A Boost Inverter Cascade Converter and Method for Suppressing Common-Mode DC Components

Abstract

The present invention provides a boost inverter cascaded converter and method for suppressing common-mode DC components, belonging to the technical field of aircraft airborne power supplies. The boost inverter cascaded converter of the present invention includes: the midpoint of the capacitor bridge arm of the three-phase inverter is connected in series with an inductor and connected to the external aircraft metal structure; the common terminal of the filter capacitors of the LC filter is led out as the neutral point of the three-phase inverter to connect the N line to the negative line of the low-voltage input side of the DC-DC converter; the midpoint of the capacitor bridge arm of the three-phase inverter is connected to the neutral line of the three-phase inverter and the negative line of the low-voltage input side of the DC-DC converter through a series-connected inductor. The present invention has low cost and simple structure, and does not require adding a fundamental frequency transformer and any complex active circuits or software algorithms, and can effectively improve the power density of the converter.

Description

Technical Field

[0001] The present invention relates to the technical field of aircraft on-board power supplies, and particularly to a boost inverter cascaded converter and method for suppressing common-mode DC components. Background Art

[0002] With the rapid development of multi-electric aircraft and all-electric aircraft, the types and quantities of on-board electrical equipment have increased significantly, and the requirements for power supply types and power supply quality have also become higher and higher. The on-board cascaded power converter is also more and more widely used in the aircraft secondary power distribution system.

[0003] In the aircraft power supply system, according to industry general standard specifications such as AC43.13-1B, ARP1870 and GJB181A-2012, the current return paths of aircraft electrical circuits include AC and DC power grounds, which are all connected to the aircraft metal structure, as Figure 1 shown.

[0004] Although this grounding scheme can reduce the volume and weight of the power supply system and simplify the installation and maintenance operations. However, for the on-board cascaded power converter, the short connection of the AC output neutral line and the DC input negative line of the DC-DC converter, under the influence of the distributed capacitance of the primary and secondary windings of the transformer, makes a common-mode interference conduction path appear in the cascaded system, resulting in a common-mode DC component in the AC output voltage, affecting the normal use of electrical equipment, and even damaging the on-board electrical equipment in extreme cases.

[0005] The prior art usually blocks the common-mode path by increasing the fundamental frequency transformer or auxiliary active circuit, etc., but will inevitably increase the volume, weight and complexity of the system, reduce the reliability of the power supply system, and limit the improvement of the power density of the power supply system. Summary of the Invention

[0006] In view of the above problems, the present invention proposes a boost inverter cascaded converter for suppressing common-mode DC components, including: a DC-DC converter, a three-phase inverter and an LC filter;

[0007] The midpoint of the capacitor bridge arm of the three-phase inverter is connected in series with an inductor and connected to the external aircraft metal structure;

[0008] The common terminal of the filter capacitors of the LC filter is led out as the neutral point N of the three-phase inverter and connected to the negative line of the low-voltage input side of the DC-DC converter;

[0009] The midpoint of the capacitor bridge arm of the three-phase inverter is connected to the neutral line of the three-phase inverter and the negative line of the low-voltage input side of the DC-DC converter through a series-connected inductor.

[0010] Optionally, the potential of the midpoint of the capacitor bridge arm of the three-phase inverter is clamped.

[0011] Optionally, the capacitive leg of the three-phase inverter is connected in parallel to the input side of the three-phase inverter.

[0012] Optionally, the three-phase inverter further includes a first leg, a second leg, and a third leg, and the capacitive leg, the first leg, the second leg, and the third leg of the three-phase inverter are connected in parallel in sequence.

[0013] The present invention also proposes a method for suppressing the common-mode DC component using the above boost-inverter cascaded converter, including: clamping the potential of the midpoint of the capacitive leg of the three-phase inverter.

[0014] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0015] For the boost-inverter cascaded converter proposed by the present invention, an inductor is connected in series at the midpoint of the capacitive leg of the three-phase inverter and connected to the external aircraft metal structure; the common terminal of the filter capacitors of the LC filter is led out as the neutral point of the three-phase inverter to connect the N line to the negative line of the low-voltage input side of the DC-DC converter; the midpoint of the capacitive leg of the three-phase inverter is connected to the neutral line of the three-phase inverter and the negative line of the low-voltage input side of the DC-DC converter through a series-connected inductor. This makes the present invention have low cost and simple structure, without the need to add a fundamental frequency transformer and any complex active circuits or software algorithms, and can effectively improve the power density of the converter. The inductor added in the present invention is located between the midpoint of the capacitive leg and the aircraft metal shell, realizing the decoupling of the above two points of potential, and the space vector modulation can still be used to control the inverter. The present invention is not affected by the topology of the pre-stage DC-DC converter and the parasitic parameters of the isolation transformer, and can ensure the reliable and stable operation of the cascaded converter. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 is a schematic structural diagram of the cascaded converter of the present invention in an aircraft environment;

[0017] Figure 2 is a schematic structural diagram of a boost-inverter cascaded converter for suppressing the common-mode DC component according to the present invention. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0018] Now, exemplary embodiments of the present invention will be described with reference to the accompanying drawings. However, the present invention can be implemented in many different forms and is not limited to the embodiments described herein. These embodiments are provided to disclose the present invention in detail and completely, and to fully convey the scope of the present invention to those skilled in the art. The terms in the exemplary embodiments shown in the drawings are not intended to limit the present invention. In the drawings, the same unit / element is denoted by the same reference numeral.

[0019] Unless otherwise specified, the terms used herein (including scientific and technical terms) have the ordinary meanings understood by those skilled in the relevant technical field. Additionally, it can be understood that terms defined in commonly used dictionaries should be construed to have meanings consistent with the context of their relevant fields, and should not be construed as idealized or overly formal meanings.

[0020] The present invention proposes a boost inverter cascaded converter for suppressing the common-mode DC component, as Figure 1 shown, including: a DC-DC converter, a three-phase inverter, and an LC filter;

[0021] The midpoint of the capacitor bridge arm of the three-phase inverter is connected in series with an inductor and connected to the external aircraft metal structure;

[0022] The common terminal of the filtering capacitors of the LC filter is led out as the neutral point of the three-phase inverter to connect the N line to the negative line of the low-voltage input side of the DC-DC converter;

[0023] The midpoint of the capacitor bridge arm of the three-phase inverter is connected to the neutral line of the three-phase inverter and the negative line of the low-voltage input side of the DC-DC converter through a series-connected inductor.

[0024] Among them, the potential of the midpoint of the capacitor bridge arm of the three-phase inverter is clamped.

[0025] The capacitor bridge arm of the three-phase inverter is connected in parallel on the input side of the three-phase inverter.

[0026] The three-phase inverter further includes a first bridge arm, a second bridge arm, and a third bridge arm, and the capacitor bridge arm, the first bridge arm, the second bridge arm, and the third bridge arm of the three-phase inverter are connected in parallel in sequence.

[0027] Specifically, the DC-DC converter includes a full-bridge inverter circuit, a transformer T1, a resonant cavity on the secondary side of the transformer T1, and a full-bridge uncontrolled rectifier and filter circuit on the output side of the resonant cavity. Among them, the full-bridge inverter circuit includes a first bridge arm and a second bridge arm connected in parallel. The first bridge arm includes MOS transistors Q1_1 and Q1_2 connected in series, and the second bridge arm includes MOS transistors Q1_3 and Q1_4 connected in series; the output of the full-bridge inverter circuit is connected to the primary winding of the transformer T1. The secondary side of the transformer T1 includes a resonant capacitor Cr and a resonant inductor Lr connected in series, and an exciting inductor Ls connected in parallel at the input end of the uncontrolled rectifier bridge. The rectifier bridge after the exciting inductor adopts a full-bridge form. The rectifier bridge includes a first diode D1, a second diode D2, a third diode D3, and a fourth diode D4. The output of the rectifier bridge is connected to the three-phase inverter;

[0028] The three-phase inverter includes a bus output capacitor bridge arm, a neutral line series inductor L1, a first bridge arm, a second bridge arm, and a third bridge arm. The bus output capacitor bridge arm includes a first capacitor C1 and a second capacitor C2 connected in series. The first bridge arm includes an MOS transistor Q2_1 and an MOS transistor Q2_2 connected in series. The second bridge arm includes an MOS transistor Q2_3 and an MOS transistor Q2_4 connected in series. The third bridge arm includes an MOS transistor Q2_5 and an MOS transistor Q2_6 connected in series.

[0029] The present invention clamps the potential of the midpoint of the DC bus capacitor bridge arm to achieve common-mode DC component suppression.

[0030] The present invention is the first application in the special background of an aircraft power supply system.

[0031] In the present invention, the conduction path of common-mode interference is that the common-mode signal generated by the three-phase inverter is injected into the negative line of the low-voltage side input of the DC-DC converter through the ground wire, conducted through the MOS transistor Q1_4 of the second bridge arm of the DC-DC converter to the distributed capacitance, resonant cavity, and rectifier bridge arm of the primary and secondary windings of the DC-DC converter, and rectified to generate a common-mode DC component, which is superimposed on the sinusoidal voltage output by the inverter.

[0032] The pre-stage of the present invention is not limited to an isolated LLC converter. For any airborne cascaded power converter with an isolated DC-DC converter as the pre-stage and a three-phase inverter as the post-stage, the suppression of the common-mode DC component can be achieved.

[0033] The boost-inverter cascaded converter proposed by the present invention leads out the neutral line N by taking the common end of the filtering capacitor of the output LC filter of the converter as the neutral point of the three-phase inverter and connecting it to the negative line of the low-voltage input side of the DC-DC converter; after connecting the midpoint series inductor of the capacitor bridge arm of the three-phase inverter, it is connected in parallel with the neutral line of the three-phase inverter and the negative line of the low-voltage input side of the DC-DC converter to the external aircraft metal structure. The present invention has low cost and a simple structure, does not require adding a fundamental frequency transformer and any complex active circuits or software algorithms, and can effectively improve the power density of the converter. The inductor added in the present invention is located between the midpoint of the capacitor bridge arm and the aircraft metal shell, realizing the decoupling of the above two points of potential, and the space vector modulation can still be used to control the inverter. The present invention is not affected by the topology of the pre-stage DC-DC converter and the parasitic parameters of the isolation transformer, and can ensure the reliable and stable operation of the cascaded converter.

[0034] The present invention also proposes a method for suppressing the common-mode DC component using the above boost-inverter cascaded converter, including: clamping the potential of the midpoint of the capacitor bridge arm of the three-phase inverter.

[0035] The present invention clamps the potential of the midpoint of the bus output capacitor bridge arm to achieve common-mode DC component suppression.

[0036] The present invention is applied for the first time in the specific context of an aircraft power supply system.

[0037] Those skilled in the art should understand that the embodiments of the present invention can be provided as a method, a system, or a computer program product. Therefore, the present invention can take the form of a completely hardware embodiment, a completely software embodiment, or an embodiment combining software and hardware aspects. Moreover, the present invention can take the form of a computer program product implemented on one or more computer-usable storage media (including but not limited to disk memory, CD-ROM, optical memory, etc.) that contain computer-usable program code.

[0038] The present invention is described with reference to the flowcharts and / or block diagrams of methods, apparatuses (systems), and computer program products according to the embodiments of the present invention. It should be understood that each flow and / or block in the flowcharts and / or block diagrams, as well as the combination of flows and / or blocks in the flowcharts and / or block diagrams, can be realized by computer program instructions. These computer program instructions can be provided to the processor of a general-purpose computer, a special-purpose computer, an embedded processor, or other programmable data processing devices to generate a machine, so that the instructions executed by the processor of the computer or other programmable data processing devices generate means for realizing the functions specified in one Figure 1 flow or multiple flows and / or blocks Figure 1 block or multiple blocks.

[0039] These computer program instructions can also be stored in a computer-readable memory that can direct a computer or other programmable data processing device to work in a specific manner, so that the instructions stored in the computer-readable memory generate a manufactured article including instruction means, and the instruction means realizes the functions specified in one Figure 1 flow or multiple flows and / or blocks Figure 1 block or multiple blocks.

[0040] These computer program instructions can also be loaded onto a computer or other programmable data processing device, so that a series of operation steps are executed on the computer or other programmable device to generate a computer-implemented process. Thus, the instructions executed on the computer or other programmable device provide steps for realizing the functions specified in one Figure 1 flow or multiple flows and / or blocks Figure 1 block or multiple blocks.

[0041] The above are only the embodiments of the present invention and are not used to limit the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present invention are included within the scope of the claims of the present invention pending approval.

Claims

1. A boost inverter cascaded converter for suppressing the common-mode DC component, characterized in that, the boost inverter cascaded converter includes: a DC-DC converter, a three-phase inverter, and an LC filter; the midpoint of the capacitor bridge arm of the three-phase inverter is connected in series with an inductor and connected to the external aircraft metal structure; the common terminal of the filter capacitor of the LC filter is led out as the neutral point N of the three-phase inverter and connected to the negative line of the low-voltage input side of the DC-DC converter; the midpoint of the capacitor bridge arm of the three-phase inverter is connected to the neutral line of the three-phase inverter and the negative line of the low-voltage input side of the DC-DC converter through a series-connected inductor.

2. The airborne cascaded power converter according to claim 1, characterized in that, the potential of the midpoint of the capacitor bridge arm of the three-phase inverter is clamped.

3. The airborne cascaded power converter according to claim 1, characterized in that, the capacitor bridge arm of the three-phase inverter is connected in parallel on the input side of the three-phase inverter.

4. The airborne cascaded power converter according to claim 3, characterized in that, the three-phase inverter further includes a first bridge arm, a second bridge arm, and a third bridge arm, and the capacitor bridge arm, the first bridge arm, the second bridge arm, and the third bridge arm of the three-phase inverter are connected in parallel in sequence.

5. A method for suppressing the common-mode DC component using any one of the boost inverter cascaded converters as claimed in claims 1-4, the method comprises: clamping the potential of the midpoint of the capacitor bridge arm of the three-phase inverter.

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