JP2014064431A - Multilevel power conversion device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a multilevel power conversion device of a compact size by reducing the number of flying capacitors.SOLUTION: A basic circuit 2 has N (N≥2) first basic cells in each of which a switching element S, a flying capacitor Cand a switching element Sare sequentially connected in series between positive and negative electrodes of DC voltage sources C, C. As for expansion circuits 3, a second basic cell is connected in parallel with the flying capacitor Cof each first basic cell and a further second basic cell is connected in parallel with a flying capacitor of the second basic cell until this is repeated K times to connect K (K≥1) second basic cells. Phase modules 41, 42, ..., 4M each have a switching element between each input terminal and an output terminal, and selectively control the switching element on/off to output a potential of any one input terminal from the output terminal.

Description

  The present invention relates to a multi-level power converter that generates an AC output converted from a DC voltage source into a plurality of voltage levels.

  As a conventional multilevel power converter, for example, a 5-level inverter described in Patent Document 1 is known. FIG. 16 is a circuit diagram showing a configuration of one phase of the main circuit in the 5-level inverter described in Patent Document 1. In FIG. 16, C1 and C2 are DC capacitors, C3 and C4 are flying capacitors, and S is a switching element (a module in which a diode is connected in antiparallel with a semiconductor switching element such as an IGBT: the same applies hereinafter).

  In the five-level inverter shown in FIG. 16, each switching element S is turned on and off, and the voltages Vc1, Vc2, Vc3, Vc4 of the DC capacitors C1, C2, and the flying capacitors C3, C4 are expressed as Vc1 = Vc2 = 1 / 2E. By controlling so that Vc3 = Vc4 = 1 / 4E, a five-level phase voltage as shown in FIG. 17 can be output between the terminals RO.

  A technique regarding voltage control of a DC capacitor is described in Patent Document 2, and a technique regarding voltage control of a flying capacitor is described in Patent Document 3.

Japanese Patent No. 4369425 Japanese Unexamined Patent Publication No. 7-75345 Japanese Patent No. 3301761

  The multi-level power conversion device shown in FIG. 16 can output a five-level phase voltage, and is composed of two flying capacitors C3 and C4 and ten switching elements S per phase. In the case of three phases, three sets of the five-level power converter shown in FIG. 16 are required, and six flying capacitors and thirty switching elements are used.

  As described above, the conventional multi-level power conversion device has a problem that the number of flying capacitors is large and the device becomes large.

  As described above, in the multilevel power conversion device, it is a problem to reduce the number of flying capacitors and to reduce the size of the device.

  The present invention has been devised in view of the above-described conventional problems, and one aspect thereof is a multi-level power converter that generates an AC output converted from a voltage of a DC voltage source into a plurality of voltage levels, A basic circuit having N (N ≧ 2) first basic cells in which switching elements, flying capacitors, and switching elements are sequentially connected in series between the positive and negative electrodes of N DC voltage sources connected in series; In addition, a switching element, a flying capacitor, and a second basic cell in which switching elements are sequentially connected in series are connected in parallel to the flying capacitor in each of the first basic cells. An extension circuit in which two basic cells are connected in parallel and this is repeated K times to connect K (K ≧ 1) second basic cells; By using both terminals of the flying capacitor of the second basic cell at the Kth as input terminals and switching elements between the input terminals and the output terminals, and selectively switching these switching elements on and off, And an M-phase (M ≧ 3) voltage selection circuit for outputting the potential of any one of the input terminals from the output terminal.

  Another aspect is a multi-level power converter that generates an AC output converted from a voltage of a DC voltage source into a plurality of voltage levels, between each positive and negative electrode of N DC voltage sources connected in series. Further, a switching circuit, a flying capacitor, a basic circuit having N (N ≧ 2) first basic cells each having a switching element connected in series, and both ends of the flying capacitors of the first basic cells are input terminals. And having a switching element between each of the input terminals and the output terminal, and by selectively turning on and off the switching element, the potential of any one of the input terminals is selected as an output terminal. And an M-phase (M ≧ 3) voltage selection circuit for outputting from

  Furthermore, another aspect is a multi-level power converter that generates an AC output converted from a voltage of a DC voltage source into a plurality of voltage levels, between each positive and negative electrode of N DC voltage sources connected in series. In addition, a switching circuit, a flying capacitor, a basic circuit having N (N ≧ 2) first basic cells each having a switching element connected in series, both end terminals of the flying capacitors of the first basic cells, By using all or any one of both terminals of the DC voltage source as an input terminal and having a switching element between each of the input terminals and the output terminal, and selectively switching the switching elements ON and OFF, And an M-phase (M ≧ 3) voltage selection circuit for outputting the potential of any one of the input terminals from the output terminal.

  The basic circuit may include a switching element between one of both terminals of the flying capacitor of each first basic cell and the input terminal of the voltage selection circuit.

  The voltage selection circuit has a common connection point between both terminals of the flying capacitor of each first basic cell and each DC voltage source as an input terminal, and switches between each common connection point and the output terminal of the voltage selection circuit. The element may be a bidirectional switch that can be controlled in the reverse withstand voltage directions.

  The voltage selection circuit has, as input terminals, both ends of a series circuit in which both ends of the flying capacitor of each first basic cell and each DC voltage source are connected in series, and the flying capacitor of the first basic cell among the input terminals. The switching element connected to the both end terminals may be a bidirectional switch that can be controlled in the reverse breakdown voltage direction.

  In addition, some or all of the switching elements in the basic circuit, the voltage selection circuit, or the extension circuit may have a series number of two or more.

  Further, a part or all of the switching elements in the basic circuit, the voltage selection circuit, or the extension circuit may have a parallel number of two or more.

  ADVANTAGE OF THE INVENTION According to this invention, in a multilevel power converter device, it becomes possible to reduce the number of flying capacitors and to achieve size reduction of the device.

It is a circuit diagram which shows the basic cell in this invention. It is a circuit diagram which shows the basic circuit in this invention. It is a circuit diagram which shows the expansion circuit in this invention. It is a circuit diagram which shows the voltage selection circuit in this invention. 1 is a circuit diagram illustrating a multilevel power conversion device according to Embodiment 1. FIG. It is a circuit diagram which shows the multilevel power converter device in Embodiment 2. It is a circuit diagram which shows the multilevel power converter device in Embodiment 3. It is a circuit diagram which shows the multilevel power converter device in Embodiment 4. FIG. 6 is a schematic diagram illustrating a switching pattern of a basic circuit portion and potentials output to terminals in Embodiment 4. FIG. 10 is a circuit diagram illustrating a multilevel power conversion device according to a fifth embodiment. It is a circuit diagram which shows the multilevel power converter device in Embodiment 6. It is a circuit diagram which shows the multilevel power converter device in Embodiment 7. FIG. 10 is a circuit diagram illustrating a multilevel power conversion device according to an eighth embodiment. FIG. 10 is a circuit diagram illustrating a multilevel power conversion device according to a ninth embodiment. It is a circuit diagram which shows the multilevel power converter device in Embodiment 10. FIG. FIG. 11 is a circuit diagram showing a 5-level inverter in Patent Document 1. It is a time chart which shows an example of the output phase voltage in a 5-level inverter.

[Basic configuration]
FIG. 1 is a circuit diagram showing a basic cell 1 used in a multilevel power conversion device according to the present invention. The basic cell 1 includes one flying capacitor and two switching elements (for example, IGBT: hereinafter the same).

Specifically, as shown in FIG. 1, the basic cell 1 is constructed by sequentially connecting a switching element S _1,1 , a flying capacitor C _FC1 , and a switching element S _1,2 between terminals 1 and 3. . Further, both terminals of the flying capacitor C _FC1 are terminals 2 and 2 ′.

  The terminal 1 is connected to the negative side of the DC voltage source, and the terminal 3 is connected to the positive side of the DC voltage source. Examples of the DC voltage source include a DC capacitor and a DC power source.

In the basic cell 1 shown in FIG. 1, when the switching element S _1,2 is ON and the switching element S _1,1 is OFF, the terminal 2 'outputs the potential of the terminal 3, and the terminal 2 outputs the flying capacitor from the potential of the terminal 3. C Outputs the potential obtained by subtracting the voltage of _FC1 .

Similarly, when the switching element S _1,1 is ON and the switching element S _1,2 is OFF, the terminal 2 outputs the potential of the terminal 1, and the terminal 2 ′ adds the voltage of the flying capacitor C _FC1 from the potential of the terminal 1. Output the selected potential.

  FIG. 2 is a circuit diagram showing a configuration of a basic circuit 2 in which N basic cells 1 shown in FIG. 1 are connected in series. Here, N ≧ 2. Further, the negative side of each DC voltage source is connected to terminals 1,..., 2N−1, and the positive side of each DC voltage source is connected to 3,.

Here, _{assuming that} the voltage of each DC voltage source is 2E and the voltage of each flying capacitor C _FC1 ... C _FCN is E, the terminal 2p (p = 1,. A voltage of (p-1) or 2Ep-E is output, and a voltage of 2Ep or 2Ep-E can be output to the terminal 2p ′ (p = 1,..., N).

As a result, the basic circuit 2 shown in FIG. 2 selectively turns on and off the switching elements S _1,1 , S _1,2 ,..., S _{N, 1} , S _{N, 2} , thereby causing the terminals 2, 2 ′,. , 2N, 2N ′ to 2N + 1 level potential.

FIG. 3 is a circuit diagram showing an expansion circuit 3 in which K basic cells 1 shown in FIG. 1 are connected. As shown in FIG. 3, the expansion circuit 3 connects both ends of the second basic cell 1 in parallel to the flying capacitor C1 in the first basic cell 1, and further, the flying capacitor in the second basic cell. Both ends of the third basic cell are connected to C2, and this is repeated to connect K (K ≧ 1) basic cells. The two terminals of the first basic cell are input terminals 2N_1 ′ and 2N_1, and both ends of the flying capacitor CK in the Kth basic cell are output terminals 2N_2 ′ and 2N_2. Further, the voltages of the flying capacitors are set to different values (for example, C1 = E, C2 = E / 2, CK = E / 2 ^K ).

  The switching element in the extension circuit 3 is selectively turned on and off to determine the current path, and the value obtained by adding or subtracting the voltage of the flying capacitor in the current path becomes the voltage level of the output terminals 2N_2 'and 2N_2. With this expansion circuit, the number of output voltage levels can be expanded.

  Next, the voltage selection circuit will be described with reference to FIG. The voltage selection circuit uses the terminals (2, 2 ′,..., 2N, 2N ′) of the basic circuit 2 or the terminals (2_2, 2_2 ′,..., 2N_2, 2N_2 ′) of the expansion circuit 3 as input terminals. The potential to be output from the output terminal is selected. The voltage selection circuit is configured by (a), (b), (c) in FIG. 4 or a combination of these circuits. Switching elements are provided between the input terminals and the output terminals. By selectively turning on the switching elements, the input terminals (2_3, 2_3 ′, 4_3, 4_3 ′,. , 2 (N-1) _3, 2 (N-1) 3 ', 2N_3, 2N_3', and (c), 2_3, 2_3 ', 4_3, 4_3', 6_3, 6_3 ') Can be output.

[Embodiment 1]
FIG. 5 is a schematic diagram illustrating a configuration of the multilevel power conversion device according to the first embodiment. As shown in FIG. 5, the multilevel power conversion device according to the first embodiment is an M-phase N configured using the basic circuit shown in FIG. 2, the extension circuit shown in FIG. 3, and the voltage selection circuit shown in FIG. 4. It is a multi-level power conversion device of stage K stage. Here, M represents the number of phases.

Since the configuration of the basic circuit 2 is the same as that of FIG. 2, the description thereof is omitted here. N DC voltage sources (DC capacitors C _{DC1 to} C _DCN ) are connected in series between both terminals 1 and 2N + 1 of the basic circuit 2, and each of terminals 3, 5,. A common connection point of DC capacitors C _DC1 , C _DC2 , C _DC3 ,..., C _DCN is connected.

  The phase modules 41, 42,..., 4M are connected to the terminals 2, 2 ', ..., 2N, 2N' of the basic circuit. Each of the phase modules 41, 42,..., 4M includes an expansion circuit 3 and a voltage selection circuit 5. The extension circuit 3 is provided in the same number as the basic cells in the basic circuit 2, and the basic circuit terminals 2, 2 ', ..., 2N, 2N' and the extension circuit input terminals 2_1, 2_1 ', ..., 2N_1, 2N_1'. And are connected. Further, the output terminals 2_2, 2_2 ',..., 2N_2, 2N_2' of the expansion circuit 3 and the input terminals 2_3, 2_3 ', ..., 2N_3, 2N_3' of the voltage selection circuit 41 are connected. And the output terminals of the voltage selection circuit 5 in the phase modules 41, 42,..., 4M become the output terminals OUT_1, OUT_2,.

Here, when the voltages of the DC capacitors C _DC1 and C _DCN are set to 2E and the voltages of the flying capacitors C _{FC1 to} C _{FCN in} the basic circuit 2 are controlled to E, the terminals 2,..., 2 (N− 1), 2N can output the voltage of (2p-2) E or (2p-1) E with respect to the potential of the terminal 1, respectively, and the terminals 2 ', ..., 2 (N-1)', 2N ' Can output a voltage of 2pE or (2p-1) E (p = 1,..., N).

  Next, the voltages output from the terminals 2, 2 ', 4, 4', ..., 2N, 2N 'are input to the phase modules 41, 42, ..., 4M, respectively. The voltages output from the terminals 2, 2 ', 4, 4', ..., 2N, 2N 'are first input to the expansion circuit 3.

Then, by controlling the voltage of the flying capacitors Cn (n = 1,..., K) in the expansion circuit 3 to E × (1/2) ⁿ , the output terminals 2_2, 2_2 ′,. , 2N_2 ′, a voltage of (2N · 2 ^K +1) level can be output.

Then, the voltage selection circuit 5 for each phase selects the switching elements and turns them on to select one of the input terminals 2_3, 2_3 ′,..., 2N_3, 2N_3 ′, and outputs the output terminals OUT_1, OUT_2,. Output from. As a result, it is possible to select and output any voltage level among the (2N · 2 ^K +1) levels from the output terminals OUT_1, OUT_2,..., OUT_M.

As described above, according to the multilevel power conversion device of the first embodiment, since the flying capacitors C _FC1 , C _FC2 ,..., C _FCN are shared by the M phase, the number of flying capacitors can be reduced. Can do. As a result, it is possible to reduce the size of the apparatus.

In addition, N basic cells are connected in series to form the basic circuit 2, and the number of voltage levels that can be output is increased by connecting the expansion circuit 3 to the K stage to select the voltage to be output in the voltage selection circuit 5. By doing so, it becomes possible to output a phase voltage of 2N · 2 ^K +1 level.

That is, according to the first embodiment, it is possible to realize an M-phase 2N · 2 ^K +1 level power converter with N + N · M · K flying capacitors.

[Embodiment 2]
Next, the multilevel power conversion device according to the second embodiment will be described with reference to FIG. As shown in FIG. 6, the multilevel power conversion device according to the second embodiment has an M-phase N-stage configuration by omitting the expansion circuit of the M-phase N-stage K-stage multilevel power conversion device according to the first embodiment. Is. That is, in the multilevel power conversion device according to the first embodiment, K = 0. Other configurations are the same as those of the first embodiment.

  The multilevel power conversion device according to the second embodiment can output a phase voltage of 2N + 1 level from terminals 2, 2 ', ..., 2N, 2N' by connecting N basic circuits in series. Further, by selectively turning ON / OFF the switching elements of the voltage selection circuit in each phase module 41, 42, 4M, one of the potentials of the terminals 2, 2 ′,..., 2N, 2N ′ is selected. And output from the output terminals OUT_1 to OUT_M.

  As a result, in the multilevel power conversion device according to the second embodiment, any one of the (2N + 1) levels can be selected and output from the output terminals OUT_1 to OUT_M.

Further, according to the multilevel power conversion device of the second embodiment, since the flying capacitors C _FC1 , C _FC2 ,..., C _FCN are shared by the M phase, the number of flying capacitors can be reduced. As a result, it is possible to reduce the size of the apparatus.

  That is, an M-phase 2N + 1 level power conversion device can be realized with N flying capacitors.

[Embodiment 3]
Next, the multilevel power conversion device according to the third embodiment will be described with reference to FIG. As shown in FIG. 7, the multi-level power converter in Embodiment 3, for multi-level power converter in Embodiment 2, the DC capacitor C _DC1, ..., C _DCN across terminals 1 and 3, ... , 2N-1, 2N + 1 are redundantly connected to the phase modules 41, 42,..., 4M of the respective phases.

That is, in the embodiment 2, the flying capacitor C _FC1, C _FC2, ..., both end terminals 2,2 _{C FCN ', ..., 2N,} 2N' only phase module 41, ..., and was connected to 4M, In the third embodiment, in addition to both end terminals 2, 2 ', ..., 2N, 2N' of the flying capacitors _CFC1 , _CFC2 , ..., _CFCN , both end terminals of the DC capacitors _CDC1 , ..., _CDCN 1, 3,..., 2N−1, 2N + 1 are also connected to the phase modules 41, 42,.

In this way, the terminals 1, 3,..., 2N-1, 2N + 1 of the DC capacitors C _DC1 ,..., C _DCN are also connected to the phase modules 41, 42,. The number of terminals that can be selected increases redundantly. That is, in the second embodiment, in the voltage selection circuit for each phase, one of the potentials of the two terminals 2, 2 ′,..., 2N, 2N ′ of each flying capacitor C _{FC1 ,.} Although output is performed from OUT_1 to OUT_M, in the third embodiment, in the voltage selection circuit of each phase, both terminals 2, 2 ′,..., 2N, 2N ′ of the flying capacitors C _FC1 , C _{FC2 ,.} In addition, the potentials of the terminals 1, 3,..., 2N-1, 2N + 1 of the DC capacitors C _DC1 ,..., C _DCN can also be selected and output from the output terminals OUT_1 to OUT_M.

Incidentally, the DC capacitor C _DC1 7, ..., both end terminals 1,3 of C _DCN, ..., connection lines between 2N-1, 2n + 1 and each phase module _{41~4M L 1, L 3, ...} , L 2N- ₁ and L _{2N + 1} are all connected, but not necessarily all connected.

  As described above, according to the multilevel power conversion device of the third embodiment, the same operational effects as those of the second embodiment can be obtained.

  Further, by connecting the both ends of the DC voltage source and the voltage selection circuit, the number of voltage level patterns that can be selected in the voltage selection circuit is increased as compared with the second embodiment.

[Embodiment 4]
(1) Circuit Configuration Next, the multilevel power conversion device according to the fourth embodiment will be described with reference to FIGS. In the multilevel power conversion device according to the fourth embodiment, N = 2 and M = 3 in the multilevel power conversion circuit according to the second embodiment.

Specifically, a basic circuit is configured by connecting two basic cells in series. DC capacitors C _DC1 and C _DC2 are connected in series between terminals 1 and 5 of the basic circuit, and a common connection point of DC capacitors C _DC1 and C _DC2 is connected to terminal 3 of the basic circuit. The basic circuit is connected to U-phase, V-phase, and W-phase voltage selection circuits.

In the voltage selection circuit, the U-phase, across terminals 4 of the flying capacitor C _FC2 ', the switching element SU5, SU6 are connected in series between the 4, both ends terminal 2 of the flying capacitor C _FC1', the switching element between 2 SU7, Su8 Are connected in series. The switching elements Su9 and Su10 are connected in series between the common connection point of the switching elements Su5 and Su6 and the common connection point of the switching elements Su7 and Su8. A common connection point between the switching element Su9 and the switching element Su10 is a U-phase output terminal OUT_U. Similarly, a voltage selection circuit is configured for the V phase and the W phase.

(2) Generation of Switching Pattern of Multilevel Power Conversion Device Here, the operation of the multilevel power conversion device in Embodiment 4 will be described.

FIG. 9 is a schematic diagram showing the switching pattern of the basic circuit portion and the potentials output to the terminals 4 ′, 4, 2 ′, 2 of the flying capacitors C _FC2 , C _FC1 . Here, the voltages of the DC capacitors C _DC1 and C _DC2 are controlled to 2E, and the voltages of the flying capacitors C _FC1 and C _FC2 are controlled to E. The reference point of the potential is the terminal 3 that is a common connection point of the DC capacitors C _DC1 and C _DC2 .

Table 1 shows the states of the switching elements S _1,1 , S _1,2 , S _2,1 , S _2,2 and the potentials of the terminals 2, 2 ′, 4, 4 ′ in the patterns 1 to 4. . In Table 1, when S _1,1 : OFF and S _1,2 : ON, S _1,1 (/ S _1.2 ) = 0, S _1,1 : ON, S _1,2 : OFF In this case, S _1,1 (/ S _1.2 ) = 1. The same applies to S _2,1 (/ S _2,2 ).

[Pattern 1] S _2,2 : ON, S _2,1 : OFF, S _1,2 : ON, S _1,1 : OFF
The terminal 4 'is 2E, the terminal 4 is E, the terminal 2' is 0, and the terminal 2 is -E.

[Pattern 2] S _2,2 : ON, S _2,1 : OFF, S _1,2 : OFF, S _1,1 : ON
Terminal 4 'is 2E, terminal 4 is E, terminal 2' is -E, and terminal 2 is -2E.

[Pattern 3] S _2,2 : OFF, S _2,1 : ON, S _1,2 : ON, S _1,1 : OFF
The terminal 4 'is E, the terminal 4 is 0, the terminal 2' is 0, and the terminal 2 is -E.

[Pattern 4] S _2,2 : OFF, S _2,1 : ON, S _1,2 : OFF, S _1,1 : ON
Terminal 4 'is at E, terminal 4 is at 0, terminal 2' is at -E, and terminal 2 is at -2E.

As described above, from pattern 1 to pattern 4, the terminal 4 ′ has a potential of 2E or E, the terminal 4 has a potential of E or 0, the terminal 2 ′ has a potential of 0 or −E, and the terminal 2 Can output a potential of -E or -2E. That is, by selectively turning on and off the switching elements S _1.1 , S _1.2 , S _2.1 , and S _2.2 , the terminals 2, 2 ′, 4, 4 ′ to −2E, −E, 0, E, 2E 5 A level potential can be output.

  Therefore, by selecting any one of the terminal potentials 4, 4 ′, 2, 2 ′ with the voltage selection circuit, the voltage of 5 levels of 2E, E, 0, −E, −2E is output to the output terminals OUT_U, It is possible to output from OUT_V and OUT_W.

  For example, in the U-phase voltage selection circuit, the potential of the terminal 2 can be output from the output terminal OUT_U by turning on the switching elements Su8 and Su10 and turning off the other switching elements. Similarly, by turning on the switching elements Su7 and Su10, the potential of the terminal 2 ′ is output from the output terminal OUT_U, and by turning on the switching elements Su6 and Su9, the potential of the terminal 4 is output from the output terminal OUT_U. By turning on the switching elements Su5 and Su9, the potential of the terminal 4 ′ can be output from the output terminal OUT_U. The same applies to the V phase and the W phase.

As described above, according to the multilevel power conversion device of the fourth embodiment, the flying capacitors C _FC1 and C _FC2 are shared by three phases, and the three-phase five-level power conversion device is composed of two flying capacitors. Can be realized. When comparing the number of flying capacitors and the 5-level power converter of Patent Document 1 shown in FIG. 16, the total of three phases in Patent Document 1 is six, whereas the total of three phases in Embodiment 4 is two. Therefore, the number of flying capacitors can be reduced. As a result, it is possible to reduce the size of the apparatus.

  The patterns 1 to 4 do not have a pattern for simultaneously outputting the potentials 2E, 0, and -2E from the terminals 4 ', 4, 2', and 2 of the flying capacitor. Therefore, the combination potentials shown in Table 2 cannot be output simultaneously from the output terminals OUT_U, OUT_V, and OUT_W shown in FIG.

  Therefore, in the multilevel power conversion device according to the fourth embodiment, it is necessary to control the switching elements in the U-phase, V-phase, and W-phase voltage selection circuits in consideration of the combination of potentials that cannot be output. , V phase and W phase cannot be controlled independently in each phase.

  Further, the circuit shown in FIG. 8 is an example, and may be a circuit in which each switching element is two or more series in order to increase the voltage, or may be a circuit in which each switching element is two or more in parallel to increase current.

[Embodiment 5]
Next, the multilevel power conversion device according to the fifth embodiment will be described with reference to FIG. The multilevel power conversion device according to the fifth embodiment has a configuration in which switching elements _{Sn, 3} are inserted between terminals 2n and 2n ′ of each basic cell with respect to the multilevel power conversion device according to the fourth embodiment. In other words, the switching element _Sn.3 is inserted between one of both end terminals of the flying capacitor C _FCn and the input terminal of the voltage selection circuit.

In Embodiment 5, the switching element S _{1, 3} is interposed between the flying capacitor C _FC1 and terminal 2 ', the switching element S _2,3 is interposed between the terminal 4 and the flying capacitor C _FC2 ing. Other configurations are the same as those of the fourth embodiment.

By the added switching elements S _1,3 and S _2,3 , the number of potential patterns that can be output from the terminals 4 ′, 4, 2 ′, and 2 increases.

A specific example will be described. First, the voltages of the DC capacitors C _DC1 and C _DC2 are controlled to 2E, and the voltages of the flying capacitors C _FC1 and C _FC2 are controlled to E. The reference point of the potential is the terminal 3 that is a common connection point of the DC capacitors C _DC1 and C _DC2 .

For example, the switching element _{S 2,2: ON, S 2,3:} OFF, S 2,1: ON, S 1,2: ON, S 1,3: OFF, S 1,1: When turned ON, the terminals Is 4 ′: 2E, 4: 0, 2: 0 ′, and 2: −2E. That is, the potential at the common connection point of the DC capacitors C _DC1 and C _DC2 (that is, the terminal 3) can be output to the terminals 4 ′, 4, 2 ′, and 2 simultaneously with the potentials of the terminals 5 and 1. By selecting the potentials 2E, 0, and -2E output from the terminals 4 ′, 4, 2 ′, and 2 by turning on and off the switching elements of the voltage selection circuit, the potentials that were not in the fourth embodiment ( 2E, 0, -2E) can be output simultaneously from the output terminals OUT_U, OUT_V, OUT_W.

  Therefore, in the fifth embodiment, three-phase output in all combinations of 2E, E, 0, -E, and -2E is possible, and each phase of the U phase, the V phase, and the W phase that cannot be achieved in the fourth embodiment. Thus, the voltage selection circuit can be controlled independently.

  Further, as in the fourth embodiment, the three-phase five-level power conversion device can be realized with two flying capacitors, and thus the device can be downsized.

[Embodiment 6]
Next, the multilevel power conversion device according to the sixth embodiment will be described with reference to FIG.

  The multilevel power conversion device according to the sixth embodiment is opposite to the voltage selection circuit of the multilevel power conversion device according to the fourth embodiment between the output terminals OUT_U, OUT_V, OUT_W and the terminals 3 of the respective phases. A bidirectional switch that can be controlled in the withstand voltage direction is inserted. There are several ways to configure the bidirectional switch. FIG. 11 shows a bidirectional switch having a configuration in which the switching elements Su11 and Su12 are connected in series in the reverse direction. The same applies to the V phase and the W phase.

  In this configuration, in the multilevel power conversion device according to the third embodiment, M = 3 and N = 2, the connection lines L1 and L5 to the voltage selection circuit of each phase are not connected, and the connection line L3 is connected. Corresponds to the configuration.

In this way, by connecting the terminal 3, that is, the common connection point of the DC capacitors C _DC1 and C _DC2 and the output terminals OUT_U, OUT_V, and OUT_W with the bidirectional switches, 2E, 0, − as in the fifth embodiment. 2E simultaneous output patterns are possible. As a result, the potential pattern output from the basic circuit is increased as compared with the fourth embodiment.

For example, the operation when OUT_U = 0, OUT_V = 2E, and OUT_W = −2E are output from the output terminal will be described. Here, as in the fifth embodiment, the voltages of the DC capacitors C _DC1 and C _DC2 are controlled to 2E, and the voltages of the flying capacitors C _FC1 and C _FC2 are controlled to E. The reference point of the potential is the terminal 3 that is a common connection point of the DC capacitors C _DC1 and C _DC2 .

[S _2,2 : ON, S _2,1 : OFF, S _1,2 : OFF, S _1,1 : ON]
In such a case, the potential of each terminal is 4 ': 2E, 4: E, 3: 0, 2':-E, 2: -2E. Further, by turning on the switching elements Su11, Su12, Sv5, Sv9, Sw8, and Sw10 and turning off the other switching elements, OUT_U = 0, OUT_V = 2E, and OUT_W = −2E are output at each output terminal. Is possible.

  In addition to the above, by changing the switching pattern of the voltage selection circuit, it is possible to simultaneously output other combinations of 2E, 0, and 2E potentials from the output terminals OUT_U, OUT_V, and OUT_W (for example, OUT_U = 2E, OUT_V = 0, OUT_W = -2E).

  Therefore, in the sixth embodiment, three-phase output is possible with all combinations of (2E, E, 0, -E, -2E), and the U-phase, V-phase, and W-phase that could not be achieved in the fourth embodiment. The voltage selection circuit can be controlled independently for each phase.

  Further, since the three-phase five-level power conversion device can be realized with two flying capacitors as in the fourth embodiment, the size of the device can be reduced.

[Embodiment 7]
(1) Circuit Configuration Next, a multi (7) level power converter according to the seventh embodiment will be described with reference to FIG.

  The multi- (7) level power converter according to the seventh embodiment has a configuration in which N = 3 and M = 3 with respect to the multi-level power converter according to the second embodiment, and outputs a 7-level phase voltage. It is.

Specifically, the basic circuit is configured by connecting the three basic cells in series. DC capacitors C _DC1 , C _DC2 , C _DC3 are connected in series between terminals 1 and 7 of the basic circuit, and a common connection point of DC capacitors C _DC1 , C _DC2 is connected to terminal 3 of the basic circuit, and DC capacitor C _DC2 , C _DC3 common connection point is connected to terminal 5 of the basic circuit.

  The basic circuit is connected to U-phase, V-phase, and W-phase voltage selection circuits. In the U phase, the switching elements Su13 and Su14 are connected in series between the terminal 6 ′ and the terminal 6 of the basic circuit, the switching elements Su15 and Su16 are connected in series between the terminal 4 ′ and the terminal 4, and the terminal 2 ′. Are connected in series between the switching elements Su17 and Su18. The switching elements Su19, Su20, Su21, and Su22 are connected in series between the common connection point of the switching elements Su13 and Su14 and the common connection point of the switching elements Su17 and Su18. Furthermore, diodes Du1 and Du2 are interposed between the common connection point of the switching elements Su19 and Su20 and the common connection point of the switching elements Su21 and Su22. The common connection point of the diodes Du1 and Du2 and the switching elements Su15 and Su16 To the common connection point. The common connection point between the switching elements Su20 and Su21 is the U-phase output terminal OUT_U. Similarly, a voltage selection circuit is configured for the V phase and the W phase.

(2) Generation of switching pattern of multilevel power conversion device The operation of the multilevel power conversion device according to the seventh embodiment will be described. Here, the voltages of the DC capacitors C _DC1 , C _DC2 and C _DC3 are controlled to 2E, and the voltages of the flying capacitors C _FC1 , C _FC2 and C _FC3 are controlled to E. Note that the reference point of the potential is the terminal 1.

Further, the states of the switching elements S _1.1 , S _1.2 , S _2.1 , S _2.2 , S _3.1 , S _3.2 and the potentials of the terminals 2, 2 ′, 4, 4 ′, 6, 6 ′ in each pattern in the basic circuit are shown. 3 shows. In Table 3, when S _1,1 : OFF and S _1,2 : ON, S _1,1 (/ S _1.2 ) = 0, S _1,1 : ON, S _1,2 : OFF In this case, S _1,1 (/ S _1.2 ) = 1. The same applies to S _2,1 (/ S _2,2 ) and S _3,1 (/ S _3,2 ).

[Pattern 1] S _1,1 : OFF, S _1,2 : ON, S _2,1 : OFF, S _2,2 : ON, S _3,1 : OFF, S _3,2 : ON
Terminal 2 is at E, terminal 2 'is at 2E, terminal 4 is at 3E, terminal 4' is at 4E, terminal 6 is at 5E, and terminal 6 'is at 6E.

[Pattern 2] S _1,1 : OFF, S _1,2 : ON, S _2,1 : ON, S _2,2 : OFF, S _3,1 : OFF, S _3,2 : ON
Terminal 2 is at E, terminal 2 'is at 2E, terminal 4 is at 2E, terminal 4' is at 3E, terminal 6 is at 5E, and terminal 6 'is at 6E.

[Pattern 3] S _1,1 : OFF, S _1,2 : ON, S _2,1 : OFF, S _2,2 : ON, S _3,1 : ON, S _3,2 : OFF
Terminal 2 is at E, terminal 2 'is at 2E, terminal 4 is at 3E, terminal 4' is at 4E, terminal 6 is at 4E, and terminal 6 'is at 5E.

[Pattern 4] S _1,1 : OFF, S _1,2 : ON, S _2,1 : ON, S _2,2 : OFF, S _3,1 : ON, S _3,2 : OFF
Terminal 2 is at E, terminal 2 'is at 2E, terminal 4 is at 2E, terminal 4' is at 3E, terminal 6 is at 4E, and terminal 6 'is at 5E.

[Pattern 5] S _1,1 : ON, S _1,2 : OFF, S _2,1 : OFF, S _2,2 : ON, S _3,1 : OFF, S _3,2 : ON
Terminal 2 is at 0, terminal 2 'is at E, terminal 4 is at 3E, terminal 4' is at 4E, terminal 6 is at 5E, and terminal 6 'is at 6E.

[Pattern 6] S _1,1 : ON, S _1,2 : OFF, S _2,1 : ON, S _2,2 : OFF, S _3,1 : OFF, S _3,2 : ON
Terminal 2 is at 0, terminal 2 'is at E, terminal 4 is at 2E, terminal 4' is at 3E, terminal 6 is at 5E, and terminal 6 'is at 6E.

[Pattern 7] S _1,1 : ON, S _1,2 : OFF, S _2,1 : OFF, S _2,2 : ON, S _3,1 : ON, S _3,2 : OFF
Terminal 2 is at 0, terminal 2 'is at E, terminal 4 is at 3E, terminal 4' is at 4E, terminal 6 is at 4E, and terminal 6 'is at 5E.

[Pattern 8] S _1,1 : ON, S _1,2 : OFF, S _2,1 : ON, S _2,2 : OFF, S _3,1 : ON, S _3,2 : OFF
Terminal 2 is at 0, terminal 2 'is at E, terminal 4 is at 2E, terminal 4' is at 3E, terminal 6 is at 4E, and terminal 6 'is at 5E.

  As described above, from pattern 1 to pattern 8, the terminal 2 has a potential of 0 or E, the terminal 2 ′ has a potential of 2E or E, the terminal 4 has a potential of 2E or 3E, and the terminal 4 ′. Can output a 3E or 4E potential, a terminal 6 can output a 4E or 5E potential, and a terminal 6 'can output a 5E or 6E potential. Therefore, by selecting any one of the terminals 2, 2 ', 4, 4', 6, 6 'by the voltage selection circuit, the seven-level potentials of 0, E, 2E, 3E, 4E, 5E, 6E are obtained. It is possible to output from the output terminals OUT_U, OUT_V, OUT_W.

  For example, by turning on Su13, Su19, Su20 among the switching elements in the U-phase voltage selection circuit and turning off the other switching elements, the potential of the terminal 6 ′ can be output from the U-phase output terminal OUT_U. it can. Further, by selecting the switching element of the voltage selection circuit and turning it ON, the potentials of the other terminals (6, 4 ', 4, 2', 2) can be output from the U-phase output terminal OUT_U. The same applies to the V phase and the W phase.

As described above, according to the multi- (7) level power converter in the seventh embodiment, the flying capacitors C _FC1 , C _FC2 , and C _FC3 are shared by the three phases, and the three-phase seven-level power converter is provided. Can be realized with three flying capacitors. Therefore, the number of flying capacitors can be reduced, and the device can be miniaturized.

[Eighth embodiment]
Next, the multilevel power conversion device according to the eighth embodiment will be described with reference to FIG.

  The multilevel power conversion device according to the eighth embodiment has a configuration in which N = 4 and M = 3 with respect to the multilevel power conversion device according to the second embodiment.

Specifically, the basic circuit is configured by connecting the four basic cells in series. Between the terminals 1 and 9 of the basic circuit, DC capacitors C _DC1 , C _DC2 , C _DC3 , and C _DC4 are sequentially connected in series, and the common connection point of the DC capacitors C _DC1 and C _DC2 is connected to the terminal 3 of the basic circuit. A common connection point of the DC capacitors C _DC2 and C _DC3 is connected to the terminal 5 of the basic circuit, and a common connection point of the DC capacitors C _DC3 and C _DC4 is connected to the terminal 7 of the basic circuit.

  The basic circuit is connected to U-phase, V-phase, and W-phase voltage selection circuits.

  In the voltage selection circuit, switching elements Su23 and Su24 are connected in series between the terminal 8 ′ and the terminal 8 of the basic circuit in the U phase, and switching elements Su25 and Su26 are connected in series between the terminal 6 ′ and the terminal 6. The switching elements Su27 and Su28 are connected in series between the terminal 4 ′ and the terminal 4, and the switching elements Su29 and Su30 are connected in series between the terminal 2 ′ and the terminal 2. The switching elements Su31 and Su32 are connected in series between the common connection point of the switching elements Su23 and Su24 and the common connection point of the switching elements Su29 and Su30.

  Furthermore, a bidirectional switch in which the switching elements Su33 and Su34 are connected in series in the reverse direction is inserted between the common connection point of the switching elements Su25 and Su26 and the common connection point of the switching elements Su31 and Su32, and the switching elements Su27 and Su28. A bidirectional switch in which switching elements Su35 and Su36 are connected in series in the reverse direction is inserted between the common connection point of the switching elements Su31 and Su32. The common connection point between the switching elements Su31 and Su32 is a U-phase output terminal OUT_U. Similarly, a voltage selection circuit is configured for the V phase and the W phase.

(2) Generation of switching pattern of multilevel power conversion device The operation of the multilevel power conversion device according to the eighth embodiment will be described. Here, the voltages of the DC capacitors C _DC1 , C _DC2 , C _DC3 , and C _DC4 are controlled to 2E, and the voltages of the flying capacitors C _FC1 , C _FC2 , C _FC3 , and C _FC4 are controlled to E. Note that the reference point of the potential is the terminal 5.

In addition, the switching elements S _1.1 , S _1.2 , S _2.1 , S _2.2 , S _3.1 , S _3.2 , S _4.1 , S _4.2 in each pattern in the basic circuit and the terminals 2, 2 ′, 4, 4 ′, Table 4 shows the potentials of 6, 6 ′, 8, and 8 ′. In Table 4, when S _1,1 : OFF, S _1,2 : ON, S _1,1 (/ S _1.2 ) = 0, S _1,1 : ON, S _1,2 : OFF In this case, S _1,1 (/ S _1.2 ) = 1. The same applies to S _2,1 (/ S _2,2 ), S _3,1 (/ S _3,2 ), and S _4,1 (/ S _4,2 ).

[Pattern 1] S _1,1 : OFF, S _1,2 : ON, S _2,1 : OFF, S _2,2 : ON, S _3,1 : OFF, S _3,2 : ON, S _4,1 : OFF, S _4,2 : ON
Terminal 2 is at -3E, terminal 2 'is at -2E, terminal 4 is at -E, terminal 4' is at 0, terminal 6 is at E, terminal 6 'is at 2E, terminal 8 is at 3E, and terminal 8' is at 4E. .

[Pattern 2] S _1,1 : OFF, S _1,2 : ON, S _2,1 : OFF, S _2,2 : ON, S _3,1 : OFF, S _3,2 : ON, S _4,1 : ON, S _4,2 : OFF
Terminal 2 is at -3E, terminal 2 'is at -2E, terminal 4 is at -E, terminal 4' is at 0, terminal 6 is at E, terminal 6 'is at 2E, terminal 8 is at 2E, and terminal 8' is at 3E. .

[Pattern 3] S _1,1 : OFF, S _1,2 : ON, S _2,1 : OFF, S _2,2 : ON, S _3,1 : ON, S _3,2 : OFF, S _4,1 : OFF, S _4,2 : ON
Terminal 2 is at -3E, terminal 2 'is at -2E, terminal 4 is at -E, terminal 4' is at 0, terminal 6 is at 0, terminal 6 'is at E, terminal 8 is at 3E, and terminal 8' is at 4E. .

[Pattern 4] S _1,1 : OFF, S _1,2 : ON, S _2,1 : OFF, S _2,2 : ON, S _3,1 : ON, S _3,2 : OFF, S _4,1 : ON, S _4,2 : OFF
Terminal 2 is at -3E, terminal 2 'is at -2E, terminal 4 is at -E, terminal 4' is at 0, terminal 6 is at 0, terminal 6 'is at E, terminal 8 is at 2E, and terminal 8' is at 3E. .

[Pattern 5] S _1,1 : OFF, S _1,2 : ON, S _2,1 : ON, S _2,2 : OFF, S _3,1 : OFF, S _3,2 : ON, S _4,1 : OFF, S _4,2 : ON
Terminal 2 is −3E, terminal 2 ′ is −2E, terminal 4 is −2E, terminal 4 ′ is −E, terminal 6 is E, terminal 6 ′ is 2E, terminal 8 is 3E, and terminal 8 ′ is 4E. Become.

[Pattern 6] S _1,1 : OFF, S _1,2 : ON, S _2,1 : ON, S _2,2 : OFF, S _3,1 : OFF, S _3,2 : ON, S _4,1 : ON, S _4,2 : OFF
Terminal 2 is −3E, terminal 2 ′ is −2E, terminal 4 is −2E, terminal 4 ′ is −E, terminal 6 is E, terminal 6 ′ is 2E, terminal 8 is 2E, and terminal 8 ′ is 3E. Become.

[Pattern 7] S _1,1 : OFF, S _1,2 : ON, S _2,1 : ON, S _2,2 : OFF, S _3,1 : ON, S _3,2 : OFF, S _4,1 : OFF, S _4,2 : ON
Terminal 2 is −3E, terminal 2 ′ is −2E, terminal 4 is −2E, terminal 4 ′ is −E, terminal 6 is 0, terminal 6 ′ is E, terminal 8 is 3E, and terminal 8 ′ is 4E. Become.

[Pattern 8] S _1,1 : OFF, S _1,2 : ON, S _2,1 : ON, S _2,2 : OFF, S _3,1 : ON, S _3,2 : OFF, S _4,1 : ON, S _4,2 : OFF
Terminal 2 is −3E, terminal 2 ′ is −2E, terminal 4 is −2E, terminal 4 ′ is −E, terminal 6 is 0, terminal 6 ′ is E, terminal 8 is 2E, and terminal 8 ′ is 3E. Become.

[Pattern 9] S _1,1 : ON, S _1,2 : OFF, S _2,1 : OFF, S _2,2 : ON, S _3,1 : OFF, S _3,2 : ON, S _4,1 : OFF, S _4,2 : ON
Terminal 2 is at -4E, terminal 2 'is at -3E, terminal 4 is at -E, terminal 4' is at 0, terminal 6 is at E, terminal 6 'is at 2E, terminal 8 is at 3E, and terminal 8' is at 4E. .

[Pattern 10] S _1,1 : ON, S _1,2 : OFF, S _2,1 : OFF, S _2,2 : ON, S _3,1 : OFF, S _3,2 : ON, S _4,1 : ON, S _4,2 : OFF
Terminal 2 is at -4E, terminal 2 'is at -3E, terminal 4 is at -E, terminal 4' is at 0, terminal 6 is at E, terminal 6 'is at 2E, terminal 8 is at 2E, and terminal 8' is at 3E. .

[Pattern 11] S _1,1 : ON, S _1,2 : OFF, S _2,1 : OFF, S _2,2 : ON, S _3,1 : ON, S _3,2 : OFF, S _4,1 : OFF, S _4,2 : ON
Terminal 2 is at -4E, terminal 2 'is at -3E, terminal 4 is at -E, terminal 4' is at 0, terminal 6 is at E, terminal 6 'is at 2E, terminal 8 is at 3E, and terminal 8' is at 4E. .

[Pattern 12] S _1,1 : ON, S _1,2 : OFF, S _2,1 : OFF, S _2,2 : ON, S _3,1 : ON, S _3,2 : OFF, S _4,1 : ON, S _4,2 : OFF
Terminal 2 is at -4E, terminal 2 'is at -3E, terminal 4 is at -E, terminal 4' is at 0, terminal 6 is at 0, terminal 6 'is at E, terminal 8 is at 2E, and terminal 8' is at 3E. .

[Pattern 13] S _1,1 : ON, S _1,2 : OFF, S _2,1 : ON, S _2,2 : OFF, S _3,1 : OFF, S _3,2 : ON, S _4,1 : OFF, S _4,2 : ON
Terminal 2 is −4E, terminal 2 ′ is −3E, terminal 4 is −E, terminal 4 ′ is −E, terminal 6 is E, terminal 6 ′ is 2E, terminal 8 is 3E, and terminal 8 ′ is 4E. Become.

[Pattern 14] S _1,1 : ON, S _1,2 : OFF, S _2,1 : ON, S _2,2 : OFF, S _3,1 : OFF, S _3,2 : ON, S _4,1 : ON, S _4,2 : OFF
Terminal 2 is −4E, terminal 2 ′ is −3E, terminal 4 is −2E, terminal 4 ′ is −E, terminal 6 is E, terminal 6 ′ is 2E, terminal 8 is 2E, and terminal 8 ′ is 3E. Become.

[Pattern 15] S _1,1 : ON, S _1,2 : OFF, S _2,1 : ON, S _2,2 : OFF, S _3,1 : ON, S _3,2 : OFF, S _4,1 : OFF, S _4,2 : ON
Terminal 2 is −4E, terminal 2 ′ is −3E, terminal 4 is −2E, terminal 4 ′ is −E, terminal 6 is 0, terminal 6 ′ is E, terminal 8 is 3E, and terminal 8 ′ is 4E. Become.

[Pattern 16] S _1,1 : ON, S _1,2 : OFF, S _2,1 : ON, S _2,2 : OFF, S _3,1 : ON, S _3,2 : OFF, S _4,1 : ON, S _4,2 : OFF
Terminal 2 is −4E, terminal 2 ′ is −3E, terminal 4 is −2E, terminal 4 ′ is −E, terminal 6 is 0, terminal 6 ′ is E, terminal 8 is 2E, and terminal 8 ′ is 3E. Become.

  As described above, from pattern 1 to pattern 16, the terminal 2 has a potential of −3E or −4E, the terminal 2 ′ has a potential of −2E or −3E, and the terminal 4 has a potential of −E or −2E. Terminal 4 ', 0 or -E potential, terminal 6 0 or E potential, terminal 6' E or 2E potential, terminal 8 2E or 3E potential, A potential of 3E or 4E can be output to 8 ′. Therefore, by selecting any of the terminals 2, 2 ′, 4, 4 ′, 6, 6 ′, 8, 8 ′ by the voltage selection circuit, −4E, −3E, −2E, −E, 0, It is possible to output any one of the nine levels of E, 2E, 3E, and 4E to the output terminals OUT_U, OUT_V, and OUT_W.

  For example, by turning on Su23 and Su31 among the switching elements in the U-phase voltage selection circuit and turning off the other switching elements, the potential of the terminal 8 'can be output from the U-phase output terminal U_OUT. Further, by selecting the switching element of the voltage selection circuit and turning it on, the potentials of the other terminals (8, 6'6, 4 ', 4, 2', 2) can be output from the output terminal.

As described above, according to the multi- (9) level power converter in the eighth embodiment, the flying capacitors C _FC1 , C _FC2 , C _FC3 , and C _FC4 are shared by three phases, The power conversion device can be realized with four flying capacitors. Therefore, the number of flying capacitors can be reduced, and the device can be miniaturized.

[Embodiment 9]
Next, the multilevel power conversion device according to the ninth embodiment will be described with reference to FIG.

(1) Circuit Configuration The multilevel power conversion device according to the ninth embodiment is a basic circuit (N = 2) in which two basic cells are connected in series in the multilevel power conversion device according to the third embodiment. On the other hand, a three-phase voltage selection circuit is connected. Connection lines L1 and L5 are connected and L3 is not connected.

  In the voltage selection circuit, one end of a bidirectional switch in which two switching elements Su37 and Su38 are connected in series in the reverse direction is connected to the terminal 4 'in the U phase. Similarly, one end of a bidirectional switch composed of switching elements Su39 and Su40 is connected to the terminal 4, and one end of a bidirectional switch composed of switching elements Su41 and Su42 is connected to the terminal 2 ′. Terminal 2 is connected to one end of a bidirectional switch composed of switching elements Su43 and Su44.

  Further, switching elements Su45, Su46, Su47, and Su48 are connected in series between the terminal 5 and the terminal 1. The other end of the bidirectional switch composed of the switching elements Su37 and Su38 and the bidirectional switch composed of the switching elements Su39 and Su40 are connected to a common connection point of the switching elements Su45 and Su46, and the switching elements Su41 and Su42. The other end of the bidirectional switch configured by and the bidirectional switch configured by the switching elements Su43 and Su44 is connected to a common connection point of the switching elements Su47 and Su48.

  A common connection point between the switching elements Su46 and Su47 is a U-phase output terminal OUT_U. Similarly, a voltage selection circuit is configured for the V phase and the W phase.

(2) Switching pattern generation of multilevel power conversion device According to the multilevel power conversion device of the ninth embodiment, 2E, 0, and -2E simultaneous output patterns are possible as in the fifth and sixth embodiments.

As an example, an operation when outputting the output terminals OUT_U = 0, OUT_V = 2E, and OUT_W = −2E will be described. Note that the reference point of the potential is the terminal 3. Here, as in the fifth and sixth embodiments, the voltages of the DC capacitors C _DC1 and C _DC2 are controlled to 2E, and the voltages of the flying capacitors C _FC1 and C _FC2 are controlled to E.

When the switching element of the basic circuit is S _2,2 : OFF, S _2,1 : ON, S _1,2 : ON, S _1,1 : OFF, the potential of each terminal is 5: 2E, 4 ′: E 4: 0, 2 ': 0, 2: -E, 1: -2E. Then, by turning on the switching elements Su39, Su40, Su41, Su42, Su46, Su47, Sv45, Sv46, Sw47, Sw48 in the voltage selection circuit, OUT_U = 0, OUT_V = 2E, OUT_W = -2E at the output terminal. Can output.

  Further, by selectively turning on the switching elements of the voltage selection circuit, other combinations of the U, V, W phases and the output voltages of 2E, 0, -2E are possible.

That is, the potentials at both ends of the flying capacitors C _FC1 and C _FC2 can be independently connected to the output terminals OUT_U, OUT_V, and OUT_W by the bidirectional switch.

  Therefore, in the ninth embodiment, all combinations of 2E, E, 0, -E, and -2E can be output in three phases, and the U phase, V phase, and W phase, which were not possible in the fourth embodiment, are independent. This makes it possible to select a pattern.

In the ninth embodiment, the flying capacitors C _FC1 and C _FC2 are shared by three phases of U, V, and W phases, and a three-phase five-level power converter can be realized by two flying capacitors. Can be reduced in size.

[Embodiment 10]
Next, the multilevel power conversion device according to the tenth embodiment will be described with reference to FIG.

(1) Circuit Configuration The multilevel power conversion device according to the tenth embodiment is a basic circuit (N = 2) in which two basic cells are connected in series in the multilevel power conversion device according to the first embodiment. On the other hand, a three-phase (M = 3) phase module composed of a one-stage expansion circuit (K = 1) and a voltage selection circuit is connected.

  Here, the extension circuit according to the tenth embodiment will be described. Switching elements Su1, Su2, Su3, and Su4 are connected to terminals 4 ', 4, 2', and 2 of the basic circuit, respectively. A flying capacitor CU1 is inserted between the switching elements Su3 and Su4, and a flying capacitor CU2 is inserted between the switching elements Su1 and Su2.

  Further, both ends of the flying capacitor CU1 are terminals 2_2 and 2_2 ', and both ends of the flying capacitor CU2 are terminals 4_2 and 4_2'. The V phase and the W phase are configured similarly.

  Next, the voltage selection circuit will be described. In the U phase, switching elements Su5 and Su6 are connected in series between the terminal 4_2 'and the terminal 4_2, and switching elements Su7 and Su8 are inserted in series between the terminal 2_2' and the terminal 2_2 '. The switching elements Su9 and Su10 are connected in series between the common connection point of the switching elements Su5 and Su6 and the common connection point of the switching elements Su7 and Su8. The common connection point of the switching elements Su9 and Su10 is the U-phase. The output terminal OUT_U. The V phase and the W phase are configured similarly.

(2) Generation of Switching Pattern of Multilevel Power Conversion Device Here, the operation of the multilevel power conversion device according to the tenth embodiment will be described. DC capacitor C _DC1 , C _DC2 voltage 2E, basic circuit flying capacitors C _FC1 , C _FC2 voltage E, expansion circuit flying capacitors C _U1 , C _U2 , C _V1 , C _V2 , C _W1 , C _W2 Control to E / 2. Note that the reference point of the potential is the terminal 3.

Further, the states of the switching elements S _1.1 , S _1.2 , S _2.1 , S _2.2 , Su1, Su2, Su3, Su4 and the potentials of the terminals 2_2, 2_2 ′, 4_2, 4_2 ′ in the basic circuit and the U-phase extended circuit are shown. As shown in FIG. In Table 5, when S _1,1 : OFF, S _1,2 : ON, S _1,1 (/ S _1.2 ) = 0, S _1,1 : ON, S _1,2 : OFF In this case, S _1,1 (/ S _1.2 ) = 1. The same applies to S _2,1 (/ S _2,2 ), Su1 (/ Su2), and Su3 (/ Su4).

[Pattern 1] _{S 1,1: OFF, S 1,2:} ON, S 2,1: OFF, S 2,2: ON, Su1: OFF, Su2: ON, Su3: OFF, Su4: ON
The terminal 2_2 has a potential of -E, the terminal 2_2 'has a potential of -E / 2, the terminal 4_2 has a potential of E, and the terminal 4_2' has a potential of 3E / 2.

[Pattern 2] _{S 1,1: OFF, S 1,2:} ON, S 2,1: OFF, S 2,2: ON, Su1: OFF, Su2: ON, Su3: ON, Su4: OFF
The terminal 2_2 has a potential of -E / 2, the terminal 2_2 'has a potential of 0, the terminal 4_2 has a potential of E, and the terminal 4_2' has a potential of 3E / 2.

[Pattern 3] _{S 1,1: OFF, S 1,2:} ON, S 2,1: OFF, S 2,2: ON, Su1: ON, Su2: OFF, Su3: OFF, Su4: ON
The terminal 2_2 is -E, the terminal 2_2 'is -E / 2, the terminal 4_2 is 3E / 2, and the terminal 4_2' is 2E.

[Pattern 4] _{S 1,1: OFF, S 1,2:} ON, S 2,1: OFF, S 2,2: ON, Su1: ON, Su2: OFF, Su3: ON, Su4: OFF
The terminal 2_2 has a potential of -E / 2, the terminal 2_2 'has a potential of 0, the terminal 4_2 has a potential of 3E / 2, and the terminal 4_2' has a potential of 2E.

[Pattern 5] _{S 1,1: OFF, S 1,2:} ON, S 2,1: ON, S 2,2: OFF, Su1: OFF, Su2: ON, Su3: OFF, Su4: ON
The terminal 2_2 has a potential of -E, the terminal 2_2 'has a potential of -E / 2, the terminal 4_2 has a potential of 0, and the terminal 4_2' has a potential of E / 2.

[Pattern 6] _{S 1,1: OFF, S 1,2:} ON, S 2,1: ON, S 2,2: OFF, Su1: OFF, Su2: ON, Su3: ON, Su4: OFF
The terminal 2_2 has a potential of −E / 2, the terminal 2_2 ′ has a potential of 0, the terminal 4_2 has a potential of 0, and the terminal 4_2 ′ has a potential of E / 2.

[Pattern 7] _{S 1,1: OFF, S 1,2:} ON, S 2,1: ON, S 2,2: OFF, Su1: ON, Su2: OFF, Su3: OFF, Su4: ON
The terminal 2_2 is -E, the terminal 2_2 'is -E / 2, the terminal 4_2 is E / 2, and the terminal 4_2' is E potential.

[Pattern 8] _{S 1,1: OFF, S 1,2:} ON, S 2,1: ON, S 2,2: OFF, Su1: ON, Su2: OFF, Su3: ON, Su4: OFF
The terminal 2_2 is -E / 2, the terminal 2_2 'is 0, the terminal 4_2 is E / 2, and the terminal 4_2' is E.

[Pattern 9] _{S 1,1: ON, S 1,2:} OFF, S 2,1: OFF, S 2,2: ON, Su1: OFF, Su2: ON, Su3: OFF, Su4: ON
The terminal 2_2 has a potential of -2E, the terminal 2_2 'has a potential of -3E / 2, the terminal 4_2 has a potential of E, and the terminal 4_2' has a potential of 3E / 2.

[Pattern 10] _{S 1,1: ON, S 1,2:} OFF, S 2,1: OFF, S 2,2: ON, Su1: OFF, Su2: ON, Su3: ON, Su4: OFF
The terminal 2_2 has a potential of −3E / 2, the terminal 2_2 ′ has a potential of −E, the terminal 4_2 has a potential of E, and the terminal 4_2 ′ has a potential of 3E / 2.

[Pattern 11] _{S 1,1: ON, S 1,2:} OFF, S 2,1: OFF, S 2,2: ON, Su1: ON, Su2: OFF, Su3: OFF, Su4: ON
The terminal 2_2 has a potential of −2E, the terminal 2_2 ′ has a potential of −3E / 2, the terminal 4_2 has a potential of 3E / 2, and the terminal 4_2 ′ has a potential of 2E.

[Pattern 12] _{S 1,1: ON, S 1,2:} OFF, S 2,1: OFF, S 2,2: ON, Su1: ON, Su2: OFF, Su3: ON, Su4: OFF
The terminal 2_2 has a potential of −3E / 2, the terminal 2_2 ′ has a potential of −E, the terminal 4_2 has a potential of 3E / 2, and the terminal 4_2 ′ has a potential of 2E.

[Pattern 13] _{S 1,1: ON, S 1,2:} OFF, S 2,1: ON, S 2,2: OFF, Su1: OFF, Su2: ON, Su3: OFF, Su4: ON
The terminal 2_2 has a potential of −2E, the terminal 2_2 ′ has a potential of −3E / 2, the terminal 4_2 has a potential of 0, and the terminal 4_2 ′ has a potential of E / 2.

[Pattern 14] _{S 1,1: ON, S 1,2:} OFF, S 2,1: ON, S 2,2: OFF, Su1: OFF, Su2: ON, Su3: ON, Su4: OFF
The terminal 2_2 has a potential of −3E / 2, the terminal 2_2 ′ has a potential of −E, the terminal 4_2 has a potential of 0, and the terminal 4_2 ′ has a potential of E / 2.

[Pattern 15] _{S 1,1: ON, S 1,2:} OFF, S 2,1: ON, S 2,2: OFF, Su1: ON, Su2: OFF, Su3: OFF, Su4: ON
The terminal 2_2 has a potential of -2E, the terminal 2_2 'has a potential of -3E / 2, the terminal 4_2 has a potential of E / 2, and the terminal 4_2' has a potential of E.

[Pattern 16] _{S 1,1: ON, S 1,2:} OFF, S 2,1: ON, S 2,2: OFF, Su1: ON, Su2: OFF, Su3: ON, Su4: OFF
The terminal 2_2 has a potential of −3E / 2, the terminal 2_2 ′ has a potential of −E, the terminal 4_2 has a potential of E / 2, and the terminal 4_2 ′ has a potential of E.

  As described above, from pattern 1 to pattern 16, the terminal 2_2 has a potential of −2E, −3E / 2, −E, −E / 2, and the terminal 2_2 ′ has −3E / 2−. E, −E / 2, 0, any potential of 0, E / 2, E, 3E / 2 on the terminal 4_2, and E / 2, E, E on the terminal 4_2 ′. Since any potential of 3E / 2 and 2E can be output, by selecting one of the terminals 2_2, 2_2 ′, 4_2, and 4_2 ′ by the voltage selection circuit, −2E, −3E / 2, −E , −E / 2, 0, E / 2, E, 3E / 2, 2E can be output to the output terminals OUT_U, OUT_V, OUT_W.

  For example, by turning on Su5 and Su9 among the switching elements in the U-phase voltage selection circuit and turning off the other switching elements, the potential of the terminal 4_2 'can be output from the U-phase output terminal U_OUT. Further, by selecting the switching element of the voltage selection circuit and turning it ON, the voltages of the other terminals (4_2, 2_2'2_2) can be output from the output terminal.

As described above, according to the multi- (9) level power conversion circuit of the tenth embodiment, the flying capacitors C _FC1 and C _FC2 are shared by the three phases of U, V, and W phases, and the three-phase nine-level. This power conversion device can be realized with eight flying capacitors, so that the size of the device can be reduced.

  Although the present invention has been described in detail only for the specific examples described above, it is obvious to those skilled in the art that various changes and modifications are possible within the scope of the technical idea of the present invention. Such variations and modifications are naturally within the scope of the claims.

C _{DC1 to} C _DCN ... DC voltage source S _1.1 , S _1.2 , S _2.1 , S _2.2 , Su1 to Su48 ... Switching elements C _{FC1 to} C _FCN , C1 to CK ... Flying capacitor 1 ... Basic cell 2 ... Basic circuit 3 ... Expansion Circuit 5... Voltage selection circuit 41 to 4M... Phase module 1 to 2N + 1... Basic cell both ends (DC voltage source both ends) terminals 2, 2 'to 2N, 2N' ... Flying capacitor both ends terminals 2_1, 2_1 ' ˜2N_1, 2N_1 ′... Expansion circuit input terminals 2_2, 2_2 ′ to 2N_2, 2N_2 ′... Expansion circuit output terminals 2_3, 2_3 ′ to 2N_3, 2N_3 ′. OUT_W: Output terminal

Claims (8)

A multi-level power converter that generates an AC output converted from a voltage of a DC voltage source into a plurality of voltage levels,
A basic circuit having N (N ≧ 2) first basic cells in which switching elements, flying capacitors, and switching elements are sequentially connected in series between the positive and negative electrodes of N DC voltage sources connected in series; ,
A switching element, a flying capacitor, and a second basic cell in which the switching elements are sequentially connected in series are connected in parallel to the flying capacitor in each of the first basic cells, and a second capacitor is further connected to the flying capacitor of the second basic cell. An extension circuit in which basic cells are connected in parallel and this is repeated K times to connect K (K ≧ 1) second basic cells;
Both terminals of the flying capacitor of the Kth second basic cell of each expansion circuit are input terminals, and switching elements are respectively provided between the input terminals and the output terminals, and the switching elements are selectively turned on and off. A multi-level power conversion device comprising: an M-phase (M ≧ 3) voltage selection circuit that outputs the potential of any one of the input terminals from the output terminal. A multi-level power converter that generates an AC output converted from a voltage of a DC voltage source into a plurality of voltage levels,
A basic circuit having N (N ≧ 2) first basic cells in which switching elements, flying capacitors, and switching elements are sequentially connected in series between the positive and negative electrodes of N DC voltage sources connected in series; ,
Both end terminals of the flying capacitors of the first basic cells are input terminals, switching elements are provided between the input terminals and the output terminals, and the switching elements are selectively turned on and off to thereby input the input terminals. A multi-level power conversion device comprising: an M-phase (M ≧ 3) voltage selection circuit that selects a potential of any one of the terminals and outputs the selected potential from the output terminal. A multi-level power converter that generates an AC output converted from a voltage of a DC voltage source into a plurality of voltage levels,
A basic circuit having N (N ≧ 2) first basic cells in which switching elements, flying capacitors, and switching elements are sequentially connected in series between the positive and negative electrodes of N DC voltage sources connected in series; ,
The both ends of the flying capacitor of each first basic cell and all or any of the terminals of each DC voltage source are input terminals, each having a switching element between each input terminal and the output terminal, An M-phase (M ≧ 3) voltage selection circuit that outputs the potential of any one of the input terminals from the output terminal by selectively ON / OFF controlling the switching element; A multi-level power conversion device. The basic circuit is:
The multilevel power conversion device according to claim 2, further comprising a switching element between one of both terminals of the flying capacitor of each first basic cell and an input terminal of the voltage selection circuit. The voltage selection circuit includes:
The common connection point between the both terminals of the flying capacitor of each first basic cell and each DC voltage source is used as an input terminal.
4. The multilevel power conversion device according to claim 3, wherein the switching element between each common connection point and the output terminal of the voltage selection circuit is a bidirectional switch that can be controlled in a reverse withstand voltage direction. The voltage selection circuit includes:
Both end terminals of the flying capacitor of each first basic cell and both end terminals of a series circuit in which each DC voltage source is connected in series are input terminals, and the input terminals are connected to both end terminals of the flying capacitor of the first basic cell. 4. The multilevel power conversion device according to claim 3, wherein the switching element is a bidirectional switch that can be controlled in the reverse withstand voltage direction.   The multilevel power conversion according to any one of claims 1 to 6, wherein a part or all of the switching elements in the basic circuit, the voltage selection circuit, or the extension circuit have a series number of 2 or more. apparatus.   The multilevel power conversion according to any one of claims 1 to 7, wherein a part or all of the switching elements in the basic circuit, the voltage selection circuit, or the extension circuit have a parallel number of 2 or more. apparatus.

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