Airborne high-voltage direct-current conversion device of unmanned aerial vehicle

Abstract

The utility model discloses an unmanned aerial vehicle airborne high-voltage DC conversion device, and the device comprises an input filtering module which filters noise and is connected with an external power supply; a plurality of first DC / DC modules, the plurality of first DC / DC modules are arranged in parallel, the first DC / DC modules are connected with the input filtering module, and the first DC / DC modules reduce the voltage of an external power supply; and the output control module is connected with a CAN (Controller Area Network) bus and the plurality of first DC / DC modules, and the output control module sends a signal according to the CAN bus to control the work of the plurality of first DC / DC modules.

Description

Technical Field

[0001] This application belongs to the field of tethered drones, and particularly relates to an airborne high-voltage DC converter. Background Art

[0002] With the continuous improvement of the power level of tethered drones, the power and stability of the input power supply are also constantly increasing. In particular, the power converter also places increasingly high requirements on the voltage and current stresses of power devices. In order to reduce the stress requirements on devices, the traditional method uses an interleaved parallel Buck circuit, and the traditional interleaved parallel Buck circuit usually consists of two-phase or multi-phase parallel Buck converters. Among them, the MOS transistors of each converter are turned on alternately, that is, the turn-on moments within the switching cycle are sequentially delayed by a certain time, so that the current flowing through each converter also shows an interleaved state. Through the interleaved operation technology, the load current is dispersed to multiple phases, reducing the ripple of the input and output currents, improving the thermal performance, and increasing the overall efficiency of the converter, and enhancing the power level of the circuit. However, the interleaved parallel Buck circuit has problems of current sharing and reliability in operation. Usually, voltage outer loop and current inner loop control are required to achieve balanced two-way current, which will lead to a complex control circuit and increase the cost of the control circuit. Summary of the Utility Model

[0003] To solve the above problems, the purpose of this application is to provide an airborne high-voltage DC conversion device for drones with better current distribution and improved efficiency.

[0004] An embodiment of this application provides an airborne high-voltage DC conversion device for drones, including:

[0005] An input filtering module, which filters noise and is connected to an external power supply;

[0006] A first DC / DC module, multiple of which are provided and are connected in parallel. The first DC / DC module is connected to the input filtering module, and the first DC / DC module steps down the external power supply;

[0007] An output control module, which is connected to the CAN bus and multiple first DC / DC modules, and the output control module controls the operation of multiple first DC / DC modules according to the signals sent by the CAN bus.

[0008] Further, for the above-mentioned airborne high-voltage DC conversion device for drones, the first DC / DC module includes:

[0009] A soft-start circuit, which limits the inrush current. The soft-start circuit includes:

[0010] A first buffer resistor that limits inrush current and is connected to the positive input terminal of the soft-start circuit;

[0011] A contactor that is connected in parallel with the first buffer resistor;

[0012] A fuse that is connected in series with the contactor;

[0013] An input EMI circuit that is connected to the soft-start circuit and filters out high-frequency interference signals;

[0014] A buck circuit that includes at least two stages of interleaved buck converters and is connected to the input EMI circuit;

[0015] A reverse-current prevention diode whose input terminal is connected to the positive output terminal of the buck circuit to prevent reverse current;

[0016] A capacitor whose positive electrode is connected to the negative electrode of the reverse-current prevention diode, and whose negative electrode is connected to the negative output terminal of the buck circuit, for filtering and smoothing the voltage;

[0017] An output EMI circuit that reduces output noise, with its positive input terminal connected to the positive electrode of the capacitor and its negative input terminal connected to the negative output terminal of the buck circuit;

[0018] A discharge circuit that is connected to the output EMI circuit and discharges the capacitor.

[0019] Furthermore, for the above-mentioned airborne high-voltage DC conversion device of the unmanned aerial vehicle, the buck converter includes a converter switching device, a converter inductor, and a converter diode. The converter switching device and the converter inductor are connected in series to the positive input terminal of the buck circuit, the positive electrode of the converter diode is connected to the negative input terminal of the buck circuit, and the negative electrode of the converter diode is connected to the converter diode.

[0020] Furthermore, for the above-mentioned airborne high-voltage DC conversion device of the unmanned aerial vehicle, the converter switching device is a MOS transistor.

[0021] Furthermore, for the above-mentioned airborne high-voltage DC conversion device of the unmanned aerial vehicle, the discharge circuit is a resistor.

[0022] Further, for the airborne high-voltage DC conversion device of the drone, the discharge circuit includes a first discharge resistor and a second discharge resistor. The first discharge resistor and the second discharge resistor are connected in series. One end of the first discharge resistor is connected to the positive output terminal of the output EMI circuit, and one end of the second discharge resistor is connected to the negative output terminal of the output EMI circuit.

[0023] Further, for the airborne high-voltage DC conversion device of the drone, the input EMI circuit includes an input EMI inductor and an input EMI capacitor.

[0024] Further, for the airborne high-voltage DC conversion device of the drone, the output EMI circuit includes an output EMI inductor and an output EMI capacitor.

[0025] Further, the airborne high-voltage DC conversion device of the drone further includes a second DC / DC module, and the second DC / DC module is a 48V / 1kW DC / DC module.

[0026] The technical solution provided by the embodiment of the present application has the following advantages:

[0027] (1) Since a soft-start circuit is adopted, this circuit gradually charges the capacitor through a resistor to limit the inrush current during startup and protect the subsequent circuit components. Until the voltage reaches the set level, the contactor K1 closes, bypassing the resistor to complete the soft-start process;

[0028] (2) Since an input EMI circuit is used, a low-pass filter composed of an inductor and a capacitor is used to attenuate high-frequency noise, improve electromagnetic compatibility, and reduce the interference of the high-voltage DC power supply to the input power supply.

[0029] (3) Since a buck circuit is adopted, an interleaved Buck converter is used to minimize the output current ripple by alternately turning on the switching tubes, improve efficiency, reduce the stress of components. The interleaved parallel method not only improves the device expansion ability but also improves the system output ripple characteristics and dynamic response;

[0030] (4) Since an output EMI circuit is adopted, the noise at the output end can be reduced to ensure a cleaner power output;

[0031] (5) Since an anti-backflow diode is adopted, the problem of reduced efficiency caused by output circulating current and damage to power devices leading to module failure can be effectively solved;

[0032] (6) Since a discharge circuit is adopted, it ensures the safe discharge of the capacitor after the power supply is turned off, preventing the residual voltage from causing harm to people or equipment;

[0033] (7) Since the output control module is adopted to trigger and control each module, it can effectively control the output voltages of each module to be consistent, achieve an increase in the power density of the module, save the cost of the control circuit at the same time, and the buck circuit 3 can automatically equalize the current and reduce heat generation. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] The drawings forming a part of this application are used to provide a further understanding of the present invention. The schematic embodiments and descriptions thereof of the present invention are used to explain the present invention and do not constitute an improper limitation to the present invention.

[0035] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the following will briefly introduce the drawings required for the description of the embodiments. Obviously, the drawings in the following description are only some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can be obtained based on these drawings.

[0036] In addition, the drawings are not drawn to a scale of 1:1, and the relative sizes of the respective elements are only drawn exemplarily in the drawings and not necessarily drawn according to the actual scale. In the drawings:

[0037] Figure 1 is a block diagram of a preferred airborne high-voltage DC conversion device for an unmanned aerial vehicle in an embodiment of the present utility model;

[0038] Figure 2 is a topological circuit diagram of a first DC / DC module in a preferred embodiment of the present utility model. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0039] To make the purposes, technical solutions and advantages of the implementation of this application clearer, the following will describe the technical solutions in the embodiments of this application in more detail with reference to the drawings in the embodiments of this application. In the drawings, the same or similar reference numerals denote the same or similar elements or elements with the same or similar functions. The described embodiments are some but not all of the embodiments of this application. The embodiments described below by referring to the drawings are exemplary and are intended to explain this application and should not be construed as a limitation to this application. Based on the embodiments in this application, all other embodiments obtained by those of ordinary skill in the art without creative efforts fall within the scope of protection of this application.

[0040] In addition, it should be noted that, unless otherwise clearly specified and limited, the similar terms such as "installed", "connected", and "linked" used in the description of this application should be understood in a broad sense. For example, the connection can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium, and it can also be the communication inside two components. Those skilled in the art can understand its specific meaning in this application according to the specific situation.

[0041] Figure 1 This is a block diagram of a preferred airborne high-voltage DC conversion device for an embodiment of the present utility model. As Figure 1 shown, the airborne high-voltage DC conversion device of the drone includes: an input filter module A, which filters noise, and the input filter module A is connected to an external power supply. A first DC / DC module B, multiple first DC / DC modules B are provided, and the multiple first DC / DC modules B are arranged in parallel. The first DC / DC module is connected to the input filter module, and the first DC / DC module steps down the external power supply. An output control module C, which is connected to the CAN bus and multiple first DC / DC modules. The output control module C controls the operation of the multiple first DC / DC modules according to the signals sent by the CAN bus. Preferably, the output control module C may further include an auxiliary power supply D, and the auxiliary power supply D provides additional power supply for the output control module C. A second DC / DC module E, in this embodiment, the second DC / DC module E is a 48V / 1kW DC / DC module.

[0042] Figure 2 This is a topological circuit diagram of a preferred first DC / DC module for an embodiment of the present utility model. As Figure 2 shown, the first DC / DC module B includes: a soft-start circuit 1, which limits the inrush current. The soft-start circuit 1 includes: a first buffer resistor R1, which limits the inrush current, and the first buffer resistor R1 is connected to the positive input terminal of the soft-start circuit 1. A contactor K1, which is connected in parallel with the first buffer resistor R1; a fuse F1, which is connected in series with the contactor K1.

[0043] Specifically, the principle of the soft-start circuit 1 is to input high-voltage direct current, charge the subsequent capacitor C1 after current limiting through the first buffer resistor R1. When the detection circuit detects that the voltage rises to the set threshold, the contactor K1 conducts, short-circuiting the buffer resistor. The purpose of the soft start is to limit the inrush current when power is just turned on.

[0044] Input EMI (Electro Magnetic Interference) circuit 2 is connected to the soft-start circuit 1. The input EMI circuit 2 filters out high-frequency interference signals. The input EMI circuit includes an input EMI inductor and an input EMI capacitor.

[0045] Specifically, the input EMI circuit 2 is a low-pass filter composed of an input EMI inductor and an input EMI capacitor. It allows DC or low-frequency signals to pass through and has a large attenuation effect on other signals and interference signals with higher frequencies. Since there are two types of interference signals, differential mode and common mode, the power filter is required to have a good attenuation effect on both types of interference. The filter is essentially an LC passive network. It uses the principle of impedance mismatch to attenuate electromagnetic interference signals. The filtering effect of the filter depends on the degree of impedance mismatch. The greater the impedance difference, the better the filtering effect. To meet the electromagnetic compatibility requirements of the high-voltage DC power supply and reduce the mutual influence between the input source and the high-voltage DC power supply, a common-mode filtering circuit is added at the input end of the high-voltage DC power supply.

[0046] Step-down circuit 3, the step-down circuit 3 includes at least two stages of interleaved parallel buck converters 31, and the step-down circuit 3 is connected to the input EMI circuit 2.

[0047] Preferably, the buck converter 31 includes converter switch devices Q1, Q2, converter inductors L1, L2, and converter diodes D1, D2. The converter switch devices Q1, Q2 and the converter inductors L1, L2 are connected in series to the positive input terminal of the step-down circuit. The positive electrodes of the converter diodes D1, D2 are connected to the negative input terminal of the step-down circuit 3, and the negative electrodes of the converter diodes D1, D2 are connected to the converter diodes.

[0048] Specifically, the step-down circuit 3 mainly uses two buck converters 31 to form a two-stage interleaved parallel buck converter. The conduction time of the switch tubes is controlled in turn, so that the conduction time of one switch tube lags behind the conduction time of the other switch tube by T / 2. In this way, the output currents of the two-stage buck converters 31 can be interleaved and superimposed, and the total output current ripple synthesized by the superposition of the current peaks and current valleys is relatively small. At the same time, the current harmonic frequency is twice that of the output ripple of a single-stage buck converter 31, so the pulsation amplitude of the output current is greatly reduced compared with that of a single-stage buck converter 31. For the interleaved parallel connection of the inductor currents flowing through the two-stage buck converters 31, the total output ripple current of the interleaved parallel connection is equivalent to twice the switching frequency. The ripple current of the converter inductor 312 is filtered by the output capacitor C1. The increase in the ripple current frequency reduces the capacitance, and at the same time, the volume and weight of the step-down circuit 3 are reduced. The input current waveform is improved, the power factor of the whole converter is increased, and the system efficiency and power density are improved.

[0049] The anti-backflow diode 4, the input end of the anti-backflow diode 4 is connected to the positive output end of the buck circuit 3, and the anti-backflow diode 4 prevents current backflow.

[0050] The capacitor C1, the positive electrode of the capacitor C1 is connected to the negative electrode of the anti-leakage diode 4, and the negative electrode of the capacitor C1 is connected to the negative output end of the buck circuit 3. The capacitor C1 filters and smooths the voltage.

[0051] The output EMI circuit 5, the output EMI circuit 5 reduces the output noise. The positive input end of the output EMI circuit 5 is connected to the positive electrode of the capacitor C1, and the negative input end of the output EMI circuit 5 is connected to the negative output end of the buck circuit 3. The output EMI circuit includes an output EMI inductor and an output EMI capacitor.

[0052] Specifically, the spike voltage generated by the buck circuit 3 is a narrow pulse with a large amplitude. Setting the output EMI circuit 5 can meet the electromagnetic compatibility requirements of the airborne high-voltage DC conversion device for drones and reduce the mutual influence between the power supply and the output load.

[0053] The discharge circuit 6, the discharge circuit 6 is connected to the output EMI circuit 5, and the discharge circuit 6 discharges the capacitor C1. The discharge of the capacitor C1 is very important because even if the power supply is turned off, the charged capacitor C1 can still cause an impact to anyone.

[0054] Preferably, the discharge circuit 6 is a resistor. The discharge circuit 6 includes a first discharge resistor R2 and a second discharge resistor R3. The first discharge resistor R2 and the second discharge resistor R3 are connected in series. One end of the first discharge resistor R2 is connected to the positive output end of the output EMI circuit 5, and one end of the second discharge resistor R3 is connected to the negative output end of the output EMI circuit 5.

[0055] As Figures 1 - 2 shown, in this preferred embodiment, the input DC of 800V - 1300V is filtered by the input filter module A and then sent to 5 first DC / DC modules B and the auxiliary power supply D respectively. The auxiliary power supply D outputs 12V to supply power to the output control. The external host computer sends a startup output instruction through the CAN interface, and the output control module C sends control signals to each module uniformly. In this embodiment, the converter switch device is a MOS transistor. The CAN interface controls the alternate conduction and cutoff of the contactor K1 and the MOS transistor to control the current in each converter inductor 311. Multiple first DC / DC modules B work simultaneously to output 360V (the power of each DC / DC module is 6kW), and the parallel output is 30kW for the rear-end drone drive motor. At the same time, the second DC / DC module E provides an electrical output of 48V / 1kW, and 48V can be reserved for power supply to the communication base station.

[0056] The airborne high-voltage DC conversion device of the present application can accept a power input range of 800V to 1300V, effectively solving problems such as the load of tethered drones. After testing, the ripple characteristics of the first DC / DC module B can achieve <0.2% FS, the dynamic response time is within 1ms, and the voltage gain is 0.5 times that of traditional Buck or interleaved Buck converters. The voltage stress of the converter switch device and the converter diode is half of the input voltage, that is, half of the traditional Buck converter; the output current ripple is 0.5(1 - 2D) / (1 - D) times that of the traditional Buck converter and 0.5 times that of the traditional interleaved buck converter, with smaller ripple and a frequency of 2 times.

[0057] The present application has at least the following beneficial effects:

[0058] (1) Due to the adoption of the soft-start circuit 1, this circuit gradually charges the capacitor through a resistor, limits the inrush current during startup, protects subsequent circuit components, and until the voltage reaches the set level, the contactor K1 closes, bypassing the resistor to complete the soft-start process;

[0059] (2) Due to the use of the input EMI circuit 2, a low-pass filter composed of an inductor and a capacitor, which is used to attenuate high-frequency noise, improve electromagnetic compatibility, and reduce the interference of the high-voltage DC power supply to the input power supply.

[0060] (3) Due to the adoption of the buck circuit 3, an interleaved parallel Buck converter is used to minimize the output current ripple by alternately turning on the switching tubes, improve efficiency, reduce the stress of components. The interleaved parallel method not only improves the device expandability but also improves the system output ripple characteristics and dynamic response;

[0061] (4) Due to the adoption of the output EMI circuit 5, the noise at the output end can be reduced to ensure a cleaner power output;

[0062] (5) Due to the adoption of the anti-backflow diode 4, it effectively solves the problems of reduced efficiency caused by output circulating current and damage to power devices, resulting in module failure;

[0063] (6) Due to the adoption of the discharge circuit 6, it ensures the safe discharge of the capacitor after the power supply is turned off, preventing the residual voltage from causing harm to people or equipment;

[0064] (7) Due to the adoption of the output control module to trigger and control each module, it can effectively control the output voltages of each module to be consistent, realize an increase in the module power density, save the cost of the control circuit at the same time, and the buck circuit 3 can automatically balance the current and reduce heat generation.

[0065] The above embodiments are provided for those skilled in the art to implement or use the present application. Those skilled in the art can make various modifications or changes to the above embodiments without departing from the application idea of the present application. Therefore, the protection scope of the present application is not limited by the above embodiments, but should be the maximum scope that conforms to the innovative features mentioned in the claims.

Claims

1. An airborne high-voltage DC conversion device for an unmanned aerial vehicle, characterized in that, Comprising: An input filtering module that filters noise and is connected to an external power supply; A first DC / DC module, with multiple of said first DC / DC modules arranged in parallel. The first DC / DC module is connected to the input filtering module and steps down the external power supply; An output control module that is connected to the CAN bus and multiple of said first DC / DC modules, and controls the operation of multiple first DC / DC modules according to signals sent by the CAN bus.

2. The airborne high-voltage DC conversion device for a drone according to claim 1, wherein The first DC / DC module includes: A soft-start circuit that limits inrush current. The soft-start circuit includes: A first buffer resistor that limits inrush current and is connected to the positive input terminal of the soft-start circuit; A contactor that is connected in parallel with the first buffer resistor; A fuse that is connected in series with the contactor; An input EMI circuit that is connected to the soft-start circuit and filters out high-frequency interference signals; A bucking circuit that includes at least two stages of interleaved and parallel buck converters and is connected to the input EMI circuit; An anti-backflow diode, whose input terminal is connected to the positive output terminal of the bucking circuit to prevent current backflow; A capacitor, whose positive terminal is connected to the negative terminal of the anti-backflow diode, and whose negative terminal is connected to the negative output terminal of the bucking circuit. The capacitor filters and smooths the voltage; An output EMI circuit that reduces output noise. The positive input terminal of the output EMI circuit is connected to the positive terminal of the capacitor, and the negative input terminal of the output EMI circuit is connected to the negative output terminal of the bucking circuit; A discharging circuit that is connected to the output EMI circuit and discharges the capacitor.

3. The airborne high-voltage DC conversion device for a drone according to claim 2, characterized in that, The buck converter includes a converter switching device, a converter inductor, and a converter diode. The converter switching device and the converter inductor are connected in series to the positive input terminal of the bucking circuit, the positive terminal of the converter diode is connected to the negative input terminal of the bucking circuit, and the negative terminal of the converter diode is connected to the converter diode.

4. The airborne high-voltage DC conversion device for a drone according to claim 3, wherein The converter switching device is a MOS transistor.

5. The airborne high-voltage DC conversion device for a drone according to claim 2, characterized in that, The discharging circuit is a resistor.

6. The airborne high-voltage DC conversion device for a drone according to claim 2, wherein The discharging circuit includes a first discharging resistor and a second discharging resistor. The first discharging resistor and the second discharging resistor are connected in series. One end of the first discharging resistor is connected to the positive output terminal of the output EMI circuit, and one end of the second discharging resistor is connected to the negative output terminal of the output EMI circuit.

7. The airborne high-voltage DC conversion device for a drone according to claim 2, characterized in that, The input EMI circuit includes an input EMI inductor and an input EMI capacitor.

8. The airborne high-voltage DC conversion device for a drone according to claim 2, wherein, The output EMI circuit includes an output EMI inductor and an output EMI capacitor.

9. The airborne high-voltage DC conversion device for a drone according to claim 1, characterized in that, It further includes a second DC / DC module, which is a 48V / 1kW DC / DC module.

Images