WO2023149202A1

WO2023149202A1 - Power conversion device

Info

Publication number: WO2023149202A1
Application number: PCT/JP2023/001256
Authority: WO
Inventors: 尊衛嶋田; 公久古川; 玲彦叶田; 雄一馬淵; ナワズフセイン
Original assignee: 株式会社日立製作所
Priority date: 2022-02-02
Filing date: 2023-01-18
Publication date: 2023-08-10
Also published as: JP2023112723A

Abstract

The present invention provides a power conversion device that can be operated appropriately. To enable appropriate operation, a power conversion device (100) comprises a plurality of primary circuits (14) that each convert an input DC voltage to an AC voltage, a plurality of primary transformers (16) that each have a primary winding (16a) connected to one of the plurality of primary circuits (14) and a secondary winding (16b) connected to an AC bus (18), a plurality of secondary transformers (20) that each have a primary winding (20a) connected to the AC bus (18), and a plurality of secondary circuits (22) that convert bidirectionally between secondary winding voltages (Vs1~Vs3) that are voltages in the second windings (20b) of the respective secondary transformers (20) and DC voltages input/output by electrical appliances (131, 132, 133).

Description

power converter

The present invention relates to a power converter.

As a background art of this technical field, the summary of Patent Document 1 below describes "a first inverter unit that obtains a direct current input and provides a high frequency output, an LLC transformer that converts the high frequency output of the first inverter unit into a voltage, Through a rectifier unit that converts the output of the LLC transformer to DC, a second inverter unit that converts the DC output of the rectifier unit to AC, and a power transformer for a control circuit connected in parallel to the secondary circuit of the LLC transformer, It is characterized by comprising a control circuit for obtaining gate power of a semiconductor element that constitutes the second inverter section."

JP 2017-70047 A

By the way, in the technology described above, there is a demand for more appropriate operation of the power converter.
The present invention has been made in view of the circumstances described above, and an object of the present invention is to provide a power converter that can be operated appropriately.

In order to solve the above problems, the power conversion apparatus of the present invention includes a plurality of primary circuits, each of which converts an input DC voltage into an AC voltage, and each of the primary windings is connected to each of the primary circuits. a plurality of primary transformers with secondary windings connected to the AC bus; a plurality of secondary transformers with each primary winding connected to the AC bus; and a voltage at the secondary winding of each of the secondary transformers. and a plurality of secondary circuits for bi-directionally converting the secondary winding voltage and the DC voltage input/output by the electrical equipment.

According to the present invention, it is possible to provide a power converter that can be operated appropriately.

1 is a block diagram of a power converter according to a first embodiment; FIG. It is a circuit diagram of the main part of a power converter. 3 is a waveform diagram of each part in FIG. 2. FIG. It is a schematic diagram which shows the example of the parking lot which installed the power converter device.

[First embodiment]
FIG. 1 is a block diagram of a power converter 100 according to the first embodiment.
The power electronics device 100 is connected between the AC power supply 120 and the power equipment group 130 . Here, the AC power supply 120 is, for example, a high-voltage AC power system of several kilovolts. The power device group 130 includes a plurality of devices that input and output DC power. In the illustrated example, the power equipment group 130 includes an electric vehicle 131 (electrical equipment), a solar power generation device 132 (electrical equipment), and a storage battery system 133 (electrical equipment). The power conversion device 100 bi-directionally converts AC/DC power between the AC power supply 120 and the power equipment group 130 .

The power converter 100 includes a reactor 10, M power converter cells 12-1 to 12-M, M capacitors 13-1 to 13-M, and M primary circuits 14-1 to 14- M, M primary transformers 16-1 to 16-M, a high-frequency bus 18 (AC bus), N secondary transformers 20-1 to 20-N, and N secondary circuits 22-1 22-N, a controller 30, and a clock generator 32. The number M of primary side circuits and the number N of secondary side circuits described above are both plural, and may be the same number or different numbers. Also, in the following description, a plurality of constituent elements, signals, etc. having the same or similar functions and meanings will be denoted by the same reference numerals as “-”, such as “power converter cells 12-1 to 12-M”. and numerical values are sometimes written. However, when there is no need to distinguish between these plurality of constituent elements, they may be indicated by abbreviating "-" and numerical values, such as "power converter cell 12".

The reactor 10 and the power converter cells 12-1 to 12-M are connected in series to the AC power supply 120. Each power converter cell 12 rectifies the applied AC voltage and outputs a DC voltage via capacitor 13 . Each primary circuit 14 converts the DC voltage applied to the corresponding capacitor 13 into a high frequency voltage and applies it to the corresponding primary transformer 16 . Thereby, each primary transformer 16 supplies a high frequency current to the high frequency bus 18 while being insulated from the primary circuit 14 . Here, the high frequency is a frequency of 100 Hz or higher, preferably a frequency of 1 kHz or higher or 10 kHz or higher. Thereby, the power conversion device 100 can be miniaturized.

Each secondary transformer 20 is connected to the high frequency bus 18 . Each secondary circuit 22 bidirectionally converts a high-frequency voltage and a DC voltage, and inputs and outputs DC power to and from the power device group 130 . The high frequency bus 18 comprises a pair of conductors (not numbered), one of which is grounded. By grounding one of the conductors in this way, it is possible to prevent mixed contact between the primary side (high voltage side) and the secondary side (low voltage side). Clock generator 32 supplies clock signals CKP-1 to CKP-M to primary circuits 14-1 to 14-M, respectively, and clock signal CKS to secondary circuits 22-1 to 22-N. -1 to CKS-N, respectively. The controller 30 generates the frequencies and phases of the clock signals CKP-1 to CKP-M and CKS-1 to CKS-N according to the power to be input/output to/from the power device group 130 by the power converter 100. command to the device 32;

FIG. 2 is a circuit diagram of a main part of the power conversion device 100. As shown in FIG.
In FIG. 2, the number M of primary side circuits and the number N of secondary side circuits shown in FIG. 1 are both "3". Each primary circuit 14 comprises four switching elements (not labeled) and four diodes (not labeled) connected anti-parallel to them. Although not shown, each primary circuit 14 includes a drive circuit for driving each switching element based on the supplied clock signal CKP (see FIG. 1).

Capacitors 13-1 to 13-3 are connected in parallel to the primary circuits 14-1 to 14-3. The DC powers input to the primary circuits 14-1 to 14-3 via these capacitors 13-1 to 13-3 are called Pp1 to Pp3. The primary circuits 14-1 to 14-3 are connected to primary windings 16a of primary transformers 16-1 to 16-3. Voltages appearing in the primary windings 16a of the primary transformers 16-1 to 16-3 are called Vp1 to Vp3. 2 may be the internal inductance of the primary transformer 16 or the secondary transformer 20, or may be an external reactor. may A secondary winding 16b of the primary transformer 16 and a primary winding 20a of the secondary transformer 20 are connected in parallel to the high frequency bus 18 .

The voltages appearing in the secondary windings 20b of the secondary transformers 20-1 to 20-3 are called secondary winding voltages Vs1 to Vs3. The secondary windings 20b of these secondary transformers 20 are connected to secondary circuits 22-1 to 22-3. Each secondary circuit 22 includes four switching elements (not labeled) and four diodes (not labeled) connected in anti-parallel to these. Although not shown, the secondary circuit 22 includes a drive circuit that drives each switching element based on the supplied clock signal CKS (see FIG. 1).

Capacitors 24-1 to 24-3 are connected in parallel to the secondary circuits 22-1 to 22-3, respectively. They are called Ps1 to Ps3. Here, in order to simplify the explanation, the terminal voltage of each capacitor 13 and the terminal voltage of each capacitor 24 are assumed to be equal, and the winding ratios of each primary transformer 16 and each secondary transformer 20 are also assumed to be equal.

FIG. 3 is a waveform diagram of each part in FIG.
In FIG. 3, the voltages Vp1 to Vp3 are all square-wave voltages of the same phase having a duty ratio of 50%, and as shown, the rising timings are t10 and t20. As a result, the DC powers Pp1 to Pp3 (see FIG. 2) become equal. Secondary winding voltages Vs1 to Vs3 are also square-wave voltages having a duty ratio of 50%. However, the phase of the secondary winding voltage Vs1 lags behind the phases of the voltages Vp1 to Vp3, the voltage Vs2 has the same phase, and the voltage Vs3 leads. In this case, the DC power Ps1 shown in FIG. 2 has a positive value, and power is supplied from the secondary circuit 22-1 to the power device group 130. FIG.

Also, the DC power Ps2 becomes a negative value, and power is supplied from the power device group 130 to the secondary circuit 22-2. The absolute value of this DC power Ps2 is equivalent to DC powers Pp1-Pp3. Further, the DC power Ps3 also becomes a negative value, and power is supplied from the power device group 130 to the secondary circuit 22-3. However, the absolute value of DC power Ps3 is larger than the absolute value of DC power Ps2. Thus, in the phase relationship of each voltage shown in FIG. 3, the power converter 100 supplies power to the power device group 130 via the secondary circuit 22-1, The power is supplied from the power device group 130 via the . Also, power is supplied from the port with the more advanced phase to the port with the more delayed phase.

As the phase of the voltage Vs2 is gradually delayed from the phase shown in FIG. 3, the absolute value of the DC power Ps2 gradually decreases and eventually becomes zero. As the phase of voltage Vs2 is further delayed, the polarity of DC power Ps2 becomes positive. That is, power is supplied to the power device group 130 from the secondary circuit 22-2. Further, when the phase of voltage Vs2 is further delayed, DC power Ps2 increases. Thus, by adjusting the phases of the secondary winding voltages Vs1 to Vs3 with the clock signal CKS (see FIG. 1), it is possible to adjust the power input to and output from each secondary circuit 22. FIG. It is also possible to output the power supplied from the secondary circuit 22 from the power equipment group 130 to the AC power supply 120 .

The terminal voltage of each capacitor 13 and the terminal voltage of each capacitor 24 may be different voltages, and the winding ratios of each primary transformer 16 and each secondary transformer 20 may be different. In this case, even if voltages Vs1-Vs3 and Vp1-Vp3 have the same phase, DC powers Pp1-Pp3 and Ps1-Ps3 have different values. However, even in this case, if the phases of the secondary winding voltages Vs1 to Vs3 are advanced, the power changes in the direction of input from the power device group 130 to the power conversion device 100, and the secondary winding voltages Vs1 to Vs3 When the phase is delayed, the power changes in the direction of input from the power conversion device 100 to the power device group 130 . Thereby, desired power can be input/output from each secondary circuit 22 to/from the power device group 130 .

FIG. 4 is a schematic diagram showing an example of a parking lot in which the power converter 100 is installed.
In FIG. 4, the parking lot 200 has a ceiling 210 and a floor 220 . The electric vehicle 131 described above has a power receiving connector 131 a and is parked on the floor 220 of the parking lot 200 . The power conversion device 100 includes a substantially flat plate-shaped housing 106 along the shape of the ceiling 210 and is attached to the ceiling 210 of the parking lot 200 .

A cable 102 is attached to the power conversion device 100, and the cable 102 hangs downward. A power supply connector 104 is attached to the lower end of the cable 102 . When the user fits the power supply connector 104 to the power receiving connector 131a and performs a predetermined operation, power is supplied from the power converter 100 to the electric vehicle 131, and the battery (not shown) of the electric vehicle 131 is charged. By mounting the power converter 100 on the ceiling 210 of the parking lot 200 in this way, the power converter 100 can be easily installed in the existing parking lot 200 .

[Comparative example]
Next, a comparative example will be described in order to clarify the effects of the above-described embodiment.
Although illustration of the configuration of the comparative example is omitted, the configuration of the above embodiment shown in FIG. is similar to that of That is, in the comparative example, the DC power Ppk input/output to/from the primary circuit 14-k (1≤k≤M) is equal to the DC power Psk input/output from the secondary circuit 22-k.

According to the configuration of the comparative example, it is possible to simultaneously output DC power from a plurality of secondary circuits 22 to a plurality of electric vehicles 131 and the like. However, since the power converter cell 12 is connected in series with the AC power supply 120, it is difficult to make a large difference between the DC powers input and output by the secondary circuits 22. FIG. Therefore, it is also difficult for a certain secondary circuit 22 to output power to the power device group 130 while another secondary circuit 22 receives power from the power device group 130 . Thus, in the comparative example, there is a problem that the constraint on the power supply and demand state between the power conversion device 100 and the power device group 130 is increased.

[Effects of Embodiment]
As described above, the power converter 100 according to the above-described embodiment includes a plurality of primary circuits 14 each converting an input DC voltage into an AC voltage, and each primary winding 16a connected to each primary circuit 14. a plurality of primary transformers 16 each having a secondary winding 16b connected to the AC bus (18), a plurality of secondary transformers 20 each having a primary winding 20a connected to the AC bus (18); A plurality of secondary winding voltages Vs1 to Vs3, which are voltages in the secondary winding 20b of the secondary transformer 20, and DC voltages input and output by the electrical equipment (131, 132, 133) in both directions. and a secondary circuit 22 . As a result, the electric devices (131, 132, 133) can independently input and output power to and from the power conversion device 100, so that the power conversion device 100 can be operated appropriately.

The power conversion device 100 further includes a plurality of power converter cells 12 connected in series with the AC power supply 120, each of which converts an input AC voltage into a DC voltage and applies the DC voltage to the corresponding primary circuit 14. More preferred. Thereby, the power electronics device 100 can receive power from the AC power supply 120 or supply power to the AC power supply 120 .

Further, it is more preferable that the plurality of secondary circuits 22 set the phases of the respective secondary winding voltages Vs1 to Vs3 in synchronization with the clock signal CKS supplied thereto. As a result, in synchronization with the clock signal CKS, power input/output control corresponding to the corresponding electric devices (131, 132, 133) can be executed.

Further, it is more preferable that the power conversion device 100 further includes a clock generator 32 that sets the phase of the corresponding clock signal CKS according to the power to be input/output by the electrical equipment (131, 132, 133). As a result, more flexible power input/output control can be executed according to the corresponding electrical equipment (131, 132, 133).

Further, it is more preferable that the AC bus (18) comprises a pair of conductors, one of the pair of conductors being grounded. This can prevent mixed contact between the primary side (high pressure side) and the secondary side (low pressure side).

Further, it is more preferable that the power conversion device 100 further includes a housing 106 attached to the ceiling 210 of the parking lot 200 . Thereby, the power conversion device 100 can be easily installed in the existing parking lot 200 .

[Modification]
The present invention is not limited to the embodiments described above, and various modifications are possible. The above-described embodiments are exemplified for easy understanding of the present invention, and are not necessarily limited to those having all the described configurations. Further, other configurations may be added to the configurations of the above embodiments, and part of the configurations may be replaced with other configurations. Also, the control lines and information lines shown in the drawings are those considered to be necessary for explanation, and do not necessarily show all the control lines and information lines necessary on the product. In practice, it may be considered that almost all configurations are interconnected. Possible modifications to the above embodiment are, for example, the following.

(1) In the above embodiment, the power converter 100 inputs and outputs power between the AC power supply 120 such as an AC power system and the power equipment group 130 . However, in recent years, a DC power system has also become popular, so instead of the AC power supply 120, the power converter 100 may be connected to a DC power supply such as a DC power system. In this case, the reactor 10, the power converter cells 12 and the capacitor 13 are not required, so it is preferable to connect the power converter cells 12-1 to 12-M in series with the DC power supply.

12 Power converter cell 14 Primary circuit 16 Primary transformer 16a Primary winding 16b Secondary winding 18 High frequency bus (AC bus)
20 secondary transformer 20a primary winding 20b secondary winding 22 secondary circuit 32 clock generator 100 power converter 106 housing 120 AC power supply 131 electric vehicle (electrical equipment)
132 Photovoltaic equipment (electrical equipment)
133 Storage Battery Systems (Electrical Equipment)
200 Parking lot 210 Ceiling CKS Clock signals Vs1 to Vs3 Secondary winding voltage

Claims

a plurality of primary circuits, each of which converts an input DC voltage to an AC voltage;
a plurality of primary transformers each having a primary winding connected to each said primary circuit and each secondary winding being connected to an AC bus;
a plurality of secondary transformers each having a primary winding connected to the AC bus;
A plurality of secondary circuits for bi-directionally converting a secondary winding voltage, which is a voltage in the secondary winding of each of the secondary transformers, and a DC voltage input/output by an electrical device. and power conversion equipment.
2. The system of claim 1, further comprising a plurality of power converter cells connected in series with an AC power source, each power converter cell converting an input AC voltage to a DC voltage for application to a corresponding said primary circuit. Power converter.
3. The power converter according to claim 2, wherein the plurality of secondary circuits set the phase of each of the secondary winding voltages in synchronization with the clock signal supplied to each.
4. The power converter according to claim 3, further comprising a clock generator that sets the phase of the corresponding clock signal according to the power to be input/output by the electrical equipment.
5. The power converter according to claim 4, wherein said AC bus comprises a pair of conductors, one of said pair of conductors being grounded.
The power converter according to claim 5, further comprising a housing mounted on a ceiling of a parking lot.