Power conversion device

Abstract

To provide a power conversion device having a plurality of functions such as solar power generation, a stationary storage battery, and an EV charger, and suppressing fluctuations in DC voltage in a power converter even when power from the solar power generation or the stationary storage battery changes steeply.SOLUTION: In a power conversion device in which a plurality of power conversion units are mounted in the same cabinet, the plurality of power conversion units are connected by common DC wiring and are classified into two groups according to the magnitude of a time constant of control of each power conversion unit, and the plurality of power conversion units belonging to a group having a smaller time constant of control of the two groups are disposed adjacent to each other in the cabinet.SELECTED DRAWING: Figure 5

Description

Technical Field

[0001] The present invention relates to a power conversion device including a plurality of power conversion units having different control time constants.

Background Art

[0002] Against the backdrop of decarbonization, the introduction of renewable energy such as solar power generation and the introduction of electric vehicles (EVs) are progressing. In addition, for the purpose of effectively utilizing renewable energy, the introduction of stationary batteries is also progressing. When introducing these devices into buildings such as buildings, there may be limited installation space, so downsizing of the devices is required. As one means of realizing downsizing of devices, there is a method of mounting the functions of solar power generators, EV chargers, and stationary batteries in one power conversion device. In this case, the main circuits of AC / DC conversion for converting three-phase alternating current to direct current, non-insulated DC / DC conversion for converting the DC power of solar panels and batteries, and insulated DC / DC conversion for charging the batteries of EVs may be mounted in individual units, respectively, and these units may be combined to configure a power conversion device with a combined function. For example, Patent Document 1 describes a connection method for these power conversion units.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] Patent Document 1 describes the arrangement of units inside a power conversion device and the connection method to busbar wiring for miniaturizing the power conversion device. For example, consider a power converter incorporating units for non-insulated DC / DC conversion for solar power generation or stationary batteries, insulated DC / DC conversion for EV charging, and AC / DC conversion for converting three-phase AC to DC. In EV charging, a current is output based on a command value from the EV to charge the battery inside the EV. Since this operation is a control that changes the command value according to the state of charge of the battery, the output current does not change suddenly, and the time constant of the control does not have to be very small.

[0005] Here, the time constant of control is an exponent indicating the response speed in a control system and represents the time until the output reaches about 63% of the input. Generally, if the output is OUT, the input is IN, and the time constant is T, it is expressed by the following formula. OUT = IN × (1 - e·EXP(-t / T)) From this formula, it can be seen that the larger the time constant T, the slower the increase rate of the output value, that is, the slower the response speed.

[0006] As described above, in EV charging, the time constant of control is large. On the other hand, in the case of solar power generation, it is necessary to continue power generation even in a state where the weather changes suddenly, such as from sunny to cloudy, so the time constant of its control is smaller than that of EV charging. Regarding stationary batteries, when used for power energy management in buildings or factories, the change in input / output power from the battery is also large to cope with sudden changes in the load, and the time constant of control becomes smaller than that of EV charging.

[0007] As described above, the power from solar power generation or stationary batteries exchanges power with the three-phase AC power distribution within the system or facility through AC / DC conversion. However, when a non-insulated DC / DC conversion unit with a small time constant in solar power generation or stationary batteries is arranged separately from the AC / DC conversion unit, the following problems may occur. That is, when the power from the non-insulated DC / DC conversion units of solar power generation or stationary batteries changes steeply, the DC voltage fluctuates due to the impedance of the busbar wiring connecting these units, and there is a risk that the output voltage will not stabilize.

[0008] The present invention has been made in view of the above problems, and its object is to provide a power conversion device incorporating an AC / DC conversion unit that mutually converts three-phase AC and DC, a non-insulated DC / DC conversion unit for solar power generation or stationary batteries, and an insulated DC / DC conversion unit for EV charging, which can suppress fluctuations in the internal DC voltage even when the power from solar power generation or stationary batteries changes steeply.

Means for Solving the Problems

[0009] In order to solve the above problems, a power conversion device according to the present invention is a power conversion device in which a plurality of power conversion units are mounted in the same cabinet. The plurality of power conversion units are connected by a common DC wiring and are classified into two groups according to the magnitude of the control time constant of each power conversion unit. A plurality of power conversion units belonging to the group with a small control time constant among the two groups are arranged adjacent to each other within the cabinet.

Effects of the Invention

[0010] According to the present invention, fluctuations in the DC voltage within the power conversion device can be suppressed even when the power from solar power generation or stationary batteries changes steeply. Further features related to the present invention will become apparent from the description of this specification and the accompanying drawings. Also, problems, configurations, and effects other than those described above will be clarified by the description of the following embodiments.

Brief Description of the Drawings

[0011]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Mode for Carrying Out the Invention

[0012] Hereinafter, embodiments will be described with reference to the drawings. [Embodiment 1] First, Embodiment 1 will be described with reference to FIGS. 1 to 5. FIG. 1 shows an example of the circuit configuration of an AC / DC conversion unit 101 that converts three-phase alternating current to direct current (or vice versa). The AC / DC conversion unit 101 includes a three-phase full-bridge circuit 102, a DC wiring 103, a capacitor 104, a filter circuit 105, a gate drive circuit and its control circuit 106, and input / output terminals 107 and 108. Also, the time constant of the AC / DC conversion unit 101 is relatively small.

[0013] The three-phase full-bridge circuit 102 is a known bridge circuit that converts three-phase alternating current to direct current or direct current to three-phase alternating current. The capacitor 104 functions to stabilize the voltage of the DC wiring 103. The filter circuit 105 consists of a reactor and a capacitor. The gate drive circuit and its control circuit 106 drive the three-phase full-bridge circuit 102. The input / output terminals 107 are for three-phase alternating current, and the input / output terminals 108 are DC terminals connected to the DC wiring 502 of the power conversion device described later.

[0014] FIG. 2 shows an example of the circuit configuration of the non-insulated DC / DC conversion unit 201 used for solar power generation. The non-insulated DC / DC conversion unit 201 includes a switching circuit 202, an inductor 203, a gate drive circuit and its control circuit 204, a DC wiring 205, a capacitor 206, and input / output terminals 207 and 208. Also, the time constant of the non-insulated DC / DC conversion unit 201 used for solar power generation is relatively small, similar to that of the AC / DC conversion unit 101.

[0015] The switching circuit 202 includes known switching elements and, together with the inductor 203, converts the DC voltage obtained by the solar power generation device into a voltage that is easy to use. The gate drive circuit and its control circuit 204 drive the switching circuit 202. The capacitor 206 functions to stabilize the voltage of the DC wiring 205. The input / output terminal 207 is connected to the DC wiring 502 of the power conversion device, and the input / output terminal 208 is connected to the DC load of the solar panel.

[0016] FIG. 3 shows an example of the circuit configuration of the non-insulated DC / DC conversion unit 301 used for stationary batteries. The non-insulated DC / DC conversion unit 301 includes a switching circuit 302, an inductor 303, a gate drive circuit and its control circuit 304, a DC wiring 305, a capacitor 306, and input / output terminals 307 and 308. Also, the time constant of the non-insulated DC / DC conversion unit 301 used for stationary batteries is relatively small, similar to those of the above two units.

[0017] The switching circuit 302 includes known switching elements and converts the DC voltage output from the stationary battery together with the inductor 303 into a voltage that is easy to use. The gate drive circuit and its control circuit 304 drive the switching circuit 302. The capacitor 306 functions to stabilize the voltage of the DC wiring 305. The input / output terminal 307 is connected to the DC wiring 502 of the power conversion device, and the input / output terminal 308 is connected to the DC load of the stationary battery.

[0018] FIG. 4 shows an example of the circuit configuration of the isolated DC / DC conversion unit 401 used in the EV charger. The isolated DC / DC conversion unit 401 includes single-phase full-bridge circuits 402 and 403, a transformer 404, capacitors 405 and 406, a gate drive circuit and its control circuit 407, and input / output terminals 408 and 409. Also, the time constant of the isolated DC / DC conversion unit 401 used in the EV charger is relatively large compared to the above three units.

[0019] The single-phase full-bridge circuits 402 and 403 are respectively connected to the DC wiring side in the power conversion device on the primary side and the EV side on the secondary side. The transformer 404 is mounted between these two full-bridge circuits to transform the voltage. The capacitors 405 and 406 function to stabilize the voltage in any of the DC wirings on the primary side and the secondary side. The gate drive circuit and its control circuit 407 drive the single-phase full-bridge circuits 402 and 403. Also, the input / output terminal 408 is connected to the DC wiring 502 of the power conversion device, and the input / output terminal 409 is connected to the DC load of the EV battery.

[0020] The mounting forms of the AC / DC conversion unit 101, the non-insulated DC / DC conversion unit 201 for solar power generation, the non-insulated DC / DC conversion unit 301 for stationary batteries, and the insulated DC / DC conversion unit 401 for EV charging, which were described above, are shown in FIG. 5. The converter panel includes a cabinet 501 on which each of the above units is mounted, and a DC wiring 502 installed along the back surface of the cabinet 501. The converter panel also includes a three-phase AC wiring 503 at the lower part of the back surface of the cabinet 501, a DC wiring 504 connected to the solar panel, and a DC wiring 505 connected to the stationary battery. Further, a DC wiring 506 for connection to the EV is provided at the upper part of the back surface of the cabinet 501.

[0021] The AC / DC conversion unit 101 is arranged at the lowermost stage of the cabinet 501. The three-phase AC input / output terminals 107 on the back surface of the AC / DC conversion unit 101 are connected to the three-phase AC wiring 503 in the cabinet 501. Similarly, the DC input / output terminals 108 on the back surface of the AC / DC conversion unit 101 are connected to the DC wiring 502 in the cabinet 501.

[0022] The non-insulated DC / DC conversion unit 201 for solar power generation is arranged immediately above the AC / DC conversion unit 101 in the cabinet 501. The DC input / output terminals 207 on the back surface of the non-insulated DC / DC conversion unit 201 for solar power generation are connected to the DC wiring 502 in the cabinet 501. Similarly, the terminals 208 connected to the DC load of the solar panel on the back surface of the non-insulated DC / DC conversion unit 201 for solar power generation are connected to the DC wiring 504 connected to the solar panel in the cabinet 501.

[0023] The non-insulated DC / DC conversion unit 301 for stationary batteries is arranged immediately above the non-insulated DC / DC conversion unit 201 for solar power generation within the cabinet 501. The DC input / output terminal 307 on the back of the non-insulated DC / DC conversion unit 301 for stationary batteries is connected to the DC wiring 502 within the cabinet 501. Similarly, the input / output terminal 308 on the back of the non-insulated DC / DC conversion unit 301 for stationary batteries is connected to the DC wiring 505 that is connected to the stationary batteries within the cabinet 501.

[0024] In FIG. 5, the AC / DC conversion unit 101, the non-insulated DC / DC conversion unit 201 for solar power generation, and the non-insulated DC / DC conversion unit 301 for stationary batteries are mounted in this order from the bottom of the cabinet 501. However, the arrangement order of these three types of power conversion units may be arbitrary. In other words, these units with relatively small control time constants may be arranged adjacent to each other, and the order does not matter. By adopting such a configuration, the length of the DC wiring 502 connecting the units is shortened, the increase in impedance is suppressed, and the increase in DC voltage can be suppressed. Also, only one of the non-insulated DC / DC conversion unit 201 for solar power generation and the non-insulated DC / DC conversion unit 301 for stationary batteries may be mounted.

[0025] An insulated DC / DC conversion unit 401 for EV charging is mounted on the upper part of the cabinet 501. The DC input / output terminal 408 on the back of the insulated DC / DC conversion unit 401 for EV charging is connected to the DC wiring 502 within the cabinet 501. Similarly, the input / output terminal 409 on the back of the insulated DC / DC conversion unit 401 for EV charging is connected to the DC wiring 506 for connecting to the EV within the cabinet 501. Thus, the insulated DC / DC conversion unit 401 for EV charging, which has a larger control time constant compared to the above-mentioned three types of power conversion units, is arranged adjacent to the unit arranged at the outermost end among the power conversion units with a smaller control time constant. Also, all the above-mentioned units are connected by a common DC wiring.

[0026] By adopting the mounting structure of each power conversion unit shown in FIG. 5, the non-insulated DC / DC conversion unit 201 for solar power generation and the non-insulated DC / DC conversion unit 301 for stationary storage batteries, where the DC power changes steeply, are arranged in the vicinity of the AC / DC conversion unit 101, so that fluctuations in the DC voltage within the power conversion device can be suppressed. That is, for example, assuming a configuration in which a power conversion unit with a large control time constant is sandwiched by power conversion units with a small control time constant, when the power changes steeply, the impedance increases in the part of the power conversion unit with a large control time constant, and the DC voltage fluctuates greatly before reaching the adjacent power conversion unit with a small control time constant, making the operation of the power conversion unit unstable. However, by adopting the configuration as in this embodiment, such problems can be avoided.

[0027] When organizing the configuration in this embodiment, the power conversion device shown in FIG. 5 is a power conversion device in which a plurality of power conversion units 101, 201, 301, and 401 are mounted in the same cabinet 501. These power conversion units are connected by a common DC wiring 502 and are classified into two groups according to the magnitude of the time constant. The power conversion units 101, 201, and 301 belonging to the group with a small time constant among the two groups are arranged adjacent to each other in the cabinet 501.

[0028] In this embodiment, an AC / DC conversion unit 101, a non-insulated DC / DC conversion unit 201 for solar power generation, and a non-insulated DC / DC conversion unit 301 for stationary batteries, which are power conversion units with small control time constants, and an insulated DC / DC conversion unit 401 for EV charging, which is a power conversion unit with a large control time constant, are adopted. However, the power conversion units are not limited to these. For example, as power conversion units with small time constants, there are also inverter circuit units that rotate various motors. As power conversion units with large time constants, there are power supply units that supply power to loads such as coolers. Further, it is preferable that the average of the time constants in the group with large time constants is twice or more the average of the time constants in the group with small time constants.

[0029] [Embodiment 2] Next, the power conversion device according to Embodiment 2 of the present invention will be described with reference to FIG. 6. In FIG. 6, the same reference numerals as those in FIGS. 1 to 5 denote the same components, and thus the description thereof will be omitted. In Embodiment 1, only one of each of the AC / DC conversion unit 101, the non-insulated DC / DC conversion unit 201 for solar power generation, the non-insulated DC / DC conversion unit 301 for stationary batteries, and the insulated DC / DC conversion unit 401 for EV charging was mounted. However, Embodiment 2 is different from Embodiment 1 in that a plurality of these units are mounted respectively.

[0030] FIG. 6 shows a form in which a plurality of AC / DC conversion units 101, non-insulated DC / DC conversion units 201 for solar power generation, non-insulated DC / DC conversion units 301 for stationary batteries, and insulated DC / DC conversion units 401 for EV charging are each mounted. A plurality of AC / DC conversion units 101, a plurality of non-insulated DC / DC conversion units 201 for solar power generation, and a plurality of non-insulated DC / DC conversion units 301 for stationary batteries are arranged from below the lower part of the cabinet 501 of the power converter. Similar to Example 1, these three types of power conversion units may be arranged adjacent to each other, and the order may be arbitrary. Also, only one of the non-insulated DC / DC conversion unit 201 for solar power generation and the non-insulated DC / DC conversion unit 301 for stationary batteries may be mounted.

[0031] On the upper part of the cabinet 501 of the power converter, a plurality of insulated DC / DC conversion units 401 for EV charging are arranged.

[0032] By adopting the mounting structure of each power conversion unit shown in FIG. 6, even when a plurality of AC / DC conversion units 101, non-insulated DC / DC conversion units 201 for solar power generation, non-insulated DC / DC conversion units 301 for stationary batteries, and insulated DC / DC conversion units 401 for EV charging are mounted, the non-insulated DC / DC conversion unit 201 for solar power generation and the non-insulated DC / DC conversion unit 301 for stationary batteries, where the DC power changes steeply, are arranged near the AC / DC conversion unit 101. Therefore, similar to Example 1, the fluctuation of the DC voltage in the power conversion device can be suppressed.

[0033] [Modification Example] FIG. 7 is a diagram showing the configuration of a power conversion device according to a modified example of Example 2. Also in FIG. 7, similar to FIG. 6, a form in which a plurality of AC / DC conversion units 101, non-insulated DC / DC conversion units 201 for solar power generation, non-insulated DC / DC conversion units 301 for stationary batteries, and insulated DC / DC conversion units 401 for EV charging are each mounted is shown. In this modified example, the AC / DC conversion unit 101, the non-insulated DC / DC conversion unit 201 for solar power generation, and the non-insulated DC / DC conversion unit 301 for stationary batteries are arranged one by one in the vertical direction from the center at the lower part of the cabinet 501 of the power converter. Similar to Example 1 and Example 2, these three types of power conversion units may be arranged adjacent to each other, and the order is arbitrary. Also, only one of the non-insulated DC / DC conversion unit 201 for solar power generation and the non-insulated DC / DC conversion unit 301 for stationary batteries may be mounted.

[0034] One insulated DC / DC conversion unit 401 for EV charging is arranged at the uppermost and lowermost parts of the cabinet 501 of the power converter.

[0035] By adopting the mounting structure of each power conversion unit shown in FIG. 7, even when a plurality of AC / DC conversion units 101, non-insulated DC / DC conversion units 201 for solar power generation, non-insulated DC / DC conversion units 301 for stationary batteries, and insulated DC / DC conversion units 401 for EV charging are mounted, the non-insulated DC / DC conversion unit 201 for solar power generation and the non-insulated DC / DC conversion unit 301 for stationary batteries, where the DC power changes steeply, are arranged in the vicinity of the AC / DC conversion unit 101. Therefore, similar to Example 1 and Example 2, fluctuations in the DC voltage within the power conversion device can be suppressed.

[0036] According to the embodiments of the present invention described above, the following operational effects can be obtained.

[0037] (1) The power conversion device according to the present invention is a power conversion device in which a plurality of power conversion units are mounted in the same cabinet. The plurality of power conversion units are connected by a common DC wiring and are classified into two groups according to the magnitude of the control time constant of each power conversion unit. Among the two groups, a plurality of power conversion units belonging to the group with a smaller control time constant are arranged adjacent to each other in the cabinet.

[0038] With the above configuration, even when the power from solar power generation or a stationary battery changes steeply, fluctuations in the DC voltage within the power conversion device can be suppressed.

[0039] (2) The plurality of power conversion units include at least an AC / DC conversion unit that performs conversion between three-phase and DC, a solar power generation unit, a stationary battery unit, and an EV charging unit. These units are power conversion units that have been widely used in recent years.

[0040] (3) Among the two groups, the group with a smaller control time constant includes the AC / DC conversion unit, the solar power generation unit, and the stationary battery unit, and the group with a larger control time constant includes the EV charging unit. By dividing the two groups according to the control time constant, the above-described effects of the present invention can be obtained.

[0041] (4) Among the two groups, the average of the time constants of the power conversion units belonging to the group with the larger time constant is at least twice the time constant of the power conversion units belonging to the group with the smaller time constant. It is preferable to set the time constant threshold for dividing the groups in this way.

[0042] Note that the present invention is not limited to the above-described embodiments, and various modifications are possible. For example, the above embodiments have been described in detail for easy understanding of the present invention, but the present invention is not necessarily limited to the embodiments having all the configurations described. Also, it is possible to replace a part of the configuration of one embodiment with the configuration of another embodiment. Further, it is possible to add the configuration of another embodiment to the configuration of one embodiment. Also, it is possible to delete a part of the configuration of each embodiment, or add or replace other configurations.

Description of Reference Numerals

[0043] 101 ··· AC / DC conversion unit, 201 ··· non-insulated DC / DC conversion unit for solar power generation, 301 ··· non-insulated DC / DC conversion unit for stationary battery, 401 ··· insulated DC / DC conversion unit for EV charger, 501 ··· cabinet of power conversion device, 502 ··· DC wiring inside the cabinet of power conversion device

Claims

1. A power conversion device in which a plurality of power conversion units are implemented in the same cabinet, wherein the plurality of power conversion units are connected by a common DC wiring and classified into two groups according to the magnitude of the control time constant of each power conversion unit, and the plurality of power conversion units belonging to the group with a smaller control time constant among the two groups are arranged adjacent to each other in the cabinet. A power conversion device characterized by the above.

2. The power conversion device according to Claim 1, wherein the plurality of power conversion units include at least an AC / DC conversion unit that performs conversion between three-phase and DC, a solar power generation unit, a stationary battery unit, and an EV charging unit. A power conversion device characterized by the above.

3. The power conversion device according to Claim 2, wherein among the two groups, the group with a smaller control time constant includes the AC / DC conversion unit, the solar power generation unit, and the stationary battery unit, and the group with a larger control time constant includes the EV charging unit. A power conversion device characterized by the above.

4. The power conversion device according to Claim 1, wherein the average of the time constants of the power conversion units belonging to the group with the larger time constant among the two groups is at least twice the time constant of the power conversion units belonging to the group with the smaller time constant. A power conversion device characterized by the above.

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