Switching power supply device and control device

Abstract

A switching power supply device is provided with: a switching circuit that transforms an input power by a switching operation in accordance with a pulse drive signal; a smoothing circuit in which capacitors connected in parallel are disposed at least on the output side of the switching circuit; and a control device that generates a pulse drive signal so that the output voltage of the smoothing circuit becomes a predetermined output target voltage, the control device being provided with: a voltage compensation unit that generates a control value that changes the duty ratio of the pulse drive signal so as to suppress the difference between the output voltage and the output target voltage; a current compensation unit that corrects the control value on the basis of a detection current at a prescribed location of the smoothing circuit; and a dummy capacitance unit that calculates, from the output voltage, a current correction amount based on a dummy capacitance generated by a dummy parallel element connected in parallel with the capacitor, and corrects the control value input to the current compensation unit.

Description

Technical Field

[0001] The present invention relates to a switching power supply device and a control device. Background Art

[0002] In recent years, various switching power supplies have been proposed (for example, refer to Patent Documents 1 to 3 and Non-Patent Document 1).

[0003] Prior Art Documents

[0004] Patent Documents

[0005] Patent Document 1: Japanese Unexamined Patent Application Publication No. 2011-254645

[0006] Patent Document 2: Japanese Unexamined Patent Application Publication No. 2017-200419

[0007] Patent Document 3: Japanese Unexamined Patent Application Publication No. 2022-91189

[0008] Non-Patent Documents

[0009] Non-Patent Document 1: Shinjiro Yokoo, Keiichiro Kondo, "Design Method of Damping Control System for Vector-Controlled Induction Motor Drive System in DC Electric Railway Vehicles", Transactions of the Institute of Electrical Engineers of Japan, D, The Institute of Electrical Engineers of Japan, June 1, 2015, Vol. 135, No. 6, p. 622-631 Summary of the Invention

[0010] Problems to be Solved by the Invention

[0011] When aiming to miniaturize and increase the efficiency of a switching power supply device, as one of the countermeasures, it is considered to use small and low-loss components for the components constituting the circuit. However, when such components are used in the smoothing circuit of the switching power supply device, due to the reduction in attenuation ability, for example, the waveform of the output voltage is likely to vibrate during load changes.

[0012] Therefore, the present application discloses a technique capable of stabilizing the output voltage of a switching power supply device.

[0013] Means for Solving the Problems

[0014] To solve the above problems, in the present invention, based on the output voltage, a current correction amount of a virtual capacitor generated by the virtual parallel component in the case where a virtual parallel component is provided in the smoothing circuit is calculated, and a control value that changes the duty ratio of the pulse drive signal is corrected.

[0015] Specifically, the present invention is a switching power supply device, comprising: a switching circuit that transforms input power through a switching operation corresponding to a pulse drive signal; a smoothing circuit that has capacitors connected in parallel at least on the output side of the switching circuit; and a control device that generates a pulse drive signal in such a way that the output voltage of the smoothing circuit becomes a specified output target voltage. The control device includes: a voltage compensation unit that generates a control value for changing the duty ratio of the pulse drive signal to suppress the difference between the output voltage and the output target voltage; a current compensation unit that corrects the control value based on a detected current at a specified part of the smoothing circuit; and a virtual capacitance unit that calculates a current correction amount based on a virtual capacitance according to the output voltage and corrects the control value input to the current compensation unit. The virtual capacitance is generated by a virtual parallel component connected in parallel with the capacitor.

[0016] According to such a switching power supply device, the control value for changing the duty ratio of the pulse drive signal is corrected to include a virtual capacitance generated by a virtual parallel component that does not actually exist in the smoothing circuit. Therefore, even if the capacitors actually present in the smoothing circuit use small and low-loss components, the output voltage can be stabilized without reducing the attenuation ability.

[0017] In addition, the virtual parallel component may also include a virtual capacitor and a virtual resistor connected in parallel with the capacitor. If the current correction amount based on the virtual capacitance generated by such a virtual parallel component is calculated according to the output voltage and the control value input to the current compensation unit is corrected, the output voltage can be stabilized.

[0018] Furthermore, in the virtual admittance of the virtual capacitance unit for correcting the control value, a filter that reduces the gain in the high-frequency domain may also be included. If such a filter is included, the control value can be corrected appropriately.

[0019] Alternatively, the smoothing circuit may include an inductor connected to the switching circuit, and the control device may further have a virtual inductance unit that calculates a voltage correction amount based on a virtual inductance according to the detected current and corrects the output target voltage input to the voltage compensation unit. The virtual inductance is generated by a virtual series component connected in series with the inductor. According to such a switching power supply device, the control value for changing the duty ratio of the pulse drive signal is corrected to include a virtual inductance generated by a virtual series component that does not actually exist in the smoothing circuit. Therefore, even if the inductor actually present in the smoothing circuit uses a small and low-loss inductor, the output voltage can be stabilized without reducing the attenuation ability.

[0020] In addition, the virtual series element may also include a virtual inductor and a virtual resistor connected in series with the inductor. If the voltage correction amount of the virtual inductor generated based on such a virtual parallel element is calculated according to the output voltage operation and the output target voltage input to the voltage compensation unit is corrected, the output voltage can be stabilized.

[0021] In addition, in the virtual impedance for correcting the control value in the virtual inductor unit, a filter for reducing the gain in the high-frequency region may also be included. If such a filter is included, the control value can be corrected appropriately.

[0022] In addition, the current compensation unit may also correct the control value based on the detected current averaged by a filter that averages the current. If it is such a current compensation unit, the tolerance of the detected current to noise is improved.

[0023] In addition, the switching circuit and the smoothing circuit may also form a single-phase or three-phase inverter circuit. If it is a switching power supply device in which such an inverter circuit is formed by the switching circuit and the smoothing circuit, the output voltage output to the load can be stabilized.

[0024] In addition, the present invention can also be understood from the perspective of the control device for the switching power supply device. For example, the present invention may also be a control device for a switching power supply device, which has: a switching circuit that transforms the input power through a switching operation corresponding to a pulse drive signal; and a smoothing circuit that configures an inductor connected in series and a capacitor connected in parallel on the output side of the switching circuit. The control device for the switching power supply device has a control unit that generates a pulse drive signal in such a way that the output voltage of the smoothing circuit becomes a specified output target voltage. The control unit has: a voltage compensation unit that generates a control value that changes the duty ratio of the pulse drive signal to suppress the difference between the output voltage and the output target voltage; a current compensation unit that corrects the control value based on the detected current at a specified part of the smoothing circuit; and a virtual capacitor unit that calculates the current correction amount based on the virtual capacitor according to the output voltage and corrects the control value input to the current compensation unit. The virtual capacitor is generated by a virtual parallel element connected in parallel with the capacitor.

[0025] Advantages of the Invention

[0026] If it is the said switching power supply device and control device, the output voltage of the switching power supply device can be stabilized. Description of the Drawings

[0027] Figure 1 It is a schematic diagram of the circuit structure implemented by the switching power supply device of the application example.

[0028] Figure 2 It is a block diagram of the control system of the switching power supply device.

[0029] Figure 3 It is the circuit structure diagram of a three-phase inverter.

[0030] Figure 4 It is a general matching model after dq transformation in a three-phase inverter.

[0031] Figure 5 It is a matching model when a load is set in a three-phase inverter.

[0032] Figure 6 It is a diagram showing the small-signal model of the d-axis in a three-phase inverter.

[0033] Figure 7 It is a block diagram of a control system that applies the virtual capacitor section in the embodiment to the basic structure of current-mode control.

[0034] Figure 8 It is a diagram showing the verification result in a three-phase inverter.

[0035] Figure 9 It is a diagram showing the verification result in a single-phase inverter. Detailed Embodiment

[0036] <Application Example>

[0037] Figure 1 It is a schematic diagram of the circuit structure implemented by the switching power supply device in the application example. The switching power supply device 1 in this application example is a converter having a switching circuit 2, a smoothing circuit 3, and a control device 6, which converts and outputs the voltage of the input power to the switching power supply device 1. The switching circuit 2 transforms the input power through a switching operation corresponding to the pulse drive signal generated by the control device 6. The smoothing circuit 3 is a circuit in which an inductor 4 is connected in series and a capacitor 5 is connected in parallel on the output side of the switching circuit 2, and smooths the output current of the switching circuit 2 through the inductor 4 and the capacitor 5, thereby removing high-order harmonic components included in the output current of the switching circuit 2, etc.

[0038] In addition, in the switching power supply device of this application example, through the arithmetic processing in the control device 6, such as Figure 1As shown, a virtual resistor V1, a virtual inductor V2, a virtual capacitor V3, a virtual ESR V4 (ESR: equivalent series resistance), and a virtual dummy resistor V5 are hypothetically formed. The inductor 4 and the capacitor 5 are components of actual existing components. In contrast, the virtual resistor V1, the virtual inductor V2, the virtual capacitor V3, the virtual ESR V4, and the virtual dummy resistor V5 are not components of actual existing components. The virtual resistor V1, the virtual inductor V2, the virtual capacitor V3, and the virtual ESR V4 are components virtually implemented in the operation of the control device 6 that controls the switching operation of the switching circuit 2. Therefore, in order to easily distinguish between actual existing components and non-actual existing components, in Figure 1 the part composed of the inductor 4 and the capacitor 5 is regarded as the actual component RP, the part composed of the virtual resistor V1 and the virtual inductor V2 is regarded as the virtual inductor VLR, and the part composed of the virtual capacitor V3, the virtual ESR V4, and the virtual dummy resistor V5 is regarded as the virtual capacitor VCR.

[0039] Figure 2 is a block diagram of the control system of the switching power supply device 1. Figure 2 The block diagram shown is implemented by the control action of the control device 6. The control object B1 represents the whole of the switching circuit 2 and the smoothing circuit 3. The control device 6 generates a pulse drive signal for the switching circuit 2 in such a way that the output voltage of the switching power supply device 1 becomes a specified output target voltage. In addition, in the control system of the switching power supply device 1, current mode control is implemented by using the current flowing through the smoothing circuit 3.

[0040] In addition, in the control system of the switching power supply device 1, there is provided a virtual inductor section B9 for implementing Figure 1 the virtual inductor VLR shown. The virtual inductor section B9 has a filter B4 and a subtractor B6. In the control system of the switching power supply device 1, since such a virtual inductor section B9 is provided, even though it does not actually exist, a control value as if the virtual inductor VLR formed by the virtual resistor V1 and the virtual inductor V2 actually exists is calculated and reflected in the change of the duty ratio of the pulse drive signal. Therefore, even if a component with a relatively small capacitance is used as the inductor 4 installed in the smoothing circuit 3, the reduction in attenuation ability caused thereby can be compensated by the virtual inductor section B9.

[0041] In addition, in the control system of the switching power supply device 1, there is provided a device for implementing Figure 1The virtual capacitance section B10 of the virtual capacitance VCR shown. The virtual capacitance section B10 has a filter B5 and a subtracter B8. Since such a virtual capacitance section B10 is provided in the control system of the switching power supply device 1, a control value is calculated as if the virtual capacitance VCR formed by the virtual capacitor V3, the virtual ESR V4, and the virtual dummy resistor V5 actually exists, even though it does not actually exist, and is reflected in the change in the duty ratio of the pulse drive signal. Therefore, even if a component with a relatively small capacitance is used as the capacitor 5 installed in the smoothing circuit 3, the reduction in the attenuation ability caused thereby can be compensated for by the virtual capacitance section B10.

[0042] In the switching power supply device 1 according to this application example, even if the components installed in the smoothing circuit 3 are small-sized and low-loss components, a control value can be calculated through the operation in the control device 6 as if a virtual inductor VLR and a virtual capacitance VCR actually exist in the smoothing circuit 3, and is reflected in the change in the duty ratio of the pulse drive signal of the switching circuit 2. Therefore, even if small-sized and low-loss components are used for the inductor 4 and the capacitor 5 constituting the smoothing circuit 3 in order to miniaturize and increase the efficiency of the switching power supply device 1, the waveform vibration of the output voltage e o can be suppressed during load variations. Therefore, high-frequency vibrations superimposed on the output voltage waveform can be prevented.

[0043] In addition, in this application example, a method of providing a virtual inductor section B9 and a virtual capacitance section B10 in the control system to reproduce the virtual inductor VLR and the virtual capacitance VCR in the smoothing circuit 3 is illustrated, but the switching power supply device 1 is not limited to such a method. The switching power supply device 1 may also be, for example, a method in which the virtual inductor section B9 is omitted from the control system and the virtual inductor VLR is not reproduced in the smoothing circuit 3 but only the virtual capacitance VCR is reproduced.

[0044] <Embodiment>

[0045] Hereinafter, the embodiment will be described. The embodiment shown below is one mode of the present application and does not limit the technical scope of the present application.

[0046] Refer to the one used to illustrate the above application example Figure 1The circuit structure of the switching power supply device according to this embodiment will be described. The switching power supply device 1 according to this embodiment is a converter including a switching circuit 2, a smoothing circuit 3, and a control device 6 as described in the above application example, which converts the voltage of the input power of the switching power supply device 1 and outputs it. The switching circuit 2 transforms the input power through a switching operation corresponding to the pulse drive signal generated by the control device 6. The smoothing circuit 3 is a circuit in which an inductor 4 connected in series and a capacitor 5 connected in parallel are arranged on the output side of the switching circuit 2. The inductor 4 and the capacitor 5 smooth the output current of the switching circuit 2, thereby removing high-order harmonic components and the like included in the output current of the switching circuit 2. In the switching power supply device according to this embodiment, as described in the application example, a virtual resistor V1, a virtual inductor V2, a virtual capacitor V3, a virtual ESR V4, and a virtual dummy resistor V5 are virtually formed.

[0047] Next, referring to the Figure 2 for explaining the above application example, the control system of the switching power supply device 1 according to this embodiment will be described. In the switching power supply device 1 according to this embodiment, the control device 6 generates a pulse drive signal for the switching circuit 2 in such a way that the output voltage e o of the switching power supply device 1 becomes a specified output target voltage e oref . That is, the control device 6 calculates the difference between the output voltage e o obtained by a voltmeter that detects the voltage between the output terminals of the switching power supply device 1 and the specified output target voltage e oref through a subtractor B7. Then, the control device 6 processes the difference calculated by the subtractor B7 using a voltage compensator B2 to correct the difference. By using the corrected difference for the generation of the pulse drive signal of the switching circuit 2, a basic control system for making the output voltage e o of the switching power supply device 1 become the specified output target voltage e oref is realized.

[0048] In addition, in the control system of the switching power supply device 1 according to this embodiment, current-mode control is realized by using the output current i o obtained by an ammeter that detects the current flowing through the smoothing circuit 3. Specifically, the difference between the difference output from the voltage compensator B2 and the output current i o is calculated through a subtractor B8. Then, the control device 6 processes the difference calculated by the subtractor B8 using a current compensator B3 to correct the difference. By using the corrected difference as a control value for changing the duty ratio of the pulse drive signal, the use of the output current i oCurrent mode control. Thereby, a control system with excellent line regulation and easy phase compensation is achieved. In addition, as the current for current mode control, the output current i of the switching power supply device 1 is illustrated here o , but instead of the output current of the switching power supply device 1, for example, the current of the inductor 4 can be used.

[0049] In addition, in the control system of the switching power supply device 1 of the present embodiment, as also described in the application example, there is provided a virtual inductor section B9 for realizing Figure 1 the virtual inductor VLR shown. The virtual inductor section B9 has a filter B4 and a subtractor B6. The filter B4 corrects the output current i o . The filter B4 reproduces the virtual inductor VLR connected in series with the output of the switching circuit 2. Therefore, when the virtual impedance of the virtual inductor VLR is Z vl , the virtual inductor V2 of the virtual inductor VLR is the inductance L V and ESRr vl , and the virtual resistor V1 of the virtual inductor VLR is R dp , it is represented by the following mathematical formula 1. In the following mathematical formula 1, f vl is a filter for the purpose of reducing the gain in the high frequency range, and R dp is the voltage drop.

[0050] [Mathematical formula 1]

[0051]

[0052] The subtractor B6 calculates the difference between the output target voltage e oref and the output of the filter B4, and generates correction information e drp . As described above, for easy understanding, it is illustrated that the subtractor B7 calculates the difference between the output voltage e o and the specified output target voltage e oref , but more accurately, the subtractor B7 calculates the difference between the output voltage e o and the correction information e drp . Then, the difference calculated by the subtractor B7 is input to the voltage compensator B2. Since such a virtual inductor section B9 is provided in the control system of the switching power supply device 1, although it does not actually exist, a control value as if the virtual inductor VLR formed by the virtual resistor V1 and the virtual inductor V2 actually exists is calculated and reflected in the change of the duty ratio of the pulse drive signal. Therefore, even if a component with a relatively small capacitance is used as the inductor 4 installed in the smoothing circuit 3, the reduction in attenuation ability caused thereby can be compensated by the virtual inductor section B9.

[0053] In addition, in the control system of the switching power supply device 1 according to the present embodiment, as described in the application example, a virtual capacitor unit B10 for implementing the virtual capacitor VCR shown in Figure 1 is provided. The virtual capacitor unit B10 includes a filter B5 and a subtractor B8. The filter B5 corrects the output voltage e o . The filter B5 reproduces the virtual capacitor VCR connected in parallel with the output of the switching circuit 2. Therefore, when the virtual admittance of the virtual capacitor VCR is Y VC , the virtual capacitor V3 of the virtual capacitor VCR is capacitance C V , the virtual ESR V4 of the virtual capacitor VCR is r vc , and the virtual dummy resistor V5 of the virtual capacitor VCR is R dm , it is represented by the following mathematical formula 2. In the following mathematical formula 2, f vc is a filter for reducing the gain in the high-frequency range, and R dm improves the damping factor.

[0054] [Mathematical formula 2]

[0055]

[0056] The subtractor B8 calculates the difference obtained by subtracting the output current i o and the output of the filter B5 from the output of the voltage compensator B2. Then, the difference calculated by the subtractor B8 is input to the current compensator B3. Since such a virtual capacitor unit B10 is provided in the control system of the switching power supply device 1, a control value as if the virtual capacitor VCR formed by the virtual capacitor V3, the virtual ESR V4, and the virtual dummy resistor V5 actually exists is calculated, although it does not actually exist, and is reflected in the change in the duty ratio of the pulse drive signal. Therefore, even if a capacitor with a relatively small capacitance is used as the capacitor 5 installed in the smoothing circuit 3, the virtual capacitor unit B10 can compensate for the resulting reduction in attenuation ability.

[0057] According to the switching power supply device 1 of the present embodiment, even if the elements installed in the smoothing circuit 3 are small and low-loss elements, a control value as if a virtual inductor VLR and a virtual capacitor VCR actually exist in the smoothing circuit 3 can be calculated through the operation in the control device 6 and reflected in the change in the duty ratio of the pulse drive signal of the switching circuit 2. Therefore, even if small and low-loss elements are used for the inductor 4 and the capacitor 5 constituting the smoothing circuit 3 in order to miniaturize and increase the efficiency of the switching power supply device 1, the waveform of the output voltage e o is not likely to vibrate when the load changes. Therefore, high-frequency vibrations superimposed on the output voltage waveform can be suppressed.

[0058] In addition, the switching power supply device 1 of the present embodiment may also be a mode in which, as described in the application example, for example, the virtual inductor section B9 is omitted from the control system, and only the virtual capacitor VCR is reproduced in the smoothing circuit 3 without reproducing the virtual inductor VLR.

[0059] <Example 1>

[0060] Hereinafter, an example in the case where the virtual capacitor VCR in the above-described embodiment is applied to the voltage control of a three-phase inverter will be described.

[0061] Figure 3 is a circuit structure diagram of a three-phase inverter. Hereinafter, the application of the above-described embodiment to Figure 3 the three-phase inverter shown will be studied. As Figure 3 shown, the three-phase inverter includes: a switching circuit having a total of six switches for performing switching operations in each of the U-phase, V-phase, and W-phase; and a smoothing circuit provided in each phase. The resistor R is a load. Figure 4 is a general matching model after dq transformation in a three-phase inverter. As Figure 4 shown, the general matching model after dq transformation in a three-phase inverter is voltage mode control, and the above-described embodiment cannot be applied to this matching model. Therefore, in order to apply the above-described embodiment to a three-phase inverter, the current mode control of the three-phase inverter is studied.

[0062] Figure 5 is a matching model in the case where a load is provided in a three-phase inverter. Figure 5 The matching model shown is expressed using the concept of a motor. In Figure 5 the matching model shown, the model is not suitable for current mode control, so it is changed to a form suitable for current mode control. In Figure 5 the matching model shown, V cd , V cq , i d and i q The state equations with these as state variables are represented by the following mathematical formula 3.

[0063] [Mathematical formula 3]

[0064]

[0065] In this case, the characteristic equation becomes a fourth-order function of s and is difficult to analyze. Therefore, regarding this mathematical formula 3, the decoupling of the dq axes is performed in the same way as the motor. That is, this mathematical formula 3 is transformed into the following mathematical formula 4.

[0066] [Mathematical formula 4]

[0067]

[0068] When the third term on the right side of the mathematical formula 4 is considered as interference and canceled by feedforward, the dq axes are made interference-free as shown in the following two mathematical formulas 5 and 6.

[0069] [Mathematical formula 5]

[0070]

[0071] [Mathematical formula 6]

[0072]

[0073] In addition, the output equation is represented by the following mathematical formula 7.

[0074] [Mathematical formula 7]

[0075]

[0076] In addition, when α is used as the control input, the input-output relationship is defined by the following mathematical formula 8.

[0077] [Mathematical formula 8]

[0078]

[0079] The third term on the right side of each of the mathematical formulas 5 and 6 is the term canceled by feedforward and is considered as interference. Except for this interference term, it becomes the same state equation as that of the buck converter. Therefore, when the small-signal model of the d-axis is derived from the mathematical formulas 5 and 7, the following mathematical formulas 9 and 10 are obtained.

[0080] [Mathematical formula 9]

[0081] Δv od =G αvo ·Δα d +G vivo ·ΔV in -G Rvo ·ΔR-(W vi ·Δi q +W vv ·Δv oq )-z o ·Δi od …(Mathematical formula 9)

[0082] [Mathematical formula 10]

[0083] Δi d =G αi ·Δα d +G vii ·ΔV in +GRi ·ΔR + G ioi ·Δi od -(W ii ·Δi q + W iv ·Δv oq )…(Mathematical formula 10)

[0084] Among them, the coefficients of the above mathematical formula are as follows.

[0085] [Mathematical formula 11]

[0086]

[0087] Similarly, when deriving the small-signal model of the q-axis, the following Mathematical formula 12 and Mathematical formula 13 are obtained.

[0088] [Mathematical formula 12]

[0089] Δv oq = G αvo ·Δα d + G vivo ·ΔV in - G Rvo ·ΔR-(W vi ·Δi d + W vv ·Δv od )…(Mathematical formula 12)

[0090] [Mathematical formula 13]

[0091] Δi q = G αi ·Δα d + G vii ·ΔV in + G Ri ·ΔR-(W ii ·Δi d + W iv ·Δv od )…(Mathematical formula 13)

[0092] Comparing Mathematical formula 9 and Mathematical formula 10, Mathematical formula 12 and Mathematical formula 13, it can be seen that if the subscripts d and q are swapped, the two are the same formula, and of course the structure of the control system is also the same. Therefore, a small-signal model of a three-phase inverter focusing only on the d-axis is shown. Figure 6 It is a diagram showing the small-signal model of the d-axis in a three-phase inverter.

[0093] In the first embodiment, in the control system of this model with a current-mode control as the basic structure, the virtual capacitor part R10 of the reproduced virtual capacitor VCR in the above-described embodiment is applied. Figure 7It is a block diagram of a control system that applies the virtual capacitor section R10 in the embodiment to the basic structure of current mode control. The basic structure is the same as Figure 2 However, in this Embodiment 1, average current mode control is used according to the actual system, so an average current filter Fi is provided. As a result, the tolerance of the detected current to noise is improved. In Figure 7 , C v corresponds to the voltage compensator B2 in the above embodiment, and C i corresponds to the current compensator B3 in the above embodiment, and Y VC corresponds to the filter B5 in the above embodiment. The average current filter Fi is represented by the following Mathematical Formula 14, and C i is represented by the following Mathematical Formula 15, and C v is represented by the following Mathematical Formula 16.

[0094] [Mathematical Formula 14]

[0095]

[0096] [Mathematical Formula 15]

[0097]

[0098] [Mathematical Formula 16]

[0099]

[0100] Figure 8 It is a diagram showing the verification results in a three-phase inverter. In this verification, as the control method of the three-phase inverter, in addition to this Embodiment 1 in which the virtual capacitor VCR is combined in current mode control, as a comparative example, Comparative Example 1 of voltage mode control and Comparative Example 2 of current mode control were prepared, and simulations related to the respective operations when the resistive load suddenly changes from 100% to 1% and when the rectifier load were performed. The specifications of the three-phase inverter are 200Vac / 10kVA (rated load resistance R rate : 4.08 Ω), Figure 3 The circuit parameters and the like of the respective symbols shown are as follows.

[0101] Input voltage: 400V

[0102] Output line-to-line voltage: 200Vrms

[0103] Switching frequency fsw: 20kHz

[0104] Reference frequency f: 50Hz

[0105] L = 250 [μH]

[0106] rl = 50 [mΩ]

[0107] C = 36 [μF] (star connection)

[0108] rc = 10 [mΩ]

[0109] Sampling frequency: 40 kHz

[0110] Comparison Figure 8 From the waveforms of comparison, compared with Comparative Example 1 and Comparative Example 2, in this Example 1, the vibration decays rapidly when the load changes suddenly, and the output is stable. In addition, it can be seen that the output is also stable when the rectifier is loaded. Therefore, according to the verification results, if the above-mentioned implementation method is applied to a three-phase inverter, even if the components constituting the smoothing circuit are small and low-loss components, compared with the general voltage-mode control and current-mode control cases, the output voltage can be stabilized. Therefore, if this Example 1 is used in the electrical equipment in the user's area, for example, when the external power supply is lost due to a power system outage or the like and the power is supplied to the area through a battery or the like during independent operation, even when the electrical load in the area changes suddenly, the power can be continuously supplied to the area at a stable voltage.

[0111] <Example 2>

[0112] Figure 9 It is a diagram showing the verification results in a single-phase inverter. The above-mentioned implementation method can be applied not only to the three-phase inverter shown as Example 1, but also to a single-phase inverter, for example. In this verification, the case where the virtual capacitor VCR in the above-mentioned implementation method is applied to the voltage control of a single-phase inverter is taken as Example 2, and a single-phase inverter with normal current-mode control without applying the above-mentioned implementation method is taken as Comparative Example 3, and simulations are carried out, but the details such as the study of the supporting model and the simulation conditions are omitted.

[0113] Comparison Figure 9 From the waveforms of comparison, compared with Comparative Example 3, in this Example 2, the vibration decays rapidly when the load changes suddenly, and the output is stable. In addition, it can be seen that the output is also stable when the rectifier is loaded. Therefore, according to the verification results, when the above-mentioned implementation method is applied to a single-phase inverter, similar to Example 1 above, the output voltage can be stabilized. Therefore, in this Example 2, similar to Example 1, for example, when the external power supply is lost due to a power system outage or the like and the power is supplied to the area through a battery or the like during independent operation, even when the electrical load in the area changes suddenly, the power can be continuously supplied to the area at a stable voltage.

[0114] <Other Variants>

[0115] In addition to the three-phase inverter of Embodiment 1 and the single-phase inverter of Embodiment 2, the above-described embodiments can also be applied to various power supply devices such as DC-DC converters assembled in various electronic devices and inverters that control various drive sources.

[0116] Furthermore, the above-described embodiments can be appropriately modified within the scope of not changing the gist disclosed in the present application. For example, in the above, the circuit structure of a buck converter having a smoothing circuit 3 in which an inductor 4 connected in series and a capacitor 5 connected in parallel are arranged on the output side of the switching circuit 2 is illustrated. However, the above-described embodiments can be modified, for example, into a buck-boost converter having a smoothing circuit in which an inductor connected in parallel and a capacitor connected in parallel are arranged on the output side of the switching circuit, or a boost converter having a smoothing circuit in which an inductor is arranged on the power supply side with respect to the switching element of the switching circuit and a capacitor is arranged in parallel on the output side of the switching circuit.

[0117] In addition, the present application includes the following supplementary notes.

[0118] <Supplementary Note 1>

[0119] A switching power supply device includes: a switching circuit (2) that transforms input power through a switching operation corresponding to a pulse drive signal; a smoothing circuit (3) that has at least a capacitor connected in parallel arranged on the output side of the switching circuit; and a control device (6) that generates the pulse drive signal in such a manner that the output voltage of the smoothing circuit becomes a specified output target voltage. The control device includes: a voltage compensation unit (B2) that generates a control value for changing the duty ratio of the pulse drive signal to suppress the difference between the output voltage and the output target voltage; a current compensation unit (B3) that corrects the control value based on a detected current at a specified part of the smoothing circuit; and a virtual capacitor unit (B10) that calculates a current correction amount based on a virtual capacitor according to the output voltage and corrects the control value input to the current compensation unit. The virtual capacitor is generated by a virtual parallel element connected in parallel with the capacitor.

[0120] Reference Signs Explanation

[0121] 1: Switching power supply device;

[0122] 2: Switching circuit;

[0123] 3: Smoothing circuit;

[0124] 4: Inductor;

[0125] 5: Capacitor;

[0126] 6: Control device;

[0127] B1: Controlled object;

[0128] B2: Voltage compensator;

[0129] B3: Current compensator;

[0130] B4: Filter;

[0131] B5: Filter;

[0132] B6: Subtractor;

[0133] B7: Subtractor;

[0134] B8: Subtractor;

[0135] B9: Virtual inductor section;

[0136] B10: Virtual capacitor section;

[0137] V1: Virtual resistor;

[0138] V2: Virtual inductor;

[0139] V3: Virtual capacitor;

[0140] V4: Virtual ESR;

[0141] V5: Virtual dummy resistor;

[0142] RP: Actual component;

[0143] VLR: Virtual inductor;

[0144] VCR: Virtual capacitor.

Claims

1. A switching power supply device, comprising: A switching circuit that transforms input power through a switching operation corresponding to a pulse drive signal; A smoothing circuit that disposes capacitors in parallel at least on the output side of the switching circuit; And A control device that generates the pulse drive signal in such a manner that the output voltage of the smoothing circuit becomes a specified output target voltage, The control device comprising: A voltage compensation unit that generates a control value for changing the duty ratio of the pulse drive signal to suppress the difference between the output voltage and the output target voltage; A current compensation unit that corrects the control value based on a detected current at a specified part of the smoothing circuit; And A virtual capacitance unit that calculates a current correction amount based on a virtual capacitance according to the output voltage and corrects the control value input to the current compensation unit, where the virtual capacitance is generated by a virtual parallel element in parallel with the capacitor.

2. The switching power supply device according to claim 1, wherein The virtual parallel element includes a virtual capacitor and a virtual resistor in parallel with the capacitor.

3. The switching power supply device according to claim 1 or 2, wherein A filter for reducing the gain in the high-frequency domain is included in the virtual admittance used by the virtual capacitance unit for correcting the control value.

4. The switching power supply device according to claim 1, wherein The smoothing circuit includes an inductor connected to the switching circuit, The control device further has a virtual inductance unit that calculates a voltage correction amount based on a virtual inductance according to the detected current and corrects the output target voltage input to the voltage compensation unit, where the virtual inductance is generated by a virtual series element in series with the inductor.

5. The switching power supply device according to claim 4, wherein The virtual series element includes a virtual inductor and a virtual resistor in series with the inductor.

6. The switching power supply device according to claim 4 or 5, characterized in that A filter for reducing the gain in the high-frequency domain is included in the virtual impedance used by the virtual inductance unit for correcting the control value.

7. The switching power supply device according to claim 1, characterized in that The current compensation unit corrects the control value based on the detected current averaged by a filter for averaging the current.

8. The switching power supply device according to claim 1, wherein The switching circuit and the smoothing circuit form a single-phase or three-phase inverter circuit.

9. A control device for a switching power supply device, The switching power supply device comprising: A switching circuit that transforms input power through a switching operation corresponding to a pulse drive signal; And A smoothing circuit that disposes capacitors in parallel at least on the output side of the switching circuit, wherein The control device for the switching power supply device has a control unit that generates the pulse drive signal in such a manner that the output voltage of the smoothing circuit becomes a specified output target voltage, The control unit comprising: A voltage compensation unit that generates a control value for changing the duty ratio of the pulse drive signal to suppress the difference between the output voltage and the output target voltage; A current compensation unit that corrects the control value based on a detected current at a specified part of the smoothing circuit; and A virtual capacitor unit that calculates a current correction amount based on a virtual capacitor according to the output voltage and corrects the control value input to the current compensation unit, where the virtual capacitor is generated by a virtual parallel element connected in parallel with the capacitor.

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