Unmanned aerial vehicle energy supply system and unmanned aerial vehicle

Abstract

The invention discloses an unmanned aerial vehicle energy supply system and an unmanned aerial vehicle. The unmanned aerial vehicle energy supply system comprises a transmitting end used for converting direct-current electric energy into alternating-current electric energy and transmitting the alternating-current electric energy through magnetic field coupling; the receiving end is used for receiving the AC electric energy and converting the AC electric energy into DC to charge a battery; wherein the transmitting end comprises a direct current-alternating current inversion structure which is supplied with power by an input direct current voltage source and is used for generating alternating current voltage; the transmitting end resonance structure is connected to the output end of the direct current-alternating current inversion structure; the auxiliary clamping loop is connected with the transmitting end resonance structure; the receiving end comprises a receiving end resonance structure which is coupled with the transmitting end resonance structure through a magnetic field; and the passive rectification structure is connected with the receiving end resonance structure, and the output end is connected with a battery.

Description

Technical Field

[0001] This invention relates to the field of wireless power transfer technology for unmanned aerial vehicles (UAVs), and more specifically, to a UAV power supply system and a UAV. Background Technology

[0002] With the rapid development of technology, drones are increasingly widely and deeply applied in fields such as aerial photography, logistics, agricultural monitoring, and emergency rescue. Their endurance and lightweight requirements have become key factors restricting their further development. Traditional wired charging methods are not only limited by the length of the charging cable and interface standards, but also prone to wear and tear and poor contact due to frequent plugging and unplugging in complex outdoor environments or multi-drone collaborative operation scenarios, greatly affecting charging efficiency and the ease of use of drones. Against this backdrop, combining wireless power transmission technology with lithium-ion battery charging technology to create a wireless charging solution for drones can effectively solve many of the inconveniences of wired charging technology, greatly improving the freedom and flexibility of charging and providing strong support for the continuous and efficient operation of drones. Currently, researchers have proposed various methods to achieve constant current-constant voltage mode switching during battery charging, which can be mainly divided into the following categories: real-time closed-loop strategy control, reconfigurable topology switching, high-order network frequency hopping, and front-end clamping auxiliary circuits. However, these types of constant current to constant voltage switching required for battery charging still face several challenges, including battery status monitoring, wireless communication requirements between primary and secondary sides, and cross-coupling issues in multi-coil systems. These problems result in larger drone sizes, making it impossible to achieve the lightweight requirement. Summary of the Invention

[0003] To address the shortcomings of existing technologies, this invention provides a drone energy replenishment system and a drone.

[0004] According to one aspect of the present invention, a drone energy replenishment system is provided, comprising:

[0005] The transmitter is used to convert DC power into AC power and transmit it via magnetic field coupling;

[0006] The receiving end is used to receive AC power and convert it into DC power to charge the battery.

[0007] The transmitting end includes:

[0008] The DC-AC inverter structure is powered by an input DC voltage source and is used to generate AC voltage.

[0009] The transmitter resonant structure is connected to the output of the DC-AC inverter structure;

[0010] An auxiliary clamping circuit is connected to the transmitter resonant structure.

[0011] The receiving end includes:

[0012] The receiver resonant structure is coupled to the transmitter resonant structure via a magnetic field.

[0013] The passive rectifier structure is connected to the receiving end resonant structure, and its output end is used to connect to the battery.

[0014] Optionally, the circuit parameters of the UAV energy replenishment system are configured as follows: in the initial stage of battery charging, the auxiliary clamping circuit does not work, and the system is equivalent to the SS compensation topology to achieve constant current output to the battery; as the equivalent load of the battery increases, the auxiliary clamping circuit automatically intervenes to work, so that the system switches to constant voltage output to the battery, realizing constant current-constant voltage automatic switching without additional control strategies.

[0015] Optionally, the DC-AC inverter structure is a half-bridge inverter, which includes a first switching transistor and a second switching transistor.

[0016] Optionally, the transmitter may also include an input filter capacitor connected in parallel across the input DC voltage source.

[0017] Optionally, the transmitter resonant structure includes a transmitter coil and a first resonant capacitor connected in series.

[0018] Optionally, the auxiliary clamping circuit includes a first clamping diode, a second clamping diode, a clamping capacitor, and a clamping inductor;

[0019] In this configuration, the cathode of the first clamping diode is connected to the drain of the first switching transistor, and its anode is connected to the cathode of the second clamping diode and one end of the clamping capacitor.

[0020] The anode of the second clamping diode is connected to the source of the second switching transistor and one end of the clamping inductor;

[0021] The other end of the clamping capacitor is connected to the other end of the clamping inductor and the common connection point of the transmitting coil and the first resonant capacitor.

[0022] Optionally, the component parameters of the transmitter resonant structure and the transmitter auxiliary clamping circuit satisfy the following resonance relationship:

[0023]

[0024] Where ω is the operating angular frequency of the system.

[0025] Optionally, the receiver resonant structure is a series-compensated topology, including a receiving coil and a second resonant capacitor, with the receiving coil and the second resonant capacitor connected in series, satisfying the following relationship:

[0026]

[0027] Where ω is the operating angular frequency of the system.

[0028] Optionally, the passive rectification structure is a full-bridge passive rectifier, which consists of a first rectifier diode, a second rectifier diode, a third rectifier diode and a fourth rectifier diode, and is connected to an output filter capacitor;

[0029] One end of the receiving coil is connected to the second resonant capacitor, and the other end is connected to the anode of the first rectifier diode and the cathode of the second rectifier diode.

[0030] One end of the second resonant capacitor is connected to the receiving coil, the anode of the third rectifier diode, and the cathode of the fourth rectifier diode.

[0031] The output filter capacitor is connected in parallel across the two ends of the passive rectifier structure. One end is connected to the cathodes of the first and third rectifier diodes, and the other end is connected to the cathodes of the second and fourth rectifier diodes.

[0032] Optionally, the DC-AC inverter structure satisfies the following relationship:

[0033] Optionally, during the constant current output phase of the UAV energy replenishment system, the system's output current I... b The expression is:

[0034]

[0035] Where ω is the system's operating angular frequency, M ps This represents the mutual inductance between the transmitting and receiving coils.

[0036] Optionally, the termination resistor R during the charging transition phase of the drone energy replenishment system L2 The expression is:

[0037] Alternatively, during the constant voltage output phase, the system's output voltage is determined by the following formula:

[0038]

[0039] Among them, L r The clamping inductor is used to assist in the clamping circuit.

[0040] According to another aspect of the present invention, a drone is provided, including the drone energy replenishment system described in any of the preceding aspects, for charging its onboard lithium-ion battery.

[0041] Therefore, this invention proposes a UAV energy replenishment system with inherent constant current and constant voltage conversion capabilities. This system, by adding an auxiliary clamping circuit to the primary topology, can complete the constant current and constant voltage conversion required for lithium-ion battery charging without any control strategy. In the initial charging stage, the auxiliary clamping circuit is closed, and the proposed charging system can be equivalent to an SS system, achieving a constant current output. As the charging process progresses, the equivalent resistance of the lithium-ion battery gradually increases, causing the auxiliary clamping circuit to gradually conduct. When conduction is complete, it signifies that the proposed charging system has entered the constant voltage stage. Due to the system's circuit parameter design, both the constant current and constant voltage processes achieve zero input impedance characteristics, and the switching transistor can be turned off at zero voltage, effectively improving system efficiency. Furthermore, the system has a two-coil structure, eliminating cross-coupling, allowing for greater spatial design freedom, and the receiving side uses only a series-type compensation topology, facilitating lightweight design on the receiving side. Attached Figure Description

[0042] Exemplary embodiments of the present invention can be more fully understood by referring to the following figures:

[0043] Figure 1 This is a schematic diagram of the structure of an unmanned aerial vehicle (UAV) energy replenishment system provided in an exemplary embodiment of the present invention;

[0044] Figure 2 This is a schematic diagram of the output characteristics of the system in constant current mode provided by an exemplary embodiment of the present invention;

[0045] Figure 3 This is a schematic diagram of the output characteristics of the system in constant voltage mode provided by an exemplary embodiment of the present invention. Detailed Implementation

[0046] Hereinafter, exemplary embodiments according to the present invention will be described in detail with reference to the accompanying drawings. Obviously, the described embodiments are merely some embodiments of the present invention, and not all embodiments of the present invention. It should be understood that the present invention is not limited to the exemplary embodiments described herein.

[0047] It should be noted that, unless otherwise specifically stated, the relative arrangement, numerical expressions, and values ​​of the components and steps described in these embodiments do not limit the scope of the invention.

[0048] Those skilled in the art will understand that the terms "first," "second," etc., in the embodiments of the present invention are only used to distinguish different steps, devices, or modules, and do not represent any specific technical meaning, nor do they indicate a necessary logical order between them.

[0049] It should also be understood that in the embodiments of the present invention, "multiple" can refer to two or more, and "at least one" can refer to one, two or more.

[0050] It should also be understood that any component, data or structure mentioned in the embodiments of the present invention can generally be understood as one or more unless explicitly defined or given contrary instructions in the context.

[0051] Furthermore, the term "and / or" in this invention is merely a description of the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent: A existing alone, A and B existing simultaneously, or B existing alone. Additionally, the character " / " in this invention generally indicates that the preceding and following related objects have an "or" relationship.

[0052] It should also be understood that the description of the various embodiments in this invention emphasizes the differences between the various embodiments, and the similarities or similarities can be referred to each other. For the sake of brevity, they will not be described in detail.

[0053] At the same time, it should be understood that, for ease of description, the dimensions of the various parts shown in the accompanying drawings are not drawn according to actual scale.

[0054] The following description of at least one exemplary embodiment is merely illustrative and is in no way intended to limit the invention or its application or use.

[0055] Techniques, methods, and equipment known to those skilled in the art may not be discussed in detail, but where appropriate, they should be considered part of the specification.

[0056] It should be noted that similar labels and letters in the following figures indicate similar items; therefore, once an item is defined in one figure, it does not need to be discussed further in subsequent figures.

[0057] Figure 1 This is a schematic diagram of the structure of the UAV energy replenishment system provided in the first aspect embodiment of the present invention. Figure 1 As shown, the drone energy replenishment system includes:

[0058] The transmitter is used to convert DC power into AC power and transmit it via magnetic field coupling;

[0059] The receiving end is used to receive AC power and convert it into DC power to charge the battery.

[0060] The transmitting end includes:

[0061] The DC-AC inverter structure consists of an input DC voltage source V dc Power supply, used to generate AC voltage V p ;

[0062] The transmitter resonant structure is connected to the output of the DC-AC inverter structure;

[0063] An auxiliary clamping circuit is connected to the transmitter resonant structure.

[0064] The receiving end includes:

[0065] The receiver resonant structure is coupled to the transmitter resonant structure via a magnetic field.

[0066] The passive rectifier structure is connected to the receiving end resonant structure, and its output end is used to connect to the battery.

[0067] Optionally, such as Figure 1 As shown, the circuit parameters of the UAV energy replenishment system are configured as follows: In the initial stage of battery charging, the auxiliary clamping circuit does not work, and the system is equivalent to the SS compensation topology, realizing constant current output to the battery; as the equivalent load of the battery increases, the auxiliary clamping circuit automatically intervenes and works, so that the system switches to constant voltage output to the battery, realizing constant current-constant voltage automatic switching without additional control strategies.

[0068] Optionally, such as Figure 1 As shown, the DC-AC inverter structure is a half-bridge inverter, which includes a first switch S1 and a second switch S2.

[0069] Among them, the first switch S1 and the second switch S2 are MOSFET switches.

[0070] Optionally, the transmitter also includes an input filter capacitor C. a Input filter capacitor C a Parallel connection to the input DC voltage source V dc The two ends.

[0071] Optionally, such as Figure 1 As shown, the transmitter resonant structure includes transmitter coils L connected in series. p and the first resonant capacitor C p .

[0072] Optionally, such as Figure 1 As shown, the auxiliary clamping circuit includes a first clamping diode D1, a second clamping diode D2, and a clamping capacitor C. r and clamping inductor L r ;

[0073] In this configuration, the cathode of the first clamping diode D1 is connected to the drain of the first switching transistor S1, and its anode is connected to the cathode of the second clamping diode D2 and the clamping capacitor C. r One end is connected;

[0074] The anode of the second clamping diode D2, the source of the second switching transistor S2, and the clamping inductor L rOne end is connected;

[0075] Clamping capacitor C r The other end is connected to the clamping inductor L r The other end and the transmitting coil L p and the first resonant capacitor C p They are connected to a common connection point.

[0076] Optionally, the component parameters of the transmitter resonant structure and the transmitter auxiliary clamping circuit satisfy the following resonance relationship:

[0077]

[0078] Where ω is the operating angular frequency of the system.

[0079] Optionally, the receiver resonant structure is a series-compensated topology, including a receiving coil L. s Second resonant capacitor C s Receiving coil L s With the second resonant capacitor C s A series connection satisfies the following relationship:

[0080]

[0081] Where ω is the operating angular frequency of the system.

[0082] Optionally, such as Figure 1 As shown, the passive rectification structure is a full-bridge passive rectifier, consisting of a first rectifier diode D3, a second rectifier diode D4, a third rectifier diode D5, and a fourth rectifier diode D6, and connected to an output filter capacitor C. b ;

[0083] Among them, the receiving coil L s One end and the second resonant capacitor C s One end is connected to the other end, which is connected to the anode of the first rectifier diode D3 and the cathode of the second rectifier diode D4;

[0084] Second resonant capacitor C s One end and receiving coil L s The anode of the third rectifier diode D5 and the cathode of the fourth rectifier diode D6 are connected.

[0085] Output filter capacitor C b It is connected in parallel at both ends of the passive rectifier structure. One end is connected to the cathode of the first rectifier diode D3 and the third rectifier diode D5, and the other end is connected to the cathode of the second rectifier diode D4 and the fourth rectifier diode D6.

[0086] Optionally, the DC-AC inverter structure satisfies the following relationship:

[0087] Optionally, during the constant current output phase of the UAV energy replenishment system, the system's output current I... b The expression is:

[0088]

[0089] Where ω is the system's operating angular frequency, M ps This represents the mutual inductance between the transmitting and receiving coils.

[0090] Optionally, the termination resistor R during the charging transition phase of the drone energy replenishment system L2 The expression is:

[0091] Optionally, during the constant voltage output phase, the system's output voltage V b It is determined by the following formula:

[0092]

[0093] Among them, L r The clamping inductor is used to assist in the clamping circuit.

[0094] Furthermore, according to another aspect of the present invention, a drone is provided, including the drone energy replenishment system described in any of the preceding aspects, for charging its onboard lithium-ion battery.

[0095] Specifically, existing wireless charging technologies for drones face several challenges, including battery status monitoring, the need for wireless communication between the primary and secondary windings, and cross-coupling issues in multi-coil systems. Front-end clamping auxiliary circuits have attracted widespread attention because they can achieve constant current and constant voltage switching during battery charging without any control strategy. However, this method still faces cross-coupling problems, leading to output fluctuations that may cause overvoltage damage to the battery.

[0096] Therefore, to address the cross-coupling problem inherent in multi-coil systems, this invention proposes a front-end clamping auxiliary circuit based on SS topology. The key advantage of this system is that it achieves the constant current-constant voltage conversion required for battery charging without any control strategy, while also avoiding the cross-coupling phenomenon common in multi-coil systems, resulting in a more stable system output.

[0097] The proposed front-end clamping auxiliary circuit based on SS topology is as follows: Figure 1 As shown. V dc This is a DC voltage source, Ca is the primary filter capacitor, S1 and S2 are a half-bridge inverter composed of MOSFETs, and D1 and D2 are clamping diodes. p C is the transmitting coil at the transmitting end of the proposed circuit.p C r L r As an impedance compensation element, the transmitting end resonant element satisfies formula (1). Ls is the secondary receiving coil, and its compensation element is capacitor C. s The resonance relationship is satisfied as shown in formula (2). Rectifier diodes D3, D4, D5, and D6 form a rectifier circuit, C b For the secondary filter capacitor, R L Let V be the internal resistance of the battery. The voltage across its terminals and the current flowing through it are respectively V. b and I b The output AC voltage of the half-bridge inverter is V. p The relationship between it and the input DC voltage is shown in formula (3).

[0098]

[0099] The key waveforms obtained are as follows Figure 2 and Figure 3 As shown, Figure 2 The system output characteristics in constant current mode are shown in the experimental waveforms. It can be clearly seen that the system can achieve constant current output when the battery load is between 5 ohms and 15 ohms. Figure 3 The system output characteristics in constant voltage mode are shown in the experimental waveforms. It can be clearly seen that the system can achieve constant voltage output when the battery load is between 25 ohms and 75 ohms.

[0100] 1. Implementation of constant current system

[0101] In the initial stage of charging, the auxiliary clamping circuit participates in the system operation. At this time, the system circuit structure can be approximately equivalent to the SS topology, so constant current output can be achieved. The expression for constant current output is as follows.

[0102]

[0103] 2. Charging transition process

[0104] As the charging process progresses, the peak voltage across the second clamping diode D1 can reach the amplitude V of the DC input voltage source. dc At this point, the relationship is as shown in (5).

[0105]

[0106] Since the system design parameters satisfy the resonance relationship shown in (1)(2)(3), the input equivalent impedance can be solved at this time.

[0107]

[0108] According to circuit theorem, current I pThe expression can be solved as follows.

[0109]

[0110] Combining (5), (6), and (7), the initial resistance of the transient process can be obtained.

[0111]

[0112] As the charging process proceeds, the voltage across the diode will be clamped into a square wave with an amplitude of V. dc The expression at this point is as follows.

[0113]

[0114] Similarly, the termination resistance of the transient process can be obtained.

[0115]

[0116] 3. Constant pressure process

[0117] When the transition process ends, the system enters the constant voltage process. Since the voltage across the first clamping diode D1 satisfies (9) at this time, the current I... p It will be clamped to a constant value.

[0118]

[0119] Therefore, the receiving side voltage V s It can remain constant, as shown in the following expression:

[0120]

[0121] Due to the output voltage V b From voltage V s The output voltage V is obtained after full-bridge rectification. b The expression is as follows:

[0122]

[0123] In summary, the proposed topology can realize the constant current and constant voltage process required for battery charging.

[0124] Therefore, this invention proposes a UAV energy replenishment system with inherent constant current and constant voltage conversion capabilities. This system, by adding an auxiliary clamping circuit to the primary topology, can complete the constant current and constant voltage conversion required for lithium-ion battery charging without any control strategy. In the initial charging stage, the auxiliary clamping circuit is closed, and the proposed charging system can be equivalent to an SS system, achieving a constant current output. As the charging process progresses, the equivalent resistance of the lithium-ion battery gradually increases, causing the auxiliary clamping circuit to gradually conduct. When conduction is complete, it signifies that the proposed charging system has entered the constant voltage stage.

[0125] Due to the system's circuit parameter design, zero input impedance characteristics can be achieved during both constant current and constant voltage processes, as well as zero-voltage turn-off of the switching transistor, effectively improving system efficiency. Furthermore, the system employs a two-coil structure, eliminating cross-coupling and allowing for greater spatial design freedom. The receiver side also features only a series-compensated topology, facilitating lightweight design on the receiver side.

[0126] The above description has been given for purposes of illustration and description. Furthermore, this description is not intended to limit the embodiments of the invention to the forms disclosed herein. Although numerous exemplary aspects and embodiments have been discussed above, those skilled in the art will recognize certain variations, modifications, alterations, additions, and sub-combinations thereof.

Claims

1. A drone energy replenishment system, characterized in that, include: The transmitter is used to convert DC power into AC power and transmit it via magnetic field coupling; The receiving end is used to receive the AC power and convert it into DC power to charge the battery; The transmitting end includes: The DC-AC inverter structure consists of an input DC voltage source (V... dc Power supply, used to generate AC voltage (V) p ); The transmitter resonant structure is connected to the output terminal of the DC-AC inverter structure; An auxiliary clamping circuit is connected to the transmitter resonant structure. The receiving end includes: The receiver resonant structure is coupled to the transmitter resonant structure via a magnetic field. A passive rectifier structure is connected to the receiving end resonant structure, and its output end is used to connect to the battery.

2. The UAV energy replenishment system according to claim 1, characterized in that, The circuit parameters of the UAV energy replenishment system are configured as follows: in the initial stage of battery charging, the auxiliary clamping circuit does not work, and the system is equivalent to an SS compensation topology to achieve constant current output to the battery; as the equivalent load of the battery increases, the auxiliary clamping circuit automatically intervenes to work, so that the system switches to constant voltage output to the battery, realizing constant current-constant voltage automatic switching without additional control strategies.

3. The UAV energy replenishment system according to claim 1, characterized in that, The DC-AC inverter structure is a half-bridge inverter, which includes a first switch (S1) and a second switch (S2).

4. The UAV energy replenishment system according to claim 3, characterized in that, The transmitter also includes an input filter capacitor (C). a The input filter capacitor (C) a ) connected in parallel to the input DC voltage source (V dc The two ends of ).

5. The UAV energy replenishment system according to claim 3, characterized in that, The transmitter resonant structure includes a transmitter coil (L) connected in series. p ) and the first resonant capacitor (C p ).

6. The UAV energy replenishment system according to claim 5, characterized in that, The auxiliary clamping circuit includes a first clamping diode (D1), a second clamping diode (D2), and a clamping capacitor (C). r ) and clamping inductor (L r ); In this configuration, the cathode of the first clamping diode (D1) is connected to the drain of the first switching transistor (S1), and its anode is connected to the cathode of the second clamping diode (D2) and the clamping capacitor (C). r Connect one end of the connector; The anode of the second clamping diode (D2) and the source of the second switching transistor (S2) and the clamping inductor (L) r Connect one end of the connector; The clamping capacitor (C) r The other end of the clamping inductor (L) is connected to the clamping inductor (L) r The other end of the transmitting coil (L) and the transmitting coil (L) p ) and the first resonant capacitor (C p The common connection points are connected.

7. The UAV energy replenishment system according to claim 6, characterized in that, The component parameters of the transmitter resonant structure and the transmitter auxiliary clamping circuit satisfy the following resonance relationship: Where ω is the operating angular frequency of the system.

8. The UAV energy replenishment system according to claim 1, characterized in that, The receiver resonant structure is a series-compensated topology, including a receiving coil (L... s ) and the second resonant capacitor (C s The receiving coil (L) s ) and the second resonant capacitor (C) s A series connection satisfies the following relationship: Where ω is the operating angular frequency of the system.

9. The UAV energy replenishment system according to claim 8, characterized in that, The passive rectification structure is a full-bridge passive rectifier, consisting of a first rectifier diode (D3), a second rectifier diode (D4), a third rectifier diode (D5), and a fourth rectifier diode (D6), and is connected to an output filter capacitor (C). b ); Wherein, the receiving coil (L) s One end and the second resonant capacitor (C) s One end is connected to the anode of the first rectifier diode (D3), and the other end is connected to the cathode of the second rectifier diode (D4). The second resonant capacitor (C) s One end and the receiving coil (L) s The anode of the third rectifier diode (D5) and the cathode of the fourth rectifier diode (D6) are connected. The output filter capacitor (C) b The diodes are connected in parallel at both ends of the passive rectifier structure. One end is connected to the cathode of the first rectifier diode (D3) and the third rectifier diode (D5), and the other end is connected to the cathode of the second rectifier diode (D4) and the fourth rectifier diode (D6).

10. The method according to claim 1, characterized in that, The relationship satisfied by the DC-AC inverter structure is:

11. The UAV energy replenishment system according to any one of claims 1 to 10, characterized in that, During the constant current output phase of the UAV energy replenishment system, the system's output current I b The expression is: Where ω is the system's operating angular frequency, M ps This represents the mutual inductance between the transmitting and receiving coils.

12. The UAV energy replenishment system according to claim 11, characterized in that, The termination resistor R during the charging transition phase of the UAV energy replenishment system L2 The expression is:

13. The UAV energy replenishment system according to claim 12, characterized in that, During the constant voltage output phase, the system's output voltage (V) b It is determined by the following formula: Among them, L r The clamping inductor is used to assist in the clamping circuit.

14. An unmanned aerial vehicle (UAV), characterized in that, The system includes any one of claims 1 to 13 for charging its onboard lithium-ion battery.

Images