WO2016159517A1

WO2016159517A1 - H-bridge multilevel inverter

Info

Publication number: WO2016159517A1
Application number: PCT/KR2016/001934
Authority: WO
Inventors: 아쉬라프아흐무드; 박종후
Original assignee: 숭실대학교 산학협력단
Priority date: 2015-03-30
Filing date: 2016-02-26
Publication date: 2016-10-06
Also published as: KR20160117675A; KR101697855B1

Abstract

The present invention relates to an H-bridge multilevel inverter and provides an H-bridge multilevel inverter comprising: a first capacitor that is connected to an input power source and removes a ripple of a first DC power source supplied from the input power source; a first H-bridge inverter having two DC terminals connected to both terminals of the first capacitor, and a first AC terminal connected to a first terminal of a load; a second H-bridge inverter having a first AC terminal connected to a second AC terminal of the first H-bridge inverter in series, wherein a second DC power source is formed between two DC terminals thereof; a second capacitor having both terminals connected to the two DC terminals of the second H-bridge inverter, respectively; a voltage converter that has an input terminal connected to both terminals of the second capacitor, and drops a voltage from the second DC power source to a third DC power source; a third capacitor having both terminals connected to an output terminal of the voltage converter; and a third H-bridge inverter having two DC terminals connected to both terminals of the third capacitor, a first AC terminal connected to the second AC terminal of the second H-bridge inverter in series, and a second AC terminal connected to a second terminal of the load.

Description

H-bridge multi level inverter

The present invention relates to an H-bridge multi-level inverter, and more particularly, to an H-bridge multi-level inverter capable of generating a multi-level alternating output voltage.

Multi-level inverters can form multiple levels in the output voltage, making the output voltage close to sinusoidal. These multi-level inverters can achieve high efficiency output voltages by reducing the total harmonic distortion (THD) as the number of voltage levels increases and reducing the loss of switches.

In general, multi-level inverters are divided into diode-clamps, flying-capacitors, and H-bridge multi-level inverters. Among them, the H-bridge multi-level inverter is a structure in which a plurality of H-bridge inverters are connected in series, eliminating the need for clamping diodes or capacitors and grouping in H-bridge units, which is easy to expand and control. have.

However, such an H-bridge multi-level inverter requires a plurality of power sources corresponding to the number of the plurality of H-bridges. In order to solve this problem, there is a method of auxiliary power supply to the H-bridges of each stage from a single power source through a power converter such as a transformer, but in this case, the amount of power that the power converter and the H-bridge has to handle It becomes quite big.

The background technology of the present invention is disclosed in Korean Patent Registration No. 1230862 (2013.02.07).

The present invention provides an H-bridge multi-level inverter capable of generating a multi-level alternating current output having high efficiency from a single input power source and reducing the power throughput of the auxiliary H-bridge inverter connected to the main H-bridge inverter. There is a purpose.

According to the present invention, a first capacitor is connected to first and second ends of an input power source, respectively, and a first capacitor for removing ripple of a first DC power source supplied from the input power source, and first and second terminals. A first H-bridge inverter having a DC terminal connected to the first and second ends of the first capacitor, and a first AC terminal connected to the first end of the load, and a first AC terminal being the first H-bridge inverter A second H-bridge inverter connected in series with a second AC terminal of the second DC power source, wherein a second DC power source is formed between the first and second DC ends, and the first and second ends of the first H-bridge inverter; And a second capacitor connected to a second DC terminal, respectively, to remove the ripple of the second DC power source, and first and second input terminals respectively connected to the first and second terminals of the second capacitor. 2 a voltage converter for stepping down the DC power supply to the third DC power supply and outputting it between the first and second output terminals; A third capacitor connected to the first and second output terminals of the voltage converter, respectively, to remove the ripple of the third DC power source, and the first and second DC terminals connected to the first and second terminals of the third capacitor; H-bridges, each of which includes a third H-bridge inverter connected to a second AC terminal of the second H-bridge inverter, the first AC terminal being connected in series, and the second AC terminal being connected to the second terminal of the load. Provide a multi-level inverter.

Here, the voltage converter may be configured as a transformer-type isolated converter or a buck converter.

In addition, the voltage converter may include a first switch having a control signal applied to a first stage and a second stage connected to a first stage of the second capacitor, and a control signal applied to a first stage and the third stage being the A second switch connected to the second end of the second capacitor, a first diode connected at the anode to the third end of the first switch, a second diode connected at the cathode of the second switch, and an anode A third diode connected to the anode of the second diode and a cathode connected to the cathode of the first diode; a first end connected to the cathode of the first diode; and a second end connected to the first end of the third capacitor. The connected first inductor may include a second inductor connected to an anode of the second diode and a second end connected to the second terminal of the third capacitor.

The first H-bridge inverter may output an AC voltage having the same switching frequency as the operating frequency of the load.

According to the H-bridge multi-level inverter according to the present invention, it is possible to generate a multi-level alternating current output having high efficiency from a single input power supply and to reduce the power throughput of the auxiliary H-bridge inverter connected to the main H-bridge inverter. This reduces cost and volume, and improves the efficiency and reliability of the system.

1 is a block diagram of an H-bridge multi-level inverter according to an embodiment of the present invention.

FIG. 2 is a diagram illustrating the voltage converter of FIG. 1 in detail.

FIG. 3 is a diagram illustrating individual DC voltages input to the plurality of H-bridge inverters shown in FIG. 1.

FIG. 4 is a diagram illustrating individual AC voltages output from the plurality of H-bridge inverters shown in FIG. 1.

FIG. 5 is a diagram illustrating a final output waveform formed by superimposing three waveforms shown in FIG. 4.

DETAILED DESCRIPTION Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings so that those skilled in the art may easily implement the present invention.

1 is a block diagram of an H-bridge multi-level inverter according to an embodiment of the present invention. H-bridge multi-level inverter 100 according to an embodiment of the present invention is the first capacitor 120, the first H-bridge inverter 130, the second H-bridge inverter 140, the second capacitor 150 , The voltage converter 160, the third capacitor 170, and the third H-bridge inverter 180.

The first capacitor 120 has first and second ends connected to the first and second ends of the input power source 110, respectively, and removes ripples of the first DC power supply Vs supplied from the input power source 110. And smooth. At this time, the voltage V _Main applied between both ends of the first capacitor 120 is equal to the size of the first DC power supply.

In the first H-bridge inverter 130, first and second DC terminals are connected to first and second terminals of the first capacitor 120, respectively. The first H-bridge inverter 130 converts the first DC power V _Main input to the first and second DC terminals into AC power by using internal switches, and outputs the AC power between the first and second AC terminals. . Since the structure of the H-bridge inverter composed of a plurality of switches is well known, a detailed description of its operation principle is omitted.

The first H-bridge inverter 130 and the second H-bridge inverter 140 are connected in series with the AC terminals. In the first H-bridge inverter 130, a first AC end is connected to the first end of the load 10, and a second AC end is connected in series to the first AC end of the second H-bridge inverter 140. As described above, a structure in which AC outputs of a plurality of H-bridge inverters are connected in series to each other is known in the art, and an AC output voltage having a plurality of levels may be provided to the load 10 through the structure.

The first H-bridge inverter 130 corresponds to the H-bridge which is the main body of the multi-level inverter 100, and the AC voltage output from the first H-bridge inverter 130 is an operating frequency of the load 10. Has the same switching frequency as.

In general, the operating frequency of the AC load 10 is 60 Hz. Since the first H-bridge inverter 130 may be implemented to output an AC voltage of 60 Hz, high speed switching is not necessary, and thus switching loss is low.

Of course, to supply a multi-level alternating current output to the load 10, an auxiliary H-bridge inverter, i.e., a second and third H-bridge inverter 180, at the next stage of the first H-bridge inverter 130. Performs higher speed switching (ex, 10-20kHz). Here, the switching frequency of the AC voltage output between each of the first and second AC terminals increases as the first to third H-

bridge inverters

130, 140, and 180 become higher.

The second H-bridge inverter 140 has a first AC terminal connected in series with the second AC terminal of the first H-bridge inverter 130, and the second AC terminal is serially connected with the first AC terminal of the third H-bridge inverter 180. The second DC power source V _Aux1 is formed between the first and second DC terminals. The voltage of the second DC power supply V _Aux1 is smoothed in the second capacitor 150.

The second capacitor 150 has a first stage and a second stage connected to the first and second DC terminals of the second H-bridge inverter 140, respectively, to remove the ripple of the second DC power supply V _Aux1 . To the voltage converter 160. The voltage converter 160 may be implemented as a DC-DC converter.

The voltage converter 160 includes first and second input terminals connected to first and second ends of the second capacitor 150, respectively, and includes a second DC power supply V _Aux1 connected to both ends of the second capacitor 150. Is _stepped down by a third DC power supply (V _Aux2 ) and output between the first and second output terminals.

The voltage converter 160 serves as an auxiliary power supply for supplying a DC voltage to the third H-bridge inverter 180. The voltage converter 160 may be composed of a conventional transformer type isolated converter or a buck converter, a modified isolated buck converter, and the like, capable of stepping down a voltage. The configuration of the modified buck converter is a transformerless isolated buck converter comprising at least two inductors, which will be described in detail later.

The third capacitor 170 has first and second ends connected to the first and second output terminals of the voltage converter 160, respectively, and has a ripple of the third DC power source V _Aux2 output from the voltage converter 160. Remove it.

In the third H-bridge inverter 180, first and second DC terminals are connected to first and second ends of the third capacitor 170, respectively. The third H-bridge inverter 180 converts the third DC power V _Aux2 input to the first and second DC terminals into AC power by using the operations of the internal switches, and outputs the alternating current between the first and second AC terminals. .

The third H-bridge inverter 180 has a first AC terminal connected in series with a second AC terminal of the second H-bridge inverter 140, and the second AC terminal is connected to the second terminal of the load 10. Accordingly, a stepped multi-level AC voltage waveform is output between the first AC terminal of the first H-bridge inverter 130 and the second AC terminal of the third H-bridge inverter 190, and the AC voltage waveform is a load ( 10) is supplied with AC power.

According to the configuration of FIG. 1, the asymmetric voltages Vmain, Vaux1, and Vaux2 are generated at each stage, and synthesized through the H-bridge inverters at each stage to generate an AC output having a stepped voltage waveform to load 10. Supplies). Asymmetrical voltages generally have multiples of one another.

In the configuration of FIG. 1, the first H-bridge inverter 130 is implemented to output an AC voltage having the same switching frequency as the operating frequency ex, 60 Hz of the load 10, and the second H-bridge inverter 140. And the third H-bridge inverter 180 performs high speed switching to output an AC voltage having a high frequency. Of course, the AC voltage output from the third H-bridge inverter 180 has a higher frequency than the second H-bridge inverter 140. In the embodiment of the present invention, as these three output waveforms are superimposed and output, AC power having multiple levels may be supplied to the load 10.

In the embodiment of the present invention, the AC output finally output through the plurality of H-bridge inverters is a concept including an AC current output or grid-connected renewable energy generation power for motor control. In the embodiment of the present invention as described above, the plurality of H-bridge inverters have a structure in which AC terminals are connected to each other in series, and the H-bridge inverter unit used may have three stages as shown in FIG.

The overall power flow in the multi-level inverter according to the embodiment of the present invention as shown in FIG. 1 can be known by referring to the arrow. According to an embodiment of the present invention, the flow of power is applied to the first H-bridge inverter 130, the second H-bridge inverter 140, the voltage converter 160, and the third H-bridge inverter 180 at the input power source 110. It can be seen that the path occurs.

In the conventional multi-level inverter, if the auxiliary power is directly supplied from a single input power supply (main power supply) and provided to the auxiliary H-bridge inverter, an embodiment of the present invention provides that the power provided from the input power supply is the first H-bridge inverter. Via 130 is provided to the auxiliary power source, i.e., voltage converter 160, via second H-bridge inverter 140 in the intermediate stage.

As described above, in FIG. 1, since the intermediate stage H-bridge inverter 140 of the two H-

bridge inverters

140 and 180 used as auxiliary supplies power to the front end of the voltage converter 160 corresponding to the auxiliary power source. The power throughput of the auxiliary H-bridge inverter connected to the main H-bridge inverter can be reduced.

In such a structure, the first H-bridge inverter 130 may generate about 90% of the total AC output supplied to the load 10, and the remaining second and third H-bridge inverters 180 may each have a power of 5%. Can produce power in%. That is, most of the power supplied to the load 10 may be produced through the first H-bridge inverter 130.

FIG. 2 is a diagram illustrating the voltage converter of FIG. 1 in detail. The voltage converter 160 shown in FIG. 2 has a modified buck converter form. Its basic operation is the same as that of a conventional buck converter.

Hereinafter, the voltage converter 160 includes a first switch S1, a second switch S2, a first diode D1, a second diode D2, a third diode D3, a first inductor L1, A second inductor L2 is included.

The first voltage converter 160 has a form similar to that of a conventional buck converter. However, the conventional buck converter does not have an insulation function, but the voltage converter according to the present embodiment has an insulation function because it includes an inductor on the ground line. The voltage converter can also be configured as a bidirectional switch.

The first switch S1 is composed of a transistor or the like, and a control signal is applied to the first stage (gate stage), the second stage is connected to the first stage of the second capacitor 150, and the third stage is the first stage. It is connected to the anode of the diode D1.

The second switch S2 is composed of a transistor or the like and a control signal is applied to the first stage (gate stage), the third stage is connected to the second stage of the second capacitor 150, and the second stage is the second stage. It is connected to the cathode of the diode D2.

In the first diode D1, an anode is connected to the third end of the first switch S1, and a cathode is connected to the first end of the first inductor L1. The second diode D2 has a cathode connected to the second end of the second switch S2 and an anode connected to the first end of the second inductor L2. The third diode D3 has an anode connected to the anode of the second diode D2 and a cathode connected to the cathode of the first diode D1.

The first inductor L1 has a first end connected to the cathode of the first diode D1 and a second end connected to the first end of the second capacitor 150. The second inductor L2 has a first end connected to the anode of the second diode D2 and a second end connected to the second end of the second capacitor 150. The second inductor L2 separates the ground of the third H-bridge inverter 180 from the ground of the input power source 110 to secure insulation.

In this structure, when each switch is turned on, the first switch S1-> first diode D1-> first inductor L1-> third capacitor 170-> second inductor L2 A current flow occurs in the direction of the second diode D2 to the second switch S2. During turn-off, the direction is formed by the third diode D3 and the first inductor L1-> second capacitor 170-> second inductor L2-> third diode D3-> first Current flows in the inductor L1 direction. The voltage converter may mean including a capacitor.

When the switch is turned on, the inductor current increases, and when it is turned off, the inductor current decreases until the switch is turned on again.When the switch is turned on and off periodically, the voltage is smoothed by L and C to output the DC voltage. Can be. This principle is almost the same as the operation mode of the conventional buck converter, so the detailed description is omitted.

Hereinafter, the results of simulating the performance of the multi-level inverter according to the embodiment of the present invention will be described. In the simulation, the input power source 110 used Vs = 225V.

FIG. 3 is a diagram illustrating individual DC voltages input to the plurality of H-bridge inverters shown in FIG. 1. In the case of Figure 3 shows an example using a multiple of the asymmetric voltage.

Referring to FIG. 3, the DC power Vmain_DC input to the first H-bridge inverter 130 is the same 225V as the input power 110 and the DC power Vaux1_DC input to the second H-bridge inverter 140. Is 75V, which is 1/3 of Vmain_DC, and DC power (Vaux2_DC) input to the third H-bridge inverter 180 is observed as 25V, which is 1/3 of Vaux1_DC.

FIG. 4 is a diagram illustrating individual AC voltages output from the plurality of H-bridge inverters shown in FIG. 1. The AC outputs of the first to third H-

bridge inverters

130, 140 and 180 are represented by Vmain_AC, Vaux1_AC and Vaux2_AC, respectively. If the AC output Vmain_AC of the first H-bridge inverter 130 exhibits a switching frequency characteristic of 60 Hz, the AC outputs Vaux1_AC and Vaux2_AC of the second and third H-

bridge inverters

140 and 180 have higher frequency characteristics. It can be seen that represents. Of course, it can be seen that the frequency of the AC voltage output as the first to third H-bridge inverter (130, 140, 180) increases.

FIG. 5 is a diagram illustrating a final output waveform formed by superimposing three waveforms shown in FIG. 4. The final output waveform of FIG. 5 is a waveform actually applied to a load, and through the circuit configuration of FIG. 1, an AC voltage form having a total of 21 levels can be output. The final output frequency has a 60Hz component that is equal to the operating frequency of the load.

According to the H-bridge multi-level inverter according to the present invention as described above, it is possible to generate a multi-level alternating current output having high efficiency from a single input power source, and to control the power throughput of the auxiliary H-bridge inverter connected to the main H-bridge inverter. Can be reduced, reducing cost and volume, and improving the efficiency and reliability of the system.

Although the present invention has been described with reference to the embodiments shown in the drawings, this is merely exemplary, and it will be understood by those skilled in the art that various modifications and equivalent other embodiments are possible. Therefore, the true technical protection scope of the present invention will be defined by the technical spirit of the appended claims.

Claims

A first capacitor having first and second ends connected to first and second ends of input power, respectively, for removing ripple of the first DC power supplied from the input power;

A first H-bridge inverter having first and second DC ends connected to first and second ends of the first capacitor, respectively, and a first AC end connected to a first end of a load;

A second H-bridge inverter having a first AC terminal connected in series with a second AC terminal of the first H-bridge inverter and having a second DC power source formed between the first and second DC terminals;

A second capacitor having first and second ends connected to first and second DC ends of the second H-bridge inverter, respectively, to remove ripples of the second DC power source;

A first and second input terminals connected to first and second terminals of the second capacitor, respectively, and a voltage converter for stepping down the second DC power to a third DC power source and outputting the first and second output terminals;

A third capacitor having first and second ends connected to first and second output ends of the voltage converter, respectively, to remove ripple of the third DC power source; And

First and second DC terminals are connected to the first and second terminals of the third capacitor, respectively, and the first AC terminal is connected in series with the second AC terminal of the second H-bridge inverter, and the second AC terminal is connected to the load. And a third H-bridge inverter connected to the second stage of the H-bridge multi-level inverter.
The method according to claim 1,

The voltage converter,

H-bridge multi-level inverter consisting of a transformer-isolated converter or a buck converter.
The method according to claim 1,

The voltage converter,

A first switch having a control signal applied to a first stage and a second stage connected to a first stage of the second capacitor;

A second switch to which the control signal is applied to a first end and a third end is connected to a second end of the second capacitor;

A first diode having an anode connected to the third end of the first switch;

A second diode having a cathode connected to the second end of the second switch;

A third diode having an anode connected to the anode of the second diode and a cathode connected to the cathode of the first diode;

A first inductor having a first end connected to the cathode of the first diode and a second end connected to the first end of the third capacitor; And

An H-bridge multi level inverter comprising a second inductor having a first end connected to an anode of the second diode and a second end connected to a second end of the third capacitor.
The method according to claim 1,

And the first H-bridge inverter outputs an AC voltage having the same switching frequency as the operating frequency of the load.