An airborne cascaded power converter and method for suppressing common-mode DC voltage

Abstract

The present invention proposes an airborne cascaded power converter and method for suppressing common-mode DC voltage, belonging to the technical field of aircraft airborne power supplies. The airborne cascaded power converter of the present invention includes: a DC-DC converter, a three-phase inverter, and an LC filter; the midpoint of the resistor bridge arm of the three-phase inverter is connected to the negative line of the low-voltage input side of the DC-DC converter through the neutral line of the three-phase inverter; 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; the midpoint of the resistor bridge arm of the LC filter 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. The present invention is suitable for application in the aircraft secondary power supply system with single-point grounding; and it has low cost and simple structure, without adding 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 an on-board cascaded power converter and method for suppressing common-mode DC voltage. Background Art

[0002] Considering the diversity of load types, aircraft power supply systems usually have multiple power supply systems, for example, Boeing B787 has both 28V DC and 115V AC power supply forms.

[0003] In the case of the loss of power on the AC busbar, it is necessary to convert 28V DC into 115V AC through advanced power electronic devices. This power conversion usually adopts a cascaded conversion topology of DC-DC and DC-AC. Considering factors such as power density, transmission efficiency, and safety, the front-stage boost circuit mostly adopts an isolated full-bridge DC-DC converter, and the rear-stage inverter circuit mostly adopts a three-phase bridge DC-AC inverter circuit.

[0004] Different from the structure of the ground power supply system, the aircraft power supply system is grounded at a single point. According to industry general standard specifications such as AC43.13-1B, ARP1870, and GJB181A-2012, the current return path of the aircraft electrical circuit includes the AC and DC power grounds, and both are connected to the aircraft metal structure, as Figure 1 shown. Although this solution 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 circuit of the neutral line of the AC output and the negative line of the DC input of the DC-DC converter, under the influence of the distributed capacitance of the primary and secondary windings of the transformer, makes the cascaded system have a common-mode interference conduction path, 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 extremely.

[0005] The prior art usually suppresses the common-mode voltage by increasing the fundamental frequency transformer or auxiliary 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 an on-board cascaded power converter for suppressing common-mode DC voltage, including: a DC-DC converter, a three-phase inverter, and an LC filter;

[0007] The midpoint of the resistor bridge arm of the three-phase inverter is connected to the negative line of the low-voltage input side of the DC-DC converter through the neutral line of the three-phase inverter;

[0008] The common end 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 resistor bridge arm of the LC filter 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.

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

[0011] Optionally, the resistor bridge arm of the three-phase inverter is connected in parallel on the input side of the three-phase inverter.

[0012] Optionally, the three-phase inverter further includes a first bridge arm, a second bridge arm, and a third bridge arm, and the resistor 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.

[0013] On the other hand, the present invention also proposes a method for suppressing the common-mode DC voltage using the above airborne cascaded power converter, including: clamping the potential of the midpoint of the resistor bridge arm of the three-phase inverter.

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

[0015] In the present invention, the midpoint of the resistor 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; the common end 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; the midpoint of the resistor bridge arm of the LC filter 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; the present invention is suitable for application in the aircraft secondary power system with single-point grounding; and it has low cost and simple structure, without adding any complex active circuits or software algorithms, and can effectively improve the power density of the converter. In addition, the present invention is not affected by the topology of the 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 It is a schematic structural diagram of the cascaded converter of the present invention in an aircraft environment;

[0017] Figure 2 It is a schematic structural diagram of an airborne cascaded power converter for suppressing common-mode DC voltage according to the present invention. Detailed Embodiments

[0018] Now, the exemplary embodiments of the present invention will be introduced with reference to the 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 limitations to the present invention. In the drawings, the same units / components are denoted by the same reference numerals.

[0019] Unless otherwise specified, the terms used herein (including technical terms) have the ordinary meaning 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 a meaning consistent with the context of their relevant fields and should not be construed as having an idealized or overly formal meaning.

[0020] The present invention provides an airborne cascaded power converter for suppressing common-mode DC voltage, such as Figure 2 shown, including: a DC-DC converter, a three-phase inverter, and an LC filter;

[0021] The midpoint of the resistive bridge arm of the three-phase inverter is connected to the negative line of the low-voltage input side of the DC-DC converter through the neutral line of the three-phase inverter.

[0022] 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.

[0023] The midpoint of the resistive bridge arm of the LC filter 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.

[0024] Wherein, the potential of the midpoint of the resistive bridge arm of the three-phase inverter is clamped.

[0025] The resistive bridge arms of the three-phase inverter are 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 resistive 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] Wherein, 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. The full-bridge inverter circuit includes a first bridge arm and a second bridge arm connected in parallel, the first bridge arm includes a MOS transistor Q1_1 and a MOS transistor Q1_2 connected in series, and the second bridge arm includes a MOS transistor Q1_3 and a MOS transistor 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 is in 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 resistive bridge arm, a first bridge arm, a second bridge arm, and a third bridge arm connected in parallel phases. The resistive bridge arm includes a first resistor R1 and a second resistor R2 connected in series. The first bridge arm includes a MOS transistor Q2_1 and a MOS transistor Q2_2 connected in series. The second bridge arm includes a MOS transistor Q2_3 and a MOS transistor Q2_4 connected in series. The third bridge arm includes a MOS transistor Q2_5 and a MOS transistor Q2_6 connected in series.

[0029] The conduction path of the common-mode interference in the present invention 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 of the primary and secondary windings of the DC-DC converter, the resonant cavity, and the rectifier bridge arm, and rectified to generate a common-mode DC voltage, which is superimposed on the sinusoidal voltage output by the inverter.

[0030] Among them, the DC-DC converter is not limited to the isolated LLC converter. For any airborne cascaded power converter with an isolated DC-DC converter at the front stage and a three-phase bridge inverter at the rear stage, the suppression of the common-mode DC voltage can be achieved.

[0031] The midpoint of the resistive bridge arm of the three-phase inverter in the present invention 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; 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 resistive bridge arm of the LC filter 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; it is suitable for application in the secondary power supply system of an aircraft with single-point grounding; and it has low cost and simple structure, without adding any complex active circuits or software algorithms, can effectively improve the power density of the converter. In addition, the present invention is not affected by the topology of the DC-DC converter and the parasitic parameters of the isolation transformer, and can ensure the reliable and stable operation of the cascaded converter.

[0032] Based on the same inventive concept, the present invention also provides a method for suppressing the common-mode DC voltage using the above-mentioned airborne cascaded power converter, including: clamping the potential of the midpoint of the resistive bridge arm of the three-phase inverter.

[0033] The method proposed in the present invention is to connect a resistive bridge arm in parallel on the input side of the three-phase inverter, and connect the midpoint of the resistive bridge arm to the neutral line of the three-phase inverter and the negative line of the low-voltage input side of the DC-DC converter at the same time, clamp the potential of the midpoint of the resistive bridge arm, and realize the suppression of the common-mode DC component of the AC output voltage.

[0034] The method proposed in the present invention is applied for the first time in the working condition of the aircraft power supply system.

[0035] 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.

[0036] The present invention is described with reference to the flowcharts and / or block diagrams of methods, apparatuses (systems), and computer program products according to embodiments of the present invention. It should be understood that each flow and / or block in the flowchart and / or block diagram, and the combination of flows and / or blocks in the flowchart and / or block diagram, 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 Figure 1 one flow or multiple flows and / or blocks Figure 1 one block or multiple blocks.

[0037] These computer program instructions can also be stored in a computer-readable memory that can direct a computer or other programmable data processing devices 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 Figure 1 one flow or multiple flows and / or blocks Figure 1 one block or multiple blocks.

[0038] These computer program instructions can also be loaded onto a computer or other programmable data processing devices, so that a series of operation steps are executed on the computer or other programmable devices to generate a computer-implemented process, and thus the instructions executed on the computer or other programmable devices provide steps for realizing the functions specified in Figure 1 one flow or multiple flows and / or blocks Figure 1 one block or multiple blocks.

[0039] The above are only 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 principle of the present invention are included in the scope of the claims of the present invention pending approval.

Claims

1. An airborne cascaded power converter for suppressing common-mode DC voltage, characterized in that The airborne cascaded power converter includes: a DC-DC converter, a three-phase inverter, and an LC filter; The midpoint of the resistive bridge arm of the three-phase inverter is connected to the negative line of the low-voltage input side of the DC-DC converter through the neutral line of the three-phase inverter; the resistive bridge arm of the three-phase inverter is connected in parallel on the input side of the three-phase inverter; the three-phase inverter further includes a first bridge arm, a second bridge arm, and a third bridge arm, and the resistive 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; The common end 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; The midpoint of the resistive bridge arm of the LC filter 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.

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

3. A method for suppressing common-mode DC voltage using any one of the airborne cascade power converters described in claims 1-2, the method comprising: Clamp the potential of the midpoint of the resistive bridge arm of the three-phase inverter.

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