Three-level converter and driving circuit thereof

Abstract

The embodiment of the invention discloses a three-level converter and a driving circuit thereof, and relates to the technical field of power electronics, the driving circuit comprises a multi-phase driving circuit, and any phase driving circuit comprises a first driving switch, a second driving switch, a third driving switch, a fourth driving switch and a plurality of antiparallel diodes; the midpoint of the bridge arm is connected with an AC side, connected with a DC bus positive pole through a first driving switch, connected with a DC bus midpoint through a second driving switch and a third driving switch which are connected in series, and connected with a DC bus negative pole through a fourth driving switch, and the DC bus is connected with a DC load or a power supply; each driving switch is connected with an anti-parallel diode in parallel, and the second driving switch and the third driving switch are connected through a common drain electrode or a common collector electrode. Through the mode, the isolation driving power supply can be reasonably distributed, the cost is saved, and the efficiency of the driving circuit is improved.

Description

Technical Field

[0001] The embodiments of the present invention relate to the field of power electronics technology, and in particular to a three-level converter and a driving circuit thereof. Background Art

[0002] The existing power converter uses two power switch tubes in series in the bridge arm from the midpoint of each phase bridge arm to the midpoint of the DC bus. Each power switch tube adopts a common source or common emitter layout. This layout requires at least five, seven, nine, or eleven isolated power supplies for two-phase, three-phase, four-phase, and five-phase topologies. Figure 1 The two-phase common source layout and Figure 2 The three-phase common source layout is adopted, and each power switch tube adopts a common source or common emitter layout. The power switch tubes Va2 and Va3 of phase a use the same isolated driving power supply, and the power switch tubes Va2 and Va3 of different phases use different isolated driving power supplies.

[0003] It can be seen that when using the common source layout, it is necessary to set an isolated driving power supply for each bridge arm from the midpoint of each phase bridge arm to the midpoint of the DC bus. For the N-phase T-neutral point clamped (NPC) topology, a total of 2N+1 isolated driving power supplies are required, and for the N-phase half-bridge topology, a total of N+1 isolated driving power supplies are required. Therefore, when using the common source layout, the N-phase T-NPC topology adds N isolated driving power supplies compared to the N-phase half-bridge topology, which increases the cost of converting the N-phase half-bridge to the N-phase T-NPC. Summary of the invention

[0004] In view of the above problems, an embodiment of the present invention provides a three-level converter and a driving circuit thereof, which overcomes the above problems or at least partially solves the above problems.

[0005] According to one aspect of an embodiment of the present invention, a driving circuit of a three-level converter is provided, comprising: a multi-phase driving circuit, wherein any phase driving circuit comprises: a first driving switch, a second driving switch, a third driving switch, a fourth driving switch and a plurality of anti-parallel diodes; a bridge arm midpoint of any phase is connected to an AC side, wherein the AC side is used to provide a phase voltage or a load, wherein the bridge arm midpoint is connected to a positive pole of a DC bus through the first driving switch, is connected to a DC bus midpoint through the second driving switch and the third driving switch connected in series, and is also connected to a negative pole of the DC bus through the fourth driving switch, wherein the DC bus is connected to a DC load or a power supply; wherein the first driving switch, the second driving switch, the third driving switch and the fourth driving switch are respectively connected in parallel with an anti-parallel diode, and the second driving switch and the third driving switch are connected in common drain or collector.

[0006] Optionally, the first drive switch, the second drive switch, the third drive switch and the fourth drive switch are MOSFETs, and the second drive switch and the third drive switch are connected with a common drain.

[0007] Optionally, the midpoint of the bridge arm is connected to the source of the second drive switch, the drain of the second drive switch is connected to the drain of the third drive switch, the source of the third drive switch is connected to the midpoint of the DC bus, and the anti-parallel diodes are respectively connected between the drain and source of the second drive switch and between the drain and source of the third drive switch.

[0008] Optionally, the first drive switch, the second drive switch, the third drive switch and the fourth drive switch are IGBTs, and the second drive switch and the third drive switch are connected with a common collector.

[0009] Optionally, the midpoint of the bridge arm is connected to the emitter of the second drive switch, the collector of the second drive switch is connected to the emitter of the third drive switch, the emitter of the third drive switch is connected to the midpoint of the DC bus, and the anti-parallel diodes are respectively connected between the collector and the emitter of the second drive switch and between the collector and the emitter of the third drive switch.

[0010] Optionally, the first drive switch and the second drive switch in the same phase drive circuit use the same isolated drive power supply, and the first drive switch, the third drive switch and the fourth drive switch are driven by different isolated drive power supplies.

[0011] Optionally, the drive circuit includes: a two-phase, three-phase, four-phase or five-phase drive circuit.

[0012] Optionally, if the drive circuit includes N-phase drive circuits, N+2 isolated drive power supplies are used to drive the first drive switch, the second drive switch, the third drive switch and the fourth drive switch in each phase drive circuit.

[0013] Optionally, the first drive switches in different phase drive circuits are driven by different isolated drive power supplies, the third drive switches in different phase drive circuits are driven by the same isolated drive power supply, and the fourth drive switches in different phase drive circuits are driven by the same isolated drive power supply.

[0014] Based on the same inventive concept, a three-level converter is provided, comprising: the aforementioned driving circuit of the three-level converter.

[0015] The driving circuit of the three-level converter of the embodiment of the present invention comprises: a multi-phase driving circuit, wherein any phase driving circuit comprises: a first driving switch, a second driving switch, a third driving switch, a fourth driving switch and a plurality of anti-parallel diodes; a bridge arm midpoint of any phase is connected to an AC side, wherein the AC side is used to provide a phase voltage or a load, wherein the bridge arm midpoint is connected to a DC bus positive pole through the first driving switch, is connected to a DC bus midpoint through the second driving switch and the third driving switch connected in series, and is also connected to a DC bus negative pole through the fourth driving switch, wherein the DC bus is connected to a DC load or a power supply; wherein the first driving switch, the second driving switch, the third driving switch and the fourth driving switch are respectively connected in parallel with an anti-parallel diode, wherein the second driving switch and the third driving switch are connected in common drain or common collector, wherein the second driving switch and the third driving switch are adjusted to be in a common drain layout mode, and an isolated driving power supply is reasonably distributed, so that the number of required isolated driving power supplies is reduced from 2N+1 to N+2, thereby saving costs and improving the efficiency of the driving circuit.

[0016] The above description is only an overview of the technical solution of the embodiment of the present invention. In order to more clearly understand the technical means of the embodiment of the present invention, it can be implemented in accordance with the contents of the specification. In order to make the above and other purposes, features and advantages of the embodiment of the present invention more obvious and easy to understand, the specific implementation methods of the present invention are listed below. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Various other advantages and benefits will become apparent to those of ordinary skill in the art by reading the detailed description of the preferred embodiments below. The accompanying drawings are only for the purpose of illustrating the preferred embodiments and are not to be considered as limiting the present invention. Moreover, the same reference symbols are used throughout the accompanying drawings to represent the same components. In the accompanying drawings:

[0018] Figure 1 A schematic diagram of a two-phase T-NPC common source layout in the prior art is shown;

[0019] Figure 2 A schematic diagram of a three-phase T-NPC common source layout is shown;

[0020] Figure 3 A schematic structural diagram of a driving circuit of a three-level converter according to an embodiment of the present invention is shown;

[0021] Figure 4 An exemplary diagram showing a driving circuit of a two-phase three-level converter according to an embodiment of the present invention is shown;

[0022] Figure 5 A schematic structural diagram of a driving circuit of a T-type three-phase three-level converter according to an embodiment of the present invention is shown;

[0023] Figure 6 An exemplary diagram showing a driving circuit of a T-type three-phase three-level converter according to an embodiment of the present invention is shown;

[0024] Figure 7 The structure diagram of the driving circuit of the non-isolated SWISS three-level converter according to the embodiment of the present invention is shown. DETAILED DESCRIPTION

[0025] The exemplary embodiments of the present invention will be described in more detail below with reference to the accompanying drawings. Although the exemplary embodiments of the present invention are shown in the accompanying drawings, it should be understood that the present invention can be implemented in various forms and should not be limited by the embodiments set forth herein. On the contrary, these embodiments are provided in order to enable a more thorough understanding of the present invention and to enable the scope of the present invention to be fully communicated to those skilled in the art.

[0026] Figure 3 FIG. 1 shows a schematic diagram of a structure of a driving circuit of a three-level converter provided by an embodiment of the present invention. Figure 3 As shown, the driving circuit of the three-level converter includes: a multi-phase driving circuit, and any phase driving circuit includes: a first driving switch Va1 / Vb1, a second driving switch Va2 / Vb2, a third driving switch Va3 / Vb3, a fourth driving switch Va4 / Vb4 and a plurality of anti-parallel diodes Da1 / Db1 / Da2 / Db2 / Da3 / Db3 / Da4 / Db4. The bridge arm midpoint a / b of any phase is connected to the AC side, and the AC side is used to provide phase voltage or load. The bridge arm midpoint a / b is connected to the DC bus positive pole p through the first driving switch Va1 / Vb1, connected to the DC bus midpoint o through the second driving switch Va2 / Vb2 and the third driving switch Va3 / Vb3 connected in series, and connected to the DC bus negative pole n through the fourth driving switch Va4 / Vb4. The DC bus is connected to a DC load or power supply, and includes necessary filter capacitors. The load or power supply may be composed of other level circuits. The first drive switch, the second drive switch, the third drive switch and the fourth drive switch are respectively connected in parallel with an anti-parallel diode. The second drive switch and the third drive switch are connected in common drain or common collector.

[0027] The AC side includes the phase voltage supply e a / e b / e c and the first inductor L a / L b / L c The midpoint of the bridge arm of any phase passes through the first inductor L a / L b / L cThe DC bus includes a first capacitor C1, a second capacitor C2 and a load resistor RL between the DC bus positive pole p and the negative pole n. The first capacitor C1 is connected between the DC bus midpoint o and the positive pole p. The second capacitor C2 is connected between the DC bus midpoint o and the negative pole n. One end of the load resistor RL is connected to the DC bus positive pole p, and the other end is connected to the DC bus negative pole n. For more details, see Figure 4 ,for Figure 4 In the a-phase driving circuit, the bridge arm midpoint a passes through the first inductor L a Connect to a phase voltage power supply e a , the midpoint a of the bridge arm is connected to the positive pole p of the DC bus through the first drive switch Va1, connected to the bus midpoint o through the second drive switch Va2 and the third drive switch Va3 connected in series, and connected to the negative pole n of the DC bus through the fourth drive switch Va4. An anti-parallel diode Da1 is connected in parallel between the drain and source of the first drive switch Va1, an anti-parallel diode Da2 is connected in parallel between the drain and source of the second drive switch Va2, an anti-parallel diode Da3 is connected in parallel between the drain and source of the third drive switch Va3, and an anti-parallel diode Da4 is connected in parallel between the drain and source of the fourth drive switch Va4. It should be noted that the first drive switch Va1 and the fourth drive switch Va4 can be connected in common source (see Figure 3 and Figure 4 ), or a common drain connection.

[0028] The same is true for Figure 3 and Figure 4 In the b-phase driving circuit, the bridge arm midpoint b passes through the first inductor L b Connect to phase b voltage power supply e b , the bridge arm midpoint b is connected to the DC bus positive pole p through the first drive switch Vb1, connected to the DC bus midpoint o through the second drive switch Vb2 and the third drive switch Vb3 connected in series, and connected to the DC bus negative pole n through the fourth drive switch Vb4. An anti-parallel diode Db1 is connected in parallel between the drain and source of the first drive switch Vb1, an anti-parallel diode Db2 is connected in parallel between the drain and source of the second drive switch Vb2, an anti-parallel diode Db3 is connected in parallel between the drain and source of the third drive switch Vb3, and an anti-parallel diode Db4 is connected in parallel between the drain and source of the fourth drive switch Vb4. It should be noted that the first drive switch Vb1 and the fourth drive switch Vb4 can be connected in common source (see Figure 3 and Figure 4 ), or a common drain connection.

[0029] In the embodiments of this application, see Figure 3 and Figure 4, the first drive switch Va1 / Vb1, the second drive switch Va2 / Vb2, the third drive switch Va3 / Vb3 and the fourth drive switch Va4 / Vb4 are MOSFETs, and the second drive switch Va2 / Vb2 and the third drive switch Va3 / Vb3 are connected with a common drain. At this time, the bridge arm midpoint a / b is connected to the source of the second drive switch Va2 / Vb2, the drain of the second drive switch Va2 / Vb2 is connected to the drain of the third drive switch Va3 / Vb3, the source of the third drive switch Va3 / Vb3 is connected to the DC bus midpoint o, and anti-parallel diodes are connected between the drain and source of the second drive switch Va2 / Vb2 and between the drain and source of the third drive switch Va3 / Vb3.

[0030] The first drive switch, the second drive switch, the third drive switch and the fourth drive switch may also be IGBTs, and the second drive switch and the third drive switch are connected with a common collector. In this way, the midpoint of the bridge arm is connected to the emitter of the second drive switch, the collector of the second drive switch is connected to the emitter of the third drive switch, the emitter of the third drive switch is connected to the midpoint o of the DC bus, and anti-parallel diodes are connected between the collector and the emitter of the second drive switch and between the collector and the emitter of the third drive switch.

[0031] In the embodiment of the present application, the first drive switch and the second drive switch of the same drive circuit use the same isolated drive power supply, and the first drive switch, the third drive switch and the fourth drive switch are driven by different isolated drive power supplies. Figure 3 and Figure 4 , the first drive switch Va1 and the second drive switch Va2 in the a-phase drive circuit use isolated drive power supply 1, the first drive switch Va1 in the a-phase drive circuit uses isolated drive power supply 1, the third drive switch Va3 uses isolated drive power supply 3, and the fourth drive switch Va4 uses isolated drive power supply 4, and the three isolated drive power supplies are different. The first drive switch Vb1 and the second drive switch Vb2 in the b-phase drive circuit use isolated drive power supply 2. The first drive switch Vb1 in the b-phase drive circuit uses isolated drive power supply 2, the third drive switch Vb3 uses isolated drive power supply 3, and the fourth drive switch Vb4 uses isolated drive power supply 4, and the three isolated drive power supplies are different.

[0032] The first drive switches in the different phase drive circuits are driven by different isolated drive power supplies, the third drive switches in the different phase drive circuits are driven by the same isolated drive power supply, and the fourth drive switches in the different phase drive circuits are driven by the same isolated drive power supply. Figure 3 and Figure 4In the embodiment, the first drive switch Va1 in the a-phase drive circuit uses an isolated drive power supply 1, and the first drive switch Vb1 in the b-phase drive circuit uses an isolated drive power supply 2. The third drive switch Va3 in the a-phase drive circuit and the third drive switch Vb3 in the b-phase drive circuit both use an isolated drive power supply 3. The fourth drive switch Va4 in the a-phase drive circuit and the fourth drive switch Vb4 in the b-phase drive circuit both use an isolated drive power supply 4.

[0033] Optionally, the drive circuit includes: a two-phase, three-phase, four-phase or five-phase drive circuit. If the drive circuit includes an N-phase drive circuit, N+2 isolated drive power supplies are used to drive the first drive switch, the second drive switch, the third drive switch and the fourth drive switch in each phase drive circuit. Figure 3 and Figure 4 In the embodiment, the driving circuit includes a two-phase driving circuit, and four isolated driving power supplies are used to drive a first driving switch Va1 / Vb1, a second driving switch Va2 / Vb2, a third driving switch Va3 / Vb3 and a fourth driving switch Va4 / Vb4. Figure 5 and Figure 6 In the embodiment, the driving circuit includes a three-phase driving circuit, and five isolated driving power supplies are used to drive the first driving switch Va1 / Vb1 / Vc1, the second driving switch Va2 / Vb2 / Vc2, the third driving switch Va3 / Vb3 / Vc3 and the fourth driving switch Va4 / Vb4 / Vc4. Figure 5 and Figure 6 A driving circuit of a three-phase three-level converter including a three-phase driving circuit and Figure 3 and Figure 4 The driving circuit structure of the two-phase three-level converter including the two-phase driving circuit is similar and will not be described in detail here.

[0034] Figure 3-Figure 6 The driving circuit of the three-level converter in the embodiment of the present application may also be a driving circuit of a non-isolated SWISS type AC / DC three-level converter. Figure 7 The driving circuit of the three-phase non-isolated SWISS type AC / DC converter is Figure 6The driving circuit of the three-phase T-type three-level converter in is similar, and the only difference is that the DC side connected to the DC bus includes a first switch tube V1, a second switch tube V2, a third switch tube V3, a fourth switch tube V4, a second inductor Ldc, a third capacitor C3 and a load resistor RL. The drain of the first switch tube V1 is connected to the positive pole p of the DC bus, the source of the second switch tube V2 is connected to the first end of the second inductor and the drain of the third switch tube V3, the source of the third switch tube V3 and the drain of the fourth switch tube V4 are connected to the midpoint o of the DC bus, the source of the second switch tube V2 is connected to the negative pole n of the DC bus, the drain of the second switch tube V2 is connected to the source of the fourth switch tube V4, and the third capacitor C3 and the load resistor RL are connected in parallel with each other and connected between the second end of the second inductor Ldc and the drain of the second switch tube V2.

[0035] In the driving circuit of the three-level converter in the embodiment of the present application, the bridge arm from the midpoint of each phase bridge arm to the midpoint of the DC bus adopts a common drain layout, and there is no need to set up an isolated driving power supply for each bridge arm from the midpoint of each phase bridge arm to the midpoint of the DC bus. For each phase, a MOSFET in the bridge arm can share a power supply with the upper tube, and another MOSFET in each phase can share an isolated driving power supply. For the N-phase topology, a total of N+2 isolated driving power supplies are required. Therefore, when using the common drain layout, the N-phase T-NPC topology only adds 1 isolated driving power supply compared to the N-phase half-bridge topology, and reduces N-1 independent power supplies compared to the common source layout, effectively reducing the transformation cost.

[0036] In summary, the driving circuit of the three-level converter of the embodiment of the present application includes: a multi-phase driving circuit, any phase driving circuit includes: a first driving switch, a second driving switch, a third driving switch, a fourth driving switch and a plurality of anti-parallel diodes; the midpoint of the bridge arm of any phase is connected to the AC side, the AC side is used to provide a phase voltage or a load, the midpoint of the bridge arm is connected to the positive pole of the DC bus through the first driving switch, is connected to the midpoint of the DC bus through the second driving switch and the third driving switch connected in series, and is also connected to the negative pole of the DC bus through the fourth driving switch, and the DC bus is connected to the DC load or power supply; the first driving switch, the second driving switch, the third driving switch and the fourth driving switch are respectively connected in parallel with an anti-parallel diode, the second driving switch and the third driving switch are connected in common drain or common collector, and the driving power supply is reasonably distributed by adjusting the second driving switch and the third driving switch to a common drain layout mode, so that the number of required isolated driving power supplies is reduced from 2N+1 to N+2, which can save costs and improve the efficiency of the driving circuit.

[0037] Based on the same concept, an embodiment of the present invention further provides a T-type three-level converter, which includes the aforementioned driving circuit of the T-type three-level converter.

[0038] The above specific embodiments of the present invention are described. In some cases, the actions or steps recorded in the embodiments of the present invention can be performed in an order different from that in the embodiments and still achieve the desired results. In addition, the process depicted in the accompanying drawings does not necessarily require the specific order or continuous order shown to achieve the desired results. In some embodiments, multitasking and parallel processing are also possible or may be advantageous.

[0039] The method of the above embodiment is applied to the corresponding current loop structure in the above embodiment, and has the beneficial effects of the corresponding current loop structure embodiment, which will not be described in detail here.

[0040] Those skilled in the art should understand that the discussion of any of the above embodiments is merely illustrative and is not intended to imply that the scope of the present disclosure is limited to these examples. Based on the concept of the present disclosure, the technical features in the above embodiments or different embodiments may be combined, the steps may be implemented in any order, and there are many other variations of the different aspects of the embodiments of the present invention as described above, which are not provided in detail for the sake of simplicity.

[0041] This application is intended to cover all such substitutions, modifications and variations that fall within the broad scope of all embodiments. Therefore, any omissions, modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the embodiments of the present invention should be included in the scope of protection of this disclosure.

Claims

1. A driving circuit for a three-level converter, characterized in that: The drive circuit includes: a multi-phase drive circuit, any phase drive circuit includes: a first drive switch, a second drive switch, a third drive switch, a fourth drive switch and a plurality of anti-parallel diodes; the midpoint of a bridge arm of any phase is connected to an AC side, the AC side is used to provide a phase voltage or a load, the midpoint of the bridge arm is connected to a positive pole of a DC bus through the first drive switch, is connected to a midpoint of a DC bus through the second drive switch and the third drive switch connected in series, and is also connected to a negative pole of a DC bus through the fourth drive switch, and the DC bus is connected to a DC load or a power supply; the first drive switch, the second drive switch, the third drive switch and the fourth drive switch are respectively connected in parallel with an anti-parallel diode, and the second drive switch and the third drive switch are connected in common drain or collector.

2. The driving circuit according to claim 1, characterized in that: The first drive switch, the second drive switch, the third drive switch and the fourth drive switch are MOSFETs, and the second drive switch and the third drive switch are connected with a common drain.

3. The driving circuit according to claim 2, characterized in that: The midpoint of the bridge arm is connected to the source of the second drive switch, the drain of the second drive switch is connected to the drain of the third drive switch, the source of the third drive switch is connected to the midpoint of the DC bus, and the anti-parallel diodes are respectively connected between the drain and source of the second drive switch and between the drain and source of the third drive switch.

4. The driving circuit according to claim 1, characterized in that: The first drive switch, the second drive switch, the third drive switch and the fourth drive switch are IGBTs, and the second drive switch and the third drive switch are connected using a common collector.

5. The driving circuit according to claim 4, characterized in that: The midpoint of the bridge arm is connected to the emitter of the second drive switch, the collector of the second drive switch is connected to the emitter of the third drive switch, the emitter of the third drive switch is connected to the midpoint of the DC bus, and the anti-parallel diodes are respectively connected between the collector and the emitter of the second drive switch and between the collector and the emitter of the third drive switch.

6. The driving circuit according to claim 1, characterized in that: The first drive switch and the second drive switch in the same phase drive circuit use the same isolated drive power supply, and the first drive switch, the third drive switch and the fourth drive switch are driven by different isolated drive power supplies.

7. The driving circuit according to claim 1, characterized in that: The driving circuit includes: a two-phase, three-phase, four-phase or five-phase driving circuit.

8. The driving circuit according to claim 7, characterized in that: If the driving circuit includes N-phase driving circuits, N+2 isolated driving power supplies are used to drive the first driving switch, the second driving switch, the third driving switch and the fourth driving switch in each phase driving circuit.

9. The driving circuit according to claim 8, characterized in that: The first drive switches in different phase drive circuits are driven by different isolated drive power supplies, the third drive switches in different phase drive circuits are driven by the same isolated drive power supply, and the fourth drive switches in different phase drive circuits are driven by the same isolated drive power supply.

10. A three-level converter, characterized in that: The three-level converter includes the driving circuit of the three-level converter according to any one of claims 1 to 9.

Images