KR20230126642A - Hybrid modular multilevel converter (hmmc) based on a neutral point pilot (npp) topology - Google Patents

Abstract

A hybrid modular multilevel converter (HMMC) based on a neutral point pilot (NPP) topology and having an ABC N-phase structure is provided. The HMMC includes N pairs of identical upper and lower arms, each upper and lower arm consisting of X submodules and Y switch sets. The switches in each set are cascaded and connected in series, each submodule consists of a full bridge silicon (Si) insulated gate bipolar transistor (IGBT) converter, and at least one of the switch sets consists of an IGBT of opposite polarity.

Description

Hybrid modular multilevel converter (HMMC) based on neutral point pilot (NPP) topology {HYBRID MODULAR MULTILEVEL CONVERTER (HMMC) BASED ON A NEUTRAL POINT PILOT (NPP) TOPOLOGY}

This application, filed on February 23, 2022, “Hybrid MMC Built-based on 3-level NPP with variable DC link voltage (lower than AC) and FB-SMC capable of DC link short circuit protection /Based-On Three Level NPP with FB-SMS Capable of Variable (Lower) DC Link (than AC) Voltage and DC Link Short-Circuit Protection)” asserted, the disclosure of this US application is hereby incorporated by reference in its entirety.

The following disclosure relates generally to a modular multilevel converter (MMC) based on a neutral point pilot (NPP) or neutral point clamped (NPC) topology. .

Existing MMCs are modular and scalable, removing technical barriers to extending power converters to higher voltage and higher power applications. Additionally, MMC provides a convenient path to improve power quality by increasing the conversion level.

By way of example, and as understood by those skilled in the art, a two-level converter is considered a basic MMC building block. For higher voltage and power quality applications, the conversion level can be increased (beyond 2-levels) depending on the voltage level that needs to be manipulated or how many waveforms will be superimposed together to create the desired waveform or power quality. .

In general, the higher the number of conversion levels, the higher the power quality performance. Classic state-of-the-art typically includes 2-level, 3-level, or 5-level converters. Increasing the number of transform levels increases the flexibility to create better waveforms with minimal filtering and post-processing.

Typically, a combination of 2-level and 3-level converters or two 3-level converters together are used to create 5 levels of conversion. Typically, insulated-gate bipolar transistor (IGBT) devices are used as combinable and scalable modules (described in detail below) to create desired conversion levels. This concept is the foundation of the existing MMC.

However, one drawback for higher voltage and better quality power applications is that conventional MMCs have a larger footprint/volume, heavier weight, and use a larger number of submodules (SMs), making them more compact. that it is expensive For stationary utility or power grid applications, larger volume and heavier weight may not be an issue. However, for power applications (eg, ship propulsion), volume, weight, and power density become important requirements in addition to cost.

In view of the foregoing drawbacks, hybrid MMC (HMMC) requires systems and methods to reduce footprint/volume, weight, and cost compared to existing MMC solutions. These methods and systems should maintain the modularity, scalability, and power quality performance of existing MMCs.

In certain circumstances, an embodiment includes an HMMC based on an NPP topology and having an ABC N-topic structure. The HMMC includes N pairs of identical upper and lower arms, each upper and lower arm consisting of X submodules and Y switch sets. The switches in each set are cascaded and connected in series, each submodule consists of a full-bridge silicon (Si) IGBT converter, and at least one of the switch sets consists of IGBTs of opposite polarity.

Embodiments provide an HMMC built on a 3-level neutral point pilot (3-level NPP) converter topology capable of DC link voltage lower than the AC source/input voltage and with DC link short isolation protection. The lower DC link voltage is provided through a unique HMMC active front-end (AFE) built on a 3L-NPP converter topology using a full-bridge sub-module (FB-SM). A pair of IGBTs cascaded in series with opposite polarity is also used.

An HMMC configured according to an embodiment maintains the modularity, scalability, and power quality performance of existing MMCs while reducing volume, weight, and cost compared to existing MMC solutions.

Embodiments overcome problems associated with larger volume, heavier weight, and higher cost associated with existing MMCs. Embodiments hybridize existing MMC SMs with 3L-NPP converter topologies and component/subsystem technologies.

Additional features, modes of operation, advantages, and other aspects of various embodiments are described below with reference to the accompanying drawings. It should be noted that this disclosure is not limited to the specific embodiments described herein. These examples are presented for illustrative purposes only. Additional embodiments or variations of these disclosed embodiments will be apparent to those skilled in the relevant art(s) based on the teachings provided.

Exemplary embodiments may take the form of various components and arrangements of components. BRIEF DESCRIPTION OF THE DRAWINGS Exemplary embodiments are shown in the accompanying drawings, and like reference numbers throughout may indicate corresponding or like parts in the various drawings. The drawings are for illustrative purposes only and should not be construed as limiting the present disclosure. Given the following possible description of the drawings, new aspects of the present disclosure will become apparent to those skilled in the relevant art(s).
1 illustrates a block diagram of an exemplary system for performing power conversion in accordance with an embodiment of the present disclosure.
2A shows a block diagram of an exemplary FB-SM with silicon (Si) IGBTs according to an embodiment.
2B shows a block diagram of an exemplary FB-SM having a silicon carbide (SiC) metal oxide semiconductor field effect transistor (MOSFET) according to an embodiment.
3 shows a block diagram of an exemplary hybrid FB-SM (HFB-SM) with Si IGBTs according to an embodiment.
4A shows a block diagram of an exemplary half-bridge SM (HB-SM) with Si IGBTs according to an embodiment.
4B shows a block diagram of an example HB-SM with a SiC MOSFET according to an embodiment.
5 shows a block diagram of a prior art two-level MMC.
6A shows a block diagram of a prior art 3-level active neutral-point clamped (ANPC) MMC.
6B-6D show block diagrams of a 3-level ANPC MMC replacing switches with submodules in accordance with various embodiments of the present disclosure.
7A shows a block diagram of a 3-level ANPC based HMMC using anti-blocking switches of opposite polarity according to an embodiment.
Figure 7b shows a block diagram of a 3-level NPP based HMMC using an anti-blocking switch of opposite polarity according to an embodiment.
7C shows a detailed block diagram of a 3-level NPP based HMMC using an anti-block switch at each phase arm branch according to an embodiment.

Although specific embodiments for specific applications are described herein, it should be understood that the disclosure is not limited thereto. Those skilled in the art having access to the teachings provided herein will recognize additional applications, variations, and embodiments within the scope of the present disclosure and additional fields in which it will find significant utility.

1 includes a system 100 for converting electrical power. In one embodiment, system 100 includes a source 102 , a power converter 104 , and a source/load 106 . The term source as used herein refers to renewable power sources, non-renewable power sources, generators, grids, fuel cells, energy storage (when discharged), and the like. Also, the term load as used herein may refer to a motor, electrical appliance, energy storage (when recharged), and the like.

Also, the power converter 104 may be a multi-level converter. In one embodiment, source 102 may be operatively connected to a first terminal (not shown) of power converter 104 . A second terminal (not shown) of power converter 104 may be operatively connected to source/load 106 . The first terminal and the second terminal may be alternately used as an input terminal or an output terminal of the power converter 104 .

System 100 further includes a controller 108 . Controller 108 is configured to control operation of power converter 104 . By way of example only and not limitation, the controller 108 may be configured to control the operation of the power converter 104 by controlling the switching of a plurality of semiconductor switches and sub-modules SM within the power converter 104 .

As mentioned above as background, the 2-level converter is a basic component of MMC. As the number of conversion levels increases, a 3-level converter or a 5-level converter depending on the number of required voltage levels can be used. For example, achieving more than 7, 9, 10 levels requires true converter modularity. This modularity is achieved using building blocks, traditionally referred to as submodules (SMs).

SM can be implemented using full bridge (FB) converters. The FB converter includes four semiconductor switches and one smoothing capacitor for energy storage/buffer/filter. SM can also be implemented using a half-bridge (HB) converter that includes two semiconductor switches.

2A is a block diagram of an exemplary two-level FB-SM 200 according to an embodiment. The exemplary two-level FB-SM 200 of FIG. 2A includes semiconductor switches 204a to 204d and a smoothing capacitor 206 . In one embodiment, switches 204a-204d are formed of Si IGBTs.

2B is a block diagram of an exemplary two-level FB-SM 202 based on SiC MOSFETs. The 2-level FB-SM 202 includes SiC MOSFET switches 208a to 208d and a smoothing capacitor 210.

The HMMC topology enables the use of low voltage FB-SM. As a result, a SiC MOSFET rated at 1.7 kV as an example becomes a viable option. Other viable options include IGBTs with various voltage ratings. For example, in another embodiment of the present disclosure, the semiconductor switches (e.g., 204a through 204d) may be field effect transistors (FETs), injection enhanced gate transistors (IEGTs), gallium nitride based switches, gallium arsenide based switches, or equivalents thereof.

With FB-SM, it provides isolation protection in case of a DC link short fault, as well as the option of superimposing the negative voltage (SM capacitor) or subtracting the voltage to obtain a DC link voltage lower than the AC input voltage. . For example, when the IGBTs are in the OFF state, two IGBTs connected with opposite polarity can block the higher AC voltage from feeding back into the DC link, causing control stability issues.

3 is a block diagram of an exemplary two-level hybrid FB-SM (HFB-SM) 300 with Si IGBTs according to an embodiment. The HFB-SM 300 includes a smoothing capacitor 306 and semiconductor switches 304a to 304d. Switches 304a to 304d are formed of mixed diodes with Si IGBTs or SiC MOSFETs (not shown in FIG. 3). As in the case of FIGS. 2A and 2B above, both options can be used as SM. Various other embodiments and alternatives are described in more detail below.

As mentioned above, the SM semiconductor switch can be implemented as FB or HB. For example, the FB-SM 200 may be implemented as an HB-SM by removing the right side of the FB-SM 200 of FIG. 2A. The right side of the FB-SM 200 basically forms the exemplary two-level HB-SM 400 shown in FIG. 4A. That is, the HB-SM 400 may be implemented with the Si IGBT semiconductor switches 204a to 204b and the capacitor 206 of the FB-SM 200 of FIG. 2A.

In the same manner, FIG. 4B is a block diagram of an exemplary two-level HB-SM 402 implemented using the SiC MOSFET switch on the right side of the FB-SM 202 . That is, the HB-SM 402 may be implemented with the semiconductor switches 204a to 204b and the capacitor 206 of the FB-SM 202 of FIG. 2B.

The various combinations of two-level SMs shown in FIGS. 2A-4B can be connected in series to create any desired number of conversion levels in a conventional MMC. 5 is a block diagram of a prior art or classic two-level MMC 500 described using a plurality of two-level SMs connected in series.

In FIG. 5, the classical MMC 500 has an ABC 3-phase structure including positive and negative DC voltage rails 502 and 504, respectively. Positive rail 502 and negative rail 504 form DC terminal 505 . Each of the 3-phases A, B, and C corresponds to one of phase legs 506, 508, and 510. Phase legs 506, 508, and 510 are connected to AC terminals 512A, 512B, and 512C, respectively.

As an example, phase leg 510 includes an upper arm 516A and an identical lower arm 516B. In the example of FIG. 5 , upper arm 516A and lower arm 516B are connected together on one lead to AC terminal 512C and include arm inductors 518A and 518B for current suppression, respectively. Upper arm 516A and lower arm 516B are connected to positive rail 502 and negative rail 504 respectively on opposite leads.

The description of phase leg 510 applies equally to phase legs 506 and 508 . The upper and lower arms of each phase leg 506, 508, and 510 include serially connected two-level submodules SM1 to SMn. Each of the two-level submodules SM1 to SMn is a full bridge converter (eg, FB-SM 200 in FIG. 2A) or a half bridge converter (eg, HB-SM 400 in FIG. 4A).

In the MMC 500, the number of serially connected SMs may be increased to increase the number of conversion levels. That is, more SMs can be added to provide better and more precise power quality waveforms. Thus, to meet various converter requirements, designers only need to select the appropriate number of SMs and build the MMC into a larger converter with higher voltage, higher power, and better power quality performance.

However, the problem is that as more SMs are used in the MMC to achieve more levels, the corresponding cost, weight, footprint or size increases. For stationary MMC applications such as electrical grids, this drawback has little impact.

For example, in electrical grid applications, there is usually sufficient physical space to accommodate more essential equipment components and applicable line replaceable units (LRUs). On the other hand, in ship propulsion, aviation, and similar power applications, weight and volume become important considerations.

Embodiments of the present disclosure hybridize prior art MMC SMs using a 3-level NPP or 3-level NPC converter topology to address the larger volume, heavier weight, and higher cost problems associated with prior art MMCs. overcome

More specifically, the embodiment provides a novel HMMC topology approach that includes a mixture of both controllable semiconductor switches and submodules within each phase arm of a 3-level NPP or 3-level NPC MMC. For example, instead of using submodules in an existing 2-level MMC containing 100% submodules, the embodiment uses a 3-level basic structure MMC. Each of the corresponding upper and lower arms of each phase includes a suitable mixture of semiconductor switches and submodules (eg, 50% switches and 50% submodules).

6A is a block diagram of a prior art three-level active neutral point clamped (ANPC) converter 600. ANPC converter 600 is provided as an introduction to the new HMMC topology disclosed herein.

ANPC converter 600 includes an ABC 3-phase structure that includes positive and negative DC voltage rails 602 and 604, respectively. Positive rail 602 and negative rail 604 form DC terminal 606 . Each of the three-phases A, B, and C includes corresponding phase legs 608, 610, and 612. Phase legs 608, 610, and 612 are connected to AC terminals 614A, 614B, and 614C, respectively, and form AC side 616. ANPC converter 600 includes a DC midpoint node 620.

Phase leg 608 includes upper and lower arms 618A and 618B, respectively, along with arm inductors 619A and 619B. As an example, upper arm 618A includes one switch 622A and another switch 624A for actively controlling and coupling midpoint node 620 to midpoint node 620 . Also included is a third switch 626A. Symmetrical to upper arm 618A, lower arm 618B includes switches 622B, 624B, and 626B.

In the 3-level ANPC converter 600 based on the HMMC topology of the embodiment, the switches of the upper arm 618A and the lower arm 618B may be replaced with one or more SMs as shown in the embodiment of FIGS. 6B to 6D. there is. HMMCs constructed in this way retain the modularity, scalability, and power quality performance of existing MMCs while reducing volume, weight, and cost compared to existing MMC solutions.

As an example, in the embodiment of FIG. 6B , HMMC 600-1 includes switch 626A in upper arm 618A of phase leg 608 ( FIG. 6A ), including SM1-A and SM2-A. Replace with a pair of SMs (626A-1). Similarly, lower arm 618B replaces switch 626B with a pair of SMs 626B-1 comprising SM1-B and SM2-B. The remaining phase legs 610 and 612 are symmetrical with respect to phase leg 608 and reflect the corresponding replacement of individual switches with submodules. For the purpose of modularity uniformity, the SMs in an arrangement such as SM1-A and SM2-A in a pair of SMs 626A-1 are generally substantially the same value. However, certain embodiments may require SM1-A and SM2-A, or other SMs in a similar arrangement, to be unequal (eg, mixed) values.

In the embodiment of FIG. 6C , exemplary HMMC 600-2 includes switch 624A in upper arm 618A of phase leg 608 ( FIG. 6A ), a pair including SM1-A and SM2-A. Replaced with SM (624A-2) of Similarly, lower arm 618B replaces switch 624B with a pair of SMs 624B-2, including SM1-B and SM2-B. The remaining phase legs 610 and 612 are symmetrical with respect to phase leg 608 and reflect the corresponding replacement of individual switches with submodules.

In the embodiment of FIG. 6D , exemplary HMMC 600-3 includes switch 622A in upper arm 618A of phase leg 608 (FIG. 6A), a pair including SM1-A and SM2-A. Replaced with SM (622A-3) of Similarly, lower arm 618B replaces switch 622B with a pair of SMs 622B-3, including SM1-B and SM2-B. The remaining phase legs 610 and 612 are symmetrical with respect to phase leg 608 and reflect the corresponding replacement of individual switches with submodules.

7A shows a block diagram of another embodiment of the present disclosure. In FIG. 7A, a three-level ANPC HMMC 700 replaces a single switch, such as one of switches 622A, 624A, and 626A in FIG. 6A, with two non-blocking switches connected in series and with opposite polarity. For example, ANPC HMMC 700 includes an anti-blocking pair 702 of switches 702A and 702B of opposite polarity connected in series. An advantage of this configuration is that when the submodule 704 is a half bridge, the opposite polarity switches 702A and 702B block the higher voltage from the AC side 706 from being fed back to the DC link, providing short-circuit isolation protection. that it provides

With an introduction and focus on the NPP concept, FIG. 7B shows a block diagram of a further embodiment of the present disclosure. The embodiment of FIG. 7B using the NPP HMMC 710 provides similar isolation functionality as the ANPC HMMC 700 of FIG. 7A. For example, the NPP HMMC 710 includes an anti-blocking pair 714 of switches 714A and 714B connected in series with opposite polarity, depending on the embodiment. As achieved in the ANPC converter 700 of FIG. 7A, the NPP HMMC 710 also ensures that the higher voltage from the AC side 706 is fed back to the DC link when the SM 712 is an HB-SM. configured to block.

FIG. 7C shows a detailed block diagram of a 3-level NPP HMMC 730 that shares similarities with the NPP converter 710 of FIG. 7B. However, as described in more detail below, NPP HMMC 730 provides a pair of anti-block switches on both branches of the phase arm. Accordingly, the NPP HMMC 730 also provides short-circuit blocking of the DC link using the anti-blocking switch when the SM is HB-SM.

For convenience and not limitation only, the anti-disconnect switch is shown only in FIGS. 7A-7C. However, it should be noted that the concept of using an anti-blocking switch to prevent higher voltages from the AC side from being fed back to the DC link applies equally to the exemplary embodiment of FIGS. 6B-6D.

Additionally, the 3-level NPP HMMC 730 includes a mixture of both SMs and switches in all upper and lower arms of the phase leg. That is, in the HMMC 730, only a portion (eg, 30%, 40%, 50%, etc.) of semiconductor switches used in equivalent multilevel converters are replaced with SMs.

The mixture of semiconductor switches and SMs (i.e., HMMC topology) shown in the embodiment of FIG. 7c provides many of the beneficial properties of classical MMCs, including modularity. However, the exemplary NPP HMMC 730 is smaller in volume, lighter in weight, and less expensive than classical MMCs, but can achieve equal or better power quality performance.

The example HMMC 730 of FIG. 7C includes a positive DC voltage rail 731 and a negative DC voltage rail 732 . AC side 733 includes AC output terminals 734A, 734B, and 734C corresponding to AC phases A, B, and C, respectively. AC phase legs 736, 738, and 740 also correspond to AC phases A, B, and C, respectively, and are electrically connected to neutral point 742. Although the ABC structure of HMMC 730 represents three AC phases, the embodiment can be applied to systems containing (N) AC phases.

Phase legs 736, 738, and 740 are coupled between positive rail 731 and negative rail 732. Phase legs 736, 738, and 740 each include an upper arm and a lower arm. For example, phase leg 736 includes an upper arm 744A and a lower arm 744B. Although the discussion below focuses on upper arm 744A, the concepts discussed apply equally to the upper and lower arms of phase legs 738 and 740 as well as lower arm 744B.

HMMC 730 includes DC link capacitors C1 and C2. The leads of each of capacitors C1 and C2 are connected together at neutral point 742. Opposite leads of capacitors C1 and C2 are connected to positive rail 731 and negative rail 732, respectively.

As shown in FIG. 7C , upper arm 744A includes a first pair of semiconductor switches 746 cascaded and connected in series, preferably of opposite polarity. One lead of this switch pair 746 is connected to AC voltage terminal 734A and the other lead is connected to neutral point 742. Upper arm 744A also includes a second semiconductor switch pair 748 shown with opposite polarity. Although this semiconductor switch pair 748 is shown with reversed polarity, the embodiment is not so limited. The open lead of this switch pair 748 is connected to the positive rail 731.

Upper arm 744A also includes a plurality of serially connected SMs 750, thus introducing a hybrid approach of mixing SMs and semiconductor switches within the upper and lower arms of the MMC phase leg. In various embodiments, SM 750 may be an HB-SM. One lead of the serially connected SMs 750 is connected to a lead of a switch pair 748 and the other lead is connected to a female inductor 754. The other lead of female inductor 754 is connected to AC terminal 734A.

In the example of FIG. 7B , SM 750 may be a full bridge or half bridge topology. For example, if SM 750 is an HB-SM, switches 748 will preferably be of opposite polarity to provide the blocking function and fault isolation discussed above.

SM 750 with FB-SM offers several advantages over HB-SM. For example, FB-SM provides the flexibility to achieve a truly variable DC link voltage. That is, in a typical AC-DC converter, the DC side usually has a higher voltage level than the AC side. In general, the relationship between the phase voltage to neutral on the AC side (V _phase ) and the DC link voltage on the DC side (V _DCLink /2 for HMMC) is a function of √2. More specifically, V _DCLink ≥ 2√2(V _Phase ).

Implementing the SM 750 as a full bridge therefore provides a significant range of features on the DC side, including bi-directional blocking (i.e., the ability to isolate the DC side from the AC side via the SM 750). For example, if a short circuit occurs on the DC side, a shutdown is required to prevent the short circuit on the DC side from interrupting the AC side.

Various embodiments of the present disclosure enable truly variable DC link voltage levels, especially lower than the voltage on the AC side. Various embodiments include: using FB-SMs made of Si IGBTs or SiC MOSFETs; providing a bi-directional blocking IGBT; Replacing only some percentage of SMs compared to conventional MMCs, but with the same or better power quality; To provide embedded isolation protection on the AC side in case of DC link short circuit; and reducing volume, lowering weight, and reducing cost while having equivalent or better power quality performance compared to existing MMCs.

For applications where the DC link voltage is variable and must be lower than the AC input voltage, for example an active front end (AFE) converter interfacing with an AC motor drive/inverter, prior art MMCs will not work. Such applications are included in various embodiments of the present disclosure.

Additionally, embodiments may reduce volume and weight by about 30% or more, semiconductor losses by about 30%, SM capacitor cost by about 50%, and IGBT cost by 25%. These numbers and similar numbers below are approximate estimates only and are not intended to represent any particular limitation or limitation of the embodiments. At the same time, embodiments may maintain the same or improved power quality performance compared to existing MMC technologies.

In addition, HMMCs constructed according to the embodiments provide several distinct advantages over prior art approaches, including:

(a) a variable DC link voltage above or below the AC input voltage;

(b) the number of SMs is reduced by half, while the size and weight are reduced, and the cost is reduced;

(c) high power quality equivalent to conventional MMC with twice the number of SMs;

(d) the same or similar number of conversion levels as conventional MMCs but half the number of SMs and equal or better power quality;

(e) half of the DC link voltage for the SM (0.5 Vdc) allows the use of lower rated devices and modules; 2.5kV, 3.3kV or 4.5kV Si IGBT or SiC MOSFET; Combined MMC Benefits;

(f) only a pair of blocking IGBTs and diodes are shown, more (n switches) can be added if needed (eg xn);

(g) Total volume reduction of 32.5% (25% due to 50% of SM capacitors (which is ~50% of total SM volume), i.e. 25%=50%*50%, and IGBTs which are approximately 50% of SM volume and 12.5% due to 25% of 50% of the gate driver, i.e. 12.5%=25%*50%);

(h) 50% cost reduction of SM capacitor cost, 25% cost reduction of IGBT cost, compared with conventional MMC using full bridge SM;

(i) reduced semiconductor conduction losses (~30%) and improved efficiency due to fewer SMs;

(j) Reduced capacitance for the DC link capacitor (capacitor size). serves only as a communication capacitor;

(k) IGBTs that switch more efficiently, more reliably, with less losses, at lower line frequencies (50 Hz or 60 Hz);

(l) Potential elimination of snubber caps for IGBTs after low (default AC) frequency switching;

(m) Stacking more IGBTs for higher voltages is not a problem, more scalable for higher voltage applications; and

(n) DC to AC isolation in case of DC short fault - static switch due to FB-SM.

Various embodiments have a FB-SM IGBT and one or more same polarity IGBTs in series; have a FB-SM MOSFET and one or more same-polarity IGBTs in series; FB-SM IGBTs and one or more same-polarity MOSFETs in series; have a FB-SM MOSFET and one or more same polarity MOSFETs in series; have a FB-SM IGBT and a bi-directional blocking IGBT; have a FB-SM MOSFET and a bi-directional blocking IGBT; with HFB-SM diodes and Si IGBTs and bi-directional blocking IGBTs; with HFB-SM (diode and SiC MOSFET) and bi-directional blocking IGBT; with HB-SM (diode and Si IGBT) and bi-directional blocking IGBT; or an HMMC based on one or more characteristics including one built on a 3-level NPP topology with HB-SM (diode and SiC MOSFET) and bi-directional blocking IGBT.

Embodiments also have HB-SM (diode and SiC MOSFET) and bidirectional blocking MOSFET; with HB-SM (diode and Si IGBT) and bi-directional blocking MOSFET; have FB-SM IGBTs and bi-directional blocking IGBTs with neutral point pilot switches of Si IGBTs; have FB-SM IGBTs and bi-directional blocking IGBTs with neutral point pilot switches on SiC MOSFETs; have a FB-SM MOSFET and bi-directional blocking IGBT with neutral point pilot switch of Si IGBT; Alternatively, it can include an HMMC based on 3L-NPP with an FB-SM MOSFET and bi-directional blocking IGBT with neutral point pilot switch of SiC MOSFET.

The description herein is provided to enable any person skilled in the art to make or use the present disclosure. Various modifications to this disclosure will be apparent to those skilled in the art, and the general principles defined herein may be applied to other variations without departing from the scope of this disclosure. Accordingly, the present disclosure is not to be limited to the examples and designs described herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims (20)

In a hybrid modular multilevel converter (HMMC) based on a neutral point pilot (NPP) topology and having an ABC N-phase structure,
A hybrid modular multilevel converter (HMMC) comprising N pairs of identical upper and lower arms, each upper and lower arm being composed of X submodules and Y switch sets. According to claim 1,
A hybrid modular multi-level converter (HMMC), wherein the switches in each set are cascaded and connected in series. According to claim 2,
Each of the submodules is formed of a full bridge silicon (Si) insulated-gate bipolar transistor (IGBT) converter;
At least one of the set of switches is formed of an IGBT of opposite polarity, a hybrid modular multi-level converter (HMMC). According to claim 2,
Each of the submodules is formed of a half bridge silicon (Si) insulated gate bipolar transistor (IGBT) converter;
The hybrid modular multi-level converter (HMMC), wherein the switches in each of the Y switch sets are formed of IGBTs of opposite polarity. According to claim 2,
positive and negative direct current (DC) voltage rails, a neutral point node, and (i) N AC terminals forming an AC side and (ii) connected respectively to the upper and lower arms of the N pairs;
wherein the upper arm is connected between the positive DC voltage rail and the neutral point node, and the lower arm is connected between the negative DC voltage rail and the neutral point node. According to claim 5,
The positive and negative DC voltage rails each form respective terminals on the DC side of the HMMC;
Wherein the X submodules are configured to isolate the DC side from the AC side. According to claim 6,
A hybrid modular multi-level converter (HMMC), wherein the voltage value of the phase to neutral may be lower or higher than the DC link voltage value. In a hybrid modular multi-level converter (HMMC) based on a neutral point pilot (NPP) topology,
positive and negative direct current (DC) voltage rails, a neutral point node, and a plurality of phase legs, each of the plurality of phase legs (i) corresponding to an alternating current (AC) phase and (ii) including an upper arm and a lower arm wherein each upper arm is connected between the positive DC voltage rail and the neutral point node, and each lower arm is connected between the negative DC voltage rail and the neutral point node;
At least one of the upper arm and the lower arm:
two or more series-connected submodules having a first lead connected at least indirectly to the positive DC voltage rail and a second lead connected to an output terminal of the corresponding AC phase; and
A first set of cascaded switches connected in series, wherein (i) one end is connected to the output terminal and (ii) the other end is connected to the neutral point node.
A hybrid modular multi-level converter (HMMC) comprising a. According to claim 8,
wherein the output terminal comprises (i) one end configured to be connected to an AC source/input and (ii) the other end connected to its corresponding phase leg. According to claim 9,
and a second set of cascaded switches connected in series between the positive DC voltage rail and the two or more series connected submodules. According to claim 10,
Each of the submodules is formed of a full bridge silicon (Si) insulated gate bipolar transistor (IGBT) converter;
The hybrid modular multi-level converter (HMMC), wherein the first set of cascaded switches is formed of IGBTs of opposite polarity. According to claim 11,
wherein the first set of cascaded switches are bi-directional blocking IGBTs. According to claim 12,
The hybrid modular multi-level converter (HMMC), wherein the first set of cascaded switches is formed of free-wheeling diodes. According to claim 13,
A first capacitor having one end coupled to the positive DC voltage rail and the other end coupled to the neutral point node, and a first capacitor having one end coupled to the negative DC voltage rail and the other end coupled to the neutral point node. A hybrid modular multi-level converter (HMMC), further comprising 2 capacitors. According to claim 10,
Each of the submodules is formed of a full bridge silicon carbide (SiC) metal oxide semiconductor field effect transistor (MOSFET) converter;
The hybrid modular multi-level converter (HMMC), wherein the first and second sets of cascaded switches are formed of opposite polarity diodes and SiC MOSFETs. According to claim 8,
The hybrid modular multi-level converter (HMMC), wherein the diode is freewheeling. According to claim 10,
Each of the submodules is formed of a half-bridge Si IGBT converter,
The hybrid modular multi-level converter (HMMC), wherein the first and second sets of cascaded switches are formed of opposite polarity diodes and SiC MOSFETs. According to claim 10,
The hybrid modular multi-level converter (HMMC), wherein the diode is freewheeling. According to claim 8,
A hybrid modular multi-level converter (HMMC), wherein the line-to-line voltage value may be lower or higher than the DC link voltage value. In a hybrid modular multi-level converter (HMMC) based on a neutral point pilot (NPP) topology and having an ABC N-phase structure,
N pairs of identical upper and lower arms, each upper and lower arm composed of X submodules and Y switch sets;
The switches in each set are cascaded and connected in series,
Each of the submodules is formed of a full bridge silicon (Si) insulated gate bipolar transistor (IGBT) converter;
At least one of the set of switches is formed of an IGBT of opposite polarity, a hybrid modular multi-level converter (HMMC).

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