Control device, system, and program

Abstract

To suppress the phenomenon that an electromagnetic noise generated due to switching operation tends to increase and become observable.SOLUTION: A control device according to one embodiment of the present invention is connected to at least three or more switching control devices that convert an AC signal to a DC signal and output the resulting signal, or convert a DC signal to an AC signal and output the resulting signal. The control device generates as many carrier frequencies as the number of a plurality of switching control devices. The control device rearranges the plurality of generated carrier frequencies in ascending or descending order, and calculates the difference between adjacent carrier frequencies regarding two adjacent carrier frequencies, respectively. When all of the calculated difference between a plurality of adjacent carrier frequencies is different, the control device sets one of the plurality of generated carrier frequencies as a carrier frequency for one of the plurality of switching control devices in order.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] An embodiment of the present invention relates to a control device, a system, and a program. [Background technology]

[0002] In recent years, power generation methods using renewable energy such as solar power generation and wind power generation have become widespread. Accordingly, it has become common to install a large number of power conditioners (PCS: Power Conditioning Subsystems) within a certain range, each of which includes an inverter circuit for converting DC voltage generated using renewable energy into AC voltage.

[0003] However, the inverter circuit included in the above-mentioned PCS generates electromagnetic noise due to switching operation. If many such inverter circuits are provided within a certain area, the electromagnetic noise generated by each inverter circuit will interfere with each other and reinforce each other. For this reason, it is desirable to realize a new technology that can suppress the increase in electromagnetic noise caused by such a phenomenon and prevent it from being observed. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Patent No. 6211336 [Patent Document 2] Patent No. 6420186 Summary of the Invention [Problem to be solved by the invention]

[0005] An object of the present invention is to provide a control device, a system, and a program that can suppress the increase in electromagnetic noise generated in conjunction with switching operations from being observed. [Means for solving the problem]

[0006] A control device according to one embodiment is a switching control device that converts an AC signal into a DC signal and outputs the DC signal, or converts a DC signal into an AC signal and outputs the AC signal, and is connected to at least three or more switching control devices. The control device generates carrier frequencies in the same number as the switching control devices. The control device sorts the generated carrier frequencies in ascending or descending order, and calculates the adjacent carrier frequency difference between two adjacent carrier frequencies. When the calculated adjacent carrier frequency differences are all different, the control device sets one of the generated carrier frequencies as the carrier frequency of one of the switching control devices in turn. [Brief description of the drawings]

[0007] [Figure 1] FIG. 1 is a diagram illustrating an example of a schematic configuration of a switching system according to an embodiment. [Diagram 2] FIG. 2 is a diagram showing a detailed configuration of the switching control device according to the embodiment. [Diagram 3] FIG. 3 is a diagram showing a detailed configuration of a switching control unit included in the switching control device according to the embodiment. [Figure 4] FIG. 4 is a diagram for explaining the process of generating a PWM signal performed by the PWM signal generating unit shown in FIG. [Diagram 5] FIG. 5 is a flowchart showing an example of the operation of the central control device according to the embodiment. [Figure 6] FIG. 6 is a diagram for explaining the first comparative example. [Figure 7] FIG. 7 is a diagram for explaining the noise enhancement effect in the configuration according to the first comparative example. [Figure 8] FIG. 8 is a diagram for explaining the effect of the central control device according to the embodiment. [Figure 9] FIG. 9 is a diagram for explaining the noise enhancement effect in the configuration according to the embodiment. [Figure 10]FIG. 10 is a diagram for explaining another example of the operation of the central control device according to the embodiment. [Figure 11] FIG. 11 is a flowchart showing an example of the operation of the central control device according to the first modified example. [Figure 12] FIG. 12 is a diagram for explaining the second comparative example. [Figure 13] FIG. 13 is a flowchart showing an example of the operation of the central control device according to the second modified example. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0008] Hereinafter, an embodiment will be described with reference to the drawings. In addition, the disclosure is merely an example, and the invention is not limited to the contents described in the following embodiments. Modifications that a person skilled in the art can easily conceive are naturally included in the scope of the disclosure. In order to make the explanation clearer, the size, shape, etc. of each part may be changed from the actual embodiment and shown diagrammatically. In multiple drawings, corresponding elements may be given the same reference numerals, and detailed explanations may be omitted.

[0009] Fig. 1 is a diagram showing a schematic configuration example of a switching system 1 according to an embodiment. As shown in Fig. 1, the switching system 1 includes a plurality of switching control devices 2 and a central control device 3. The central control device 3 may be simply referred to as a control device. The number of switching control devices 2 included in the switching system 1 may be any number as long as it is at least three or more.

[0010] Each of the multiple switching control devices 2 includes a switching unit 4, and performs switching control by turning on and off the switching unit 4 in the device itself at a predetermined timing.

[0011] Each switching control device 2 is, for example, a power conversion device that converts a DC voltage generated by a renewable energy power generation device such as a photovoltaic (PV) device into an AC voltage. This type of power conversion device is also called a power conditioner (PCS: Power Conditioning Subsystem). Note that the power conversion device may have a mode in which a DC voltage is converted into an AC voltage (in other words, a mode in which a DC signal is converted into an AC signal) and a mode in which an AC voltage is converted into a DC voltage (in other words, a mode in which an AC signal is converted into a DC signal).

[0012] The central control device 3 is connected to a plurality of switching control devices 2 and controls the operations of the plurality of switching control devices 2. Specifically, the central control device 3 generates control parameters for each switching control device 2 regarding the timing at which the switching control device 2 performs a switching operation, and supplies (notifies) the control parameters to the switching control device 2. The control parameters may also be referred to as control information.

[0013] For example, the central control device 3 generates a first control parameter related to the timing at which one of the multiple switching control devices 2 performs a switching operation, and a second control parameter related to the timing at which another of the multiple switching control devices 2 performs a switching operation. The central control device 3 supplies the first control parameter to one of the multiple switching control devices 2 described above, and supplies the second control parameter to the other of the multiple switching control devices 2 described above.

[0014] One of the above-mentioned multiple switching control devices 2 performs switching control of the switching unit 4 in the own device based on a first control parameter supplied from the central control device 3. Similarly, another of the above-mentioned multiple switching control devices 2 performs switching control of the switching unit 4 in the own device based on a second control parameter supplied from the central control device 3.

[0015] 1 can be a noise source that generates electromagnetic noise because it performs switching operations. Here, let us assume that the value of electromagnetic noise generated and observed from one switching control device 2 in conjunction with the switching operation of that switching control device 2 is "1," and consider a situation in which N switching control devices 2 are arranged closely together.

[0016] In such a situation, for example, if the electromagnetic noise generated from each of the N switching control devices 2 is uncorrelated, the value of the electromagnetic noise generated and observed from each switching control device 2 will remain at "1."

[0017] On the other hand, in the above-mentioned situation, when the timings at which N switching control devices 2 perform their switching operations are the same, the electromagnetic noise itself generated from each switching control device 2 does not change, but the value of the electromagnetic noise generated from each switching control device 2 is emphasized "N times" depending on the position from which the electromagnetic noise is observed. Furthermore, when not only the timings at which N switching control devices 2 perform their switching operations but also the waveform shapes (frequency characteristics) of the electromagnetic noise generated from each switching control device 2 are the same, the value of the electromagnetic noise generated from each switching control device 2 and observed depending on the position from which the electromagnetic noise is observed is emphasized "N×N times".

[0018] In this way, when multiple noise sources are placed close to each other, the electromagnetic noises generated by each of the multiple noise sources may interfere with each other and reinforce each other. This phenomenon is called the "noise enhancement effect."

[0019] Therefore, the central control device 3 according to this embodiment controls the operation of each switching control device 2 so as to suppress the electromagnetic noise generated from each of the multiple switching control devices 2 from being amplified and observed due to the above-mentioned noise emphasis effect. Specifically, the central control device 3 generates different control parameters for each of the multiple switching control devices 2 connected to the central control device 3 (or multiple switching control devices 2 that may cause the noise emphasis effect) and supplies these to the switching control devices 2.

[0020] Fig. 2 is a diagram showing a detailed configuration of the switching control device 2 according to this embodiment. Note that the multiple switching control devices 2 shown in Fig. 1 all have the same configuration.

[0021] As shown in FIG. 2, the switching control device 2 includes a switching unit 4, a transformer 5, and a switching control unit 6.

[0022] The switching unit 4 has one or more switching elements, and includes, for example, a boost chopper circuit 4a and an inverter circuit 4b. The boost chopper circuit 4a converts the voltage amplitude of the input DC voltage. The inverter circuit 4b switches on and off the switching elements in its own circuit based on a PWM (Pulse Width Modulation) signal generated using a carrier signal and a reference signal, which will be described later, to generate an AC voltage. The elements included in the switching unit 4 are not limited to the boost chopper circuit 4a and the inverter circuit 4b described above, and may include other elements that perform DC / AC conversion, voltage, current, frequency, number of phases, and the like, while suppressing power loss. Specifically, the switching unit 4 may include a converter circuit.

[0023] The transformer 5 converts the voltage amplitude of the AC voltage to generate a commercial power supply voltage of, for example, 100V.

[0024] The switching control unit 6 performs switching control to turn on and off the switching unit 4 at a predetermined timing. In other words, the switching control unit 6 controls the operations of the step-up chopper circuit 4a and the inverter circuit 4b included in the switching unit 4.

[0025] The switching control unit 6 may be a semiconductor chip that performs digital signal processing such as a CPU (Central Processing Unit) or a DSP (Digital Signal Processor), or a discrete digital circuit component, or may be a semiconductor chip that performs analog signal processing or a discrete analog circuit component.

[0026] Fig. 3 is a diagram showing a detailed configuration of the switching control unit 6 included in the switching control device 2 according to this embodiment. As shown in Fig. 3, the switching control unit 6 includes a PWM signal generating unit 6a, a reference signal generating unit 6b, and a carrier signal generating unit 6c.

[0027] The PWM signal generating unit 6a generates a PWM signal for controlling the on / off of the switching unit 4. Although details will be described later, the PWM signal generating unit 6a generates the PWM signal by comparing the magnitude relationship between a reference signal generated by a reference signal generating unit 6b and a carrier signal generated by a carrier signal generating unit 6c.

[0028] The reference signal generating unit 6b generates a compensation value for making the AC voltage output from the switching unit 4 coincide with a target value, and generates a reference signal based on the compensation value. The generated reference signal is sent to the PWM signal generating unit 6a.

[0029] The carrier signal generating unit 6c generates a carrier signal based on the control parameters supplied from the central controller 3. More specifically, the carrier signal generating unit 6c generates a carrier signal having at least one of a frequency and a phase indicated by the control parameters supplied from the central controller 3. The generated carrier signal is sent to the PWM signal generating unit 6a.

[0030] In this embodiment, it is assumed that the control parameters supplied from the central control device 3 include a signal modulated with a carrier frequency, which is the frequency of the carrier signal. That is, it is assumed that the control parameters supplied from the central control device 3 indicate the carrier frequency. Note that the control parameters may indicate not only the carrier frequency but also the phase of the carrier signal as described above. Furthermore, the control parameters may further indicate, for example, the waveform shape and signal amplitude of the carrier signal, in addition to the carrier frequency and phase.

[0031] In addition, in this embodiment, it is assumed that the carrier signal generated by the carrier signal generating unit 6c is a triangular wave signal, but the carrier signal generated by the carrier signal generating unit 6c may have any waveform shape, such as a sawtooth wave signal, a sine wave signal, or a rectangular wave signal.

[0032] FIG. 4 is a diagram for explaining the process of generating a PWM signal performed by the PWM signal generating unit 6a shown in FIG.

[0033] The reference signal s1 generated by the reference signal generating unit 6b has a frequency approximately equal to the frequency (for example, 50 Hz to 60 Hz) of the AC voltage output from the switching unit 4. The carrier signal s2 generated by the carrier signal generating unit 6c is a signal having a frequency much higher than that of the reference signal s1, and is, for example, a triangular wave signal as described above.

[0034] For example, the PWM signal generating unit 6a sets the PWM signal to a high level when the signal amplitude of the reference signal s1 is greater than the signal amplitude of the carrier signal s2, and sets the PWM signal to a low level when the signal amplitude of the reference signal s1 is equal to or less than the signal amplitude of the carrier signal s2. As a result, a PWM signal s3 with a varying pulse width is generated as shown in FIG. 4. The generated PWM signal s3 is sent to the switching unit 4.

[0035] The switching unit 4 performs a switching operation of switching on and off one or more switching elements included in the switching unit 4 based on the PWM signal s3 from the PWM signal generating unit 6a.

[0036] The central control device 3 can control the pulse width of the PWM signal s3 by controlling at least one of the frequency and phase of the carrier signal s2. The central control device 3 according to this embodiment controls the frequency of the carrier signal s2 and controls the pulse width of the PWM signal s3, thereby controlling the timing at which electromagnetic noise is generated from the multiple switching control devices 2.

[0037] Fig. 5 is a flowchart showing an example of the operation of the central control device 3 according to this embodiment. Note that the series of operations shown in Fig. 5 is executed, for example, before the multiple switching control devices 2 connected to the central control device 3 start operating.

[0038] First, the central control device 3 generates carrier frequency values ​​(hereinafter simply referred to as "carrier frequencies") in the same number as the number of switching control devices 2 connected to the central control device 3, the carrier frequencies being within the range at which all of the switching control devices 2 connected to the central control device 3 can operate (or the carrier frequencies being within the range at which all of the switching control devices 2 that may cause a noise emphasis effect can operate) (step S1).

[0039] For example, the central control device 3 uses a random number generator to randomly generate carrier frequencies in the same number as the number of switching control devices 2. Note that the range of carrier frequencies within which all of the above-mentioned multiple switching control devices 2 can operate varies depending on, for example, the performance of the switching control devices 2.

[0040] Next, the central control device 3 rearranges the carrier frequencies generated in the processing of step S1 in ascending order (or descending order), and sequentially calculates the difference between two adjacent carrier frequencies (hereinafter referred to as the "difference between adjacent carrier frequencies") (step S2).

[0041] The central control device 3 checks whether the differences between the multiple adjacent carrier frequencies calculated in the process of step S2 are all different values ​​(step S3).

[0042] In the processing of step S3, if it is confirmed that the differences between the multiple adjacent carrier frequencies are not all different values, that is, at least two of the differences between the multiple adjacent carrier frequencies have the same value (No in step S3), the processing of step S1 described above is executed again, and carrier frequencies in the same number as the number of switching control devices 2 are again generated.

[0043] On the other hand, if it is confirmed in the process of step S3 that the differences between the multiple adjacent carrier frequencies are all different values ​​(Yes in step S3), the central control device 3 assigns each carrier frequency generated in the process of step S1 in order to the multiple switching control devices 2 connected to the central control device 3. Thereafter, the central control device 3 generates a control parameter indicating the assigned carrier frequency for each switching control device 2, and supplies this to the switching control device 2 (step S4), thereby completing this series of operations.

[0044] The central controller 3 may execute the series of operations shown in FIG. 5 at preset time intervals and update the control parameters supplied to each switching controller 2.

[0045] In addition, in the process of step S3 described above, it is confirmed whether the differences between the multiple adjacent carrier frequencies calculated in the process of step S2 are all different values, but the present invention is not limited to this, and for example, it may be acceptable that the differences between a predetermined percentage of the multiple adjacent carrier frequencies are the same, or that the differences between a predetermined number of the multiple adjacent carrier frequencies are the same. For example, when two of the multiple adjacent carrier frequency differences show the same value, the central control device 3 may accept this and execute the process of step S4 described above, and when three or more of the multiple adjacent carrier frequency differences show the same value, it may not accept this and execute the process of step S1 described above again.

[0046] In the following, the effects of the central control device 3 (including the switching system 1) according to this embodiment will be described using a first comparative example. Note that the first comparative example is intended to explain some of the effects that can be achieved by the central control device 3 according to this embodiment, and does not exclude effects common to this embodiment and the first comparative example from the scope of the present invention.

[0047] Fig. 6 is a diagram for explaining a first comparative example. In the first comparative example, it is assumed that carrier frequencies set so that the differences between adjacent carrier frequencies are all equal are assigned to four switching control devices 2_1 to 2_4 having the positional relationship shown in Fig. 6.

[0048] Specifically, the switching control device 2_1 adjacent to the switching control device 2_2 is assigned a carrier frequency f_1 of 3600 Hz. The switching control device 2_2 adjacent to the switching control devices 2_1, 2_3 is assigned a carrier frequency f_2 of 3630 Hz. The switching control device 2_3 adjacent to the switching control devices 2_2, 2_4 is assigned a carrier frequency f_3 of 3660 Hz. The switching control device 2_4 adjacent to the switching control device 2_3 is assigned a carrier frequency f_4 of 3690 Hz. That is, in the first comparative example, as shown in FIG. 6, it is assumed that the difference Δf_1_2 in the carrier frequencies assigned to the adjacent switching control devices 2_1, 2_2, the difference Δf_2_3 in the carrier frequencies assigned to the adjacent switching control devices 2_2, 2_3, and the difference Δf_3_4 in the carrier frequencies assigned to the adjacent switching control devices 2_3, 2_4 are all 30 Hz, and the differences in the adjacent carrier frequencies are all equal.

[0049] In this case, the four switching control devices 2_1 to 2_4 simultaneously radiate electromagnetic noise at relatively short intervals, generating a noise emphasis effect in a period that is the reciprocal of the greatest common divisor of the differences between adjacent carrier frequencies. Specifically, as shown in Fig. 7, the electromagnetic noises radiated from the switching control devices 2_1 to 2_4 interfere with each other and reinforce each other in a period of about 0.033 seconds (=1 / 30 Hz), generating a noise emphasis effect. Note that the horizontal axis of the graph shown in Fig. 7 indicates time, and the vertical axis indicates the square value of the time waveform n(t) of the electromagnetic noises radiated from the switching control devices 2_1 to 2_4.

[0050] In contrast, in the switching system 1 according to the present embodiment, as described above, carrier frequencies set so that the differences between adjacent carrier frequencies are all different can be assigned to the four switching control devices 2_1 to 2_4. Specifically, as shown in FIG. 8, 3600 Hz can be assigned as the carrier frequency f_1 to the switching control device 2_1, 3630 Hz can be assigned as the carrier frequency f_2 to the switching control device 2_2, 3647 Hz can be assigned as the carrier frequency f_3 to the switching control device 2_3, and 3687 Hz can be assigned as the carrier frequency f_4 to the switching control device 2_4. That is, in the present embodiment, carrier frequencies f_1 to f_4 set so that the differences Δf_1_2, Δf_2_3, and Δf_3_4 between adjacent carrier frequencies are all different can be assigned to the switching control devices 2_1 to 2_4, as shown in FIG. 8.

[0051] This makes it possible to lengthen the period during which the electromagnetic noises radiated from the switching control devices 2_1-2_4 interfere with each other and reinforce each other (i.e., the occurrence period of the noise emphasis effect) as compared to the first comparative example. Specifically, as shown in Fig. 9, the occurrence period of the noise emphasis effect can be set to one second, and the electromagnetic noise per unit time can be reduced.

[0052] Instead of executing the processes of steps S2 and S3 shown in FIG. 5, the central control device 3 according to the present embodiment may calculate all the differences between the carrier frequencies generated in the process of step S1 and execute a process to check whether all the calculated differences between the carrier frequencies are different values. That is, as shown in FIG. 10, the central control device 3 may check whether not only the differences Δf_1_2, Δf_2_3, Δf_3_4 between adjacent carrier frequencies, but also the differences between non-adjacent carrier frequencies (for example, the differences Δf_1_3, Δf_2_4, Δf_1_4 between the carrier frequencies shown in FIG. 10) among the carrier frequencies generated in the process of step S1 are different. According to this, it is possible to assign to the switching control device 2 carrier frequencies set so that all the differences between the carrier frequencies are different, and it is possible to obtain the same effect as the above-mentioned effect, or it is possible to lengthen the occurrence period of the noise emphasis effect and further reduce the electromagnetic noise per unit time.

[0053] Furthermore, the central control device 3 according to this embodiment may randomly generate carrier periods equal in number to the switching control devices 2 connected to the central control device 3 itself, instead of executing the process of step S1 shown in Fig. 5. In this case, the central control device 3 converts the generated carrier periods into carrier frequencies, and then executes the processes of steps S2 and S3 shown in Fig. 5. As a result, when it is confirmed that the differences between adjacent carrier frequencies are all different values, the central control device 3 generates control parameters indicating carrier periods corresponding to each carrier frequency, and supplies the control parameters to the switching control devices 2.

[0054] The following describes modified examples. (First Modification) Fig. 11 is a flowchart showing an example of the operation of the central control device 3 according to the first modified example. Note that the series of operations shown in Fig. 11 is executed, for example, before the multiple switching control devices 2 connected to the central control device 3 start operating.

[0055] First, the central control device 3 generates carrier frequencies within the range at which all of the multiple switching control devices 2 connected to the central control device 3 can operate (or, alternatively, generates carrier frequencies within the range at which all of the multiple switching control devices 2 that may cause a noise enhancement effect can operate), the number of carrier frequencies being equal to the number of these switching control devices 2 (step S11).

[0056] For example, the central control device 3 uses a random number generator to randomly generate carrier frequencies in the same number as the number of switching control devices 2. Note that the range of carrier frequencies within which all of the above-mentioned multiple switching control devices 2 can operate varies depending on, for example, the performance of the switching control devices 2.

[0057] Next, the central control device 3 rearranges the carrier frequencies generated in the process of step S11 in ascending order (or descending order), and sequentially calculates the differences between adjacent carrier frequencies (step S12).

[0058] The central control device 3 checks whether the differences between the multiple adjacent carrier frequencies calculated in the process of step S12 are all different values ​​(step S13).

[0059] In the processing of step S13, if it is confirmed that the differences between the multiple adjacent carrier frequencies are not all different values, that is, at least two of the differences between the multiple adjacent carrier frequencies have the same value (No in step S13), the processing of the above-mentioned step S11 is executed again, and carrier frequencies in the same number as the number of switching control devices 2 are generated again.

[0060] On the other hand, if it is confirmed in the processing of step S13 that the differences between the multiple adjacent carrier frequencies are all different values ​​(Yes in step S13), the central control device 3 checks whether there are any pairs of differences between the multiple adjacent carrier frequencies calculated in the processing of step S12 that have an integer multiple relationship (step S14).

[0061] In the processing of step S14, if it is confirmed that there is a pair of adjacent carrier frequencies that have an integer multiple relationship (No in step S14), the processing of step S11 described above is executed again, and carrier frequencies in the same number as the number of switching control devices 2 are generated again.

[0062] On the other hand, if it is confirmed in the process of step S14 that there is no pair of adjacent carrier frequencies having an integer multiple relationship (Yes in step S14), the central control device 3 assigns each of the carrier frequencies generated in the process of step S11 in order to the multiple switching control devices 2 connected to the central control device 3. Thereafter, the central control device 3 generates a control parameter indicating the assigned carrier frequency for each switching control device 2, and supplies this to the switching control device 2 (step S15), thereby completing this series of operations.

[0063] The central controller 3 may execute the series of operations shown in FIG. 11 at preset time intervals and update the control parameters supplied to each switching controller 2.

[0064] In the process of step S13 described above, it is confirmed whether the differences between the multiple adjacent carrier frequencies calculated in the process of step S12 are all different values, but the present invention is not limited to this, and for example, it may be acceptable that the differences between a predetermined percentage of the multiple adjacent carrier frequencies are the same, or that the differences between a predetermined number of the multiple adjacent carrier frequencies are the same. For example, when two of the multiple adjacent carrier frequency differences show the same value, the central control device 3 may accept this and execute the process of step S14 described above, and when three or more of the multiple adjacent carrier frequency differences show the same value, it may not accept this and execute the process of step S11 described above again.

[0065] Similarly, in the process of step S14 described above, it is confirmed whether there is any pair of adjacent carrier frequencies having an integer multiple relationship among the differences between the multiple adjacent carrier frequencies calculated in the process of step S12, but this is not limited thereto, and for example, it may be permitted that among the differences between the multiple adjacent carrier frequencies, a predetermined percentage of the differences between the multiple adjacent carrier frequencies have an integer multiple relationship, or that among the differences between the multiple adjacent carrier frequencies, a predetermined number of the differences between the multiple adjacent carrier frequencies have an integer multiple relationship. For example, if two of the differences between the multiple adjacent carrier frequencies have an integer multiple relationship, the central control device 3 may permit this and execute the process of step S15 described above, and if three or more of the differences between the multiple adjacent carrier frequencies have an integer multiple relationship, it may not permit this and execute the process of step S11 described above again.

[0066] In the following, the effects of the central control device 3 (including the switching system 1) according to this modified example will be described using a second comparative example. Note that the second comparative example is intended to explain some of the effects that can be achieved by the central control device 3 according to this modified example, and does not exclude effects common to this modified example and the second comparative example from the scope of the present invention.

[0067] Fig. 12 is a diagram for explaining a second comparative example. In the second comparative example, it is assumed that carrier frequencies are assigned to four switching control devices 2_1 to 2_4 having the positional relationship shown in Fig. 12 such that the differences between adjacent carrier frequencies are all different.

[0068] Specifically, 3600 Hz is assigned as the carrier frequency f_1 to the switching control device 2_1 adjacent to the switching control device 2_2. 3630 Hz is assigned as the carrier frequency f_2 to the switching control device 2_2 adjacent to the switching control devices 2_1, 2_3. 3690 Hz is assigned as the carrier frequency f_3 to the switching control device 2_3 adjacent to the switching control device 2_2, 2_4. 3780 Hz is assigned as the carrier frequency f_4 to the switching control device 2_4 adjacent to the switching control device 2_3. That is, in the second comparative example, as shown in FIG. 12, it is assumed that the difference Δf_1_2 between the carrier frequencies assigned to the adjacent switching control devices 2_1, 2_2 and the difference Δf_2_3 between the carrier frequencies assigned to the adjacent switching control devices 2_2, 2_3 have an integer multiple (in this case, 2 times) relationship. In addition, in the second comparative example, as shown in FIG. 12, it is assumed that the difference Δf_1_2 in the carrier frequencies assigned to adjacent switching control devices 2_1, 2_2 and the difference Δf_3_4 in the carrier frequencies assigned to adjacent switching control devices 2_3, 2_4 have an integer multiple (in this case, three times) relationship.

[0069] In this case, the four switching control devices 2_1 to 2_4 generate a noise emphasizing effect in a period of the reciprocal of the greatest common divisor of the differences between adjacent carrier frequencies. That is, in this case as well, similar to the case of Fig. 7 described above, the electromagnetic noises radiated from the switching control devices 2_1 to 2_4 interfere with each other and reinforce each other in a period of about 0.033 seconds, generating a noise emphasizing effect.

[0070] In contrast, in the switching system 1 according to this modification, as described above, it is possible to assign carrier frequencies to the four switching control devices 2_1-2_4 such that not only are the differences between adjacent carrier frequencies all different, but also that there are no pairs of adjacent carrier frequency differences that have an integer multiple relationship among the differences between the multiple adjacent carrier frequencies. This makes it possible to lengthen the period during which the electromagnetic noises radiated from the switching control devices 2_1-2_4 interfere with each other and reinforce each other (i.e., the occurrence period of the noise enhancement effect) compared to the second comparative example, and it is possible to reduce the electromagnetic noise per unit time.

[0071] 11, the central control device 3 according to this modification may randomly generate carrier periods equal in number to the switching control devices 2 connected to the central control device 3 itself. In this case, the central control device 3 converts the generated carrier periods into carrier frequencies, and then executes the processes of steps S12 to S14 shown in FIG. 11. As a result, when it is confirmed that the differences between adjacent carrier frequencies are all different values ​​and there is no pair of differences between adjacent carrier frequencies having an integer multiple relationship, the central control device 3 generates control parameters indicating carrier periods corresponding to each carrier frequency, and supplies the control parameters to the switching control devices 2.

[0072] (Second Modification) Next, a second modified example will be described. Fig. 13 is a flowchart showing an example of the operation of the central control device 3 according to the second modified example. Note that the series of operations shown in Fig. 13 is executed, for example, before a plurality of switching control devices 2 connected to the central control device 3 start operating.

[0073] First, the central control device 3 generates a carrier frequency within a range in which all of the multiple switching control devices 2 connected to the central control device 3 can operate (or a carrier frequency within a range in which all of the multiple switching control devices 2 that may cause a noise enhancement effect can operate) (step S21).

[0074] For example, the central control device 3 randomly generates one carrier frequency using a random number generator. Note that the carrier frequency range in which all of the above-mentioned multiple switching control devices 2 can operate varies depending on, for example, the performance of the switching control device 2.

[0075] Next, the central control device 3 sets an unused prime value as the difference between the adjacent carrier frequencies to generate a carrier frequency adjacent to one of the generated carrier frequencies (adjacent carrier frequency) (step S22). After that, the central control device 3 adds the difference between the adjacent carrier frequencies set in the process of step S22 to the carrier frequency generated in the process of step S21 to generate the above-mentioned adjacent carrier frequency (step S23).

[0076] Next, the central control device 3 checks whether or not the same number of carrier frequencies as the number of the switching control devices 2 connected to the central control device 3 have been generated (step S24).

[0077] If it is confirmed in the processing of step S24 that the same number of carrier frequencies as the number of switching control devices 2 connected to the device have not yet been generated (No in step S24), the adjacent carrier frequency generated in the processing of step S23 is used as a new carrier frequency, and the processing of the above-mentioned step S22 is executed again.

[0078] On the other hand, if it is confirmed in the process of step S24 that the same number of carrier frequencies as the number of switching control devices 2 connected to the central control device 3 have been generated (Yes in step S24), the central control device 3 assigns each of the carrier frequencies generated in the processes of steps S21 to S23 in order to the switching control devices 2 connected to the central control device 3. Thereafter, the central control device 3 generates a control parameter indicating the assigned carrier frequency for each switching control device 2, and supplies this to the switching control device 2 (step S25), thereby completing this series of operations.

[0079] The central controller 3 may execute the series of operations shown in FIG. 13 at preset time intervals and update the control parameters supplied to each switching controller 2.

[0080] Furthermore, the central control device 3 according to this modification may randomly generate one carrier cycle instead of executing the process of step S21 shown in Fig. 13. In this case, the central control device 3 converts the generated one carrier cycle into a carrier frequency, and then executes the processes of steps S22 to S24 shown in Fig. 13. As a result, when it is confirmed that the same number of carrier frequencies as the number of switching control devices 2 connected to the central control device 3 are generated, the central control device 3 generates control parameters indicating carrier cycles corresponding to each carrier frequency, and supplies the control parameters to the switching control devices 2.

[0081] The central control device 3 according to this modification can assign to a plurality of switching control devices 2 connected to the central control device 3 a carrier frequency that is set so that the differences between adjacent carrier frequencies are all different, there is no pair of differences between adjacent carrier frequencies that have an integer multiple relationship, and all the differences between adjacent carrier frequencies are prime numbers that have no positive common divisor other than 1. This makes it possible to lengthen the period in which electromagnetic noises radiated from the plurality of switching control devices 2 connected to the central control device 3 interfere with each other and reinforce each other (i.e., the occurrence period of the noise enhancement effect), and it is possible to reduce the electromagnetic noise per unit time.

[0082] In the present embodiment described above, it is assumed that the central control device 3 sets the carrier frequency of the switching control device 2 in units of 1 Hz, but the present invention is not limited to this, and the central control device 3 may set the carrier frequency of the switching control device 2 in finer units (for example, units of 0.1 Hz). This allows the reciprocal of the greatest common divisor of the differences between adjacent carrier frequencies to be larger than when the reciprocal is set in units of 1 Hz, making it possible to lengthen the occurrence period of the above-mentioned noise emphasis effect and further reduce electromagnetic noise per unit time.

[0083] According to the embodiment described above, it is possible to provide a control device, a system, and a program capable of suppressing the increase in electromagnetic noise generated by switching operations from being observed.

[0084] Although several embodiments of the present invention have been described, these embodiments are presented as examples and are not intended to limit the scope of the invention. These novel embodiments can be implemented in various other forms, and various omissions, substitutions, and modifications can be made without departing from the spirit of the invention. These embodiments and their modifications are included in the scope and spirit of the invention, and are included in the scope of the invention and its equivalents described in the claims. [Explanation of symbols]

[0085] 1...switching system, 2...switching control device, 3...central control device, 4...switching unit, 4a...boost chopper circuit, 4b...inverter circuit, 5...transformer, 6...switching control unit, 6a...PWM signal generating unit, 6b...reference signal generating unit, 6c...carrier signal generating unit.

Claims

1. A switching control device that converts an AC signal into a DC signal and outputs the DC signal, or converts a DC signal into an AC signal and outputs the DC signal, the switching control device being connected to at least three or more switching control devices, generating carrier frequencies equal in number to the plurality of switching control devices; rearrange the generated plurality of carrier frequencies in ascending or descending order, and calculate adjacent carrier frequency differences between two adjacent carrier frequencies; When the calculated differences between the adjacent carrier frequencies are all different, one of the generated carrier frequencies is set as a carrier frequency of one of the switching control devices in sequence. Control device.

2. when the calculated differences between the plurality of adjacent carrier frequencies are all different and there is no pair of differences between the plurality of adjacent carrier frequencies having an integer multiple relationship among the calculated differences between the plurality of adjacent carrier frequencies, set one of the generated plurality of carrier frequencies as a carrier frequency of one of the plurality of switching control devices in sequence; The control device according to claim 1 .

3. when the calculated differences between the adjacent carrier frequencies are all different and all of the calculated differences between the adjacent carrier frequencies are prime numbers, set one of the generated carrier frequencies as a carrier frequency of one of the switching control devices in sequence; The control device according to claim 1 .

4. Calculating all the differences between the generated plurality of carrier frequencies; When the calculated differences between the plurality of carrier frequencies are all different, one of the generated plurality of carrier frequencies is set in turn as a carrier frequency of one of the plurality of switching control devices. The control device according to claim 1 .

5. updating a carrier frequency set in each of the plurality of switching control devices at every preset time interval; The control device according to any one of claims 1 to 4.

6. A switching control device that converts an AC signal into a DC signal and outputs the DC signal, or converts a DC signal into an AC signal and outputs the DC signal, the switching control device being at least three or more switching control devices; a control device connected to the plurality of switching control devices; Equipped with The control device includes: generating carrier frequencies equal in number to the plurality of switching control devices; rearrange the generated plurality of carrier frequencies in ascending or descending order, and calculate adjacent carrier frequency differences between two adjacent carrier frequencies; When the calculated differences between the adjacent carrier frequencies are all different, one of the generated carrier frequencies is set as a carrier frequency of one of the switching control devices in sequence. system.

7. A switching control device that converts an AC signal into a DC signal and outputs the DC signal, or converts a DC signal into an AC signal and outputs the AC signal, the switching control device being connected to at least three or more switching control devices, and a program executed by the switching control device, The control device includes: generating a number of carrier frequencies equal to the number of the switching controllers; Sorting the generated plurality of carrier frequencies in ascending or descending order, and calculating adjacent carrier frequency differences between two adjacent carrier frequencies; When the calculated differences between the adjacent carrier frequencies are all different, setting one of the generated carrier frequencies as a carrier frequency of one of the switching control devices in sequence; A program for executing the above.

Images