Double-loop safe mooring battery and mooring unmanned aerial vehicle

Abstract

The invention relates to the technical field of unmanned aerial vehicle batteries, in particular to a double-loop safety mooring battery which comprises a DC / DC module, a lithium battery and a BMS module, the BMS module is connected with the lithium battery, the BMS module is in communication connection with the DC / DC module, an output branch of the DC / DC module and an input and output branch of the lithium battery are both connected to a contact with a total output line, and the total output line is used for supplying power to an unmanned aerial vehicle; the voltage control loop is used for adjusting the output voltage of the DC / DC module according to the total voltage when the highest single voltage of the lithium battery reaches the full voltage; and the current loop is used for adjusting the output current of the DC / DC module according to the charging current of the lithium battery. The charging current of the lithium battery can be locked in a safe charging current range, and the output voltage can be dynamically tracked according to the unbalance degree of the lithium battery to prevent overcharge; when the temperature of the lithium battery is too high, potential safety hazards can be prevented by limiting the charging current; and the safety of the lithium battery on the unmanned aerial vehicle is ensured from multiple dimensions.

Description

Technical Field

[0001] The present invention relates to the technical field of UAV batteries, and particularly relates to a dual-loop safety tethered battery and a tethered UAV. Background Art

[0002] A tethered UAV, also known as a tethered unmanned aerial vehicle, uses a ground power source transmitted through a tether cable as the power source, replacing traditional lithium batteries. The most important feature is its long-duration hovering ability. During flight, due to reasons such as the breakage or poor contact of the tether cable, the UAV cannot fly normally. Generally, a small-capacity lithium battery is reserved to handle emergencies. However, the lithium battery has limited ability to withstand the charging current, and overcharging the current can lead to a high risk of fire. In the application scenario of tethered UAVs, the output current of the DC / DC module far exceeds the current that the lithium battery itself can withstand, making it very easy to overcharge the current; tethered UAVs work continuously for a long time, and the probability of overheating is very high. Charging the lithium battery with a large current at high temperatures can lead to a high risk of fire. Different degrees of imbalance will occur during the use of lithium batteries. The imbalance will cause overcharging of individual cells under normal total charging voltage, and overcharging of individual cells will directly lead to a risk of fire. In the UAV power supply system, the battery pack cannot initiate a protection action, otherwise it will bring greater disasters. Summary of the Invention

[0003] The purpose of the present invention is to provide a dual-loop safety tethered battery to solve the safety hazard problems existing in the lithium batteries of existing tethered UAVs. Another purpose of the present invention is to provide a tethered UAV equipped with the tethered battery.

[0004] To achieve the above purpose, the present invention adopts the following technical solutions:

[0005] A dual-loop safety tethered battery includes a DC / DC module, a lithium battery, and a BMS module. The BMS module is connected to the lithium battery, and the BMS module is communicatively connected to the DC / DC module. The output branch of the DC / DC module and the input / output branch of the lithium battery are both connected to the total output line at a connection point, and the total output line is used to supply power to the UAV;

[0006] It further includes a voltage control loop that adjusts the output voltage of the DC / DC module according to the total voltage when the highest single-cell voltage of the lithium battery reaches the full charge voltage;

[0007] A current loop that adjusts the output current of the DC / DC module according to the charging current of the lithium battery and limits the maximum current to prevent overcharging of the lithium battery.

[0008] Furthermore, the BMS module feeds back the data of the charging current and the voltage of each single cell of the lithium battery to the DC / DC module to limit the maximum charging current of the lithium battery.

[0009] Further, the BMS module also feeds back the temperature data of the lithium battery to the DC / DC module, and limits the maximum charging current when the temperature is too high.

[0010] Further, the voltage control loop prevents any battery cell in the lithium battery from being overcharged by controlling the output voltage of the DC / DC module.

[0011] Further, the current in the input and output branches of the lithium battery can flow into the lithium battery for charging, or can flow out of the lithium battery to supply power to the drone.

[0012] Further, the current loop includes the following control modes: (1) Normal state: The lithium battery is fully charged, and the DC / DC module supplies power to the drone.

[0013] (2) High load state: The DC / DC module outputs the maximum current to supply power to the drone, and the lithium battery is in a discharging state to supply power to the drone.

[0014] (3) Recovery load state and light load charging state: The charging current of the lithium battery does not exceed the set maximum charging current.

[0015] Further, the tethered battery is a modular structure and can be used to be installed on the drone.

[0016] A tethered drone, comprising a fuselage, a battery compartment is provided on the fuselage, and the double-loop safety tethered battery according to any one of claims 1 to 6 is installed in the battery compartment.

[0017] Advantages of the present invention:

[0018] The tethered battery of the present invention is composed of a lithium battery, a DC / DC module, and a BMS module. The BMS module outputs the current, temperature, and single-cell voltage data of the lithium battery through the CAN bus, and inputs them to the DC / DC module for closed-loop control and protection. The charging current of the lithium battery is locked within the safe charging current range. When the temperature of the lithium battery is too high, the charging current is also limited to prevent potential safety hazards, and the output voltage is dynamically tracked according to the imbalance degree of the lithium battery to ensure safety. From multiple dimensions such as voltage, current, and temperature, the safety of the lithium battery is ensured. Description of the Drawings

[0019] Figure 1 is the schematic diagram of the double-loop safety tethered battery of the present invention;

[0020] Figure 2 is the schematic diagram of the connection between the double-loop safety tethered battery of the present invention and the ground station and the drone load;

[0021] Figure 3 is the control schematic diagram of the double-loop safety tethered battery of the present invention. Detailed Embodiments

[0022] The following will clearly and completely describe the technical solutions in the embodiments of the present invention with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art shall fall within the protection scope of the present invention.

[0023] Embodiments of the present invention:

[0024] As Figure 1 and 2 shown, a dual-loop safety tethered battery includes a DC / DC module, a lithium battery, and a BMS module. The BMS module is connected to the lithium battery, and the BMS module is communicatively connected to the DC / DC module. The output branch of the DC / DC module and the input / output branch of the lithium battery are both connected to the total output line at a contact point. The total output line is used to supply power to the unmanned aerial vehicle (UAV), and there are no other isolation devices, so the efficiency is high.

[0025] The BMS module, which can also be called the BMS management system, outputs the current, temperature, and single-cell voltage data of the lithium battery through the CAN bus. These data are input to the DC / DC module for closed-loop control and protection.

[0026] The tethered battery in this embodiment is a modular structure, which can be used to be installed on a tethered UAV, and the tethered battery can be removed. If the tethered battery is made to have the same shape and power-on interface as the battery of a conventional UAV (non-tethered), switching can also be achieved, that is, the tethered battery of the tethered UAV is removed and replaced with a conventional battery, then it can be used as a conventional UAV, improving the utilization rate of the UAV.

[0027] The tethered UAV transmits high-voltage direct current to the UAV through a tethered cable connected to the ground station at one end, and then steps down the voltage through the DC / DC module to supply power to the UAV. Using high-voltage direct current transmission makes the current smaller for the same power, achieving the purpose of reducing the core wire diameter of the tethered cable.

[0028] As Figure 1 shown in the schematic diagram, where the current I1 can flow into the node to supply power to the UAV and can also flow out of the node to charge the lithium battery; the current I2 is output by the DC / DC module and can only flow into the node unidirectionally; the current I3 is output to the UAV load and can only flow out of the node unidirectionally. At any moment, the sum of the currents flowing into the node is equal to the sum of the currents flowing out of the node, and I3 = I1 + I2.

[0029] To improve the safety of the battery, the present invention designs a current loop and a voltage loop. The current loop dynamically adjusts the output current of the DC / DC module according to the charging current of the lithium battery.

[0030] The BMS module feeds back the data of the charging current and the voltage of each single cell of the lithium battery to the DC / DC module, limits the maximum charging current of the lithium battery, and achieves the purpose of preventing overcharging. The BMS module also feeds back the temperature data of the lithium battery to the DC / DC module, and limits the maximum charging current when the temperature is too high to slow down the temperature rise of the lithium battery.

[0031] Regarding the principle of the current loop, an example is given as follows:

[0032] Suppose the lithium battery is a ternary 14S20AH with a maximum charging power of 3KW; the DC / DC module is 12KW, 60.9V 197A.

[0033] There are the following several control modes: (1) Normal state: The power of the drone is 8KW, and the lithium battery is fully charged. The DC / DC module supplies power to the drone.

[0034] (2) High-load state: The power of the drone is 15KW, and the DC / DC module outputs the maximum power of 12KW, that is, the maximum current to supply power to the drone. The lithium battery is in a discharging state to supply power to the drone. The output power of the lithium battery is 3KW. The DC / DC module and the lithium battery jointly meet the high-power requirements of the drone.

[0035] (3) Recovery load state: The power of the drone is 8KW. The DC / DC module supplies power to the drone and charges the lithium battery at the same time. The charging current does not exceed the set maximum charging current. That is, the maximum charging power provided by the DC / DC module to the lithium battery is 3KW, not exceeding 3KW. Therefore, the charging current will not overcharge. The maximum charging current theoretically does not exceed Imax = 3kW / 60.9V = 49.3A.

[0036] (4) Light-load charging state: The power of the drone is 6KW. The power supply of the drone is provided by the DC / DC module. The charging power of the lithium battery is locked at 3KW, and the total output power of the DC / DC module is 9KW.

[0037] The voltage control loop adjusts the output voltage of the DC / DC module according to the total voltage when the highest single-cell voltage of the lithium battery reaches the full charge voltage. The lithium battery includes several battery cells. The voltage control loop prevents any battery cell in the lithium battery from overcharging by controlling the output voltage of the DC / DC module.

[0038] When the lithium battery is in the balanced state: the voltage of each single cell of the lithium battery is 4.35V, and the output voltage of the DC / DC module is 60.9V;

[0039] When the battery pack is in an unbalanced state: if a single lithium battery cell has a voltage of 4.35V and the rest are all 4.20V, the output voltage of the DC / DC module is 58.95V. The single cell with a smaller capacity will reach the charging upper limit voltage faster, triggering the protection mechanism and forcing the charging to terminate. At this time, the other single cells may not be fully charged, but it does not affect the normal use of the lithium battery, and the safety is guaranteed.

[0040] The method adopted by the present invention is current-mode control, which has a fast response speed and can quickly respond to the transient change of the input voltage. It includes the above-mentioned current loop and voltage loop, belonging to double-loop control. For the specific current-mode control principle, reference can be made to Figure 3 .

[0041] As Figure 3 shown, it is the control principle diagram of the double-loop safety tethered battery of the present invention. U o represents the voltage of the lithium battery detected by the BMS module, and U n is the set reference voltage. The deviation signal between the detected voltage U o and the reference voltage U n is obtained as a voltage signal through an error amplifier, and then compared with the feedback current signal. The output signal after comparison is processed and then transmitted to the DC / DC module through the CAN bus, and the DC / DC module adjusts the output.

[0042] Embodiment of the tethered drone:

[0043] The tethered drone includes a fuselage, and a battery compartment is provided on the fuselage. These are prior arts and will not be elaborated here. The double-loop safety tethered battery described above is installed in the battery compartment.

Claims

1. A double-loop safety tethered battery, characterized in that: It includes a DC / DC module, a lithium battery and a BMS module. The BMS module is connected to the lithium battery, and the BMS module is communicatively connected to the DC / DC module. The output branch of the DC / DC module and the input / output branch of the lithium battery are both connected to the total output line at a contact point, and the total output line is used to supply power to the drone. It further includes a voltage loop that adjusts the output voltage of the DC / DC according to the total voltage when the highest single-cell voltage of the lithium battery reaches the full charge voltage. A current loop that adjusts the output current of the DC / DC according to the charging current of the lithium battery and limits the maximum charging current to prevent overcharging of the lithium battery.

2. The dual-loop safety tethered battery according to claim 1, wherein: The BMS module feeds back the data of the charging current and the voltage of each single cell of the lithium battery to the DC / DC module to limit the maximum charging current of the lithium battery.

3. The double-loop safety tethered battery according to claim 2, wherein: The BMS module also feeds back the temperature data of the lithium battery to the DC / DC module to limit the maximum charging current when the temperature is too high.

4. The double-loop safety tethered battery according to claim 1, wherein: The voltage control loop prevents any single cell in the lithium battery from being overcharged by controlling the output voltage of the DC / DC module.

5. The double-loop safety tethered battery according to claim 1, wherein: The current in the input / output branch of the lithium battery can flow into the lithium battery for charging or flow out of the lithium battery to supply power to the drone.

6. The double-loop safety tethered battery according to claim 5, wherein: The current loop includes the following control modes: (1) Normal state: The lithium battery is fully charged, and the DC / DC module supplies power to the drone. (2) High-load state: The DC / DC module outputs the maximum current to supply power to the drone, and the lithium battery is in a discharging state to supply power to the drone. (3) Recovery load state and light-load charging state: The charging current of the lithium battery does not exceed the set maximum charging current.

7. The dual-loop safety tethered battery according to claim 1, characterized in that: The tethered battery is a modular structure and can be used to be installed on the drone.

8. Tethered drone, including a fuselage, with a battery compartment provided on the fuselage, characterized in that: The battery compartment is equipped with the dual-loop safety tethered battery according to any one of claims 1 to 6.

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