Flying-Capacitor Multilevel-Konverter

Abstract

Flying-capacitor multilevel converter, comprising: two input ports; and at least one phase leg circuit, each of the at least one phase leg circuit comprising: a first group of at least two controllable semiconductor switches connected in series and a second group of at least two controllable semiconductor switches connected in series, each controllable semiconductor switch being provided with a driver configured to drive a control terminal of the respective controllable semiconductor switch, the first group and the second group being connected in series between the two input terminals of the converter; a phase output terminal connected to a node connecting the first group to the second group; at least one first capacitor, each of the at least one first capacitor being individually connected between a node connecting two adjacent controllable semiconductor switches of the first group and a node connecting two adjacent controllable semiconductor switches of the second group; and a power supply arrangement for the drivers of the controllable semiconductor switches, the power supply arrangement comprising at least two power supplies, each power supply being configured to supply power to at least one driver, and each power supply being configured to be supplied by a voltage across at least one controllable semiconductor switch.

Description

FIELD OF THE INVENTIONThe present invention relates to a flying capacitor multilevel converter.BACKGROUNDThe flying capacitor multilevel converter topology with low-voltage MOSFETs can, for example, bring about a considerable weight reduction of the converter. The concept can be used for various applications such as photovoltaic converters (PV), UPS systems, high-speed drives and battery storage systems (BESS) in a broad power range, for example from single-phase 3 kW to three-phase 300 kW systems.The topology may be realized, for example, by a large number (e.g., up to 48) of low voltage MOSFETs (e.g., 150 V), low voltage GaN HEMTs (e.g., 100 V), or other types of controllable semiconductor switches and corresponding gate driver circuits, or generally drivers or driver circuits. Since these drivers may be at different voltage levels, isolated power supplies or power supply circuits are usually required to supply the supply voltages for the individual drivers of the controllable semiconductor switches. However, such isolated power supplies for the drivers may cause considerable extra costs, especially when the number of levels of topology used is high, and also require a lot of space.A further alternative is the use of so-called cascaded bootstrap circuits to supply a plurality of drivers via bootstrap diodes from a single current source. However, a disadvantage of such a cascaded bootstrap circuit is that each bootstrap diode causes a voltage drop of, for example, approximately 1 V and therefore the semiconductor switches at the end of the bootstrap circuit chain have a significantly lower control voltage than the initial supply voltage of the current source.BRIEF DESCRIPTIONAn object of the present invention is therefore to provide an apparatus for overcoming the above problems or at least alleviating the above problems. The object of the invention is achieved by a flying capacitor multilevel converter characterized by what is stated in the independent claim. The preferred embodiments of the invention are disclosed in the dependent claims.The invention is based on the idea of supplying the drivers with energy via power supplies, the energy of which is provided by a voltage via at least one controllable semiconductor switch. In other words, the energy for the driver power supply is obtained from voltage differences of the flying capacitors of the converter, which occur via the controllable semiconductor switches in the flying capacitor multilevel converter topology.An advantage of the solution according to the invention is that the drivers of a flying capacitor multilevel converter can be supplied without isolated power supplies and with sufficient voltages, for example even at a higher number of stages in the converter.BRIEF DESCRIPTION OF THE DRAWINGSThe invention will be described in more detail below on the basis of preferred embodiments with reference to the accompanying drawings, in which FIG. 1 shows an example of a converter circuit according to an embodiment; FIG. 2 shows diagrams according to an embodiment; FIG. 3 shows an example of a circuit according to an embodiment; FIG. 4 shows an example of a converter circuit according to an embodiment; FIG. 5 shows a diagram according to an embodiment; FIG. 6 shows an example of a circuit according to an embodiment; FIG. 7 shows an example of a circuit according to an embodiment FIG. 8 shows an example of a converter circuit according to an embodiment; and FIG. 9 shows an example of a three-phase converter circuit according to an embodiment.DETAILED DESCRIPTIONThe following embodiments are exemplary. Although reference is made in the specification to "a", "an" or "some" embodiment(s) in several places, this does not necessarily mean that each of these references refers to the same embodiment(s) or that the feature applies to only a single embodiment, for example. Individual features of various embodiments may also be combined to obtain other embodiments. In general, all terms and expressions used should be interpreted broadly and serve to illustrate, not to limit, the embodiments. The figures only show components necessary for understanding the various embodiments. The number and / or configuration of the various elements and generally their implementation may vary from the examples shown in the figures. The application of the various embodiments described herein is not limited to a particular system, but may be used in conjunction with various electrical systems. Moreover, the use of the various embodiments described herein is not limited to systems that use, for example, a particular fundamental frequency or voltage level.FIG. 1 shows an example of a converter circuit according to an embodiment. According to an embodiment, a flying capacitor multilevel converter comprises two input terminals (poles) Vdc+, Vdc-. The input terminals Vdc+, Vdc- may be powered by a suitable direct current source (not shown in the figures), e.g. a photovoltaic (PV) power generation system having one or more photovoltaic panels. Another example of a possible DC power source is a wind power generation system, e.g. a wind farm, which may comprise one or more wind generators, e.g. driven by one or more wind turbines. Other types of DC power sources or combinations thereof may also be used, such as a fuel cell DC power source or a battery backed DC power source. The flying capacitor multilevel converter comprises at least one phase shifter circuit 100. The number of such phase branch circuits 100 in the converter may be any, e.g. one, two, three, four or more. For the sake of simplicity, only one such phase shifter circuit 100 is illustrated in FIG. 1. Moreover, the number of stages of the flying capacitor multilevel converter may vary and may be, for example, two, three, four, five or more.According to an embodiment, each of the at least one phase leg circuit comprises a first group of at least two series-connected controllable semiconductor switches and a second group of at least two series-connected controllable semiconductor switches. In addition, the first group and the second group are connected in series between the input terminals of the converter, and a phase output terminal is connected to a node connecting the first group to the second group. In the example of FIG. 1, the example phase shifter circuit 100 includes a first group (upper arm) of four series-connected controllable semiconductor switches S 11, S 12, S 13, S 14 and a second group (lower arm) of four series-connected controllable semiconductor switches S 21, S 22, S 23, S 24, these groups being connected in series between both input terminals Vdc+, Vdcof the converter. A phase output terminal (e.g., AC phase) Voutis connected to node A, which connects the first group to the second group. The number of series-connected controllable semiconductor switches in each of these groups may be two or any number greater than two, e.g., three, four, five, six, seven, eight, nine or more. According to one embodiment, the number of controllable semiconductor switches in the first group is equal to the number of controllable semiconductor switches in the second group of the (respective) phase shifter circuit 100. The controllable semiconductor switches S 11, S 12, S 13, S 14, S 21, S 22, S 23, S 24 may be transistors, e.g. metal oxide semiconductor field effect transistors (MOSFETs), high electron mobility transistors (HEMTs), e.g. gallium nitride HEMTs (GaN), or insulated gate bipolar transistors (IGBTs), or thyristors or other controllable semiconductor switches. The nominal voltage of the controllable semiconductor switches may vary and may be selected based on, e.g., the system configuration and / or the application. The controllable semiconductor switches can be, for example, low-voltage devices (generally with a rated voltage <600 V), for example with a rated voltage of 60 V, 80 V, 100 V, 150 V or 200 V, or high-voltage devices. The controllable semiconductor switches may be connected in series with their connected terminals in a manner known per se, e.g. as illustrated in the example of FIG. 1. The term "switched terminals" refers here generally to drain and source terminals or emitter and collector terminals, for example, depending on the type of controllable semiconductor switches. In the example of FIG. 1, the drains are connected to the positive input terminal Vdc+ and the sources are connected to the negative input terminal Vdc-. In addition to the switched terminals, the controllable semiconductor switches S 11, S 12, S 13, S 14, S 21, S 22, S 23, S 24 have a third terminal, which is referred to herein as a control terminal. The term control terminal refers here generally to e.g. a gate terminal or a base terminal, depending on what type of controllable semiconductor switches it is and via which control terminal the switching function of the controllable semiconductor switch can be controlled. The controllable semiconductor switches S 11, S 12, S 13, S 14, S 21, S 22, S 23, S 24 may be provided with corresponding anti-parallel diodes, as shown in the example of FIG. 1. According to one embodiment, each controllable semiconductor switch is provided with a driver 20 (gate drive) which is configured to drive the control terminal of the respective controllable semiconductor switch. Accordingly, in the example of FIG. 1, the phase shifter circuit 100 comprises a driver 20 for each of the controllable semiconductor switches S 11, S 12, S 13, S 14, S 21, S 22, S 23, S 24. The driver is generally understood to mean a circuit or a component (device, device, unit) with which the respective controllable semiconductor switch can be controlled via the control terminal of the controllable semiconductor switch in a manner known per se. The execution of the drivers 20 depends on the controllable semiconductor switches S 11-S 24. It should be noted that the control of the controllable semiconductor switches of such a flying capacitor multilevel converter r as such can be implemented in various ways and is known as such to a person skilled in the art and therefore need not be explained in more detail here. For example, such a flying capacitor multilevel converter could be controlled with a suitable pulse width modulation (PWM) scheme and used as an inverter. Further control connections, for example for controlling the drivers 20, or further control arrangements therefor have also been omitted in the figures for the sake of clarity.According to an embodiment, each of the at least one phase leg circuit 100 further comprises at least one first capacitor, wherein each of the at least one first capacitors is individually connected between a node connecting two adjacent controllable semiconductor switches of the first group and a node connecting two adjacent controllable semiconductor switches of the second group, respectively. In the example of FIG. 1, there are three first capacitors, i.e. flying capacitors, C fc, so that each of them is individually connected between a node connecting two adjacent controllable semiconductor switches of the first group and a node connecting two adjacent controllable semiconductor switches of the second group, respectively. According to an embodiment, each such node connecting two adjacent controllable semiconductor switches of the first group, e.g. the nodes between the controllable semiconductor switches S 11 and S 12, between the controllable semiconductor switches S 12 and S 13 and between the controllable semiconductor switches S 13 and S 14, is connected to a node connecting two adjacent controllable semiconductor switches of the second group, e.g. B. the nodes between controllable semiconductor switches S 21 and S 22, between controllable semiconductor switches S 22 and S 23, and between controllable semiconductor switches S 23 and S 24, are connected by a respective flying capacitor C(fc). Consequently, the number of flying capacitors C may be fc( n-2) / 2, where n is the number of controllable semiconductor switches S 11-S 24. The term capacitor as used herein generally refers to an element or circuit having capacitance, and such a capacitor may include, for example, one or more capacitor components (units, devices).According to an embodiment, each of the at least one phase leg circuit 100 further comprises a power supply arrangement for the drivers 20 of the controllable semiconductor switches S 11-S 24, wherein the power supply arrangement comprises at least two power supplies, wherein each power supply arrangement is configured to supply power to at least one driver, and wherein each power supply arrangement is configured to be supplied with a voltage via at least one controllable semiconductor switch. As used herein, the term power supply generally refers to a circuit or component (device, device, unit) that can be used to power one or more drivers 20, preferably with a suitable (e.g., predetermined) voltage level or voltage level range. According to an embodiment, the voltage supply may comprise a voltage regulator. The voltage level or voltage level range of the output of the power supply 10 may depend on the type of driver 20 and / or the controllable semiconductor switch, for example. Such a power supply 10 may comprise a DC power supply, such as a DC / DC power supply (a DC / DC converter), configured to generate a predetermined, preferably regulated, output voltage or voltage range. The output voltage supplied from the power supply 10 to the driver 20, e.g. in the case of MOSFETs, could be about 12 V, e.g. between about 9 V and about 15 V. In the example of FIG. 1, there is a power supply 10 (supply circuit) for each of the drivers 20, i.e. a power supply 10 supplies power to a driver 20. However, such a power supply 10 could also provide power to more than one driver 20, as described further below. In the example of FIG. 1, each of the power supplies 10 is supplied with power by a voltage via a corresponding controllable semiconductor switch. According to an embodiment, the input terminals of the power supplies may be connected to the switched terminals of the one controllable semiconductor switch. Accordingly, in the example of FIG. 1, an input of each of the power supplies 10 is connected to the switched terminals of a respective controllable semiconductor switch, wherein the voltage across the respective controllable semiconductor switch, i.e. between its switched terminals, is connected to the input of the power supply 10. Thus, the voltage differences of the flying (first) capacitors C fc, e.g. between terminals of two capacitors or between a capacitor and one of the two input terminals Vdc+, Vdc- acting via the controllable semiconductor switches S 11-S 24, can be used to supply the power supplies 10. According to an embodiment, the power supply arrangement may comprise at least two power supplies for the first group connected in series between the two input terminals Vdc+, Vdc- of the converter and at least two power supplies for the second group connected in series between the two input terminals Vdc+, Vdc- of the converter. For example, as shown in the example of FIG. 1, the power supplies 10 may be connected in series between the two input terminals Vdc+, Vdc- of the converter, i.e., the inputs of the power supplies 10 may be connected in series between the two input terminals Vdc+, Vdc- of the converter. It is also possible that the power supplies are not connected in series, as shown in an example below.An idea of the above-described general embodiment is therefore the principle of directly obtaining the power (energy) for the drivers 20 power supplies 10 from the voltage differences of the flying capacitors C fc. The concept may be the more effective the higher the number of stages of the converter and / or the lower the voltage difference between the flying capacitors C is fc. During normal operation of the flying capacitor multilevel converter, the voltage difference between two adjacent flying capacitors seen at a controllable semiconductor switch when it is switched off is typically a pulsed voltage, since the controllable semiconductor switches are repeatedly switched on and off during normal operation. Therefore, the energy for the driver circuit can be buffered, for example, in a (small) buffer capacitor. In standby operation of the converter (all controllable semiconductor switches are off), the voltage difference between two adjacent flying capacitors C fc is a DC voltage, which can be stabilized, e.g., by a precharge resistor network (if present). Nevertheless, it is possible to obtain essentially directly from such voltage differences sufficient power for feeding the individual driver power supply units 10, since the flying capacitors C fc thus function as energy sources. The amount of energy drawn from the flying capacitors can be negligibly small and thus has no appreciable influence on the voltage compensation, for example of the flying capacitors themselves. The voltage compensation may normally be provided, for example, by a natural compensation or by active compensation principles. FIG. 2 shows the voltages at two controllable semiconductor switches of the circuit of the example of FIG. 1. more precisely, alternative a) of FIG. 2 shows the pulsed voltage across the controllable semiconductor switch S 13 and alternative b) of FIG. 2 shows the pulsed voltage across the controllable semiconductor switch S 22. In normal operation, all controllable semiconductor switches in a flying capacitor multilevel converter switch continuously. Whenever a controllable semiconductor switch is switched off for a moment, the voltage difference of two flying capacitors is available across the relevant controllable semiconductor switch. During this period, the voltage difference may be used to charge an intermediate buffer capacitor with a sufficient amount of energy required for the driver of the corresponding controllable semiconductor switch, for example. Some possible embodiments for obtaining the energy from the voltage differences of the flying capacitors are described in more detail below.According to an embodiment, the power supply 10 includes a resistor and a zener diode connected in series between the input terminals of the power supply, and a diode connected between a node connecting the resistor and the zener diode and an output terminal of the power supply. FIG. 3 shows an example of a power supply according to this embodiment. In the example, a possible internal configuration of the power supply 10 in conjunction with a controllable semiconductor switch S and its driver 20 is shown separately. In the example, the power supply 10 includes a resistor R s and a zener diode D (z), which are connected in series between the input terminals in 1 (positive) and in 2 (negative) of the power supply 10, and a diode D, which is connected between a node connecting the resistor R s and the zener diode D z and an output terminal out 1 of the power supply 10. Moreover, according to an embodiment, the power supply 10 may include a (second) capacitor C b connected between the output terminals out 1 (positive) and out 2 (negative) of the power supply 10, as also illustrated in the example. The values of the components in the exemplary configuration of the power supply 10 may be selected as appropriate, for example, based on the required voltage to be supplied to the driver 20. For example, if an operating voltage of about 12 V is to be provided from the output out 1, out 2 of the power supply 10 to the driver 20, the zener diode D z could be a 12-V zener diode and the diode could be a small signal diode (e.g., <15 V). FIG. 4 shows an example of a converter circuit according to an embodiment corresponding to that of FIG. 1, in which each of the power supplies 10 has the exemplary configuration shown in FIG. 3.The exemplary configuration of the power supply 10 with the series resistor R s, the zener diode D z and the (small signal) diode described above may be used to supply the required voltage, e.g., about 12 V, to the driver 20, e.g., a MOSFET gate driver, to supply a MOSFET gate driver substantially directly from the voltage occurring across the controllable semiconductor switch S (e.g., one of the switches S 11-S 24), which may be, for example, a voltage difference between two adjacent flying capacitors C fc or a voltage difference between a flying capacitor C fc and one of the input terminals (poles) Vdc+ and Vdc-. An additional effect is that such a combination of a zener diode D z and a series resistor R s may form a pre-charge resistor network for the flying capacitor multilevel converters. For example, it may be necessary to pre-charge the flying capacitors C fc to their rated voltages during the startup of the flying capacitor multilevel converter. This can be easily accomplished with a resistor network which directly charges the capacitors from the DC link circuits Vdc+, Vdc-. Such a resistor network is therefore readily present in the exemplary embodiment of the power supply illustrated in FIGS. 3 and 4 and described above. Depending on the power consumed by the driver 20 and the voltage difference across the controllable semiconductor switch S, such a power supply 10 may have additional losses in the series resistors R s. However, the higher the number of stages of the flying capacitor multilevel converter and / or the lower the voltage class of the controllable semiconductor switch(s) S, the lower the voltage and the more effective the solution becomes, since the losses in the series resistor / resistors en R resulting therefrom are reduced. FIG. 5 illustrates a diagram according to one embodiment. The diagram shows a situation where the power supply configuration shown in the example of FIG. 3 is simulated in a flying capacitor topology with 150 V and 100 V MOSFETs as controllable semiconductor switches S and a realistic power consumption of the driver 20. The simulated driver supply voltage is shown in FIG. 5. The ripple of the supply voltage (3%) can be reduced either by a reduction of the series resistance R s or by an increase of the buffer capacity C b which has an effect on the loss balance, for example. Two different configurations were simulated with 150V and 100V MOSFETs, a buffer capacitance C b of 50 μF and a switching frequency of 24 kHz. The resulting losses per series resistance for the 150 V-MOSFET configuration were 0.27 W. For the 100 V-MOSFET configuration, the losses were reduced to 0.18 W per series resistance. In the standby state (all controllable semiconductor switches are switched off), the current consumption of the driver(s) 20 falls to 2.5 mA. The total intermediate circuit voltage can be substantially uniformly divided among all controllable semiconductor switches S, S 11-S 24, such that the voltage at the power supplies 10 can be reduced by 50%, but still sufficient to supply the leakage current of the driver(s) 20, for example. The losses in the series resistors substantially correspond to the losses during normal operation of the converter.According to another embodiment, the power supply comprises a low dropout regulator. According to an embodiment, the power supply further comprises a diode and a third capacitor connected in series between the input terminals of the power supply. FIG. 6 shows an example of a power supply according to this embodiment. In the example, a possible internal configuration of the power supply 10 in conjunction with a controllable semiconductor switch S and its driver 20 is shown separately. In the example, the power supply 10 comprises a low dropout (LDO) regulator 11, i.e. a type of linear DC regulator, with which the voltage supplied to the input in 1, in 2 of the power supply 10 can be regulated to an appropriate level in order to be output from the output out 1, out 2 of the power supply 10 to the driver 20. The exemplary configuration further includes a diode D s, which is preferably a Schottky diode, and a (third) capacitor C s, which is connected in series between the input terminals in 1, in 2 of the power supply 10, such that the capacitor C s is connected between the input terminals of the regulator 11. In addition, the power supply 10 according to an embodiment may comprise a (second) capacitor C b connected between the output terminals out 1, out 2 of the power supply 10, as also illustrated in the example of FIG. 6. The values of the components in the exemplary configuration of the power supply 10 may be selected as appropriate, for example, based on the required voltage supplied to the driver 20. The diode n D could be n z. B. may be a 150V Schottky diode. An advantage of the configuration of the power supply 10 according to this embodiment is a possibly more stable output voltage of the power supply 10 and / or the value of the required buffer capacitance C b could be reduced compared to the configuration with the zener diode in the example of FIG. 3, for example.According to another embodiment, the power supply comprises a switching regulator. According to an embodiment, the power supply further comprises a diode and a third capacitor connected in series between the input terminals of the power supply. FIG. 7 shows an example of a power supply according to this embodiment. In the example, a possible internal configuration of the power supply 10 in conjunction with a controllable semiconductor switch S and its driver 20 is shown separately. In the example, the power supply 10 comprises a switching regulator (switching regulator) 12, i.e. a type of DC regulator, with which the voltage supplied to the input in 1, in 2 of the power supply 10 can be regulated using one or more switching elements to a suitable level, which is output from the output out 1, out 2 of the power supply 10 to the driver 20. The exemplary configuration further includes a diode D s, which is preferably a Schottky diode, and a (third) capacitor C s, which is connected in series between the input terminals in 1, in 2 of the power supply 10 such that the capacitor C s is connected between the input terminals of the regulator 12. Moreover, according to an embodiment, the power supply 10 may comprise a (second) capacitor C b connected between the output terminals out 1, out 2 of the power supply 10, as also illustrated in the example of FIG. 6. In addition, a small filter inductor L, e.g., a surface mount device (SMD), or a ferrite bead could be used in the output of the switching regulator 12, as shown in FIG. 7. The values of the components in the exemplary configuration of the power supply 10 may be selected appropriately depending on the required voltage supplied to the driver 20. The diode n D could be n z. B. may be a 150V Schottky diode. An advantage of the configuration of the power supply 10 according to this embodiment is that it may have lower losses, for example.According to an embodiment, each power supply 10 is configured to be supplied with a voltage across (only) one controllable semiconductor switch S, S 11-S 24 and individually supply power to a respective driver 20 of the respective controllable semiconductor switch. Thus, according to one embodiment, there could be a separate power supply 10 for each of the drivers 20, as shown, for example, in the examples of FIGS. 1 and 4.According to another embodiment, each power supply 10 is configured to be supplied with a voltage across (only) one controllable semiconductor switch S, S 11-S 24, and at least one power supply 10 is configured to supply power to a respective driver of the respective controllable semiconductor switch and a driver of at least one other controllable semiconductor switch. The at least one other controllable semiconductor switch may comprise at least one adjacent controllable semiconductor switch. According to an embodiment, each power supply 10 is configured to be supplied with the voltage via a controllable semiconductor switch S, S 11-S 24 and to supply power to the respective driver 20 of the respective controllable semiconductor switch and a driver of at least one other controllable semiconductor switch.FIG. 8 shows an example in which each of the power supplies 10 is supplied with the voltage via a controllable semiconductor switch, respectively. Moreover, in this example, each of the power supplies 10 supplies the respective driver 20 of the respective controllable semiconductor switch and additionally the driver 20 of another controllable semiconductor switch which is adjacent to the respective controllable semiconductor switch via which the voltage of the power supply 10 is supplied. Generally, each of the power supplies 10 may supply power to one or more drivers 20. In other words, it is thus possible to combine the power supply according to each embodiment described here in different ways with the bootstrap concept. For example, such a combined topology could be used for high power drivers to reduce the number of switching regulators when power supplies 10 are implemented with switching regulators.FIG. 9 shows an example of a three-phase flying capacitor multilevel converter circuit according to an embodiment. The example three-phase flying capacitor multilevel converter circuit comprises three phase leg circuits 100A, 100B, 100C, which may be implemented according to any of the embodiments described herein or according to any combination of the embodiments described herein. For reasons of clarity, the drivers of the controllable semiconductor switches S 11, S 12, S 13, S 14, S 21, S 22, S 23, S 24 or the power supplies of the drivers are not illustrated in FIG. 9. The DC inputs of the three-phase branch circuits 100A, 100B, 100C are connected in parallel with the input terminals (poles) Vdc+, Vdc- of the converter, and the respective AC outputs VoutA, VoutB, VoutC of the three-phase branch circuits 100A, 100B, 100C provide a three-phase AC output of the converter with a three-phase AC voltage v ac. The number of such phase branch circuits 100A, 100B, 100C in a polyphase flying capacitor multilevel converter may be any number, e.g. two, three, four, five, six or more.It is obvious to the person skilled in the art that the inventive concept can be implemented in various ways as the technical progress proceeds. The invention and its embodiments are not limited to the examples described above, but may vary within the scope of the claims.References included in the specificationThis list of documents cited by the applicant has been produced in an automated manner and is only included for the better information of the reader. The list is not part of the German patent application or utility model application. The DPMA does not take any adhesion for any faults or omissions.Cited Non-Patent LiteratureSemiconductor switches S, S 11-S 24

[0020]

Claims

A flying capacitor multilevel converter comprising: two input terminals; and at least one phase leg circuit, wherein each of the at least one phase leg circuit comprises: a first group of at least two series-connected controllable semiconductor switches and a second group of at least two series-connected controllable semiconductor switches, wherein each controllable semiconductor switch is provided with a driver configured to drive a control terminal of the respective controllable semiconductor switch, wherein the first group and the second group are series-connected between the two input terminals of the converter; a phase output terminal connected to a node connecting the first group to the second group; at least one first capacitor, each of the at least one first capacitors being individually connected between a node connecting two adjacent controllable semiconductor switches of the first group and a node connecting two adjacent controllable semiconductor switches of the second group, respectively; and a power supply arrangement for the drivers of the controllable semiconductor switches, wherein the power supply arrangement comprises at least two power supplies, wherein each power supply is configured to supply power to at least one driver, and wherein each power supply is configured to be supplied by a voltage across at least one controllable semiconductor switch.The flying capacitor multilevel converter of claim 1, wherein each power supply is configured to be supplied by a voltage via a controllable semiconductor switch and individually supply power to a respective driver of the respective controllable semiconductor switch.The flying capacitor multilevel converter of claim 1, wherein each power supply is configured to be supplied with a voltage via a controllable semiconductor switch, and at least one power supply is configured to supply power to a respective driver of the respective controllable semiconductor switch and a driver of at least one other controllable semiconductor switch.The flying capacitor multilevel converter according to claim 1 or 2, wherein the power supply arrangement comprises at least two power supplies for the first group connected in series between the two input terminals of the converter and at least two power supplies for the second group connected in series between the two input terminals of the converter.The flying capacitor multilevel converter according to any one of claims 2 to 4, wherein the input terminals of the power supply are connected to the switching terminals of the one controllable semiconductor switch.The flying capacitor multilevel converter of any of claims 1 to 5, wherein the power supply comprises a voltage regulator.The flying capacitor multilevel converter according to any one of claims 1 to 6, wherein the power supply comprises a resistor and a zener diode connected in series between input terminals of the power supply, and a diode connected between a node connecting the resistor and the zener diode and an output terminal of the power supply.The flying capacitor multilevel converter capacitor of claim 7, wherein the power supply further comprises a second capacitor connected between the output terminals of the power supply.The flying capacitor multilevel converter according to any of claims 1 to 6, wherein the power supply comprises a low dropout regulator.The flying capacitor multilevel converter according to any one of claims 1 to 6, wherein the power supply comprises a switching regulator.The flying capacitor multilevel converter of claim 9 or 10, wherein the power supply further comprises a second capacitor connected between the output terminals of the power supply.The flying capacitor multilevel converter of claim 9, 10 or 11, wherein the power supply further comprises a diode and a third capacitor connected in series between the input terminals of the power supply.The flying capacitor multilevel converter according to any one of claims 1 to 12, wherein the number of controllable semiconductor switches of the first group is equal to the number of controllable semiconductor switches of the second group.The flying capacitor multilevel converter according to any one of claims 1 to 13, comprising two, three, four or more phase leg circuits.

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