JP2021016242A - Power conversion device - Google Patents

Abstract

To provide a power conversion device in which the energy loss can be minimized and upsizing of which can be avoided.SOLUTION: A power conversion device according to an embodiment includes a second circuit 400 that is connected between a positive-side DC end and a negative-side DC end, and a first circuit 300 that is connected between the second circuit 400 and an AC end. The first circuit 300 includes: an inverter cell 100; an upper arm that is formed by connecting in series one or more first switch circuits 101N each including a first switching element 1UN, a first diode 4UN, and a first capacitor 3UN; a lower arm that is formed by connecting in series one or more second switch circuits 102M each including a second switching element 1XM, a second diode 4XM, and a second capacitor 3XM; and a circuit that connects a low-potential side end of the inverter cell 100 to a low-potential side end of the first capacitor 3UN, and connects a high-potential side end of the inverter cell 100 to a high-potential side end of the second capacitor 3XM.SELECTED DRAWING: Figure 1

Description

Embodiments of the present invention relate to a power converter.

For example, according to a power converter equipped with a snubber circuit that suppresses the parasitic inductance existing in the switching loop and the surge voltage generated by switching, the energy of the surge voltage absorbed by the snubber circuit is regenerated into the DC power supply. , It is possible to improve energy efficiency.

Further, in recent years, a multi-level power converter capable of outputting a plurality of levels of voltage has been proposed. In a multi-level power converter, it is possible to suppress switching loss without increasing the switching speed by increasing the output voltage to multiple levels.

Japanese Unexamined Patent Publication No. 7-21307

However, the power conversion device provided with the snubber circuit described above causes the snubber circuit to absorb the energy of the surge voltage generated by increasing the switching speed, and causes a loss due to switching when the switching speed is low. It was difficult to suppress.

Further, in the diode clamp type multi-level converter and the flying capacitor type multi-level converter, the switching loss can be reduced without increasing the switching speed by lowering the applied voltage per switching element. .. However, diode clamp type and flying capacitor type multi-level power converters may have a larger parasitic inductance in the switching loop than conventional two-level power converters, resulting in larger surge voltages. In this case, the switching speed had to be further lowered to suppress the surge voltage, and the effect of reducing the switching loss could not be fully utilized.

Further, the modular multi-level converter has a configuration in which the switching loop is closed in one module composed of DC capacitors connected in parallel to two series switching devices. Since the parasitic inductance does not increase due to this configuration, it is not necessary to reduce the switching speed in order to suppress the surge voltage. On the other hand, since the current of the primary component (fundamental wave component) or the secondary component of the AC frequency flows through the DC capacitor, it is necessary to increase the size of the DC capacitor, and it is difficult to miniaturize the power conversion device. It was.

An embodiment of the present invention has been made in view of the above circumstances, and an object of the present invention is to provide a power conversion device capable of suppressing energy loss to a low level and avoiding an increase in size.

The power conversion device according to the embodiment includes an upper high withstand voltage inverter cell electrically connected to the positive DC end at the high potential side end and electrically connected to the intermediate end at the low potential side end, and a high potential side. A lower high withstand voltage inverter cell that is electrically connected to the intermediate end at the end and electrically connected to the negative DC end at the low potential side end, and is connected between the AC end and the high potential side end. The upper switching element, the lower switching element connected between the AC end and the low potential side end, and the upper switching element and the lower switching element between the high potential side end and the low potential side end. A first inverter cell having a floating capacitor connected in parallel to the other, connected between the high potential side end of the inverter cell and the output end of the upper high withstand voltage inverter cell, and having a first switching element. The upper arm configured by connecting one or more switch circuits in series is connected between the low potential side end of the inverter cell and the output end of the lower high withstand voltage inverter cell, and has a second switching element. A lower arm configured by connecting one or more second switch circuits in series is provided, and the upper high withstand voltage inverter cell and the lower high withstand voltage inverter cell are located between a high potential side end and an output end. An upper high withstand voltage switching element connected, a lower high withstand voltage switching element connected between the low potential side end and the output end, and a DC inverter connected between the high potential side end and the low potential side end. The first diode having a cathode connected to the low potential side end of the first switching element, the inverter of the first diode, and the height of the first switching element, at least one of the first switch circuits. When it has a first capacitor connected between the potential side end, it has a first regenerative rectification circuit that connects the low potential side end of the inverter cell and the low potential side end of the first capacitor. At least one of the second switch circuits includes a second diode in which an inverter is connected to the high potential side end of the second switching element, a cathode of the second diode, and a low potential side end of the second switching element. When it has a second capacitor connected between the two, it has a second regenerative rectifier circuit that connects the high potential side end of the inverter cell and the high potential side end of the second capacitor.

FIG. 1 is a diagram schematically showing an example of the configuration of the power conversion device of one embodiment. FIG. 2 is a diagram for explaining an example of the operation of the power conversion device of the first embodiment. FIG. 3 is a diagram for explaining an example of the operation of the first circuit of the power conversion device of one embodiment. FIG. 4 is a diagram for explaining another example of the operation of the first circuit of the power conversion device of one embodiment. FIG. 5A is a diagram showing an example of loss caused by turning on the switching element in a conventional two-level inverter as a comparative example. FIG. 5B is a diagram showing an example of a loss caused in the arm when the switching element is turned on in the power conversion device of one embodiment. FIG. 5C is a diagram showing an example of a loss generated for each element when the switching element is turned on in the power conversion device of one embodiment. FIG. 6A is a diagram showing an example of the loss caused by the turn-off of the switching element in the conventional two-level inverter as a comparative example. FIG. 6B is a diagram showing an example of a loss caused in the arm due to the switching element turning off in the power conversion device of one embodiment. FIG. 6C is a diagram showing an example of a loss generated for each element when the switching element is turned off in the power conversion device of one embodiment. FIG. 7A is a diagram showing an example of recovery loss generated in a conventional two-level inverter as a comparative example. FIG. 7B is a diagram showing an example of recovery loss generated in the power conversion device of one embodiment. FIG. 8 is a diagram schematically showing an example of the configuration of the power conversion device of one embodiment. FIG. 9 is a diagram for explaining an example of the operation of the power conversion device of the second embodiment. FIG. 10 is a diagram schematically showing an example of the configuration of the power conversion device of one embodiment. FIG. 11 is a diagram schematically showing an example of the configuration of the power conversion device of one embodiment. FIG. 12 is a diagram schematically showing an example of the configuration of the power conversion device of one embodiment. FIG. 13 is a diagram schematically showing an example of the configuration of the power conversion device of one embodiment. FIG. 14 is a diagram schematically showing an example of the configuration of the power conversion device of one embodiment. FIG. 15 is a diagram schematically showing an example of the configuration of the power conversion device of one embodiment. FIG. 16 is a diagram schematically showing an example of the configuration of the power conversion device of one embodiment.

Hereinafter, the power conversion device of the embodiment will be described in detail with reference to the drawings.
FIG. 1 is a diagram schematically showing an example of the configuration of the power conversion device of one embodiment.
The power conversion device of the present embodiment includes a first circuit 300, a second circuit 400, a positive DC end 209, a negative DC end 210, and an AC end 212.

The first circuit 300 includes an inverter cell 100, an upper arm, a lower arm, n (n is an integer of 2 or more) first regenerative rectifier circuits (regenerative rectifier diode 6 UN and a first resistor 5 UN), and m. It includes two (m is an integer of 2 or more) second regenerative rectifier circuits (regenerative rectifier diode 6XM and second resistor 5XM). Here, N and M are N = 2 to n and M = 2 to m, respectively, and the same applies thereafter unless other definitions are shown.

The upper arm of the power conversion device of this embodiment includes n switch circuits (voltage type clamp type switch circuits) 101N. The lower arm of the power conversion device of this embodiment includes m switch circuits (voltage type clamp type switch circuits) 102M.

In the power conversion device of the present embodiment, between the positive DC end 209 and the negative DC end 210 (or between the positive DC end 209 and the intermediate end 211 and between the intermediate end 211 and the negative DC end 210). A DC capacitor (not shown) is electrically connected to (between 210). The DC capacitor may be included in the power converter or may be mounted outside the power converter.

The inverter cell 100 includes a switching element (upper switching element) 1U, a switching element (lower switching element) 1X, a floating capacitor 2, a positive cell terminal (high potential side end) 200, and a negative cell terminal (low). It includes a potential side end) 201 and a cell AC terminal (AC end) 202. The positive cell terminal 200, the negative cell terminal 201, and the cell AC terminal 202 may be configured so that the circuits can be electrically connected at the positions of these terminals, and the terminals may be omitted. I do not care.

The switching element 1U and the switching element 1X are, for example, MOSFETs (metal-oxide semiconductor field-effect transistors). The drain (high potential side end) of the switching element 1U is electrically connected to the positive cell terminal 200, and the source (low potential side end) is electrically connected to the drain (high potential side end) of the switching element 1X. There is. The source (low potential side end) of the switching element 1X is electrically connected to the negative side cell terminal 201. The switching element 1U and the switching element 1X are electrically connected to the cell AC terminal 202.

The floating capacitor 2 is connected in parallel with the switching element 1U and the switching element 1X. One end of the floating capacitor 2 is electrically connected to the drain of the switching element 1U and the positive cell terminal 200, and the other end of the floating capacitor 2 is electrically connected to the source of the switching element 1X and the negative cell terminal 201. There is.

Each of the n switch circuits (first switch circuit) 101N includes a switching element (first switching element) 1UN, a diode (first diode) 4UN, a capacitor (first capacitor) 3UN, a snubber terminal 205N, and the like. It includes a positive terminal 203N and a negative terminal 204N.

The snubber terminal 205N, the positive terminal 203N, and the negative terminal 204N may be configured so that the circuit can be electrically connected at the positions of these terminals, and the terminals may be omitted. Further, the switch circuit 101N may include a plurality of switching elements 1UN. In that case, the plurality of switching elements 1UN are connected in parallel to the capacitor 3UN and the diode 4UN between the positive terminal 203N and the negative terminal 204N. A plurality of switching elements 1UN may be connected in series with each other or may be connected in parallel with each other.

The switching element 1UN is, for example, a MOSFET. The drain (high potential side end) of the switching element 1UN is electrically connected to the positive terminal 203N, and the source (low potential side end) of the switching element 1UN is electrically connected to the negative terminal 204N.

In the diode 4UN, the cathode is electrically connected to the source and the negative terminal 204N of the switching element 1UN, and the anode is electrically connected to the snubber terminal 205N. It is desirable that the diode 4UN has fast recovery characteristics with low recovery loss. For example, an element using a Schottky barrier diode (SBD) or a wide bandgap semiconductor (SiC, GaN, etc.) having good recovery characteristics is used. Is desirable.

One end (high potential side end) of the capacitor 3UN is electrically connected to the drain of the switching element 1UN and the positive terminal 203N, and the other end (low potential side end) is electrically connected to the anode of the diode 4UN and a snubber. It is electrically connected to the terminal 205N.

The n switch circuits 101N are connected in series. That is, the positive terminal (high potential side end) 203N of the switch circuit 101N is electrically connected to the negative terminal (low potential side end) 204N of the adjacent switch circuit 101N on the high potential side, and is on the highest potential side. The positive terminal 203N (N = n) of the switch circuit 101N is electrically connected to the second circuit 400. The negative terminal 204N of the switch circuit 101N is electrically connected to the positive terminal 203N of the adjacent switch circuit 101N on the low potential side, and the negative terminal 204N (N = 1) of the switch circuit 101N on the lowest potential side is , Is electrically connected to the positive cell terminal 200 of the inverter cell 100.

The n regenerative rectifying diodes 6UN (N = 1 to n) are terminals on the low potential side of the switching element 1X (the low potential side end of the inverter cell 100) with the direction from the low potential side to the high potential side as the forward direction. Is connected to the low potential side end of the capacitor 3U1 of the first switch circuit 1011 arranged on the lowest potential side, and between the low potential side end of the capacitor 3UN of the adjacent first switch circuit 101N. They are connected in series with each other.

Regenerative rectifier diode (1st regenerative rectifier diode) 6UN (N = 1 to n) Each cathode is a snubber terminal 205N (N = 1 to n) of the switch circuit 101N and a regenerative rectifier diode 6UN (N = 1 to n) adjacent to each other on the high potential side. It is electrically connected to the anode of N = 1 to n). For example, the cathode of the regenerative rectifying diode 6Uk (1 ≦ k ≦ n-1) is electrically connected to the snubber terminal 205k of the switch circuit 101k and the anode of the regenerative rectifying diode 6U (k + 1).

At one end, the resistor 5UN is connected in series to a parallel circuit of the diode 4UN and the capacitor 3UN. The other end of the resistor 5UN is electrically connected to a circuit in which the capacitor 3UN of the switch circuit 101N connected to the low potential side and the resistor 5UN are connected in series via a regenerative rectifier diode 6UN. The other end of the resistor 5UN of the switch circuit 101N (N = 1) arranged on the lowest potential side is electrically connected to the negative cell terminal 201 of the inverter cell 100 via the snubber terminal 205N and the regenerative rectifier diode 6UN. It is connected.

Each of the m switch circuits (second switch circuit) 102M includes a switching element (second switching element) 1XM, a diode (second diode) 4XM, a capacitor (second capacitor) 3XM, and a snubber terminal 208M. It includes a positive terminal 206M and a negative terminal 207M.

The positive terminal 206M, the negative terminal 207M, and the snubber terminal 208M may be configured so that the circuit can be electrically connected at the positions of these terminals, and the terminals may be omitted. Further, the switch circuit 102M may include a plurality of switching elements 1XM. In that case, the plurality of switching elements 1XM are connected in parallel to the capacitor 3XM and the diode 4XM between the positive terminal 206M and the negative terminal 207M. The plurality of switching elements 1XM may be connected in series with each other or may be connected in parallel with each other.

The switching element 1XM is, for example, a MOSFET. The drain (high potential side end) of the switching element 1XM is electrically connected to the positive terminal 206M, and the source (low potential side end) is electrically connected to the negative terminal 207M.

In the diode 4XM, the anode is electrically connected to the drain and the positive terminal 206M of the switching element 1XM, and the cathode is electrically connected to the snubber terminal 208M. It is desirable that the diode 4XM has fast recovery characteristics with low recovery loss. For example, an element using a Schottky barrier diode (SBD) or a wide bandgap semiconductor (SiC, GaN, etc.) having good recovery characteristics is used. Is desirable.

One end (low potential side end) of the capacitor 3XM is electrically connected to the source and negative terminal 207M of the switching element 1XM, and the other end (high potential side end) is electrically connected to the cathode of the diode 4XM. It is electrically connected to the snubber terminal 208M.

The m switch circuits 102M are connected in series. That is, the positive terminal 206M of the switch circuit 102M is electrically connected to the negative terminal 207M of the adjacent switch circuit 102M on the high potential side, and the positive terminal 206M (M = 1) of the switch circuit 102M on the highest potential side is electrically connected. ) Is electrically connected to the negative cell terminal 201 of the inverter cell 100. The negative terminal 207M of the switch circuit 102M is electrically connected to the positive terminal 206M of the adjacent switch circuit 102M on the low potential side, and the negative terminal 207M (M = m) of the switch circuit 102M on the lowest potential side is , Electrically connects to the second circuit 400.

The m regenerative rectifying diodes (second regenerative rectifying diodes) 6XM (M = 1 to m) have the height of the capacitor 3XM of the adjacent second switch circuit 102M with the direction from the low potential side to the high potential side as the forward direction. Between the potential side ends and between the high potential side terminal of the switching element 1U (the high potential side end of the inverter cell 100) and the high potential side end of the capacitor 3X1 of the second switch circuit 1021 arranged on the highest potential side. They are connected to each other and connected in series with each other.

Regenerative rectifier diode 6XM (M = 1 to m) Each anode is a snubber terminal 208M (M = 1 to m) of the switch circuit 102M and a regenerative rectifier diode 6XM (M = 1 to m) adjacent to the low potential side. It is electrically connected to the cathode. For example, the anode of the regenerative rectifying diode 6Xj (1 ≦ j ≦ m-1) is electrically connected to the snubber terminal 208j of the switch circuit 102j and the cathode of the regenerative rectifying diode 6X (j + 1).

At one end, the resistor 5XM is connected in series with a parallel circuit of the diode 4XM and the capacitor 3XM. The other end of the resistor 5XM is electrically connected to a circuit in which the capacitor 3XM of the switch circuit 102M connected to the high potential side and the resistor 5XM are connected in series via a regenerative rectifier diode 6XM. The other end of the resistor 5XM of the switch circuit 102M (M = 1) arranged on the highest potential side is electrically connected to the positive cell terminal 200 of the inverter cell 100 via the snubber terminal 208M and the regenerative rectifier diode 6XM. It is connected.

That is, in the power conversion device of the present embodiment, at least one of the first switch circuits 101N has a first diode 4UN whose cathode is connected to the low potential side end of the first switching element 1UN, and an anode and a first of the first diode 4UN. When the first capacitor 3UN connected between the 1 switching element 1UN and the high potential side end is provided, the low potential side end of the inverter cell 100 and the low potential side end in the direction from the low potential side to the high potential side are forward directions. It is provided with a regenerative rectifying circuit that connects to the low potential side end of the first capacitor 3UN of the upper arm.

Further, in the power conversion device of the present embodiment, at least one of the second switch circuits 102X has a second diode 4XM in which an anode is connected to the high potential side end of the second switching element 1XM, and a cathode and a second of the second diode 4XM. When the second capacitor 3XM connected between the two switching elements 1XM and the low potential side end is provided, the direction from the low potential side to the high potential side is the forward direction, and the high potential side end of the inverter cell 100 and the high potential side end. It is provided with a regenerative rectifying circuit that connects the high potential side end of the second capacitor 3XM of the lower arm.

In the power conversion device of the present embodiment, it is desirable that the number n of the switch circuit 101N and the number m of the switch circuit 102M are the same, but n and m may be different numbers.

Further, in the power conversion device of the present embodiment, the switching elements 1U, 1X, 1UN, and 1XM are not limited to MOSFETs, and may be IGBTs (Insulated Gate Bipolar transistors), mechanical switches, or the like.

Further, even when elements having different voltage ratings and current ratings are used as the switching elements 1U, 1X, 1UN, and 1XM, the effect of this embodiment can be obtained, but the elements having the same voltage rating and current rating. Is preferably used as the switching elements 1U, 1X, 1UN, and 1XM.
Further, the first resistor 5UN and the second resistor 5XM provided in the first circuit 300 may be replaced with a reactor or an inductance element.

The second circuit 400 includes an upper high withstand voltage inverter cell 106p and a lower high withstand voltage inverter cell 106n.
The upper high withstand voltage inverter cell 106p and the lower high withstand voltage inverter cell 106n are connected in series between the positive DC end 209 and the negative DC end 210. The upper high withstand voltage inverter cell 106p and the lower high withstand voltage inverter cell 106n are electrically connected to the intermediate terminal 211 of the entire circuit of the power conversion device of the present embodiment.

The upper high withstand voltage inverter cell 106p includes high withstand voltage switching elements 8pu and 8px, and a DC capacitor 9p. The high withstand voltage switching element 8pu and the high withstand voltage switching element 8px are, for example, high withstand voltage MOSFETs.
The high withstand voltage switching elements (upper high withstand voltage switching elements) 8pu and 8nu are connected between the high potential side end and the output end of the high withstand voltage inverter cells 106p and 106n. The high withstand voltage switching elements (lower high withstand voltage switching elements) 8px and 8nx are connected between the low potential side end and the output end of the high withstand voltage inverter cells 106p and 106n.

The high withstand voltage switching element 8pu is electrically connected to the positive DC end 209 at the drain and electrically connected to the drain of the high withstand voltage switching element 8px at the source. The high withstand voltage switching element 8px is electrically connected to the lower high withstand voltage inverter cell 106n at the source.
The DC capacitor 9p is connected between the drain of the high withstand voltage switching element 8pu and the source of the high withstand voltage switching element 8px.

The upper high withstand voltage inverter cell 106p is electrically connected to the positive terminal 203n of the nth switch circuit (first switch circuit) 101n between the high withstand voltage switching element 8pu and the high withstand voltage switching element 8px.

The lower high withstand voltage inverter cell 106n includes high withstand voltage switching elements 8nu and 8nx, and a DC capacitor 9n. The high withstand voltage switching element 8pu and the high withstand voltage switching element 8px are, for example, high withstand voltage MOSFETs.

The high withstand voltage switching element 8nu (upper withstand voltage switching element) is electrically connected to the upper withstand voltage inverter cell 106p at the drain and electrically connected with the drain of the high withstand voltage switching element 8nx at the source. The high withstand voltage switching element (lower high withstand voltage switching element) 8nx is electrically connected to the negative DC end 210 at the source.
The DC capacitor 9n is connected between the drain of the high withstand voltage switching element 8nu and the source of the high withstand voltage switching element 8nx.

The lower high withstand voltage inverter cell 106n is electrically connected to the negative terminal 207m of the mth switch circuit (second switch circuit) 102m between the high withstand voltage switching element 8nu and the high withstand voltage switching element 8nx. ..
In the power conversion device of the present embodiment, the high withstand voltage switching elements 8pu, 8px, 8nu, and 8nx are not limited to MOSFETs, and may be IGBTs (Insulated Gate Bipolar Transistors), mechanical switches, or the like.

In the power conversion device of this embodiment, the positive DC end 209, the negative DC end 210, the positive DC end 209 and the intermediate terminal 211, and the negative DC end 210 and the intermediate terminal 211 are connected. A closed circuit is constructed via a DC capacitor (not shown). A surge voltage may be generated due to the parasitic inductance (not shown) parasitic on this closed circuit. At this time, in the power conversion device of the present embodiment, it is possible to suppress the surge voltage generated by the capacitors 3UN and 3XM.

Next, an example of the operation of the power conversion device of this embodiment will be described.
FIG. 2 is a diagram for explaining an example of the operation of the power conversion device of the first embodiment.
Here, the waveforms of the gate signals of the high withstand voltage switching elements 8pu, 8px, 8nu, and 8nx of the second circuit 400, the output voltage waveform of the first circuit 300, the output voltage waveform of the second circuit 400, and the power converter ( An example is shown with the output voltage waveform of the inverter).

In the example shown in FIG. 2, the upper high withstand voltage inverter cell 106p and the lower high withstand voltage inverter cell 106n perform the same operation. That is, the gate signal Spu of the upper high withstand voltage switching element 8pu of the upper high withstand voltage inverter cell 106p and the gate signal Snu of the upper high withstand voltage switching element 8nu of the lower high withstand voltage inverter cell 106n have the same waveform. The gate signal Spx of the lower high withstand voltage switching element 8px of the upper high withstand voltage inverter cell 106p and the gate signal Snx of the lower high withstand voltage switching element 8nx of the lower high withstand voltage inverter cell 106n have the same waveform.

In the power conversion device of the present embodiment, the upper high withstand voltage inverter cell 106p and the lower high withstand voltage inverter cell 106n of the second circuit 400 are turned on by turning on the upper high withstand voltage switching elements 8pu and 8nu, respectively. The polarity of the output voltage of the power converter becomes positive, and the polarity of the output voltage of the power converter becomes negative by turning on the lower high withstand voltage switching elements 8px and 8nx.

The first circuit 300 can create an arbitrary waveform by performing PWM modulation (Pulse Width Modulation). In the example shown in FIG. 2, for example, by comparing the voltage command value that outputs the difference between the sine wave and the output voltage of the second circuit 400 and the triangular wave, the gate signal of the upper arm and the lower arm of the first circuit 300 are compared. Is generating the gate signal of.

In the power conversion device of the present embodiment, an arbitrary waveform (for example, a sine wave) can be output by operating the second circuit 400 and the first circuit 300 as described above.

Next, an example of the operation of the first circuit 300 in the power conversion device of the present embodiment will be described.
In the power conversion device of the present embodiment, the plurality of switching elements 1UN of the upper arm of the first circuit 300 and the plurality of switching elements 1XM of the lower arm are sequentially switched at predetermined time intervals, respectively. It is possible to reduce losses such as turn-on loss, turn-off loss, and recovery loss.

Current is output from the AC end 212 in a state where the switching elements 1U and 1X of the inverter cell 100, the plurality of switching elements 1UN of the upper arm, and the plurality of switching elements 1XM of the lower arm are all off. Occasionally, the current flows through the parasitic diode of the switching element 1X of the inverter cell 100 and the parasitic diode of the switching element 1XM of the switch circuit 102M.

In this state, when the switching element 1U of the inverter cell 100 is turned on, the current flows through the parasitic diodes of the plurality of switching elements 1XM of the switch circuit 102M of the lower arm, and the floating capacitor 2 is discharged in the inverter cell 100. , Passes through the switching element 1U, and flows to the AC end 212.

Subsequently, any one of the switching elements 1UN of the switch circuit 101N of the upper arm is turned on. Here, the case where the switching element 1Un of the switch circuit 101n is turned on will be described.

When the switching element 1Un is turned on, the voltage applied to one of the plurality of switch circuits 101N is divided by the number of series (= m) of the plurality of switch circuits 102M and applied to each of the plurality of switch circuits 102M. Will be done. Therefore, the voltage applied at the time of recovery of the parasitic diode of the switching element 1XM of the plurality of switch circuits 102M becomes small, and the loss (recovery loss) generated at the time of recovery is reduced. Further, the parasitic inductance of the switching loop, which increases according to the number of series of the plurality of switch circuits 102M, reduces the amount of change in the recovery current, and as a result, the recovery charge is reduced and the recovery loss is reduced.

When a voltage is applied to the switch circuit 102M, the current cannot pass through the parasitic diode of the switching element 1XM and is commutated to the switch circuit 101N. Therefore, in the switch circuit 101n, a current flows through the switching element 1Un that is turned on, and in the switch circuit 1011 to 101 (n-1), the capacitors 3U1 to 3U (n-1) and the diodes 4U1 to 4U (n-1) ) And current flows through.

By transitioning the state in which the current flows, for example, in the conventional two-level inverter, the energy converted into heat as a switching loss is converted into capacitors 3U1 to 3U (n-1) in the power conversion device of the present embodiment. It will be stored. That is, the switching loss in the power conversion device of the present embodiment is only the loss associated with the switching of the switching element 1UN of the plurality of switch circuits 101N, which is sufficiently smaller than that of the conventional two-level inverter.
Further, for example, when the switching element 1Un is turned on, the diode 4Un and the capacitor 3Un of the switch circuit 101n are connected in parallel.

One end of the resistor 5Un is connected in series with a parallel circuit of the diode 4Un and the capacitor 3Un. The other end of the resistor 5Un is via a circuit in which the capacitor 3U (n-1) of the switch circuit 101 (n-1) and the resistor 5U (n-1) are connected in series, and a regenerative rectifier diode 6Un. It is electrically connected. As a result, the energy stored in the capacitor 3Un is discharged to the capacitor 3U (n-1). The discharge ends when the voltages of the capacitor 3Un and the capacitor 3U (n-1) become equal.

In the above example, when the voltage of the capacitor 3Un is higher than the voltage of the capacitor 3U (n-1), the capacitor 3Un is discharged. Further, since the difference between the voltage of the capacitor 3Un and the voltage of the capacitor 3U (n-1) is sufficiently smaller than the voltage of each of the capacitors 3Un and 3U (n-1), the resistor 5Un is used in the path of the discharged energy. Even if 5U (n-1) is present, it can be discharged with high efficiency.

When the switching elements 1UN of the plurality of switch circuits 101N are sequentially turned on and all the switching elements 1UN are turned on, the energy stored in the capacitor 3UN is sequentially discharged, and the discharged energy is stored in the floating capacitor 2. .. In this state, the switching element of the upper arm of the power converter is turned on.

After that, when the plurality of switching elements 1UN are sequentially turned off and all of the plurality of switching elements 1UN are turned off, the floating capacitor 2 is discharged, and the energy generated by the switching can be efficiently regenerated. After that, the switching element 1U is turned off, and the upper arm of the power converter is turned off.

Further, by operating the switching element 1X and the plurality of switch circuits 102M in the same manner, it is possible to store the energy generated by the switching in the floating capacitor 2 via the plurality of capacitors 3XM, and discharge the floating capacitor 2. By doing so, it is possible to efficiently regenerate the energy generated by switching.

As described above, in the power conversion device of the present embodiment, for example, most of the energy at the time of switching, which was a loss in the conventional two-level inverter, can be stored in the floating capacitor 2 via the capacitors 3UN and 3XM. Therefore, by discharging the floating capacitor 2, it is possible to reduce the switching loss without increasing the switching speed. Further, the recovery loss can be reduced by applying a low voltage to the switching elements 1UN and 1XM at the time of recovering the parasitic diode of the switching elements 1UN and 1XM.

FIG. 3 is a diagram for explaining an example of the operation of the first circuit of the power conversion device of one embodiment.
Here, a timing chart showing an example of turn-on timing and turn-off timing between the gate signal Su of the switching element 1U and the gate signal Su (N) of the plurality of switching elements 1UN of the upper arm, and the current flowing through the plurality of capacitors 3UN are shown. An example of the relationship between the icu (N) and the current icf flowing through the floating capacitor 2 is shown. In FIG. 3, the current icu (N) and the current icf are positive in the direction of output from the AC end 212. Further, during the period shown in FIG. 3, the switching element 1X and the plurality of switching elements 1XM of the lower arm are in a state of being turned off.

First, the switching element 1U of the inverter cell 100 is turned on from the state where the switching element 1U and the plurality of switching elements 1UN of the upper arm are turned off. As a result, the current icf flows through the floating capacitor 2, and the stored energy is discharged.

Subsequently, the switching elements 1UN of the plurality of switch circuits 101N of the upper arm are sequentially turned on. The order in which the switching elements 1UN of the plurality of switch circuits 101N are turned on is not limited. Here, an example will be described in which the switching element 1Un of the switch circuit 101n is sequentially turned on to the switching element 1U1 of the switch circuit 1011 on the side closer to the inverter cell 100.

When the switching element 1Un is turned on, the current flowing from the negative terminal of the first circuit 300 (negative terminal 207m of the switch circuit 102m) to the parasitic diode of the switching element 1XM of the plurality of switch circuits 102M of the lower arm is transferred. , The current is commutated so as to flow to the positive terminal of the first circuit 300 (the positive terminal 203n of the switch circuit 101n). As a result, the discharge of the floating capacitor 2 is completed.

When the current is commutated to the positive terminal 203n, the switching element 1Un turned on, the capacitors 3U1 to 3U (n-1) and the diode connected in parallel to the switching elements 1U1 to 1U (n-1) turned off are connected in parallel. A current flows through 4U1 to 4U (n-1).

Further, a capacitor 3Un connected in parallel with the turned-on switching element 1Un and a capacitor 3U (n-1) of the switch circuit 101 (n-1) connected to the low potential side are connected via a regenerative rectifying diode 6Un. The energy connected and stored in the capacitor 3Un is discharged to the capacitor 3U (n-1).

Next, when the switching element 1U (n-1) of the switch circuit 101 (n-1) connected to the low potential side of the switch circuit 101n is turned on, the current flowing through the capacitor 3U (n-1) Is commutated to the switching element 1U (n-1), and charging of the capacitor 3U (n-1) is completed.

Subsequently, when the switching element 1U (n-1) of the switch circuit 101 (n-1) is turned on, the capacitor 3U (n-1) and the switch circuit 101 (n-2) connected to the low potential side are connected. The capacitor 3U (n-2) is connected via the regenerative rectifier diode 6U (n-1), and the energy stored in the capacitor 3U (n-1) is discharged to the capacitor 3U (n-2). ..

In the example shown in FIG. 3, the timing of two discharge operations, that is, the discharge from the capacitor 3Un to the capacitor 3U (n-1) and the discharge from the capacitor 3U (n-1) to the capacitor 3U (n-2). However, the discharge between the capacitors 3UN changes according to the voltage relationship of the capacitors 3UN, and is not limited to this example. For example, when the voltage of the capacitor 3Un is higher than that of the capacitor 3U (n-1) and the capacitor 3U (n-2), the energy stored in the capacitor 3Un is the capacitor 3U (n-1) and the capacitor 3U (n-2). ) Is discharged. That is, the energy stored in the capacitor 3Un can be discharged to one or more other capacitors 3UN with a lower voltage.

For example, as shown in FIG. 3, when the switching element 1U is turned on and the switching element 1Un to the switching element 1U1 is sequentially turned on, all the switching elements of the upper arm of the power converter are turned on, and the capacitor 3Un to the capacitor 3U1 are turned on. The sequentially discharged energy is finally charged to the floating capacitor 2.

Subsequently, the switching element 1U of the inverter cell 100 and the switching element 1UN of the plurality of switch circuits 101N are sequentially turned off. The order in which the switching element 1UN is turned off is not limited. Here, an example will be described in which the switching element 1U1 of the switch circuit 1011 on the side closer to the inverter cell 100 (the side having the lower potential) is sequentially turned off to the switching element 1Un of the switch circuit 101n. The switching element 1U is turned off after all of the plurality of switching elements 1UN are turned off.

When the switching element 1U and the switching element 1UN are all turned on, for example, when the switching element 1U1 is turned off, the current flowing through the switching element 1U1 flows to the capacitor 3U1 and the capacitor 3U1 is charged. At this time, for example, in a conventional two-level inverter, energy that becomes heat as a switching loss is charged to the capacitor 3U1, so that highly efficient switching operation can be performed.

The above turn-off operation is sequentially performed from the switching element 1U1 to the switching element 1Un. As a result, the energy charged in the capacitors 3U1 to 3U (n-1) is sequentially discharged to the capacitors 3Un. Subsequently, when the switching element 1Un is turned off, the energy stored in the capacitor 3Un is finally charged in the floating capacitor 2.

When the turn-off operation is completed, the switching element 1U is turned on, the plurality of switching elements 1UN are all turned off, and the energy charged in the floating capacitor 2 is discharged. As a result, the energy stored in the floating capacitor 2 can be efficiently regenerated.
After that, when the switching element 1U is turned off, the discharge of the floating capacitor 2 ends.

According to the switching operation of the switching elements 1U and 1UN, the charging current flowing through the capacitor 3Un connected in parallel with the switching element 1Un turned on first is small, and the charging current flows in parallel with the switching element 1U1 turned on last. The charging current flowing through the capacitor 3U1 is increased.

Further, the charging current flowing through the capacitor 3U1 connected in parallel to the switching element 1U1 turned off first is large, and the charging current flowing through the capacitor 3Un connected in parallel with the switching element 1Un turned off last is small.

Therefore, the charging current flowing through the capacitor 3UN connected in parallel with the switching element 1UN whose turn-on timing is later and the turn-off timing is earlier tends to increase, and the responsibility tends to increase. By adjusting the capacitance of the capacitor 3UN according to the responsibility, it is possible to suppress heat generation and voltage rise of the capacitor 3UN itself.

FIG. 4 is a diagram for explaining another example of the operation of the first circuit of the power conversion device of one embodiment.
Here, a timing chart showing an example of turn-on timing and turn-off timing between the gate signal Su of the switching element 1U and the gate signal Su (N) of the plurality of switching elements 1UN of the upper arm, and the current flowing through the plurality of capacitors 3UN are shown. An example of the relationship between the icu (N) and the current icf flowing through the floating capacitor 2 is shown. In FIG. 4, the current icu (N) and the current icf are positive in the direction of output from the AC end 212. Further, during the period shown in FIG. 4, the switching element 1X and the plurality of switching elements 1XM of the lower arm are in a state of being turned off.

The operation of the power conversion device of this embodiment is different from that of the first embodiment described above in the order in which the plurality of switching elements 1UN are turned off. In this example, the plurality of switching elements 1UN are turned off in the same order in which the plurality of switching elements 1UN are turned on. For example, in the example shown in FIG. 4, after the switching element 1U is turned on, the switching element 1U1 of the switch circuit 101n is sequentially turned on to the switching element 1U1 of the switch circuit 1011 on the side closer to the inverter cell 100 (the side having the lower potential). , Turns on, and turns off from the switching element 1Un to the switching element 1U1 in the same order. The switching element 1U is turned off after all of the plurality of switching elements 1UN are turned off.

Here, the operation of turning off a plurality of switching elements 1UN will be described.
When the switching element 1U and the switching element 1UN are all turned on, for example, when the switching element 1Un is turned off, the current flowing through the switching element 1Un flows to the capacitor 3Un, and the capacitor 3Un is charged.

The above turn-off operation is sequentially performed from the switching element 1Un to the switching element 1U1. As a result, the energy charged in the capacitor 3Un is sequentially discharged to the capacitor 3U1 and finally charged in the floating capacitor 2.

When the turn-off operation of the plurality of switching elements 1UN is completed, the switching element 1U is turned on, the plurality of switching elements 1UN are all turned off, and the energy charged in the floating capacitor 2 is discharged. As a result, the energy stored in the floating capacitor 2 is efficiently regenerated.

After that, when the switching element 1U is turned off, the discharge of the floating capacitor 2 ends.

According to the switching operation of the switching elements 1U and 1UN, the charging current flowing through the capacitor 3Un connected in parallel to the switching element 1Un that was turned on first was small, and the charging current was connected in parallel to the switching element 1U1 that was turned on last. The charging current flowing through the capacitor 3U1 increases.

Further, the charging current flowing through the capacitor 3Un connected in parallel to the first turned-off switching element 1Un is large, and the charging current flowing through the capacitor 3U1 connected in parallel with the finally turned-off switching element 1U1 is small.

Therefore, the charging currents flowing through each of the plurality of capacitors 3UN are substantially equal, and the responsibilities of the plurality of capacitors 3UN are also substantially equal. As a result, by making the capacitances of the plurality of capacitors 3UN equal, it is possible to suppress heat generation and voltage rise of the capacitors 3UN itself.

From the above, according to the power conversion device of the present embodiment, it is possible to suppress the switching loss without performing high-speed switching as in the example shown in FIG. 3 described above, and the power conversion device can be realized. It is possible to avoid the increase in size.

Hereinafter, an example of the effect of the power conversion device of the present embodiment will be described.
5A to 7B are diagrams for explaining an example of the effect of the power conversion device of one embodiment.
FIG. 5A is a diagram showing an example of loss caused by turning on the switching element in a conventional two-level inverter as a comparative example.
FIG. 5B is a diagram showing an example of a loss caused in the arm when the switching element is turned on in the power conversion device of one embodiment.
FIG. 5C is a diagram showing an example of a loss generated for each element when the switching element is turned on in the power conversion device of one embodiment.

For example, as shown in FIG. 5A, in a conventional two-level inverter, the current flowing through the switching element increases and the voltage applied to the switching element decreases at the timing when the switching element turns on. The energy generated in the switching element due to the current flowing through the switching element and the voltage applied to the switching element becomes heat without being absorbed by other elements, resulting in a switching loss.

On the other hand, in the power conversion device of the present embodiment, as shown in FIG. 5C, when viewed for each switching element, energy is generated at turn-on as in the conventional case, but as shown in FIG. 5B, the entire arm. When viewed as, the energy generated during switching is absorbed by the capacitor 3UN. The energy stored in the capacitor 3UN is discharged to the floating capacitor 2 and regenerated as the discharge energy of the floating capacitor 2. Therefore, of the energy generated when the switching elements 1U and 1UN are turned on, only a part of the energy is lost as the arm as a whole, and the energy efficiency is improved.

FIG. 6A is a diagram showing an example of the loss caused by the turn-off of the switching element in the conventional two-level inverter as a comparative example.
FIG. 6B is a diagram showing an example of a loss caused in the arm due to the switching element turning off in the power conversion device of one embodiment.
FIG. 6C is a diagram showing an example of a loss generated for each element when the switching element is turned off in the power conversion device of one embodiment.

For example, as shown in FIG. 6A, in the conventional two-level inverter, the voltage applied to the switching element increases and the current flowing through the switching element decreases at the timing when the switching element turns off. The energy generated in the switching element due to the current flowing through the switching element and the voltage applied to the switching element becomes heat without being absorbed by other elements, resulting in a switching loss.

On the other hand, in the power conversion device of the present embodiment, as shown in FIG. 6C, when viewed for each switching element, energy is generated at the time of turn-off as in the conventional case, but as shown in FIG. 6B, the entire arm. The energy generated during switching is absorbed by the capacitor 3UN and regenerated as the discharge energy of the floating capacitor 2. Therefore, of the energy generated when the switching elements 1U and 1UN are turned off, only a part of the energy is lost as the arm as a whole, and the energy efficiency is improved.

FIG. 7A is a diagram showing an example of recovery loss generated in a conventional two-level inverter as a comparative example.
FIG. 7B is a diagram showing an example of recovery loss generated in the power conversion device of one embodiment.

For example, as shown in FIG. 7A, in a conventional two-level inverter, when the switching element of the lower arm is turned on, recovery is performed by the current flowing through the parasitic diode and the applied voltage during recovery of the parasitic diode of the switching element of the upper arm. Loss occurs.

On the other hand, in the power conversion device of the present embodiment, when any one of the switching elements 1XM is turned on, for example, as shown in FIG. 7B, the voltage applied to one of the plurality of switch circuits 102M becomes a plurality of voltages. The voltage is divided by the number of series (= n) of the switch circuit 101N and applied to each of the plurality of switch circuits 101N. Therefore, the voltage applied at the time of recovery of the parasitic diode of the switching element 1UN of the plurality of switch circuits 101N becomes small, and the loss (recovery loss) generated at the time of recovery is reduced.

In the present embodiment, the operation of the upper arm (plurality of switch circuits 101N) of the power conversion device has been described, but the same applies to the lower arm (plurality of switch circuits 101M). That is, when the lower arm is turned on, the switching element 1X of the inverter cell 100 is first turned on, and then the plurality of switching elements 1XM are sequentially turned on at predetermined time intervals. When the lower arm is turned off, a plurality of switching elements 1XM are sequentially turned off, and then the switching element 1X of the inverter cell 100 is turned off. This makes it possible to reduce the switching loss and recovery loss of the switching elements 1X and 1XM without switching at high speed.

As described above, according to the power conversion device of the present embodiment, it is possible to suppress the switching loss without performing high-speed switching. Further, in the power conversion device of the present embodiment, a capacitor having a small capacity equivalent to that of a snubber capacitor is used, and it is not necessary to provide a capacitor having a large capacity, so that it is possible to prevent the power conversion device from becoming large in size.

That is, according to the power conversion device of the present embodiment, it is possible to suppress the energy loss to a low level and avoid the increase in size.
In the power conversion device of the present embodiment, high withstand voltage and high dv / dt can be achieved by simultaneously switching a plurality of switching elements 1UN of the upper arm and simultaneously switching a plurality of switching elements 1XM of the lower arm. It is also possible to realize the operation and suppress the surge voltage due to the high di / dt and the parasitic inductance in the capacitor 3UN and the capacitor 3XM.

Further, in the power conversion device of the present embodiment, the output voltage of the power conversion device can be switched to three levels by switching the high withstand voltage switching elements 8pu, 8px, 8nu, 8nx of the high withstand voltage inverter cells 106p and 106n. Therefore, it is possible to further reduce the output power. In this case, the number of series of the switch circuit 101N of the upper arm of the first circuit 300 and the switch circuit 102M of the lower arm can be halved, and the power conversion device can be miniaturized.

Next, the power conversion device of the second embodiment will be described in detail with reference to the drawings.
FIG. 8 is a diagram schematically showing an example of the configuration of the power conversion device of one embodiment.
In the following description, the same reference numerals will be given to the same configurations as those in the first embodiment described above, and the description thereof will be omitted.

The power conversion device of the present embodiment includes a third circuit 500, a fourth circuit 601 and a fifth circuit 602. The third circuit 500, the fourth circuit 601 and the fifth circuit 602 have the same configuration as the first circuit 300 of the first embodiment described above.
The positive terminal of the switch circuit 101n of the fourth circuit 601 is electrically connected to the positive DC end 209. The cell AC terminal 202 of the inverter cell 100 of the fourth circuit 601 is electrically connected to the positive terminal of the switch circuit 101n of the third circuit 500.

The negative terminal of the switch circuit 102m of the fifth circuit 602 is electrically connected to the negative DC end 210. The cell AC terminal 202 of the inverter cell 100 of the fifth circuit 602 is electrically connected to the negative terminal of the switch circuit 102m of the third circuit 500.

The negative terminal of the switch circuit 102m of the fourth circuit 601 and the positive terminal of the switch circuit 101n of the fifth circuit 602 are electrically connected to the intermediate terminal 211.
In the power conversion device of the present embodiment, the fourth circuit 601 and the fifth circuit 602 have the same configuration as the third circuit 500, but are not limited thereto. For example, the fourth circuit 601 and the fifth circuit 602 may have the same configuration as the first circuit 300 of the power conversion device according to any one of the third to ninth embodiments described later, and the fourth circuit 601 and the fifth circuit 602 may have the same configuration. The configuration may be different from that of the five circuits 602.

FIG. 9 is a diagram for explaining an example of the operation of the power conversion device of the second embodiment.
In the present embodiment, the third circuit 500 is connected to the output end (intermediate end of the inverter cell 100) of the fourth circuit 601 and the AC end 212, and the output end of the fifth circuit 602 (intermediate of the inverter cell 100). It operates as a connection switching unit that switches the connection state between the end) and the AC end 212.
In FIG. 9, the gate signal waveforms Su, Su (1) -Su (n), Sx, Sx (1) -Sx (m) of the switching element of the third circuit 500, and the fourth circuit 601 and the fifth circuit 602. An example of the output waveform of only the third circuit 500 combined with the output, the output waveform of the fourth circuit 601 and the fifth circuit 602, and the output waveform of the power conversion device is shown.

In the third circuit 500, the gate signals of the switching element 1U of the inverter cell 100 and the switching element 1UN of the plurality of switch circuits 101N have the same waveform. While the switching element 1U of the third circuit 500 and the plurality of switching elements 1UN are on, the output end and the AC end 212 of the fourth circuit 601 are electrically connected via the third circuit 500. To.

In the third circuit 500, the gate signals of the switching element 1X of the inverter cell 100 and the switching element 1XM of the plurality of switch circuits 102M have the same waveform. While the switching element 1X of the third circuit 500 and the plurality of switching elements 1XM are on, the output end and the AC end 212 of the fourth circuit 602 are electrically connected via the third circuit 500. To.

The fourth circuit 601 and the fifth circuit 602 can realize an arbitrary output voltage waveform by PWM control. In the example shown in FIG. 8, the waveforms of the fourth circuit 601 and the fifth circuit 602 and the output voltage are the differences between the sine wave and the output voltage waveform of the third circuit 500. The fourth circuit 601 and the fifth circuit 602 can generate a gate signal of the upper arm and a gate signal of the lower arm by comparing the voltage command value corresponding to each output voltage with the triangular wave.

As described above, according to the power conversion device of the present embodiment, it is possible to realize an arbitrary output voltage, and the same effect as that of the above-described first embodiment can be obtained. That is, according to the power conversion device of the present embodiment, it is possible to suppress the energy loss to a low level and avoid the increase in size.

Next, the power conversion device of the third embodiment will be described in detail with reference to the drawings.
FIG. 10 is a diagram schematically showing an example of the configuration of the power conversion device of one embodiment.
In the following description, the same components as those of any of the above-described first to second embodiments will be designated by the same reference numerals and description thereof will be omitted.

In the power conversion device of this embodiment, the configuration of the inverter cell 100 of the first circuit 300 is different from that of the first embodiment described above. In the power conversion device of the present embodiment, the first circuit 300 further includes capacitors 3U0, 3X0, diodes 4U0, 4UX, resistors 5U0, 5X0, and regenerative rectifier diodes 6U0, 6X0.

In the diode (upper diode) 4U0, the cathode is electrically connected to the source and the AC end 212 of the switching element 1U, and the anode is electrically connected to the resistor 5U0. It is desirable that the diode 4U0 has fast recovery characteristics with low recovery loss. For example, an element using a Schottky barrier diode (SBD) or a wide bandgap semiconductor (SiC, GaN, etc.) having good recovery characteristics is used. Is desirable.

One end of the capacitor (upper capacitor) 3U0 is electrically connected to the drain of the switching element 1U, and the other end is electrically connected to the anode of the diode 4U0 and the resistor 5U0.

One end of the resistor (upper resistor) 5U0 is electrically connected to the anode of the diode 4U0 and the other end of the capacitor 3U0. The other end of the resistor 5U0 is electrically connected to the anode of the regenerative rectifying diode 6U1 and the cathode of the regenerative rectifying diode 6U0.

In the diode (lower diode) 4X0, the anode is electrically connected to the drain and the AC end 212 of the switching element 1X, and the cathode is electrically connected to the resistor 5X0. It is desirable that the diode 4X0 has fast recovery characteristics with low recovery loss. For example, an element using a Schottky barrier diode (SBD) or a wide bandgap semiconductor (SiC, GaN, etc.) having good recovery characteristics is used. Is desirable.

One end of the capacitor (lower capacitor) 3X0 is electrically connected to the source of the switching element 1X, and the other end is electrically connected to the cathode of the diode 4X0 and the resistor 5XM.
One end of the resistor (lower resistor) 5X0 is electrically connected to the cathode of the diode 4X0 and the other end of the capacitor 3X0. The other end of the resistor 5X0 is electrically connected to the anode of the regenerative rectifying diode 6X0 and the cathode of the regenerative rectifying diode 6X1.

As described above, in the power conversion device of the present embodiment, the upper arm of the inverter cell 100 is a voltage type clamp type switch circuit having the same configuration as the switch circuit 101N, and the lower arm of the inverter cell 100. Is a voltage-type clamp-type switch circuit having the same configuration as the switch circuit 102M. Therefore, in the present embodiment, the upper arm and the lower arm of the inverter cell 100 can use a common circuit as a switch circuit similar to the switch circuits 101N and 102M.

In the present embodiment, the plurality of first-generation rectifier circuits are provided between the first capacitor and the upper capacitor of the first switch circuit on the lowest potential side, and between the upper capacitor and the terminal on the lower potential side of the lower switching element. Is further connected between.

Further, in the present embodiment, the plurality of second-generation rectifier circuits are provided between the second capacitor and the lower capacitor of the second switch circuit on the highest potential side, and on the high potential side of the lower capacitor and the upper switching element. It is further connected to the terminal of.

The operation of the power conversion device of this embodiment is the same as that of the first embodiment described above. That is, in the first circuit 300, the turn-on loss and the turn-off loss are caused by sequentially switching the plurality of switching elements 1UN of the upper arm and the plurality of switching elements 1XM of the lower arm at predetermined time intervals, respectively. In addition, it is possible to reduce losses such as recovery loss.

As described above, according to the power conversion device of the present embodiment, the same effect as that of the above-described first embodiment can be obtained. That is, according to the power conversion device of the present embodiment, it is possible to suppress the energy loss to a low level and avoid the increase in size.

Next, the power conversion device of the fourth embodiment will be described in detail with reference to the drawings.
FIG. 11 is a diagram schematically showing an example of the configuration of the power conversion device of one embodiment.
In the power conversion device of this embodiment, the regenerative rectifier diodes 6U1 and 6X1 of the first circuit 300 are omitted. Further, the anode of the regenerative rectifying diode 6U2 is electrically connected to the cathode of the regenerative rectifying diode 6X2 without being electrically connected to the source of the switching element 1X. The cathode of the regenerative rectifying diode 6X2 is electrically connected to the anode of the regenerative rectifying diode 6U2 without being connected to the drain of the switching element 1U.

That is, the power conversion device of the present embodiment is connected between adjacent switch circuits 101N and between adjacent switch circuits 102M with the direction from the low potential side to the high potential side as the forward direction, and is connected in series with each other. It is provided with a plurality of regenerative rectifying diodes 6UN and 6XM (N = 2 to n, M = 2 to m).

In the present embodiment, the regenerative rectifier circuit is between the first capacitors of the adjacent first switch circuit and between the second capacitors of the adjacent second switch circuit, with the direction from the low potential side to the high potential side as the forward direction. A plurality of regenerative rectifier circuits are connected in series with each other.

That is, in the power conversion device of the present embodiment, at least one of the first switch circuits 101N has a first diode 4UN whose cathode is connected to the low potential side end of the first switching element 1UN, and an anode and a first of the first diode 4UN. When the first capacitor 3UN connected between the 1 switching element 1UN and the high potential side end is provided, the low potential side end of the inverter cell 100 and the low potential side end in the direction from the low potential side to the high potential side are forward directions. It is provided with a regenerative rectifying circuit that connects to the low potential side end of the first capacitor 3UN of the upper arm.

Further, in the power conversion device of the present embodiment, at least one of the second switch circuits 102X has a second diode 4XM in which an anode is connected to the high potential side end of the second switching element 1XM, and a cathode and a second of the second diode 4XM. When the second capacitor 3XM connected between the two switching elements 1XM and the low potential side end is provided, the direction from the low potential side to the high potential side is the forward direction, and the high potential side end of the inverter cell 100 and the high potential side end. It is provided with a regenerative rectifying circuit that connects the high potential side end of the second capacitor 3XM of the lower arm.

In this embodiment, the configuration of the inverter cell 100 may be the same as that of the first embodiment or the same as that of the third embodiment. When the inverter cell 100 has the same configuration as that of the third embodiment, the regenerative rectifying circuit has a forward direction from the low potential side to the high potential side, and the low potential side end of the inverter cell 100 and the upper capacitor 3U0. The low potential side end of the upper arm and the low potential side end of the first capacitor 3UN of the upper arm are connected, and the high potential side end of the inverter cell 100, the high potential side end of the lower capacitor 3X0, and the lower arm. A circuit for connecting the high potential side end of the second capacitor 3XM is provided.

The operation of the power conversion device of this embodiment is the same as that of the first embodiment described above. That is, in the first circuit 300, the turn-on loss and the turn-off loss are caused by sequentially switching the plurality of switching elements 1UN of the upper arm and the plurality of switching elements 1XM of the lower arm at predetermined time intervals, respectively. In addition, it is possible to reduce losses such as recovery loss.

As described above, according to the power conversion device of the present embodiment, the same effect as that of the above-described first embodiment can be obtained. That is, according to the power conversion device of the present embodiment, it is possible to suppress the energy loss to a low level and avoid the increase in size.

Next, the power conversion device of the fifth embodiment will be described in detail with reference to the drawings.
FIG. 12 is a diagram schematically showing an example of the configuration of the power conversion device of one embodiment.
In the following description, the same components as those of any of the above-described first to fourth embodiments will be designated by the same reference numerals and description thereof will be omitted.

The power conversion device of the present embodiment has the fourth aspect described above in that the regenerative rectifier circuit of the first circuit 300 further includes resistors 7C, 7UN (N = 2 to n), and 7XM (M = 2 to m). It is different from the power conversion device of the embodiment.

The resistor 7UN (N = 2 to n) is connected in series with the regenerative rectifier diode 6UN in the path for electrically connecting the snubber terminal 205 (N-1) of the switch circuit 101 (N-1) and the regenerative rectifier diode 6UN. It is connected to the.

The resistor 7XM (M = 2 to m) is connected in series with the regenerative rectifier diode 6XM in the path for electrically connecting the snubber terminal 208M of the switch circuit 102M and the regenerative rectifier diode 6XM.

The resistor 7C is connected in series with the snubber terminal 2051 and the snubber terminal 2081 in a path for electrically connecting the snubber terminal 2051 of the switch circuit 1011 and the snubber terminal 2081 of the switch circuit 1021.

As described above, the power conversion device of this embodiment has a configuration including resistors 7C, 7UN (N = 2 to n), and 7XM (M = 2 to m) connected in series with the regenerative rectifier diodes 6UN and 6XM. Therefore, the number of resistors intervening in the path for electrically connecting the capacitors 3UN and 3XM of the switch circuits 101N and 102M via the snubber terminals 205N and 208M can be reduced. For example, in the configuration shown in FIG. 1, a resistor 5Un and a resistor are connected to a path in which the capacitor 3Un and the capacitor 3U (n-1) are electrically connected via the snubber terminals 205n and 205 (n-1). It is intervened with 5U (n-1). On the other hand, in the configuration shown in FIG. 11, a resistor 7n is provided in a path in which the capacitor 3Un and the capacitor 3U (n-1) are electrically connected via the snubber terminals 205n and 205 (n-1). It is intervening. As a result, the energy charged through the path that electrically connects the switch circuits 101N and the switch circuits 102M can be regenerated more efficiently.

In this embodiment, the configuration of the inverter cell 100 may be the same as that of the first embodiment or the same as that of the third embodiment. When the inverter cell 100 has the same configuration as that of the fifth embodiment, the regenerative rectifying circuit has a forward direction from the low potential side to the high potential side, and the low potential side end of the inverter cell 100 and the upper capacitor 3U0. The low potential side end of the upper arm and the low potential side end of the first capacitor 3UN of the upper arm are connected, and the high potential side end of the inverter cell 100, the high potential side end of the lower capacitor 3X0, and the lower arm. A circuit for connecting the high potential side end of the second capacitor 3XM is provided.

The operation of the power conversion device of this embodiment is the same as that of the first embodiment described above. That is, in the first circuit 300, the turn-on loss and the turn-off loss are caused by sequentially switching the plurality of switching elements 1UN of the upper arm and the plurality of switching elements 1XM of the lower arm at predetermined time intervals, respectively. In addition, it is possible to reduce losses such as recovery loss.

As described above, according to the power conversion device of the present embodiment, the same effect as that of the above-described first embodiment can be obtained. That is, according to the power conversion device of the present embodiment, it is possible to suppress the energy loss to a low level and avoid the increase in size.

Next, the power conversion device of the sixth embodiment will be described in detail with reference to the drawings.
FIG. 13 is a diagram schematically showing an example of the configuration of the power conversion device of one embodiment.
In the following description, the same components as those of any of the above-described first to fourth embodiments will be designated by the same reference numerals and description thereof will be omitted.

The power conversion device of the present embodiment has a configuration in which the first circuit 300 further includes a regenerative rectifier diode 6C in the power conversion device of the fourth embodiment described above.
The regenerative rectifier diode 6C is connected in series with the resistor 7C in the path for electrically connecting the snubber terminal 2051 of the switch circuit 1011 and the resistor 7C.

Further, in the power conversion device of the present embodiment, the resistor 7XM is connected in series with the regenerative rectifier diode 6XM between the regenerative rectifier diode 6XM and the snubber terminal 208 (M-1) of the switch circuit 102 (M-1). It is connected.
The power conversion device of the present embodiment has the same configuration as the power conversion device of the fifth embodiment except for the above configuration.

In the present embodiment, as in the fifth embodiment described above, the number of resistors interposed in the path for electrically connecting the capacitors 3UN and 3XM of the switch circuits 101N and 102M via the snubber terminals 205N and 208M is reduced. be able to. As a result, the energy charged through the path that electrically connects the switch circuits 101N and the switch circuits 102M can be regenerated more efficiently.

In this embodiment, the configuration of the inverter cell 100 may be the same as that of the first embodiment or the same as that of the third embodiment. When the inverter cell 100 has the same configuration as that of the third embodiment, the regenerative rectifying circuit has a forward direction from the low potential side to the high potential side, and the low potential side end of the inverter cell 100 and the upper capacitor 3U0. The low potential side end of the upper arm and the low potential side end of the first capacitor 3UN of the upper arm are connected, and the high potential side end of the inverter cell 100, the high potential side end of the lower capacitor 3X0, and the lower arm. A circuit for connecting the high potential side end of the second capacitor 3XM is provided.

The operation of the power conversion device of this embodiment is the same as that of the first embodiment described above. That is, in the first circuit 300, the turn-on loss and the turn-off loss are caused by sequentially switching the plurality of switching elements 1UN of the upper arm and the plurality of switching elements 1XM of the lower arm at predetermined time intervals, respectively. In addition, it is possible to reduce losses such as recovery loss.

As described above, according to the power conversion device of the present embodiment, the same effect as that of the above-described first embodiment can be obtained. That is, according to the power conversion device of the present embodiment, it is possible to suppress the energy loss to a low level and avoid the increase in size.

Next, the power conversion device of the seventh embodiment will be described in detail with reference to the drawings.
FIG. 14 is a diagram schematically showing an example of the configuration of the power conversion device of one embodiment.
In the following description, the same components as those of any of the above-described first to sixth embodiments will be designated by the same reference numerals and description thereof will be omitted.

In the power conversion device of the present embodiment, the configuration of the lower arm of the first circuit 300 is different from that of the first embodiment described above.
In the power conversion device of the present embodiment, the switching element 1XH is connected to the path between the negative terminal of the first circuit 300 (negative terminal 207 m of the switch circuit 102 m) and the inverter cell 100. As the switching element 1XH, it is desirable to use an element having a higher withstand voltage than the switching element 1UN of the switch circuit 101N. Further, in FIG. 13, although the power conversion device includes one switching element 1XH in the lower arm, a plurality of switching elements 1XH may be connected in series in the lower arm. Although the power conversion direction is unidirectional, the lower arm may be provided with a high withstand voltage diode (passive semiconductor element) instead of the switching element 1XH.

As described above, in the power conversion device of the present embodiment, the configuration of the lower arm is different from that of the first embodiment, and at least one of the first switch circuits 101N is on the low potential side of the first switching element 1UN. When the first diode 4UN having a cathode connected to the end and the first capacitor 3UN connected between the anode of the first diode 4UN and the high potential side end of the first switching element 1UN are provided, and the first At least one of the two-switch circuits 102X is between the second diode 4XM in which the anode is connected to the high potential side end of the second switching element 1XM, and the cathode of the second diode 4XM and the low potential side end of the second switching element 1XM. When at least one of the second capacitor 3XM connected to is provided, the direction from the low potential side to the high potential side is the forward direction, and the low potential side end of the inverter cell 100 and the first capacitor of the upper arm are provided. It is provided with a regenerative rectifying circuit that connects at least one of the low potential side end of 3UN, the high potential side end of the inverter cell 100, and the high potential side end of the second capacitor 3XM of the lower arm.

In this embodiment, the configuration of the inverter cell 100 may be the same as that of the first embodiment or the same as that of the third embodiment. When the inverter cell 100 has the same configuration as that of the third embodiment, the regenerative rectifying circuit has a forward direction from the low potential side to the high potential side, and the low potential side end of the inverter cell 100 and the upper capacitor 3U0. It is provided with a circuit for connecting the low potential side end of the inverter cell 100 and the low potential side end of the first capacitor 3UN of the upper arm, and connecting the high potential side end of the inverter cell 100 and the high potential side end of the lower capacitor 3X0.

In the power conversion device of the present embodiment, the upper arm operates in the same manner as in the first embodiment described above, and the lower arm switches the switching element 1X and the switching element 1XH at the same time, so that the lower arm is the same as the conventional two-level inverter. It is possible to operate. Therefore, in the power conversion device of the present embodiment, losses such as turn-on loss, turn-off loss, and recovery loss are reduced by sequentially switching the plurality of switching elements 1UN of the upper arm at predetermined time intervals. It is possible.

As described above, according to the power conversion device of the present embodiment, the same effect as that of the above-described first embodiment can be obtained. That is, according to the power conversion device of the present embodiment, it is possible to suppress the energy loss to a low level and avoid the increase in size.

Next, the power conversion device of the eighth embodiment will be described in detail with reference to the drawings.
FIG. 15 is a diagram schematically showing an example of the configuration of the power conversion device of one embodiment.
In the following description, the same components as those of any of the above-described first to seventh embodiments will be designated by the same reference numerals and description thereof will be omitted.

In the power conversion device of this embodiment, the configuration of the upper arm of the first circuit 300 is different from that of the first embodiment described above.
In the power conversion device of the present embodiment, the switching element 1UH is connected to the path between the positive terminal of the first circuit 300 (the positive terminal 203n of the switch circuit 101n) and the inverter cell 100. As the switching element 1UH, it is desirable to use an element having a higher withstand voltage than the switching element 1XM of the switch circuit 102M. Further, in FIG. 14, although the power conversion device includes one switching element 1UH on the upper arm, a plurality of switching elements 1UH may be connected in series on the upper arm. Although the power conversion direction is unidirectional, the upper arm may be provided with a high withstand voltage diode (passive semiconductor element) instead of the switching element 1UH.

As described above, in the power conversion device of the present embodiment, the configuration of the upper arm is different from that of the first embodiment, and at least one of the first switch circuits 101N is on the low potential side of the first switching element 1UN. When the first diode 4UN having a cathode connected to the end and the first capacitor 3UN connected between the anode of the first diode 4UN and the high potential side end of the first switching element 1UN are provided, and the first At least one of the two-switch circuits 102X is between the second diode 4XM in which the anode is connected to the high potential side end of the second switching element 1XM, and the cathode of the second diode 4XM and the low potential side end of the second switching element 1XM. When at least one of the second capacitor 3XM connected to is provided, the direction from the low potential side to the high potential side is the forward direction, and the low potential side end of the inverter cell 100 and the first capacitor of the upper arm are provided. It is provided with a regenerative rectifying circuit that connects at least one of the low potential side end of 3UN, the high potential side end of the inverter cell 100, and the high potential side end of the second capacitor 3XM of the lower arm.

In this embodiment, the configuration of the inverter cell 100 may be the same as that of the first embodiment or the same as that of the third embodiment. When the inverter cell 100 has the same configuration as that of the fifth embodiment, the regenerative rectifier circuit has the low potential side end of the inverter cell 100 and the upper capacitor 3U0 in the forward direction from the low potential side to the high potential side. A circuit is provided for connecting the low potential side end of the inverter cell 100, the high potential side end of the lower capacitor 3X0, and the high potential side end of the second capacitor 3XM of the lower arm.

In the power conversion device of this embodiment, the lower arm operates in the same manner as in the first embodiment described above, and the upper arm switches the switching element 1U and the switching element 1UH at the same time, so that the upper arm is the same as the conventional two-level inverter. It is possible to operate. Therefore, in the power conversion device of the present embodiment, losses such as turn-on loss, turn-off loss, and recovery loss are reduced by sequentially switching the plurality of switching elements 1XM of the lower arm at predetermined time intervals. It is possible.

As described above, according to the power conversion device of the present embodiment, the same effect as that of the above-described first embodiment can be obtained. That is, according to the power conversion device of the present embodiment, it is possible to suppress the energy loss to a low level and avoid the increase in size.

Next, the power conversion device of the ninth embodiment will be described in detail with reference to the drawings.
FIG. 16 is a diagram schematically showing an example of the configuration of the power conversion device of one embodiment.
In the following description, the same components as those of any of the above-described first to eighth embodiments will be designated by the same reference numerals and description thereof will be omitted.

In the power conversion device of this embodiment, the configuration of the regenerative rectifier circuit of the first circuit 300 is different from that of the first embodiment described above.
Each of the plurality of first regenerative rectifier circuits includes a regenerative rectifier diode 6 UN and a resistor 5 UN. The regenerative rectifying diode 6UN is connected between the negative cell terminal 201 and the snubber terminal 205N with the direction from the negative cell terminal 201 of the inverter cell 100 toward the snubber terminal 205N of the switch circuit 101N as the forward direction. The resistor 5UN is connected in series with the regenerative rectifier diode 6UN in a path that electrically connects the cathode of the regenerative rectifier diode 6UN and the snubber terminal 205N. That is, the anodes of the plurality of regenerative rectifying diodes 6UN are electrically connected to the negative cell terminal 201 of the inverter cell 100 without passing through another regenerative rectifying diode 6UN.

That is, in the present embodiment, the plurality of first-generation rectifier circuits have a terminal on the low potential side of the lower switching element (the low potential side end of the inverter cell 100) with the direction from the low potential side to the high potential side as the forward direction. ) And the low potential side ends of the first capacitors of the plurality of first switch circuits, respectively.

As described above, in the power conversion device of the present embodiment, at least one of the first switch circuits 101N has a first diode 4UN whose cathode is connected to the low potential side end of the first switching element 1UN, and a first diode 4UN. When the first capacitor 3UN connected between the anode and the high potential side end of the first switching element 1UN is provided, and at least one of the second switch circuits 102X is the high potential side end of the second switching element 1XM. At least one of when the second diode 4XM having an anode connected to the second diode 4XM and the second capacitor 3XM connected between the cathode of the second diode 4XM and the low potential side end of the second switching element 1XM is provided. When, with the direction from the low potential side to the high potential side as the forward direction, the low potential side end of the inverter cell 100, the low potential side end of the first capacitor 3UN of the upper arm, and the high potential side end and the lower side of the inverter cell 100. It is provided with a regenerative rectifying circuit that connects at least one of the high potential side end of the second capacitor 3XM of the arm.

Each of the plurality of second regenerative rectifier circuits includes a regenerative rectifier diode 6XM and a resistor 5XM. The regenerative rectifying diode 6XM is connected between the snubber terminal 208M and the positive cell terminal 200 with the direction from the snubber terminal 208M of the switch circuit 102M toward the positive cell terminal 200 of the inverter cell 100 as the forward direction. The resistor 5XM is connected in series with the regenerative rectifier diode 6XM in a path for electrically connecting the anode of the regenerative rectifier diode 6XM and the snubber terminal 208M. That is, the cathodes of the plurality of regenerative rectifying diodes 6XM are electrically connected to the positive cell terminals 200 of the inverter cell 100 without passing through other regenerative rectifying diodes 6XM.

That is, in the present embodiment, the plurality of second-generation rectifier circuits have the terminal on the high potential side of the upper switching element (the high potential side end of the inverter cell 100) with the direction from the low potential side to the high potential side as the forward direction. Is connected to each of the high potential side ends of the second capacitors of the plurality of second switch circuits.

In this embodiment, the configuration of the inverter cell 100 may be the same as that of the first embodiment or the same as that of the third embodiment. When the inverter cell 100 has the same configuration as that of the third embodiment, the regenerative rectifier circuit has the low potential side end of the inverter cell 100 and the upper capacitor 3U0 in the forward direction from the low potential side to the high potential side. Further includes a circuit connected between the low potential side end of the inverter cell 100 and a circuit connected between the high potential side end of the inverter cell 100 and the high potential side end of the lower capacitor 3X0.

In the power conversion device of the present embodiment, the switching operation of the switching elements 1U and 1X, the plurality of switching elements 1UN, and the plurality of switching elements 1XM is the same as that of the above-described first embodiment. That is, the plurality of switching elements 1UN of the upper arm and the plurality of switching elements 1XM of the lower arm are sequentially switched at predetermined time intervals, respectively.

In the present embodiment, due to the switching operation and the configuration of the regenerative rectifying diodes 6UN and 6XM, the energy stored in the capacitors 3UN and 3XM of the switch circuits 101N and 102M floats without passing through the plurality of regenerative rectifying diodes 6UN and 6XM. The capacitor 2 is charged.

Therefore, according to the power conversion device of the present embodiment, it is possible to reduce losses such as turn-on loss, turn-off loss, and recovery loss, and a path for discharging energy from the capacitors 3UN and 3XM to the floating capacitor 2. In, the loss of energy is reduced, and energy can be regenerated more efficiently.

In the power conversion device of the present embodiment, since the voltage applied to the regenerative rectifier diodes 6UN and 6XM is higher than that of the circuit configuration of the power conversion device of the first embodiment described above, the regenerative rectifier diodes 6UN and 6XM are used. It is desirable to apply an element with a higher withstand voltage than that of the first embodiment.

As described above, according to the power conversion device of the present embodiment, the same effect as that of the above-described first embodiment can be obtained. That is, according to the power conversion device of the present embodiment, it is possible to suppress the energy loss to a low level and avoid the increase in size.

Although some embodiments of the present invention have been described, these embodiments are presented as examples and are not intended to limit the scope of the invention. These novel embodiments can be implemented in various other embodiments, and various omissions, replacements, and changes can be made without departing from the gist of the invention. These embodiments and modifications thereof are included in the scope and gist of the invention, and are also included in the scope of the invention described in the claims and the equivalent scope thereof.

1U, 1X, 1UH, 1XH, 1UN, 1XM ... Switching element, 1UNU, 1XMU ... Positive side switching element, 1UNL, 1XML ... Negative side switching element, 2 ... Floating capacitor, 3UN, 3XM ... Condenser, 4UN, 4XM ... Diode, 5U, 5UN, 5XM ... resistor, 6, 6C, 6UN, 6XM ... regenerative rectifying diode, 7C, 7UN, 7XM ... resistor, 8pu, 8px, 8nu, 8nx ... high withstand voltage switching element, 9p, 9n ... DC capacitor, 100 ... Inverter cell, 101N, 102M ... Switch circuit, 106p, 106n, 601, 602 ... High withstand voltage inverter cell, 209 ... Positive DC end, 210 ... Negative DC end, 211 ... Intermediate terminal, 212 ... AC terminal (AC) End), 300 ... 1st circuit, 400 ... 2nd circuit, 500 ... 3rd circuit, 601 ... 4th circuit, 602 ... 5th circuit.

Claims (9)

An upper high withstand voltage inverter cell that is electrically connected to the positive DC end at the high potential side end and electrically connected to the intermediate end at the low potential side end.
A lower high withstand voltage inverter cell that is electrically connected to the intermediate end at the high potential side end and electrically connected to the negative DC end at the low potential side end.
An upper switching element connected between the AC end and the high potential side end, a lower switching element connected between the AC end and the low potential side end, and a high potential side end and a low potential side end. An inverter cell having an upper switching element and a floating capacitor connected in parallel to the lower switching element between them.
An upper arm connected between the high potential side end of the inverter cell and the output end of the upper high withstand voltage inverter cell, and one or a plurality of first switch circuits having a first switching element connected in series. ,
A lower arm connected between the low potential side end of the inverter cell and the output end of the lower high withstand voltage inverter cell, and one or a plurality of second switch circuits having a second switching element are connected in series. And with
The upper high withstand voltage inverter cell and the lower high withstand voltage inverter cell are connected between the upper high withstand voltage switching element connected between the high potential side end and the output end and between the low potential side end and the output end. It is provided with a lower high withstand voltage switching element and a DC capacitor connected between the high potential side end and the low potential side end.
At least one of the first switch circuits includes a first diode having a cathode connected to the low potential side end of the first switching element, an anode of the first diode, and a high potential side end of the first switching element. When it has a first capacitor connected between them, it has a first-generation rectifying circuit that connects the low-potential side end of the inverter cell and the low-potential side end of the first capacitor.
At least one of the second switch circuits includes a second diode having an anode connected to the high potential side end of the second switching element, a cathode of the second diode, and a low potential side end of the second switching element. When it has a second capacitor connected between them, it has a second regenerative rectification circuit that connects the high potential side end of the inverter cell and the high potential side end of the second capacitor. Converter. An upper switching element connected between the AC end and the high potential side end, a lower switching element connected between the AC end and the low potential side end, and a high potential side end and a low potential side end. A first inverter cell having an inverter cell having a floating capacitor connected in parallel to the upper switching element and the lower switching element in between, and a first switching element connected to the high potential side end of the inverter cell and having a first switching element. The upper arm configured by connecting one or more switch circuits in series and the second switch circuit connected to the low potential side end of the inverter cell and having the second switching element are connected in series one or more. Includes a third circuit, a fourth circuit, and a fifth circuit with a lower arm.
Each of the third circuit, the fourth circuit, and the fifth circuit includes a first diode in which at least one of the first switch circuits has a cathode connected to the low potential side end of the first switching element, and the first diode. When it has a first capacitor connected between the anode of the first diode and the high potential side end of the first switching element, the low potential side end of the inverter cell and the low potential side of the first capacitor are provided. It has a first-generation rectifier circuit that connects to the end,
At least one of the second switch circuits includes a second diode having an anode connected to the high potential side end of the second switching element, a cathode of the second diode, and a low potential side end of the second switching element. When it has a second capacitor connected between them, it has a second regenerative rectification circuit that connects the high potential side end of the inverter cell and the high potential side end of the second capacitor.
The fourth circuit is electrically connected to the positive DC end at the high potential side end, electrically connected to the intermediate end at the low potential side end, and the high potential side of the third circuit at the AC end. Electrically connected to the end,
The fifth circuit is electrically connected to the intermediate end at the high potential side end, electrically connected to the negative DC end at the low potential side end, and at the low potential side end of the third circuit at the AC end. A power converter characterized by being electrically connected to. The first-generation rectifier circuit is connected between one or more first-generation rectifier diodes connected in series, the cathode of the one first-generation rectifier diode, and the low-potential side end of the first capacitor. It has a first resistor or a plurality of first resistors connected between the cathodes of the plurality of first-generation rectifier diodes and the corresponding low-potential side ends of the first capacitor.
The second-generation rectifier circuit is connected between one or more second-generation rectifier diodes connected in series, the anode of the one second-generation rectifier diode, and the high-potential end of the second capacitor. Claim 1 or claim having two resistors, or a plurality of second resistors connected between the anodes of the plurality of second-generation rectifier diodes and the corresponding high potential side ends of the second capacitor, respectively. Item 2. The power conversion device according to Item 2. The second switching element of the second switch circuit connected in one or more series has a higher withstand voltage than the first switching element, or the first switch circuit of the first switch circuit connected in series one or more. The power conversion device according to claim 1 or 2, wherein the switching element has a higher withstand voltage than the second switching element. The power conversion device according to claim 3, further comprising a first inductance element in place of the first resistor and a second inductance element in place of the second resistor. The inverter cell includes an upper diode having a cathode connected to the low potential side end of the upper switching element, and an upper capacitor connected between the anode of the upper diode and the high potential side end of the upper switching element. A lower diode having an anode connected to the high potential side end of the lower switching element, and a lower capacitor connected between the cathode of the lower diode and the low potential side end of the lower switching element. With
The first regenerative rectifier circuit further connects the low potential side end of the upper capacitor and the low potential side end of the inverter cell.
The second regenerative rectifier circuit according to any one of claims 1 to 5, wherein the high potential side of the lower capacitor and the high potential side end of the inverter cell are further connected. The power converter described. Claims 1 to 2, wherein the first switching element, the second switching element, the upper switching element, and the lower switching element each include a plurality of switching elements connected in series. The power conversion device according to any one of 6. The plurality of the first switching elements and the plurality of the second switching elements are sequentially switched at predetermined time intervals.
In the upper arm, the capacitances of the plurality of first capacitors are turned on and then turned off more than the first capacitors connected to the first switching element, which have a shorter period from turn-on to turn-off. The first capacitor connected to the first switching element, which takes a long time to be used, is small.
In the lower arm, the capacitances of the plurality of second capacitors are turned on and then turned off more than the second capacitors connected to the second switching element, which have a shorter period from turn-on to turn-off. The power conversion device according to claim 1 or 2, wherein the second capacitor connected to the second switching element having a long period of time is small. An upper switching element connected between the AC end and the high potential side end, a lower switching element connected between the AC end and the low potential side end, and a high potential side end and a low potential side end. An inverter cell having an upper switching element and a floating capacitor connected in parallel to the lower switching element between them.
An upper arm connected to the high potential side end of the inverter cell and configured by connecting one or more first switch circuits having a first switching element in series.
A lower arm connected to the low potential side end of the inverter cell and configured by connecting one or more second switch circuits having a second switching element in series.
With
At least one of the first switch circuits includes a first diode having a cathode connected to the low potential side end of the first switching element, an anode of the first diode, and a high potential side end of the first switching element. Has a first capacitor connected between
At least one of the second switch circuits includes a second diode having an anode connected to the high potential side end of the second switching element, a cathode of the second diode, and a low potential side end of the second switching element. Has a second capacitor connected between
A first-generation rectifier diode connected in series with one or a plurality of low-potential side ends of the inverter cell and the low-potential side end of the first capacitor, a cathode of the one first-generation rectifier diode, and the first one. A first resistor connected to the low potential side end of one capacitor, or connected between the cathodes of a plurality of the first regenerative rectifier diodes and the corresponding low potential side end of the first capacitor, respectively. A first-generation rectifier circuit having a plurality of first resistors,
A second regenerative rectifier diode connected in series with one or a plurality of high potential side ends of the inverter cell and the high potential side end of the second capacitor, an anode of the one second regenerative rectifier diode, and the first. A second resistor connected to the high potential side end of the two capacitors, or connected between the anodes of the plurality of second regenerative rectifier diodes and the corresponding high potential side end of the second capacitor, respectively. A second-generation rectifier circuit having a plurality of second resistors and
The low potential side end of the first capacitor of the first switch circuit on the lowest potential side and the high potential side end of the second capacitor of the second switch circuit on the highest potential side are directly connected. A power converter characterized by being connected via a resistor or via a resistor and a regenerative rectifying diode.