JPWO2020059880A1 - AC voltage output system, power system control system, power system, DC power transmission system, power generation system and battery system - Google Patents

Abstract

It provides an AC voltage output system, a power system control system, a power system, a DC power transmission system, a power generation system, and a battery system that can be continuously operated even when the power supply for driving the switch is lost. The AC voltage output system of the present invention includes at least one arm in which a plurality of unit converters 3 for outputting a predetermined voltage are connected in series, and the unit converter 3 includes a first switch 13H and a second switch 13L. The first switch arm 13 includes a first switch arm 13 connected in series, a second switch arm 14 in which a third switch 14H and a fourth switch 14L are connected in series, and a power storage 15 capable of charging and discharging. The 1st switch 13H side end of 13 and the 3rd switch 14H side end of the 2nd switch arm 14 are connected, and the 2nd switch 13L side end of the 1st switch arm 13 and the 4th of the 2nd switch arm 14 are connected. The first switch arm 13, the second switch arm 14, and the power storage 15 are connected in parallel to the switch 14L side end, and the first switch 13H, the third switch 14H, and the second switch are connected in parallel. The 13L and the fourth switch 14L or the first switch 13H, the third switch 14H, the second switch 13L and the fourth switch 14L are composed of normally-on type switching elements.

Description

The present invention relates to an AC voltage output system, a power system control system, a power system, a DC power transmission system, a power generation system and a battery system.

As a power storage system capable of highly efficient power conversion, a plurality of unit converters configured by connecting a switch circuit (power conversion circuit) and a DC power supply (power storage device) are connected in series, and each unit converter A multiplexed inverter type power storage system configured to synthesize and output the output voltage of a power supply circuit is known (see Patent Document 1).

In the power storage system disclosed in Patent Document 1, since a plurality of unit converters are connected in series, the control device fails, the power supply for driving the switch fails, or the power supply line is cut off. If the power supply for driving the switch of one unit converter is lost and the unit converter cannot operate, the other unit converters must also stop operating and the power storage system must be stopped. ..

In a system in which a plurality of unit converters are connected in series, such as the power storage system disclosed in Patent Document 1, the system is continued even when the power supply of one of the plurality of unit converters is lost. As a method for operating, Patent Document 2 discloses that a short-circuit switch is provided in each unit converter, and when the unit converter loses power, the short-circuit switch is turned on to short-circuit the unit converter that has lost power. (See Patent Document 2).

Japanese Unexamined Patent Publication No. 2006-174663 Japanese Unexamined Patent Publication No. 2011-193615

However, in the conventional power storage system, in order to continuously operate the AC voltage output system when the power supply for driving the switch is lost, it is necessary to provide a short-circuit switch in the unit converter and short-circuit the unit converter in which the power supply is lost. there were. Due to the large size of the short circuit switch, the size of the AC voltage output system also increases. In addition, the cost is increased by providing the short-circuit switch. Therefore, there is a demand for an AC voltage output system that does not require a short-circuit switch and can be continuously operated even when the power supply for driving the switch is lost.

Therefore, the present invention has been made in view of the above problems, and is capable of continuous operation even when the power supply for driving the switch is lost, such as an AC voltage output system, a power system control system, a power system, and a DC power transmission system. , A power generation system and a battery system are intended to be provided.

The AC voltage output system according to the present invention includes at least one arm in which a plurality of unit converters that output a predetermined voltage are connected in series, and the unit converter connects the first switch and the second switch in series. The first switch arm, the second switch arm in which the third switch and the fourth switch are connected in series, and a power storage capable of charging and discharging are provided, and the first switch side end of the first switch arm is provided. The unit and the third switch side end of the second switch arm are connected, and the second switch side end of the first switch arm and the fourth switch side end of the second switch arm are connected. The first switch arm, the second switch arm, and the power storage device are connected in parallel to each other, and the first switch and the third switch, the second switch and the fourth switch, or the above. The first switch, the third switch, the second switch, and the fourth switch are composed of normally-on type switching elements.

The AC voltage output system according to the present invention includes at least one arm in which a plurality of unit converters that output a predetermined voltage are connected in series, and the unit converter connects the first switch and the second switch in series. The first switch arm, the second switch arm in which the third switch and the fourth switch are connected in series, and a power storage capable of charging and discharging are provided, and the first switch side end of the first switch arm is provided. The unit and the third switch side end of the second switch arm are connected, and the second switch side end of the first switch arm and the fourth switch side end of the second switch arm are connected. The first switch arm, the second switch arm, and the power reservoir are connected in parallel, and the first switch and the third switch, the second switch and the fourth switch, or the fourth switch are configured. The first switch, the third switch, the second switch, and the fourth switch are composed of switching elements using field-effect transistors in which a low on-voltage is realized by two-dimensional electronic gas.

The AC voltage output system according to the present invention includes at least one arm in which a plurality of unit converters that output a predetermined voltage are connected in series, and the unit converter connects the first switch and the second switch in series. The first switch arm, the second switch arm in which the third switch and the fourth switch are connected in series, and a power storage capable of charging and discharging are provided, and the first switch side end of the first switch arm is provided. The unit and the third switch side end of the second switch arm are connected, and the second switch side end of the first switch arm and the fourth switch side end of the second switch arm are connected. The first switch arm, the second switch arm, and the power storage device are connected in parallel to each other, and the first switch and the third switch, the second switch and the fourth switch, or the above. The first switch, the third switch, the second switch, and the fourth switch are composed of a switching element using a field effect transistor made of gallium nitride.

The AC voltage output system according to the present invention includes at least one arm in which a plurality of unit converters that output a predetermined voltage are connected in series, and the unit converter connects the first switch and the second switch in series. The first switch arm, the second switch arm in which the third switch and the fourth switch are connected in series, and the power storage capable of charging and discharging are provided, and the first switch side end of the first switch arm is provided. The unit and the third switch side end of the second switch arm are connected, and the second switch side end of the first switch arm and the fourth switch side end of the second switch arm are connected. The first switch arm, the second switch arm, and the power storage device are connected in parallel, and the first switch and the third switch, the second switch and the fourth switch, or the above. The first switch, the third switch, the second switch, and the fourth switch are composed of switching elements using a field-effect transistor made of gallium nitride, and the field-effect transistor is formed on silicon. It is formed.

The power system control system according to the present invention includes a system control device for controlling an AC power distribution system or a power system to which an AC power transmission system is connected, and the system control device is based on the frequency of the AC power distribution system or the AC power transmission system. The output of any of the above AC voltage output systems connected to the AC distribution system or the AC power transmission system is controlled.

The power system according to the present invention is a power system to which an AC distribution system or an AC transmission system is connected, and any of the above AC voltage output systems is connected to the AC distribution system or the AC transmission system to generate the AC power. The output of the AC voltage output system is controlled based on the frequency of the system or the AC transmission system.

The power system control system according to the present invention includes a system control device for controlling an AC power distribution system or a power system to which an AC power transmission system is connected, and the power system includes a plurality of the AC power distribution systems or a plurality of the AC power transmission systems. One of the above AC voltage output systems is connected to at least one of the plurality of AC distribution systems or the plurality of AC transmission systems, and the system control device is the output of the AC voltage output system. By controlling the above, the power flow of the AC distribution system or the AC transmission system is controlled.

The power system according to the present invention is a power system to which an AC distribution system or an AC transmission system is connected, and a plurality of the AC distribution systems or a plurality of the AC transmission systems are connected in parallel, and the plurality of the AC power distribution systems are connected in parallel. Any one of the above AC voltage output systems is connected to at least one of the system or the plurality of AC transmission systems, and the output of the AC voltage output system controls the power flow of the AC distribution system or the AC transmission system.

The DC transmission system according to the present invention includes any of the above AC voltage output systems, a DC transmission line is connected to the DC terminal, and the DC power input from the DC transmission line to the DC terminal is converted into AC power. And output from the AC terminal.

The power generation system according to the present invention includes any of the above AC voltage output systems, an active power source is connected to the DC terminal, and the DC power input from the active power source to the DC terminal is converted into AC power. Is output from the AC terminal.

The battery system of the present invention comprises any of the above AC voltage output systems.

According to the present invention, when the drive power supply for the switch of the unit converter is lost, the unit converter is in a short-circuited state, so that continuous operation can be performed even when the drive power supply for the switch is lost.

It is a schematic diagram which shows the structure of the AC voltage output system of this invention. It is a schematic diagram which shows the structure of the unit converter of the AC voltage output system of this invention. FIG. 3A is a schematic cross-sectional view showing an example of an FET composed of GaN, and FIG. 3B shows a GaN-FET and a control circuit of a gate driver and a unit converter for driving a Gan-FET on the same silicon substrate. It is a schematic cross-sectional view which shows an example of the case where it is provided. FIG. 4A is a schematic view showing an example of the configuration of a switching element in which a normally-on type switching element is improved to a normally-off type, and FIG. 4B shows a normally-on view of the normally-off type switching element of FIG. 4A. It is a schematic diagram which shows an example of the switching element improved into a mold. It is a schematic diagram which shows the distribution system stabilization apparatus of a modification. It is a schematic diagram which shows the structure of the AC voltage output system of the modification.

(1) Overall Configuration of AC Voltage Output System of the Embodiment of the Present Invention As shown in FIG. 1, the AC voltage output system 1 of the present embodiment is connected to an AC distribution system (hereinafter, simply referred to as a distribution system) 510. It is used as a distribution system stabilizing device that receives and receives electric power and stabilizes the distribution system 510. In this case, the AC voltage output system 1 is connected to the distribution line of the distribution system 510 between the power system 50 and the load 56. The power system 50 is integrated into a circuit symbol indicating a voltage source, but there may be various system configurations. For example, it may be a system whose frequency changes depending on the relationship between power supply and demand, similar to a domestic power system. If the input of mechanical energy or light energy to a generator (not shown) is larger than the output of the generator, the frequency will be higher, and if it is lower, the frequency will be lower. Further, unlike the above, a system in which only a generator is connected via a power converter is also one of the examples of the power system 50. The AC voltage output system 1 includes an R-phase arm 2R, an S-phase arm 2S, and a T-phase arm 2T as arms. The R-phase arm 2R, the S-phase arm 2S, and the T-phase arm 2T each include four unit converters 3 that output a predetermined voltage, and four unit converters 3 are connected in series. One end of the R-phase arm 2R, the S-phase arm 2S, and the T-phase arm 2T is connected to the terminals 53u, 53v, 53w of the distribution lines 57u, 57v, 57w of the distribution system 510 via the reactors 150R, 150S, 150T, respectively. The other end is star-connected at the connection point NP. As described above, the R-phase arm 2R, the S-phase arm 2S, and the T-phase arm 2T are connected in parallel between the connection point NP and the distribution system 510.

As shown in FIG. 2, in the unit converter 3, the first switch arm 13 in which the first switch 13H and the second switch 13L are connected in series, and the third switch 14H and the fourth switch 14L are connected in series. It is provided with a second switch arm 14 and a power storage device 15 capable of charging and discharging. The power storage 15 is composed of a secondary battery such as a lithium ion battery, a nickel hydrogen battery, and a nickel cadmium battery. The power storage 15 is not particularly limited as long as it can charge and discharge electric power, and may be a capacitor, an electric double layer capacitor, a DC flywheel, or the like.

As described above, since the AC voltage output system 1 includes a power storage device 15 in which each unit converter 3 can charge and discharge electric power, electric energy can be stored by charging each power storage device 15. It can be used as a power storage device.

The unit converter 3 includes an end of the first switch arm 13 on the first switch 13H side, an end of the second switch arm 14 on the third switch 14H side, and one terminal of the power storage 15 (in the present embodiment). The positive side) is connected, the end of the first switch arm 13 on the second switch 13L side, the end of the second switch arm 14 on the fourth switch 14L side, and other terminals of the power storage 15 (the present embodiment). Then, the minus side) is connected. As described above, the unit converter 3 has a full bridge circuit configuration in which the first switch arm 13, the second switch arm 14, and the power storage device 15 are connected in parallel.

A control circuit (not shown) is connected to the unit converter 3, and a drive voltage (for example,) that controls on / off of each switch is controlled to the first switch 13H, the second switch 13L, the third switch 14H, and the fourth switch 14L. , (Gate voltage in the case of a switching element composed of FET (field effect transistor)) is supplied.

In the unit converter 3, the first terminal FT is pulled out from the connection point 10 between the first switch 13H and the second switch 13L of the first switch arm 13, and the third switch 14H and the fourth switch 14L of the second switch arm 14 are drawn out. The second terminal ST is pulled out from the connection point 12 with. Assuming that the voltage of the power storage device 15 is V, the unit converter 3 switches on / off the first switch 13H, the second switch 13L, the third switch 14H, and the fourth switch 14L to obtain the first terminal FT. It is possible to output three levels of voltage, ± V and zero, between the second terminal ST and the terminal ST. It should be noted that each unit converter 3 may be configured to output the same voltage, and different voltages may be output by appropriately changing the configuration (battery capacity, etc.) of the power storage 15 of each unit converter 3. It may be configured to do so.

In the AC voltage output system 1 shown in FIG. 1, the first terminal FT of one unit converter 3 and the second terminal ST of another unit converter 3 are connected, and a plurality of unit converters 3 are connected in series. It is connected. Therefore, the AC voltage output system 1 responds to the number of unit converters 3 by switching the number of unit converters 3 that output voltage in the R-phase arm 2R, S-phase arm 2S, and T-phase arm 2T, respectively. Each arm can output a multi-step voltage. Further, the AC voltage output system 1 includes a control device that controls the control circuit of each unit converter 3. The control device sends a command to the control circuit of each unit converter for the control circuit to control the on / off of the switch of each unit converter, and the R-phase arm 2R, the S-phase arm 2S, and the T-phase arm 2T. Outputs multi-step AC voltage from. In the present embodiment, the case where the R-phase arm 2R, the S-phase arm 2S, and the T-phase arm 2T each include four unit converters 3 has been described, but the number of unit converters 3 included in each arm has been described. Is not limited. If the number of unit converters 3 provided in each arm is large, the number of stages of AC voltage output by the AC voltage output system 1 will be large, and the waveform of the AC voltage will be closer to a sine wave even if the switching frequency of each switching element is low. It can be made into a waveform. Therefore, the switching loss of the semiconductor can be reduced. Further, since a voltage waveform close to a sine wave can be output, there is an advantage that the harmonic filter can be deleted or simplified. Furthermore, since high voltage can be output by using multiple stages, there is an advantage that the buck-boost transformer can be omitted depending on the system.

In the unit converter 3, since the first switch arm 13 and the second switch arm 14 are connected in parallel, the first switch 13H and the third switch are between the first terminal FT and the second terminal ST. 14H is connected in series (reverse series), and the second switch 13L and the fourth switch 14L are connected in series. Here, one of the switches (first switch 13H and third switch 14H) connected in series between the first terminal FT and the second terminal ST is defined as the first switch group 16, and the other of the switches connected in series (the other) (1st switch group 16). The second switch 13L and the fourth switch 14L) are designated as the second switch group 17.

The unit converter 3 includes each switch of the first switch group 16 (first switch 13H and third switch 14H), each switch of the second switch group 17 (second switch 13L and fourth switch 14L), or the first switch group. Each switch (first switch, third switch, second switch, and fourth switch) of 16 and the second switch group 17 is composed of a normally-on type switching element. Here, the normally-on type switching element referred to in the present specification refers to a switching element in which the switch is in the on state when the drive voltage for controlling the on / off of the switch is zero. The normally-off type switching element is a switching element in which the switch is in the off state when the drive voltage is zero, and is generally used as a switch in the field of power electronics, for example, metal oxidation formed of silicon. Object Semiconductor FET (Si-HPLC), Insulated-gate bipolar transistor (IGBT), Gate Turn-Off thyristor (GTO), Gate Commutated Turn-off thyristor: GCT) and so on.

In the present embodiment, in the unit converter 3, each switch of the first switch group 16 is composed of an IGBT in which each switch of the first switch group 16 is a normally-off type switching element, and each switch of the second switch group 17 is a normally-on type switching element. It is composed of a high electron mobility transistor (hereinafter, also referred to as HEMT). Further, in the present embodiment, an FET (hereinafter, also referred to as GaN-FET) composed of GaN (gallium nitride) is used as the HEMT. This GaN-FET is, for example, a GaN-FET formed on a Si substrate on Si (silicon). The HEMT is a field-effect transistor that uses a high-mobility two-dimensional electron gas induced in a semiconductor heterojunction as a channel and realizes a lower on-voltage than a normal FET that is turned on by applying a voltage to the gate. .. Since the HEMT has a low on-voltage, it can reduce power consumption by switching the switch on and off, and since it is a high-voltage FET, it is connected to a distribution system of about 100V to 6.6kV or a higher voltage transmission system. Suitable for AC voltage output system 1. In particular, the GaN-FET has a lower switching loss than Si in the high voltage region, and is therefore more suitable for the AC voltage output system 1 that handles high voltage. Further, in the case of the present embodiment, since the GaN-FET is formed on the Si substrate, it can be manufactured at a lower cost than the case where the GaN-FET is formed on the GaN substrate, which is further preferable. As a switching element using a field-effect transistor that realizes a low on-voltage by two-dimensional electron gas, a normally-on depletion mode MOS-FET can also be used.

The configuration of the GaN-FET used in this embodiment will be described. As shown in FIG. 3A, the GaN-FET 20 is formed on the Si substrate 21. The GaN-FET 20 includes a GaN layer 22 formed on the Si substrate 21, an AlGaN layer 23 formed in contact with the GaN layer 22, a source electrode 24 formed in contact with the AlGaN layer 23, a drain electrode 25, and a gate. It includes an insulating layer 27 and a gate electrode 26 formed in contact with the gate insulating layer 27. In the GaN-FET 20, a two-dimensional electron gas layer is formed at the interface between the AlGaN layer 23 and the GaN layer 22, and the two-dimensional electron gas layer serves as a conductive channel. Therefore, even if the voltage applied to the gate electrode 26 is zero, the source electrode 24 -It is possible to pass a current between the drain electrodes 25. Therefore, the switching element composed of the GaN-FET 20 is in the ON state even when the drive voltage applied to the gate electrode 26 is zero, and is a normally-on type. In the switching element composed of the GaN-FET 20, by applying a negative drive voltage to the gate electrode 26, no current flows between the source electrode 24 and the drain electrode 25, and the switch can be turned off.

Further, as shown in FIG. 3B, as the switching element composed of the GaN-FET 20, the gate driver 28 for driving the GaN-FET 20 and the control circuit of the unit converter 3 (first switch 13H, second switch 13L, first switch 13L, first switch 13H, second switch 13L, first switch 13H, second switch 13L, The control circuit) 19 for driving the 3 switch 14H and the 4th switch 14L may be mounted on the same Si substrate 21. Note that FIG. 2 shows the GaN-FET 20 largely for convenience of explanation. Further, the GaN-FET is not limited to the Si substrate, and may be formed on, for example, a SiC substrate or a GaN substrate. Further, in the present embodiment, a GaN-FET switching element formed on a Si substrate is used for the second switch 13L and the fourth switch 14L, and the switching element for the second switch 13L and the switching element for the fourth switch 14L are used. Is a separate body. However, the switching elements for the second switch 13L and the fourth switch 14L may be integrally formed, for example, a GaN-FET for the second switch 13L and a GaN for the fourth switch 14L on one Si substrate. -The one in which the FET is formed may be used. Further, the first switch 13H and the third switch 14H may also be formed integrally with the second switch 13L and the fourth switch 14L (on the same substrate).

As described above, in the unit converter 3, each switch of the first switch group 16 is a normally-off type switching element, and each switch of the second switch group 17 is a normally-on type switching element. The power supply for driving the switch for supplying the drive voltage to the 1 switch 13H, the 2nd switch 13L, the 3rd switch 14H and the 4th switch 14L fails, or the control circuit itself of the unit converter 3 fails. When the power supply for driving each switch (switching element) of the unit converter 3 is lost due to the disconnection of the power supply line, the drive voltage of each switch becomes zero, and the first switch 13H and the third switch 14H is turned off, and the second switch 13L and the fourth switch 14L are turned on. That is, a short-circuit path is formed from the second terminal ST to the fourth switch 14L, the second switch 13L, and the first terminal FT via this order. Therefore, the unit converter 3 is in a state in which the first terminal FT and the second terminal ST are short-circuited.

In the prior art of a converter having a configuration in which unit converters are connected in series, all switches of the unit converter are composed of normally-off type switching elements, so that when the power supply for driving the switches is lost, All switches were turned off, the first terminal and the second terminal were isolated, no current flowed to the unit converter and the arm to which the unit converter belongs, and the operation had to be stopped. .. Therefore, the conventional AC voltage output system requires a short-circuit switch for short-circuiting between the first terminal and the second terminal.

On the other hand, in the AC voltage output system 1 of the present embodiment, when the drive power supply for each switch of the unit converter 3 is lost, the unit between the first terminal FT and the second terminal ST is short-circuited, and the unit conversion is performed. Since the device 3 is in a short-circuited state and a current flows between the first terminal FT and the second terminal ST, the current does not stop flowing to the arm to which the unit converter belongs, and continuous operation can be performed. Further, in the AC voltage output system 1, since the first terminal FT and the second terminal ST are short-circuited, the unit converter 3 is short-circuited between the first terminal FT and the second terminal ST. There is no need to provide a switch. The unit converter 3 is a switch of the first switch group 16 (first switch 13H and a third switch 14H) or each switch of the first switch group 16 and the second switch group 17 (first switch 13H, third switch 14H). , 2nd switch 13L and 4th switch 14L) have the same effect even if they are composed of normally-on type switching elements.

When each switch of the first switch group 16 is a normally-on type switching element and each switch of the second switch group 17 is a normally-off type switching element, each switch (switching element) of the unit converter 3 is used. When the drive power supply is lost, the drive voltage of each switch becomes zero, the first switch 13H and the third switch 14H are turned on, and the second switch 13L and the fourth switch 14L are turned off. That is, a short-circuit path is formed from the second terminal ST to the first switch 13H, the third switch 14H, and the first terminal FT in this order. Therefore, the unit converter 3 is in a state in which the first terminal FT and the second terminal ST are short-circuited.

Further, when each switch (first switch 13H, third switch 14H, second switch 13L and fourth switch 14L) of the first switch group 16 and the second switch group 17 is a normally-on type switching element, the unit is When the drive power supply for each switch (switching element) of the converter 3 is lost, the drive voltage of each switch becomes zero and all the switches are turned on. As a result, a short-circuit route from the second terminal ST to the first terminal FT via the first switch 13H and the third switch 14H in this order, and from the second terminal ST to the second switch 13L and the fourth switch 14L. A short-circuit path to the first terminal FT via the order is formed, and the first terminal FT and the second terminal ST are short-circuited.

As described above, in the AC voltage output system 1, the unit converter 3 is a switch of each of the first switch group 16 (first switch 13H and third switch 14H) or each of the first switch group 16 and the second switch group 17. Even if the switches (1st switch 13H, 3rd switch 14H, 2nd switch 13L and 4th switch 14L) are composed of normally-on type switching elements, the power supply for driving each switch of the unit converter 3 is lost. At that time, the first terminal FT and the second terminal ST are short-circuited, and the unit converter 3 is short-circuited. Then, in the AC voltage output system 1, a current flows between the first terminal FT and the second terminal ST of the unit converter 3 for which the drive power supply has been lost, so that the current flows to the arm to which the unit converter 3 belongs. It can be operated continuously without disappearing.

Next, the effect when the AC voltage output system 1 as the distribution system stabilizing device is used as the frequency stabilizing device for stabilizing the frequency of the distribution system 510 will be described. As shown in FIG. 1, the AC voltage output system 1 is connected to the distribution system 510. The distribution system 510 connects the power system 50 and the load 56 with distribution lines 57u, 57v, 57w, and supplies power from the power system 50 to the load 56. Here, as in the domestic power system, the power system 50 has a higher frequency if the input of mechanical energy or optical energy to the generator (not shown) is larger than the output of the generator, and the frequency is lower if the input is lower than the generator output. It is assumed that the system is low. One end of the distribution line 57u is connected to the u phase of the power system 50, and the other end is connected to the R phase of the load 56. One end of the distribution line 57v is connected to the v phase of the power system 50, and the other end is connected to the S phase of the load 56. One end of the distribution line 57w is connected to the w phase of the power system 50, and the other end is connected to the T phase of the load 56. Here, the power system 50 includes power generation equipment such as a generator, power transmission equipment such as an AC power transmission system, substation equipment such as a transformer, distribution equipment such as an AC distribution system, and consumer equipment such as a load. It is a power transmission and distribution network, and is controlled by a power system control system (not shown in FIG. 1) provided in a command center or the like. The distribution system 510 and the load 56 are connected to such a power system 50.

Further, the distribution line 57u has a terminal 53u, and the R phase arm 2R of the AC voltage output system 1 is connected to the terminal 53u. The distribution line 57v has a terminal 53v, and the S-phase arm 2S of the AC voltage output system 1 is connected to the terminal 53v. The distribution line 57w has a terminal 53w, and the T-phase arm 2T of the AC voltage output system 1 is connected to the terminal 53w. In this way, the AC voltage output system 1 is connected to the distribution system 510. The load 56 is, for example, a consumer such as a factory or a machine or a manufacturing apparatus owned by the consumer. Further, 52u, 52v, 52w and 51u, 51v, 51w in FIG. 1 schematically represent reactoron components and resistance components of the distribution lines 57u, 57v, 57w on the power system 50 side from the terminals 53u, 53v, 53w. 54u, 54v, 54w and 55u, 55v, 55w schematically represent the reactor and resistance components of the distribution lines 57u, 57v, 57w on the load 56 side of the terminals 53u, 53v, 53w. ..

The AC voltage output system 1 as a distribution system stabilizing device can stabilize the frequency of the distribution system 510. For example, a control device (not shown in FIG. 1) receives a detection result of a three-phase batch or a frequency of each phase from a frequency measuring device (not shown in FIG. 1) provided in the distribution system 510, and distributes power. Monitor the frequency of system 510. Since a normal three-phase power system receives power from a three-phase generator, the frequency of each phase is the same. Here, considering that it is physically possible to connect only a single-phase generator to each phase, there may be a rather insane assumption that the frequencies of each phase are not necessarily the same. I will explain on the premise. If the frequency of each phase is different, another serious problem such as the phase order is changed, but we will focus on the frequency only. When the control device detects that the frequency of one of the phases has increased, it absorbs power from the phase (distribution line) with the increased frequency, and when it detects that the frequency of one of the phases has decreased. The unit converter 3 of the R-phase arm 2R, the S-phase arm 2S, and the T-phase arm 2T is controlled so as to discharge power to the phase whose frequency has decreased. For example, when the frequency of the u-phase of the distribution system 510 becomes high, the control device controls each switch of the unit converter 3 of the R-phase arm 2R so that the power storage 15 is charged by the voltage of the u-phase. It absorbs power from the u phase and lowers the frequency of the u phase. Further, when the frequency of the u phase of the distribution system 510 is lowered, the control device controls each switch of the unit converter 3 of the R phase arm 2R so that the power storage device 15 discharges to the u phase. Power is discharged from the arm 2R to the u phase to raise the frequency of the u phase. As described above, the distribution system stabilizing device using the AC voltage output system 1 can stabilize the frequency of the distribution system 510.

The frequency of the distribution system 510 fluctuates due to the imbalance of power supply and demand in the event of a system accident due to a lightning strike or the like, and in an extreme case, a generator (not shown) of the power system 50 is out of step. Normally, the AC voltage output system 1 prevents such a situation, but a lightning strike or the like tends to damage the AC voltage output system 1, and the drive power supply for each switch of the unit converter 3 is used. It may be lost. If the AC voltage output system 1 is according to the present invention, the operation can be continued even when the drive power supply is partially lost, so that the robustness against frequency fluctuation and generator step-out can be improved.

Here, the control device of the AC voltage output system 1 controls the output to the distribution system 510 for each phase based on the frequency of each phase of the distribution system 510 to which the AC voltage output system 1 is connected, and distributes power. It has been described that the frequency of each phase of the system 510 is stabilized. However, the present invention is not limited to this, and the system control device (not shown in FIG. 1) of the above power system control system that controls the power system 50 to which the distribution system 510 is connected is a phase of each phase of the distribution system 510. Control may be performed to stabilize the frequency. In this case, the system control device controls the output of the AC voltage output system 1 connected to the distribution system 510 for each phase based on the frequency of each phase of the distribution system 510, and determines the frequency of each phase of the distribution system 510. Stabilize. Since the frequency stabilization control method is the same as that of the control device of the AC voltage output system 1, the description thereof will be omitted.

Next, the effect when the AC voltage output system 1 as the distribution system stabilizing device is used as the power adjustment device between the phases of the distribution system 510 will be described. For example, the power required for the u-phase, v-phase, and w-phase of the distribution system 510 so that the u-phase is insufficient in power with respect to the power demand of the load 56 and the w-phase is in excess of power with respect to the power demand of the load 56. When is unbalanced, the control device controls the switch of each unit converter 3 of the S phase arm 2S so as to charge the power storage 15 of the unit converter 3 with the voltage of the w phase from the w phase. Absorbs power to eliminate excess power. Then, the control device controls the switch of each unit converter 3 of the R-phase arm 2R so that the power storage device 15 discharges to the u-phase, and the R-phase arm 2R releases power to the u-phase to cause a power shortage. To eliminate. In this way, the distribution system stabilizer supplies power to the u phase with insufficient power, absorbs power from the w phase with excess power, adjusts the imbalance of power between the phases, and stabilizes the distribution system 510. Can be transformed into.

The distribution system stabilizer can also balance the line voltage between the distribution lines 57u, 57w, 57v of the distribution system 510. For example, a control device (not shown in FIG. 1) monitors the voltage of each phase of the distribution system 510. When the control device detects the imbalance of the line voltage from the voltage of each phase, the AC voltage output system 1 outputs a high voltage to the phase where the voltage is high and outputs a low voltage to the phase where the voltage is low. The unit converter 3 of the R-phase arm 2R, the S-phase arm 2S, and the T-phase arm 2T is controlled so as to do so. For example, when the w-phase voltage of the distribution system 510 is high and the u-phase voltage of the distribution system 510 is low, the control device controls the switch of each unit converter 3 of the R-phase arm 2R and the S-phase arm 2S. A high voltage is output to the u phase, a low voltage is output to the w phase, and the line voltage between the distribution line 57u and the distribution line 57w is balanced. In this way, the distribution system stabilizing device can balance the line voltage between the distribution lines 57u, 57w, 57v of the distribution system 510 and stabilize the distribution system 510.

It should be noted that the influence of a lightning strike differs between the phases of the distribution system 510, and a ground fault or the like occurs only in a specific phase, causing an imbalance in the interphase voltage even when the load is dropped. Further, due to the influence of the lightning strike, the driving power supply of the corresponding phase of the AC voltage output system 1 may be lost at the same time. If the AC voltage output system 1 is according to the present invention, the operation can be continued even when the drive power supply is partially lost, so that the robustness against frequency fluctuation and generator step-out can be improved.

From the above, the distribution system stabilizer using the AC voltage output system 1 can control the frequency of each phase, adjust the excess or deficiency of power between the phases, and eliminate the imbalance of the voltage between the phases. The distribution system 510 can be stabilized. Further, since the distribution system stabilizer is provided with the AC voltage output system 1, it can be continuously operated even when the power supply for driving the switch of the unit converter 3 of the AC voltage output system 1 is lost, and is more reliable. .. The AC voltage output system 1 can be applied as a stabilizer of the AC power transmission system by connecting to the AC power transmission system connecting the power systems instead of the AC power distribution system 510. Further, although the AC voltage output system 1 is for three-phase AC, it is also possible to remove one arm and use it for single-phase. Further, it can be used for single phase by removing the two arms and connecting the remaining one arm between the single phase terminals of the interconnection point.

(2) Actions and effects In the above configuration, the AC voltage output system 1 has at least one arm (R-phase arm 2R, S-phase arm 2S) in which a plurality of unit converters 3 for outputting a predetermined voltage are connected in series. , T-phase arm 2T), the unit converter 3 has a first switch arm 13 in which a first switch 13H and a second switch 13L are connected in series, and a third switch 14H and a fourth switch 14L in series. A connected second switch arm 14 and a power storage 15 capable of charging and discharging are provided, and a first switch 13H side end of the first switch arm 13 and a third switch 14H side end of the second switch arm 14 are provided. Connected, the second switch 13L side end of the first switch arm 13 and the fourth switch 14L side end of the second switch arm 14 are connected, and the first switch arm 13, the second switch arm 14, and the power storage are connected. The device 15 is connected in parallel, and the first switch 13H and the third switch 14H, the second switch 13L and the fourth switch 14L or the first switch 13H, the third switch 14H, the second switch 13L and the fourth switch 14L is configured to be composed of a normally-on type switching element.

Therefore, in the AC voltage output system 1 of the present invention, when the power supply for driving the switch of the unit converter 3 is lost, the first terminal FT and the second terminal ST are short-circuited, and the unit converter 3 is short-circuited. Since it is in a short-circuited state, continuous operation can be performed even when the power supply for driving the switch is lost. Therefore, the AC voltage output system 1 can omit the short-circuit switch.
Furthermore, if the unit converter 3 is housed in one case together with a control means for measuring the SOC (state of charge) and SOH (state of health) of the battery, it functions as a battery pack with a built-in converter, so that the battery Can be replaced smoothly when the battery deteriorates.
Further, when the DC voltage of the unit converter 3 is as low as about 30 V or less, a plurality of unit converters 3 may be built in one case having a low explosion-proof function. When the DC voltage is low, the first switch 13H and the second switch 13L of the unit converter 3 are erroneously turned on, and even if a PN short circuit occurs, the voltage is low, so the risk of explosion of the switching element is sufficiently low, and the explosion-proof function. Can be built in one low case.
Further, if each case is provided with a concave portion and a convex portion so that the convex portion of another case can be inserted into the concave portion of one case, it becomes easy to connect a large number of battery packs in multiple stages. In particular, it is still preferable that one unit converter 3 and another unit converter 3 can be electrically connected by the insertion.

(3) Modifications The present invention is not limited to the above embodiment, and various modifications can be made within the scope of the gist of the present invention. In the above embodiment, HEMT, which is a normally-on type switching element, is used as a first switch 13H and a third switch 14H, a second switch 13L and a fourth switch 14L or a first switch 13H, a second switch 13L, and a third switch. It has been described that it is used for the switch 14H and the fourth switch 14L (see FIG. 2). In reality, normally-on type switching elements such as HEMTs are often marketed as normally-off type switching elements to which a circuit for normalizing off is added.

Such a normally-off type switching element (hereinafter referred to as an N-OFF switching element for convenience of explanation) is also referred to as an N-OFF switching element when a circuit described later is added and the drive power supply is lost. By making it normally-on, it can be used as a normally-on type switching element for the switches (first switch, second switch, third switch, fourth switch) of the above embodiment. Hereinafter, an example of a circuit of the N-OFF switching element and an example of a circuit for turning on the N-OFF switching element normally will be described.

FIG. 4A is a diagram showing an example of an N-OFF switching element. In the N-OFF switching element 30 shown in FIG. 4A, a normally-on type switching element 29 (for example, a GaN-FET which is a HEMT) and a normally-off type switching element 31 (for example, Si-PWM) are cascoded. It has a connected configuration. In FIG. 4A, S is a source-side terminal of the N-OFF switching element 30, and D is a drain-side terminal of the N-OFF switching element 30. The normally-on type switching element 29 is arranged on the drain terminal D side, and the normally-off type switching element 31 is arranged on the source side. The gate 29G of the normally-on type switching element 29 is connected to the wiring on the source side of the normally-off type switching element 31. The gate 31G of the normally-off type switching element 31 is connected to a control circuit of the N-OFF switching element 30 (not shown in FIG. 4A), and a drive voltage for driving the normally-off type switching element 31 is applied. , Is applied to the gate 31G from the control circuit.

In the N-OFF switching element 30, when a positive drive voltage is applied to the gate 31G from the control circuit, the normally-off type switching element 31 is turned on, and the normally-on type switching element 29 is connected to the gate 29G. Since the applied voltage becomes equal to the source voltage of the switching element 29, the switching element 29 is turned on.

On the other hand, when the drive voltage is not applied to the gate 31G from the control circuit, the normally-off type switching element 31 is turned off. At this time, since the gate voltage of the normally-on type switching element 29 is lower than the source voltage of the normally-on type switching element 29, the normally-on type switching element 29 is also turned off. As a result, the N-OFF switching element 30 is turned off because no current can flow between the source terminal S and the drain terminal D. In this way, the N-OFF switching element 30 cascodes the normally-on type switching element 29 and the normally-off type switching element 30 to make the normally-on type switching element 29 normally off. There is.

Refer to FIG. 4B for one method of the present invention in which the N-OFF switching element 30, which is a switching element obtained by normally turning off the normally-on type switching element 29, is turned on normally when the drive power supply is lost. I will explain. Here, for convenience of explanation, a switching element obtained by normally turning on the N-OFF switching element 30 is referred to as an N-ON switching element.

As shown in FIG. 4B, the N-ON switching element 37 includes a normally-on type switching element 29 and a normally-off type switching element 31 (to the N-OFF switching element 30 shown in FIG. 4A) connected in series. It includes a resistor 32, a Zener diode 33, and a switching element 34 for supplying a drive voltage. The resistor 32 is inserted between the gate 31G of the normally-off type switching element 31 and the drain terminal D. The Zener diode 33 is inserted between the gate 31G and the source terminal S, the anode is connected to the source terminal S side, and the cathode is connected to the gate 31G side. In the present embodiment, the gate 31G, the resistor 32, and the Zener diode 33 are connected at the connection point 35. The specifications of the resistor 32 and the Zener diode 33 are appropriately set according to the threshold voltage of the normally-off type switching element 31 and the like.

Further, the drain of the driving voltage supply switching element 34 is connected to the connection point 35. The drive voltage supply switching element 34 is connected to a control circuit (not shown in FIG. 4B) of the N-ON switching element 37 that supplies the drive voltage of the normally-off type switching element 31 to the source. The drive voltage supply switching element 34 is provided to cut off the control circuit and the connection point 35 when the power supply is lost. In the drive voltage supply switching element 34, the gate 34G is normally in the ON state. The drive voltage supply switching element 34 is connected to the power supply circuit of the control circuit of the N-ON switching element 37. When the drive voltage supply switching element 34 is in the ON state, the gate 34G can be driven by the control circuit.

On the other hand, when the drive power supply of the N-ON switching element 37 is lost, the drive voltage supply switching element 34 is turned off and the connection point 35 is cut off from the control circuit. As a result, the voltage at the connection point 35 rises to the voltage allowed by the Zener diode 33. Since the increased voltage of the connection point 35 is applied to the gate 31G of the switching element 31 and higher than the drive voltage of the switching element 31, the switching element 31 is turned on. As a result, the N-ON switching element 37 is turned on. In this way, the N-ON switching element 37 is turned on when the drive power supply is lost and the drive voltage is no longer supplied. Therefore, even if the N-ON switching element 37 is used as a normally-on type switching element in the switch of the unit converter 3 of the above embodiment, the same effect as that of the above embodiment can be obtained.

In the above embodiment, a GaN-FET formed on a Si substrate as a normally-on type switching element on the second switch 13L and the fourth switch 14L of the unit converter 3 shown in FIG. 2 (see FIG. 3A). Was used to explain the case of using. At this time, as the normally-on type switching element, a GaN-FET for the second switch 13L and a GaN-FET for the fourth switch 14L may be integrally formed on one Si substrate. I also explained that. Further, in the present invention, for example, a GaN-FET for the second switch 13L and a GaN-FET for the fourth switch 14L are formed on a Si substrate in which the control circuit of the unit converter 3 is mounted on Si. It may be used as a marie-on type switching element. Other circuits mounted on the Si substrate include, for example, a circuit corresponding to a control device that controls the control circuit of each unit converter 3 of the AC voltage output system 1, and a circuit corresponding to a gate driver. When the first switch 13H and the third switch 14H are normally-on type switching elements, the GaN-FET for the first switch 13H and the third switch 14H are on the Si substrate on which the circuit is formed. GaN-FET and. Further, a normally-off type switching element used for a switch other than a switch using a normally-on type switching element may also be formed on a circuit-formed Si substrate. Each switch of the unit converter 3 such as the control circuit of the unit converter 3, the circuit corresponding to the control device that controls the control circuit of each unit converter 3 of the AC voltage output system 1, and the circuit corresponding to the gate driver. All the elements and all the switches constituting the circuit for driving at least one of the switch 13H, the second switch 13L, the third switch 14H and the fourth switch 14L) may be mounted on Si, and some of them may be mounted on Si. Only the element may be mounted on Si.

In the above embodiment, the case where the AC voltage output system 1 is used for three-phase AC as shown in FIG. 1 has been described, but the present invention is not limited to this, and one arm of the AC voltage output system is used. It can also be used for single-phase alternating current.

Further, in the above embodiment, as shown in FIG. 1, the case where the AC voltage output system 1 is applied as the distribution system stabilizing device of the distribution system between the power system and the load has been described. Not limited to. For example, as shown in FIG. 5, the AC voltage output system 1 can be used for power flow control of distribution systems 510 and 610 connected in parallel between the power system 50 and the power system 59. In the example shown in FIG. 5, the power system 50 and the power system 59 are connected by the distribution system 510 and the distribution system 610. Both ends of the distribution system 610 are connected to the distribution system 510, and the distribution system 510 and the distribution system 610 are connected in parallel. The AC voltage output system 1 is connected to terminals 53u, 53v, 53w of each phase of the distribution system 510. A load (not shown in FIG. 5) is connected to each of the distribution system 510 and the distribution system 610.

Even in such a case, the distribution system stabilizer controls the frequency of each phase, adjusts the excess or deficiency of power between the phases, and the voltage between the phases, similarly to the distribution system stabilizer shown in FIG. You can eliminate the imbalance of. Further, the distribution system stabilizing device can eliminate the imbalance in the power flow between the power system 50 and the power system 59 in the distribution system 510 and the distribution system 610. For example, when the power flow of the distribution system 510 is excessive, the voltage of the distribution system 510 charges the power storage 15 of the unit converter 3 of the R-phase arm 2R, the S-phase arm 2S, and the T-phase arm 2T, and the distribution system 510. By absorbing the electric power of, the tidal current is reduced.

On the other hand, when the power flow of the distribution system 510 is insufficient (when the power required for the load (not shown in FIG. 5) cannot be supplied), the unit conversion of the R-phase arm 2R, the S-phase arm 2S, and the T-phase arm 2T is performed. The power flow is increased by discharging the power storage 15 of the device 3 to supply power to the distribution system 510. In addition, the power flow can be increased by increasing the output voltage (voltage at the interconnection point).

In this way, the AC voltage output system 1 that transfers power to and from the distribution system 510 can eliminate the excess or deficiency of the power flow of the distribution system. Further, the distribution system stabilizer using the AC voltage output system 1 can be continuously operated even when the drive power supply for the switch of the unit converter 3 of the AC voltage output system 1 is lost, and is more reliable. The AC voltage output system 1 may be connected to the distribution system 610 instead of the distribution system 510. A plurality of AC voltage output systems 1 may be prepared, and the AC voltage output system 1 may be connected to both the distribution system 510 and the distribution system 610, respectively.

Here, the case where the control device of the AC voltage output system 1 connected to one of a plurality of distribution systems 510 and 610 (distribution system 510) connected in parallel controls the power flow of the distribution system 510 and the distribution system 610. As described above, the present invention is not limited to this. The system control device of the power system control system that controls the power system 50, the power system 59, or both to which the distribution system 510 is connected controls the output of the AC voltage output system 1 connected to the plurality of distribution systems 510, and distributes power. The system 510 and the distribution system 610 may be controlled. Since the power flow control method is the same as the case where the control device of the AC voltage output system 1 controls the power flow, the description thereof will be omitted. The AC voltage output system 1 can be applied as a stabilizer of the AC power transmission system by connecting to the AC power transmission system connecting the power systems instead of the distribution system 510.

(4) Other Applications of AC Voltage Output System The AC voltage output system 1 of the present invention has a power storage device 15 in which each unit converter 3 can charge and discharge power, and stores power at a predetermined timing. Since the stored electric power can be output as an AC voltage, it is used for various battery systems such as UPS (non-disruptive power supply device) and electric vehicle batteries, and converters for DC transmission, in addition to the distribution system stabilizer. be able to.

The AC voltage output system 1 can also be used as a UPS. For example, as shown in FIG. 1, the AC voltage output system 1 is connected to a commercial AC power supply and has a power receiving unit that receives power from the commercial AC power supply, a power storage unit that stores the power received by the power receiving unit, and a power storage unit. It is equipped with a power supply unit that supplies the stored electric power to electrical and electronic equipment. The AC voltage output system is used as the power storage unit and functions as a UPS. The AC voltage output system 1 functioning as the UPS charges the power storage of each unit converter of the AC voltage output system with the power from the commercial AC power supply, and outputs the AC voltage when the commercial AC power supply is cut off. Outputs AC voltage and supplies AC voltage to electrical and electronic equipment via the power supply unit. Since the UPS includes the AC voltage output system of the present invention, it can be continuously operated even when the power supply for driving the switch of the unit converter 3 of the AC voltage output system is lost, and the reliability is higher.

When used for a battery of an electric vehicle, the AC voltage output system 1 is connected to each phase of a three-phase AC motor instead of the power system 50 shown in FIG. Further, it is preferable to use a large-capacity secondary battery for the power storage 15 of each unit converter 3. Further, terminals for charging the power storage device 15 from the outside of the electric vehicle are connected to each arm of the AC voltage output system 1. In the battery provided with the AC voltage output system 1, the power storage 15 is charged by an external power supply, and the power stored in the AC voltage output system 1 is converted into an AC voltage by the AC voltage output system 1 for three phases. It is supplied to each phase of the AC motor to rotate the motor. At this time, the power storage 15 of the AC voltage output system 1 can also be charged by the voltage regenerated by the motor. Since the battery of a conventional electric vehicle is a secondary battery such as a lithium ion battery, an inverter that converts the DC voltage output by the secondary battery into an AC voltage is required. On the other hand, by using the AC voltage output system 1 as the battery of the electric vehicle, the battery and the inverter can be replaced with the AC voltage output system 1 and these configurations can be omitted. Further, since the battery of the electric vehicle is provided with the AC voltage output system 1, it can be continuously operated even when the power supply for driving the switch of the unit converter 3 of the AC voltage output system 1 of the present invention is lost, and the reliability is higher. high. The AC voltage output system 1 can also be applied to batteries of automobiles other than electric automobiles.

In the AC voltage output system 1 shown in FIG. 1, one end of the R-phase arm 2R, the S-phase arm 2S, and the T-phase arm 2T is star-connected, and the other end is connected to each phase of the distribution system via the reactors 150R, 150S, and 150T. Although it was a form connected to, the mode of the AC voltage output system can be changed in various ways. For example, as in the AC voltage output system 110 shown in FIG. 6, the leg 110R (also referred to as an R-phase leg) in which two arms 112R are connected in series, and the leg 110S (S-phase) in which two arms 112S are connected in series. An AC voltage output system in which a leg (also called a leg) and a leg 110T (also called a T-phase leg) in which two arms 112T are connected in series are connected in parallel with one end connected to each other and the other end connected to each other. It may be 110.

The arms 112R, 112S, 112T (also referred to as R-phase arm, S-phase arm, and T-phase arm) of the AC voltage output system 110 shown in FIG. 6 have three unit converters 3 and a reactor 103, and a reactor 103 at an end. It is connected in series so that it comes to. In the example shown in FIG. 6, the configurations of the arms 112R, 112S, and 112T are the same. In each leg 110R, 110S, 110T, the reactor 103s of the arms 112R, 112S, 112T are connected to each other and connected in series. Each leg 110R, 110S, 110T is provided with DC terminals P1 and N1 for transmitting and receiving DC power at both ends, and is provided with AC terminals 113R, 113S, and 113T for transmitting and receiving AC power to the connection points between the arms, respectively. ing. In the AC voltage output system 110, the legs 110R, 110S, and 110T share one DC terminal P1 and N1 because their ends are connected to each other.

The AC terminals 113R, 113S, and 113T are connected to the u-phase, v-phase, and w-phase of the power system 50, respectively. Therefore, the AC voltage output system 110 has a configuration in which the legs 110R, 110S, and 110T are star-connected by the DC terminal P1 and the DC terminal N1. The unit converter 3 of each arm 112R, 112S, 112T is the unit converter 3 shown in FIG. 2, and has a full bridge circuit configuration.

The AC voltage output system 110 connects, for example, an active power source 105 such as a prime mover, a solar power generation device, or a wind power generation device between the DC terminal P1 of each leg 110R, 110S, 110T and the DC terminal N1. It can be used in a power generation system that converts DC power generated by a prime mover into multi-stage AC power according to the number of unit converters 3 and outputs it to each phase of the power system 50. Further, the AC voltage output system 110 converts the DC power input from the DC transmission line into multi-stage AC power by connecting the DC transmission line to the DC terminal P1 and the DC terminal N1, and each phase of the power system 50. It can be used for DC transmission systems that output to. On the contrary, in this DC transmission system, the AC voltage output system 110 can also convert the AC power input from the power system 50 into DC power and output it to the DC transmission line for DC transmission. Although it is publicly known information, when the unit converter 3 has a full bridge configuration, there is an advantage that the DC output voltage can be lowered and the short-circuit current can be suppressed in the event of a DC short-circuit accident due to a lightning strike or the like.

Such an AC voltage output system 110 includes at least one arm (arms 112R, 112S, 112T) in which a plurality of unit converters 3 for outputting a predetermined voltage are connected in series, and the unit converter 3 is the first. A first switch arm 13 in which a switch 13H and a second switch 13L are connected in series, a second switch arm 14 in which a third switch 14H and a fourth switch 14L are connected in series, and a power storage device capable of charging and discharging. 15 is provided, the first switch 13H side end of the first switch arm 13 and the third switch 14H side end of the second switch arm 14 are connected, and the second switch 13L side end of the first switch arm 13 is connected. And the end of the 4th switch 14L of the 2nd switch arm 14 are connected, and the 1st switch arm 13, the 2nd switch arm 14 and the power storage 15 are connected in parallel, and the 1st switch 13H The third switch 14H, the second switch 13L and the fourth switch 14L or the first switch 13H, the third switch 14H, the second switch 13L and the fourth switch 14L are composed of normally-on type switching elements.

The effect of the AC voltage output system 110 will be described. For example, when a lightning strike occurs, the AC voltage output system 110 may lose the power source for driving the switch of the unit converter 3. However, the AC voltage output system 110 is in a state of being short-circuited when the drive power supply for the switch of the unit converter 3 is lost, so that the AC voltage output system 110 is continuously operated even when the drive power supply for the switch is lost. can do. Therefore, the AC voltage output system 110 can omit the short-circuit switch.

The AC voltage output system 110 shown in FIG. 6 is for three-phase AC, but can be used for single-phase by removing two legs. Further, the number of unit converters 3 possessed by each arm 112R, 112S, 112T is not limited. In this example, the AC voltage output system 110 is connected to the power system 50, but may be connected to an AC distribution system or a DC distribution system connected to the power system.

1 AC voltage output system 2R R phase arm 2S S phase arm 2T T phase arm 3 Unit converter 13 1st switch arm 13H 1st switch 13L 2nd switch 14 2nd switch arm 14H 3rd switch 14L 4th switch 15 Power storage Instrument 20 GaN-FET

Claims (17)

It is equipped with at least one arm in which multiple unit converters that output a predetermined voltage are connected in series.
The unit converter
The first switch arm in which the first switch and the second switch are connected in series, and
A second switch arm in which the third switch and the fourth switch are connected in series, and
Equipped with a power storage that can be charged and discharged
The first switch side end of the first switch arm and the third switch side end of the second switch arm are connected, and the second switch side end of the first switch arm and the second switch. The fourth switch side end of the arm is connected, and the first switch arm, the second switch arm, and the power storage device are connected in parallel.
The first switch and the third switch, the second switch and the fourth switch or the first switch, the third switch, the second switch and the fourth switch are composed of normally-on type switching elements. AC voltage output system. It is equipped with at least one arm in which multiple unit converters that output a predetermined voltage are connected in series.
The unit converter
The first switch arm in which the first switch and the second switch are connected in series, and
A second switch arm in which the third switch and the fourth switch are connected in series, and
Equipped with a power storage that can be charged and discharged
The first switch side end of the first switch arm and the third switch side end of the second switch arm are connected, and the second switch side end of the first switch arm and the second switch. The fourth switch side end of the arm is connected, and the first switch arm, the second switch arm, and the power storage device are connected in parallel.
The first switch and the third switch, the second switch and the fourth switch or the first switch, the third switch, the second switch and the fourth switch realize a low on-voltage by two-dimensional electron gas. An AC voltage output system consisting of switching elements that use field-effect transistors. It is equipped with at least one arm in which multiple unit converters that output a predetermined voltage are connected in series.
The unit converter
The first switch arm in which the first switch and the second switch are connected in series, and
A second switch arm in which the third switch and the fourth switch are connected in series, and
Equipped with a power storage that can be charged and discharged
The first switch side end of the first switch arm and the third switch side end of the second switch arm are connected, and the second switch side end of the first switch arm and the second switch. The fourth switch side end of the arm is connected, and the first switch arm, the second switch arm, and the power storage device are connected in parallel.
A field-effect transistor in which the first switch and the third switch, the second switch and the fourth switch or the first switch, the third switch, the second switch and the fourth switch are made of gallium nitride. AC voltage output system consisting of switching elements using. It is equipped with at least one arm in which multiple unit converters that output a predetermined voltage are connected in series.
The unit converter
The first switch arm in which the first switch and the second switch are connected in series, and
A second switch arm in which the third switch and the fourth switch are connected in series, and
Equipped with a power storage that can be charged and discharged
The first switch side end of the first switch arm and the third switch side end of the second switch arm are connected, and the second switch side end of the first switch arm and the second switch. The fourth switch side end of the arm is connected, and the first switch arm, the second switch arm, and the power storage device are connected in parallel.
The first switch and the third switch, the second switch and the fourth switch or the first switch, the third switch, the second switch and the fourth switch are field effect type made of gallium nitride. It is composed of switching elements using transistors, and is composed of switching elements.
An AC voltage output system in which the field effect transistor is formed on silicon. The alternating current according to claim 4, wherein at least a part of the elements of the circuit for driving at least one of the first switch, the second switch, the third switch, or the fourth switch is mounted on the silicon. Voltage output system. The AC voltage output according to any one of claims 2 to 5, which is a normally-off type switching element that becomes normally on when the switching element using the field-effect transistor loses the driving power supply. system. Connected to an AC power distribution system or AC power transmission system,
The AC voltage output according to any one of claims 1 to 6, further comprising a control device for controlling the output to the AC power distribution system or the AC power transmission system based on the frequency of the AC power distribution system or the AC power transmission system. system. Equipped with a system control device that controls the power system to which the AC power distribution system or AC power transmission system is connected.
The AC voltage output according to any one of claims 1 to 6, wherein the system control device is connected to the AC power distribution system or the AC power transmission system based on the frequency of the AC power distribution system or the AC power transmission system. A power system control system that controls the output of the system. An AC power distribution system or a power system to which an AC power transmission system is connected.
The AC voltage output system according to any one of claims 1 to 6 is connected to the AC power distribution system or the AC power transmission system.
A power system in which the output of the AC voltage output system is controlled based on the frequency of the AC distribution system or the AC transmission system. Connected to one of multiple AC distribution systems or multiple AC transmission systems connected in parallel,
The AC voltage output system according to any one of claims 1 to 6, further comprising a control device for controlling the power flow of the AC power distribution system or the AC power transmission system. Equipped with a system control device that controls the power system to which the AC power distribution system or AC power transmission system is connected.
In the power system, a plurality of the AC power distribution systems or a plurality of the AC power transmission systems are connected in parallel.
The AC voltage output system according to any one of claims 1 to 6 is connected to at least one of the plurality of AC power distribution systems or the plurality of AC power transmission systems.
A power system control system in which the system control device controls the output of the AC voltage output system to control the power flow of the AC power distribution system or the AC power transmission system. An AC power distribution system or a power system to which an AC power transmission system is connected.
A plurality of the AC power distribution systems or a plurality of the AC power transmission systems are connected in parallel.
The AC voltage output system according to any one of claims 1 to 6 is connected to at least one of the plurality of AC power distribution systems or the plurality of AC power transmission systems.
A power system in which the power flow of the AC distribution system or the AC transmission system is controlled by the output of the AC voltage output system. With at least one leg in which the two arms are connected in series,
The one according to any one of claims 1 to 6, wherein the leg is provided with DC terminals for transmitting and receiving DC power at both ends, and AC terminals for transmitting and receiving AC power are provided at connection points between the arms. AC voltage output system. The AC voltage output system according to claim 13 is provided.
A DC transmission line is connected to the DC terminal,
A DC transmission system that converts DC power input from the DC transmission line to the DC terminal into AC power and outputs it from the AC terminal. The AC voltage output system according to claim 13 is provided.
An active power source is connected to the DC terminal,
A power generation system that converts DC power input from the active power source to the DC terminal into AC power and outputs it from the AC terminal. A battery system comprising the AC voltage output system according to any one of claims 1 to 6. The battery system according to claim 16, which is a battery for an uninterruptible power supply or an electric vehicle.

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