Power converter

Abstract

This method reduces voltage ripple in power converters using a technique different from conventional methods. [Solution] The power conversion device (1) includes a DC / DC converter (DCDC1) and a smoothing capacitor (e.g., capacitor C) connected to the DC / DC converter (DCDC1). dc The system comprises a smoothing capacitor, a compensation circuit (INV1) connected to the smoothing capacitor, a control device (e.g., a compensation circuit control device CON1) for controlling the compensation circuit (INV1), and a voltage sensor (VT1) for detecting the voltage of the smoothing capacitor. The control device controls the compensation circuit (INV1) based on the voltage detected by the voltage sensor (VT1) so that the compensation circuit (INV1) outputs a compensation signal that at least partially cancels out the voltage ripple in the smoothing capacitor.

Description

[Technical Field]

[0001] One aspect of the present invention relates to a power conversion device. [Background technology]

[0002] Various technologies related to power conversion devices have been proposed. For example, Non-Patent Document 1 below describes a method for compensating for ripple in the input voltage of a DAB (Dual Active Bridge) converter using a DC active filter. A DAB converter is an example of a power conversion device. [Prior art documents] [Non-patent literature]

[0003] [Non-Patent Document 1] "Ripple Voltage Compensation of DAB Converter Using DC Active Filter," Yoshinori Nagamine, Hiroaki Yamada, Kensuke Shimizu, and Yuri Takayama, Proceedings of the 2023 Institute of Electrical Engineers of Japan, Industrial Applications Division Conference, Paper No. 1-34. [Overview of the project] [Problems that the invention aims to solve]

[0004] An object of one aspect of the present invention is to reduce voltage ripple in a power conversion device by a method different from conventional methods. [Means for solving the problem]

[0005] A power conversion device according to one aspect of the present invention comprises a DC / DC converter, a smoothing capacitor connected in series with the DC / DC converter, a compensation circuit connected to the smoothing capacitor, a control device for controlling the compensation circuit, and a voltage sensor for detecting the voltage of the smoothing capacitor. The control device controls the compensation circuit based on the voltage detected by the voltage sensor so that the compensation circuit outputs a compensation signal that at least partially cancels out the voltage ripple in the smoothing capacitor. [Effects of the Invention]

[0006] According to one aspect of the present invention, voltage ripple in a power converter can be reduced by a method different from the conventional one. [Brief explanation of the drawing]

[0007] [Figure 1] A schematic example of the configuration of the power conversion device in Embodiment 1 is shown below. [Figure 2] This shows an example of the configuration of a compensation circuit in a power converter. [Figure 3] A more detailed example of the configuration of a power conversion device is shown below. [Figure 4] An example of a control block in a compensation circuit control device for a power converter is shown. [Figure 5] A schematic representation of the simulation model in Embodiment 1 is shown below. [Figure 6] An example of the simulation results is shown. [Figure 7] The results of the FFT analysis corresponding to the example in Figure 6 are shown. [Figure 8] Here is another example of the simulation results. [Figure 9] The results of the FFT analysis corresponding to the example in Figure 8 are shown. [Figure 10] This shows an example of the configuration of the main circuit section of the power converter in Embodiment 2. [Figure 11] This shows an example of the configuration of the main circuit section of the power converter in Embodiment 3. [Modes for carrying out the invention]

[0008] [Embodiment 1] The power converter 1 of Embodiment 1 will be described below. For the sake of clarity, components having the same function as those described in Embodiment 1 will be denoted by the same reference numerals in subsequent embodiments, and their descriptions will not be repeated. Also, for the sake of simplification, explanations of matters similar to those in the publicly known art will be omitted as appropriate.

[0009] Each component and each numerical value described in this specification are merely illustrative examples unless otherwise specifically inconsistent. Therefore, for example, unless there is no content contradiction, the positional relationship and connection relationship of each component are not limited to the examples in each figure. In this specification, unless there is no content contradiction, the description of "connected" means "electrically connected".

[0010] (Configuration example of the power conversion device 1) FIG. 1 schematically shows a configuration example of the power conversion device 1. The power conversion device 1 in the example of FIG. 1 includes a main circuit section 10 and a compensation circuit control device CON1. The main circuit section 10 includes a DC / DC converter DCDC1 and a capacitor C[[ID=捌]]

[0013] and a compensation circuit INV1.

[0011] Capacitor C dc is a smoothing capacitor connected to the DC / DC converter DCDC1. Specifically, capacitor C dc is connected to the primary side of the DC / DC converter DCDC1. Capacitor C dc may also be referred to as a smoothing capacitor for the DC / DC converter.

[0012] The type of the DC / DC converter DCDC1 is not particularly limited. Therefore, the DC / DC converter DCDC1 in this specification is not limited to a DAB converter. The DC / DC converter DCDC1 can convert an input DC voltage into another DC voltage and can be connected to the capacitor C dc as long as it can be connected.

[0013] In the example of FIG. 1, the primary side of the DC / DC converter DCDC1 is connected to a DC power supply V dc1 . The DC power supply V dc1 may also be referred to as the primary side DC power supply of the DC / DC converter. On the other hand, the secondary side of the DC / DC converter DCDC1 is connected to a DC power supply V dc1 different from the DC power supply V dc2 . The DC power supply V dc2This may also be referred to as the secondary DC power supply of a DC / DC converter.

[0014] As an example, DC power supply V dc2 This can be any type of battery. According to the DC / DC converter DCDC1, for example, a DC power supply V dc1 Converts one DC voltage to another DC voltage, and uses that other DC voltage to power a DC power supply as a battery V dc2 It can be charged.

[0015] Voltage conversion in the DC / DC converter DCDC1 is performed by switching a switching element (not shown) within the DC / DC converter DCDC1. This switching may cause ripple in various parts connected to the DC / DC converter DCDC1. This ripple may adversely affect various parts related to the DC / DC converter DCDC1. Therefore, in order to reduce this ripple, the above-mentioned capacitor C dc However, it is provided as a smoothing capacitor.

[0016] However, capacitor C dc Since it is connected to the DC / DC converter DCDC1, capacitor C dc Voltage ripple can also occur in capacitor C. dc The voltage ripple that occurs in such a situation is, for example, the voltage of a DC power supply such as a battery. dc2 This could have adverse effects.

[0017] As an example, the voltage ripple in question is a DC power supply V dc2 This may adversely affect the charge and discharge control. Also, the DC power supply V dc2 If such a device is installed within a solar power generation system, the resulting voltage ripple may adversely affect the MPPT (Maximum Power Point Tracking) control in the solar power generation system.

[0018] From this, we can see that capacitor C dcIt is desirable to reduce the voltage ripple in this region. Therefore, in the example shown in Figure 1, capacitor C dc A compensation circuit INV1 is provided in series with the capacitor C. dc It outputs a compensation signal that at least partially cancels out the voltage ripple at capacitor C. dc This is a signal that compensates for voltage ripple in the capacitor C. In this specification, the compensation signal may also be called a cancellation signal. As described later, the compensation circuit INV1 outputs a compensation signal upon receiving a command from the compensation circuit control device CON1. ​​The signal is output from the compensation circuit INV1 to the capacitor C. dc By supplying a compensation signal to capacitor C, dc This can reduce voltage ripple.

[0019] In the example in Figure 1, the primary side of the compensation circuit INV1 is connected to the DC power supply V dc1 and DC power supply V dc2 Another DC power supply V dc_af It is connected to a DC power supply V dc_af This may also be referred to as the primary DC power supply of the compensation circuit. Thus, in the example of Embodiment 1, the DC power supply connected to the primary side of the compensation circuit INV1 (i.e., DC power supply V dc_af ) is a DC power supply (i.e., DC power supply V) connected to the primary side of the DC / DC converter DCDC1. dc1 This is a different DC power source.

[0020] The secondary side of the compensation circuit INV1 is capacitor C. dc It is connected to the capacitor C. Therefore, between the DC / DC converter DCDC1 and the compensation circuit INV1, there is a capacitor C. dc There is an intervening factor.

[0021] Figure 2 shows an example configuration of the compensation circuit INV1. Figure 2 illustrates a compensation circuit INV1 that includes a single-phase inverter circuit (DC / AC converter). The compensation circuit INV1 in Figure 2 is an example of an active filter. In the example in Figure 2, the compensation circuit INV1 includes a capacitor C af Switching elements S1~S4, reactor L f, Capacitor C f It also has a matching transformer MT.

[0022] Capacitor C af is a DC power supply V dc1 It is connected in parallel with capacitor C. af It is located before the switching elements S1~S4. Capacitor C af This is the smoothing capacitor in the compensation circuit INV1. Capacitor C af This may also be called a smoothing capacitor for a compensation circuit.

[0023] Generally, the rated output of the compensation circuit INV1 is smaller than the rated output of the DC / DC converter DCDC1. Therefore, capacitor C af The capacitance is capacitor C dc It is generally smaller than capacitance.

[0024] Switching elements S1 to S4 are connected to each other to form a bridge circuit. In the example in Figure 2, switching element S1 and switching element S2 are directly connected. In the example in Figure 2, switching element S1 is the upper switching element and switching element S2 is the lower switching element.

[0025] Switching elements S3 to S4 are paired with switching elements S1 to S2, respectively. In the example in Figure 2, switching elements S3 and S4 are directly connected. In the example in Figure 2, switching element S3 is the upper switching element, and switching element S4 is the lower switching element.

[0026] In Embodiment 1, the switching elements S1 to S4 are switched according to a control signal (e.g., a PWM signal described later) supplied from the compensation circuit control device CON1. ​​This switching allows the DC voltage to be converted to the AC voltage.

[0027] Switching elements S1 to S4 can be any type of semiconductor switching element. Examples of semiconductor switching elements include IGBTs (Insulated Gate Bipolar Transistors) and MOSFETs (Metal-Oxide Semiconductor Field Effect Transistors).

[0028] Figure 2 illustrates a two-level inverter circuit for clarity. However, the level of the inverter circuit in compensation circuit INV1 is not limited to this example. Therefore, the level of the inverter circuit in compensation circuit INV1 may be 3 or higher. In other words, compensation circuit INV1 may have multiple inverter circuits.

[0029] Reactor L f and capacitor C f It is located downstream of the switching elements S1 to S4. Reactor L f and capacitor C f These are connected to each other to form an LC filter. Reactor L f This may also be called a filter inductor for a compensation circuit, and capacitor C f This may also be called a filter capacitor for a compensation circuit.

[0030] An LC filter can remove noise from the AC voltage output from the inverter circuit. However, the compensation circuit INV1 does not necessarily have to have an LC filter. For example, if the compensation circuit INV1 has an MMC (Modular Multi-Level) inverter circuit, the compensation circuit INV1 does not need to have an LC filter. In this way, it is also possible to realize a filterless compensation circuit INV1.

[0031] In the example in Figure 2, the matching transformer MT is located after the LC filter. The matching transformer MT is provided for impedance matching between the primary and secondary sides of the compensation circuit INV1. In the example in Figure 2, N1 represents the number of turns of the primary winding of the matching transformer MT, and N2 represents the number of turns of the secondary winding of the matching transformer MT.

[0032] As shown in Figure 3 below, the secondary winding of the matching transformer MT is connected to the capacitor C mentioned above. dc It is connected to the capacitor C. Therefore, the compensation circuit INV1 is configured to generate the above-mentioned compensation signal on the secondary winding of the matching transformer MT. As described above, the inverter circuit in the compensation circuit INV1 is connected to the capacitor C via the matching transformer MT. dc Connected.

[0033] Figure 3 shows a more detailed example of the configuration of the power converter 1 compared to Figure 1. As shown in Figure 3, the power converter 1 includes a capacitor C dc The voltage (hereinafter referred to as V) c_dc It is equipped with a voltage sensor VT1 that detects (represented as ). The type of voltage sensor VT1 is V c_dc It is not particularly limited as long as it can be detected.

[0034] The voltage sensor VT1 is V c_dc The detected value is supplied to the compensation circuit control device CON1. ​​Therefore, for example, the compensation circuit control device CON1, c_dc Based on this, a PWM signal can be generated. Then, the compensation circuit INV1 can generate a compensation signal based on the PWM signal supplied from the compensation circuit control device CON1. ​​In this way, by providing the voltage sensor VT1, the compensation circuit INV1 can output a more appropriate compensation signal.

[0035] Figure 4 shows an example of a control block in the compensation circuit control device CON1. ​​The compensation circuit control device CON1 only needs to be able to control the compensation circuit INV1. The compensation circuit control device CON1 may also be simply called a control device.

[0036] In the example in Figure 4, the control block is V c_dc It is designed to generate a PWM signal by feedback control based on this. The compensation circuit control device CON1 in the example in Figure 4 has an LPF (Low Pass Filter) 411, a divider 412, a constant unit 413, an adder / subtractor 414, a P (Proportional) controller 415, and a PWM signal generation unit 416.

[0037] The LPF411 can be any type of digital filter. In the example in Figure 4, the LPF411 receives voltage from the voltage sensor VT1. c_dc The following is input. The LPF411 passes the low-frequency component of Vc_dc, and V c_dc Frequency filtering is performed to block the high-frequency components. Therefore, according to the LPF411, Vc _dc The DC component can be extracted.

[0038] In this specification, LPF411 is used for V c_dc The signal after filtering is V c_dc_filtered It is written as follows. LPF411 is V c_dc_filtered Outputs V c_dc_filtered V c_dc This corresponds to the DC component of V. c_dc_filtered By generating a PWM signal based on V c_dc By canceling out the ripple, a suitable PWM signal can be obtained. As a result, V c_dc By canceling out the ripple, a suitable compensation signal can be obtained.

[0039] In the example in Figure 4, the divider 412 receives (i) voltage from the voltage sensor VT1. c_dc (ii) When the input is received, V c_dc_filtered The input is V. Divider 412 is V c_dc_filtered V c_dc Divide by .

[0040] Therefore, the divider 412 is, SIG=V c_dc_filtered / V c_dc It outputs a signal SIG, which is represented as V. c_dc_filtered V c_dc It can be said that this is a signal that has been standardized by [the relevant authority].

[0041] The constant unit 413 outputs the constant "1". In the example in Figure 4, the adder / subtractor 414 receives (i) SIG from the divider 412 and (ii) the constant from the constant unit 413. The adder / subtractor 414 divides SIG by the constant.

[0042] Therefore, the adder / subtractor 414 is, ΔSIG = SIG-1 The signal ΔSIG, expressed as ΔSIG, is output. ΔSIG can be said to be the signal from which the steady-state component of SIG has been removed. By dividing SIG by the above constant using the adder / subtractor 414, the oscillation component of SIG (V) is obtained. c_dc It is possible to extract the component corresponding to the ripple.

[0043] The P controller 415 has a predetermined gain K. K should be set to be suitable for generating the PWM signal in the compensation circuit control device CON1. ​​For example, K may be set according to the design specifications of the compensation circuit INV1. In the example of Embodiment 1, K is set as K = N1 / N2. That is, in the example of Embodiment 1, K is set to a value equal to the turns ratio of the matching transformer MT. Thus, K is set according to, for example, the design specifications of the matching transformer MT and V c_dc It may be set accordingly.

[0044] In the example shown in Figure 4, the P controller 415 receives ΔSIG from the adder / subtractor 414. Therefore, the P controller 415, ΔSIG_AMP = K × ΔSIG The output signal ΔSIG_AMP is represented as ΔSIG. ΔSIG_AMP is the signal after ΔSIG has been amplified by gain K.

[0045] The PWM signal generation unit 416 obtains ΔSIG_AMP from the P controller 415. The PWM signal generation unit 416 generates a PWM signal based on ΔSIG_AMP. The PWM signal generation unit 416 may generate a PWM signal based on ΔSIG_AMP using any method (e.g., a known method).

[0046] The PWM signal generation unit 416 supplies the generated PWM signal to the compensation circuit INV1. More specifically, the PWM signal generation unit 416 supplies the PWM signal to the switching elements S1 to S4. The compensation circuit INV1 generates a compensation signal based on the PWM signal. Specifically, the compensation signal is generated when the switching elements S1 to S4 in the compensation circuit INV1 are switched based on the PWM signal. The compensation circuit INV1 supplies the generated compensation signal to the capacitor C dc To supply.

[0047] As described above, the compensation circuit control device CON1 is, for example, V c_dc A PWM signal can be generated by feedback control based on this. By using the control block shown in Figure 4 to generate a PWM signal, V c_dc A suitable compensation signal can be obtained by canceling out the ripple. For example, by generating a compensation signal based on the PWM signal in the example in Figure 4, V c_dc A compensation signal can be obtained as a voltage signal in the opposite phase to the ripple.

[0048] (Verification through simulation) The inventors of this application (hereinafter referred to as "the inventors") conducted simulations to verify the usefulness of the power converter 1. Figure 5 schematically shows the simulation model constructed by the inventors. The simulation model in Figure 5 simulates the main circuit section 10 of the power converter 1.

[0049] In the simulation model in Figure 5, impedance Z is used to simulate ripple. cable It is positioned. Z cableequivalently represents the impedance of the wiring in the DC converter DCDC1. In the example of FIG. 5, Z cable is connected to the DC power supply V dc1 .

[0050] The inventors derived the above-mentioned V c_dc by simulation. In addition, the inventors derived the voltage V in , current I in , and voltage V af shown in FIG. 5 by simulation. I in is the current flowing through Z cable . V in represents the voltage after a voltage drop with respect to V cable occurs due to the I in flowing through Z dc1 . V af represents the voltage of the secondary winding of the matching transformer MT. That is, V af represents the compensation signal that is the output of the compensation circuit INV1.

[0051] FIG. 6 shows an example of the simulation results derived by the inventors. In the graph of FIG. 6, the horizontal axis represents time (t), and the vertical axis represents the signal value. The waveform of V in derived by simulation is shown at reference numeral 610 in FIG. 6. The voltage V in_base in the example of reference numeral 610 represents V in when the compensation signal is not supplied from the compensation circuit INV1. The V in_base in the example of reference numeral 610 corresponds to the comparative example in FIG. 6.

[0052] As shown at reference numeral 610, the ripple of V in is sufficiently smaller than the ripple of V in_base . This verifies that the method of Embodiment 1 can effectively reduce the ripple of V in .

[0053] The waveform of I in derived by simulation is shown at reference numeral 620 in FIG. 6. The current Iin_base This is the case when no compensation signal is supplied from the compensation circuit INV1. in This represents I in the example of symbol 620. in_base This corresponds to the comparative example in Figure 6.

[0054] As shown in reference numeral 620, I in The ripple is I in_base It is sufficiently small compared to the ripple. Thus, by the method of Embodiment 1, I in It can also effectively reduce ripple.

[0055] In Figure 6, reference numeral 630 represents V derived from the simulation. af The waveform is shown. Voltage V in the example of reference numeral 630 c_dc (AC) is V c_dc This represents the AC component of V. c_dc (AC) is V c_dc This corresponds to a ripple. In the example of code 630, V af V c_dc (AC) is a voltage signal with the opposite phase. As can be understood from this, V af capacitor C dc By supplying to capacitor C, dc The voltage ripple in can be at least partially canceled out. Therefore, capacitor C dc Voltage ripple can be effectively reduced in this context.

[0056] Next, the inventors considered V in Figure 6. in , V in_base , I in , and I in_base Each of these was analyzed using the Fast Fourier Transform (FFT). Figure 7 shows the results of the FFT analysis. In the graph in Figure 7, the horizontal axis represents frequency and the vertical axis represents signal value.

[0057] In Figure 7, reference numeral 710 corresponds to V in and V in_base The results of the FFT analysis for each of them are shown. For example, V inThe harmonic components in are V in_base This indicates that it is sufficiently small compared to the harmonic components in . In particular, in the example of symbol 710, V in The second harmonic component in is V in_base It is sufficiently small compared to the second harmonic component in V. The example of reference numeral 710 is also obtained by the method of Embodiment 1. in This confirms that it can effectively reduce ripple.

[0058] In Figure 7, reference numeral 720 indicates I in and I in_base The results of the FFT analysis for each of them are shown. The example of code 720 is I in The harmonic components in are I in_base This indicates that it is sufficiently small compared to the harmonic components in . In particular, in the example of symbol 720, I in The second harmonic component in is I in_base It is sufficiently small compared to the second harmonic component in [the example of reference numeral 720]. The example of reference numeral 720 is also obtained by the method of Embodiment 1, I in This confirms that it can effectively reduce ripple.

[0059] (Further verification through simulation) As mentioned above, Non-Patent Document 1 describes a method for compensating for ripple in the input voltage of a DAB converter using a DC active filter. Therefore, the inventors conducted further simulations to verify the superiority of the method of Embodiment 1 over the method of Non-Patent Document 1.

[0060] Specifically, the inventors derived the voltage and current when employing the method described in Non-Patent Document 1, based on the simulation model in Figure 5. More specifically, the inventors replaced the DC / DC converter in the simulation model in Figure 5 with a DAB converter and then derived the voltage and current when employing the method described in Non-Patent Document 1.

[0061] Figure 8 shows an example of simulation results derived by the inventors. Figure 8 is a counterpart to Figure 6. The example of reference numeral 810 in Figure 8 is a counterpart to the example of reference numeral 610 in Figure 6. Voltage V in the example of reference numeral 810 in_base2 V when adopting the method of Non-Patent Document 1 in This represents V in the example of symbol 810. in_base2 This corresponds to the comparative example in Figure 8.

[0062] As indicated by symbol 810, V in The ripple is V in_base2 It is smaller compared to the ripple. This means that, according to the method of Embodiment 1, V is smaller compared to the method of Non-Patent Document 1. in This confirms that it can effectively reduce ripple.

[0063] The example of reference numeral 820 in Figure 8 is a counterpart to the example of reference numeral 620 in Figure 6. Current I in the example of reference numeral 820 in Figure 8 in_base2 This is the case when the method described in Non-Patent Document 1 is adopted. in This represents I in the example of symbol 820. in_base2 This corresponds to the comparative example in Figure 8.

[0064] As shown in reference numeral 820, I in The ripple is I in_base2 It is smaller compared to the ripple. This means that, according to the method of Embodiment 1, compared to the method of Non-Patent Document 1, in This also supports the fact that it can effectively reduce ripple.

[0065] Next, the inventors considered V in Figure 8. in , V in_base2 , I in , and I in_base2 FFT analysis was performed on each of these. Figure 9 shows the results of the FFT analysis. Figure 9 is a counterpart to Figure 7.

[0066] The example of reference numeral 910 in Figure 9 is a counterpart to the example of reference numeral 710 in Figure 7. Reference numeral 910 has V in and V in_base2The results of the FFT analysis for each of them are shown. For example, V in The harmonic components in are V in_base2 This indicates that it is small compared to the harmonic components in . In particular, in the example of symbol 910, V in The second harmonic component in is V in_base2 It is sufficiently small compared to the second harmonic component in the example of reference numeral 910. According to the method of Embodiment 1, V is smaller compared to the method of Non-Patent Literature 1. in This confirms that it can effectively reduce ripple.

[0067] The example of reference numeral 920 in Figure 9 is a counterpart to the example of reference numeral 720 in Figure 7. Reference numeral 920 is I in and I in_base2 The results of the FFT analysis for each of them are shown. The example of code 920 is I in The harmonic components in are I in_base2 This indicates that it is small compared to the harmonic components in . In particular, in the example of symbol 920, I in The second harmonic component in is I in_base2 It is sufficiently small compared to the second harmonic component in the example of reference numeral 920. In the example of reference numeral 920, according to the method of Embodiment 1, compared to the method of Non-Patent Literature 1, in This confirms that it can effectively reduce ripple.

[0068] (effect) As described above, according to Embodiment 1, voltage ripple in a power converter can be reduced by a method different from the conventional method (e.g., a method different from the method in Non-Patent Document 1). In other words, according to Embodiment 1, voltage ripple emitted by a power converter can be reduced by a method different from the conventional method.

[0069] The DC / DC converter in Non-Patent Document 1 is limited to a DAB converter. On the other hand, the DC / DC converter in Embodiment 1 is not limited to a DAB converter. Therefore, the method of Embodiment 1 is more versatile than the method of Non-Patent Document 1.

[0070] Furthermore, the method described in Non-Patent Document 1 requires that the voltage of the DC active filter itself be fed back in the voltage feedback section of the DC active filter. Therefore, it is conceivable that the method described in Non-Patent Document 1 may not be able to provide proper voltage feedback, and as a result, may not be able to generate an appropriate compensation signal.

[0071] On the other hand, according to the method of Embodiment 1, a compensation signal can be generated without feeding back the voltage of the compensation circuit itself. Therefore, the method of Embodiment 1 has a lower risk of failing to provide proper voltage feedback compared to the method of Non-Patent Document 1. For this reason, the method of Embodiment 1 can reliably generate an appropriate compensation signal compared to the method of Non-Patent Document 1.

[0072] In addition, the method of Embodiment 1 does not require feedback of the compensation circuit's own voltage, thus simplifying the overall configuration of the power converter. Thus, Embodiment 1 allows for the reduction of voltage ripple in the power converter using a simpler method compared to Non-Patent Document 1.

[0073] Furthermore, according to the method of Embodiment 1, the capacitor C dc Voltage ripple in can be effectively reduced. Therefore, in Embodiment 1, a capacitor with high ripple tolerance is used, Capacitor C dc It is not necessary to use it as such. That is, in Embodiment 1, a capacitor having high capacitance is used as capacitor C dc It is not necessary to use it as such. Therefore, in Embodiment 1, a small capacitor is used as capacitor C dc It can be used as such. Therefore, the method of Embodiment 1 also contributes to miniaturization and cost reduction of power conversion devices.

[0074] [Embodiment 2] The configuration of the main circuit in the power converter 1 is not limited to the example of Embodiment 1. Figure 10 shows an example of the configuration of the main circuit in Embodiment 2. In this specification, the main circuit in the example of Figure 10 is referred to as main circuit 10A. In the main circuit 10A in Figure 10, unlike the main circuit 10 in Embodiment 1, the DC power supply V dc_af It is not provided.

[0075] In the main circuit section 10A, capacitor C dc However, capacitor C is used as the DC power supply on the primary side of the compensation circuit INV1. dc However, it is connected to the primary side of the compensation circuit INV1. In this way, capacitor C dc It can also be used in conjunction with the primary DC power supply of the compensation circuit INV1. Capacitor C dc By using the DC power supply in combination with the main circuit section, the DC power supply V dc_af It can be removed.

[0076] According to Embodiment 2, the total number of DC power supplies in the main circuit can be reduced compared to Embodiment 1. Therefore, the configuration of Embodiment 2 is beneficial from the viewpoint of reducing the cost of the power converter.

[0077] In Figure 10, the main circuit section 10A includes capacitor C, which is a smoothing capacitor for the DC / DC converter. dc Next, capacitor C, which is a smoothing capacitor for the compensation circuit. af It is also possible to combine the functions of the above. Therefore, the main circuit section 10A in Figure 10 is a capacitor C af It is not necessarily required to have this feature. Thus, in Embodiment 2, the smoothing capacitor for the DC / DC converter can also be used in combination as a smoothing capacitor for the compensation circuit.

[0078] [Embodiment 3] Figure 11 shows an example of the configuration of the main circuit in Embodiment 3. In this specification, the main circuit in the example in Figure 11 is referred to as the main circuit 10B. In the main circuit 10B in Figure 11, unlike the main circuit 10 in Embodiment 1, the DC power supply V dc_afIt is not provided.

[0079] In the main circuit section 10B, the primary side of the compensation circuit INV1 is connected to the DC power supply V dc1 It is connected to the following. As shown in Figure 11, in the main circuit section 10B, the DC power supply connected to the primary side of the compensation circuit INV1 is a DC power supply common to the DC power supply connected to the primary side of the DC / DC converter DCDC1.

[0080] Thus, the DC power supply on the primary side of the DC / DC converter DCDC1 is V dc1 It can also be used in conjunction with the DC power supply on the primary side of the compensation circuit INV1. That is, by adopting the configuration shown in Figure 11, the DC power supply V can be supplied from the main circuit. dc_af It can be removed.

[0081] Embodiment 3 also reduces the total number of DC power supplies in the main circuit compared to Embodiment 1. Therefore, the configuration of Embodiment 3 is also beneficial from the viewpoint of reducing the cost of the power converter.

[0082] [Examples of implementation using software] The function of the power conversion device 1 (hereinafter referred to as "the device") is a program that causes the device to function as a computer, and can be realized by a program that causes the computer to function as each control block of the device (in particular, the compensation circuit control device CON1).

[0083] In this case, the device includes a computer having at least one control device (e.g., a processor) and at least one storage device (e.g., memory) as hardware for executing the program. By executing the program using this control device and storage device, the functions described in each of the embodiments are realized.

[0084] The above program may be recorded on one or more computer-readable recording media, not temporary ones. These recording media may or may not be provided by the above device. In the latter case, the program may be supplied to the above device via any wired or wireless transmission medium.

[0085] Furthermore, some or all of the functions of each of the above control blocks can also be realized by logic circuits. For example, an integrated circuit in which logic circuits functioning as each of the above control blocks are formed is also included in one aspect of the present invention. In addition, it is also possible to realize the functions of each of the above control blocks by, for example, a quantum computer.

[0086] Each of the processes described in the above embodiments may be performed by AI (Artificial Intelligence). In this case, the AI ​​may operate on the control device described above, or it may operate on other devices (e.g., an edge computer or a cloud server).

[0087] 〔summary〕 A power conversion device according to embodiment 1 of the present invention comprises a DC / DC converter, a smoothing capacitor connected to the DC / DC converter, a compensation circuit connected in series with the smoothing capacitor, a control device for controlling the compensation circuit, and a voltage sensor for detecting the voltage of the smoothing capacitor. The control device controls the compensation circuit based on the voltage detected by the voltage sensor so that the compensation circuit outputs a compensation signal that at least partially cancels out the voltage ripple in the smoothing capacitor.

[0088] In the power conversion device according to embodiment 2 of the present invention, in embodiment 1, the compensation signal may be a voltage signal that is in the opposite phase to the voltage ripple.

[0089] In the power conversion device according to embodiment 3 of the present invention, in embodiment 1 or 2, the control device may generate a PWM (Pulse Width Modulation) signal based on the voltage detected by the voltage sensor, and the compensation circuit may generate the compensation signal based on the PWM signal supplied from the control device.

[0090] In the power conversion device according to embodiment 4 of the present invention, in embodiment 3, the control device may have an LPF (Low Pass Filter), and the control device may generate the PWM signal based on the signal obtained after the voltage detected by the voltage sensor has been filtered by the LPF.

[0091] In the power conversion device according to embodiment 5 of the present invention, in any one of embodiments 1 to 4, the DC power supply connected to the primary side of the compensation circuit may be a different DC power supply from the DC power supply connected to the primary side of the DC / DC converter.

[0092] In the power conversion device according to embodiment 6 of the present invention, in embodiment 5, the smoothing capacitor may be used as a DC power supply connected to the primary side of the compensation circuit.

[0093] In the power conversion device according to embodiment 7 of the present invention, in any one of embodiments 1 to 4, the DC power supply connected to the primary side of the compensation circuit may be a DC power supply common to the DC power supply connected to the primary side of the DC / DC converter.

[0094] [Additional Notes] One aspect of the present invention is not limited to the embodiments described above, and various modifications are possible within the scope of the claims. Embodiments obtained by appropriately combining the technical means disclosed in different embodiments are also included within the technical scope of one aspect of the present invention. [Explanation of Symbols]

[0095] 1. Power converter 10,10A,10B Main circuit section DCDC1 DC / DC Converter INV1 compensation circuit CON1 Compensation Circuit Control Device C dc Capacitor (smoothing capacitor connected to a DC / DC converter) VT1 Voltage Sensor 411 LPF 416 PWM signal generation section V dc1 DC power supply (DC power supply connected to the primary side of a DC / DC converter) V dc_af DC power supply (DC power supply connected to the primary side of the compensation circuit) V af Voltage (example of a compensation signal)

Claims

1. DC / DC converter and A smoothing capacitor connected to the DC / DC converter, A compensation circuit connected in series with the smoothing capacitor, A control device that controls the compensation circuit, The system includes a voltage sensor that detects the voltage of the smoothing capacitor, The control device controls the compensation circuit based on the voltage detected by the voltage sensor, such that the control device causes the compensation circuit to output a compensation signal that at least partially cancels out the voltage ripple in the smoothing capacitor.

2. The power conversion device according to claim 1, wherein the compensation signal is a voltage signal that is in the opposite phase to the voltage ripple.

3. The control device generates a PWM (Pulse Width Modulation) signal based on the voltage detected by the voltage sensor. The power conversion device according to claim 1, wherein the compensation circuit generates the compensation signal based on the PWM signal supplied from the control device.

4. The control device has an LPF (Low Pass Filter), The power conversion device according to claim 3, wherein the control device generates the PWM signal based on the signal obtained after the voltage detected by the voltage sensor has been filtered by the LPF.

5. The power conversion device according to claim 1, wherein the DC power supply connected to the primary side of the compensation circuit is a DC power supply separate from the DC power supply connected to the primary side of the DC / DC converter.

6. The power conversion device according to claim 5, wherein the smoothing capacitor is used as a DC power supply connected to the primary side of the compensation circuit.

7. The power conversion device according to claim 1, wherein the DC power supply connected to the primary side of the compensation circuit is a DC power supply common to the DC power supply connected to the primary side of the DC / DC converter.

Images