Power conversion device

Abstract

To provide a power conversion device that allows arbitrary selection of the number of circuits mounted in a conversion circuit and can suppress a distortion rate of an AC current waveform.SOLUTION: A power conversion device comprises: multiple AC-DC conversion circuits which are connected in parallel between an AC power supply and a DC bus and performs electric power conversion between the AC power supply and the DC bus; multiple AC-DC control units that control the respective AC-DC conversion circuits; and a main control unit that controls the AC-DC control units. The main control unit transmits an AC command value generated in accordance with an AC power of the AC poser supply to each of the AC-DC control units. The AC-DC control units control the respective AC-DC conversion circuits so that the AC current input to each of the AC-DC conversion circuits from the AC power supply assumes a value corresponding to the AC command value.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a power conversion device. [Background technology]

[0002] In order to reduce carbon dioxide emissions on earth, the introduction of solar power generation and electric vehicles is required, and the development of power conversion equipment such as power conditioners for solar power generation and power conversion devices such as chargers for electric vehicles is being promoted. On the other hand, the desired installation scale, such as the rated power of solar power generation and the number of electric vehicles to be charged, varies depending on the installation site of the equipment. Therefore, in order to expand the introduction of solar power generation and electric vehicles, it is effective to develop power conversion equipment that can accommodate a wide range of installation scales and increase the number of sites where it can be installed. Specifically, it is desired to realize a power conversion device that can arbitrarily select the number of AC-DC conversion circuits that convert power between an AC power source and a DC bus, or the number of DC-DC conversion circuits that convert power between a solar cell and a DC bus, or between an electric vehicle or a stationary storage battery and a DC bus. As conventional techniques related to such power conversion devices, for example, those described in Patent Documents 1 and 2 are known.

[0003] Patent Document 1 discloses a power combining / distribution device that is connected to the DC power supply devices and combines and distributes the DC power input from each of the DC power supply devices, a plurality of DC / AC converters connected to the power combining / distribution device, a plurality of DC / DC converters connected to the power combining / distribution device, an AC device connection section that is connected to the DC / AC converter and to which an AC device that supplies and demands AC power is connected on the other side, a DC device connection section that is connected to the DC / DC converter and to which a DC device that supplies and demands DC power is connected on the other side, and a power combining / distribution device that combines and distributes the power between the power combining / distribution device, the DC / AC converter, and the DC / DC converter. and a control device that controls the combination of DC power and the supply and distribution of power to each of the AC device connection units and the DC device connection units by controlling either the AC converter or the DC / DC converter, and when connecting to a power grid to exchange power with the power grid, the control device selects at least one master from the multiple DC / AC converters and stabilizes the DC voltage of the DC bus of the power combining / distribution device by controlling the DC voltage of the master DC / AC converter, and performs active power control on the remaining DC / AC converter and the multiple DC / DC converters.

[0004] Patent Document 2 discloses a power conversion device having a plurality of power converters connected in parallel to solar cells, in which one of the plurality of power converters performs maximum power tracking control of the solar cells as a whole, while the remaining power converters perform current control. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] JP 2020-58161 A [Patent Document 2] JP 2011-141794 A Summary of the Invention [Problem to be solved by the invention]

[0006] The conventional technology described in Patent Document 1 above is a technology related to an electric power supply and demand system that has multiple electric power supply and demand facilities and aims to realize flexible supply and receipt of electric power, in which a master selected from multiple power converters controls DC and AC voltages. However, if one master tries to control multiple electric power supply and demand facilities, voltage fluctuations become large when the load fluctuates. Patent Document 1 shows that multiple masters are selected to suppress such voltage fluctuations, but does not show a method for balancing the currents of each power converter, which is necessary to control a common voltage among multiple power converters.

[0007] In addition, the prior art described in Patent Document 2 discloses a power converter in which multiple power converters are connected in parallel to configure a larger power converter, and shows a method of sending current command values ​​to the multiple parallel-connected power converters and having each power converter control its current to balance the current of each power converter. However, even if this method is applied, if the number of AC-DC conversion circuits and DC-DC conversion circuits connected to the DC bus increases, the time required to calculate the current command value of each conversion circuit becomes longer, and the update time interval of the current command value sent to each conversion circuit becomes longer. This makes it difficult to suppress the distortion rate of the AC current waveform that changes from moment to moment in the AC-DC conversion circuit.

[0008] The present invention has been made in view of the above, and has an object to provide a power conversion device in which the number of conversion circuits mounted can be selected arbitrarily and the distortion rate of the AC current waveform can be suppressed. [Means for solving the problem]

[0009] The present application includes multiple means for solving the above-mentioned problems. One example is a power conversion device including a plurality of AC-DC conversion circuits connected in parallel between an AC power source and a DC bus and performing power conversion between the AC power source and the DC bus, a plurality of AC-DC control units each controlling the plurality of AC-DC conversion circuits, and a main control unit controlling the plurality of AC-DC control units, wherein the main control unit transmits an AC command value generated according to the AC power of the AC power source to each of the plurality of AC-DC control units, and the plurality of AC-DC control units each control the plurality of AC-DC conversion circuits so that the AC current input from the AC power source to each of the plurality of AC-DC conversion circuits has a value according to the AC command value. Effect of the Invention

[0010] According to the present invention, the number of conversion circuits to be mounted can be selected arbitrarily, and the distortion rate of the AC current waveform can be suppressed. [Brief description of the drawings]

[0011] [Figure 1] 1 is a diagram showing a power conversion device according to a first embodiment together with related configuration. [Diagram 2] 1A and 1B are diagrams for explaining the calculation principle of an instantaneous phase. [Diagram 3] 4A to 4C are diagrams illustrating the principle of processing in an AC current control unit when the amplitude and phase of an AC current are received as an AC command value. [Figure 4] 4A to 4C are diagrams illustrating the principle of processing in an AC current control unit when the amplitude and phase of an AC current are received as an AC command value. [Diagram 5] FIG. 11 is a diagram showing a power conversion device according to a second embodiment together with related configuration. [Figure 6] FIG. 13 is a diagram showing a power conversion device according to a third embodiment together with related configuration. [Figure 7] FIG. 13 is a diagram showing a power conversion device according to a fourth embodiment together with related configuration. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0012] Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

[0013] <First embodiment> A first embodiment of the present invention will be described with reference to FIGS.

[0014] FIG. 1 is a diagram showing a power conversion device according to the present embodiment together with related configuration.

[0015] In FIG. 1, the power conversion device 1 is connected to an AC power source 3, a solar cell 4 (PV: Photovoltaic), a storage battery 5, and a load 6, and can output the power generated by the solar cell 4 to the AC power source 3, charge the power input from the solar cell 4 or the AC power source 3 to the storage battery 5, supply power to the load 6, and supply power from the storage battery 5 to the load 6. The solar cell 4 functions as a DC power source when generating power, and similarly, the storage battery 5 functions as a DC power source when discharging. As the storage battery 5, for example, a battery mounted on an electric vehicle such as an electric car, or a stationary battery (stationary storage battery) is connected. As the load 6, for example, a server to which DC power is to be distributed is connected. As the DC power source connected to the power conversion device 1, in addition to the solar cell 4 and the storage battery 5, for example, a fuel cell is conceivable.

[0016] The power conversion device 1 includes a plurality of AC-DC conversion circuits 21, 22, 23 connected in parallel to perform power conversion between an AC power source 3 and a DC bus 2, a DC-DC conversion circuit 24 that performs power conversion between a solar cell 4, which is a DC power source, and the DC bus 2, a DC-DC conversion circuit 25 that performs power conversion between a storage battery 5, which is a DC power source, and the DC bus 2, AC-DC control units 11, 12, 13 that control the AC-DC conversion circuits 21, 22, 23, DC-DC control units 14, 15 that control the DC-DC conversion circuits 24, 25, and a main control unit 10 that communicates with the AC-DC control units 11, 12, 13 and the DC-DC control units 14, 15.

[0017] The main control unit 10 includes a system control unit 31, a DC bus voltage control unit 32, and a power distribution unit 33.

[0018] The system control unit 31 detects the voltage and current of the AC power source 3, calculates the effective voltage value, phase, frequency, etc. of the AC power source 3, and detects system abnormalities such as power outages, voltage rise / drop, and frequency rise / drop. Information on the phase and frequency of the AC power source 3 calculated by the system control unit 31 is transmitted to the AC-DC control units 11, 12, and 13 as a signal 60. When the values ​​of power and current input and output to and from the AC power source 3 must be controlled due to constraints on system control, an AC power source target value, which is a target value thereof, is transmitted to the power distribution unit 33 as a signal 35. This AC power source target value is expressed as the phase and amplitude of the current of the AC power source, or the active current and reactive current of the AC power source, or the active power and reactive power of the AC power source.

[0019] The DC bus voltage control unit 32 detects the voltage of the DC bus 2, and generates a DC bus power command value, which is the power to be input to the DC bus 2 required to control the voltage to a target value. Specifically, if the detected voltage of the DC bus 2 is lower than the target value, the DC bus power command value is increased, and if the detected voltage of the DC bus 2 is higher than the target value, feedback control is performed to decrease the DC bus power command value. The DC bus power command value generated by the DC bus voltage control unit 32 is transmitted to the power distribution unit 33 as a signal 34. Note that the above-mentioned DC bus power command value may be a current to be input to the DC bus 2.

[0020] The power distribution unit 33 uses the AC power supply target value (signal 35) received from the system control unit 31, the DC bus power command value (signal 34) received from the DC bus voltage control unit 32, the power target values ​​of the AC power supply 3, solar cell 4, and storage battery 5 received or generated from outside as signal 36, and the voltages of the solar cell 4 and storage battery 5 received from the DC-DC control units 14, 15 to generate AC command values ​​to be transmitted as signals 51, 52, and 53 to the AC-DC control units 11, 12, and 13, and DC command values ​​to be transmitted as signals 54 and 55 to the DC-DC control units 14, 15. Specifically, the power of each of the AC power source 3, the solar cell 4, and the storage battery 5 is set within the power range of the AC power source 3, the solar cell 4, and the storage battery 5, which is constrained by the AC power source target value (signal 35), the power target value (signal 36), and the voltages of the solar cell 4 and the storage battery 5, and the total power input from the AC power source 3, the solar cell 4, and the storage battery 5 is set to be equal to the DC bus power command value (signal 34).

[0021] As described above, the power distribution unit 33 distributes the DC bus power command value to the power input from each of the AC-DC conversion circuits 21, 22, 23 and the DC-DC conversion circuits 24, 25 to the DC bus 2. As a result, the main control unit 10 changes the AC command values ​​(signals 51, 52, 53) and the DC command values ​​(signals 54, 55) to control the voltage of the DC bus 2. Here, the AC command values ​​(signals 51, 52, 53) are expressed as the phase and amplitude of the AC current of the AC-DC conversion circuits 21, 22, 23, or the active current and reactive current, or the active power and reactive power. Moreover, the DC command values ​​(signals 54, 55) are expressed as the DC power or the DC current of the DC-DC conversion circuits 24, 25.

[0022] The AC-DC control units 11, 12, 13 each include an instantaneous phase calculation unit 46, 47, 48 and each of the AC current control units 41, 42, 43. The instantaneous phase calculation units 46, 47, 48 calculate an instantaneous phase using information (signal 60) on the phase and frequency of the AC current of the AC power source 3 received from the system control unit 31 of the main control unit 10, and transmit the calculated instantaneous phase to the AC current control units 41, 42, 43 as signals 61, 62, 63.

[0023] Fig. 2 is a diagram for explaining the calculation principle of the instantaneous phase, in which the horizontal axis indicates time and the vertical axis indicates the instantaneous phase to be obtained.

[0024] As shown in FIG. 2, at time t1, when the phase θ1 and frequency f1 of the AC current of the AC power source 3 are received, the instantaneous phase θ is set to the phase θ1, and until time t2 when the phase and frequency of the AC current of the AC power source 3 are received, the instantaneous phase θ is calculated by using the frequency f1 received at time t1. Specifically, the instantaneous phase θ is calculated by adding the phase change amount calculated by integrating the frequency f1 over time t and multiplying it by 2π to the phase θ1. After that, at time t2, when the phase θ2 and frequency f2 of the AC current of the AC power source 3 are newly received, the instantaneous phase θ is set to the phase θ2, and the instantaneous phase θ is calculated using the frequency f2 received at time t2. After that, the instantaneous phase θ is calculated in the same manner, and if the instantaneous phase θ exceeds 2π, 2π is subtracted.

[0025] By the processing of the instantaneous phase calculation units 46, 47, 48 described above, the AC-DC control units 11, 12, 13 can relatively accurately calculate and grasp the instantaneous phase of the AC current of the AC power supply 3 even if the time interval at which the phase θ1 of the AC current of the AC power supply 3 is received from the main control unit 10 is long.

[0026] The AC current control units 41, 42, 43 use the instantaneous phases (signals 61, 62, 63) calculated by the instantaneous phase calculation units 46, 47, 48 to control the AC-DC conversion circuits 21-23 so that the detected AC power or current of the AC-DC conversion circuits 21, 22, 23 becomes the AC command value (signals 51, 52, 53) received from the main control unit 10.

[0027] 3 and 4 are diagrams for explaining the principle of processing in the AC control unit when the amplitude and phase of the AC current are received as the AC command value.

[0028] 3, the horizontal axis represents the sum of the instantaneous phase θ (signals 61, 62, 63) of the AC power supply calculated by the instantaneous phase calculation units 46, 47, 48 and the phase φ of the AC current of the received AC command value (signals 51, 52, 53). The vertical axis represents the AC current I to be passed through the AC-DC conversion circuits 21, 22, 23, and the current value Ia represents the amplitude of the AC current of the received AC command value (signals 51, 52, 53).

[0029] 3, since the instantaneous phase θ is known, the instantaneous value of the current I to be flowed can be determined from information on the phase φ and the amplitude Ia. AC current control units 41, 42, and 43 control the AC currents of the AC-DC conversion circuits 21, 22, and 23 to the above-mentioned current to be flowed.

[0030] In FIG. 4, the horizontal axis represents time t, and the vertical axis represents the waveforms of the voltage V of the AC power supply 3 and the AC current I of the AC-DC conversion circuits 21, 22, and .

[0031] 4, the AC current I of the AC-DC conversion circuits 21, 22, 23 leads the phase φ of the AC current of the AC command value (signals 51, 52, 53) with respect to the phase θ of the AC power source 3, and has an amplitude of the amplitude Ia of the AC current of the AC command value (signals 51, 52, 53). Note that the AC current control units 41, 42, 43 detect the voltage of the DC bus 2, and have a function of correcting the AC power or current of the AC-DC conversion circuits 21, 22, 23 to return the voltage to the original value when the voltage deviates from a preset value.

[0032] As described above, by controlling the AC power or current of the AC-DC conversion circuits 21, 22, 23, it is possible to generate a relatively accurate AC waveform even if the update time interval of the AC command value (signals 51, 52, 53) received from the main control unit 10 is long, and the distortion rate of the current waveform flowing through the AC power supply 3 can be kept low.

[0033] Incidentally, by including frequency components that are integer multiples of the fundamental frequency of the AC power source 3 in addition to the fundamental frequency of the AC power source 3 in the AC command values ​​(signals 51, 52, 53), it is possible to further reduce the distortion rate of the waveform of the current flowing through the AC power source 3. For example, by including third harmonic components and fifth harmonic components in the AC command values ​​(signals 51, 52, 53), it is possible to reduce the third harmonic current and fifth harmonic current flowing through the AC power source 3.

[0034] The DC-DC control units 14 and 15 include DC voltage and current control units 44 and 45. The DC voltage and current control units 44 and 45 control the DC-DC conversion circuits 24 and 25 so that the detected DC power or current of the DC-DC conversion circuits 24 and 25 becomes the DC command value (signal 54 and 55) received from the main control unit 10. Similarly to the AC current control units 41, 42 and 43, the DC-DC control units 14 and 15 detect the voltage of the DC bus 2, and have a function of correcting the DC power or current of the DC-DC conversion circuits 24 and 25 to return the voltage to the original value when the voltage deviates from a preset value. The DC-DC control units 14 and 15 also transmit the detected voltages of the solar cell 4 and the storage battery 5 to the main control unit 10.

[0035] The effects of the present embodiment configured as above will be described.

[0036] The conventional technology described in Patent Document 1 above is a technology related to an electric power supply and demand system that has multiple electric power supply and demand facilities and aims to realize flexible supply and receipt of electric power, in which a master selected from multiple power converters controls DC and AC voltages. However, if one master tries to control multiple electric power supply and demand facilities, voltage fluctuations become large when the load fluctuates. Patent Document 1 shows that multiple masters are selected to suppress such voltage fluctuations, but does not show a method for balancing the currents of each power converter, which is necessary to control a common voltage among multiple power converters.

[0037] In addition, the prior art described in Patent Document 2 discloses a power converter in which multiple power converters are connected in parallel to configure a larger power converter, and shows a method of sending current command values ​​to the multiple parallel-connected power converters and having each power converter control its current to balance the current of each power converter. However, even if this method is applied, if the number of AC-DC conversion circuits and DC-DC conversion circuits connected to the DC bus increases, the time required to calculate the current command value of each conversion circuit becomes longer, and the update time interval of the current command value sent to each conversion circuit becomes longer. This makes it difficult to suppress the distortion rate of the AC current waveform that changes from moment to moment in the AC-DC conversion circuit.

[0038] In contrast, in the present embodiment, a power conversion device 1 includes a plurality of AC-DC conversion circuits 21, 22, and 23 that are connected in parallel between an AC power source 3 and a DC bus 2 and perform power conversion between the AC power source 3 and the DC bus 2, a plurality of AC-DC control units 11, 12, and 13 that control the plurality of AC-DC conversion circuits 21, 22, and 23, respectively, and a main control unit 10 that controls the plurality of AC-DC control units 11, 12, and 13. The main control unit 10 outputs an AC command generated in response to the AC power of the AC power source 3. The AC command values ​​(signals 51, 52, 53) are transmitted to the multiple AC-DC control units 11, 12, 13, respectively, and the multiple AC-DC control units 11, 12, 13 are configured to control the multiple AC-DC conversion circuits 21, 22, 23, respectively, so that the AC current input from the AC power source 3 to the multiple AC-DC conversion circuits 21, 22, 23, respectively, becomes a value corresponding to the AC command value (signals 51, 52, 53).As a result, the number of conversion circuits to be installed can be selected arbitrarily, and the distortion rate of the AC current waveform can be suppressed.

[0039] That is, it is possible to configure power conversion devices with various rated powers by changing the number of AC-DC conversion circuits and DC-DC conversion circuits installed. Also, it is possible to realize a power conversion device that keeps the distortion rate of the AC current waveform low even if the number of conversion circuits installed increases and the update time interval of the current command value of each conversion circuit becomes longer.

[0040] In this embodiment, the number of DC-DC conversion circuits mounted has been described as two, but the number of DC-DC conversion circuits mounted may be increased and some or all of them may be connected in parallel. For example, ten DC-DC conversion circuits may be mounted, two of which are connected in parallel and connected to a solar cell, three others are connected in parallel and connected to a stationary battery, two others are connected in parallel and connected to an electric vehicle, two others are each connected to a different solar cell, and the remaining one is connected to another electric vehicle.

[0041] <Second embodiment> A second embodiment of the present invention will be described with reference to FIG.

[0042] In this embodiment, the main control unit communicates with other AC-DC control units or DC-DC control units via a specific AC-DC control unit or DC-DC control unit. Note that in this embodiment, the same members and functions as those in the first embodiment are given the same reference numerals, and the description will be omitted as appropriate.

[0043] FIG. 5 is a diagram showing the power conversion device according to this embodiment together with related configuration.

[0044] In FIG. 5, the power conversion device 100 is connected to an AC power source 3, a solar cell 4 (PV: Photovoltaic), a storage battery 5, and a load 6, and can output the power generated by the solar cell 4 to the AC power source 3, charge the power input from the solar cell 4 or the AC power source 3 to the storage battery 5, supply power to the load 6, and supply power from the storage battery 5 to the load 6. The solar cell 4 functions as a DC power source when generating power, and similarly, the storage battery 5 functions as a DC power source when discharging. As the storage battery 5, for example, a battery mounted on an electric vehicle such as an electric car, or a stationary battery (stationary storage battery) is connected. As the load 6, for example, a server to which DC power is to be distributed is connected. In addition to the solar cell 4 and the storage battery 5, for example, a fuel cell can be considered as a DC power source connected to the power conversion device 1.

[0045] The power conversion device 100 includes a plurality of AC-DC conversion circuits 121, 122, 123 connected in parallel to perform power conversion between an AC power source 3 and a DC bus 120, a DC-DC conversion circuit 124 to perform power conversion between a solar cell 4, which is a DC power source, and the DC bus 120, a DC-DC conversion circuit 125 to perform power conversion between a storage battery 5, which is a DC power source, and the DC bus 120, AC-DC control units 111, 112, 113 to control the AC-DC conversion circuits 121, 122, 123, DC-DC control units 114, 115 to control the DC-DC conversion circuits 124, 125, and a main control unit 110 to communicate with the AC-DC control units 111, 112, 113 and the DC-DC control units 114, 115.

[0046] Here, the AC-DC control units 111, 112, and 113 and the AC-DC conversion circuits 121, 122, and 123 respectively constitute converter units 101, 102, and 103. Similarly, the DC-DC control units 114 and 115 and the DC-DC conversion circuits 124 and 125 respectively constitute converter units 104 and 105.

[0047] When the main control unit 110 communicates with the AC-DC control units 112 and 113 and the DC-DC control unit 114 (specifically, when transmitting signals 52, 53, 54, 60, etc.), the communication is performed via the AC-DC control unit 111 or the DC-DC control unit 115. For example, when the main control unit 110 communicates with the AC-DC control unit 113, the communication is performed via communication between the main control unit 110 and the AC-DC control unit 111 (signal 130), communication between the AC-DC control unit 111 and the AC-DC control unit 112 (signal 131), and communication between the AC-DC control unit 112 and the AC-DC control unit 113 (signal 132), or via communication between the main control unit 110 and the DC-DC control unit 115 (signal 140), communication between the DC-DC control unit 115 and the DC-DC control unit 114 (signal 141), and communication between the DC-DC control unit 114 and the AC-DC control unit 113 (signal 150). The order in which the main control unit 110 communicates with each unit is not limited to the above, and various combinations are possible.

[0048] The other configurations are similar to those of the first embodiment.

[0049] The present embodiment configured as above can also provide the same effects as the first embodiment.

[0050] Also, the number of communication ports required for the main control unit 110 can be reduced while allowing a larger number of converter units to be connected.

[0051] <Third embodiment> A third embodiment of the present invention will be described with reference to FIG.

[0052] In this embodiment, each of the converter units includes a main control unit, and a specific main control unit functions as a master. Note that in this embodiment, the same members and functions as those in the first and second embodiments are denoted by the same reference numerals, and descriptions thereof will be omitted as appropriate.

[0053] FIG. 6 is a diagram showing the power conversion device according to this embodiment together with the related configuration.

[0054] In FIG. 6, the power conversion device 200 is connected to an AC power source 3, a solar cell 4 (PV: Photovoltaic), a storage battery 5, and a load 6, and can output the power generated by the solar cell 4 to the AC power source 3, charge the power input from the solar cell 4 or the AC power source 3 to the storage battery 5, supply power to the load 6, and supply power from the storage battery 5 to the load 6. The solar cell 4 functions as a DC power source when generating power, and similarly, the storage battery 5 functions as a DC power source when discharging. As the storage battery 5, for example, a battery mounted on an electric vehicle such as an electric car, a stationary battery (stationary storage battery), or the like is connected. As the load 6, for example, a server to which DC power is to be distributed is connected. As the DC power source connected to the power conversion device 1, in addition to the solar cell 4 and the storage battery 5, for example, a fuel cell or the like can be considered.

[0055] The power conversion device 200 includes a plurality of AC-DC conversion circuits 221, 222, 223 connected in parallel to perform power conversion between an AC power source 3 and a DC bus 120, a DC-DC conversion circuit 224 to perform power conversion between a solar cell 4 which is a DC power source and the DC bus 220, a DC-DC conversion circuit 225 to perform power conversion between a storage battery 5 which is a DC power source and the DC bus 220, AC-DC control units 211, 212, 213 which control the AC-DC conversion circuits 221, 222, 223, DC-DC control units 214, 215 which control the DC-DC conversion circuits 224, 225, and main control units 231, 232, 233, 234, 235 which control the AC-DC control units 211, 212, 213 and the DC-DC control units 214, 215, respectively.

[0056] Here, the AC-DC control units 211, 212, 213, the AC-DC conversion circuits 221, 222, 223, and the main control units 231, 232, 233 respectively constitute converter units 201, 202, 203. Similarly, the DC-DC control units 214, 215, the DC-DC conversion circuits 224, 225, and the main control units 234, 235 respectively constitute converter units 204, 205.

[0057] In the power conversion device 200, one of the main control units 231, 232, 233, 234, and 235 serves as a master, and the main control unit serving as the master functions as a main control unit for the entire power conversion device 200, while the remaining main control units function as communication devices. When the main control unit serving as the master communicates with the AC-DC control units or DC-DC control units of other converter units, the communication is performed via the main control units of the other AC-DC control units or DC-DC control units connected in series for communication. For example, when the main control unit 231 acts as a master and communicates with the AC-DC control unit 213, communication is via communication between the main control unit 231 and the main control unit 232 of the converter unit 202 (signal 241), and communication between the main control unit 232 and the main control unit 233 of the converter unit 203 (signal 242), or via communication between the main control unit 231 and the main control unit 235 of the converter unit 205 (signal 245), communication between the main control unit 235 and the main control unit 234 of the converter unit 204 (signal 244), and communication between the main control unit 234 and the main control unit 233 of the converter unit 203 (signal 243).

[0058] The other configurations are similar to those of the first and second embodiments.

[0059] The present embodiment configured as above can also provide the same effects as the first and second embodiments.

[0060] Also, it is unnecessary to provide a housing for the main control unit separately from the converter unit.

[0061] In this embodiment, a configuration has been exemplified in which all of the converter units 201, 202, 203, 204, and 205 are equipped with a main control unit, but it is not necessarily necessary for all of the converter units 201, 202, 203, 204, and 205 to be equipped with a main control unit. For example, only the converter units 201, 202, and 203 equipped with AC-DC conversion circuits 221, 222, and 223 may be configured to be equipped with a main control unit.

[0062] <Fourth embodiment> A fourth embodiment of the present invention will be described with reference to FIG.

[0063] In this embodiment, devices that are the targets of AC power distribution are connected as loads. In this embodiment, the same members and functions as those in the first embodiment are denoted by the same reference numerals, and the description thereof will be omitted as appropriate.

[0064] FIG. 7 is a diagram showing the power conversion device according to this embodiment together with the related configuration.

[0065] In Figure 7, the power conversion device 301 includes a plurality of AC-DC conversion circuits 21, 22, 23, a DC-DC conversion circuit 24, a DC-AC conversion circuit 325, AC-DC control units 11, 12, 13 that control the AC-DC conversion circuits 21, 22, 23, a DC-DC control unit 14 that controls the DC-DC conversion circuit 24, a DC-AC control unit 315 that controls the DC-AC conversion circuit 325, and a main control unit 10 that communicates with the AC-DC control units 11, 12, 13, the DC-DC control unit 14, and the DC-AC control unit 315.

[0066] The DC-AC conversion circuit 325 converts power between the DC bus 2 and the load 306 that is the target of AC power distribution. The DC-AC control unit 315 includes an AC voltage current control unit 345. The AC voltage current control unit 345 detects the AC voltage supplied from the DC-AC conversion circuit 325 to the load 306, and controls the DC-AC conversion circuit 325 so that this AC voltage becomes the AC voltage command value (signal 355) received from the main control unit 10.

[0067] The other configurations are similar to those of the first embodiment.

[0068] The present embodiment configured as above can also provide the same effects as the first embodiment.

[0069] <Additional Notes> The present invention is not limited to the above-described embodiments, and includes various modifications and combinations within the scope of the gist of the present invention. The present invention is not limited to those having all the configurations described in the above-described embodiments, and includes those in which some of the configurations are deleted. The above-described configurations, functions, etc. may be realized by designing some or all of them as an integrated circuit, for example. The above-described configurations, functions, etc. may be realized by software, in which a processor interprets and executes a program that realizes each function. [Explanation of symbols]

[0070] 1...power conversion device, 2...DC bus, 3...AC power source, 4...solar cell, 5...storage battery, 6...load, 10...main control unit, 11,12,13...AC-DC control unit, 14,15...DC-DC control unit, 21,22,23...AC-DC conversion circuit, 24,25...DC-DC conversion circuit, 31...system control unit, 32...DC bus voltage control unit, 33...power distribution unit, 41,42,43...AC current control unit, 44,45...DC voltage and current control unit, 46,47,48...instantaneous phase calculation unit, 100...power conversion device, 101,102,103,104,105...converter unit, 110...main control unit, 111,112,113...AC-DC control unit, 114 , 115...DC-DC control unit, 120...DC bus, 121, 122, 123...AC-DC conversion circuit, 124, 125...DC-DC conversion circuit, 200...power conversion device, 201, 202, 203, 204, 205...converter unit, 211, 212, 213...AC-DC control unit, 214, 215...DC-DC control unit, 220...DC bus, 221, 222, 223...AC-DC conversion circuit, 224, 225...DC-DC conversion circuit, 231, 232, 233, 234, 235...main control unit, 301...power conversion device, 306...load, 315...DC-AC control unit, 325...DC-AC conversion circuit, 345...AC voltage and current control unit

Claims

1. a plurality of AC-DC conversion circuits connected in parallel between an AC power source and a DC bus, the plurality of AC-DC conversion circuits performing power conversion between the AC power source and the DC bus; A plurality of AC-DC control units each controlling the plurality of AC-DC conversion circuits; A power conversion device comprising a main control unit that controls the plurality of AC-DC control units, the main control unit transmits, to each of the plurality of AC-DC control units, an AC command value generated in accordance with the AC power of the AC power supply; The power conversion device is characterized in that the multiple AC-DC control units control the multiple AC-DC conversion circuits respectively so that the AC currents input from the AC power source to the multiple AC-DC conversion circuits respectively have values ​​corresponding to the AC command value.

2. 2. The power conversion device according to claim 1, the main control unit transmits, as the AC command value, a command value indicating an amplitude and a phase of an AC current to each of the plurality of AC-DC control units; The power conversion device is characterized in that the multiple AC-DC control units control the multiple AC-DC conversion circuits respectively so that the amplitude and phase of the AC current input from the AC power source to each of the multiple AC-DC conversion circuits become values ​​corresponding to the AC command value.

3. 2. The power conversion device according to claim 1, the main control unit transmits, as the AC command value, a command value indicating an active current and a reactive current of an AC current to each of the plurality of AC-DC control units; The power conversion device is characterized in that the multiple AC-DC control units control the multiple AC-DC conversion circuits respectively so that the active current and reactive current of the AC current input from the AC power source to each of the multiple AC-DC conversion circuits become values ​​corresponding to the AC command value.

4. 2. The power conversion device according to claim 1, the main control unit transmits, as the AC command value, a command value indicating an active power and a reactive power of an AC current to each of the plurality of AC-DC control units; The power conversion device is characterized in that the multiple AC-DC control units control the multiple AC-DC conversion circuits respectively so that the active power and reactive power of the AC current input from the AC power source to each of the multiple AC-DC conversion circuits become values ​​corresponding to the AC command value.

5. 2. The power conversion device according to claim 1, The power conversion device, wherein the AC command value transmitted from the main control unit to each of the plurality of AC-DC control units includes a fundamental wave component of an AC current and a frequency component that is an integer multiple of the fundamental wave frequency.

6. 2. The power conversion device according to claim 1, The power conversion device according to claim 1, wherein the main control unit changes the AC command value to control the voltage of the DC bus.

7. 2. The power conversion device according to claim 1, The main control unit transmits the phase and frequency of the AC power supply to each of the plurality of AC-DC control units, The power conversion device is characterized in that the multiple AC-DC control units calculate an instantaneous phase of the AC power supply from the phase and frequency of the AC power supply, and use the calculated instantaneous phase to control each of the multiple AC-DC conversion circuits so that the AC currents input from the AC power supplies to each of the multiple AC-DC conversion circuits have values ​​corresponding to the AC command value.

8. 2. The power conversion device according to claim 1, a plurality of DC-DC conversion circuits respectively connected between a plurality of DC power sources and the DC bus, and performing power conversion between the plurality of DC power sources and the DC bus; a plurality of DC-DC control units each controlling the plurality of DC-DC conversion circuits, The main control unit transmits a DC command value to the plurality of DC-DC control units, The power conversion device is characterized in that the multiple DC-DC control units control the DC-DC conversion circuits so that the DC currents input from the multiple DC power sources to the multiple DC-DC conversion circuits respectively have values ​​corresponding to the DC command values.

9. 9. The power conversion device according to claim 8, The power conversion device according to claim 1, wherein the main control unit controls a voltage of the DC bus by changing the AC command value and the DC command value.

10. 9. The power conversion device according to claim 8, the main control unit transmits a command value indicating a power of a direct current as the direct current command value to each of the DC-DC control units; The power conversion device is characterized in that the multiple DC-DC control units control the multiple DC-DC conversion circuits respectively so that the power of the direct current input from the multiple DC power sources to the multiple DC-DC conversion circuits respectively becomes a value corresponding to the DC command value.

11. 2. The power conversion device according to claim 1, A power conversion device having a function of supplying power from the DC bus to a load.

12. 9. The power conversion device according to claim 8, The main control unit is receiving or generating power target values ​​for the AC power source and the DC power source; generating a DC bus current command value required to control the voltage of the DC bus; a power conversion device that generates the AC command value and the DC command value by allocating the DC bus current command value so that the power of the AC power source and the DC power source becomes a value corresponding to the power target value.

13. 9. The power conversion device according to claim 8, The main control unit is receiving or generating power target values ​​for the AC power source and the DC power source; generating a DC bus power command value required to control the voltage of the DC bus; A power conversion device characterized in that the DC bus power command value is allocated so that the power of the AC power source and the DC power source becomes a value corresponding to the power target value, thereby generating the AC command value and the DC command value.

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