Switch control device and power conversion device

Abstract

A switching control device (1) is provided with: a frequency setting unit (2) that sets a plurality of types of carrier frequencies and frequency change periods; and a control signal generation unit (4) as a control unit that controls the switching operation of the switching element by changing the plurality of types of carrier frequencies at a frequency change period. The frequency change period is set to be longer than a time width (window function width) determined by the reciprocal of the resolution bandwidth. Furthermore, fw is set so as to satisfy fave-RBW / 2lt, where fave is the average number of switching times in the frequency change period interval, fw is the average number of switching times in the interval cut out at the time width, RBW is the resolution bandwidth, and m is an integer of 2 or more; fwlt, fwlt; the relationship is fave + RBW / 2.

Description

Technical Field

[0001] This disclosure relates to a switch control device for controlling the switching action of a switching element and a power conversion device. Background Technology

[0002] In power conversion devices that perform power conversion based on the switching action of switching elements, electromagnetic noise is generated at a certain frequency and in the higher harmonic components of that frequency when switching is performed at a certain frequency. In products equipped with power conversion devices, a noise current standard is determined for each product category, and countermeasures are required when the noise current exceeds the upper limit of the standard. As a general countermeasure, a noise filter with noise reduction components such as choke coils or capacitors is considered; however, using such a noise filter leads to problems with the size of the device and increased cost. To improve this problem, a power conversion device has been proposed that includes: a frequency changing device that repeatedly outputs a frequency changing pattern containing multiple frequency values; and a controller that controls the switching of the switching element according to the switching frequency of the frequency changing pattern output from the frequency changing device (see, for example, Patent Document 1). Furthermore, a power conversion device that sets the period of the frequency changing pattern to achieve noise reduction effects under various measurement conditions and detection methods has also been proposed (see, for example, Patent Document 2).

[0003] Existing technical documents

[0004] Patent documents

[0005] Patent Document 1: Japanese Patent Application Publication No. 2006-288103

[0006] Patent Document 2: Japanese Patent Application Publication No. 2016-19322 Summary of the Invention

[0007] Previous power conversion devices have used multiple switching frequencies to reduce electromagnetic noise, but sometimes the noise reduction effect is not sufficient depending on the measurement conditions. Therefore, there is a need for technology that can achieve higher noise reduction effects for various measurement conditions.

[0008] This disclosure was made in view of the above circumstances, and its purpose is to provide a switching control device that can achieve a higher noise reduction effect for various measurement conditions.

[0009] In order to solve the above problems and achieve the object, the switching control device of the present disclosure is a switching control device that controls the switching operation performed by a switching element, and includes: a frequency setting unit that sets a plurality of types of carrier frequencies and a frequency change period; and a control unit that controls the switching operation performed by the switching element by changing the plurality of types of carrier frequencies at the frequency change period. The frequency change period is set to be longer than the time width determined by the reciprocal of the resolution bandwidth. Further, when the average number of switchings in the interval of the frequency change period is set to fave, the average number of switchings in the interval cut out by the time width is set to fw, the resolution bandwidth is set to RBW, and m is an integer of 2 or more, fw is set to satisfy the relationship fave - RBW / 2 < fw < fave + RBW / 2.

[0010] According to the switching control device related to the present disclosure, an effect can be obtained that a higher noise reduction effect can be obtained for various measurement conditions. BRIEF DESCRIPTION OF THE DRAWINGS

[0011] Figure 1 FIG. is a diagram showing the structure of the switching control device according to Embodiment 1. [[ID=eleven]]

[0012] Figure 2 FIG. is a first example of a time waveform of a switching rectangular wave for explaining a frequency change period.

[0013] Figure 3 FIG. is a second example of a time waveform of a switching rectangular wave for explaining a frequency change period.

[0014] Figure 4 FIG. is a diagram for explaining a method of calculating a spectrum in a short-time Fourier transform and an influence of a window function during calculation.

[0015] Figure 5 [[ID=2D]]

[0016] Figure 6 FIG. is for explaining based on Figure 5 FIG. shows a case of processing when performing a short-time Fourier transform on a switching rectangular wave based on the shown carrier frequency.

[0017] Figure 7 FIG. is a diagram for explaining an effect in the case of using the switching control device according to Embodiment 1.

[0018] Figure 8 FIG. is a diagram showing the structure of a DC-DC converter as a first example of a power conversion device using the switching control device according to Embodiment 1.

[0019] Figure 9 ​This is a diagram showing the structure of an inverter, which is a second example of a power conversion device using the switching control device according to Embodiment 1.

[0020] Figure 10 This is a diagram showing the structure of the switch control device according to Embodiment 2.

[0021] Figure 11 This is a diagram showing an example of the time waveform of the switching rectangular wave in Embodiment 2.

[0022] Figure 12 Regarding peak detection, a graph compares the frequency characteristics of electromagnetic noise when using the switched rectangular wave in Embodiment 2, the frequency characteristics of electromagnetic noise when using the switched rectangular wave with a fixed carrier frequency, and the frequency characteristics of electromagnetic noise when using the switched rectangular wave with only a variable carrier frequency.

[0023] Figure 13 The graph compares the frequency characteristics of electromagnetic noise when using the switched rectangular wave in Embodiment 2, the frequency characteristics of electromagnetic noise when using the switched rectangular wave with a fixed carrier frequency, and the frequency characteristics of electromagnetic noise when using the switched rectangular wave with only a variable carrier frequency, all related to average value detection.

[0024] Figure 14 This is a diagram showing an example of the time waveform of the switching rectangular wave used to illustrate Embodiment 2.

[0025] Figure 15 It is a diagram showing the phase of the composite vector of the two terms determined by the switching time of the first carrier frequency on the complex plane.

[0026] Figure 16 It is a diagram showing the phase of the composite vector of the two terms determined by the switching time of the second carrier frequency on the complex plane.

[0027] Figure 17 This is a diagram illustrating an example of the time waveform of the switching rectangular wave used to explain Embodiment 3.

[0028] Figure 18 It is shown on the complex plane Figure 17 The diagram shows the six phase differences.

[0029] Figure 19 This is a diagram illustrating an example of the time waveform of a switching rectangular wave with a variable frequency.

[0030] Figure 20 This is a diagram showing an example of the time waveform of a switching rectangular wave with a fixed frequency.

[0031] Figure 21Regarding peak detection, a graph compares the frequency characteristics of electromagnetic noise when using the switched rectangular wave in Embodiment 3, the frequency characteristics of electromagnetic noise when using the switched rectangular wave with a fixed carrier frequency, and the frequency characteristics of electromagnetic noise when using the switched rectangular wave with only a variable carrier frequency.

[0032] Figure 22 The graph compares the frequency characteristics of electromagnetic noise when using the switching rectangular wave in Embodiment 3, the frequency characteristics of electromagnetic noise when using the switching rectangular wave with a fixed carrier frequency, and the frequency characteristics of electromagnetic noise when using the switching rectangular wave with only a variable carrier frequency.

[0033] Figure 23 This is a diagram illustrating an example of a hardware structure for implementing the functions of the switch control device involved in embodiments 1-3.

[0034] Figure 24 This is a diagram illustrating another example of a hardware structure for implementing the functions of the switch control device according to embodiments 1-3. Detailed Implementation

[0035] Hereinafter, with reference to the accompanying drawings, the switch control device and power conversion device involved in the embodiments will be described in detail.

[0036] Implementation method 1.

[0037] Figure 1 This is a diagram showing the structure of the switch control device 1 according to Embodiment 1. The switch control device 1 is a device for controlling the switching operation of the switch element 5, and has a frequency setting unit 2, which sets multiple types of carrier frequencies and a frequency change period T as the period during which the carrier frequency changes. The switch element 5 is, for example, included in the power conversion circuit of a power conversion device.

[0038] The switch control device 1 also includes a control signal generation unit 4, which generates control signals to control the switching operation of the switch element 5 by changing multiple types of carrier frequencies with a frequency change period T. The control signal generation unit 4 is an example of a control unit. The frequency setting unit 2 sets multiple types of carrier frequencies in a way that reduces switching noise of higher harmonic components when the switch element 5 performs switching operation.

[0039] When the power conversion circuit is an inverter, the carrier frequency of a typical inverter often ranges from a few kHz to 20 kHz. Conversely, when the power conversion circuit is a DC-DC (Direct Current-to-Current) converter, a typical DC-DC converter often uses any value within a wide range from a few kHz to a few MHz.

[0040] Figure 2 This is a diagram illustrating the first example of a time waveform of a switching rectangular wave used for explaining the frequency variation period T. Figure 2 For simplicity, the carrier frequency types are 2, with f1 = 15kHz and f2 = 30kHz. The duty cycle D, the ratio of the on-time to the period of one cycle of the switching rectangular wave based on carrier frequencies f1 and f2, is set to D = 0.5. Additionally, Figure 3 This is a diagram of the second example of the time waveform of a switching rectangular wave used to illustrate the frequency variation period T. Figure 3 It is used with Figure 2 The comparison graph, in Figure 3 A fixed switching frequency f = 20kHz is used. Figure 2 as well as Figure 3 In the diagram, the horizontal axis represents time, and the vertical axis represents voltage.

[0041] When the frequency setting unit 2 sets two carrier frequencies, f1 = 15kHz and f2 = 30kHz, the control signal generation unit 4 outputs, for example,... Figure 2 The switch rectangular wave is shown. Furthermore, when the carrier frequency is fixed at a single f = 20kHz using the frequency setting unit 2, the control signal generator 4 outputs, for example, a rectangular wave. Figure 3 The switch rectangular wave is shown. In Figure 3 In the second example shown, the frequency change period T becomes T = 1 / f = 0.05 ms. On the other hand, in Figure 2 In the first example shown, regarding the control signal, the rectangular wave is not a switching rectangular wave with the on-time repeating at regular intervals, but rather a switching rectangular wave with the on-time repeating in relation to the reciprocals of two different carrier frequencies. Specifically, in Figure 2 In the first example shown, the frequency change period T is determined by the sum of the reciprocals of the various carrier frequencies, becoming T = 1 / f1 + 1 / f2 = 0.1 ms.

[0042] In the switch control device 1 according to Embodiment 1, at least two carrier frequencies are set. Furthermore, in Embodiment 1, the frequency change period T is set to be longer than the time width determined by the reciprocal of the resolution bandwidth (RBW). Moreover, the at least two carrier frequencies can be determined by taking into account some or all of the performance of the switching element 5, losses of passive components, hardware constraints such as thermal limits, and constraints of the microcomputer, or by comprehensively considering the influence of other frequency bands of higher harmonics.

[0043] Next, we will explain the relationship between various detection methods and noise reduction effects. Among the detection methods, there are peak detection, quasi-peak detection, and average value detection. Figure 4 This is a diagram used to illustrate the method for calculating the spectrum in the short-time Fourier transform and the influence of the window function during the calculation.

[0044] In short-time Fourier transforms used in EMI (Electromagnetic Interference) receivers, a portion of the time waveform acquired within a certain measurement time is cut out using a window function, and a Fast Fourier Transform (FFT) is performed to obtain the spectrum within that portion. By shifting the windowed portion bit by bit, multiple spectra are obtained. Extracting the peak values ​​from these multiple spectra yields the spectrum obtained in peak detection, and calculating the average value yields the spectrum obtained in average detection. Quasi-peak detection is a method of obtaining the spectrum by adding a time constant circuit to peak detection; it is essentially a method of extracting peak values. In the method of Embodiment 1 described below, the repetition period of the switch is sufficiently early relative to the time constant, so a spectrum approximately the same as that obtained in peak detection is obtained. Hereinafter, in this specification, peak detection and quasi-peak detection will be suitably referred to collectively as "peak detection."

[0045] The window width Tw, which is the time width of the window function, is determined by the reciprocal of the resolution bandwidth RBW, and takes various values ​​depending on the standard and frequency band being considered. Representative values ​​for the resolution bandwidth RBW include 200Hz, 1kHz, 9kHz, 10kHz, 120kHz, and 1MHz. For example, sometimes RBW = 200Hz is specified for frequency bands below 150kHz, and RBW = 9kHz (or 10kHz) is specified for frequency bands from 150kHz to 30MHz.

[0046] exist Figure 4The example shown is spectrum 1, spectrum 2, and spectrum 3, obtained by shifting intervals cut out using a window function bit by bit. In these three spectra 1-3, the frequency bands where the spectral values ​​increase are different. Therefore, as... Figure 4 As shown in the lower part, the spectrum differs significantly between detection performed in average value detection and detection performed in peak value detection, making it difficult to obtain noise reduction effects in peak value detection. Furthermore, evaluating the noise reduction effect in peak value detection requires meticulous management of the relationship between the window function position and the peak position of the spectrum, which makes it difficult to evaluate the noise reduction effect. Therefore, in Implementation 1, the method shown below is proposed.

[0047] Figure 5 This diagram illustrates the switch control using the switch control device 1 according to Embodiment 1. In a more detailed explanation, Figure 5 The diagram illustrates the time-varying nature of the carrier frequency. Figure 5 In this example, there are 4 types of carrier frequencies. The four carrier frequencies f1, f2, f3, and f4 are set as f1 = 49kHz, f2 = 39kHz, f3 = 50kHz, and f4 = 38kHz, respectively. The frequency change period T is set as T = 5ms. Figure 5 The horizontal axis represents time, and the vertical axis represents the carrier frequency.

[0048] like Figure 5 As shown, in the initial 2.5ms interval, the pattern f1, f1, f2, f2 is repeated; in the subsequent 2.5ms interval, the pattern f3, f3, f4, f4 is repeated. Then, the next 2.5ms interval returns to the f1, f1, f2, f2 pattern, and so on, until the next 2.5ms interval returns to the f3, f3, f4, f4 pattern. Therefore, the frequency change period T becomes 5ms.

[0049] Figure 6 It shows the basis Figure 5 The diagram illustrates the processing of a switched rectangular wave at the shown carrier frequency during short-time Fourier transform. With RBW = 9 kHz, the window function width Tw = 0.111 ms. Although calculations are omitted, the repetition period for modes f1, f2, and f2 is 0.0921 ms, and the repetition period for modes f3, f4, and f4 is 0.0926 ms. Therefore, as... Figure 6 As shown, a window function width Tw contains four switching rectangular waves. Since the frequency change period T = 5ms, there exists a relationship of T > Tw between the frequency change period T and the window function width Tw. That is, in Embodiment 1, the frequency change period T is set to be longer than the window function width Tw, which is the time width determined by the reciprocal of the resolution bandwidth RBW.

[0050] Here, using four carrier frequencies f1, f2, f3, and f4 Figure 5 In the case of the switch rectangular wave shown, the combination of intervals cut out by the window function width Tw becomes the following 14 patterns.

[0051] <Mode based on carrier frequencies f1 and f2>

[0052] (a1)f1, f1, f2, f2

[0053] (a2)f1, f2, f2, f1

[0054] (a3)f2, f2, f1, f1

[0055] (a4)f2、f1、f1、f2

[0056] <Modes based on carrier frequencies f3 and f4>

[0057] (a5)f3、f3、f4、f4

[0058] (a6)f3、f4、f4、f3

[0059] (a7)f4、f4、f3、f3

[0060] (a8)f4、f3、f3、f4

[0061] <Other Modes>

[0062] (a9)f1, f2, f2, f3

[0063] (a10)f2、f2、f3、f3

[0064] (a11)f2, f3, f3, f4

[0065] (a12)f3, f4, f4, f1

[0066] (a13)f4、f4、f1、f1

[0067] (a14)f4、f1、f1、f2

[0068] (a1)ˉ(a4) is in Figure 5 The pattern appears in the repeating intervals f1 and f2 of the initial 2.5ms interval. Figure 6The figure shows the spectrum 1 of the FFT of pattern (a1) using window function wf1, the spectrum 2 of the FFT of pattern (a4) using window function wf2, the spectrum 3 of the FFT of pattern (a2) using window function wf3, and the spectrum 4 of the FFT of pattern (a3) ​​using window function wf4. These intervals contain patterns where both f1 and f2 appear twice, and as shown in the figure, the same spectrum is obtained even when the window function width Tw is shifted.

[0069] Additionally, (a5)ˉ(a8) is in Figure 5 The patterns appearing in the repeating intervals of f3 and f4, following the initial 2.5ms interval, occur twice in these intervals. Therefore, in (a5)ˉ(a8), the same spectrum is obtained even if the window function width Tw is shifted. Additionally, (a9)ˉ(a11) are patterns that appear instantaneously when switching from the repeating intervals of f1 and f2 to the repeating intervals of f3 and f4, and (a12)ˉ(a14) are patterns that appear instantaneously when switching from the repeating intervals of f3 and f4 to the repeating intervals of f1 and f2. The spectra of these intervals are slightly different from those of (a1)ˉ(a4) or (a5)ˉ(a8), but as seen from... Figure 5 It is understandable that this is a pattern that temporarily appears within a frequency change period T = 5ms, and the proportion of occurrences within the frequency change period T is small, so it will not cause significant impact on spectrum calculations. Furthermore, as stated in this specification... Figure 5 For example, when the difference between the values ​​of f1 and f3 and the difference between the values ​​of f2 and f4 are set to be small, the effect of the spectral difference becomes minimal even at the instant of switching carrier frequency groups.

[0070] Figure 5 as well as Figure 6 The pattern shown is an example of the switching rectangular wave pattern in Embodiment 1. When generalizing the conditions of the switching rectangular wave pattern in Embodiment 1, it can be represented by the following equation (1A).

[0071] fave-RBW / 2 <fw<fave+RBW / 2…(1A)

[0072] In equation (1A) above, fave is the average number of switching operations within the interval of frequency variation period T, and fw is the average number of switching operations within the interval cut out by the window function width Tw. When using multiple types of carrier frequencies as in Embodiment 1, the average number of switching operations can be calculated by harmonic averaging of the multiple types of carrier frequencies. Furthermore, the concept of weighted harmonic averaging is also included in the harmonic averaging mentioned here.

[0073] In addition, the above formula (1A) can also be expressed as |fw - fave| < RBW / 2. The meaning of this formula is that the absolute value of the difference between the average number of switches fave in the interval of the frequency change period T and the average number of switches fw in the interval cut out by the window function width Tw is less than 1 / 2 of the resolution bandwidth RBW. It is sufficient to satisfy this condition and the condition that the above frequency change period T is longer than the window function width Tw which is the time width determined by the reciprocal of the resolution bandwidth RBW. If the switching rectangular wave in the control signal generated by the switching control device 1 satisfies these two conditions, the influence of the window function width Tw in the spectrum obtained by average value detection and the spectrum obtained by peak detection can be reduced.

[0074] Figure 7 is a diagram for explaining the effects in the case of using the switching control device 1 according to Embodiment 1. In Figure 7 ,"Conventional Method 1 (Fixed Frequency)" means using a switching rectangular wave with a fixed carrier frequency. Hereinafter, "Conventional Method 1 (Fixed Frequency)" will be simply referred to as "Conventional Method 1". In addition, "Proposed Method (Embodiment 1)" is the method of Embodiment 1 that switches two carrier frequencies in the two 2.5 ms intervals shown in Figure 5 . Hereinafter, "Proposed Method (Embodiment 1)" will be simply referred to as "Proposed Method". In addition, "Conventional Method 2 (Variable Frequency)" means using a pattern that alternately repeats f1 and f2 such as f1, f2, f1, f2,.... This method is positioned as an example of a general variable frequency method. Hereinafter, "Conventional Method 2 (Variable Frequency)" will be simply referred to as "Conventional Method 2".

[0075] In Figure 7 , at the upper left, the frequency characteristic of the noise current using average value detection in the case of using the proposed method is represented by a thick solid line, and the frequency characteristic of the noise current using average value detection in the case of using Conventional Method 1 is represented by a thin solid line. In addition, in Figure 7 , at the upper right, the frequency characteristic of the noise current using peak detection in the case of using the proposed method is represented by a thick solid line, and the frequency characteristic of the noise current using peak detection in the case of using Conventional Method 1 is represented by a thin solid line.

[0076] In addition, in Figure 7 , at the lower left, the frequency characteristic of the noise current using average value detection in the case of using Conventional Method 2 is represented by a thick solid line. In addition, for comparison, the characteristic curve based on Conventional Method 1 shown in the upper left is represented by a thin solid line. In Figure 7 , at the lower right, the frequency characteristic of the noise current using peak detection in the case of using Conventional Method 2 is represented by a thick solid line. In addition, for comparison, the characteristic curve based on Conventional Method 1 shown in the upper right is represented by a thin solid line. In addition, Figure 7 The horizontal axis represents frequency, and the vertical axis represents the noise current level.

[0077] If the recommended method is used, as described in the "Summary of the Invention" section, it is possible to "obtain a higher noise reduction effect for various measurement conditions." Here, as specific examples of "various measurement conditions," we envision (1) the case evaluated by both peak detection and average detection, and (2) the case evaluated under different RBW conditions. Generally, the resolution bandwidth RBW is determined for each frequency band to be measured. For example, as mentioned above, sometimes in the frequency band below 150kHz, RBW is determined to be 200Hz, and in the frequency band from 150kHz to 30MHz, RBW is determined to be 9kHz (or 10kHz). Figure 7 The values ​​of these RBWs were also used to determine the values ​​in each of the graphs. Observations were made from these perspectives. Figure 7 First, when comparing the recommended method and the conventional method 2, the noise reduction effect of peak detection remains the same, and under average detection, the recommended method achieves a higher noise reduction effect (around 1MHz). Therefore, from the viewpoint of (1), the recommended method achieves a better noise reduction effect. Furthermore, when comparing from the viewpoint of (2), in the frequency band from 150kHz to 30MHz with RBW = 9kHz, both the recommended method and the conventional method 2 achieve equivalent noise reduction effects. On the other hand, in the frequency band below 150kHz with RBW = 200Hz, the recommended method achieves a higher noise reduction effect (around 90kHz). This trend is consistent in both average detection and peak detection. Based on the above, the recommended method can achieve a "higher noise reduction effect for various measurement conditions" regardless of whether it is from the viewpoints of (1) or (2). Furthermore, in Figure 7 The example uses noise current for illustration, but the method described in this specification is not limited to the standard of noise current.

[0078] Figure 8 This diagram shows the structure of a DC-DC converter 10, which is a first example of a power conversion device using the switch control device 1 according to Embodiment 1. The DC-DC converter 10 has the aforementioned switch control device 1 and a boost chopper circuit 11 connected to a DC power supply 12 and a load 13. The boost chopper circuit 11 is an example of a power conversion circuit and includes a reactor 14, a switching element 15, a diode 16, and a smoothing capacitor 17.

[0079] The switching element 15 performs switching operations according to the timing of the control signal output from the control signal generator 4 of the switching control device 1. The boost chopper circuit 11 boosts the voltage of the input power from the DC power supply 12 to supply the load 13 with the desired output voltage. The switching element 15 uses a semiconductor switching element such as a MOSFET (Metal-Oxide Semiconductor Field-Effect Transistor) or an IGBT (Insulated Gate Bipolar Transistor) with diodes 16 connected in antiparallel.

[0080] In order to obtain the desired DC voltage, the DC-DC converter 10 changes the duty cycle of the switching rectangular wave in accordance with the state of the load 13.

[0081] The power conversion circuit can also be any circuit other than the boost chopper circuit 11, such as a buck chopper circuit.

[0082] Figure 9 This diagram shows the structure of an inverter 20, which is a second example of a power conversion device using the switch control device 1 according to Embodiment 1. The inverter 20 has the switch control device 1 according to Embodiment 1 and an inverter main circuit 21 connected to a DC power supply 22 and a load 23. The inverter main circuit 21 is an example of a power conversion circuit and has a switching element 24.

[0083] The switching element 24 performs switching operations according to the timing of the control signal output from the control signal generator 4 of the switching control device 1. The inverter main circuit 21 boosts the voltage of the input power from the DC power supply 22 to supply the desired AC output power to the load 23. The switching element 24 uses semiconductor switching elements such as MOSFETs or IGBTs with diodes connected in antiparallel.

[0084] The inverter main circuit 21, in conjunction with the pulse width modulation control used to apply the desired AC voltage of the inverter to the load 13, causes the duty cycle of the switching rectangular wave to change.

[0085] As described above, the switching control device according to Embodiment 1 is a switching control device that controls the switching operation of a switching element, and includes a frequency setting unit and a control unit. The frequency setting unit sets a plurality of types of carrier frequencies and a frequency change period, and the control unit controls the switching operation of the switching element by causing the plurality of types of carrier frequencies to change at the frequency change period. The frequency change period is set to be longer than the time width determined by the reciprocal of the resolution bandwidth. In addition, when the average number of switching operations in the interval of the frequency change period is set to fave, the average number of switching operations in the interval cut out by this time width is set to fw, the resolution bandwidth is set to RBW, and m is an integer of 2 or more, fw is set to satisfy the relationship of fave - RBW / 2 < fw < fave + RBW / 2. If the switching rectangular wave set in this way is used, the influence of the window function width in the spectrum obtained by average value detection and the spectrum obtained by peak detection can be reduced. Therefore, if the switching control device according to Embodiment 1 is used, a higher noise reduction effect can be obtained for various measurement conditions.

[0086] Embodiment 2.

[0087] Figure 10 FIG. is a diagram showing the configuration of the switching control device 1A according to Embodiment 2. In comparison Figure 10 and Figure 1 when, in Figure 10 the switching control device 1A shown, to Figure 1 the structure of the phase shift setting unit 3 is added. Other structures are the same as or equivalent to Figure 1 and, for the same or equivalent structural parts, the same reference numerals are attached and repeated descriptions are appropriately omitted. The switching control device 1A according to Embodiment 2 can be applied to Figure 8 the DCDC converter 10 shown in Figure 9 the inverter 20 shown in etc. various power conversion devices.

[0088] In Embodiment 1, it was described that in the frequency setting unit 2, as an example of a plurality of types of carrier frequencies, 4 types of carrier frequencies are set, and a frequency change period T based on the 4 types of carrier frequencies is set. Similarly in Embodiment 2, the case where the frequency setting unit 2 sets 4 types of carrier frequencies is taken as an example for description. Hereinafter, the 4 types of carrier frequencies are respectively set as the first carrier frequency f1, the second carrier frequency f2, the third carrier frequency f'1, and the fourth carrier frequency f'2. That is, the first carrier frequency f1, the second carrier frequency f2, the third carrier frequency f'1, and the fourth carrier frequency f'2 are 4 types of carrier frequencies arbitrarily selected from a plurality of types of carrier frequencies.

[0089] In Embodiment 1, it was explained that the switching rectangular wave generated by the switching control device 1 satisfies the condition that the frequency change period T is longer than the window function width Tw determined by the reciprocal of the resolution bandwidth RBW, and the condition shown in Equation (1A) above. In the switching control device 1A according to Embodiment 2, these two conditions are also satisfied. Under this condition, the phase shift setting unit 3 of the switching control device 1A according to Embodiment 2 sets the phase differences Δφ and Δφ' between the switching rectangular waves determined by the four carrier frequencies.

[0090] Figure 11 This is a diagram showing an example of the time waveform of the switching rectangular wave in Embodiment 2. Figure 11 The time waveform of the switching rectangular wave in the control signal output from the control signal generator 4 according to Embodiment 2 is shown. Figure 11 In the diagram, the horizontal axis represents time, and the vertical axis represents voltage.

[0091] Figure 11 The specific parameter settings are as follows.

[0092] n = 46

[0093] T = 200 μs

[0094] D = 0.5

[0095] f1 = 14.35 kHz (first pulse)

[0096] f2 = 33kHz (second pulse)

[0097] Δφ = 0.913π (between the first and second pulses)

[0098] f'1 = 15kHz (3rd pulse)

[0099] f'2 = 30kHz (4th pulse)

[0100] Δφ' = 0.913π (between the 3rd and 4th pulses)

[0101] In a specific example of Embodiment 2, in the frequency setting unit 2, the first carrier frequency f1, the second carrier frequency f2, the third carrier frequency f'1, and the fourth carrier frequency f'2 are set to f1 = 14.35 kHz, f2 = 33 kHz, f1' = 15 kHz, and f2' = 30 kHz, respectively, and the frequency change period T is set to T = 200 μs. Furthermore, the frequency setting unit 2 sets the duty cycle D = 0.5, which is the ratio of the on-time to the period of the switch. Additionally, n is an integer greater than or equal to 1, representing the order of the higher harmonic components for which noise reduction is desired. Here, n = 46. The phase shift setting unit 3 sets the phase shift amounts Δφ and Δφ' = 0.913π to suppress noise from higher harmonic components around 460 kHz. The meanings of the phase shift amounts Δφ and Δφ' are the same as those of the phase differences Δφ and Δφ'. That is, the frequency setting unit 2 sets the first carrier frequency f1, the second carrier frequency f2, the third carrier frequency f'1, the fourth carrier frequency f'2, the frequency change period T, and the duty cycle D corresponding to the higher harmonic components of the noise to be suppressed, and the phase shift setting unit 3 sets the phase differences Δφ and Δφ corresponding to the higher harmonic components.

[0102] When the frequency change period T set by the frequency setting unit 2 is set to 1 period 2π, the phase difference Δφ is the difference obtained by converting the time between the midpoint between the on and off times of the switch rectangular wave determined by the first carrier frequency f1 and the midpoint between the on and off times of the switch rectangular wave determined by the second carrier frequency f2 into phase. The phase difference Δφ' is the same.

[0103] To reduce switching noise caused by higher harmonic components during the switching operation of the switching element 5, the frequency setting unit 2 sets the first carrier frequency f1 and the second carrier frequency f2, and the phase shift setting unit 3 sets the phase difference Δφ. Similarly, to reduce the switching noise caused by these higher harmonic components, the frequency setting unit 2 sets the third carrier frequency f'1 and the fourth carrier frequency f'2, and the phase shift setting unit 3 sets the phase difference Δφ'. The same applies when there are five or more types of carrier frequencies. Using any one type of carrier frequency as a reference, phase differences Δφ, Δφ', ... are set between it and any other type of carrier frequency, and the phase differences Δφ, Δφ', ... are set between it and all types of carrier frequencies.

[0104] Figure 12 Regarding peak detection, a graph compares the frequency characteristics of electromagnetic noise when using the switched rectangular wave in Embodiment 2, the frequency characteristics of electromagnetic noise when using the switched rectangular wave with a fixed carrier frequency, and the frequency characteristics of electromagnetic noise when using the switched rectangular wave with only a variable carrier frequency. Figure 13This is a graph comparing the frequency characteristics of electromagnetic noise using the switched rectangular wave in Embodiment 2, the switched rectangular wave with a fixed carrier frequency, and the switched rectangular wave with only a variable carrier frequency, regarding average value detection. Figure 12 as well as Figure 13 In the diagram, the horizontal axis represents frequency, and the vertical axis represents noise level (noise voltage).

[0105] like Figure 12 as well as Figure 13 As shown in the upper part, compared with the case of a fixed carrier frequency, when setting four carrier frequencies f1, f2, f'1, and f'2, the noise is reduced to a certain extent in the frequency band from 400kHz to 600kHz, which includes 460kHz, in both peak detection and average detection. Furthermore, as... Figure 12 as well as Figure 13 As shown in the lower part, even when the carrier frequency is variable, if the phase difference Δφ is fixed, although a local reduction in noise is observed in higher harmonic components, the noise of higher harmonic components near 460kHz is not reduced in both peak detection and average detection, and sufficient noise reduction effect cannot be obtained within a certain bandwidth. Generally, the standard upper limit of electromagnetic noise is defined by a certain bandwidth, so the method of setting the four carrier frequencies f1, f2, f'1, and f'2, the frequency change period T, and the phase differences Δφ and Δφ' of the switch control device 1A according to Embodiment 2 is effective in evaluating the standard upper limit.

[0106] Furthermore, the phase difference Δφ, Δφ' = 0.913π in Embodiment 2 is only one example. As shown in Equation (4) described later, there are multiple solutions for the phase difference that can reduce noise at 460kHz. The reduction of noise at 460kHz was previously explained as an example, but the frequency of noise reduction is not limited to 460kHz. For example, the switch control device 1A can also reduce noise in the frequency band where electromagnetic noise reaches its maximum value during circuit resonance.

[0107] Furthermore, in Embodiment 2, the switching rectangular wave is determined by frequency variation and phase shift under the condition that the duty cycle is fixed. However, even if it is interpreted as the switching rectangular wave determined by frequency variation and duty cycle variation under the condition that the phase is fixed, it is possible to specify the same switching rectangular wave as the switching rectangular wave determined by frequency variation and phase shift under the condition that the duty cycle is fixed.

[0108] Next, the specific methods for determining the phase differences Δφ and Δφ' will be explained. Furthermore, the phase difference Δφ between the first carrier frequency f1 and the second carrier frequency f2 will be explained here. Figure 14This is a diagram showing an example of the time waveform of the switching rectangular wave used to illustrate Embodiment 2. Figure 14 This illustrates the concept of a switched rectangular wave. The higher harmonic noise component A of the switched rectangular wave is shown. n As shown in equation (1) below, f(t) can be calculated using the Fourier series expansion of the time waveform f(t) of the switching rectangular wave. f(t) is only valid at time t. 1，on To t 1，off The period and time t are t 2，on To t 2，off During the period t, f(t) becomes a function of f(t) = 1, and outside of that period, it becomes a function of f(t) = 0. At time t 1，on The moment when the rectangular wave is switched on via the first carrier frequency f1 is time t. 1，of f is the time when the rectangular wave is switched off via the first carrier frequency f1, and time t is... 2，on The moment when the rectangular wave is switched on via the second carrier frequency f2 is time t. 2，off It is the moment when the rectangular wave is switched off by the second carrier frequency f2.

[0109] [Formula 1]

[0110]

[0111] From equation (1), it can be seen that the higher harmonic noise component A n It is possible to use the switching time t of the first carrier frequency f1 1，on and t 1，off The two terms determined are exp{-i×(2πnt)} 1，off ) / T} and exp{-i×(2πnt) 1，on ) / T} and the switching time t of the second carrier frequency f2 2，on and t 2，off The two terms determined are exp{-i×(2πnt)} 2，off ) / T} and exp{-i×(2πnt) 2，on The phase difference is represented by ) / T}. Noise can be reduced by choosing a phase difference that minimizes the absolute value of the sum of these two terms. Since the coefficients of each term are equal, the phase relationship on the complex plane of each term can be considered. Figure 15 This shows the switching time t on the complex plane caused by the first carrier frequency f1. 1，on and t 1，off A diagram showing the phase φ1 of the composite vector of the two determined terms. Figure 15 In the middle, time t 1，on As a reference and at time t 1，on =0. The relationship between phase φ1 and each variable is expressed by the following equation (2). For example, the switching control device 1A, in order to satisfy equation (1) and equation (2), sets the switching time t of the first carrier frequency f1 to 0.1，on The reference time, i.e., time t 1，on =0.

[0112] [Equation 2]

[0113]

[0114] Figure 16 This shows the switching time t on the complex plane caused by the second carrier frequency f2. 2，on and t 2，off A diagram of the phase φ2 of the composite vector of the two determined terms. The relationship between the phase φ2 and each variable is expressed by the following equation (3).

[0115] [Formula 3]

[0116]

[0117] Higher harmonic noise component A n The condition for it to decrease is that the switching time t of the first carrier frequency f1... 1，on and t 1，off The resultant vector of the two determined terms and the switching time t of the second carrier frequency f2. 2，on and t 2，off The combined vectors of the two determined terms cancel each other out in the complex plane. That is, as shown in equation (4) below, the phase difference between phase φ1 and phase φ2 can be offset by an odd multiple of π. More generally, as shown in equation (5) below, the phase difference between phase φ1 and phase φ2 can be between π / 2 + 2kπ and 3π / 2 + 2kπ. k is an integer greater than or equal to 1. That is, the switch control device 1A reduces the higher harmonic noise component A n The switching time t of the first carrier frequency f1 on the complex plane 1，on and t 1，off The phase φ1 of the composite vector of the two determined terms and the switching time t in the complex plane determined by the second carrier frequency f2 2，on and t 2，of The phase difference φ2 of the composite vector of the two terms determined by f is to be as close as possible to an odd multiple of π. In Implementation 2, n = 46 is set to reduce noise at 460 kHz in a frequency variation period T = 200 μs. To reduce noise in a certain amplitude frequency band around 460 kHz, a phase difference Δφ = 0.913π is set, but if it is desired to reduce noise at 460 kHz in a narrower frequency band, a phase difference Δφ = π can also be set.

[0118] [Formula 4]

[0119] |φ2-φ1|=(2k-1)π…(4)

[0120] [Formula 5]

[0121]

[0122] As shown in equations (2) and (3), the phases φ1 and φ2 include terms of π / 2, but considering the relative phase difference Δφ = |φ1 - φ2|, (t 1，on +t 1，off ) / 2 and (t 2，on +t 2，off ) / 2 becomes important. That is, we can consider the time difference from the midpoint between the turn-on and turn-off times of a certain switch rectangular wave to the midpoint between the turn-on and turn-off times of the next switch rectangular wave.

[0123] In Embodiment 2, the phase shift is the phase difference Δφ, but the phase shift can also be defined by the time difference Δt. For example, in Embodiment 2, the switching time t of the first carrier frequency f1 is... 1，on The time t is set as the reference. 1，on =0, and then after a time corresponding to the duty cycle D / f1, it switches from the on state to the off state. Then, the on time of the second carrier frequency f2 is set to 1 / f1+Δt. After a time corresponding to the duty cycle D / f2 from the on time of f2, when switching from the on state to the off state, each time can be represented as t. 1，on =0, t 1，off =D / f1,t 2，on =1 / f1+Δt,t 2，off = 1 / f1 + Δt + D / f1. Therefore, according to equations (2), (3) and (4), Δt can be expressed as shown in equation (6) below.

[0124] [Formula 6]

[0125]

[0126] At this point, with n=46, k=61, and D=0.5 in Implementation Method 2, the time difference corresponding to Δφ=0.913π is Δt=14.8μs. Here, t is varied. 2，on The exact time can be varied, but as long as the relative phase difference can be set, t can also be changed. 1，on t 1，off t 2，on and t 2，off At any time. Regarding the timing of the switch, it is also possible that the switching time t of the first carrier frequency f1 is not the same as the switching time t. 1，on To achieve noise reduction, the relative phase difference Δφ can be set as the reference time.

[0127] As described above, in the switch control device 1A according to Embodiment 2, frequency variation and phase shift are used to determine the switch rectangular wave, so noise reduction effect is also obtained in average value detection. In addition, if the switch control device 1A according to Embodiment 2 is used, the same effect can be expected even for devices that use measurement methods other than short-time Fourier transform, such as spectrum analyzers using scanning tuning methods.

[0128] As explained above, the switch control device according to Embodiment 2 includes a phase shift setting unit. This unit sets the phase difference between the various switch rectangular waves determined by the first to fourth carrier frequencies when setting one of a plurality of carrier frequencies as a first carrier frequency, one of a plurality of carrier frequencies different from the first carrier frequency as a second carrier frequency, one different from the first and second carrier frequencies as a third carrier frequency, and one different from the first, second, and third carrier frequencies as a fourth carrier frequency. The phase shift setting unit sets the phase difference in a way that reduces switching noise caused by higher harmonic components due to switching operation. Therefore, the switch control device according to Embodiment 2 can achieve a higher noise reduction effect for various measurement conditions. Furthermore, the switch control device according to Embodiment 2 can change the carrier frequency and phase difference in match with a specific order of higher harmonic components, thus more effectively reducing the noise of that specific order of higher harmonic components.

[0129] Furthermore, the switch control device involved in Embodiment 2 can also be the following switch control device. That is, during the frequency change period, the switch rectangular wave that is turned on at the time t is based on the signal waveform of the control signal that controls the switch operation according to the i-th frequency fi among multiple types of carrier frequencies. i，on and the time t at which the rectangular wave is switched off based on the i-th frequency fi. i，off The calculated phase is set as φ i In this case, the phase shift setting unit can also adjust the phase φ i and phase φ i+1 The phase difference is defined as a value greater than π / m and less than 3π / m. i is an integer greater than or equal to 1, and m represents the number of carrier frequency types. Phase φ i φ can also be used i =πnt i，on / T+πnt i，off / T is defined by the formula. n means the order of higher harmonic components greater than or equal to 1, where the noise reduction is desired. T means the period of frequency variation. Phase φ i and phase φ i+1 The phase difference can also be 2π / m.

[0130] Implementation method 3.

[0131] In Embodiment 2, an example is given where the frequency setting unit 2 of the switch control device 1A having a phase shift setting unit 3 sets four carrier frequencies. In Embodiment 3, an example is given where the frequency setting unit 2 of the switch control device 1A having a phase shift setting unit 3 sets six carrier frequencies. The switch control device 1A according to Embodiment 3 can be applied to... Figure 8 The DC-DC converter 10 shown Figure 9 The inverter 20 shown is one of various power conversion devices.

[0132] The values ​​of each parameter in Implementation Method 3 are as follows.

[0133] n = 33

[0134] T = 200 μs

[0135] f1 = 21kHz

[0136] f2 = 27.8 kHz

[0137] f3 = 61kHz

[0138] φ1=0.75π

[0139] φ2=1.69π

[0140] φ3=0.05π

[0141] Δφ 12 =φ2-φ1=0.94π

[0142] Δφ 23 =φ3-φ2=-1.64π=0.36π

[0143] Δφ 31 =φ1-φ3=0.7π

[0144] f'1 = 20kHz

[0145] f'2 = 30kHz

[0146] f'3 = 60kHz

[0147] φ'1=0.75π

[0148] φ'2=1.69π

[0149] φ'3=0.05π

[0150] Δφ' 12 =φ'2-φ'1=0.94π

[0151] Δφ' 23=φ'3-φ'2=-1.64π=0.36π

[0152] Δφ' 31 =φ'1-φ'3=0.7π

[0153] In the parameters described above, n, T, f1, f2, φ1, and φ2 are the parameters described in Embodiment 2. f3 signifies a carrier frequency different from f1, f2, f'1, and f'2. Furthermore, f'3 signifies a carrier frequency different from f1, f2, f3, f'1, and f'2. φ3 signifies the switching time t of the carrier frequency f3 on the complex plane. 3，on and t 3，off The phase of the composite vector of the two determined terms. Time t 3，on The time t is the moment when the rectangular wave is switched on based on the carrier frequency f3. 3，off This refers to the moment when the rectangular wave is switched off based on the carrier frequency f3. Δφ

[0154] 12 It is the phase difference between φ2 and φ1, Δφ 23 It is the phase difference between φ3 and φ2, Δφ 31 This is the phase difference between φ1 and φ3. The phase difference is defined as a range greater than 0 and less than 2π. φ'1, φ'2, φ'3, Δφ' 12 ,Δφ' 23 and Δφ' 31 It can also be used with φ1, φ2, φ3, Δφ 12 , Δφ

[0155] 23 and Δφ 31 The same explanation applies.

[0156] In implementation method 3, the higher harmonic noise component A of the switching rectangular wave n The relationship between phase φ3 and the variables is expressed by equation (7) below. Δφ ij This is represented by the following equation (9). In equation (9), i and j are one of 1, 2, and 3, respectively, and i and j are different. In Δφ ij In the case that it does not exist in the range above 0 and below 2π, so that Δφ ij The way that exists in the range above 0 and below 2π is to make Δφ ij Replace with Δφ ij +2π or Δφ ij -2π.

[0157] [Formula 7]

[0158]

[0159] [Formula 8]

[0160]

[0161] [Formula 9]

[0162] Δφ ij =φ j -φ i …(9)

[0163] The switch control device according to embodiment 3 controls each Δφ by making each Δφ ij The phase difference Δφ is set in a manner that satisfies the following equation (10). ij It can reduce the noise of the nth higher harmonic components.

[0164] [Formula 10]

[0165]

[0166] Figure 17 This is a diagram illustrating an example of the time waveform of the switching rectangular wave used to explain Embodiment 3. Figure 17 Or it is used to illustrate Δφ 12 , Δφ 23 , Δφ 31 ,Δφ' 12 ,Δφ' 23 and Δφ' 31 The diagram shows the six phase differences. Figure 18 It is shown on the complex plane Figure 17 The six phase differences Δφ shown 12 , Δφ 23 , Δφ 31 ,Δφ' 12 ,Δφ' 23 and Δφ' 31 The image.

[0167] Figure 19 This is a diagram illustrating an example of the time waveform of a switching rectangular wave with a variable frequency.

[0168] Figure 20 This is a diagram illustrating an example of the time waveform of a switching rectangular wave with a fixed frequency. Figure 17 , Figure 19 as well as Figure 20 In the graph, the horizontal axis represents time, and the vertical axis represents voltage. Figure 20 In this context, a fixed switching frequency of 30kHz is used. The fixed switching frequency of 30kHz is chosen to align with the [specific frequency range]. Figure 17 The switching frequency is selected by making the switching loss conditions equal by having the same number of switching operations for the three carrier frequencies.

[0169] Figure 21 Regarding peak detection, a graph compares the frequency characteristics of electromagnetic noise when using the switched rectangular wave in Embodiment 3, the frequency characteristics of electromagnetic noise when using the switched rectangular wave with a fixed carrier frequency, and the frequency characteristics of electromagnetic noise when using the switched rectangular wave with only a variable carrier frequency. Figure 22 This is a graph comparing the frequency characteristics of electromagnetic noise using the switched rectangular wave in Embodiment 3, the switched rectangular wave with a fixed carrier frequency, and the switched rectangular wave with only a variable carrier frequency, regarding average value detection. Figure 21 as well as Figure 22 In the diagram, the horizontal axis represents frequency, and the vertical axis represents noise level (noise voltage).

[0170] like Figure 21 as well as Figure 22 As shown in the upper part, it can be seen that compared with the case of a fixed carrier frequency, in Embodiment 3, the noise is reduced to a certain extent in the frequency band from 310kHz to 400kHz, which includes 330kHz. Furthermore, as... Figure 21 as well as Figure 22 As shown in the upper and lower parts, even when the carrier frequency is variable, if the phase differences Δφ and Δφ' are fixed, the higher harmonic components at 330 kHz are larger than those in Embodiment 3. That is, the method of Embodiment 3 is also effective in reducing the noise of higher harmonic components of a specific order.

[0171] Figure 23 This is a diagram illustrating an example of the hardware structure for implementing the functions of the switch control devices 1 and 1A according to embodiments 1-3. That is, at least a portion of the functions of the frequency setting unit 2, the phase shift setting unit 3, and the control signal generation unit 4 in embodiments 1-3 can be implemented using a processor 97 that executes a program stored in the memory 98.

[0172] Examples of processors 97 are CPUs (Central Processing Units, also known as central processing units, processing units, arithmetic units, microprocessors, microcomputers, processors, DSPs (Digital Signal Processors)) or system LSIs (Large Scale Integration). Examples of memory 98 are RAMs (Random Access Memory) and ROMs (Read Only Memory).

[0173] When at least a portion of the functions of the frequency setting unit 2, phase shift setting unit 3, and control signal generating unit 4 in embodiments 1-3 are implemented using the processor 97, the at least a portion of the functions are implemented using the processor 97 and software, firmware, or a combination of software and firmware. The software or firmware is described as a program and stored in the memory 98. The program stored in the memory 98 may also be referred to as a program that causes a computer to execute at least a portion of the process or method of executing the frequency setting unit 2, phase shift setting unit 3, and control signal generating unit 4 in embodiments 1-3.

[0174] Figure 24 This diagram illustrates another example of the hardware structure used to implement the functions of the switch control devices 1 and 1A according to embodiments 1-3. That is, the functions of the switch control device 1 according to embodiment 1 and the switch control device 1A according to embodiments 2 and 3 can be implemented using a processing circuit 99 as dedicated hardware.

[0175] The processing circuit 99 is, for example, a single circuit, a composite circuit, a programmable processor, a parallel programmable processor, an ASIC (Application Specific Integrated Circuit), an FPGA (Field-Programmable Gate Array), or a combination thereof.

[0176] Furthermore, regarding the functions of the switch control device 1 involved in Embodiment 1 and the switch control device 1A involved in Embodiments 2 and 3, some of these functions can be implemented using dedicated hardware, while others can be implemented using software or firmware. That is, they can also be implemented using... Figure 23 The processor 97 and memory 98 shown implement a portion of the functions of the frequency setting unit 2, phase shift setting unit 3, and control signal generation unit 4 in embodiments 1-3. Figure 24 The processing circuit 99 shown implements the remaining functions.

[0177] The structure shown in the above embodiments is only an example. It can be combined with other known technologies, and a part of the structure can be omitted or changed without departing from the essence.

[0178] (Explanation of reference numerals in the attached diagram)

[0179] 1, 1A: Switching control device; 2: Frequency setting unit; 3: Phase shift setting unit; 4: Control signal generation unit; 5, 15, 24: Switching element; 10: DC-DC converter; 11: Boost chopper circuit; 12, 22: DC power supply; 13, 23: Load; 14: Reactor; 16: Diode; 17: Smoothing capacitor; 20: Inverter; 21: Inverter main circuit; 97: Processor; 98: Memory; 99: Processing circuit.

Claims

1. A switching control device controls the switching operation of a switching element. The switching control device is characterized by comprising: a frequency setting unit that sets multiple types of carrier frequencies and a frequency change period; and a control unit that controls the switching operation of the switching element by changing the multiple types of carrier frequencies at the frequency change period, where the frequency change period is longer than the time width determined by the reciprocal of the resolution bandwidth, when the average number of switching operations in the interval of the frequency change period is set as fave, the average number of switching operations in the interval cut out by the time width is set as fw, the resolution bandwidth is set as RBW, and m is an integer of 2 or more, fw satisfies the relationship of fave - RBW / 2 < fw < fave + RBW / 2.

2. The switching control device according to claim 1, wherein the average number of switching operations is calculated by the harmonic mean of the multiple types of carrier frequencies.

3. The switching control device according to claim 1 or 2, wherein the resolution bandwidth is any value among 200 Hz, 1 kHz, 9 kHz, 10 kHz, 120 kHz, and 1 MHz.

4. The switching control device according to any one of claims 1 to 3, wherein the switching control device comprises a phase shift setting unit. When one carrier frequency among the multiple types of carrier frequencies is set as the first carrier frequency, one carrier frequency different from the first carrier frequency among the multiple types of carrier frequencies is set as the second carrier frequency, one carrier frequency different from the first carrier frequency and the second carrier frequency is set as the third carrier frequency, and one carrier frequency different from the first carrier frequency, the second carrier frequency, and the third carrier frequency is set as the fourth carrier frequency, the phase shift setting unit sets the phase difference between each switching rectangular wave determined by the first carrier frequency to the fourth carrier frequency.

5. The switching control device according to claim 4, wherein the phase shift setting unit sets the phase difference in a manner that reduces the switching noise of the high - order harmonic components generated due to the switching operation.

6. The switching control device according to claim 5, wherein the frequency setting unit sets the multiple types of carrier frequencies, the frequency change period, and the duty ratio corresponding to the high - order harmonic components, and the phase shift setting unit sets the phase difference corresponding to the high - order harmonic components.

7. The switching control device according to any one of claims 4 to 6, wherein During the frequency variation period, it will be based on time t i，on and time t i，off The calculated phase is set as φ i In the case where the time t is... i，on The time t is the moment when the switch rectangular wave is turned on, based on the i-th frequency fi among the multiple types of carrier frequencies, which serves as the control signal waveform for controlling the switch operation. i，off It is the time when the switch rectangular wave is cut off based on the i-th frequency fi. The phase shift setting unit makes the phase φ i and phase φ i+1 The phase difference is defined such that the absolute value of the phase difference is greater than π / m and less than 3π / m. i is an integer of 1 or more, m means the number of types of the carrier frequencies.

8. The switching control device according to claim 7, wherein The phase φ i From φ i =πnt i，on / T+πnt i，off / T is defined as follows n means an integer of 1 or more and the order of the high - order harmonic component for which noise reduction is desired, and T means the frequency change period.

9. The switching control device according to claim 7 or 8, wherein The phase φ i and the phase φ i+1 The phase difference is 2π / m.

10. A power conversion device, characterized in that, it comprises: the switching control device according to any one of claims 1 to 9; and a power conversion circuit including a switching element.

Images