POWER CONVERSION DEVICE AND PROGRAM

Abstract

A power conversion device (10) comprises: a first upper-arm switch (S1H), a first sub-arm switch (S1L), a second upper-arm switch (S2H), a second sub-arm switch (S2L), a third upper-arm switch (S3H), a third sub-arm switch (S3L), an upper-arm rectifier (S4H, D4H), a sub-arm rectifier (S4L, D4L), first to third reactors (31 to 33), a connecting line (44), a single-phase charging switch (45) installed in the connecting line, first to third capacitors (161 to 163), a connecting switch (151), and a control unit (70).When the control unit determines that the single-phase AC power source is connected to the first AC terminal and the fourth AC terminal, the control unit closes the single-phase charging switch and opens the connection switch, and performs switching control of the first upper-branch switch and the first lower-branch switch to convert power between the first AC terminal and the fourth AC terminal and the high-voltage DC terminal and the low-voltage DC terminal.

Description

[0001] This application is based on Japanese Patent Application No. 2022-175108 filed on October 31, 2022, which is hereby incorporated by reference. TECHNICAL FIELD

[0002] This disclosure relates to a power conversion apparatus and a program. STATE OF THE ART

[0003] Patent Document 1 discloses a power conversion device that can be connected to a three-phase AC power source. The power conversion device includes series-connected elements for the three phases, each of which includes an upper-branch switch and a lower-branch switch. A high-voltage terminal of each of the upper-branch switches is electrically connected to a high-voltage DC terminal, and a low-voltage terminal of each of the lower-branch switches is electrically connected to a low-voltage DC terminal.The upper branch switch of a first phase is referred to as a first upper branch switch, the sub-branch switch of the first phase is referred to as a first sub-branch switch, the upper branch switch of a second phase is referred to as a second upper branch switch, the sub-branch switch of the second phase is referred to as a second sub-branch switch, the upper branch switch of a third phase is referred to as a third upper branch switch, the sub-branch switch of the third phase is referred to as a third sub-branch switch.

[0004] The power conversion device further includes first to second reactors. The first reactor electrically connects a connection point of the first upper-branch switch and the first sub-branch switch to a first AC terminal. The second reactor electrically connects a connection point of the second upper-branch switch and the second sub-branch switch to a second AC terminal. The third reactor electrically connects a connection point of the third upper-branch switch and the third sub-branch switch to a third AC terminal.

[0005] When 3-phase terminals of the 3-phase AC power source are connected to the first to third AC terminals, respectively, the power conversion device converts AC power supplied to the first to third AC powers into DC power, and outputs the DC power through a high-voltage DC terminal and a low-voltage DC terminal by switching the upper branch switches and the lower branch switches, respectively.

[0006] The power conversion device may further include first to third capacitors, each of which is an X-class capacitor. The first AC terminal is electrically connected to a first terminal of the first capacitor, the second AC terminal is electrically connected to a first terminal of the second capacitor, and the third AC terminal is electrically connected to a first terminal of the third capacitor. Second terminals of the first and third capacitors are electrically connected to each other at a neutral point. The neutral point is connected to a connection point of a pair of DC capacitors. The pair of DC capacitors are connected in series and electrically connected to the high-voltage DC terminal and the low-voltage DC terminal. This configuration can reduce common-mode noise when switching is performed. REFERENCES ACCORDING TO THE PRIOR ART PATENT DOCUMENT

[0007] Patent document 1: JP 6 636 219 B1 SUMMARY OF THE INVENTION

[0008] In addition to the 3-phase AC power source, a power conversion device applicable to a single-phase AC power source is desirable.

[0009] This disclosure aims to provide a power conversion apparatus and program applicable to a 3-phase AC power source or a single-phase AC power source.

[0010] The power conversion device according to this disclosure is a power conversion device (10) comprising: a first AC terminal (Tac1), a second AC terminal (Tac2), a third AC terminal (Tac3), a fourth AC terminal (Tac4), a high-voltage DC terminal (TdcH), a low-voltage DC terminal (TdcL), a series connection element of a first upper-branch switch (S1H) and a first sub-branch switch (S1L), a series connection element of a second upper-branch switch (S2H) and a second sub-branch switch (S2L), a series connection element of a third upper-branch switch (S3H) and a third sub-branch switch (S3L), a series connection element of an upper-branch rectifier (S4H, D4H) and a sub-branch rectifier (S4L, D4L), a first reactor (31),which electrically connects a connection point of the first upper-branch switch and the first sub-branch switch to the first AC terminal, a second choke coil (32) which electrically connects a connection point of the second upper-branch switch and the second sub-branch switch to the second AC terminal, a third choke coil (33) which electrically connects a connection point of the third upper-branch switch and the third sub-branch switch to the third AC terminal, a connecting line (44) which connects a connection point of the upper-branch rectifier and the sub-branch rectifier to the fourth AC terminal, a single-phase charging switch (45) installed in the connecting line, a first capacitor (161), a second capacitor (162), a third capacitor (163), a connecting switch (151), a DC connector (34A, 34B, 34),and a control unit (70). A three-phase AC power source (21) can be connected to the first AC terminal, the second AC terminal, and the third AC terminal. A single-phase AC power source (22) can be connected to the first AC terminal and the fourth AC terminal. The high-voltage terminal of each of the first upper-branch switch, the second upper-branch switch, and the third upper-branch switch and the high-voltage terminal of the upper-branch rectifier are electrically connected to the high-voltage DC terminal. The low-voltage terminal of each of the first sub-branch switch,of the second sub-branch switch and the third sub-branch switch, and the low-voltage terminal of the sub-branch rectifier are electrically connected to the low-voltage DC terminal. The first AC terminal of the first reactor is electrically connected to a first terminal of the first capacitor. The second AC terminal of the second reactor is electrically connected to a first terminal of the second capacitor. The third AC terminal of the third reactor is electrically connected to a first terminal of the third capacitor. Second terminals of the first capacitor, the second capacitor, and the third capacitor are each electrically connected to each other. The second terminals of the first capacitor,The second capacitor and the third capacitor are electrically connected to the DC connector via the connection switch. The DC connector is either a connection point of a first DC capacitor (34A) and a second DC capacitor (34B) connected in series, wherein the first DC capacitor and the second DC capacitor electrically connect the high-voltage DC terminal and the low-voltage DC terminal, or the high-voltage DC terminal or the low-voltage DC terminal. When the control unit determines that the single-phase AC power source is connected to the first AC terminal and the fourth AC terminal, the control unit closes the single-phase charging switch, opens the connection switch, and performs switching control of the first upper-branch switch and the first lower-branch switch.to convert power between the first AC terminal and the fourth AC terminal and the high-voltage DC terminal and the low-voltage DC terminal.

[0011] According to the present disclosure, a single-phase charging switch is provided in a connecting line connecting the connection point of the upper-arm rectifier and the lower-arm rectifier to the fourth AC terminal. When it is determined that the single-phase AC power source is connected to the first AC terminal and the fourth AC terminal, the control unit closes the single-phase charging switch and performs switching control of the first upper-arm switch and the first lower-arm switch, respectively, to perform power conversion between the first AC terminal and the fourth AC terminal, and between the high-voltage DC terminal and the low-voltage DC terminal.According to the present disclosure, a power conversion device applicable to a 3-phase AC power source or a single-phase AC power source is provided.

[0012] According to the present disclosure, the connection switch that electrically connects the second terminals of each of the first to third capacitors and the DC connector is opened in the switching control when the single-phase AC power source is connected. According to this configuration, an overcurrent flowing into the first to third capacitors due to the switching control can be suppressed. Short description of the drawings

[0013] The above and other objects, features, and advantages of the present disclosure will become more apparent from the following detailed description with reference to the accompanying drawings, in which: Fig. 1 shows an overall configuration of an on-board charging device according to a first embodiment, Fig. 2 an on-board charging device to which a 3-phase AC power source is connected, Fig. 3 the vehicle’s own charging device to which a single-phase AC power source is connected, Fig. 4 a flowchart illustrating processes of charging storage batteries, Fig. 5 a block diagram of a 3-phase charging control, Fig. 6 is a time-series diagram illustrating changes in current and voltage in the 3-phase charging control system, Fig. 7 is a timing chart illustrating changes in current and voltage in the 3-phase charging control according to a comparative example. Fig. 8 a block diagram of a single-phase charging controller, Fig. 9 is a time-series diagram illustrating changes in current and voltage in the single-phase charging control, Fig. 10 is a timing chart illustrating an effect of reducing overcurrent according to the first embodiment, Fig. 11 is a time chart showing the case of overcurrent flow according to the comparative example, Fig. 12 shows an overall configuration of an on-vehicle charging device according to a second embodiment, Fig. 13 shows an overall configuration of the vehicle's own charging device according to a third embodiment, Fig. 14 is a flowchart illustrating another process of charging storage batteries, Fig. 15 shows an overall configuration of an on-vehicle charging device according to a fourth embodiment, Fig. 16 is a flowchart illustrating another process of charging storage batteries, Fig. 17 is a timing diagram illustrating a nested (toothed) drive according to other embodiments, Fig. 18 is a timing diagram illustrating a switching control without the nested drive, Fig. 19 shows an overall configuration of an on-board charging device according to another embodiment, and Fig. 20 shows an overall configuration of an on-vehicle charging device according to another embodiment. DESCRIPTION OF EMBODIMENTS

[0014] A variety of embodiments are described with reference to the drawings. In the embodiments, functionally and / or structurally corresponding and / or linked sections are identified by the same reference numerals, or by reference numerals that differ in the hundreds place or higher. For corresponding and / or related sections, reference is made to the description of the other embodiments. First embodiment

[0015] A first embodiment embodying the power conversion device according to the present disclosure will be described below with reference to the drawings. The power conversion device according to this embodiment is, for example, an AC-DC converter mounted on a vehicle such as an electric vehicle and functioning as an on-vehicle charging device.

[0016] The AC power conversion device includes an AC terminal and a DC terminal. The power conversion device has a function of converting AC power supplied to the AC terminal connected to an AC power source outside the vehicle into DC power and outputting DC power through the DC terminal. The DC power output through the DC terminal is supplied to a storage battery of the vehicle. The power conversion device also has a function of converting DC power supplied to the DC terminal into AC power and outputting the AC power through the AC terminal. The power conversion device is applicable to both a three-phase AC power source and a single-phase AC power source.

[0017] As it is in Fig. 1, the power conversion device 10 includes a first AC terminal Tac1, a second AC terminal Tac2, a third AC terminal Tac3, and a fourth AC terminal Tac4, each of which is an AC terminal. As shown in Fig. 2, the first AC terminal Tac1, the second AC terminal Tac2, and the third AC terminal Tac3 can be connected to an external 3-phase AC power source 21. As shown in Fig. 3, the first AC terminal Tac1 and the fourth AC terminal Tac4 can be connected to an external single-phase AC power source 22.

[0018] The power conversion device 10 has a high-voltage DC terminal TdcH and a low-voltage DC terminal TdcL, each of which is a DC terminal. The high-voltage DC terminal TdcH and the low-voltage DC terminal TdcL are connected to an input terminal of a DC-DC converter 24, which constitutes an on-vehicle charging device. An output terminal of the DC-DC converter 24 is connected to a chargeable and dischargeable storage battery 20 installed in the vehicle. The DC-DC converter 24 transforms a DC voltage supplied from the high-voltage DC terminal TdcH and the low-voltage DC terminal TdcL and supplies the transformed DC voltage to the storage battery 20.In addition, the DC-DC converter 24 transforms the DC voltage supplied from the storage battery 20 and supplies it to the high-voltage DC terminal TdcH and the low-voltage DC terminal TdcL. The DC-DC converter 24 includes a transformer connecting the input terminal and the output terminal.

[0019] The power conversion device 10 includes upper-branch switches and sub-branch switches for four phases. The power conversion device 10 includes a series-connected element (series connection element) of a first upper-branch switch S1H and a first sub-branch switch S1L, a series connection element of a second upper-branch switch S2H and a second sub-branch switch S2L, a series connection element of a third upper-branch switch S3H and a third sub-branch switch S3L, and a series connection element of a fourth upper-branch switch S4H and a fourth sub-branch switch S4L. According to this embodiment, each branch switch S1H to S4L is an N-channel MOSFET with a body diode. Therefore, in each branch switch S1H to S4L, a high-voltage terminal is a drain, and a low-voltage terminal is a source. For example, the first phase is the U phase, the second phase is the V phase, and the third phase is the W phase.The fourth upper branch switch S4H is an example of an “upper branch rectifier” and the fourth lower branch switch S4L is an example of a “lower branch rectifier”.

[0020] The power conversion device 10 includes a high-voltage line 30H. The high-voltage line 30H is an electrical line that connects the respective high-voltage terminals of the first upper-branch switch S1H, the second upper-branch switch S2H, the third upper-branch switch S3H, and the fourth upper-branch switch S4H to the high-voltage DC terminal TdcH. The power conversion device 10 includes a low-voltage line 30L. The low-voltage line 30L is an electrical line that connects the respective low-voltage terminals of the first sub-branch switch S1L, the second sub-branch switch S2L, the third sub-branch switch S3L, and the fourth sub-branch switch S4L to the low-voltage DC terminal TdcL. The high-voltage line 30H and the low-voltage line 30L are each formed of conductive members such as busbars.

[0021] The power conversion device 10 includes a series connection element of a first DC capacitor 34A and a second DC capacitor 34B. The series connection element connects the high-voltage line 30H and the low-voltage line 30L. According to this embodiment, the series connection element of the first DC capacitor 34A and the second DC capacitor 34B is an example of a "DC connector."

[0022] The power conversion device 10 has a first path 41, a second path 42, and a third path 43. The first path 41 is an electrical line connecting the low-voltage terminal of the first upper-branch switch S1H and the high-voltage terminal of the first sub-branch switch S1L to the first AC terminal Tac1. The second path 42 is an electrical line connecting the low-voltage terminal of the second upper-branch switch S2H and the high-voltage terminal of the second sub-branch switch S2L to the second AC terminal Tac2. The third path 43 is an electrical line connecting the low-voltage terminal of the third upper-branch switch S3H and the high-voltage terminal of the third sub-branch switch S3L to the third AC terminal Tac3.

[0023] The power conversion device 10 includes a first choke coil 31 on the first path 41, a second choke coil 32 on the second path 42, and a third choke coil 33 on the third path 43. According to this embodiment, the choke coils 31 to 33 each have the same specifications. Therefore, the inductance value of each of the choke coils 31 to 33 is the same. The rated current (specifically, the rated current for a temperature rise) of each of the choke coils 31 to 33 is the same.

[0024] The power conversion device 10 includes an AC filter 35. The AC filter 35 is provided in path 41 closer to the AC terminal Tac1 than the choke coil 31, is provided in path 42 closer to the AC terminal Tac2 than the choke coil 32, and is provided in path 43 closer to the AC terminal Tac3 than the choke coil 33. The filter 35 can be provided, for example, to reduce common-mode noise.

[0025] The power conversion device 10 includes a connecting line 44. The connecting line 44 is an electrical line that connects the low-voltage terminal of the fourth upper-branch switch S4H and the high-voltage terminal of the fourth lower-branch switch S4L to the fourth AC terminal Tac4. The power conversion device 10 includes a single-phase charging switch 45 provided on the connecting line 44. The single-phase charging switch 45 allows current flow in both directions when closed and prevents current flow in both directions when open.

[0026] The power conversion device 10 includes a first capacitor 161, a second capacitor 162, and a third capacitor 163, each of which is an X-class capacitor, and a connection switch 151. A first terminal of the first capacitor 161 is connected to a portion between the first reactor 31 and the AC filter 35 in the first path 41. A first terminal of the second capacitor 162 is connected to a portion between the second reactor 32 and the AC filter 35 in the second path 42. A first terminal of the third capacitor 163 is connected to a portion between the third reactor 33 and the AC filter 35 in the third path 43. Second terminals of each of the first capacitor 161, the second capacitor 162, and the third capacitor 163 are connected to each other at a neutral point.The neutral point is connected to a connection point of the first DC capacitor 34A and the second DC capacitor 34B via the connection switch 151. The connection switch 151 allows current flows in both directions when closed and prevents current distribution in both flows when open.

[0027] The power conversion device 10 includes a DC voltage sensor 50 and an AC voltage sensor 51. The DC voltage sensor 50 detects the voltage of the series connection element of the first DC capacitor 34A and the second DC capacitor 34B.

[0028] The AC voltage sensor 51 detects the voltage between the first AC terminal Tac1 and the fourth AC terminal Tac4.

[0029] The power conversion device 10 includes a first current sensor 61, a second current sensor 62, and a third current sensor 63. The first current sensor 61 detects the current flowing in the first reactor 31, the second current sensor 62 detects the current flowing in the second reactor 32, and the third current sensor 63 detects the current flowing in the third reactor 33. The detected values ​​from each sensor 50, 51, and 61 to 63 are input to the control device 70 provided for the power conversion device 10.

[0030] The control device (control unit) 70 is mainly composed of a microcontroller 71 having a CPU. The functions provided by the microcontroller 71 may be provided by software stored in a tangible storage device and a computer executing them, by software alone, by hardware alone, or a combination thereof. For example, if the microcontroller 71 is provided by an electronic circuit including hardware, it may be provided by a digital or analog circuit including various logic circuits. For example, the microcontroller 71 may execute a program stored in its own memory, a non-volatile tangible storage medium. The program includes, for example, the programs for the processes described below. Fig. 4, Fig. 5, Fig. 8, etc. When the program is executed, the process corresponding to the program is performed. The memory is, for example, a non-volatile memory. The program stored in the memory section can be updated via a communication network such as the Internet, for example, OTA (Over the Air).

[0031] The control device 70 performs a 3-phase charging control or a single-phase charging control. Fig. The flowchart shown in Figure 4 is used below to describe the charging controls.

[0032] In step S10, the control device 70 determines whether a 3-phase charging control command has been given. According to this embodiment, if the control device 70 determines that the 3-phase AC power source 21 is connected to the AC terminals Tac1 to Tac3, as shown in Fig. As shown in Figure 2, the control device 70 provides the three-phase charging control command. In the three-phase AC power source 21, the amplitude and frequency of the output voltage of the three phases are the same, and the phase of the output voltage and output current in each phase are shifted by 120°. Fig. 2, the neutral point of the 3-phase AC power source 21 is connected to the fourth AC terminal Tac4, but the neutral point of the 3-phase AC power source 21 does not need to be connected to the fourth AC terminal Tac4.

[0033] If an affirmative determination is made in step S10, the control device 70 performs the three-phase charging control in steps S11 and S12. In step S11, the control device 70 opens the single-phase charging switch 45, the fourth upper-branch switch S4H, and the fourth lower-branch switch S4L, and closes the connection switch 51.

[0034] In step S12, the control device 70 performs switching control of the first upper-branch switch S1H, the second upper-branch switch S2H, the third upper-branch switch S3H, the first sub-branch switch S1L, the second sub-branch switch S2L, and the third sub-branch switch S3L to convert AC power supplied to the first AC terminal Tac1, the second AC terminal Tac2, and the third AC terminal Tac3 into DC power and output a DC voltage through the high-voltage DC terminal TdcH and the low-voltage DC terminal TdcL. In each phase, the upper-branch switch and the sub-branch switch are alternately closed with a dead time in between. In each phase, the switching cycles of the upper-branch switch and the sub-branch switch are the same.

[0035] Since the connection switch 151 is closed, a ground voltage, which is a voltage between the DC terminal TdcH and the DC terminal TdcL to the neutral point (ground) of the three-phase AC power source 21, is stabilized. As a result, common-mode noise caused by stray capacitance, etc., between the high-voltage line 30H and the low-voltage line 30L to the ground can be reduced.

[0036] If a negative determination is made in step S10, the control device 70 proceeds to step S13 to determine whether the single-phase charging control command is given. According to this embodiment, if the control device 70 determines that the single-phase AC power source 22 is connected to the first AC terminal Tac1 and the fourth AC terminal Tac4, as shown in Fig. 3, the control device 70 determines that the single-phase charging control command is given. In this case, the amplitude of the output voltage of the single-phase AC power source 22 is the same as the amplitude of the output voltage of the three-phase AC power source 21. In addition, the frequency of the output voltage of the single-phase AC power source 22 is the same as the frequency of the output voltage of the three-phase AC power source 21.

[0037] If an affirmative determination is made in step S13, the control device 70 performs the single-phase charging control in steps S14 and S15. In step S14, the control device 70 closes the single-phase charging switch 45 and opens the connection switch 151.

[0038] In step S15, the control device 70 performs switching control of the first upper-arm switch S1H and the first sub-arm switch S1L to convert AC power supplied to the first AC terminal Tac1 and the fourth AC terminal Tac4 into DC power and output the DC power through the high-voltage DC terminal TdcH and the low-voltage DC terminal TdcL. The first upper-arm switch S1H and the first sub-arm switch S1L are synchronously closed alternately with a dead time therebetween. The switching cycle of the first upper-arm switch S1H and the first sub-arm switch S1L is the same as that of the 3-phase charging control. The connection switch 151 is opened to suppress an overcurrent in the first to third capacitors 161 to 163.

[0039] In step S15, the control device 70 closes the fourth sub-branch switch S4L and opens the fourth upper-branch switch S4H during a first period (period) when alternating current flows in the direction from the fourth AC terminal Tac4 to the first AC terminal Tac1 via the single-phase AC power source 22. In contrast, the control device 70 closes the fourth upper-branch switch S4H and opens the fourth sub-branch switch S4L during a second period (period) when current flows in the direction from the first AC terminal Tac1 to the fourth AC terminal Tac4 via the single-phase AC power source 22. The control device 70 can determine, for example, whether the current timing is included in the first period or the second period based on the detected value of the first current sensor 61.

[0040] The switching cycle of the fourth upper-branch switch S4H and the fourth sub-branch switch S4L is the same as the cycle of the output voltage of the single-phase AC power source 22 and is longer than the switching cycle of the first upper-branch switch S1H and the first sub-branch switch S1L. This is because, for the first phase, switching at a high frequency (for example, several tens to hundreds of kHz) is required to reduce the ripple of the current flowing in the reactor 31, whereas for the fourth phase, switching at a frequency equivalent to the fundamental frequency of the output voltage of the single-phase AC power source 22 (for example, 50 Hz or 60 Hz) is sufficient.For this reason, each of the fourth upper-branch switch S4H and the fourth sub-branch switch S4L is a semiconductor switching device with longer on- and off-times than each of the first upper-branch switch S1H and the first sub-branch switch S1L. This allows the use of lower-capacity switches for the fourth upper-branch switch S4H and the fourth sub-branch switch S4L and reduces the cost of the power conversion device 10.

[0041] In the single-phase charging control, when DC power supplied to the DC terminal TdcH and the DC terminal TdcL is converted into AC power and passed through the AC terminal Tac1 and the AC terminal Tac4 by switching control of the first upper-arm switch S1H and the first sub-arm switch S1L, in step S15, the control device 70 opens the fourth upper-arm switch S4H and the fourth sub-arm switch S4L during a period when current flows in the direction from the AC terminal Tac4 to the AC terminal Tac1 via the single-phase AC power source 22.On the other hand, the control device 70 closes the fourth sub-branch switch S4L and opens the fourth upper-branch switch S4H during a second period of time when current flows in the direction from the first AC terminal Tac1 to the fourth AC terminal Tac4 via the single-phase AC power source 22.

[0042] The following is a description of the 3-phase charging control with reference to Fig. 5. Fig. 5 shows a block diagram of the 3-phase charging control performed by the control device 70.

[0043] The voltage control unit 80 calculates a d-axis target current Idref for controlling the voltage detected by the DC voltage sensor 50 (hereinafter referred to as the detected DC voltage Vdcr) to a target DC voltage Vdcref. The voltage control unit 80 includes a voltage deviation calculation unit 81 and a voltage regulation unit 82. The voltage deviation calculation unit 81 calculates a voltage deviation ΔV by subtracting the detected DC voltage Vder from the target DC voltage Vdcref. The target DC voltage Vdcref can be set based on the rated voltage of each upper-branch switch and each lower-branch switch S1H to S4L and the DC-DC converter 24, for example.

[0044] The voltage control unit 82 calculates the d-axis target current Idref, which is the manipulated variable for feedback control to cause the voltage deviation ΔV to approach 0. The feedback control performed by the voltage control unit 82 is, for example, PI control (PI control).

[0045] An electrical angle calculation unit 83 calculates an electrical angle θe based on the voltage detected by the AC voltage sensor 51 (hereinafter referred to as AC voltage detection value V1r). According to this embodiment, the electrical angle θe is set to 0° at the zero-crossing time point of the AC voltage detection value V1r (specifically, for example, the zero-up crossing time point), and the electrical angle θe is set to 360° at the next zero-up crossing time point. In this way, one cycle of the AC voltage detection value V1r corresponds to one cycle of the electrical angle (0° to 360°). In this system, the sign of the AC voltage detection value V1r is defined as positive for the state where the voltage of the first AC terminal Tac1 is higher than the voltage of the fourth AC terminal Tac4.

[0046] A 2-phase conversion unit 84 converts the first detected current value i1r, the second detected current i2r, and the third detected current i3r into a d-axis current Idr and a q-axis current Iqr in the 2-phase rotation coordinate system (dq-axis coordinate system) based on currents detected by each of the first current sensor 61, the second current sensor 62, and the third current sensor 63 (hereinafter referred to as a first detected current i1r, a second detected current i2r, and a third detected current i3r) and the electrical angle. Each of the first detected current i1r, the second detected current i2r, and the third detected current i3r is a value in the fixed 3-phase coordinate system (3-phase fixed coordinate system).In this system, the sign of each of the first detected current i1r, the second detected current i2r, and the third detected current i3r is defined as positive for the state where the first detected current i1r flows from the first AC terminal Tac1 to the first reactor 31, the second detected current i2r flows from the second AC terminal Tac2 to the second reactor 32, and the third detected current i3r flows from the third AC terminal Tac3 to the third reactor 33.

[0047] The current control unit 85 includes a d-axis deviation calculation unit 86, a d-axis control unit 87, a q-axis deviation calculation unit 88, and a q-axis control unit 89.

[0048] The d-axis deviation calculation unit 86 calculates a d-axis current deviation ΔId by subtracting the d-axis current Idr from a d-axis command current Idref. The d-axis control unit 87 calculates a d-axis command voltage Vdref, which is the manipulated variable for control, to cause the d-axis current deviation ΔId to approach 0. The d-axis control in the control unit 87 is, for example, a proportional-integral control.

[0049] The q-axis deviation calculation unit 88 calculates a q-axis current deviation ΔIq by subtracting the q-axis current Iqr from the q-axis command current Iqref. The q-axis command current Iqref is a command value of a reactive current, which, according to this embodiment, is set to 0 to cause the power factor to be 1. Setting the power factor to 1 means setting the phase difference between each of the first output voltage V1, the second output voltage V2, and the third output voltage V3 of the 3-phase AC power source 21 and each of the first detected current i1r, the second detected current i2r, and the third detected current i3r to 0. The q-axis control unit 89 performs control to cause the q-axis current deviation ΔIq to approach zero. The control performed by the q-axis control unit 89 is, for example, a PI control.

[0050] Based on the d-axis command voltage Vdref, the q-axis command voltage Vqref, and the electrical angle θe, the three-phase conversion unit 90 converts the d-axis command voltage Vdref and the q-axis command voltage Vqrefd in the two-phase rotation coordinate system into a first command voltage V1eg1ref, a second command voltage V1eg2ref, and a third command voltage V1eg3ref in the three-phase rotation coordinate system. The first command voltage V1eg1ref, the second command voltage V1eg2ref, and the third command voltage V1eg3 are phase-shifted by 120° in the electrical angle, and each is essentially a sine wave. A sine wave is a signal that is zero at every 180° in the electrical angle.

[0051] A PWM generating means 91 generates a first upper arm drive signal, a first sub-arm drive signal, a second upper arm drive signal, a second sub-arm drive signal, a third upper arm drive signal, and a third sub-arm drive signal based on pulse width modulation (PWM) based on a magnitude comparison of each of the first target voltage V1eg1ref, the second target voltage V1eg2ref, and the third target voltage V1eg3ref and a carrier signal.The first upper-arm drive signal is supplied to the first upper-arm switch S1H, the first sub-arm drive signal is supplied to the first sub-arm switch S1L, the second upper-arm drive signal is supplied to the second upper-arm switch S2H, the second sub-arm drive signal is supplied to the second sub-arm switch S2L, the third upper-arm drive signal is supplied to the third upper-arm switch S3H, and the third sub-arm drive signal is supplied to the third sub-arm switch S3L. The carrier signal can be, for example, a triangular wave signal. One cycle of the carrier signal is sufficiently shorter than one cycle of the electrical angle (0° to 360°).The switching patterns of the first upper branch switch S1H and the first sub-branch switch S1L, the switching patterns of the second upper branch switch S2H and the second sub-branch switch S2L and the switching patterns of the third upper branch switch S3H and the third sub-branch switch S3L are offset from each other in phase by 120°.

[0052] Fig. 6 shows changes in the first output voltage V1, the second output voltage V2, the third output voltage V3, the first detected current i1r, the second detected current i2r, the third detected current i3r, a high-potential-to-ground voltage Vdcp, and a low-potential-to-ground voltage Vdcn of the three-phase AC power source 21 when the three-phase charging control is performed. The first output voltage V1, the second output voltage V2, and the third output voltage V3 are the voltages of the first AC terminal Tac1, the second AC terminal Tac2, and the third AC terminal Tac3, respectively. The first output voltage V1, the second output voltage V2, and the third output voltage V3 are each defined as positive in the state where all of them are higher than the voltage at the neutral point of the three-phase AC power source 21.The high potential-to-ground voltage Vdcp is a voltage of the high-voltage DC terminal TdcH with respect to the ground voltage, and the low potential-to-ground voltage Vdcn is a voltage of the low-voltage DC terminal TdcL with respect to the ground voltage.

[0053] In the Fig. In the example shown in Figure 6, the frequency of the output voltages V1 to V3 of the 3-phase AC power source 21 is set to 50 Hz and the target DC voltage Vdcref is set to 800 V.

[0054] As it is in Fig. 6, the 3-phase charging control is performed such that the phase difference between the first output voltage V1 and the first detected current i1r, between the second output voltage V2 and the second detected current i2r, and between the third output voltage V3 and the third detected current i3r is 0 (ie, so that the power factor is 1).

[0055] In the three-phase charging control, the high-potential-to-ground voltage Vdcp and the low-potential-to-ground voltage Vdcn do not oscillate at the high switching frequency of the first upper-branch switch S1H and the first lower-branch switch S1L, respectively. This is because the connection point at the second terminals of the X-class capacitors, the first to third capacitors 161 to 163, act as virtual neutral points. This reduces common-mode noise caused by stray capacitance, etc., between the high-voltage line 30H and the low-voltage line 30L to the ground, thereby enabling a downsizing of the AC filter 35.

[0056] Fig. 7 shows, as a comparative example, the case where the connection switch 151 is open in the three-phase charging control. In this case, the connection point of the second terminal of the first to third capacitors 161 to 163 and the connection point of the DC capacitor 34a and the DC capacitor 34b are electrically isolated from each other. Therefore, the high-potential-to-ground voltage Vdcp and the low-potential-to-ground voltage Vdcn oscillate at the high switching frequency of the upper-branch switch S1H and the lower-branch switch S1L, resulting in the need for a larger AC filter 35.

[0057] The control device 70 may perform switching control of the first upper-branch switch S1H and the first lower-branch switch S1L based on average current mode control, etc., instead of the Fig. 5 shown control as the 3-phase charging control.

[0058] The single-phase charging control is described below with reference to Fig. 8 described. Fig. 8 shows a block diagram of the single-phase charging control performed by the control device 70.

[0059] The filter 112 of the control device 70 performs low-pass filtering on the target DC voltage Vdcr. This process removes harmonic components of the output voltage of the single-phase AC power source 22 contained in the target DC voltage Vdcr. The harmonic components are, for example, second-order frequency components of the output voltage (e.g., 100 Hz or 120 Hz).

[0060] The voltage control unit 101 includes a voltage deviation calculation unit 102 and a voltage regulation unit 103. The voltage deviation calculation unit 102 calculates the voltage deviation ΔV by subtracting the detected DC voltage Vdcref from the target DC voltage Vdcr, from which the harmonic components have been removed by the filter 112. The voltage regulation unit 103 calculates the target current amplitude Iampref, which is a manipulated variable for control to cause the voltage deviation ΔV to approach 0. The control performed by the voltage regulation unit 103 is, for example, PI control.

[0061] The electrical angle calculation unit 83 calculates the electrical angle θe based on the AC voltage detection value V1r. A sine wave generator 109 generates a sine wave signal "SIN θe" based on the electrical angle θe.

[0062] The current control unit 105 has a target current calculation unit 106, a current deviation calculation unit 107 and a current control unit 108.

[0063] The target current calculation unit 106 calculates a target current Iacref by multiplying the target current amplitude Iampref by the sine wave signal "SIN θe." The target current Iacref fluctuates at the same period as the AC voltage detection value V1r.

[0064] The current deviation calculation unit 107 calculates a current deviation ΔI by subtracting the total value of the first detected current i1r and the second detected current i2r from the target current Iacref. The total value of the first detected current i1r and the second detected current i2r is calculated by a current addition unit 110.

[0065] The current control unit 108 calculates a first target voltage V1eg1ref, which is a manipulated variable for control to cause the current deviation ΔI to approach 0. The control performed by the current control unit 108 is, for example, a PI control.

[0066] The PWM generating means 111 generates the first upper arm drive signal and the first sub-arm drive signal to be supplied to the gates of the first upper arm switch S1H and the first sub-arm switch S1L, respectively, by pulse width modulation based on a magnitude comparison (large-to-small comparison) between the first target voltage V1eg1ref and the carrier signal.

[0067] Fig. 9 shows changes in the output voltage Vac, the output current iac, the high-potential-to-ground voltage Vdcp, and the low-potential-to-ground voltage Vdcn of the single-phase AC power source 22 when the single-phase charging control is performed. The output voltage Vac of the single-phase AC power source 22 is defined as positive in the state where the voltage at the first AC terminal Tac1 is higher than the voltage at the fourth AC terminal Tac4. The output current iac of the single-phase AC power source 21 is defined as positive in the state where it flows from the fourth AC terminal Tac4 to the first AC terminal Tac1.

[0068] In the Fig. In the example shown in Figure 9, the frequency of the output voltage Vac of the single-phase AC power source 22 is set to 50 Hz, the effective value of the output voltage Vac is set to 230 Vrms, and the target DC voltage Vdcref is set to 800 V.

[0069] The high-frequency switching control of the first upper-branch switch S1H and the first sub-branch switch S1L and the 50 Hz switching control of the fourth upper-branch switch S4H and the fourth sub-branch switch S4L are performed for the single-phase charging control such that the phase difference between the output voltage Vac and the output current iac of the single-phase AC power source 22 is zero (that is, the power factor is 1).

[0070] Fig. 10 shows changes in the output voltage Vac of the single-phase AC power source 22, the high-potential-to-ground voltage Vdcp, the low-potential-to-ground voltage Vdcn, the switching state of the first upper-arm switch A1H, a terminal voltage Vcx1 of the first capacitor 161, and a current ixc1 flowing in the first capacitor 161 when the single-phase charging control is performed. Since the connection switch 151 is open when the single-phase charging control is performed, no overcurrent flows through the first capacitor 161 due to the switching control of the first upper-arm switch S1H and the first sub-arm switch S1L according to this embodiment.

[0071] Fig. 11 shows a time course diagram that Fig. 10 when the comparative example performs single-phase charging control. In the comparative example, the connection switch 151 remains closed in single-phase charging control.

[0072] In the comparative example, each time the fourth upper-branch switch S4H and the fourth lower-branch switch S4L are switched, the terminal voltage of the first capacitor 161 changes suddenly, and this sudden change causes a flow of a resonance current in the first capacitor 161, resulting in an overcurrent in the first capacitor 161. In the Fig. 11, the current flowing in the first capacitor 161 exceeds the allowable upper limit current Ilim of the first capacitor 161.

[0073] As described above, according to this embodiment, common mode noise in the 3-phase charging control is reduced by the first to third capacitors 161 to 163, while the overcurrent in the first to third capacitors 161 to 163 is suppressed when the single-phase charging control is performed. Second embodiment

[0074] A second embodiment will be described below with reference to the drawings, focusing on the differences from the first embodiment. According to this embodiment, as shown in Fig. As shown in Fig. 12, the neutral point of the first to third capacitors 161 to 163 is connected to one terminal of the connection switch 151 and a portion closer to the DC capacitor 34a and the DC capacitor 34b than the single-phase charging switch 45 in the connection line 44. This allows the first to third capacitors 161 to 163 to function as X-class capacitors when the single-phase charging control is performed and to reduce the fluctuations in the high-potential-to-ground voltage Vdcp and the low-potential-to-ground voltage Vdcn.

[0075] The 3-phase charging control and the single-phase charging control according to this embodiment are respectively the same as the control shown in Fig. 4, Fig. 5 and Fig. 8 according to the first embodiment. When single-phase charging control is performed, the first capacitor 161 connects the first path 41 to the connection point of the fourth upper-arm switch S4H and the fourth lower-arm switch S4L. This provides a filtering effect to reduce normal-mode noise (normal-mode noise) and common-mode noise.

[0076] On the other hand, when the 3-phase charging control is performed, since the fourth upper-arm switch S4H and the fourth sub-arm switch S4L are kept open, even though the first capacitor 161 electrically connects the first path 41 to the connection point of the fourth upper-arm switch S4H and the fourth sub-arm switch S4L, this does not adversely affect the filtering performance of the first to third capacitors 161 to 163.

[0077] According to the above-described embodiment, the X-class capacitor can be shared between the three-phase charging control and the single-phase charging control. Therefore, it is not necessary to provide a new dedicated X-class capacitor for the single-phase charging control, and the power conversion device 10 can be downsized. Third embodiment

[0078] A third embodiment is described below with reference to the drawings, focusing on the differences from the first embodiment. As shown in Fig. 13, the power conversion device 10 according to the third embodiment includes a second single-phase charging switch 46. The second single-phase charging switch 46 connects the portion in the first path 41 that is closer to the AC terminal Tac1 than the first reactor 31 and the portion in the second path 42 that is closer to the AC terminal Tac2 than the second reactor 32. The second single-phase charging switch 46 allows current flows in both directions when closed and prevents current flows in both directions when open. For example, the second single-phase charging switch 46 may connect the first AC terminal Tac1 and the second AC terminal Tac2. According to this embodiment, the single-phase charging switch 46 is referred to as the first single-phase charging switch 45.

[0079] Next, explanations will be given of the 3-phase charging control or the single-phase charging control performed by the control device 70 with reference to Fig. 14.

[0080] In step S20, the control device 70 determines whether a 3-phase charging control instruction is given, as in step S10.

[0081] If an affirmative determination is made in step S20, the control device 70 performs three-phase charging control in steps S21 and S22. In step S21, the control device 70 opens the first single-phase charging switch 45, the second single-phase charging switch 46, the fourth upper-branch switch S4H, and the fourth lower-branch switch S4L, and closes the connection switch 151.

[0082] In step S22, the control device 70 performs switching control of the first upper-arm switch S1H, the second upper-arm switch S2H, the third upper-arm switch S3H, the first sub-arm switch S1L, the second sub-arm switch S2L, and the third sub-arm switch S3L, as in step S12, to convert AC power supplied to the first AC terminal Tac1, the second AC terminal Tac2, and the third AC terminal Tac3 into DC power for output via the high-voltage DC terminal TdcH and the low-voltage DC terminal TdcL.

[0083] If a negative determination is made in step S20, the control device 70 proceeds to step S23. In step S23, the control device 70 determines whether the single-phase charging control command is given, as in step S13.

[0084] If an affirmative determination is made in step S23, the control device 70 performs the single-phase charging control in step S24 and step S25. In step S24, the control device 70 closes the first single-phase charging switch 45 and the second single-phase charging switch 46 and opens the connection switch 151.

[0085] In step S25, the control device 70 performs switching control of the first upper-branch switch S1H, the first sub-branch switch S1L, the second upper-branch switch S2H, and the second sub-branch switch S2L to convert AC power supplied to the first AC terminal Tac1 and the fourth AC terminal Tac4 into DC power for output via the high-voltage DC terminal TdcH and the low-voltage DC terminal TdcL. In each phase, the upper-branch switch and the sub-branch switch are alternately closed with a dead time between them. In each phase, a switching cycle of the upper-branch switch and the sub-branch switch is the same as that in the 3-phase charging control.

[0086] In step S25, the control device 70 closes the fourth sub-branch switch S4L and opens the fourth upper-branch switch S4H during a first period when the alternating current flows in the direction from the fourth AC terminal Tac4 to the first AC terminal Tac1 via the single-phase AC power source 22. In contrast, the control device 70 closes the fourth upper-branch switch S4H and opens the fourth sub-branch switch S4L during a second period when current flows in the direction from the first AC terminal Tac1 to the fourth AC terminal Tac4 via the single-phase AC power source 22.

[0087] According to the third embodiment described above, since the second single-phase charging switch 46 is closed when the single-phase charging control is performed, the first reactor 31 and the second reactor 32 can be used as power transmission paths. This makes it possible to increase the DC power output through the high-voltage DC terminal TdcH and the low-voltage DC terminal TdcL.

[0088] According to the third embodiment, it is possible to improve the common mode noise reduction effect because the second capacitor 162 can also provide a function as a filter when the single-phase charging control is performed. Fourth embodiment

[0089] A fourth embodiment will be described below with reference to the drawings, focusing on the differences from the third embodiment. According to this embodiment, as shown in Fig. As shown in FIG. 15, the power conversion device 10 includes a series connection element of a compensation capacitor 47 and a compensation switch 48 as a configuration for reducing pulsation of DC power output via the DC terminal TdcH and the DC terminal TdcL. The series connection element connects the high-voltage power 30H and the portion of the third path 43 that is closer to the third AC terminal Tac3 than to the third reactor 33. The compensation capacitor 47 may be, for example, a film capacitor. The compensation switch 48 allows current flows in both directions when closed and prevents current flows in both directions when open. The series connection element of the compensation capacitor 47 and the compensation switch 48 can connect the high voltage line 30H and the third AC terminal Tac3.The compensation capacitor 47 may be positioned closer to the high voltage line 30H than the compensation switch 48.

[0090] The power conversion device 10 includes a compensation voltage sensor 52. The compensation voltage sensor 52 detects the terminal voltage of the compensation capacitor 47. The detected value of the voltage of the compensation capacitor 47 is input to the control device 70.

[0091] The 3-phase charging control or the single-phase charging control performed by the control device 70 are described with reference to Fig. 16 described.

[0092] In step S30, the control device 70 determines whether the 3-phase charging control instruction is given, as in step S20.

[0093] If an affirmative determination is made in step S30, the control device 70 performs three-phase charging control in steps S31 and S32. In step S31, the control device 70 opens the first single-phase charging switch 45, the second single-phase charging switch 46, the compensation switch 48, the fourth upper-branch switch S4H, and the fourth lower-branch switch S4L, and closes the connection switch 151.

[0094] In step S32, as in step S22, the control device 70 performs switching control of the first upper-arm switch S1H, the second upper-arm switch S2H, the third upper-arm switch S3H, and the first sub-arm switch S1L, the second sub-arm switch S2L, and the third sub-arm switch S3L to convert AC power supplied to the AC terminal Tac1, the AC terminal Tac2, and the AC terminal Tac3 into DC power and output via the high-voltage DC terminal TdcH and the low-voltage DC terminal TdcL.

[0095] When a negative determination is made in step S30, the control device 70 proceeds to step S33 and determines whether the single-phase charging control instruction is given, as in step S23.

[0096] If an affirmative determination is made in step S33, the control device 70 performs single-phase charging control in step S34 and step S35. In step S34, the control device 70 closes the first single-phase charging switch 45, the second single-phase charging switch 46, and the compensation switch 48, and opens the connection switch 151.

[0097] In step S35, the control device 70 performs switching control of the first upper-branch switch S1H, the first sub-branch switch S1L, the second upper-branch switch S2H, and the second sub-branch switch S2L to convert AC power supplied to the first AC terminal Tac1 and the fourth AC terminal Tac4 into DC power for output via the high-voltage DC terminal TdcH and the low-voltage DC terminal TdcL. In each phase, the upper-branch switch and the sub-branch switch are alternately closed with a dead time between them. In each phase, a switching cycle of the upper-branch switch and the sub-branch switch is the same as that of the 3-phase charging control.

[0098] The control device 70 performs switching control of the third upper-arm switch S3H and the third sub-arm switch S3L based on the detection value of the compensation voltage sensor 52 to reduce the pulsation of the DC power output through the high-voltage DC terminal TdcH and the low-voltage DC terminal TdcL by charging and discharging the compensation capacitor 47. The third upper-arm switch S3H and the third sub-arm switch S3L are alternately closed with a dead time therebetween. A switching cycle of the third upper-arm switch S3H and the sub-arm switch S3L is the same as that of the first upper-arm switch S1H, the first sub-arm switch S1L, the second upper-arm switch S2H, and the second sub-arm switch S2L.

[0099] In step S35, as in step S25, the control device 70 closes the fourth sub-branch switch S4L and opens the fourth upper-branch switch S4H during a first period when an alternating current flows in the direction from the fourth AC terminal Tac4 to the first AC terminal Tac1 via the single-phase AC power source 22. In contrast, during a second period when current flows in the direction from the AC terminal Tac1 to the AC terminal Tac4 via the single-phase AC power source 22, the control device 70 closes the fourth upper-branch switch S4H and opens the fourth sub-branch switch S4L.

[0100] According to the fourth embodiment described above, the pulsation of DC power can be reduced while increasing the DC power output from the power conversion device 10 in single-phase charging control. As a result, the capacitance of the DC capacitor 34A and the DC capacitor 34B can be reduced, and the DC capacitor 34A and the DC capacitor 34B can be made smaller. Other embodiments

[0101] Each of the embodiments described above can be implemented with the following modifications.

[0102] The configuration described in the third and fourth embodiments can be applied to the second embodiment.

[0103] In the Fig. 15 according to the fourth embodiment, instead of the high-voltage line 30H, the low-voltage line 30L may be connected to the third path 43 via the series connection element of the compensation capacitor 47 and the compensation switch 48.

[0104] According to the fourth embodiment, instead of the compensation capacitor 47, for example, a small-capacity storage battery that can be charged and discharged may be provided.

[0105] According to the third and fourth embodiments, the control device 70 can perform drives (controls) of the first upper branch switch S1H, the first lower branch switch S1L, the second upper branch switch S2H, and the second lower branch switch S2L in the single-phase charging control as shown in Fig. 17. Nested control is a switching control in which the switching time of the first upper-branch switch S1H for closing and the switching time of the second upper-branch switch S2H for closing are shifted by 180° in electrical angle. Fig. 17 also shows the first and second detected currents i1r, i2r and the currents flowing in each DC capacitor 34A, 34B in the case of interleaved driving. Fig. 18 shows a switching control without nested control as a comparison example. Tsw1 and Tsw2 in Fig. 17 and Fig. 18 show a switching cycle for the first upper branch switch S1H and the second upper branch switch S2H.

[0106] In the interleaved drive, the current flowing in the first choke coil 31 and the current flowing in the second choke coil 32 flow in such a way that they cancel each other's current ripple. This reduces the current ripple components flowing into and out of each of the DC capacitors 34A, 34B, which vary with the switching frequency of the first upper-branch switch S1H, the first lower-branch switch S1L, the second upper-branch switch S1H, and the second lower-branch switch S2L. As a result, the ripple current rating of each DC capacitor 34A, 34B can be reduced, which in turn reduces the capacitance of each DC capacitor 34A, 34B, and allows the DC capacitors 34A, 34B to be smaller.

[0107] In the case of single-phase charging control, if no bidirectional power conversion is performed and only one-way power conversion from AC power to DC power is performed, as described in Fig. 19, an upper-arm diode D4H and a sub-arm diode D4L may be provided instead of the fourth upper-arm switch S4H and the fourth sub-arm switch S4L. In this case, the cathodes of the upper-arm diode D4H and the sub-arm diode D4L are an example of a "high-voltage terminal," and the anodes are an example of the "low-voltage terminal."

[0108] As it is in Fig.20, the power conversion device 10 may be provided with a DC capacitor 34 instead of the series connection element of the first capacitor 34A and the second capacitor 34B. In this case, the connection switch 151 may connect a connection point of the second terminals of the first to third capacitors 161 to 163 to the high-voltage line 30H. In this case, the connection switch 151 connects the connection point at the second terminals of the first to third capacitors 161 to 163 and the high-voltage DC terminal TdcH (an example of "DC connector").

[0109] The connection switch 151 may also connect the connection point at the second terminals of the first to third capacitors 161 to 163 to the low-voltage line 30L. In this case, the connection switch 151 connects the connection point at the second terminals of the first to third capacitors 161 to 163 and the low-voltage DC terminal TdcL (an example of the "DC connector").

[0110] The power conversion device 10 may have only the second function of two functions: the first function being a function of converting AC power supplied to the AC terminal from an external AC power source into DC power and outputting it through the DC terminal, and the second function being a function of converting DC power supplied to the DC terminal into AC power and outputting it through the AC terminal.

[0111] The AC filter 35 does not need to be provided.

[0112] The first upper-branch switch can comprise multiple N-channel MOSFETs connected in parallel. The same applies to the first lower-branch switch and the second through fourth branch switches.

[0113] The upper and lower branch switches are not limited to N-channel MOSFETs, but can be, for example, IGBTs with freewheeling diodes connected in reverse parallel. In this case, the collector of the IGBT corresponds to the high-voltage terminal, and the emitter corresponds to the low-voltage terminal.

[0114] Instead of the first DC capacitor 34A and the second DC capacitor 34B and the DC capacitor 34, for example, a small-capacity storage battery that can be charged and discharged may be provided.

[0115] The storage unit connected to the output of the DC-DC converter 24 is not limited to a storage battery, but may be, for example, a high-capacity electric double-layer capacitor or both a storage battery and an electric double-layer capacitor.

[0116] The mobile unit on which the power conversion device is mounted is not limited to vehicles, but can be, for example, an aircraft or a ship. The unit on which the power conversion device is mounted is not limited to a mobile vehicle, but can also be a stationary device.

[0117] The control unit and methods described in this disclosure may be implemented by a dedicated computer provided by having a processor and a memory programmed to perform one or more functions embodied in a computer program. Alternatively, the control unit and methods described in this disclosure may be implemented by a dedicated computer provided by configuring the processor with one or more dedicated hardware logic circuits.Alternatively, the control unit and its methods described in this disclosure may be implemented by one or more dedicated computers, implemented by a combination of the processor and a memory programmed to perform one or more functions, and a processor configured by one or more dedicated hardware logic circuits. The computer program may also be stored in a computer-readable non-transitory recording medium as instructions to be executed by a computer.

[0118] Although this disclosure has been described according to examples, it should be understood that this disclosure is not limited to these examples or structures. The present disclosure also encompasses various variations and transformations within the range of equivalence. In addition, various combinations and forms, as well as other combinations and forms including only one element, more or less of which, are also within the scope and spirit of this disclosure. QUOTES CONTAINED IN THE DESCRIPTION

[0000] This list of documents submitted by the applicant was generated automatically and is included solely for the convenience of the reader. This list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions. Cited patent literature

[0000] JP 2022-175108

[0001] JP 6 636 219 B1

[0007]

Claims

[1] Power conversion device (10) comprising: a first AC connection (Tac1), a second AC connection (Tac2), a third AC connection (Tac3), a fourth AC connection (Tac4), a high-voltage direct current connection (TdcH), a low-voltage direct current (TdcL) connection, a series connection element of a first upper branch switch (S1H) and a first lower branch switch (S1L), a series connection element of a second upper branch switch (S2H) and a second lower branch switch (S2L), a series connection element of a third upper branch switch (S3H) and a third lower branch switch (S3L), a series connection element of an upper branch rectifier (S4H, D4H) and a lower branch rectifier (S4L, D4L), a first choke coil (31) electrically connecting a connection point of the first upper branch switch and the first lower branch switch to the first AC terminal, a second choke coil (32) electrically connecting a connection point of the second upper branch switch and the second lower branch switch to the second AC terminal, a third choke coil (33) electrically connecting a connection point of the third upper branch switch and the third lower branch switch to the third AC terminal, a connecting line (44) connecting a connection point of the upper branch rectifier and the lower branch rectifier to the fourth AC terminal, a single-phase charging switch (45) installed in the connecting line, a first capacitor (161), a second capacitor (162), a third capacitor (163), a connection switch (151), a DC connector (34A, 34B, 34), and a control unit (70), wherein a 3-phase AC power source (21) can be connected to the first AC terminal, the second AC terminal and the third AC terminal, a single-phase AC power source (22) can be connected to the first AC terminal and the fourth AC terminal, the high-voltage terminal of each of the first upper-branch switch, the second upper-branch switch and the third upper-branch switch and the high-voltage terminal of the upper-branch rectifier are electrically connected to the high-voltage DC terminal, the low-voltage terminal of each of the first sub-branch switch, the second sub-branch switch and the third sub-branch switch and the low-voltage terminal of the sub-branch rectifier are electrically connected to the low-voltage DC terminal, the first AC terminal of the first choke coil is electrically connected to a first terminal of the first capacitor, the second AC terminal of the second choke coil is electrically connected to a first terminal of the second capacitor, the third AC terminal of the third choke coil is electrically connected to a first terminal of the third capacitor, second terminals of the first capacitor, the second capacitor and the third capacitor are each electrically connected to each other, the second terminals of the first capacitor, the second capacitor and the third capacitor are electrically connected to the DC connector via the connection switch, the DC connector is one of the following: a connection point of a first DC capacitor (34A) and a second DC capacitor (34B) connected in series, the first DC capacitor and the second DC capacitor electrically connecting the high-voltage DC terminal and the low-voltage DC terminal;the high-voltage DC terminal, and the low-voltage DC terminal, wherein, when the control unit determines that the single-phase AC power source is connected to the first AC terminal and the fourth AC terminal, the control unit closes the single-phase charging switch, opens the connection switch, and performs switching control of the first upper-branch switch and the first lower-branch switch to convert power between the first AC terminal and the fourth AC terminal and the high-voltage DC terminal and the low-voltage DC terminal; [2] The power conversion device according to claim 1, wherein the second terminals of the first capacitor, the second capacitor, and the third capacitor are electrically connected to a portion of the connecting line that is closer to the connection point of the upper arm rectifier and the lower arm rectifier than the single-phase charging switch. [3] Power conversion device according to claim 1 or 2, wherein the upper branch rectifier allows a current flow from the low-voltage terminal of the upper branch rectifier to the high-voltage terminal of the upper branch rectifier, and the sub-branch rectifier allows current to flow from the low-voltage terminal of the sub-branch rectifier to the high-voltage terminal of the sub-branch rectifier. [4] Power conversion device according to claim 3, wherein the upper branch rectifier is a fourth upper branch switch (S4H) with a reverse parallel connected diode, the sub-branch rectifier is a fourth sub-branch switch (S4L) with a reverse parallel connected diode, when the control unit determines that the 3-phase AC power source is connected to the first AC terminal, the second AC terminal, and the third AC terminal, the control unit opens the fourth upper branch switch and the fourth lower branch switch, and when the control unit determines that the single-phase AC power source having the first AC terminal and the fourth AC terminal, the control unit performs switching control and closes the fourth upper branch switch and the fourth lower branch switch alternately. [5] A program to be executed by a computer of a power conversion device (10), the power conversion device comprising: a first AC connection (Tac1), a second AC connection (Tac2), a third AC connection (Tac3), a fourth AC connection (Tac4), a high-voltage direct current connection (TdcH), a low-voltage direct current (TdcL) connection, a series connection element of a first upper branch switch (S1H) and a first lower branch switch (S1L), a series connection element of a second upper branch switch (S2H) and a second lower branch switch (S2L), a series connection element of a third upper branch switch (S3H) and a third lower branch switch (S3L), a series circuit element of an upper branch rectifier (S4H, D4H) and a lower branch rectifier (S4L, D4L), a first choke coil (31) electrically connecting a connection point of the first upper branch switch and the first lower branch switch to the first AC terminal, a second choke coil (32) electrically connecting a connection point of the second upper branch switch and the second lower branch switch to the second AC terminal, a third choke coil (33) electrically connecting a connection point of the third upper branch switch and the third lower branch switch to the third AC terminal, a connecting line (44) connecting a connection point of the upper branch rectifier and the lower branch rectifier to the fourth AC terminal, a single-phase charging switch (45) installed in the connecting line, a first capacitor (161), a second capacitor (162), a third capacitor (163), a connection switch (151), and a DC connector (34A, 34B, 34), wherein a 3-phase AC power source (21) can be connected to the first AC terminal, the second AC terminal and the third AC terminal, a single-phase AC power source (22) can be connected to the first AC terminal and the fourth AC terminal, the high-voltage terminal of each of the first upper-branch switch, the second upper-branch switch and the third upper-branch switch and the high-voltage terminal of the upper-branch rectifier are electrically connected to the high-voltage DC terminal, the low-voltage terminal of each of the first sub-branch switch, the second sub-branch switch and the third sub-branch switch and the low-voltage terminal of the sub-branch rectifier are electrically connected to the low-voltage DC terminal, the first AC terminal of the first choke coil is electrically connected to a first terminal of the first capacitor, the second AC terminal of the second choke coil is electrically connected to a first terminal of the second capacitor, the third AC terminal of the third choke coil is electrically connected to a first terminal of the third capacitor, second terminals of the first capacitor, the second capacitor and the third capacitor are each electrically connected to each other, the second terminals of the first capacitor, the second capacitor and the third capacitor are electrically connected to the DC connector via the connection switch, the DC connector is either a connection point of a first DC capacitor (34A) and a second DC capacitor (34B) connected in series, the first DC capacitor and the second DC capacitor electrically connecting the high-voltage DC terminal and the low-voltage DC terminal; the high-voltage DC terminal or the low-voltage DC terminal, where the program causes the computer, when the computer determines that the single-phase AC power source is connected to the first AC terminal and the fourth AC terminal, closes the single-phase charging switch, opens the connection switch, and performs switching control of the first upper branch switch and the first lower branch switch to convert power between the first AC terminal and the fourth AC terminal and the high-voltage DC terminal and the low-voltage DC terminal.

Images