping switching of a switching element of a corresponding one phase near the peak of the voltage or current of each of the three phases (for example, every time the electrical angle changes by 60 degrees) when the inverter 202 is controlled by the two-phase modulation method, and is a signal for switching the switching elements of the other two phases so that the inter-phase voltages of the desired three-phase AC voltage are maintained. FIG. 3 is a diagram showing an example of a desired three-phase AC voltage in an embodiment of the present disclosure. In FIG. 3, if it is assumed that 360 degrees returns to 0 degrees, the desired three-phase AC voltage has a downwardly convex peak for the W phase from 0 to 60 electrical degrees, a upwardly convex peak for the U phase from 60 to 120 degrees, a downwardly convex peak for the V phase from 120 to 180 degrees, a downwardly convex peak for the W phase from 180 to 240 degrees, a downwardly convex peak for the U phase from 240 to 300 degrees, and a upwardly convex peak for the V phase from 300 to 360 (i.e., 0) degrees.

[0022] Fig. 4 is a diagram for explaining the first signal sig1 in an embodiment of the present disclosure. If the three-phase AC voltage shown in Fig. 3 is a desired three-phase AC voltage, and 360 degrees in Fig. 4 is considered to return to 0 degrees, the first signal sig1 is the same as the control signal for realizing the on-duty shown in Fig. 4. That is, the first signal sig1 is the same as the control signal for making the on-duty of the W phase 0 percent at an electrical angle of 0 to 60 degrees, the on-duty of the U phase 100 percent at an electrical angle of 60 to 120 degrees, the on-duty of the V phase 0 percent at an electrical angle of 120 to 180 degrees, the on-duty of the W phase 100 percent at an electrical angle of 180 to 240 degrees, the on-duty of the U phase 0 percent at an electrical angle of 240 to 300 degrees, and the on-duty of the V phase 100 percent at an electrical angle of 300 to 360 (i.e., 0) degrees. Moreover, the first signal sig1 is the same as the control signal that always provides the same phase-to-phase voltage as the phase-to-phase voltage in the desired three-phase AC voltage.

[0023] The acquisition unit 402 acquires the weight of the load 203. For example, when the load 203 is a compressor motor, the acquisition unit 402 acquires the rotation speed of the compressor motor.

[0024] The storage unit 403 stores the correspondence relationship between the weight of the load 203 and the phase shift amount of the first signal. FIG. 5 is a diagram showing an example of the correspondence relationship between the weight of the load 203 and the phase shift amount of the first signal in an embodiment of the present disclosure. Note that FIG. 5 shows the correspondence relationship between the weight of the load 203 and the phase shift amount of the first signal in a case where the load 203 is a compressor motor and the weight of the load 203 is the rotation speed. A typical two-phase modulation method stops the switching of a corresponding switching element for one phase near the peak of a desired three-phase AC voltage, and switches the switching elements of the other two phases so that the inter-phase voltage of the desired three-phase AC voltage is maintained. However, an experiment has shown that by changing the timing for stopping the switching of the switching elements, the inverter current flowing from the inverter 202 to the power source 10 and the second device 30 is reduced, and as a result, the amplitude of the current harmonics is also reduced. FIG. 6 is a first diagram showing an example of an experimental result in an embodiment of the present disclosure. FIG. 7 is a second diagram showing an example of an experimental result in an embodiment of the present disclosure. FIG. 6 shows the magnitude of the inverter current when the load 203 is relatively light (when the rotation speed of the compressor motor is low). FIG. 7 shows the magnitude of the inverter current when the load 203 is relatively heavy (when the rotation speed of the compressor motor is high). In FIG. 6 and FIG. 7, the vertical axis shows the magnitude of the inverter current. Also, the horizontal axis shows the phase shift amount of the first signal. From FIG. 6, it can be seen that when the load 203 is relatively light, the inverter current is reduced when the phase shift amount of the first signal is smaller (for example, about 30 degrees). From FIG. 7, it can be seen that when the load 203 is relatively heavy, the inverter current is reduced when the phase shift amount of the first signal is larger (for example, about 90 degrees). In other words, FIG. 5 shows the correlation between the weight of the load 203 and the phase shift amount of the first signal at which the inverter current is reduced, which was obtained by an experiment. As shown in FIG. 5, in the region from where the load 203 is relatively light to where the load 203 is relatively heavy, the phase shift amount of the first signal by which the inverter current is reduced is approximately proportional to the weight of the load 203.

[0025] The identifying unit 404 identifies the amount of phase shift of the first signal corresponding to the weight of the load 203 acquired by the acquiring unit 402 in the correspondence relationship stored in the storage unit 403. For example, when the weight of the load 203 acquired by the acquiring unit 402 is the rotation speed A, the identifying unit 404 identifies the amount of phase shift B corresponding to the rotation speed A in the correspondence relationship shown in FIG.

[0026] The second generating unit 405 generates a second signal sig2 by changing the phase shift amount from the first signal sig1 based on the phase shift amount identified by the identifying unit 404. For example, when the first signal sig1 is a signal that realizes a desired three-phase AC voltage by the on-duty shown in Fig. 4 and the phase shift amount B identified by the identifying unit 404 is 90 degrees, the second generating unit 405 generates a control signal that realizes the desired three-phase AC voltage by the waveform shown in Fig. 8 obtained by shifting the phase of the waveform shown in Fig. 4 by 90 degrees. 8, assuming that 360 degrees returns to 0 degrees, the second signal sig2 is a control signal that sets the W-phase on-duty to 0 percent when the electrical angle is 30 to 90 degrees, sets the U-phase on-duty to 100 percent when the electrical angle is 90 to 150 degrees, sets the V-phase on-duty to 0 percent when the electrical angle is 150 to 210 degrees, sets the W-phase on-duty to 100 percent when the electrical angle is 210 to 270 degrees, sets the U-phase on-duty to 0 percent when the electrical angle is 270 to 330 degrees, and sets the V-phase on-duty to 100 percent when the electrical angle is 330 to 30 degrees. Also, the second signal sig2 is a control signal that always obtains the same interphase voltage as the interphase voltage in the desired three-phase AC voltage.

[0027] Next, the processing of the motor drive device 1 according to an embodiment of the present disclosure will be described. Fig. 9 is a diagram showing an example of a processing flow of the inverter control device according to an embodiment of the present disclosure. Here, the processing of the control device 40 will be described with reference to Fig. 9. Note that it is assumed that the storage unit 403 stores a correspondence relationship between the weight of the load 203 and the phase shift amount of the first signal (for example, the correspondence relationship shown in Fig. 5).

[0028] The first generating unit 401 generates a first signal sig1 for performing two-phase modulation when a three-phase AC voltage for driving the load 203 is generated (step S1). The acquiring unit 402 acquires the weight of the load 203 (step S2). For example, when the load 203 is a compressor motor, the acquiring unit 402 acquires the rotation speed of the compressor motor.

[0029] The identifying unit 404 identifies the amount of phase shift of the first signal corresponding to the weight of the load 203 acquired by the acquiring unit 402 in the correspondence relationship stored in the storage unit 403 (step S3). For example, when the weight of the load 203 acquired by the acquiring unit 402 is the rotation speed A, the identifying unit 404 identifies the amount of phase shift B corresponding to the rotation speed A in the correspondence relationship shown in FIG.

[0030] The second generating unit 405 generates a second signal sig2 by changing the phase shift amount from the first signal sig1 based on the phase shift amount identified by the identifying unit 404 (step S4). For example, when the first signal sig1 is a signal that realizes a desired three-phase AC voltage by the on-duty shown in Fig. 4 and the phase shift amount B identified by the identifying unit 404 is 90 degrees, the second generating unit 405 generates a control signal that realizes a desired three-phase AC voltage by the waveform shown in Fig. 8, which is obtained by shifting the phase of the waveform shown in Fig. 4 by 90 degrees.

[0031] The motor drive device 1 according to an embodiment of the present disclosure has been described above. In the control device 40 of the motor drive device 1 according to an embodiment of the present disclosure, the first generation unit 401 generates a first signal sig1 for performing two-phase modulation when a three-phase AC voltage is generated to drive the load 203. The acquisition unit 402 acquires the weight of the load 203, and the identification unit 404 identifies the amount of phase shift of the first signal corresponding to the weight of the load 203 acquired by the acquisition unit 402 in the correspondence relationship stored in the storage unit 403. The second generation unit 405 generates a second signal sig2 by changing the amount of phase shift from the first signal sig1 based on the amount of phase shift identified by the identification unit 404.

[0032] In this way, when power is supplied from the power source 10 to the inverter 202 that uses a two-phase modulation method, the control device 40 can reduce the amplitude of harmonics generated by the switching of the inverter 202 without changing the size of the low-pass filter 201.

[0033] Fig. 10 is a diagram showing an example of a comparison result between the inverter current in the motor drive device 1 according to an embodiment of the present disclosure and the inverter current in a related conventional motor drive device. As shown in Fig. 10, the motor drive device 1 according to an embodiment of the present disclosure can reduce the inverter current regardless of the magnitude of the load 203, compared to the related conventional motor drive device.

[0034] In addition, the storage unit 403, other storage devices (including registers and latches), and other storage units in each embodiment of the present disclosure may be provided anywhere within a range where appropriate information is transmitted and received. Also, the storage unit 403, other storage devices (including registers and latches), and other storage units may be present in multiple locations within a range where appropriate information is transmitted and received, and data may be stored in a distributed manner.

[0035] It should be noted that the order of the processes in the embodiments of the present disclosure may be changed as long as appropriate processes are performed.

[0036] Although the embodiment of the present disclosure has been described, the above-mentioned control device 40 and other control devices may have a computer system inside. The above-mentioned process steps are stored in a computer-readable recording medium in the form of a program, and the above-mentioned process is performed by the computer reading and executing the program. Specific examples of computers are shown below.

[0037] 11 is a schematic block diagram showing the configuration of a computer according to at least one embodiment. As shown in FIG. 11, the computer 5 includes a CPU 6, a main memory 7, a storage 8, and an interface 9.

[0038] For example, the above-mentioned control device 40 and each of the other control devices are implemented in the computer 5. The operations of each of the above-mentioned processing units are stored in the storage 8 in the form of a program. The CPU 6 reads the program from the storage 8, loads it in the main memory 7, and executes the above-mentioned processing in accordance with the program. The CPU 6 also secures storage areas in the main memory 7 corresponding to each of the above-mentioned storage units in accordance with the program.

[0039] Examples of the storage 8 include a hard disk drive (HDD), a solid state drive (SSD), a magnetic disk, a magneto-optical disk, a compact disc read only memory (CD-ROM), a digital versatile disc read only memory (DVD-ROM), and a semiconductor memory. The storage 8 may be an internal medium directly connected to the bus of the computer 5, or an external medium connected to the computer 5 via an interface 9 or a communication line. In addition, when the program is distributed to the computer 5 via a communication line, the computer 5 that receives the program may load the program into the main memory 7 and execute the above-mentioned process. In at least one embodiment, the storage 8 is a non-transitory tangible storage medium.

[0040] The program may also realize some of the functions described above. Furthermore, the program may be a file that can realize the functions described above in combination with a program already recorded in the computer system, that is, a so-called differential file (differential program).

[0041] Although some embodiments of the present disclosure have been described, these embodiments are merely examples and do not limit the scope of the invention. Various additions, omissions, substitutions, and modifications may be made to these embodiments without departing from the spirit of the invention.

[0042] <Additional Notes> The control device (40), the inverter system (1), the control method, and the program according to each embodiment of the present disclosure can be understood, for example, as follows.

[0043] (1) A control device (40) according to a first aspect is a control device (40) that controls an inverter (202) that drives a load (203), and includes: a first generation unit (401) that generates a first signal for performing two-phase modulation when a three-phase AC voltage that drives the load (203) is generated; an acquisition unit (402) that acquires a weight of the load (203); a memory unit (403) that stores a correspondence relationship between the weight of the load (203) and a phase shift amount of the first signal; an identification unit (404) that identifies the phase shift amount that corresponds to the weight of the load (203) acquired by the acquisition unit (402) in the correspondence relationship; and a second generation unit (405) that generates a second signal by changing the phase shift amount from the first signal based on the phase shift amount identified by the identification unit (404).

[0044] When power is supplied from a power source (10) to an inverter (202) that uses a two-phase modulation method, this control device (40) makes it possible to reduce the amplitude of harmonics generated by switching of the inverter (202) without changing the size of the filter (201).

[0045] (2) A control device (40) according to a second aspect is the control device (40) of (1), in which the load (203) is a motor, and the weight of the load (203) may be the rotation speed of the motor.

[0046] When power is supplied from a power source (10) to an inverter (202) that uses a two-phase modulation method, this control device (40) makes it possible to reduce the amplitude of harmonics generated by switching of the inverter (202) without changing the size of the filter (201).

[0047] (3) A control device (40) according to a third aspect is the control device (40) of (1) or (2), wherein the load (203) is a motor, and the correspondence relationship may indicate that the rotation speed of the motor and the amount of phase shift are proportional to each other.

[0048] The control device (40) can easily identify the motor rotation speed corresponding to the weight of the load (203).

[0049] (4) A control device (40) according to a fourth aspect is any one of the control devices (40) according to (1) to (3), wherein the load (203) is a motor, and the correspondence relationship may indicate that the phase shift amount is 90 degrees when the motor has a high rotation speed within an entire range of the rotation speed.

[0050] The control device (40) can identify an appropriate amount of phase shift when the load (203) is heavy.

[0051] (5) A control device (40) according to a fifth aspect is any one of the control devices (40) according to (1) to (4), wherein the load (203) is a motor, and the correspondence relationship may indicate that the phase shift amount is 30 degrees when the motor has a low rotation speed within an entire range of the rotation speed.

[0052] The control device (40) can identify an appropriate amount of phase shift when the load (203) is light.

[0053] (6) A control device (40) according to a sixth aspect is any one of the control devices (40) according to (1) to (5), and the amount of phase shift may be an amount converted into an electrical angle.

[0054] The control device (40) can specify an appropriate amount of phase shift taking into account the electrical angle.

[0055] (7) An inverter system (1) according to a seventh aspect includes a low-pass filter (201), an inverter (202) that converts DC power into AC power, a power source (10) that supplies the DC power to the inverter (202) via the low-pass filter (201), and a control device according to any one of the first to sixth aspects that controls the inverter (202).

[0056] With this inverter system, when power is supplied from a power source (10) to an inverter (202) that uses a two-phase modulation method, the amplitude of harmonics generated by switching of the inverter (202) can be reduced without changing the size of the filter (201).

[0057] (8) A control method according to an eighth aspect is a control method executed by a control device (40) that controls an inverter (202) that drives a load (203), and includes generating a first signal for performing two-phase modulation when a three-phase AC voltage that drives the load (203) is generated, acquiring a weight of the load (203), storing a correspondence relationship between the weight of the load (203) and a phase shift amount of the first signal, identifying the phase shift amount that corresponds to the acquired weight of the load (203) in the correspondence relationship, and generating a second signal in which the phase shift amount is changed from the first signal based on the identified phase shift amount.

[0058] With this control method, when power is supplied from a power source (10) to an inverter (202) that uses a two-phase modulation method, the amplitude of harmonics generated by switching of the inverter (202) can be reduced without changing the size of the filter (201).

[0059] (9) A program according to a ninth aspect causes a computer (5) that controls an inverter (202) that drives a load (203) to execute the following operations: generating a first signal for performing two-phase modulation when a three-phase AC voltage that drives the load (203) is generated; acquiring a weight of the load (203); storing a correspondence relationship between the weight of the load (203) and a phase shift amount of the first signal; identifying the phase shift amount that corresponds to the acquired weight of the load (203) in the correspondence relationship; and generating a second signal in which the phase shift amount is changed from the first signal based on the identified phase shift amount.

[0060] This program makes it possible, when power is supplied from a power source (10) to an inverter (202) that uses a two-phase modulation method, to reduce the amplitude of harmonics generated by switching of the inverter (202) without changing the size of the filter (201). [Explanation of symbols]

[0061] 1. Motor drive unit 5. Computers 6. CPU 7. Main memory 8. Storage 9. Interface 10...Power supply 20...1st device 30...Second device 40...Control device 201...Low pass filter 202...Inverter 203 Load 2021, 2022, 2023, 2024, 2025, 2026... Switching elements 401...1st generation section 402...Acquisition section 403...Storage section 404...Specific part 405...Second generation section

Claims

1. A control device for controlling an inverter that drives a load, a first generator that generates a first signal for performing two-phase modulation when a three-phase AC voltage for driving the load is generated; An acquisition unit that acquires the weight of the load; a storage unit configured to store a correspondence relationship between the weight of the load and an amount of phase shift of the first signal; an identification unit that identifies the amount of phase shift corresponding to the weight of the load acquired by the acquisition unit in the correspondence relationship; a second generator configured to generate a second signal by changing a phase shift amount from the first signal based on the phase shift amount specified by the specification unit; A control device comprising:

2. the load is a motor, The weight of the load is the rotation speed of the motor. The control device according to claim 1 .

3. the load is a motor, The correspondence relationship is The rotation speed of the motor and the phase shift amount are proportional to each other. The control device according to claim 1 or 2.

4. the load is a motor, The correspondence relationship is indicates that the phase shift amount is 90 degrees when the rotation speed of the motor is high within the entire range of the rotation speed of the motor; The control device according to any one of claims 1 to 3.

5. the load is a motor, The correspondence relationship is indicates that the phase shift amount is 30 degrees when the rotation speed of the motor is low within the entire range of the rotation speed of the motor; The control device according to any one of claims 1 to 4.

6. The phase shift amount is This is the amount converted into electrical angle. The control device according to any one of claims 1 to 5.

7. A low pass filter; An inverter that converts DC power into AC power; a power supply that supplies the DC power to the inverter through the low-pass filter; The control device according to any one of claims 1 to 6, which controls the inverter; An inverter system comprising:

8. A control method executed by a control device that controls an inverter that drives a load, comprising: generating a first signal for performing two-phase modulation when a three-phase AC voltage for driving the load is generated; obtaining a weight of the load; storing a correspondence relationship between the weight of the load and the phase shift amount of the first signal; Identifying the phase shift amount corresponding to the acquired weight of the load in the correspondence relationship; generating a second signal by changing a phase shift amount of the first signal based on the identified phase shift amount; A control method comprising:

9. The computer that controls the inverter that drives the load generating a first signal for performing two-phase modulation when a three-phase AC voltage for driving the load is generated; obtaining a weight of the load; storing a correspondence relationship between the weight of the load and the phase shift amount of the first signal; Identifying the phase shift amount corresponding to the acquired weight of the load in the correspondence relationship; generating a second signal by changing a phase shift amount of the first signal based on the identified phase shift amount; A program that executes the following.

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