Power conversion system

Abstract

A power conversion system comprises: a first power conversion device 1; a current measurement device that is connected between the first power conversion device 1 and a load 10 and that can detect the current in current rating corresponding to the load 10; a filter circuit having at least a reactor and a capacitor; and a control device 20 that controls the first power conversion device 1. The first power conversion device 1 and the control device 20 are housed in a first board A1, and the current measurement device and the filter circuit are housed in a second board A2. In the power conversion system, minimizing the scope of impact when changing the current rating makes it possible to reduce design and evaluation costs, thereby realizing a lower-cost device and facilitating current-rating changes.

Description

Power Conversion Systems

[0001] The present invention relates to a power conversion system made up of a plurality of panels, and more particularly to a power conversion system having a power conversion device and a filter circuit.

[0002] Patent Document 1 discloses a prior art technique for separating a filter circuit from a panel for a power conversion device. The patent document 1 discloses a configuration having a filter circuit and a branch panel that can switch which filter circuit and which motor to drive, with the aim of reducing the driving capacity of the startup inverter.

[0003] The configuration shown in FIG. 1 can be considered as a power conversion system that switches between and operates a plurality of current measuring devices. In FIG. 1, the first and second power conversion devices 1 and 2 have filter circuits (LCL filters) on the output side, and have current measuring devices HCT_A11, HCT_A21, HCT_A31, HCT_B11, HCT_B21, HCT_B31, HCT_A12, HCT_A22, HCT_A32, HCT_B12, HCT_B22, and HCT_B32 dedicated to each current rating and switches MC_A11, MC_A21, MC_A31, MC_B11, MC_B21, MC_B31, MC_C11, MC_A12, MC_A22, MC_A32, MC_B12, MC_B22, MC_B32, and MC_C12 before and after the capacitors C11 and C12.

[0004] Here, when the load (e.g., test load) 10 is large (for a maximum voltage of about 1 kV, it can range from less than 10 A to about 1 kA), it is necessary to use a large conductor rod to support it while ensuring insulation in order to reduce heat generation in the current path. Therefore, mounting it on a panel is preferable. In addition, since there are components such as power conversion devices, current measurement devices, and switches (switching devices) with the same rating that also increase in size, it is also preferable to mount these on a panel.

[0005] JP 2017-11873 A

[0006] The prior art and a simple combination of the prior art and the circuit of FIG. 1 have the following problems.

[0007] The first and second power conversion devices 1 and 2, which are composed of semiconductor components, and the filter circuit and branch panel are on separate panels, but there is no description of the technical significance of this. Furthermore, this is particularly intended for motor drive, and its purpose is to switch the path of drive power, etc., due to differences in required ratings and load power factors, etc., between startup and normal rotation.

[0008] In particular, when applied to charge / discharge devices (which perform power conversion, charge / discharge while measuring current (power) that requires high accuracy for loads with a wide range of test voltage / current requirements, and test characteristics), the following issues arise:

[0009] The charging / discharging device shown in Figure 1 is divided into two parts: (1) a current measuring device whose corresponding current rating range is narrow due to the device's purpose (detection accuracy), a filter circuit that affects its characteristics, and a switch required for switching the current measuring device; and (2) a power conversion device whose corresponding current rating range is relatively wide and can be shared, and whose rating is further classified according to the input voltage. For example, the current measuring device must be rated at 10 A, 100 A, 1 kA, etc. For example, if the power conversion device has a rated current of 1 kA, it can handle a range from less than 10 A to about 1 kA.

[0010] Furthermore, power conversion systems require advance preparations such as verification of thermal characteristics on a panel-by-panel basis. Because the selection criteria differ between the part with the current measuring device and the other main circuit parts, if the system is integrated into a single panel, advance preparations for many combinations become necessary.

[0011] In particular, charging and discharging devices are used as test equipment, so the accuracy requirements for current measurement are particularly strict. This accuracy is measured as a percentage of the rated value, so the rating is often divided into smaller units. In other words, when a panel is used that integrates the section containing the current measurement device with the other main circuit components, it is necessary to prepare a large number of current measurement devices required for each current rating, in addition to the many other main circuit components with different requirements.

[0012] Therefore, a structure that combines parts selected based on different criteria into a single panel requires advance preparation for all main circuit parts in accordance with the load, which increases the design man-hours and is economically undesirable.

[0013] The power conversion system shown in FIG. 1 has the following problems.

[0014] 1. If the current control accuracy required for the load changes, the current rating cannot be changed. Therefore, if there is no device with a matching current rating, it is necessary to develop a new device with an optimized current rating, and it is not easy to change the current rating.

[0015] 2. When a power converter consisting of semiconductor components and a circuit with current measuring devices, switches, and reactors dedicated to each current rating before and after the capacitor of the filter circuit are configured in a single panel, changing the current rating requires a redesign of the panel. Changing the layout of components through a design change can change the air flow and affect cooling performance. This requires a reevaluation of the panel, including the power converter consisting of semiconductor components, which incurs significant reevaluation costs and makes it difficult to change the current rating.

[0016] As described above, the challenge for power conversion systems is to reduce the range of influence when the current rating is changed, thereby reducing design and evaluation costs and resulting in a low-cost device, while also making it easy to change the current rating.

[0017] The present invention was devised in view of the above-mentioned problems of the conventional art, and one aspect of the present invention is a power conversion system consisting of multiple panels, comprising a power conversion device, a current measuring device connected between the power conversion device and a load and capable of detecting a current of a rated current corresponding to the load, a filter circuit having at least a reactor and a capacitor, and a control device that controls the power conversion device, characterized in that the power conversion device and the control device are housed in a first panel, and the current measuring device and the filter circuit are housed in a second panel.

[0018] In one aspect, the power supply is characterized by having a plurality of current measuring devices with different current ratings, a plurality of reactors corresponding to each of the plurality of current measuring devices, a plurality of current rated circuits including at least one of the current measuring devices and at least one of the reactors, and a switch for switching between the plurality of current rated circuits.

[0019] In one embodiment, the second board is provided with a relay circuit that converts the output signal of the current measuring device, and the current measuring device is connected to the control device via the relay circuit.

[0020] In another aspect, a power conversion system consisting of a plurality of panels includes a power conversion device, a plurality of current measuring devices connected between the power conversion device and a load and capable of detecting currents of different current ratings, a filter circuit having a capacitor and a plurality of reactors corresponding to each of the current measuring devices, a plurality of current rated circuits including at least one of the current measuring devices and at least one of the reactors, a switch for switching between the plurality of current rated circuits, and a control device for controlling the power conversion device, wherein the power conversion device and the control device are stored in a first panel, the reactor on a current path that is common regardless of which of the current rated circuits is selected from the plurality of filter circuits and the switch on the current path that is common regardless of which of the current rated circuits is selected are stored in a third panel, and the current measuring devices, the filter circuits, and the switch that are not stored in the third panel are stored in a second panel.

[0021] According to the present invention, in a power conversion system, the range of influence when the current rating is changed is reduced, thereby reducing the cost of design and evaluation, resulting in a low-cost device and making it easier to change the current rating.

[0022] 1 is a diagram showing an example of the configuration of a conventional power conversion system; 2 is a diagram showing the configuration of a power conversion system according to a first embodiment; 3 is a diagram showing the configuration of a current measurement in a control device according to the first embodiment; 4 is a diagram showing the configuration of a control unit according to the first embodiment; 5 is a diagram showing the configuration of an LCL filter circuit; 6 is a diagram showing the configuration of a power conversion system according to a second embodiment; 7 is a diagram showing the configuration of a power conversion system according to a third embodiment; 8 is a diagram showing the configuration of a current measurement in a control device according to the third embodiment; 9 is a diagram showing the configuration of a relay circuit according to the third embodiment; 10 is a diagram showing the configuration of a power conversion system according to a fourth embodiment;

[0023] 2 to 10. In this specification, "rated input voltage" refers to "a voltage specified as the peak value or root mean square of a DC or AC voltage that can be used as an input, and is often a voltage having a range that is specified to prevent device failure due to a significant excess or device malfunction due to a significant shortage," and "rated current" refers to "a current specified as the maximum peak value or root mean square of a DC or AC current that is assumed as an input / output current."

[0024] 2 shows a device configuration diagram of a power conversion system according to the present embodiment 1. In the present embodiment 1, a "first power conversion device 1 using semiconductor elements" and a "filter circuit (here, an LCL filter), a current measuring device, and an output switch" are housed in separate panels.

[0025] Specifically, a front-end current measuring device HCT_A11, a front-end reactor L_A11, a rear-end current measuring device HCT_B11, a rear-end reactor L_B11, and an output switch MC_C11 are provided between the first power conversion device 1 and the load 10. A capacitor C11 of a filter circuit is connected between the connection point of the front-end reactor L_A11 and the rear-end current measuring device HCT_B11 and the negative electrode of the first power conversion device 1. The front-end reactor L_A11, the capacitor C11, and the rear-end reactor L_B11 configure a filter circuit (LCL filter).

[0026] The power conversion system assumed in the first embodiment differs depending on the type of filter circuit. For example, if the filter circuit type is LC or LCL, the device is a device that outputs direct current, such as AC / DC (alternating current-direct current) or DC / DC (direct current-direct current), or a device that outputs alternating current, such as AC / AC (alternating current-alternating current) or DC / AC (direct current-alternating current), but at a frequency band sufficiently lower than the resonant frequency of the filter circuit. If the filter circuit type is only L, any type, such as AC / DC (alternating current-direct current), DC / DC (direct current-direct current), AC / AC (alternating current-alternating current), or DC / AC (direct current-alternating current), is acceptable. Furthermore, in the first embodiment, the switch is, for example, an electromagnetic contactor, but may also be a switch that can open and close a circuit, such as a disconnector.

[0027] The "first power conversion device 1" is housed in the first panel A1, and the "filter circuit, front-stage current measurement device HCT_A11, rear-stage current measurement device HCT_B11, output switch MC_C11" is housed in the second panel A2. A control device 20 that controls the first power conversion device 1 is installed in the first panel A1, and the control device 20 detects the output from the current measurement devices HCT (HCT_A11, HCT_B11).

[0028] 3 shows the current detection configuration of the control device 20. The output of the current measuring device HCT is directly input to the control device 20 and is input to the control section 22 via a detection circuit 21 as a digital signal.

[0029] 4 shows a circuit configuration diagram of the control unit 22. The control unit 22 receives the output of the current measurement device HCT, which is a digital signal input via the detection circuit 21, as a current detection value. To use the digital value as a current detection value inside the control unit 22, the multiplication unit 23 multiplies it by a current detection gain to convert it into a current value. This converted current value is applied to each process within the control unit 22. The current detection gain is defined in the control unit 22 as a parameter that can be changed from an external interface.

[0030] In applications requiring high current control accuracy, the control accuracy is significantly affected by the current detection resolution including the current measurement device HCT and the detection circuit 21. In addition, to reduce the current ripple that depends on the carrier frequency, it is necessary to change the constants of the filter circuit according to the required current ripple value.

[0031] The current detection resolution is expressed by equation (1). Here, the current detection resolution indicates the current value per bit of the AD converter (detection circuit 21). The current detection resolution is particularly affected by the rated current of the AD converter (detection circuit 21) and the current measurement device HCT. The current measurement device HCT needs to be changed depending on the output current.

[0032]

[0033] The current detection value used in each process of the control unit 22 is expressed by equation (2).

[0034]

[0035] Next, the circuit configuration of the filter circuit is shown in Figure 5. Here, L1 is the upstream reactor of the filter circuit, C2 is the capacitor of the filter circuit, L3 is the downstream reactor of the filter circuit, V1 is the voltage applied to the filter circuit, I1 is the current flowing in the upstream reactor, I2 is the current flowing in the capacitor, and I3 is the current flowing in the downstream reactor.

[0036] The transfer function when voltage V1 is input and current I3 is output is shown in equation (3). s represents the Laplace operator. Since carrier frequency ripple cannot be suppressed by control, it must be suppressed by a filter circuit. As shown in equation (3), it can be seen that the frequency characteristics of a filter circuit are greatly affected by the circuit constants of the filter circuit.

[0037]

[0038] 2, components of the current measuring device HCT and filter circuit that may be changed are stored in the second panel A2 and are ready to be connected to the first panel A1. In this way, if the constants of the current measuring device HCT or filter circuit need to be changed depending on the control accuracy or current ripple value required by the load 10, it is possible to accommodate this by changing only the second panel A2.

[0039] When the current measurement device HCT is changed, the current detection gain must be changed accordingly. The current detection gain is parameterized and can be changed from an external device. This allows the current detection gain to be set appropriately even when the current measurement device HCT is changed, so that processing that uses current information can also be performed appropriately.

[0040] If the current measuring device HCT and the filter circuit are installed in the first panel A1, it is necessary to change the first panel A1 every time the constants of the current measuring device HCT or the filter circuit are changed. When making such changes, the air flow inside the panel changes, which affects the cooling performance, so it becomes necessary to conduct a temperature rise test on the first power conversion device 1 to confirm that there are no problems with performance.

[0041] Therefore, compared to the configuration of this embodiment 1 in which the current measuring device HCT and filter circuit are not housed in the first panel A1, the scope of changes is wider, including the first power conversion device 1, the current measuring device HCT, and the filter circuit.

[0042] In the first embodiment, the range of changes to be made is narrower than in the configuration of the prior art, so the amount of work required for the changes is small, which leads to a reduction in development costs and ultimately leads to cost reduction. In addition, by changing the second panel A2 and the current detection gain, it is possible to easily change the current rating to an appropriate value according to the load 10.

[0043] As described above, according to the first embodiment, the current measuring device can be individually changed in accordance with the current rating, so that the ratio of the resolution to the rating can be ensured.

[0044] Furthermore, by separating units that are specifically defined by current ratings from units that are broadly defined by current ratings or input voltages, and combining units that have been prepared in advance for each unit as a divided panel, it is possible to provide a device that can accommodate a variety of loads 10.

[0045] In the first embodiment, the "units that are divided into more detail and determined by the current rating" correspond to the "current measuring device, filter circuit, and output switch." The current measuring device is required to have high resolution and detection accuracy, and it is preferable that it can handle ratings in many fine units. While making it possible to easily change the current gain, etc., it also reduces the effort required to change the design to suit the load 10.

[0046] In the first embodiment, the "unit determined by a wide range of current ratings or input voltages" corresponds to the "power conversion device and control device."

[0047] By configuring the "power conversion device and control device" and the "filter circuit, current measurement device, and output switch" in separate panels and configuring the current detection gain to be easily changed externally, the scope of changes required when changing the "filter circuit, current measurement device, and output switch" is reduced compared to conventional panel configurations. This reduces the labor costs required when making design changes, resulting in cost reductions.

[0048] Furthermore, filter circuits need to be changed not only depending on the current but also on the voltage rating, etc. Therefore, by simply preparing current measurement devices and filter circuits that have been individually pre-verified, it is possible to support a large number of combinations. This eliminates the need to ensure quality assurance for a large number of combinations in advance, making it possible to provide device configurations tailored to the load at the test site more economically.

[0049] The effect of this embodiment 1 is particularly pronounced when applied to a charging / discharging device. Specifically, charging / discharging devices require strict current measurement accuracy, and because this accuracy is a percentage of the rated current, the rating is often divided into smaller increments. When integrating a panel that includes a current measurement device with other main circuit components, a large number of current measurement devices required for each current rating must be combined with pre-prepared components for the other main circuit components with numerous different requirements. Therefore, an integrated panel structure requires pre-preparation for all main circuit components according to the load, which increases design man-hours and is economically undesirable. According to this embodiment 1, when changing the "filter circuit, current measurement device, and output switch," the scope of changes required is reduced compared to conventional panel configurations. This reduces the labor costs involved in design changes, ultimately leading to cost savings.

[0050] The following technical challenges exist in placing the "power conversion device made up of semiconductor components" and the "filter circuit / current measurement device" on separate panels and achieving current detection that matches the output of the current measurement device. 1. Changing the current detection gain when handling digital values ​​after AD conversion by a CPU, FPGA, etc. 2. Changing the panel configuration so that the "power conversion device made up of semiconductor components" and the "filter circuit / current measurement device" are on separate panels. 3. Changing the analog signal interface of the current measurement device output.

[0051] This point is not taken into consideration in Patent Document 1 and the circuit in Fig. 1, and therefore it is believed that it was not possible to separate the "power conversion device made up of semiconductor components" and the "current measurement device and filter circuit" onto different panels. This technical problem is solved simultaneously in the first embodiment. As a result, high current detection accuracy is achieved by separating the current measurement device and filter circuit onto different panels and easily changing these separated panels according to the current rating.

[0052] As described above, in a charge / discharge test device using a power conversion system consisting of multiple panels that requires advance preparation such as thermal design, particularly assuming a large capacity test load (approximately 1 kV / 1 kA, mainly targeting batteries and other power storage devices), by providing parts with different current rating requirements on different panels, it becomes easy to change the design to suit the load.

[0053] [Embodiment 2] Figure 6 shows a device configuration diagram of a power conversion system in embodiment 2. The difference from embodiment 1 is that the device configuration has a plurality of different current ratings. To achieve the plurality of current ratings, the system is equipped with a plurality of current measuring devices with different current ratings, a plurality of reactors corresponding to each of the plurality of current measuring devices, a plurality of current rating circuits including at least one of the current measuring devices and at least one of the reactors, and a switch for switching between the plurality of current rating circuits. The second panel A2 has a circuit with three current measuring devices for three current ratings, each before and after the capacitor of the filter circuit.

[0054] Specifically, a front-stage current measuring device HCT_A11, a first front-stage reactor L_A11, a first front-stage switch MC_A11, a first rear-stage switch MC_B11, a first rear-stage current measuring device HCT_B11, a first rear-stage reactor L_B11, and an output switch MC_C11 are connected between the first power conversion device 1 and the load 10.

[0055] A capacitor C11 of a filter circuit is connected between the connection point of the first front-stage side switch MC_A11 and the first rear-stage side switch MC_B11 and the negative electrode of the first power conversion device 1.

[0056] A second upstream current measuring device HCT_A21, a second upstream reactor L_A21, and a second upstream switch MC_A21 are connected in parallel to the first upstream reactor L_A11 and the first upstream switch MC_A11. Also, a third upstream current measuring device HCT_A31, a third upstream reactor L_A31, and a third upstream switch MC_A31 are connected in parallel to the first upstream reactor L_A11 and the first upstream switch MC_A11.

[0057] A second rear-stage side switch MC_B21 and a second rear-stage side current measuring device HCT_B21 are connected in parallel to the first rear-stage side switch MC_B11. A third rear-stage side switch MC_B31 and a third rear-stage side current measuring device HCT_B31 are connected in parallel to the first rear-stage side switch MC_B11.

[0058] Here, the first front-stage switch MC_A11, the second front-stage switch MC_A21, the third front-stage switch MC_A31, the first rear-stage switch MC_B11, the second rear-stage switch MC_B21, the third rear-stage switch MC_B31, and the output switch MC_C11 are switches that switch between multiple current-rated circuits.

[0059] In this second embodiment, the correspondence between the magnitude of the current rating and each current measuring device is defined as shown in Table 1, and the correspondence between the magnitude of the current rating and each switch is defined as shown in Table 2. Also, each current rating is configured to have a reactor to reduce current ripple. In this second embodiment, there are three current rating circuits, but the number of current rating circuits may be N (N = an integer of 2 or more).

[0060]

[0061]

[0062] Even when there are multiple current ratings, the first panel A1 houses the "first power conversion device 1 and control device 20," and the second panel A2 houses the "filter circuit, current measuring device HCT, switches MC_A11, MC_A21, MC_A31, MC_B11, MC_B21, MC_B31, and output switch MC." If you want to change only the medium and small current ratings on the second panel A2, you can simply change the medium and small current measuring device HCT and reactor. If you change the current detection gain accordingly, the current rating can be easily changed. In this case, the only part that needs to be changed is the second panel A2, so there is no need to change the first panel A1.

[0063] As described above, the second embodiment provides the same effects as the first embodiment.

[0064] In the second embodiment, the "units that are divided into more detail and determined by current rating" are "current measuring devices, filter circuits, switches, and output switches."

[0065] As in the first embodiment, the cost of work required for design changes is reduced, which ultimately leads to cost reduction.

[0066] 7 shows a device configuration diagram of a power conversion system according to the third embodiment. The difference from the second embodiment is that a relay circuit 24 is installed in the second panel A2. The output of the current measuring device HCT is input to the relay circuit (signal normalization circuit) 24, and the signal is converted (normalized) and then input to the control device 20.

[0067] Fig. 8 shows a circuit configuration diagram of the relay circuit 24, and Fig. 9 shows a circuit configuration diagram of the control device 20. As shown in Fig. 8, the output of the current measurement device HCT is input directly to the relay circuit 24 and then to the interface adjustment circuit 25, where it is converted into a signal form detectable by the control device 20. The converted signal is input to the control device 20, and as shown in Fig. 9, it is input as a digital signal to the control unit 22 via the detection circuit 21. The control unit 22 and subsequent components are the same as those in the first embodiment.

[0068] Depending on the type of current measuring device HCT, the output form of the current measuring device HCT may be voltage or current. In the case of voltage output, the rated voltage and rated output voltage of the current measuring device HCT differ depending on the type of current measuring device HCT. This is also true for current output.

[0069] Equation (4) shows the current detection value in the control unit 22 in this embodiment 3. The current value detected by the current measuring device HCT is multiplied by the conversion gain of the interface adjustment circuit 25 to convert it into a form detectable by the control device 20. As a result, the relay circuit 24 converts the output of the current measuring device HCT into a voltage or current form detectable by the control device 20, so even if the output form of the current measuring device HCT is changed, there is no need to change the range of the first panel A1. Therefore, only the second panel A2 needs to be changed, which keeps the development scope small and makes changes easy.

[0070]

[0071] As described above, the third embodiment has the same effects as the first embodiment.

[0072] In the third embodiment, the "units that are divided into more detail and determined by the current rating" are "current measuring devices, filter circuits, switches (switching devices), output switches, and relay circuits." This eliminates the need to change the control device 20 when changing the current rating.

[0073] Since only the second board A2 needs to be changed, the labor costs involved in changing the design are reduced, resulting in cost reduction.

[0074] 10 shows a device configuration diagram of a power conversion system according to the present embodiment 4. The difference from the embodiment 3 is that the first downstream reactor L_B11 and the output switch MC_C11, which are common to the current paths of all current-rated circuits, are not housed in the second panel A2 but in the third panel A3.

[0075] In the case of an application in which only the current measuring devices HCT and reactors with medium and small current ratings are changed, no change is required in the third panel A3. In the methods up to the third embodiment, the first rear-stage reactor L_B11 and output switch MC_C11 were included in the second panel A2, so if the configuration of the panel changes due to a change in the first front-stage reactor L_A21 or the third front-stage reactor L_A31 and this affects cooling performance, the first rear-stage reactor L_B11 and output switch MC_C11 will be included in the confirmation range of the temperature rise test.

[0076] With the device configuration of the fourth embodiment, the first downstream reactor L_B11 and output switch MC_C11 are not included in the confirmation range because they are separated into panels. This reduces the confirmation range, making it possible to reduce the evaluation man-hours. Also, while it was previously necessary to change the second panel A2 if the first downstream reactor L_B11 and output switch MC_C11 were evaluated as NG when checked, this need not be a concern with the configuration of the second embodiment.

[0077] As described above, according to this embodiment 4, the same effects as those of embodiment 1 are achieved. Furthermore, by placing some of the reactors mounted on the panel in which the current measuring device of embodiment 3 was located on a separate panel, when converting between current measuring devices and reactors with medium and small current ratings, only the second panel A2 needs to be changed, which reduces the work costs involved in changing the design and ultimately leads to cost reductions.

[0078] Although the present invention has been described in detail above only with respect to the specific examples, it will be apparent to those skilled in the art that various modifications and variations are possible within the scope of the technical concept of the present invention, and it is natural that such modifications and variations fall within the scope of the claims.

[0079] 1...First power conversion device 10...Load 20...Control device 21...Detection circuit 22...Control unit 23...Multiplier 24...Relay circuit 25...Interface adjustment circuit A1...First panel A2...Second panel A3...Third panel

Claims

1. A power conversion system consisting of multiple panels, comprising: a power conversion device; a current measuring device connected between the power conversion device and a load and capable of detecting a current rated for the load; a filter circuit having at least a reactor and a capacitor; and a control device for controlling the power conversion device, wherein the power conversion device and the control device are housed in a first panel, and the current measuring device and the filter circuit are housed in a second panel.

2. The power conversion system according to claim 1, characterized in that it comprises: a plurality of current measuring devices with different current ratings; a plurality of reactors corresponding to each of the plurality of current measuring devices; a plurality of current rated circuits including at least one of the current measuring devices and at least one of the reactors; and a switch for switching between the plurality of current rated circuits.

3. The power conversion system according to claim 1, wherein the second board is provided with a relay circuit that converts the output signal of the current measuring device, and the current measuring device is connected to the control device via the relay circuit.

4. A power conversion system comprising a plurality of panels, comprising: a power conversion device; a plurality of current measuring devices connected between the power conversion device and a load and capable of detecting currents of different current ratings; a filter circuit having a capacitor and a plurality of reactors corresponding to each of the plurality of current measuring devices; a plurality of current rated circuits including at least one of the current measuring devices and at least one of the reactors; a switch for switching between the plurality of current rated circuits; and a control device for controlling the power conversion device, wherein the power conversion device and the control device are stored in a first panel, the reactor on a current path that is common regardless of which of the current rated circuits is selected from the plurality of filter circuits and the switch on a current path that is common regardless of which of the current rated circuits is selected are stored in a third panel, and the current measuring devices, the filter circuits, and the switch that are not stored in the third panel are stored in a second panel.

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