SWITCHING CONTROL UNIT AND POWER CONVERTER UNIT

Abstract

A switching control unit (1) comprises: a frequency setting unit (2) that sets a plurality of carrier frequencies and a frequency change period; and a control signal generation unit (4), which is a control unit that controls a switching operation performed by a switching element by switching the plurality of carrier frequencies in the frequency change period. The frequency change period is set to be longer than a time width (window function width) determined by the reciprocal of a resolution bandwidth. Furthermore, if the average number of switching operations in the sections of the frequency change period is denoted by fave, the average number of switching operations in the sections clipped by the time width is denoted by fw, the resolution bandwidth is denoted by RBW, and m is an integer of 2 or more, then fw is set such that it expresses the relationship: fave − RBW / 2 < fw < fave + RBW / 2

Description

Area

[0001] The present invention relates to a switching control device that controls a switching operation of a switching element and a power converter device. background

[0002] In a power converter device that performs power conversion based on the switching operation of a switching element, electromagnetic noise with a specific frequency and harmonic components of that frequency is generated when switching occurs at a particular frequency. For products equipped with such a power converter device, noise current standards are established based on the product classification, and countermeasures are required if the noise current exceeds an upper limit specified in the standards. A noise filter with an anti-noise component such as an inductor or capacitor can be used as a general countermeasure; however, using a noise filter increases the size of the device and its cost.To solve these problems, a power converter device has traditionally been proposed that includes a frequency-changing device which repeatedly outputs a frequency-changing pattern with a variety of frequency values, and a controller which controls the switching on and off of a switching element at a switching frequency corresponding to the frequency-changing pattern output by the frequency-changing device (see, for example, patent document 1). A power converter device has also been proposed that sets the period of a frequency-changing pattern in order to achieve a noise-suppression effect even under different measurement conditions and acquisition methods (see, for example, patent document 2). Citation list patent document Patent Document 1: Japanese Patent Application Publication JP. 2006-288103 Patent document 2: Japanese patent application disclosure JP 2016-19322 Summary of the invention Problem to be solved by the invention

[0003] Conventional power converter devices reduce electromagnetic noise by using a variety of switching frequencies, but depending on the measurement conditions, sufficient noise reduction may not be achieved. Therefore, there is a need for a technique that can achieve higher noise reduction under different measurement conditions.

[0004] The present invention was made taking into account the foregoing and aims to provide a switching control unit with which higher noise suppression can be achieved under various measurement conditions. Means to solve the problem

[0005] To solve the aforementioned problem and achieve the objective, the switching control device according to the present invention is a switching control device that controls a switching operation performed by the switching element and comprises the following: a frequency setting unit that sets a plurality of carrier frequencies and a frequency change period; and a control unit that controls a switching operation performed by the switching element by switching the plurality of carrier frequencies within the frequency change period. The frequency change period is set to be longer than the time width, which is determined by the reciprocal of the resolution bandwidth.If the average number of switching operations in sections of the frequency change period is denoted by fave, the average number of switching operations in sections clipped with the time width is denoted by fw, the resolution bandwidth is denoted by RBW, and m is an integer of 2 or more, then fw is set to satisfy the following relationship: fave-RBW / 2 <fw<fave+RBW / 2. Effects of the invention

[0006] The switching control unit according to the present invention achieves the effect that higher noise suppression can be achieved under various measurement conditions. Brief description of the drawings Fig. Figure 1 is a diagram illustrating the configuration of a switching control unit according to a first embodiment. Fig. Figure 2 is a diagram illustrating a first example of a time waveform of a switching rectangular wave to explain a frequency change period. Fig. Figure 3 is a diagram illustrating a second example of the time waveform of the switching rectangular wave to explain the frequency change period. Fig. Figure 4 is a diagram illustrating a spectrum calculation method in a short-time Fourier transform and the influence of a window function at the time of calculation. Fig. Figure 5 is a diagram illustrating the control by the switching control unit according to the first embodiment. Fig. Figure 6 is a diagram illustrating the process by which rectangular waves are generated based on in Fig. The 5 carrier frequencies shown are subjected to a short-time Fourier transform. Fig. Figure 7 is a diagram to illustrate the effect in a case where the switching control unit is used according to the first embodiment. Fig. Figure 8 is a diagram showing the configuration of a DC-DC converter, which is a first example of a power converter device using the switching control device according to the first embodiment. Fig. Figure 9 is a diagram showing the configuration of an inverter, which is a second example of the power converter device using the switching control device according to the first embodiment. Fig. Figure 10 is a diagram illustrating the configuration of a switching control unit according to a second embodiment. Fig. Figure 11 is a diagram that shows an example of a time waveform of a switching rectangular wave in the second embodiment. Fig. Figure 12 is a diagram that compares, with respect to peak detection, a frequency characteristic of electromagnetic noise in the case of using the switching square wave in the second embodiment, a frequency characteristic of electromagnetic noise in the case of using a switching square wave whose carrier frequency is fixed, and a frequency characteristic of electromagnetic noise in the case of using a switching square wave whose carrier frequency is variable. Fig. Figure 13 is a diagram comparing, with respect to average detection, a frequency characteristic of electromagnetic noise when using the switching square wave in the second embodiment, a frequency characteristic of electromagnetic noise when using the switching square wave whose carrier frequency is fixed, and a frequency characteristic of electromagnetic noise when using the switching square wave whose carrier frequency is variable. Fig. Figure 14 is a diagram showing an example of a time waveform to illustrate the switching rectangular wave in the second embodiment. Fig. Figure 15 is a diagram illustrating the phase of a composite vector of two terms determined by switching times of a first carrier frequency on a complex plane. Fig. Figure 16 is a diagram illustrating the phase of a composite vector of two terms determined by switching times of a second carrier frequency on the complex plane. Fig. Figure 17 is a diagram illustrating an example of a time waveform to explain a switching rectangular wave in a third embodiment. Fig. 18 is a diagram showing six phase differences from Fig. 17 illustrated in the complex plane. Fig. Figure 19 is a diagram illustrating an example of a time waveform of a switching rectangular wave in a case where the frequency is variable. Fig. Figure 20 is a diagram illustrating an example of a time waveform of a switching rectangular wave in a case where the frequency is fixed. Fig. Figure 21 is a diagram that compares, with respect to peak detection, a frequency characteristic of electromagnetic noise in the case of using the switching square wave in the third embodiment, a frequency characteristic of electromagnetic noise in the case of using a switching square wave whose carrier frequency is fixed, and a frequency characteristic of electromagnetic noise in the case of using a switching square wave whose carrier frequency is variable. Fig. Figure 22 is a diagram comparing, with respect to average detection, a frequency characteristic of electromagnetic noise when using the switching square wave in the third embodiment, a frequency characteristic of electromagnetic noise when using the switching square wave whose carrier frequency is fixed, and a frequency characteristic of electromagnetic noise when using the switching square wave whose carrier frequency is variable. Fig. Figure 23 is a diagram illustrating an example of a hardware configuration for implementing the functions of the switching control units according to the first to third embodiments. Fig. Figure 24 is a diagram illustrating another example of the hardware configuration for implementing the functions of the switching control units according to the first to third embodiments. Description of the embodiments

[0007] In the following, a switching control unit and a power converter unit according to each embodiment are described in detail with reference to the drawings. First embodiment.

[0008] Fig. Figure 1 is a diagram illustrating a configuration of a switching control device 1 according to a first embodiment. The switching control device 1 is a device that controls a switching operation performed by a switching element 5 and includes a frequency setting unit 2 that sets a plurality of carrier frequencies and a frequency change period T, which is the period in which the carrier frequencies change. The switching element 5 is, for example, included in a power conversion circuit, which is included in a power converter device.

[0009] The switching control unit 1 further includes a control signal generation unit 4, which generates a control signal for controlling the switching operation performed by the switching element 5 by converting the multitude of carrier frequencies in the frequency change period T. The control signal generation unit 4 is an example of a control unit. The frequency adjustment unit 2 adjusts the multitude of carrier frequencies such that the switching noise of harmonic components is reduced when the switching element 5 performs the switching operation.

[0010] In a case where the power conversion circuit is an inverter, a frequency ranging from several kHz to approximately 20 kHz is commonly used as the carrier frequency in general-purpose inverters. Alternatively, in a case where the power conversion circuit is a direct current-to-direct current (DC-DC) converter, a carrier frequency from a wide range of values ​​from several kHz to several MHz is commonly used in general-purpose DC-DC converters.

[0011] Fig. Figure 2 is a diagram showing a first example of a time waveform of a switching rectangular wave to illustrate the frequency change period T. Fig. Figure 2 shows two types of carrier frequencies for the purpose of simplifying the description, where the two types of carrier frequencies are f1 and f2, f1=15 kHz and f2=30 kHz, and the duty cycle D is the ratio of the on-time to one period of the switching square wave based on the carrier frequencies f1 and f2, D=0.5. Fig. Figure 3 is a diagram that presents a second example of the time waveform of the switching rectangular wave to illustrate the frequency change period T. Fig. 3 is a diagram for comparison with Fig. 2, and in Fig. 3. A fixed switching frequency f=20 kHz is used. In the Fig. The horizontal axis represents time and the vertical axis represents tension.

[0012] In a case where, for example, the two carrier frequencies f1=15 kHz and f2=30 kHz are set by the frequency setting unit 2, the Fig. The switching square wave shown is output by the control signal generation unit 4. In a case where the carrier frequency is set to a single carrier frequency f=20 kHz by the frequency setting unit 2, for example, the control signal generation unit 4 outputs a switching square wave as shown in Fig. 3 is shown. In the case of the one in Fig. In the second example shown in section 3, the frequency change period T is: T = 1 / f = 0.05 ms. In the first example, shown in Fig. As shown in Figure 2, the control signal is not a square wave in which an on-time is repeated at specific intervals, but rather a square wave in which on-times are repeated, each associated with one of the reciprocals of the two different carrier frequencies. This is particularly true in the case of the first example in Figure 2. Fig. In example 2, the frequency change period T is determined from the sum of the reciprocals of the respective carrier frequencies and is T=1 / f1+1 / f2=0.1 ms.

[0013] In the switching control unit 1 according to the first embodiment, at least two types of carrier frequencies are set. In the first embodiment, the frequency change period T is set to be longer than the time width determined by the reciprocal of a resolution bandwidth (RBW). The at least two types of carrier frequencies can be set taking into account some or all hardware limitations, such as the power of the switching element 5, the loss of a passive component, and a thermal limit, as well as the limitations of a microcomputer, or they can be comprehensively set taking into account the influence of a harmonic on a band of a different order.

[0014] Next, the relationship between different detection methods and a noise reduction effect is described. The detection methods include peak detection, quasi-peak detection, and average detection. Fig. Figure 4 is a diagram illustrating a spectrum calculation method in a short-time Fourier transform and the influence of a window function at the time of calculation.

[0015] In the short-time Fourier transform (FFT), used in electromagnetic noise (EMI) receivers or similar devices, a segment of a time waveform captured at a specific measurement time is windowed out using a window function and subjected to a fast Fourier transform (FFT) to capture a spectrum within that segment. The segments to be windowed out are shifted sequentially to capture a multitude of spectra. A peak value from each set of spectra is extracted, resulting in a peak-detection spectrum, and an average of these is calculated, resulting in an average-detection spectrum.Quasi-peak detection is a method in which a spectrum is obtained by adding a time-constant circuit to the peak detection process, and is essentially a method in which a peak value is extracted. In the first embodiment of the method described below, the switching repetition period with respect to a time constant is sufficiently fast such that a spectrum is obtained that is substantially similar to the spectrum obtained by peak detection. Hereafter, in this description, peak detection and quasi-peak detection will be referred to collectively as "peak detection" where appropriate.

[0016] A window function width Tw, which is a time width of the window function, is determined by the reciprocal of the resolution bandwidth RBW and takes on different values ​​depending on the standard or band of interest. Representative values ​​of the resolution bandwidth RBW include 200 Hz, 1 kHz, 9 kHz, 10 kHz, 120 kHz, and 1 MHz. For example, in a band of 150 kHz or less, RBW can be defined as RBW = 200 Hz, and in a band of 150 kHz to 30 MHz, RBW can be defined as RBW = 9 kHz (or 10 kHz).

[0017] Fig. Figure 4 shows spectrum 1, spectrum 2, and spectrum 3 as examples of spectra acquired by stepwise shifting sections cut out by the window function. Among these three spectra, 1 to 3, the frequency bands with large spectral values ​​differ. Therefore, the spectra differ, as in the lower range of Fig. Figure 4 illustrates a significant difference between the case where detection is performed by average detection and the case where detection is performed by peak detection, and achieving the noise reduction effect with peak detection is difficult. Furthermore, when evaluating the noise reduction effect through peak detection, it is necessary to strictly maintain a relationship between the position of the window function and the peak position of the spectrum, making the evaluation of the noise reduction effect challenging. Therefore, the following method is proposed in the first embodiment.

[0018] Fig. Figure 5 is a diagram illustrating the switching control by the switching control unit 1 according to the first embodiment. More precisely, it shows Fig. 5 temporal changes in the carrier frequencies. In Fig. In 5, the number of carrier frequency types is four, where the four carrier frequency types are f1, f2, f3 and f4, f1=49 kHz, f2=39 kHz, f3=50 kHz and f4=38 kHz, and the frequency change period TT=5 ms. Fig. In 5, the horizontal axis represents time, and the vertical axis represents the value of the carrier frequency.

[0019] As in Fig. As shown in Figure 5, a pattern containing f1, f1, f2, and f2 is repeated in a first 2.5 ms interval, and a pattern containing f3, f3, f4, and f4 is repeated in a subsequent 2.5 ms interval. Then, the pattern containing f1, f1, f2, and f2 returns in the next 2.5 ms interval, and the pattern containing f3, f3, f4, and f4 returns in yet another 2.5 ms interval. Accordingly, the frequency change period T is 5 ms.

[0020] Fig. Figure 6 is a diagram illustrating a process in which rectangular waves are projected onto the Fig. The five carrier frequencies shown are subjected to a short-time Fourier transform. If RBW = 9 kHz, the window function width Tw = 0.111 ms. Although the calculation is omitted, the repetition period of the pattern containing f1, f1, f2, and f2 is 0.0921 ms, and the repetition period of the pattern containing f3, f3, f4, and f4 is 0.0926 ms. Accordingly, as shown in Fig. Figure 6 shows four switching square waves within a window function width Tw. Since the frequency change period T = 5 ms, there is a relationship between the frequency change period T and the window function width Tw: T > Tw. That is, in the first embodiment, 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.

[0021] Here, in the case of the in Fig. The following 14 patterns are obtained from the 5 shown switching rectangular waves using the four types of carrier frequencies f1, f2, f3 and f4 as patterns of combinations of sections to be cut out with the window function width Tw. <Muster nach Trägerfrequenzen f1 und f2> (a1) f1, f1, f2 and f2 (a2) f1, f2, f2 and f1 (a3) f2, f2, f1 and f1 (a4) f2, f1, f1 and f2 <Muster nach Trägerfrequenzen f3 und f4> (a5) f3, f3, f4 and f4 (a6) f3, f4, f4 and f3 (a7) f4, f4, f3 and f3 (a8) f4, f3, f3 and f4 <Andere Muster> (a9) f1, f2, f2 and f3 (a10) f2, f2, f3 and f3 (a11) f2, f3, f3 and f4 (a12) f3, f4, f4 and f1 (a13) f4, f4, f1 and f1 (a14) f4, f1, f1 and f2

[0022] (a1) to (a4) are patterns that occur in a repeating section of f1 and f2, corresponding to the first 2.5 ms section in Fig. 5 corresponds to. Fig. Figure 6 shows spectrum 1 when the pattern of (a1) is subjected to an FFT with a window function wf1, spectrum 2 when the pattern of (a4) is subjected to an FFT with a window function wf2, spectrum 3 when the pattern of (a2) is subjected to an FFT with a window function wf3, and spectrum 4 when the pattern of (a3) ​​is subjected to an FFT with a window function wf4. In these sections, both f1 and f2 appear twice in the patterns, and the same spectrum can be obtained even if the window function width Tw is shifted as shown in the figure.

[0023] Furthermore, (a5) to (a8) are patterns that occur in a repeating section of f3 and f4, which corresponds to the first 2.5 ms section in Fig. The following 2.5 ms section is shown in (a5) to (a8), and in these sections both f3 and f4 occur twice. Accordingly, the same spectrum is obtained in (a5) to (a8) even if the window function width Tw is shifted. Furthermore, (a9) to (a11) are patterns that occur at the moment of transition from the repeating section of f1 and f2 to the repeating section of f3 and f4, and (a12) to (a14) are patterns that occur at the moment of transition from the repeating section of f3 and f4 to the repeating section of f1 and f2. The spectra in these sections differ slightly from those in (a1) to (a4) or (a5) to (a8), but as can be seen from Fig. As can be seen in Figure 5, these are patterns that occur temporarily in sections where the frequency change period T = 5 ms, and the ratio of the number of occurrences in the frequency change period T is also small, so there is no significant influence on a spectrum calculation process. It should be noted that in the case where the difference between the values ​​of f1 and f3 and the difference between the values ​​of f2 and f4 is as in the example in Fig. Since 5 in this description are set small, the influence of the difference in the spectra themselves at the time of switching between the sets of carrier frequencies is extremely small.

[0024] The in Fig. 5 and Fig. The patterns shown in Figure 6 are examples of switching square wave patterns in the first embodiment. When the condition for the switching square wave patterns in the first embodiment is generalized, the condition can be expressed by the following formula (1A). fave−RBW / 2 <fw<fave+RBW / 2

[0025] In the formula (1A) above, fave is the average number of switching operations in sections of the frequency change period T, and fw is the average number of switching operations in sections cut out with the window function width Tw. In the case where a plurality of carrier frequencies are used, as in the first embodiment, the average number of switching operations can be calculated by the harmonic mean of the plurality of carrier frequencies. It should be noted that the harmonic mean here also includes the concept of a weighted harmonic mean.

[0026] The above formula (1A) can also be called |fw-fave| <RBW / 2 ausgedrückt werden. Diese Formel bedeutet, dass der Absolutwert der Differenz zwischen der durchschnittlichen Anzahl von Schaltvorgängen fave in den Abschnitten der Frequenzänderungsperiode T und der durchschnittlichen Anzahl von Schaltvorgängen fw in den mit der Fensterfunktionsbreite Tw ausgeschnittenen Abschnitten kleiner als 1 / 2 der Auflösungsbandbreite RBW ist. Dies ist zufriedenstellend, solange diese Bedingung und die oben beschriebene Bedingung, dass die Frequenzänderungsperiode T länger ist als die Fensterfunktionsbreite Tw, die eine durch den Kehrwert der Auflösungsbandbreite RBW bestimmte Zeitbreite ist, erfüllt sind. Wenn die Schalt-Rechteckwelle in einem vom Schaltsteuergerät 1 erzeugten Steuersignal diese beiden Bedingungen erfüllt, kann der Einfluss der Fensterfunktionsbreite Tw auf ein durch die Durchschnittserfassung erhaltenes Spektrum und ein durch die Spitzenerfassung erhaltenes Spektrum verringert werden.

[0027] Fig. Figure 7 is a diagram illustrating the effect in the case where the switching control unit 1 is used according to the first embodiment. Fig. 7 means “conventional method 1 (frequency is fixed)”, in which a switching square wave with a fixed carrier frequency is used. Hereafter, conventional method 1 (frequency is fixed) will simply be referred to as “conventional method 1”. The “proposed method (first embodiment)” is a method of the first embodiment in which the two carrier frequencies in the two in Fig. The five 2.5 ms segments shown are switched. Hereafter, the proposed method (first embodiment) is simply referred to as the "proposed method." Furthermore, "conventional method 2 (frequency is variable)" means that a pattern is used in which f1 and f2 are repeated alternately as f1, f2, f1, f2... This method is considered an example of a general frequency-variable method. Hereafter, conventional method 2 (frequency is variable) is simply referred to as "conventional method 2."

[0028] In the upper left area of Fig. Figure 7 shows the frequency characteristic of the noise current through average acquisition in the case of using the proposed method, represented by a thick solid line, and the frequency characteristic of the noise current through average acquisition in the case of using the conventional method 1, represented by a thin solid line. In the upper right area of Fig. Figure 7 shows the frequency characteristic of the noise current through peak detection in the case of using the proposed method by a thick solid line, and the frequency characteristic of the noise current through peak detection in the case of using the conventional method 1 is shown by a thin solid line.

[0029] In the lower left area of Fig. Figure 7 shows the frequency characteristic of the noise current through average acquisition in the case of conventional method 2, represented by a thick solid line. For comparison, the characteristic curve shown in the upper left area according to conventional method 1 is represented by a thin solid line. In the lower right area of Fig. Figure 7 shows the frequency characteristic of the noise current obtained by peak value acquisition using conventional method 2, represented by a thick solid line. For comparison, the characteristic curve according to conventional method 1, shown in the upper right area, is represented by a thin solid line. Fig. 7. Each horizontal axis represents the frequency, and each vertical axis represents the level of the noise current.

[0030] The proposed method makes it possible to achieve a higher noise reduction effect under different measurement conditions, as described in the section "Problems to be solved by the invention." As a specific example of "different measurement conditions," the following cases are considered here: (1) the case in which the evaluation is performed by both peak detection and average detection, and (2) the case in which the evaluation is performed under different RBW conditions. Generally, the resolution bandwidth (RBW) is defined for each frequency band to be measured. For example, in a band of 150 kHz or less, the RBW may be defined as RBW = 200 Hz, and in a band of 150 kHz to 30 MHz, the RBW may be defined as RBW = 9 kHz (or 10 kHz), as described above. Each diagram in Fig. 7 is also measured using these RBW values. Considering Fig. 7. From this perspective, it is evident that when comparing the proposed method with the conventional method 2, the noise reduction effects remain at a similar level for peak detection, while a higher noise reduction effect is achieved for average detection with the proposed method (see the range around 1 MHz). Therefore, from the perspective of (1), a stronger noise reduction effect is achieved with the proposed method. Furthermore, when comparing from the perspective of (2), in the band from 150 kHz to 30 MHz, where RBW = 9 kHz, the noise reduction effects achieved with the proposed method and the conventional method 2 are equivalent. On the other hand, in the band of 150 kHz or less, where RBW = 200 Hz, a higher noise reduction effect is achieved with the proposed method (see the range around 90 kHz).In this respect, both cases show a similar tendency for average detection as well as peak detection. It follows from the above that the proposed method can achieve a higher noise reduction effect under different measurement conditions, both from the perspective of (1) and from the perspective of (2). It should be noted that the example in . Fig. 7 was described using the noise current, but the procedure in this description is not limited to the noise current standards.

[0031] Fig. Figure 8 is a diagram showing a configuration of a DC-DC converter 10, which is a first example of a power converter device using the switching control device 1 according to the first embodiment. The DC-DC converter 10 includes the switching control device 1 described above and a boost chopper circuit 11, which is 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 an inductor 14, a switching element 15, a diode 16, and a smoothing capacitor 17.

[0032] The switching element 15 performs a switching operation at a time corresponding to a control signal output by the control signal generation unit 4, which is included in the switching control device 1. The boost chopper circuit 11 increases the voltage of the input power from the DC power supply 12 and delivers an output power at a desired voltage to the load 13. A semiconductor switching element, such as a metal-oxide-semiconductor field-effect transistor (MOSFET) or an insulated-gate bipolar transistor (IGBT), is used as the switching element 15, with the diode 16 connected in antiparallel to it.

[0033] The DC-DC converter 10 changes the duty cycle of the switching square wave depending on the state of the load 13 in order to obtain the desired DC voltage.

[0034] The power conversion circuit can be a different device than the boost chopper circuit 11, for example a buck chopper circuit.

[0035] Fig. Figure 9 is a diagram showing a configuration of an inverter 20, which is a second example of the power converter device using the switching control unit 1 according to the first embodiment. The inverter 20 includes the switching control unit 1 according to the first embodiment and the inverter main circuit 21, which is 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 includes switching elements 24.

[0036] Each switching element 24 performs a switching operation at a time corresponding to the control signal output by the control signal generation unit 4, which is included in the switching control device 1. The inverter main circuit 21 increases the voltage of the input power from the DC power supply 22 and delivers the desired AC output power to the load 23. A semiconductor switching element such as a MOSFET or an IGBT, in which a diode is connected in antiparallel, is used as the switching element 24.

[0037] The inverter main circuit 21 changes the duty cycle of the switching square wave according to a pulse width modulation control in order to apply a desired AC voltage of the inverter to the load 13.

[0038] As described above, the switching control unit according to the first embodiment is the switching control unit that controls the switching operation performed by the switching element and includes the frequency setting unit and the control unit. The frequency setting unit sets the plurality of carrier frequencies and the frequency change period, and the control unit controls the switching operation performed by the switching element by switching the plurality of carrier frequencies within the frequency change period. The frequency change period is set to be longer than a time width determined by the reciprocal of the resolution bandwidth.Furthermore, if the average number of switching operations in the frequency-change period sections is denoted by fave, the average number of switching operations in the time-width-snipped sections is denoted by fw, the resolution bandwidth is denoted by RBW, and m is an integer of 2 or more, then fw is set to give the relationship: fave-RBW / 2 <fw<fave+RBW / 2 erfüllt. Durch die Verwendung des wie oben beschrieben eingestellten Schalt-Rechtecksignals kann der Einfluss der Fensterfunktionsbreite auf das durch die Durchschnittserfassung erhaltene Spektrum und das durch die Spitzenerfassung erhaltene Spektrum verringert werden. Dementsprechend ermöglicht die Verwendung des Schaltsteuergeräts gemäß der ersten Ausführungsform, unter verschiedenen Messbedingungen einen höheren Rauschunterdrückungseffekt zu erzielen. Second embodiment.

[0039] Fig. Figure 10 is a diagram illustrating a configuration of a switching control unit 1A according to a second embodiment. Comparing the two, the following is shown: Fig. 10 with Fig. 1, so you get the in Fig. 10 shown switching control unit 1A, by changing the configuration in Fig. 1. A phase shift adjustment unit 3 is added. The rest of the configuration is identical or equivalent to that in Fig. 1. Identical or equivalent components are identified with the same reference numerals, and redundant descriptions thereof are omitted accordingly. The switching control unit 1A according to the second embodiment can be applied to various power converter devices, such as the one described in Fig. 8 shown DC-DC converter 10 and the one in Fig. 9 inverters shown 20.

[0040] In the first embodiment, it was described that the frequency setting unit 2 sets four types of carrier frequencies as an example of the multitude of carrier frequency types and sets the frequency change period T based on these four carrier frequency types. In the second embodiment, a similar case is described in which the frequency setting unit 2 sets four types of carrier frequencies. Hereinafter, the four types of carrier frequencies are referred to 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 four types of carrier frequencies that are freely selected from the multitude of carrier frequency types.

[0041] In the first embodiment, it was described that the switching square wave generated by the switching control unit 1 fulfills 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 specified by the formula (1A) above. The switching control unit 1A according to the second embodiment is also based on fulfilling these two conditions. Under this condition, the phase shift adjustment unit 3, which is included in the switching control unit 1A according to the second embodiment, sets phase differences Δφ and Δφ' between switching square waves, which are determined by the four types of carrier frequencies.

[0042] Fig. Figure 11 is a diagram illustrating an example of a time waveform of a switching rectangular wave in the second embodiment. Fig. Figure 11 illustrates a time waveform of a switching square wave in a control signal output by the control signal generation unit 4 according to the second embodiment. Fig. In figure 11, the horizontal axis represents time and the vertical axis represents tension.

[0043] Concrete examples of in Fig. The 11 configured parameters are as follows. n=46 T=200 μs D=0.5 f1=14.35 kHz (first impulse) f2=33 kHz (second impulse) Δφ=0.913π (between the first impulse and the second impulse) f'1=15 kHz (third impulse) f'2=30 kHz (fourth impulse) Δφ'=0.913π (between the third impulse and the fourth impulse)

[0044] In the specific examples of the second embodiment, the frequency setting unit 2 sets f1 = 14.35 kHz, f2 = 33 kHz, f1' = 15 kHz, and f2' = 30 kHz as the first carrier frequency f1, second carrier frequency f2, third carrier frequency f'1, and fourth carrier frequency f'2, respectively, and sets T = 200 µs as the frequency change period T. Furthermore, the frequency setting unit 2 sets the duty cycle D = 0.5, where the duty cycle is the ratio of the on-time to one switching period. n is an integer of 1 or more, indicating the order of a harmonic component for which noise reduction is desired. Here, n = 46 is set. The phase shift setting unit 3 sets the phase shift values ​​Δφ and Δφ' = 0.913π such that the noise of a harmonic component is reduced by 460 kHz. The phase shift values ​​Δφ and Δφ' have the same meaning as 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 f1, the fourth carrier frequency f2, the frequency change period T and the duty cycle D as a function of a harmonic component for which noise suppression is desired, and the phase shift setting unit 3 sets the phase differences Δφ and Δφ as a function of the harmonic component.

[0045] If one period of the frequency change period T set by the frequency setting unit 2 is 2π, the phase difference Δφ is a difference obtained by converting a difference between the intermediate time between an on-time and an off-time of the switching square wave determined by the first carrier frequency f1 and an intermediate time between an on-time and an off-time of the switching square wave determined by the second carrier frequency f2 into a phase. The same applies to the phase difference Δφ'.

[0046] Frequency setting unit 2 sets the first carrier frequency f1 and the second carrier frequency f2, and phase shift setting unit 3 sets the phase difference Δφ so that the switching noise of the harmonic components is reduced when the switching element 5 performs the switching operation. Similarly, frequency setting unit 2 sets the third carrier frequency f'1 and the fourth carrier frequency f'2, and phase shift setting unit 3 sets the phase difference Δφ' so that the switching noise of the harmonic components is reduced. The same applies if there are five or more types of carrier frequencies. Using any type of carrier frequency as a reference, the phase differences Δφ, Δφ', ... are set with respect to any other type of carrier frequency, and a phase difference setting operation Δφ, Δφ', ... is performed with respect to all types of carrier frequencies.

[0047] Fig. Figure 12 is a diagram that compares, with respect to peak detection, a frequency characteristic of electromagnetic noise in the case of the use of a switching square wave in the second embodiment, a frequency characteristic of electromagnetic noise in the case of the use of a switching square wave whose carrier frequency is fixed, and a frequency characteristic of electromagnetic noise in the case of the use of a switching square wave whose carrier frequency is variable. Fig. Figure 13 is a diagram comparing, with respect to average detection, a frequency characteristic of electromagnetic noise in the case of using the switching square wave in the second embodiment, a frequency characteristic of electromagnetic noise in the case of using the switching square wave whose carrier frequency is fixed, and a frequency characteristic of electromagnetic noise in the case of using the switching square wave whose carrier frequency is variable. Fig. 12 and Fig. 13 Each horizontal axis represents the frequency, and each vertical axis represents the noise level (noise voltage).

[0048] It is evident that, as in the upper sections in Fig. 12 and Fig. Figure 13 shows that the noise in a specific area within a band from 400 kHz to 600 kHz, including 460 kHz, is reduced when the four types of carrier frequencies f1, f2, f'1, and f'2 are set for both peak and average detection, compared to when the carrier frequency is fixed. Furthermore, as shown in the lower ranges of the Fig. 12 and Fig. Figure 13 shows that, in a case where the phase difference Δφ is fixed even when the carrier frequency is variable, a harmonic component is also observed in which the noise is locally reduced. However, the noise of a harmonic component around 460 kHz is not reduced in either peak or average detection, and no sufficient noise reduction effect is achieved with a given bandwidth. Since the limit value in electromagnetic noise standards is generally defined within a specific bandwidth, a method in which the switching control device 1A, according to the second embodiment, sets the four types of carrier frequencies f1, f2, f'1, and f'2, the frequency change period T, and the phase differences Δφ and Δφ' is effective in evaluating such a limit value in the standards.

[0049] The phase differences Δφ and Δφ' = 0.913π in the second embodiment are merely an example, and there are a multitude of phase difference solutions that can reduce noise at 460 kHz according to formula (4) described later. Although noise reduction at 460 kHz has been described as an example so far, the frequency at which noise is reduced is not limited to 460 kHz. For example, the switching control unit 1A can reduce noise in a band where electromagnetic noise has a maximum value at a circuit resonance.

[0050] In the second embodiment, the switching square wave is determined using the variable frequency and phase shift, provided that the duty cycle is fixed. However, even assuming that the variable frequency and a variable duty cycle are used, provided that the phase is fixed, it is possible to define a switching square wave similar to the switching square wave determined using the variable frequency and phase shift, provided that the duty cycle is fixed.

[0051] Next, a specific procedure for determining the phase differences Δφ and Δφ' is described. Here, the phase difference Δφ between the first carrier frequency f1 and the second carrier frequency f2 is described. Fig. Figure 14 is a diagram showing an example of a time waveform to illustrate a switching rectangular wave in the second embodiment. Fig. Figure 14 illustrates the concept of a switching square wave. A harmonic noise component A n The switching square wave can be calculated by Fourier series expansion of a time waveform f(t) of the switching square wave, as expressed by the following formula (1). f(t) is a function such that f(t) = 1 only if the time t between t 1,on and t 1,off lies and if the time t between t 2,on and t 2,off The time t lies, and f(t)=0 otherwise holds. 1,on is the time at which the switching square wave is switched on by the first carrier frequency f1, the time t 1,off is a time at which the switching square wave is switched off by the first carrier frequency f1, the time t 2,on is a time at which the switching square wave is switched on by the second carrier frequency f2, and the time t 2,offis a time at which the switching square wave is switched off by the second carrier frequency f2. Formula 1: An=1T∫−T / 2T / 2f(t)e−i2πntTdt=i2πn(e−i2πnt1,offT−e−i2πnt1,onT+e−i2πnt2,offT−e−i2πnt2,onT) f(t)={1(t1,on≤t≤t1,off, t2,on≤t≤t2,off)0 (otherwise)

[0052] From formula (1) it can be seen that the harmonic noise component A n by using two terms exp{-i×(2πnt 1,off ) / T} and exp{-i×(2πnt 1,on ) / T} can be expressed by the switching times t 1,on and t 1,off the first carrier frequency f1 is determined, and two terms exp{-i×(2πnt 2,off ) / T} and exp{-i×(2πnt 2,on ) / T} can be expressed by the switching times t 2,on and t 2,offThe second carrier frequency f2 can be determined. The noise can be reduced by choosing the phase difference such that the absolute value of the sum of the two terms is decreased. Since the coefficients of the respective terms are equal, it suffices to consider a phase relationship between the respective terms on the complex plane. Fig. Figure 15 is a diagram representing a phase φ1 of a composite vector of two terms, defined by the switching times t 1,on and t 1,off the first carrier frequency f1 is determined on the complex plane. Fig. 15 is the time t 1,on a reference, and it applies t 1,on =0. The relationship between the phase φ1 and each variable is expressed by the following formula (2). For example, the switching control unit 1A sets the switching time t 1,on The first carrier frequency f1 is fixed as the reference time, i.e., time t. 1,on =0, for formulas (1) and (2). Formula 2: ϕ1=−πnt1,onT+π2−πnt1,offT

[0053] Fig. Figure 16 is a diagram representing a phase φ2 of a composite vector of two terms, defined by the switching times t 2,on and t 2,off The second carrier frequency f2 is determined on the complex plane. A relationship between the phase φ2 and each variable is expressed by the following formula (3).

[0054] Formula 3: ϕ2=−πnt2,onT+π2−πnt2,offT

[0055] A condition under which the harmonic noise component A n The decrease is due to the fact that the composite vector of two terms, which is divided by the switching times t, decreases. 1,on and t 1,off the first carrier frequency f1 is determined, and the composite vector of two terms, which is determined by the switching times t 2,on and t 2,offThe second carrier frequency f2 cancels each other out on the complex plane. That is, it suffices if the phase difference between phase φ1 and phase φ2 is shifted by an odd multiple of π, as expressed by the following formula (4). In a broader sense, it suffices if the phase difference between phase φ1 and phase φ2 lies between π / 2 + 2kπ and 3π / 2 + 2kπ, as expressed by the following formula (5). k is an integer of 1 or more. That is, to reduce the harmonic noise component A n To reduce the phase difference, the switching control unit 1A approximates the phase difference between the phase φ1 of the composite vector of the two terms, which is determined by the switching times t. 1,on and t 1,off the first carrier frequency f1 on the complex plane, and the phase φ2 of the composite vector of the two terms, which is determined by the switching times t 2,onand t2, off the second carrier frequency f2 in the complex plane, to a value as close as possible to an odd multiple of π. In the second embodiment, n=46 is set to reduce the noise at 460 kHz in the frequency-shift period T=200 µs. Although the phase difference Δφ=0.913π is set to reduce the noise in a band with a certain range around 460 kHz, the phase difference Δφ=π can be set in a case where it is desirable to reduce the noise at 460 kHz in a narrower band. Formula 4: |ϕ2−ϕ1|=(2k−1)π Formula 5: π2+2kπ<|ϕ2−ϕ1|<3π2+2kπ

[0056] As expressed by formulas (2) and (3), phase φ1 and phase φ2 contain a term of π / 2, but in a case where a relative phase difference of the phase difference Δφ=|φ1-φ2| is considered, (t 1,on +t 1,off ) / 2 and (t 2,on +t2,off ) / 2 is important. That is, it is sufficient to consider a time difference between an intermediate time between an on-time and an off-time of a specific switching square wave and an intermediate time between an on-time and an off-time of the next switching square wave.

[0057] In the second embodiment, the phase shift magnitude is the phase difference Δφ, but the phase shift magnitude can be defined by a time difference Δt. For example, let us assume that in the second embodiment the switching time t 1,on the first carrier frequency f1 is set as the reference time, i.e. t 1,onIf f = 0, then an on state is switched to an off state after a time D / f1 corresponding to the duty cycle, then the on time of the second carrier frequency f2 is set to 1 / f1+Δt, and the on state is switched to the off state after a time D / f2 corresponding to the duty cycle, starting from the on time of f2, where the respective times are denoted as t 1,on =0, t 1,off =D / f1, t 2,on =1 / f1+Δt and t 2,off =1 / f1+Δt+D / f1. Therefore, Δt can be expressed from formulas (2), (3) and (4) by the following formula (6). Formula 6: Δt=2k−12nT−2−Df1−Df2

[0058] At this point in time, when n=46, k=61 and D=0.5 in the second embodiment, the time difference corresponding to Δφ=0.913π is Δt=14.8 µs. Here, the time t 2,on postponed, but each of the times t 1,on , t 1,off , t 2,on and t 2,offThe switching time can be shifted as long as a relative phase difference can be set. With regard to the switching time, the switching time t must be considered. 1,on The first carrier frequency f1 does not need to be set as the reference time, and it is sufficient that the relative phase difference Δφ can be adjusted to achieve the noise reduction effect.

[0059] As described above, in the switching control unit 1A according to the second embodiment, the switching square wave is determined using the variable frequency and phase shift, thereby achieving the noise reduction effect even during average acquisition. Furthermore, by using the switching control unit 1A according to the second embodiment, a similar effect can be expected to be achieved in a device that uses a measurement method other than the short-time Fourier transform, such as a sweep-tuned spectrum analyzer.

[0060] As described above, the switching control unit according to the second embodiment includes the phase shift adjustment unit, which, when one of the multitude of carrier frequencies is the first carrier frequency, one of the multitude of carrier frequencies different from the first carrier frequency is the second carrier frequency, one different from the first and second carrier frequencies is the third carrier frequency, and one different from the first, second, and third carrier frequencies is the fourth carrier frequency, adjusts the phase difference between the respective switching square waves determined by the first through fourth carrier frequencies. The phase shift adjustment unit adjusts the phase difference in such a way as to reduce the switching noise of the harmonic components generated by the switching process.Consequently, the switching control unit according to the second embodiment can achieve a higher noise reduction effect under various measurement conditions. Since the switching control unit according to the second embodiment can also change the carrier frequency and the phase difference according to a harmonic of a specific order, it is possible to reduce the noise of the harmonic of that specific order more effectively.

[0061] It should be noted that, according to the second embodiment, the switching control unit can be the following switching control unit. That is, in a case where one phase is connected with φ i is designated as the phase based on time t i,on is calculated when a switching square wave, which is a signal waveform of a control signal for controlling the switching process, is switched on by an i-th frequency fi among the plurality of carrier frequencies, and the time t i,off, when the switching square wave is switched off by the i-th frequency fi in the frequency change period, the phase shift adjustment unit can adjust the phase difference so that the absolute value of a phase difference between a phase φ i and a phase φ i +1 π / m or more and 3 π / m or less. i is an integer of 1 or more, and m denotes the number of carrier frequency types. The phase φ i can be expressed using the formula φi=πnt i,on / T+πnt i,off / T are defined. n is an integer of 1 or more and represents the order of a harmonic component for which noise reduction is desired, and T represents a frequency change period. The phase difference between the phase φ i and the phase φ i +1 can be 2π / m. Third embodiment.

[0062] In the second embodiment, an example is given of a case in which the frequency setting unit 2 sets four types of carrier frequencies in the switching control unit 1A, including the phase shift setting unit 3. In a third embodiment, an example is given of a case in which the frequency setting unit 2 sets six types of carrier frequencies in the switching control unit 1A, including the phase shift setting unit 3. The switching control unit 1A according to the third embodiment can be applied to various power converter devices, such as the one described in Fig. 8 DC-DC converters shown 10 and the one in Fig. 9 inverters shown 20.

[0063] The parameter values ​​in the third embodiment are as follows. n=33 T=200 μs f1=21 kHz f2=27.8 kHz f3=61 kHz φ1=0.75π φ2=1.69π φ3=0.05π Δφ12=φ2−φ1=0.94π Δφ23=φ3−φ2=−1.64π=0.36π Δφ31=φ1−φ3=0.7π f'1=20 kHz f'2=30 kHz f"3=60 kHz φ'1=0.75π φ'2=1.69π φ'3=0.05π Δφ'12=φ'2−φ'1=0.94π Δφ'23=φ'3−φ'2=−1.64π=0.36π Δφ'31=φ'1−φ'3=0.7π

[0064] In the parameters above, n, T, f1, f2, φ1, and φ2 are those described in the second embodiment. f3 denotes a carrier frequency that differs from f1, f2, f'1, and f'2. φ3 denotes a phase of a composite vector of two terms, determined by the switching times t 3,on and t 3,off The carrier frequency f3 is determined on the complex plane. The time t 3,onis a time at which a switching square wave is switched on by the carrier frequency f3, and the time t 3,off Δφ is the point in time at which the switching square wave is switched off by the carrier frequency f3. 12 is a phase difference between φ2 and φ1, Δ φ 23 is a phase difference between φ3 and φ2 and Δφ 31 is a phase difference between φ1 and φ3. The phase difference is defined in a range from 0 to 2π inclusive. Descriptions of φ'1, φ'2, φ'3, Δφ' 12 , Δφ' 23 and Δφ' 31 can be analogous to those of φ1, φ2, φ3, Δφ 12 , Δφ 23 and Δφ 31 be given.

[0065] In the third embodiment, the harmonic noise component A n The switching square wave is expressed by the following formula (7). The relationship between the phase φ3 and each variable is expressed by the following formula (8). Δφ ijis expressed by the following formula (9). In formula (9), each of i and j is an arbitrary number from 1, 2, and 3, and i is not equal to j. In a case where Δφ ij If it does not exist in the range from 0 to 2π inclusive, then Δφ ij by Δφ ij +2π or Δφ ij -2π is replaced so that Δφ ij exists in the range from 0 to 2π inclusive. Formula 7: An=1T∫−T / 2T / 2f(t)e−i2πntTdt =i2πn(e−i2πnt1,offT−e−i2πnt1,onT+e−i2πnt2,offT−e−i2πnt2,onT+e−i2πnt3,offT−e−i2πnt3,onT)f(t)={1(t1,on≤t1,off, t2,on≤t≤t2,off, t3,on≤t≤t3,off) 0 (otherwise) Formula 8: ϕ3=−πnt3,onT+π2−πnt3,offT Formula 9: Δϕij=ϕj−ϕi

[0066] The switching control unit according to the third embodiment can reduce the noise of an nth-order harmonic component by adjusting the phase difference Δφ. ij is set so that each Δφ ijthe following formula (10) is satisfied. Formula 10: π3<Δϕij<π

[0067] Fig. Figure 17 is a diagram that provides an example of a time waveform to illustrate a switching rectangular wave in the third embodiment. Fig. Figure 17 is also a diagram to illustrate six phase differences Δφ12, Δφ 23 , Δφ 31 , Δφ' 12 , Δφ' 23 and Δφ' 31 . Fig. Figure 18 is a diagram showing the six phase differences Δφ 12 , Δφ 23 , Δφ 31 , Δφ' 12 , Δ φ' 23 and Δφ' 31 out of Fig. 17 illustrated on the complex level. Fig. Figure 19 is a diagram showing an example of a time waveform of a switching square wave in a case where the frequency is variable. Fig. Figure 20 is a diagram showing an example of the time waveform of a switching square wave in a case where the frequency is fixed. In each of the Fig. 17, Fig. 19 and Fig. In diagram 20, the horizontal axis represents time and the vertical axis represents tension. Fig. 20 uses 30 kHz as a fixed switching frequency. The fixed switching frequency of 30 kHz is chosen to match the number of switching operations to the number of switching operations due to the three types of carrier frequencies in Fig. 17 to align and thus make the switching loss conditions comparable.

[0068] Fig. Figure 21 is a diagram that compares, with respect to peak detection, a frequency characteristic of electromagnetic noise in the case of using the switching square wave in the third embodiment, a frequency characteristic of electromagnetic noise in the case of using a switching square wave whose carrier frequency is fixed, and a frequency characteristic of electromagnetic noise in the case of using a switching square wave whose carrier frequency is variable. Fig. Figure 22 is a diagram that compares, with respect to average detection, a frequency characteristic of electromagnetic noise in the case of using the switching square wave in the third embodiment, a frequency characteristic of electromagnetic noise in the case of using the switching square wave whose carrier frequency is fixed, and a frequency characteristic of electromagnetic noise in the case of using the switching square wave whose carrier frequency is variable. Fig. 21 and Fig. In figure 22, the horizontal axis represents the frequency, while the vertical axis represents the noise level (noise voltage).

[0069] As in the upper areas of the Fig. 21 and Fig. As shown in Figure 22, it can be seen that in the third embodiment, the noise in a specific area within a band from 310 kHz to 400 kHz, including 330 kHz, is reduced compared to the case where the carrier frequency is fixed. Furthermore, as shown in the upper and lower sections in Fig. 21 and Fig. Figure 22 shows that, even in a case where the carrier frequency is variable, the harmonic component of 330 kHz is larger than in the third embodiment when the phase differences Δφ and Δφ' are fixed. That is, the method of the third embodiment is also effective in a case where the noise of a harmonic component of a certain order is reduced.

[0070] Fig. Figure 23 is a diagram illustrating an example of a hardware configuration for implementing the functions of the switching control units 1 and 1A according to the first to third embodiments. That is, at least some of the functions of the frequency adjustment unit 2, the phase shift adjustment unit 3, and the control signal generation unit 4 of the first to third embodiments can be implemented by a processor 97 that executes a program stored in a memory 98.

[0071] Examples of the processor 97 include a central processing unit (CPU, also called a processing unit, computing unit, microprocessor, microcomputer, processor, or digital signal processor (DSP)) and a low-intensity integration (LSI) system. Examples of memory 98 include random-access memory (RAM) and read-only memory (ROM).

[0072] In a case where at least one part of the functions of the frequency adjustment unit 2, the phase shift adjustment unit 3, and the control signal generation unit 4 of the first to third embodiments is implemented by the processor 97, that at least one part of the functions is implemented by a combination of the processor 97 and software, firmware, or software and firmware. The software or firmware is written as a program and stored in memory 98. Alternatively, the program stored in memory 98 can be said to cause a computer to execute at least one part of a procedure or method performed by the frequency adjustment unit 2, the phase shift adjustment unit 3, and the control signal generation unit 4 of the first to third embodiments.

[0073] Fig. Figure 24 is a diagram illustrating a further example of the hardware configuration for implementing the functions of the switching control units 1 and 1A according to the first to third embodiments. That is, the functions of the switching control unit 1 according to the first embodiment and of the switching control unit 1A according to the second and third embodiments can be implemented by a processing circuit 99, which is dedicated hardware.

[0074] The processing circuit 99 is, for example, a single circuit, a composite circuit, a programmed processor, a parallel programmed processor, an application-specific integrated circuit (ASIC), a field-programmable gate array (FPGA), or a combination thereof.

[0075] Regarding the functions of the switching control unit 1 according to the first embodiment and the switching control unit 1A according to the second and third embodiments, one set of functions can be implemented by dedicated hardware, while another set can be implemented by software or firmware. That is to say, one set of functions of the frequency adjustment unit 2, the phase shift adjustment unit 3, and the control signal generation unit 4 of the first to third embodiments can be implemented by the Fig. The processor 97 and the memory 98 shown in diagram 23 are implemented, and the remaining functions can be achieved by the components shown in diagram 23. Fig. The processing circuit shown in section 24 can be implemented in 99.

[0076] The configurations described in the above embodiments are merely examples and can be combined with other known technologies, and a portion of the configurations can be omitted or modified without deviating from their core message. List of reference symbols

[0077] 1, 1A Switching control unit; 2 Frequency adjustment unit; 3 Phase shift adjustment 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 Choke; 16 Diode; 17 Smoothing capacitor; 20 Inverter; 21 Inverter main circuit; 97 Processor; 98 Memory; 99 Processing circuit. QUOTES INCLUDED IN THE DESCRIPTION

[0000] This list of documents cited by the applicant was automatically generated and is included solely for the reader's convenience. The list is not part of the German patent or utility model application. The DPMA accepts no liability for any errors or omissions. Cited patent literature

[0000] JP 2006-288103

[0002] JP 2016-19322

[0002]

Claims

[1] Switching control unit that controls a switching operation performed by a switching element, wherein the switching control unit comprises: a frequency setting unit for setting a variety of carrier frequencies and a frequency change period; and a control unit for controlling a switching operation performed by the switching element by switching the plurality of types of carrier frequencies in the frequency change period, wherein the frequency change period is longer than a time width determined by the reciprocal of a resolution bandwidth, and Then, if an average number of switching operations in sections of the frequency change period is denoted by fave, an average number of switching operations in sections clipped with the time width is denoted by fw, the resolution bandwidth is denoted by RBW, and m is an integer of 2 or more, fw satisfies the following relationship: fave−RBW / 2 <fw<fave+RBW / 2. [2] Switching control device according to claim 1, wherein the average number of switching operations is calculated by the harmonic mean of the plurality of carrier frequency types. [3] Switching control unit according to claim 1 or 2, wherein the resolution bandwidth is 200 Hz, 1 kHz, 9 kHz, 10 kHz, 120 kHz or 1 MHz. [4] Switching control unit according to any one of claims 1 to 3, comprising the following: a phase shift adjustment unit, in order to then, if one of the multitude of carrier frequencies is a first carrier frequency, one of the multitude of carrier frequencies is different from the first carrier frequency, a second carrier frequency, one that differs from the first and second carrier frequencies, a third carrier frequency, and one that differs from the first, second, and The third carrier frequency differs, a fourth carrier frequency is, establishes a phase difference between the respective switching rectangular waves, which are determined by the first to fourth carrier frequencies. [5] Switching control unit according to claim 4, wherein the phase shift adjustment unit adjusts the phase difference so that the switching noise of a harmonic component generated by the switching process is reduced. [6] Switching control unit according to claim 5, wherein The frequency setting unit sets the multitude of carrier frequencies, the frequency change period and a duty cycle depending on the harmonic component and The phase shift adjustment unit adjusts the phase difference depending on the harmonic component. [7] Switching control device according to one of claims 4 to 6, wherein in a case where one phase is by φ i is designated as the phase based on time t i,on is calculated, at which the switching square wave, which is a signal waveform of a control signal for controlling the switching process, is switched on by an i-th frequency fi among the multitude of carrier frequencies, and the time t i,off , to which a switching square wave is switched off by the i-th frequency fi in the frequency change period, The phase shift adjustment unit adjusts the phase difference so that the absolute value of a phase difference between a phase φ i and a phase φ i +1 π / m or more and 3 π / m or less, i is an integer of 1 or more and m means a number of types of carrier frequencies. [8] Switching control unit according to claim 7, wherein The phase φi is defined by a formula φ i =πnt i,on / T+πnt i,off / T is defined n is an integer of 1 or more and represents the order of a harmonic component for which noise reduction is desired, and T represents the frequency change period. [9] Switching control device according to claim 7 or 8, wherein the phase difference between the phase φ i and the phase φ i +1 2π / m. [10] Power converter device comprising the following: the switching control unit according to one of claims 1 to 9; and a power conversion circuit that includes a switching element.

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