CN103368427A - Single-phase inverter and system thereof and three-phase inverter and system thereof - Google Patents

Abstract

The invention relates to a single-phase inverter and its system and a three-phase inverter and its system. A single-phase inverter, comprising: a first single-phase inverter circuit and a second single-phase inverter circuit configured to be connected in parallel to both ends of the DC source and having the same structure; a drive circuit configured to drive the first single-phase inverter circuit with a first drive signal A single-phase inverter circuit drives the second single-phase inverter circuit with a second drive signal, the first drive signal is modulated by the first modulation wave and the first carrier wave, and the second drive signal is modulated by the second modulation wave and the second Carrier modulation, the first modulation wave and the second modulation wave have the same phase; and the first coupling inductor and the second coupling inductor, the input end of the first coupling inductor receives the current output by the first single-phase inverter circuit , the input terminal of the second coupled inductor receives the current output from the second single-phase inverter circuit, and the first coupled inductor and the second coupled inductor are reversely coupled and their output terminals are connected together.

Description

Single-phase inverter and its system and three-phase inverter and its system

technical field

The invention relates to an inverter, in particular to a single-phase inverter and its system, a three-phase inverter and its system.

Background technique

The inverter plays the role of converting direct current into alternating current. Inverters are an important part of power generation systems. Efficiency is one of the most important performance indicators of an inverter. If the efficiency is improved, it can bring considerable economic benefits.

The loss of power devices and output filter inductors in the inverter limits the improvement of inverter efficiency. At the same time, fierce market competition and rising prices of raw materials such as steel and copper have brought great cost pressure to inverter manufacturers. At present, due to the limitation of the performance of power devices, it is difficult to reduce the loss of power devices and filter inductors in traditional inverter topologies. In addition, the filter inductor is bulky and expensive. Therefore, the development of high-performance and low-cost inverters has become the goal of various inverter manufacturers.

In the traditional 2-level topology inverter, after the power switching device is turned on, the tube voltage drop is large, and the on-state loss and switching loss are very large, resulting in a large total loss of the power switching device, thereby reducing the efficiency of the entire system.

Neutral point clamped (NPC) topology results in large total loss and low efficiency due to the large number of power switching devices and the addition of clamping diodes.

Therefore, it is desirable to provide an inverter capable of reducing losses of power switching devices and reducing losses and costs of inductors.

Contents of the invention

A brief overview of the invention is given below in order to provide a basic understanding of some aspects of the invention. It should be understood that this summary is not an exhaustive overview of the invention. It is not intended to identify key or critical parts of the invention nor to delineate the scope of the invention. Its purpose is merely to present some concepts in a simplified form as a prelude to the more detailed description that is discussed later.

A main object of the present invention is to provide a single-phase inverter and its system and a three-phase inverter and its system.

According to one aspect of the present invention, a single-phase inverter is provided, including: a first single-phase inverter circuit and a second single-phase inverter circuit configured to be connected in parallel to both ends of a DC source and have the same structure; a drive circuit , configured to drive the first single-phase inverter circuit with a first drive signal and drive the second single-phase inverter circuit with a second drive signal, the first drive signal being modulated by a first modulation wave and a first carrier wave Formed, the second drive signal is modulated by the second modulation wave and the second carrier wave, the phase of the first modulation wave and the second modulation wave is the same; and the first coupling inductor and the second coupling inductor The input end of the first coupled inductor receives the current output by the first single-phase inverter circuit, the input end of the second coupled inductor receives the current output by the second single-phase inverter circuit, And the first coupled inductor and the second coupled inductor are reversely coupled and their output terminals are connected together.

According to another aspect of the present invention, a single-phase inverter system is provided, including K single-phase inverters as described above, K is an integer greater than or equal to 1, wherein K of the first coupled inductor and the output terminals of the K second coupled inductors are connected together.

According to yet another aspect of the present invention, a three-phase inverter is provided, including: a first three-phase inverter circuit and a second three-phase inverter circuit configured to be connected in parallel to both ends of a DC source and have the same structure, wherein , the first three-phase inverter circuit includes a first A-phase inverter circuit, a first B-phase inverter circuit and a first C-phase inverter circuit, and the second three-phase inverter circuit includes a second A-phase inverter circuit inverter circuit, a second B-phase inverter circuit, and a second C-phase inverter circuit; a drive circuit configured to drive the first A-phase drive signal, the first B-phase drive signal, and the first C-phase drive signal respectively. The first A-phase inverter circuit, the first B-phase inverter circuit and the first C-phase inverter circuit are driven by the second A-phase drive signal, the second B-phase drive signal and the second C-phase drive signal respectively The signal drives the second A-phase inverter circuit, the second B-phase inverter circuit, and the second C-phase inverter circuit, and modulates the first A-phase modulation wave used by the first A-phase drive signal with the The phase of the second A-phase modulating wave used for modulating the second A-phase driving signal is the same, and the first B-phase modulating wave used for modulating the first B-phase driving signal is the same as that used for modulating the second B-phase driving signal. The phase of the second B-phase modulation wave is the same, and the phase of the first C-phase modulation wave used to modulate the first C-phase drive signal is the same as that of the second C-phase modulation wave used to modulate the second C-phase drive signal; including The A-phase filter circuit of the first A-phase coupled inductor and the second A-phase coupled inductor; the B-phase filter circuit including the first B-phase coupled inductor and the second B-phase coupled inductor; including the first C-phase coupled inductor Inverter and the C-phase filter circuit of the second C-phase coupled inductor; wherein, the input terminals of the coupled inductor respectively receive the first A-phase inverter circuit, the second A-phase inverter circuit, and the first A-phase inverter circuit. Corresponding output currents of a B-phase inverter circuit, the second B-phase inverter circuit, the first C-phase inverter circuit, and the second C-phase inverter circuit, the first A-phase coupled inductor reversely coupled with the second A-phase coupled inductor and its output terminals are connected together, and the first B-phase coupled inductor and the second B-phase coupled inductor are reversely coupled and their output terminals are connected together , the first C-phase coupled inductor and the second C-phase coupled inductor are anti-phase coupled and their output terminals are connected together.

According to still another aspect of the present invention, a three-phase inverter system is provided, including: K three-phase inverters as described above, K is an integer greater than or equal to 1, wherein, the K first A The phase coupled inductors are connected to the output ends of the K second A-phase coupled inductors, and the K first B-phase coupled inductors are connected to the output ends of the K second B-phase coupled inductors. together, and the output terminals of the K first C-phase coupled inductors and the K second C-phase coupled inductors are connected together.

Description of drawings

The above and other objects, features and advantages of the present invention will be more easily understood with reference to the following description of the embodiments of the present invention in conjunction with the accompanying drawings. The components in the drawings are only to illustrate the principles of the invention. In the drawings, the same or similar technical features or components will be denoted by the same or similar reference numerals.

FIG. 1A is a diagram illustrating a single-phase inverter based on a three-level T-type topology according to an embodiment of the present invention;

FIG. 1B is a waveform diagram showing a carrier wave, a modulating wave, a driving signal and a voltage for the first three-level T-type topology T101 of FIG. 1A;

2 is a diagram illustrating a single-phase inverter based on a three-level NPC topology according to an embodiment of the present invention;

FIG. 3 is a diagram illustrating a single-phase inverter system composed of multiple topologies according to an embodiment of the present invention;

4A to 4C are diagrams illustrating various examples of filter circuits according to embodiments of the present invention;

5 is a diagram illustrating a three-phase inverter according to an embodiment of the present invention;

6 is a block diagram illustrating a three-phase inverter system according to an embodiment of the present invention; and

FIG. 7 is a block diagram illustrating a three-phase inverter system according to an embodiment of the present invention.

Detailed ways

Embodiments of the present invention will be described below with reference to the drawings. Elements and features described in one drawing or one embodiment of the present invention may be combined with elements and features shown in one or more other drawings or embodiments. It should be noted that representation and description of components and processes that are not related to the present invention and known to those of ordinary skill in the art are omitted from the drawings and descriptions for the purpose of clarity.

First, a single-phase inverter 100 based on a three-level T-type topology according to an embodiment of the present invention will be described with reference to FIGS. 1A and 1B .

As shown in FIG. 1A, the single-phase inverter 100 includes two three-level T-topologies connected in parallel at both ends of the DC source Udc, that is, the first three-level T-topology T101 and the second three-level T-topology T101' . Specifically, the first three-level T-type topology T101 includes diodes D101, D102, D103 and D104, power switching devices (hereinafter referred to as switches) S101, S102, S103 and S104, and capacitors C101 and C102. The second three-level T-topology T101' comprises diodes D101', D102', D103' and D104', switches S101', S102', S103' and S104', and capacitors C101' and C102'.

The single-phase inverter 100 also includes a first coupled inductor L101 connected to the output terminal P2 of the first three-level T-type topology T101, and a coupled inductor L101 connected to the output terminal P2' of the second three-level T-type topology T101'. The second coupled inductor L101'.

(a) in FIG. 1B shows a waveform diagram of driving signals a1 , a2 , a3 and a4 driving the first three-level T-type topology T101 . Wherein, the driving signal a1 is used to drive the switch S101 , the driving signal a2 is used to drive the switch S102 , the driving signal a3 is used to drive the switch S103 , and the driving signal a4 is used to drive the switch S104 .

(b) in FIG. 1B shows a modulated wave (sine wave) and triangular wave 1 and triangular wave 2 . The modulation wave and the triangular wave 1 modulation generate a driving signal a1 for driving the switch S101 and a driving signal a3 for driving the switch S103. The modulation wave and the triangular wave 2 are adjusted to generate the driving signal a2 for driving the switch S102 and the driving signal a4 for driving the switch S104.

(c) in FIG. 1B shows the voltage waveform output from point P2 driven by the first three-level T-type topology T101 driven by the driving signals a1 , a2 , a3 and a4 .

Although each parameter in FIG. 1B is shown with specific values, it should be understood that these values are only specific examples and not intended to be specific limitations.

As far as the first three-level T-type topology T101 is concerned, when switching between positive level voltage and zero level voltage, the switch S101 operates under the driving signal a1, and the switch S104 is normally turned on under the driving signal a4 . Specifically, when the switch S101 is turned on, the current flows from the DC source Udc through the positive bus BUSP, the switch S101, the point P2, and the first coupled inductor L101, and flows to the load R. At this time, the point P2 is at a positive level Voltage. When the switch S101 is turned off, the current flows from the midpoint P1 through the diode D103, the switch S104, the point P2 and the first coupled inductor L101, and flows to the load R. At this time, the point P2 is a zero-level voltage.

Similarly, when switching between the negative level voltage and the zero level voltage, the switch S102 acts under the driving signal a2, and the switch S103 is normally turned on under the driving signal a3. Specifically, when the switch S102 is turned on, the current flows from the load R through the first coupled inductor L101, the point P2, and the switch S102, and flows to the negative bus BUSN. At this time, the voltage at the point P2 is negative. When the switch S102 is turned off, the current flows from the load R through the first coupling inductor L101, the point, P2, the diode D104 and the switch S103, and flows to the midpoint P1, and the point P2 is at zero level voltage.

The drive signals for the second three-level T-topology T101' are similar to those for the first three-level T-topology T101. The modulation wave used to modulate the driving signal for the second three-level T-type topology T101' and the modulation wave used for modulating the driving signal for the first three-level T-type topology T101 have the same phase. In this way, in the case of reverse coupling of the coupled inductors L201 and L201', the coupled inductors L201 and L201' can completely cancel the magnetic field generated by the current output from point P2 and the fundamental frequency of the current output from point P2'.

The phase of the carrier used to modulate the driving signal for the second three-level T-topology T101' and the carrier used for modulating the driving signal for the first three-level T-topology T101 may differ by 180 degrees. In this way, the coupled inductors L201 and L201' can partly cancel the magnetic field generated by the current output from point P2 and the harmonics of the current output from point P2'.

The second three-level T-type topology T101' has a similar structure to the first three-level T-type topology T101, so the working principles are similar, and will not be repeated here.

The switches on the auxiliary bridge arms of the first three-level T-type topology T101 and the second three-level T-type topology T101', that is, the switches S103, S104, S103' and S104' only bear half of the bus voltage when switching, so The loss is much lower than that of the 2-level topology and the NPC topology, which can improve the working efficiency of the inverter. Thus a three-level T-topology is preferred. However, it can be seen from the later description that the idea of the present invention can also be applied to 2-level topologies, or to other three-level topologies, such as three-level NPC topologies.

In addition, as shown in FIG. 1A , the single-phase inverter 100 may further include an inductor L and a capacitor C. As shown in FIG. In this case, the inductor group formed by the first coupled inductor L101 and the second coupled inductor L101' together with the inductor L and the capacitor C forms an LCL filter circuit for the first three-level T-type topology The current output by T101 and the second three-level T-type topology T101' is filtered.

Optionally, the single-phase inverter 100 may not include the inductor L and the capacitor C, or may only include the capacitor C. In the case of only one capacitor C, the inductor group formed by the first coupled inductor L101 and the second coupled inductor L101' and the capacitor C form an LC filter circuit.

A diagram of a single-phase inverter 200 based on a three-level NPC topology according to an embodiment of the present invention is described below with reference to FIG. 2 .

As shown in FIG. 2, the single-phase inverter 200 includes two three-level NPC topologies connected in parallel at both ends of the DC source Udc, that is, a first three-level NPC topology N201 and a second three-level NPC topology N201′ . Specifically, the first three-level NPC topology N201 includes diodes D201, D202, D203, D204, D205 and D206, power switching devices (hereinafter referred to as switches) S201, S202, S203 and S204, and capacitors C201 and C202. The second three-level NPC type topology N201' comprises diodes D201', D202', D203', D204', D205' and D206', switches S201', S202', S203' and S204', and capacitors C201' and C202' .

The single-phase inverter 200 also includes a first coupled inductor L201 connected to the output terminal P2 of the first three-level NPC topology N201, and a coupled inductor L201 connected to the output terminal P2' of the second three-level NPC topology N201'. The second coupled inductor L201'.

As far as the first three-level NPC topology N201 is concerned, when switching between positive level voltage and zero level voltage, the switch S201 acts and the switch S202 is normally on. Specifically, since the switch S202 is normally on, when the switch S201 is on, the current flows from the DC source Udc through the positive bus BUSP, the switch S201, the switch S202, the point P2 and the first coupled inductor L201, and then flows to the load R. At this time, the point P2 is a positive level voltage. Since the switch S202 is normally on, when the switch S201 is turned off, the current flows from the midpoint P1 through the diode D205, the switch S202, the point P2 and the first coupled inductor L201, and flows to the load R. At this time, the point P2 is at zero level Voltage.

When switching between negative level voltage and zero level voltage, the switch S204 acts and the switch S203 is normally on. Specifically, since the switch S203 is normally on, when the switch S204 is on, the current flows from the load R through the first coupling inductor L201, the point P2, the switch S203 and the switch S204, and flows to the negative bus BUSN. At this time, the point P2 is a negative level voltage. Since the switch S203 is normally on, when the switch S204 is turned off, the current flows from the load R through the first coupling inductor L201, point P2, switch S203 and diode D206, and flows to the midpoint P1. At this time, the point P2 is zero current. flat voltage.

The second three-level NPC-type topology N201' has a similar structure to the first three-level NPC-type topology N201, so the working principles are similar, and will not be repeated here.

Switches S201, S202, S203, S204, S205 and S206 of the first three-level NPC-type topology N201 and switches S201', S202', S203', S204', S205' and switches of the second three-level NPC-type topology N201' S206' is switched under the drive of a corresponding drive signal from a drive circuit (not shown in FIG. 2 ).

According to this embodiment, the phase of the modulation wave of the drive signal for the switches S201, S202, S203 and S204 of the first three-level NPC topology N201 is the same as that of the switch S201' for the second three-level NPC topology N201'. , S202', S203' and S204' have the same phase of the modulated waves. The phase of the carrier of the drive signal for the switches S201', S202', S203' and S204' of the first three-level NPC-type topology N201 is different from that of the switches S201', S202 for the second three-level NPC-type topology N201' ', S203' and S204', the phases of the carrier waves differ by a certain angle. Preferably, the difference is 180 degrees, that is, the angle obtained by dividing 360 degrees by the number (ie, 2) of the three-level NPC type topology.

Preferably, the first coupled inductor L201 and the second coupled inductor L201' may be arranged to be coupled in reverse. By reverse coupling these two coupled inductors L201 and L201', it is possible to completely cancel the magnetic field generated by the fundamental frequency in the current output from point P2 and the current output from point P2' and partially cancel the two output currents The magnetic field generated by the harmonics.

Similar to the single-phase inverter 100 shown in FIGS. 1A and 1B , the single-phase inverter 200 may further include an inductor L and a capacitor C. Referring to FIG. In this case, the inductor group composed of the first coupled inductor L201 and the second coupled inductor L201' together with the inductor L and the capacitor C forms an LCL filter circuit for the first three-level NPC topology The current output by N201 and the second three-level NPC topology N201' is filtered.

Similar to the single-phase inverter 100 shown in FIG. 1A , the single-phase inverter 200 may not include the inductor L and the capacitor C, or may include the capacitor C only.

The single-phase inverter composed of two three-level T-type topologies is described above with reference to FIG. 1A , and the single-phase inverter composed of two three-level NPC topologies is described with reference to FIG. 2 . However, it can be understood that more than two three-level T-type topologies, or more than two three-level NPC topologies may be used to form a single-phase inverter system. Alternatively, more than two two-level topologies or a single-phase inverter system composed of more than two two-level topologies may be used.

A single-phase inverter system 300 composed of multiple topological structures according to an embodiment of the present invention will be described below with reference to FIG. 3 . As shown in FIG. 3 , the single-phase inverter system 300 includes 2K single-phase inverter modules, where K is an integer greater than or equal to 1. Each of the single-phase inverter module 1 to the single-phase inverter module 2K may be a three-level T-type topology. Alternatively, each of the single-phase inverter modules 1 to 2K may be a three-level NPC topology. Or each of the single-phase inverter module 1 to the single-phase inverter module 2K may be a two-level topology.

The single-phase inverter system 300 also includes a filter circuit. The filter circuit may have a structure as shown in FIG. 4A , that is, it includes 2K coupled filter inductors. Alternatively, the filter circuit may have a structure as shown in FIG. 4B , that is, it includes 2K coupled filter inductors and capacitors C to form an LC filter circuit. Alternatively, the filter circuit may have a structure as shown in FIG. 4C , that is, it includes 2K coupled filter inductors, capacitors C and inductors L to form an LCL filter circuit.

In the single-phase inverter 300 shown in FIG. 3 , the single-phase inverter modules 1 to 2K can be connected in parallel to a DC source (not shown in FIG. 3 ). The phases of the modulated waves of the driving signals used to drive the single-phase inverter modules are the same, and the phases of the carrier waves of the driving signals are sequentially different by a predetermined angle. The predetermined angle is preferably 360°/2K. The outputs of 2K coupled inductors (as shown in FIGS. 4A to 4C ) are connected together. The 2K coupled inductors are arranged in the same winding direction to completely cancel the magnetic field generated by the fundamental frequency of the output current of the 2K single-phase inverter modules and partially cancel the magnetic field generated by the harmonic in the output current.

A three-phase inverter 500 according to an embodiment of the present invention is described below with reference to FIG. 5 .

As shown in Fig. 5, the three-phase inverter 500 includes two three-phase inverter modules connected in parallel at both ends of the DC source Udc, namely a first three-phase inverter module 501 and a second three-phase inverter module 501'. Specifically, the first three-phase inverter module 501 includes an A-phase inverter circuit, a B-phase inverter circuit, and a C-phase inverter circuit respectively composed of a three-level T-type topology. Similarly, the second three-phase inverter module 501' also includes an A'-phase inverter circuit, a B'-phase inverter circuit and a C'-phase inverter circuit respectively composed of a three-level T-type topology.

In order not to complicate the labeling of the drawings, the labels of the various power switching devices and diodes are not shown in FIG. 5 . In addition, the power switching devices and diodes used in FIG. 5 may be similar to those used in FIG. 1A , and will not be repeated here.

Three-phase inverter 500 also includes coupled inductors LA, LA', LB, LB', LC, and LC'. The output point PA of the A-phase inverter circuit is connected to the coupling inductor LA, the output point PB of the B-phase inverter circuit is connected to the coupling inductor LB, and the output point PC of the C-phase inverter circuit is connected to the coupling inductor LC. Similarly, the output point PA' of the A' phase inverter circuit is connected to the coupled inductor LA', the output point PB' of the B' phase inverter circuit is connected to the coupled inductor LB', and the output point of the C' phase inverter circuit PC' is connected to coupled inductor LC'.

The output terminals of coupled inductors LA and LA' are connected together, the output terminals of coupled inductors LB and LB' are connected together, and the output terminals of coupled inductors LC and LC' are connected together.

As shown in Figure 5, the output terminals of the coupled inductors LA and LA', the output terminals of the coupled inductors LB and LB', and the output terminals of the coupled inductors LC and LC' are respectively connected to the corresponding inductors and capacitors C to The LCL circuit is formed accordingly.

As discussed before, optionally, the three-phase inverter system 500 may not include the inductor L and the capacitor C, or may only include the capacitor C. In the case of including only one capacitor C, an LC filter circuit is formed.

The A-phase inverter circuit, the B-phase inverter circuit, the C-phase inverter circuit, the A'-phase inverter circuit, the B'-phase inverter circuit and the C'-phase inverter circuit work under the drive of their respective driving signals. The phases of the modulated wave of the drive signal for the A-phase inverter circuit, the modulated wave of the drive signal for the B-phase inverter circuit, and the modulated wave of the drive signal for the C-phase inverter circuit are sequentially different by 120°.

The phase of the modulated wave of the drive signal of the A'-phase inverter circuit is the same as that of the modulated wave of the drive signal of the A-phase inverter circuit. The phase of the modulated wave of the drive signal of the B'-phase inverter circuit is the same as that of the modulated wave of the drive signal of the B-phase inverter circuit. The phase of the modulated wave of the drive signal of the C'-phase inverter circuit is the same as that of the modulated wave of the drive signal of the C-phase inverter circuit. The phase of the modulated wave associated with the A-phase inverter circuit and the A'-phase inverter circuit, the phase of the modulated wave associated with the B-phase inverter circuit and the B'-phase inverter circuit, and the phase of the modulated wave associated with the C-phase inverter circuit and the C'-phase inverter circuit The phases of the modulated waves associated with the phase inverter circuits differ by 120 degrees sequentially.

The carrier of the drive signal for the A-phase inverter circuit and the carrier of the drive signal for the A'-phase inverter circuit are out of phase by a predetermined angle. The carrier of the drive signal for the B-phase inverter circuit and the carrier of the drive signal for the B'-phase inverter circuit are different in phase by a predetermined angle. The carrier of the drive signal for the C-phase inverter circuit and the carrier of the drive signal for the C'-phase inverter circuit are different in phase by a predetermined angle. Preferably, the predetermined angle is 180 degrees.

Preferably, the coupled inductor LA is negatively coupled to the coupled inductor LA', the coupled inductor LB is negatively coupled to the coupled inductor LB', and the coupled inductor LC is negatively coupled to the coupled inductor LC'.

Although the above describes the three-phase inverter 500 constituted by the three-level T-type topology with reference to FIG. 5 . However, according to the previous description, it can be understood that other three-level topologies, such as NPC topologies, can also be used to form a three-phase inverter. Alternatively, a three-phase inverter can also be formed by a two-level topology.

A three-phase inverter system 600 composed of multiple topological structures according to an embodiment of the present invention will be described below with reference to FIG. 6 . As shown in FIG. 6 , the three-phase inverter system 600 includes 2K three-phase inverter modules, where K is an integer greater than or equal to 1. Each of the three-phase inverter modules 1 to 2K may be similar to the three-phase inverter module 501 or the three-phase inverter module 501' shown in FIG. 5 . Alternatively, each of the three-phase inverter modules 1 to 2K may be a three-phase inverter module composed of a three-level NPC topology. Alternatively, each of the three-phase inverter modules 1 to 2K may be a three-phase inverter module composed of a two-level topology.

The three-phase inverter system 600 also includes a filter circuit A, a filter circuit B and a filter circuit C. Each of the filter circuit A, the filter circuit B and the filter circuit C may have a structure as shown in FIG. 4A , that is, include 2K coupled filter inductors. Alternatively, each of the filter circuit A, the filter circuit B and the filter circuit C may have a structure as shown in FIG. 4B , that is, include 2K coupled filter inductors and capacitors C to form an LC filter circuit. Or each of filter circuit A, filter circuit B and filter circuit C may have a structure as shown in FIG. 4C , that is, include 2K coupled filter inductors and capacitors C and inductors L to form an LCL filter circuit.

In the three-phase inverter 600 shown in FIG. 6 , the three-phase inverter modules 1 to 2K can be connected in parallel to a DC power source (not shown in FIG. 6 ).

The phases of the modulated waves used to drive the drive signals of phase A in the three-phase inverter modules 1 to 2K are the same, and the phases of the modulated waves used to drive the drive signals of phase B in the three-phase inverter modules 1 to 2K are the same, The phases of the modulated waves of the drive signals for driving the C-phase in the three-phase inverter modules 1 to 2K are the same, and the phases are different from each other by 120 degrees.

The phases of the carriers of the driving signals used to drive the A-phases of the three-phase inverter modules 1 to 2K are sequentially different from each other by a predetermined angle. Similarly, the phases of the carriers of the drive signals used to drive the B-phases of the three-phase inverter modules 1 to 2K are sequentially different from each other by a predetermined angle. The phases of the respective carriers of the signal sequentially differ by a predetermined angle. The aforementioned predetermined angle is preferably 360°/2K.

A three-phase inverter system 700 according to an embodiment of the present invention is described below with reference to FIG. 7 . The difference between FIG. 7 and FIG. 6 is that the filter circuit in FIG. 7 is different from the filter circuit in FIG. 6 . Each filter circuit in FIG. 7 includes two coupled inductors, while each filter circuit in FIG. 6 includes 2K coupled inductors. Another difference between Figure 7 and Figure 6 lies in the way the filter circuit is connected to the load. The output terminals of each filter circuit A in FIG. 7 are connected together, the output terminals of each filter circuit B are connected together, and the output terminals of each filter circuit C are connected together.

The functions of the three-phase inverter modules 1 to 2K in FIG. 7 and the three-phase inverter modules 1 to 2K in FIG. 6 are similar to the driving signals used, and will not be repeated here.

The power switching device described in this article (sometimes referred to as a switch) can be an insulated gate bipolar transistor (Insulated Gate Bipolar Transistor, IGBT), a metal oxide semiconductor field effect transistor (Metal-Oxide-Semiconductor Field Effect Transistor, MOSFET), Gate Turn-off Thyristor (Gate Turn-off Thyristor, GTO) or any other suitable switching device, etc.

The two power switching devices in the middle auxiliary bridge arm of the above-mentioned T-shaped circuit topology can be connected by a common collector or a common emitter. The middle points of the upper and lower module busbar capacitors can be connected at one point or not. In addition, in the T-type topology (whether it is single-phase or three-phase) described above with reference to the accompanying drawings, the parallel diodes of the power switching devices on the auxiliary bridge arm can be connected with common anode or common cathode. The midpoints of the upper and lower module bus capacitors can be connected at one point or not. Optionally, the filtered single-phase or three-phase voltage output can be connected to a single-phase or three-phase transformer.

In addition, the inverter or inverter system according to the embodiments of the present invention can be applied to, for example, a photovoltaic grid-connected inverter.

The invention adopts the coupled inductor PWM carrier phase-shifting technology, which not only reduces the loss of power devices, but also greatly reduces the loss and cost of the output inductor, improves the efficiency of the inverter, and reduces the overall cost of the inverter. Great application value and broad market prospects.

It should be emphasized that the term "comprising/comprising" when used herein refers to the presence of a feature, element, step or component, but does not exclude the presence or addition of one or more other features, elements, steps or components.

The present invention and its advantages, but it should be understood that various changes, substitutions and alterations can be made therein without departing from the spirit and scope of the invention as defined by the appended claims. Moreover, the scope of the present invention is not limited to the specific embodiments of the procedures, devices, means, methods and steps described in the specification. Those of ordinary skill in the art will readily appreciate from the disclosure of the present invention that existing and future developments that perform substantially the same function or obtain substantially the same results as the corresponding embodiments herein can be used in accordance with the present invention. process, equipment, means, method or steps. Accordingly, the appended claims are intended to include within their scope such processes, means, means, methods or steps.

Claims (24)

1. A single-phase inverter, comprising: The first single-phase inverter circuit and the second single-phase inverter circuit are configured to be connected in parallel to both ends of the DC source and have the same structure; a drive circuit configured to drive the first single-phase inverter circuit with a first drive signal and drive the second single-phase inverter circuit with a second drive signal, the first drive signal being composed of the first modulated wave and the first Carrier modulation, the second drive signal is modulated by a second modulation wave and a second carrier, and the first modulation wave and the second modulation wave have the same phase; and The first coupled inductor and the second coupled inductor, the input terminal of the first coupled inductor receives the current output by the first single-phase inverter circuit, and the input terminal of the second coupled inductor receives the first coupled inductor Two single-phase inverter circuits output current, and the first coupled inductor and the second coupled inductor are reversely coupled and their output terminals are connected together. 2. The single-phase inverter according to claim 1, wherein the phase of the first carrier wave and the phase of the second carrier wave are different by 180 degrees. 3. The single-phase inverter according to claim 1, wherein the first single-phase inverter circuit and the second single-phase inverter circuit are two-level topology or three-level topology. 4. The single-phase inverter according to claim 3, wherein the three-level topology is a three-level T-type topology or a three-level neutral-point clamped topology. 5. The single-phase inverter according to any one of claims 1 to 4, further comprising: A capacitor connected to output terminals of the first coupled inductor and the second coupled inductor connected together to form an LC filter circuit. 6. The single-phase inverter according to any one of claims 1 to 4, further comprising: A capacitor and an inductor are both connected to the connected output ends of the first coupled inductor and the second coupled inductor to form an LCL filter circuit. 7. A single-phase inverter system, comprising K single-phase inverters according to claim 1, K is an integer greater than or equal to 1, wherein K said first coupled inductors and K said The outputs of the second coupled inductors are connected together. 8. The single-phase inverter system according to claim 7, wherein the phases of the K first carrier waves and the K second carrier waves are sequentially different by 360/K degrees. 9. The single-phase inverter system according to claim 7, wherein, the K first single-phase inverter circuits and the K second single-phase inverter circuits are two-level topology or three-voltage topology flat topology. 10. The single-phase inverter system according to claim 9, wherein the three-level topology is a three-level T-type topology or a three-level neutral-point clamped topology. 11. The single-phase inverter system according to any one of claims 7 to 10, further comprising: A capacitor connected to output terminals of the K first coupled inductors and the K second coupled inductors connected together to form an LC filter circuit. 12. The single-phase inverter system according to any one of claims 7 to 10, further comprising: The capacitor and the inductor are both connected to the output ends where the K first coupled inductors and the K second coupled inductors are connected together to form an LCL filter circuit. 13. A three-phase inverter comprising: The first three-phase inverter circuit and the second three-phase inverter circuit are configured to be connected in parallel to both ends of the DC source and have the same structure, wherein the first three-phase inverter circuit includes a first A-phase inverter circuit, a second A-phase inverter circuit, and a second three-phase inverter circuit. A B-phase inverter circuit and a first C-phase inverter circuit, the second three-phase inverter circuit includes a second A-phase inverter circuit, a second B-phase inverter circuit and a second C-phase inverter circuit; A drive circuit configured to drive the first A-phase inverter circuit, the first B-phase inverter circuit, and the first A-phase inverter circuit with a first A-phase drive signal, a first B-phase drive signal, and a first C-phase drive signal The first C-phase inverter circuit, and drive the second A-phase inverter circuit, the second B-phase inverter circuit with the second A-phase drive signal, the second B-phase drive signal and the second C-phase drive signal respectively The inverter circuit and the second C-phase inverter circuit modulate the phases of the first A-phase modulation wave used for the first A-phase drive signal and the second A-phase modulation wave used for modulating the second A-phase drive signal Similarly, the phase of the first B-phase modulation wave used to modulate the first B-phase drive signal is the same as that of the second B-phase modulation wave used to modulate the second B-phase drive signal, and the first C-phase drive signal is modulated The phase of the first C-phase modulation wave used is the same as that of the second C-phase modulation wave used to modulate the second C-phase drive signal, An A-phase filter circuit including a first A-phase coupled inductor and a second A-phase coupled inductor; A B-phase filter circuit including a first B-phase coupled inductor and a second B-phase coupled inductor; A C-phase filter circuit including a first C-phase coupled inductor and a second C-phase coupled inductor; Wherein, the input terminals of the coupled inductor respectively receive the first A-phase inverter circuit, the second A-phase inverter circuit, the first B-phase inverter circuit, and the second B-phase inverter circuit. circuit, the corresponding output currents of the first C-phase inverter circuit and the second C-phase inverter circuit, the first A-phase coupled inductor and the second A-phase coupled inductor are reversely coupled and their The output ends are connected together, the first B-phase coupled inductor and the second B-phase coupled inductor are reversely coupled and their output ends are connected together, the first C-phase coupled inductor and the second The C-phase coupled inductors are coupled in anti-phase and their outputs are connected together. 14. The three-phase inverter according to claim 13, wherein the first A-phase carrier used for modulating the first A-phase driving signal, and the first B-phase carrier used for modulating the first B-phase driving signal The phase of the first C-phase carrier used for modulating the first C-phase driving signal is the same as that of the second A-phase carrier used for modulating the second A-phase driving signal, and the second A-phase carrier used for modulating the second B-phase driving signal. The phases of the two B-phase carriers and the second C-phase carrier used to modulate the second C-phase drive signal are the same but different from those of the first A-phase carrier, the second A-phase carrier and the third A-phase carrier 180 degrees out of phase. 15. The three-phase inverter according to claim 13, wherein the first A-phase inverter circuit, the first B-phase inverter circuit, the first C-phase inverter circuit, the first The two A-phase inverter circuits, the second B-phase inverter circuit and the second C-phase inverter circuit are all two-level topology or three-level topology. 16. The three-phase inverter according to claim 15, wherein the three-level topology is a three-level T-type topology or a three-level neutral-point clamped topology. 17. A three-phase inverter according to any one of claims 13 to 16, wherein, The A-phase filter circuit further includes: an A-phase capacitor connected to output terminals of the first A-phase coupled inductor and the second A-phase coupled inductor connected together to form an A-phase LC filter circuit ; The B-phase filter circuit further includes: a B-phase capacitor connected to output ends of the first B-phase coupled inductor and the second B-phase coupled inductor connected together to form a B-phase LC filter circuit ; and/or The C-phase filter circuit further includes: a C-phase capacitor connected to output ends of the first C-phase coupled inductor and the second C-phase coupled inductor connected together to form a C-phase LC filter circuit . 18. A three-phase inverter according to any one of claims 13 to 16, wherein, The A-phase filter circuit further includes: an A-phase capacitor and an A-phase inductor, both of which are connected to output ends of the first A-phase coupled inductor and the second A-phase coupled inductor connected together to form an A-phase Phase LCL filter circuit; The B-phase filter circuit further includes: a B-phase capacitor and a B-phase inductor, both of which are connected to output terminals connected together of the first B-phase coupled inductor and the second B-phase coupled inductor to form a B-phase Phase LCL filter circuit; and/or The C-phase filter circuit further includes: a C-phase capacitor and a C-phase inductor, both of which are connected to output ends of the first C-phase coupled inductor and the second C-phase coupled inductor connected together to form a C-phase Phase LCL filter circuit. 19. A three-phase inverter system, comprising: K three-phase inverters according to claim 13, K is an integer greater than or equal to 1, wherein, the K first A-phase coupled inductors and The output terminals of the K second A-phase coupled inductors are connected together, the output terminals of the K first B-phase coupled inductors and the K second B-phase coupled inductors are connected together, and K The output terminals of the first C-phase coupled inductors and the K second C-phase coupled inductors are connected together. 20. The three-phase inverter system according to claim 19, wherein the phases of the carrier waves used to modulate the drive signals of each A-phase inverter circuits differ by 360/K degrees successively, and are used to modulate each B-phase inverter circuits The phases of the carriers of the driving signals of the drive signals differ by 360/K degrees sequentially, and the phases of the carrier waves of the driving signals used to modulate the C-phase inverter circuits differ by 360/K degrees sequentially. 21. The three-phase inverter system according to claim 19, wherein, K of the first A-phase inverter circuits, K of the first B-phase inverter circuits, and K of the first C-phase inverter circuits The inverter circuit, the K second A-phase inverter circuits, the K second B-phase inverter circuits and the K second C-phase inverter circuits are all two-level topology or three-level topology . 22. The three-phase inverter system according to claim 21, wherein the three-level topology is a three-level T-type topology or a three-level neutral-point clamped topology. 23. A three-phase inverter system according to any one of claims 19 to 22, further comprising: A-phase capacitors connected to output ends of the K first A-phase coupled inductors and the K second A-phase coupled inductors connected together to form an A-phase LC filter circuit; a B-phase capacitor connected to output terminals of the K first B-phase coupled inductors and the K second B-phase coupled inductors connected together to form a B-phase LC filter circuit; and A C-phase capacitor connected to output terminals of the K first C-phase coupled inductors and the K second C-phase coupled inductors connected together to form a C-phase LC filter circuit. 24. A three-phase inverter system according to any one of claims 19 to 22, further comprising: The A-phase capacitor and the A-phase inductor are both connected to the output terminals of the K first A-phase coupled inductors and the K second A-phase coupled inductors connected together to form an A-phase LCL filter circuit ; The B-phase capacitor and the B-phase inductor are both connected to output terminals connected together of the K first B-phase coupled inductors and the K second B-phase coupled inductors to form a B-phase LCL filter circuit ;as well as The C-phase capacitor and the C-phase inductor are both connected to the output terminals of the K first C-phase coupled inductors and the K second C-phase coupled inductors connected together to form a C-phase LCL filter circuit .

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