JP2018042337A - Electric power conversion system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an electric power conversion system including an electric power conversion system housing suitable for being set in a photovoltaic power generation site.SOLUTION: A single phase inverter is comprised on a secondary side on a high frequency resonance converter of which an input is DC. Three electric conversion unit groups in which an output of an electric power conversion unit constructed by a high frequency transformer and components connected with a primary winding and a secondary winding side is serially connected are constructed and housed in an electric power conversion system housing to form AC 3-phase. The plurality of electric power conversion units are arranged in a longitudinal direction of the housing, and the three electric power conversion unit groups are arranged in an upper stage, a middle stage, a bottom stage of a height direction of the housing. The plurality of electric power conversion units transmit a generation heat of a component to a heat discharge part. The heat discharge part is arranged in a thermal conversion space formed on a rear side having an opening part along the longitudinal direction of the housing, and discharges an excessive heated air introduced from the opening part through a fan provided on the left and right in the longitudinal direction of the housing communicated with the thermal conversion space.SELECTED DRAWING: Figure 3

Description

  The present invention relates to a power conversion device.

  In order to link electric power from a power generation facility using natural energy, such as solar power generation or wind power generation, to a power system, a power conversion device that converts the voltage and frequency of the power system is used. The power conversion device includes a plurality of power conversion devices that perform power conversion between DC power and AC power. The power conversion device includes an insulating transformer and a power converter such as a DC / DC converter or an inverter. ing.

  In general, for example, in the case of a large-scale solar PCS, a direct current from a photovoltaic power generation facility is input, and three-phase power of about 400 V is output. The high voltage insulation transformer is used for the step-up output from the solar PCS to the high voltage system (6.6 kV, 22 kV, etc.), and it must be driven at the same low frequency of several tens of Hz as the system frequency. To do. In addition, in order to realize the outdoor installation of the PCS for large capacity, it is necessary to store the solar PCS in the container or to make the solar PCS itself an outdoor panel specification, which increases the size of the equipment.

  Furthermore, the loss can be further reduced by shortening the length of the DC wiring and low-voltage AC wiring. However, as described above, the volume and weight of the outdoor-use solar PCS and interconnection transformer are large, and the solar panel Since the most recent arrangement is difficult due to the influence of the shade on the solar panel, it is generally arranged away from the solar panel.

  Note that Patent Document 1 is known as an example in which a power converter is configured in a panel configuration in association with a transformer panel.

  In Patent Document 1, “an input transformer 1 having a plurality of secondary windings, a transformer panel 10 that houses the input transformers 1, and a one-to-one connection to the secondary windings, as desired. A three-phase inverter configured by Y-connecting a plurality of unit inverters 2 that serially connect a plurality of unit inverters 2 that output a single-phase AC voltage having a frequency of 5 and a converter panel 20 that houses the unit inverters 2 that constitute the three-phase inverter. The converter panel 20 includes a plurality of support posts 22 made of an insulating material and a plurality of metal shelf plates 23 for fastening the support posts 22 adjacent to each other in the lateral direction. The unit inverter 2 is mounted and fixed on the shelf plate 23, respectively. "

JP 2004-357436 A

  However, since the converter panel 20 has a high input / output voltage, it is necessary to take an insulation distance when taking the neutral point, and it is difficult to realize a reduction in size of the power converter.

  In view of the above, an object of the present invention is to provide a power converter that can be miniaturized.

  As described above, in the present invention, the high-frequency resonant converter having a DC input has a single-phase inverter on the secondary side, and is composed of a high-frequency transformer and parts connected to the primary and secondary windings. For the power conversion units, the single-phase inverter outputs of a plurality of power conversion units are connected in series to form a power conversion unit group, and each of the AC three-phases is composed of three sets of power conversion unit groups housed in the power converter housing. The plurality of power conversion units forming the phase and constituting the power conversion unit group are arranged along the longitudinal direction of the power conversion device casing, and the three sets of power conversion unit groups are the heights of the power conversion device casing. Are arranged in the upper, middle, and lower stages in the vertical direction, and one end side in the longitudinal direction of the power conversion device casing is used as an output terminal of the three power conversion unit groups. The terminals of the three power conversion unit groups are commonly connected on the other end side in the direction, and each of the plurality of power conversion units is a component connected to the high-frequency transformer and its primary winding and secondary winding side The heat generated by each of the plurality of power conversion units is formed along the longitudinal direction of the power conversion device casing and on the back side which is one surface having an opening. It is characterized in that superheated air introduced from the opening is exhausted through a fan provided in the left and right quality in the longitudinal direction of the power converter housing that is arranged and arranged in the space for heat exchange and communicates with the space for heat exchange. To do.

  An object of the present invention is to provide a power conversion device that can be miniaturized.

The figure which shows a front surface as an example of the housing | casing and arrangement | positioning positional relationship of the power converter device which concerns on this invention. The figure which shows an example of the photovoltaic power generation site where the power converter device of this invention is applied. The figure which shows the example of a connection of the several power conversion unit U in the power converter device housing | casing 100. FIG. The figure which shows the other example of a connection of the several power conversion unit U in the power converter device housing | casing 100. FIG. The figure which shows the structure of the electric circuit of the power converter device implement | achieved by the connection in the power converter device housing | casing 100 comprised as FIG. 3 or FIG. The figure which shows a rear surface as an example of the housing | casing and arrangement | positioning positional relationship of the power converter device which concerns on this invention. The figure which shows the mounting relationship of the power converter device housing | casing 100 and the internal three-phase power conversion unit group 1A. The figure which looked down from the upper part of the power converter device housing | casing 100. FIG. The perspective view of the power conversion unit U. FIG. The figure which looked at arrangement | positioning of the power conversion unit UW5 of FIG. 9 from the heat exchange part 73 side. The figure which shows the circuit structure of 2 in 1 unit supposing the case where input current is small about the circuit structure in the power conversion unit U. The figure which shows the structure which made the single phase inverter 2 steps | paragraphs 3 levels inverter about the circuit structure in the power conversion unit U. FIG. The figure which shows the example comprised with IGBT about the circuit structure in the power conversion unit U. FIG. The figure which shows the example of a connection of the several power conversion unit U in the power converter device housing | casing 100 in the case of employ | adopting Example 3. FIG. The figure which shows the circuit structural example in the power conversion unit U which concerns on Example 4. FIG.

  Hereinafter, the power converter of the present invention will be described with reference to the drawings.

  FIG. 1 is a diagram showing a housing and arrangement positional relationship of a power conversion device according to the present invention. The power conversion device casing 100 of the present invention is installed using a space formed between a solar panel PL and a base BB for mounting and supporting the solar panel PL. For this reason, it arrange | positions in the position where it does not receive direct sunlight, and is well-ventilated. The box-shaped housing has a box shape extending in the longitudinal direction. Incidentally, the length of the casing is 2.5 (m), the length in the short direction is 0.9 (m), the height is 0.7 (m), for example, It can be placed in a shaded space formed by the solar panel PL and the gantry BB.

  1 shows the shape of the front surface thereof, and FIG. 6 shows the shape of the rear surface thereof. The feature point here is that a cooling part is provided on the front and side surfaces, which will be described later in detail.

  FIG. 2 shows an example of a photovoltaic power generation site to which the power conversion device of the present invention is applied.

  The solar power generation site of FIG. 2 is formed by a plurality of solar panels PL mounted and supported on the gantry B, and the DC output of each solar panel PL is obtained between the terminals TD1 and TD2. In addition, the photovoltaic power generation site is provided with the power conversion device casing 100 of FIG. 1 that converts the direct current output of the solar panel PL into the three-phase alternating current of the power system using the lower space of the gantry BB. As will be described later, the box-shaped power conversion device housing 100 houses a plurality of power conversion units U (U1 and U2 in the drawing), and each power conversion unit U is a DC output terminal of each solar panel PL. DC input terminals TD1, TD2 connected to TL1, TL2 and AC output terminals TA1, TA2 are provided. The direct current output terminals TL1, TL2 of the solar panel PL1 are connected in association with, for example, the direct current input terminals TD1, TD2 of the power conversion unit U1, and the direct current output terminals TL1, TL2 of the solar panel PL2 are, for example, the power conversion unit. They are connected in association with the DC input terminals TD1 and TD2 of U2. Alternatively, the DC output terminals TL1 and TL2 of the plurality of solar panels PL are respectively connected in common and connected to the DC input terminals TD1 and TD2 of the power conversion unit U.

  FIG. 3 shows a connection example of a plurality of power conversion units U in the power conversion device casing 100.

  The external connection of the power conversion device housing 100 is connected to the DC input terminals TD1 and TD2 connected to the DC output terminals TL1 and TL2 of the plurality of solar panels PL and each phase of the high-voltage three-phase power system. The three-phase AC output terminals TU, TV and TW are used. A low voltage DC input is applied to the DC input terminals TD1, TD2, and a high voltage three phase output is applied from the three-phase AC output terminals TU, TV, TW.

  The three-phase AC output is a Y-connection that is grounded at a neutral point N, and three-phase AC output terminals TU, TV, and TW are provided at one end in the longitudinal direction of the box-shaped power converter housing 100. A neutral point N is arranged on the other end side in the longitudinal direction of the cubic power conversion device casing 100 in a centralized arrangement. The arrangement positions of the DC input terminals TD1 and TD2 are not particularly limited, but the illustrated example shows an example of arrangement on the neutral point N side of the other end in the longitudinal direction of the box-shaped power converter housing 100. ing. In the illustrated example, a DC circuit breaker MCCB is installed at the DC input terminals TD1 and TD2. In the illustrated example, the DC output terminals TL1 and TL2 of the plurality of solar panels PL are connected in common and connected to the DC input terminals TD1 and TD2 provided in common in the power conversion unit U.

  In the power converter housing 100, each phase between the three-phase AC output terminals TU, TV, TW and the neutral point N is configured by a plurality of power conversion units U. In the example shown in the figure, each phase is composed of eight power conversion units U. In the case of W phase, UWI, UW2, UW3, UW4, UW5, UW6, UW7, UW8 are arranged sequentially from the neutral point N side. doing. This arrangement is the same for the other phases.

  Further, in the power conversion device casing 100, power conversion unit groups each having eight power conversion units U are arranged in multiple stages in the height direction of the power conversion device casing 100. In the illustrated example, the power conversion unit group of each phase of U, V, and W employs a three-stage stacked structure in which the U phase is disposed in the lower stage, the V phase is disposed in the intermediate stage, and the W phase is disposed in the upper stage.

  FIG. 3 illustrates a configuration example of the UW 5 as a specific circuit configuration of the power conversion unit U. Since the other power conversion units U have the same configuration, only the configuration of UW5 will be described here. The power conversion unit UW5 includes an LLC resonant converter LLC and an inverter IN.

  Among these, the LLC resonant converter LLC includes an input side capacitor Ci, a full-bridge inverter circuit 11 composed of semiconductor elements Q1, Q2, Q3, and Q4, an exciting inductance 1, a leakage inductance 2, and a resonant capacitor 3 connected in series. The isolated transformer 12 and the full-bridge rectifier circuit 13 composed of the diodes D1, D2, D3, and D4. After the direct current input from the solar panel PL is converted into a high frequency alternating current, the direct current is again generated. Has been converted.

  The inverter IN is composed of a capacitor C and an inverter circuit 14 having a full bridge configuration including semiconductor elements Q5, Q6, Q7, and Q8. Thus, an AC voltage is generated using the DC voltage Vd1 provided by the LLC resonant converter LLC as a power source. Thus, the power conversion unit UW5 has a configuration in which the input is connected to the direct current from the solar panel PL and the output is connected to the high-voltage system side.

  The power conversion unit UW5 connects the high voltage side terminal TA1 of the AC output terminals TA1 and TA2 to the AC output terminal TA2 of the adjacent high voltage side power conversion unit UW6 and the low voltage side terminal TA2 adjacent to the low voltage side. To the AC output terminal TA1 of the power conversion unit UW4. Thus, the plurality of power conversion units U forming each phase share the high voltage of the power system by connecting the input side in parallel and connecting the output side in series.

  In the power conversion device housing 100, a plurality of power conversion units U configured as illustrated in FIG. 3 are arranged by adopting a three-stage stacked structure for each phase. FIG. 4 also shows an arrangement example of the power conversion unit U in the power conversion device casing 100, but is different from FIG. 3 only in that an AC circuit breaker is provided in each phase on the output side of the power conversion device. doing.

  FIG. 5 shows a configuration of an electric circuit of the power conversion device realized by connecting a plurality of units in the power conversion device casing 100 configured as shown in FIG. 3 or FIG. According to this configuration, the DC input terminals TD1 and TD2 of each power conversion unit U are connected in parallel, and the AC output terminals TA1 and TA2 of each power conversion unit U are connected in series, so that the voltage of the power system For example, the line voltage of 6.6 (kV) is achieved. In this example, each phase shares a line voltage of 6.6 (kV) by eight power conversion units U, so each power conversion unit U outputs a voltage of about 800 (V). It will be. In addition, the control apparatus 100 is controlling the ignition timing with respect to the semiconductor element in the some power conversion unit U of each phase. In addition to the plurality of power conversion units U, the control device 100 can be housed in the power conversion device casing 100 illustrated in FIG.

  A plurality of power conversion units are accommodated in the power conversion device casing 100 of FIG. 1, but the following measures are effective in order to realize the arrangement in a small space.

  First, regarding the miniaturization of the power conversion unit U itself, the power conversion unit U includes an LLC resonant converter LLC and a single-phase inverter IN as main components as shown in FIG. Therefore, when these components are arranged, the lower substrate on which the components constituting the primary circuit of the LLC transformer 12 are mounted on the lower side and the secondary circuit on the upper side are arranged via the LLC transformer 12 and the insulating material. By using the upper substrate on which the components to be mounted are mounted, the low voltage side and the high voltage side are separated, and the height direction of the power conversion unit U is shortened so that the structure suitable for the low-profile power converter housing 100 is obtained. Good. In this configuration, the primary side substrate and the secondary side substrate are supported by a support member, and the LLC transformer 12 is appropriately fixed and arranged between the primary side substrate and the secondary side substrate. The heat generated by the above can be discharged outside using the space formed between the upper and lower primary side substrates and the secondary side substrate.

  Moreover, in FIG. 3, about the several power conversion unit U which forms each phase, arrange | position in the horizontal direction of the power converter device housing | casing 100, and arrange | position to the height direction in three steps | paragraphs for every phase, A gradation configuration is realized by electrically connecting the left and right. Eight units are one phase, and the U, V, and W phases are configured in the vertical direction of the power conversion device casing 100. One side of the power conversion unit U group of each phase is a high-voltage three-phase output to the system, and the opposite side is a neutral point in the Y connection. The neutral point is grounded through a high resistance and becomes a low voltage potential. The insulation distance can be shortened by arranging a DC input from sunlight and a breaker (MCCB) on the neutral point side. As shown in FIG. 4, a high-pressure air load switch (LBS) can be disposed on the high-pressure three-phase output side. It is good also as another structure without providing in the housing | casing 100. FIG.

  By adopting the above configuration, a low-profile housing structure that can be installed under the solar panel PL as shown in FIG. 1 can be realized. According to the power conditioning system PCS according to the present invention adopting the configuration of FIG. 1, the power conditioning system PCS having a transformer function that enables boosting and interconnection to a high voltage can be installed in the vicinity of the solar panel PL. Therefore, it is possible to reduce the wiring loss by shortening the DC wiring from the solar panel as compared with the conventional case. Although the high-voltage output wiring is longer than the conventional one, since the high-voltage three-phase output is used, the increase in the high-voltage wiring loss can be suppressed to be sufficiently smaller than the reduction effect of the DC wiring loss.

  Since the power conversion device casing 100 of the present invention shown in FIG. 1 can be installed under a solar panel, cooling against solar radiation that has been required to be considered in a conventional outdoor casing or container can be mitigated.

  In the present invention, since it is installed outdoors, in order to prevent the inside of the power converter housing 100 where the high-voltage terminal is present, a heat exchanger is provided between the housing (inside the housing) and outside the housing (outside the housing). Shorten the insulation distance in the housing by realizing sealing with the outside air in the body.

  FIG. 7 is a diagram showing a mounting relationship between the power conversion device housing 100 and the internal three-phase power conversion unit group 1A. The three-phase power conversion unit group 1A arranged inside the power conversion device casing 100 has a three-stage stacked structure in which the power conversion unit groups 1AU, 1AV, and 1AW of each phase are arranged in the height direction. The three-phase power conversion unit group 1 </ b> A is arranged so as to form a space in the front, rear, left, and right with the power conversion device casing 100 that is an outer shell when housed in the power conversion device casing 100. . The spaces formed at this time are a right space SPR, a left space SPL, a front space SPF, and a rear space SPB with respect to the longitudinal direction. The upper space and the lower space may be appropriately formed.

  FIG. 8 is an overhead view of these spaces from the top of the power conversion device housing 100. For example, an upper power conversion unit group 1AW arranged in three stages in the height direction is arranged at the center of the power conversion device casing 100. A heat radiating fan 21 is disposed in the right space SPR and the left space SPL, which are left and right spaces in the longitudinal direction of the power conversion device casing 100, and discharges the overheated internal air in the power conversion device casing 100. The front space SPF in front is used as a maintenance space, for example. 6 is a door shown on the front side of FIG. 6, and when the front door installed on the lower side of FIG. 8 is opened, the power conversion units U of each phase stacked in multiple stages can be confirmed, and can be removed and attached. Is possible. The rear space SPB is a unit heat exchanging unit that exchanges heat from the power conversion unit U.

  As shown in the figure, the power conversion unit group 1AW is arranged along the longitudinal direction of the power conversion device casing 100. The longitudinal direction of each power conversion unit U is the longitudinal direction of the power conversion unit group 1AW. Eight units are arranged in the intersecting direction. In order from the left in the drawing, UWI, UW2, UW3, UW4, UW5, UW6, UW7, and UW8.

  FIG. 9 shows a perspective view of the power conversion unit U. FIG. Although the power conversion unit UW5 is illustrated here, it is composed of a substrate part 71 and a transformer part 72 sequentially from the front space SPF side in front, and a heat exchanging part 73 is sequentially arranged on the transformer part 72 side. The heat exchanging unit 73 is accommodated in the rear space SPB.

  When the arrangement of the power conversion unit UW5 in FIG. 9 is compared with the circuit of the power conversion unit UW5 in FIG. 3, the transformer section 72 in FIG. 9 houses the primary and secondary windings that constitute the insulating transformer 12 in FIG. The upper board portion 71U of the board portion 71 is a base housing on which electronic components (capacitor Ci, semiconductor elements Q1, Q2, Q3, Q4, etc.) corresponding to the primary circuit of the insulating transformer 12 are mounted. The lower substrate portion 71L includes a base housing on which electronic components (diodes D1, D2, D3, D4, capacitors C, semiconductor elements Q5, Q6, Q7, Q8, etc.) corresponding to the secondary circuit of the insulating transformer 12 are mounted. It is.

  FIG. 10 is a view of the arrangement of the power conversion unit UW5 of FIG. 9 as viewed from the heat exchange unit 73 side. The heat exchanging unit 73 is a heat pipe fin as illustrated in FIG. 10, and a box-shaped heat pipe fin composed of the heat pipe 24 and the fin 21 is arranged along the longitudinal direction of the power converter housing 100. Has been. FIG. 10 shows a configuration in which three stages are stacked.

  8, 9, and 10, the substrate unit 71 and the transformer unit 72 are thermally connected to the heat exchange unit 73 via an aluminum plate or the like. Further, the front side of FIG. 10 corresponds to the front side of FIG. 1, and therefore the heat pipe fins are exposed to the outside air. Therefore, the heat generated in the board portion 71 and the transformer portion 72 is transferred to the heat exchanging portion 73 by thermal connection, exposed to the outside air at the heat pipe fin portion, and the introduced outside air that has been overheated is shown in FIG. The left space SPL or the left space SPR is reached via the unit heat exchange section formed in the side space SPB, and is forcedly discharged to the outside by the fan 21 provided in the left space SPL or the left space SPR. In addition, the transformer part 72 may be provided with an appropriate space so that the outside air from the heat exchange part 73 can be ventilated to the substrate part 71 side.

  As described above, in the present invention, since it can be installed under the solar panel, it is possible to alleviate the cooling against the solar radiation that had to be considered in the conventional outdoor housing or container. Since it is installed in the same way as before, the heat exchange part between the inside and outside of the housing is provided to prevent the inside of the housing where the high-voltage terminal exists, as mentioned above, and the outside air inside the housing is sealed. By doing so, the insulation distance in the housing can be shortened.

  The present invention having the above-mentioned cooling structure inside the case and the flow of wind inside the case is a structure in which the heat exchange part thermally connected to the power conversion unit is arranged on the back of the case, and the cooling inside the case suitable for the low profile type It is a structure. Outside air is taken in from the back of the housing and is introduced into the heat exchanging unit 73 of the power conversion unit. Exhaust air after passing through the heat exchanging section is exhausted from the left and right sides of the housing by the fans. Outside air flows into the wind tunnel in which the heat exchanging unit 73 and the fan are mounted, but other than that, it is preferable to have a sealed structure partitioned from the outside air.

  The heat pipe type heat exchanging unit used for each power conversion unit has a structure that is cooled by fins thermally connected by heat pipes from each semiconductor element that is a heat source. Although it is assumed that each of the primary side and the secondary side of the transformer has heat pipe fins, the fin interval of either one of the fins may be narrower than that of another fin, and there is no problem with pressure loss. If so, it may be the same pitch.

  Also, although any fan is assumed to use an axial fan, a centrifugal fan that can tolerate a larger pressure loss may be used, and any fan that has a similar function may be used. Also, the number of fans shown in the figure may be increased or decreased according to the type of fan described above or the actual application.

  Note that in this structure, the air whose temperature has risen after cooling the unit is directed to the heat pipe fins on the left and right sides of the case, so the back and side of the case also have heat exchange functions with the outside of the case. Cooling can be realized.

  In the first embodiment, the basic items of the power converter configuration of the present invention have been described as representative examples. In the second embodiment, further modifications of the configuration and specifications of the power conversion device will be described.

  The power conversion device according to the present invention is preferably housed in the power conversion device casing 100 and configured as shown in FIGS. 3 and 4, but is further modified and used as follows. It may be.

  First, the example shown in FIGS. 3 and 4 is a configuration in which a single-phase inverter IN is applied to the subsequent stage of a full-bridge type LLC resonant converter LLC whose inputs are connected in parallel, and the single-phase inverter IN is used as a gradation configuration to output a high voltage. is there. As the gradation configuration, a Y-connection type is assumed, and the number of gradation levels is assumed to be eight, but is not limited thereto. The neutral point N of the Y connection may be grounded or high resistance grounded, but is not limited thereto. Moreover, although the high voltage output by 8 step | paragraph structure assumes 6.6kV output, you may make other voltages, such as changing the number of structures.

  Since the DC voltage Vd1 provided by the full-bridge type LLC resonant converter LLC is a DC voltage of 1500 V or less, it is assumed that MOS FETs suitable for high frequency driving are applied as the semiconductor elements Q1, Q2, Q3, and Q4. . The switching frequency is assumed to be several tens kHz to several hundreds kHz. As the MOS FET to be used, a SiC MOS FET suitable for high withstand voltage / high frequency switching may be applied, or other similar functions may be used. The secondary side of the LLC resonant converter LLC is assumed to be a diode rectification and smoothing circuit. In addition to Si diodes, Si-type Schottky barrier diodes and SiC Schottky barrier diodes may be applied to reduce conduction loss, or loss can be reduced by using SiC MOS FETs in synchronization. It is sufficient if it has other similar functions.

  The LLC resonance type isolation transformer 12 has an insulating function with respect to the system voltage, and in order to achieve LLC resonance, a leakage inductance 2 and a resonance capacitor 3 that correspond to the excitation inductance 1 of the high frequency transformer are connected in series. is there. The leakage inductance 2 is assumed to be integrated in the high-frequency transformer as a structure capable of adjusting the constant of the leakage magnetic flux in the high-frequency transformer, but is not limited thereto. The resonant capacitor 3 is assumed to use a film capacitor or a ceramic capacitor, but may have any similar function.

  Unlike the LLC resonant converter LLC, the single-phase inverter IN subsequent to the LLC resonant converter LLC has a low switching frequency but is hard switching. Therefore, a MOS FET having a small switching loss is applied as the semiconductor elements Q5, Q6, Q7, and Q8. Is assumed. As the MOS FET to be used, a SiC MOS FET suitable for high withstand voltage / high frequency switching may be applied, or a high frequency driving IGBT or other similar functions may be used.

  Further, as the third embodiment, various circuit configurations illustrated in FIGS. 11 to 13 can be adopted as the circuit configuration in the power conversion unit U.

  First, regarding the circuit configuration in the power conversion unit U of FIG. 11, this circuit configuration is a 2-in-1 unit circuit configuration that assumes a case where the input current is small, such as when the input voltage is 1500 V rated.

  Here, two primary-side insulating transformers 12 of a full-bridge type LLC resonant converter LLC whose inputs are connected in parallel are arranged in series, and the secondary side of the two insulating transformers 12 is connected in parallel two systems of rectifier circuit 13 and inverter circuit IN. It is what. Specifically, a single-phase inverter is applied to each subsequent stage of the rectifier circuit that receives the output of each isolation transformer, and two single-phase inverters are configured as one unit. According to this circuit configuration, the structural members can be shared, and the unit structure can be reduced in size and weight. In addition, since the primary currents of the two isolation transformers are the same, variations in the power balance for the two stages can be kept small.

  The circuit configuration in the power conversion unit U in FIG. 12 is a configuration in which two single-phase inverters are three-level inverters, and the same effects as in FIG. 11 can be obtained. Further, since the drive frequency of the inverter is 1/10 or less compared to the LLC resonant converter LLC, it is not a SiC MOS FET but a portion of a three-level inverter MOS FET (Q5a, Q6a in FIG. 10) as shown in FIG. , Q7a, Q8a, Q5b, Q6b, Q7b, Q8b) can be IGBTs (H5a, H6a, H7a, H8a, H5b, H6b, H7b, H8b in FIG. 13). Also, a new three-level inverter configuration may be used if the semiconductor element can withstand twice the withstand voltage.

  A connection example of a plurality of power conversion units U in the power conversion apparatus housing 100 when the third embodiment is employed will be described with reference to FIG. In this case, the grayscale configuration is realized by arranging the power conversion units of each phase in the horizontal direction of the casing and electrically connecting the single-phase inverter side on the left and right. For this reason, in the third embodiment in which the 2 in 1 unit is applied, unlike the first embodiment, the power conversion unit 4 series is one phase, and the U, V, and W phases are configured in the height direction of the power conversion device housing 100. In this configuration, the number of power lines connected between unit cells and the number of connections outside the unit such as signal lines can be reduced.

  Further, as a fourth embodiment, a circuit configuration example in the power conversion unit U is shown in FIG. The circuit configuration of FIG. 15 is a unit circuit configuration that assumes a case where the input current is small, such as when the input voltage is rated at 1500V.

  In FIG. 15, the rectifier circuit 13 is duplicated, but the inverter IN is common. In this case, the transformers 12 of the full-bridge type LLC resonant converter LLC, whose inputs are connected in parallel, are arranged in series on the primary side, the rectifier circuits 13 subsequent to the LLC transformers 12 are arranged in parallel, and the inverter IN is shared. Thus, the power output for two transformers is made possible with one unit. According to this configuration, it is possible to increase the capacity, and it is possible to reduce the size and weight per capacity as an effect of increasing the capacity. In addition, since the primary currents of the two transformers are the same, variations in the power balance for the two stages can be kept small.

  Unlike the LLC resonant converter LLC, the single-phase inverter IN subsequent to the LLC resonant converter LLC has a low switching frequency but is hard switching. Therefore, it is assumed that a MOS FET having a small switching loss is applied. As the MOS FET to be used, a SiC MOS FET suitable for high withstand voltage / high frequency switching may be applied, or any IGBT having a high frequency driving IGBT or other similar functions may be applied.

  The casing structure of the power converter casing 100 is assumed to have the same 8-unit configuration as in the first embodiment, but is not limited to this. Although many examples have been described above, the contents described in the examples may be used in combination depending on the application.

1: Excitation inductance 2: Leakage inductance 3: Resonance capacitor 11: Inverter circuit 12: Insulation transformer 13: Rectifier circuit 14: Inverter circuit 21: Radiating fan 71: Board part 72; Transformer part 73: Heat exchange part 100: Power conversion Device housing B, BB: Base C: Capacitor Ci: Input side capacitors D1, D2, D3, D4: Diode IN: Inverter LLC: LLC resonant converter PL: Solar panels Q1, Q2, Q3, Q4, Q5, Q6, Q7, Q8: Semiconductor elements SPR, SPL, SPF, SPB: Space TD1, TD2: DC input terminal TL1, TL2: DC output terminal TA1, TA2: AC output terminal TU, TV, TW: Three-phase AC output terminal U: Power Conversion unit

Claims (11)

For a power conversion unit comprising a single-phase inverter on the secondary side of a high-frequency resonant converter whose input is DC and comprising a high-frequency transformer and components connected to the primary and secondary windings, a plurality of power The output of the single-phase inverter of the conversion unit is connected in series to form a power conversion unit group, and each AC phase is formed by three sets of the power conversion unit group housed in a power conversion device casing,
The plurality of power conversion units constituting the power conversion unit group are arranged along the longitudinal direction of the power conversion device casing, and three sets of the power conversion unit groups are arranged at a height of the power conversion device casing. Placed in the upper, middle and lower tiers,
One end side in the longitudinal direction of the power conversion device casing serves as an output terminal of the three sets of power conversion unit groups, and three sets of power conversion unit groups on the other end side in the longitudinal direction of the power conversion device casings Are connected in common,
Each of the plurality of power conversion units transmits heat generated by components connected to the high-frequency transformer and its primary winding and secondary winding side to the respective heat radiating portions,
The heat dissipating parts of the plurality of power conversion units are aligned and arranged in a heat exchanging space formed on the back side, which is one surface having an opening, along the longitudinal direction of the power conversion device casing, A power conversion device that discharges superheated air introduced from the opening through a fan provided in the left and right quality in the longitudinal direction of the power conversion device casing that communicates with a space for heat exchange. The power conversion device according to claim 1,
A power converter having a DC circuit breaker on a DC input side of the power conversion unit. The power conversion device according to claim 1,
A power converter having a high-pressure air load switch on an output terminal side of the power conversion unit group. The power conversion device according to claim 1,
The high-frequency resonant converter includes a resonant transformer, and the primary side of two sets of resonant transformers are connected in series. The power conversion device according to claim 4,
A power conversion device characterized in that a single-phase inverter is provided on each secondary side of the two sets of resonant transformers, and gradation connection for two stages is made. The power conversion device according to claim 4,
A power conversion device comprising a series connection at a subsequent stage of diode rectification of the secondary side of the resonant transformer, and a three-level inverter at the subsequent stage. The power conversion device according to claim 4,
A power conversion device characterized in that subsequent stages of diode rectification of the secondary side of the resonant transformer are connected in parallel. The power conversion device according to claim 1,
The power converter device has a low-profile structure that can be placed in the shade of a solar panel that is installed at a photovoltaic power generation site and supported by a gantry. The power conversion device according to claim 1,
The power conversion unit mounts the high-frequency transformer, a first substrate on which a component connected to the primary winding side of the high-frequency transformer is mounted, and a component connected to the secondary winding side of the high-frequency transformer. A power conversion device comprising a second substrate and the heat radiating portion. The power conversion device according to claim 1,
In the power conversion unit, the first substrate and the second substrate are respectively disposed above and below one end of the high-frequency transformer, and the heat dissipating unit is disposed on the other end of the high-frequency transformer. A power conversion device. The power conversion device according to claim 1,
The heat dissipation unit of the power conversion unit is a heat pipe fin provided with a fin structure connected to a heat pipe.

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