A fully active controlled hydrogen-electric composite power supply system and control method for unmanned aerial vehicles

Abstract

A fully actively controlled hydrogen-electric composite power supply system for an unmanned aerial vehicle (UAV) and a control method thereof include a fuel cell and a lithium battery. The fuel cell positive electrode is connected to the drain electrodes of NMOS switching tubes N1 and NMOS switching tubes N2. The source electrode of NMOS switching tube N1 is connected to the positive electrode of diode D2. The negative electrode of diode D2 is connected to the positive electrode of a load output terminal. The source electrode of NMOS switching tube N2 is connected to the negative electrode of diode D1 and the input terminal of inductor L. The output terminal of inductor L is connected to the drain electrode of NMOS switching tube N3 and the positive electrode of diode D3. The negative electrode of diode D3 is connected to the drain electrode of PMOS switching tube P1 and the positive electrode of the load output terminal. The source electrode of PMOS switching tube P1 is connected to the positive electrode of the lithium battery. The negative electrode of the fuel cell is connected to the positive electrode of diode D1, the source electrode of NMOS switching tube N3, the negative electrode of the lithium battery, and the negative electrode of the load output terminal. By controlling the on / off of NMOS switching tubes N1, N2, and N3 and PMOS switching tube P1, direct output of the fuel cell, direct output of the lithium battery, and coordinated buck-boost output are achieved, thereby enabling the UAV to operate in an optimal state and extending the battery life.

Description

Technical Field

[0001] The present invention belongs to the technical field of power supplies, and in particular relates to a fully actively controlled hydrogen-electric composite power supply system for unmanned aerial vehicles and a control method thereof. Background Art

[0002] In recent years, the ultra-high-bandwidth data transmission of 5G networks has greatly enhanced the remote control capabilities of drones, expanding their application areas to include power inspection, high-rise firefighting, remote sensing mapping, medical rescue, and other scenarios, generating significant economic and social benefits. However, traditional drones, powered solely by lithium batteries, suffer from unsatisfactory flight time and payload capacity. To address these challenges, new energy sources are being considered to replace traditional lithium-ion battery-powered drones. Fuel cells, due to their unique advantages, have become an effective solution for powering mobile devices. However, fuel cells have relatively weak power output characteristics, and single-fuel cell power supply suffers from drawbacks such as insufficient power and slow response. To improve the power output and response speed of fuel cell power sources, fuel cells and lithium batteries can be combined into a hydrogen-electric hybrid power source to meet the diverse flight requirements of drones, including takeoff, acceleration, and cruising.

[0003] A commonly used hydrogen-electric hybrid power topology (published in Applied Energy, "Real-time energy management for fuel cell electric vehicle using speed prediction-based model predictive control considering performance degradation") adds a DC / DC boost converter to the fuel cell output, connected in parallel with a lithium-ion battery to power the load. However, when the load power demand is low, the fuel cell output voltage is high, and a single DC / DC boost converter cannot match the bus voltage. Furthermore, the lithium-ion battery is completely passively controlled, unable to flexibly switch output modes based on demand. This reduces overall system efficiency and shortens the service life of the fuel cell and lithium-ion battery. Summary of the Invention

[0004] To overcome the shortcomings of the above-mentioned prior art, the present invention aims to provide a fully actively controlled hydrogen-electric hybrid power supply system and control method for unmanned aerial vehicles. By controlling the on and off of NMOS switch tubes (N1, N2 and N3) and the PMOS switch tube P1 that is mutually exclusive with the NMOS switch tube N1, three modes of direct output from the fuel cell, direct output from the lithium battery, and coordinated buck-boost output are achieved. This enables the unmanned aerial vehicle to operate in the optimal state, extends the service life of the fuel cell and lithium battery, and improves the working efficiency of the entire system.

[0005] To achieve the above object, the technical solution provided by the present invention is:

[0006] A fully actively controlled hydrogen-electric composite power supply system for an unmanned aerial vehicle (UAV) includes a fuel cell and a lithium battery. The positive electrode of the fuel cell is connected to the drain electrodes of an NMOS switching tube N1 and an NMOS switching tube N2, the source electrode of the NMOS switching tube N1 is connected to the positive electrode of a diode D2, and the negative electrode of the diode D2 is connected to the positive electrode of a load output terminal. The source electrode of the NMOS switching tube N2 is connected to the negative electrode of the diode D1 and the input terminal of an inductor L. The output terminal of the inductor L is connected to the drain electrode of the NMOS switching tube N3 and the positive electrode of the diode D3. The negative electrode of the diode D3 is connected to the drain electrode of a PMOS switching tube P1 and the positive electrode of the load output terminal. The source electrode of the PMOS switching tube P1 is connected to the positive electrode of the lithium battery. The negative electrode of the fuel cell is connected to the positive electrode of the diode D1, the source electrode of the NMOS switching tube N3, the negative electrode of the lithium battery, and the negative electrode of the load output terminal.

[0007] The direct output control circuit of the fuel cell is formed by the NMOS switch tube N1 and the diode D2; the NMOS switch tube N2, the diode D1, the inductor L, the NMOS switch tube N3, and the diode D3 constitute the boost-buck output control circuit of the fuel cell. The NMOS switch tube N2 is not only the overall on / off control switch of the boost-buck output control circuit, but also the PWM signal control switch of the fuel cell's buck output. The NMOS switch tube N2 realizes active control of the boost-buck output; the NMOS switch tube N1 and the PMOS switch tube P1 realize active control of the direct output of the fuel cell and the lithium battery. The NMOS switch tube N3 is the switch controlled by the PWM signal of the fuel cell's boost output.

[0008] The bases (signal control terminals) of the NMOS switch tubes N1, NMOS switch tubes N2, NMOS switch tubes N3 and PMOS switch tubes P1 are all connected to the optocoupler isolation module OC, that is, their high and low level signals and PWM signals all need to be output through the optocoupler isolation module OC.

[0009] A control method for a fully active hydrogen-electric hybrid power system for UAVs is used. By controlling the mutually exclusive on / off switching of NMOS switch N1 and PMOS switch P1, and the on / off switching or PWM control of NMOS switch N2 and NMOS switch N3, three types of fully active control are achieved, including direct output control of the fuel cell, direct output control of the lithium battery, and buck-boost coordinated output control.

[0010] 1) Fuel cell direct output: A high-level signal is used to turn on the NMOS switch N1, while a high-level signal simultaneously turns off the PMOS switch P1, achieving mutually exclusive on-off control of the NMOS switch N1 and the PMOS switch P1. Simultaneously, a low-level signal is used to turn off the NMOS switch N2, cutting off the buck-boost circuit and achieving direct fuel cell output.

[0011] 2) Direct output from lithium batteries: A low-level signal is used to turn on the PMOS switch P1, and a low-level signal is used to turn off the NMOS switch N1, thereby achieving mutually exclusive on-off control of the PMOS switch P1 and the NMOS switch N1. At the same time, a low-level signal is used to turn off the NMOS switch N2, cutting off the buck-boost circuit and achieving direct output from lithium batteries.

[0012] 3) Buck-boost coordinated output: A low-level signal is used to control the PMOS switch tube P1 to be turned on, and a low-level signal is used to control the NMOS switch tube N1 to be turned off at the same time, thereby realizing mutually exclusive on-off control of the PMOS switch tube P1 and the NMOS switch tube N1. While ensuring that the direct output circuit of the lithium battery is turned on, the direct output circuit of the fuel cell is cut off. At this time, the NMOS switch tube N2 and the NMOS switch tube N3 are controlled according to the buck-boost requirements of the fuel cell: when the fuel cell needs to work at a boost voltage, a high-level signal is used to control the NMOS switch tube N2 to be turned on, and a PWM signal is used to control the high-frequency on-off of the NMOS switch tube N3, thereby realizing the boost coordinated output of the hydrogen-electric hybrid power supply system. When the fuel cell needs to work at a buck voltage, a low-level signal is used to control the NMOS switch tube N3 to be turned off, and a PWM signal is used to control the high-frequency on-off of the NMOS switch tube N2, thereby realizing the buck coordinated output of the hydrogen-electric hybrid power supply system.

[0013] Compared with the prior art, the present invention has the following beneficial effects:

[0014] The present invention realizes independent output or coordinated buck-boost output of the fuel cell and lithium battery through mutually exclusive on-off control of the NMOS switch tube N1 and the PMOS switch tube P1, and on-off or PWM control of the NMOS switch tube N2 and the NMOS switch tube N3, and completes direct output control of the fuel cell, direct output control of the lithium battery, and coordinated buck-boost output control, so that the UAV can operate in the optimal state, extend the service life of the fuel cell and lithium battery, and improve the working efficiency of the entire system. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 This is a diagram of the overall structure of the fully active control composite power supply system according to an embodiment of the present invention.

[0016] Figure 2 This is a flow chart of a control method for a fully active control composite power system according to an embodiment of the present invention.

[0017] Figure 3 Schematic diagram of the polarization curve of the fuel cell according to the embodiment of the present invention.

[0018] Figure 4 Schematic diagram of the output voltage of a lithium battery according to an embodiment of the present invention.

[0019] Figure 5 This is a power flow diagram of a fuel cell in single output mode according to an embodiment of the present invention.

[0020] Figure 6 This is a power flow diagram of the lithium battery single output mode in an embodiment of the present invention.

[0021] Figure 7 This is a power flow diagram of the fuel cell boost coordinated lithium battery output mode according to an embodiment of the present invention.

[0022] Figure 8 This is a power flow diagram of a fuel cell boosting and lithium battery charging mode according to an embodiment of the present invention.

[0023] Figure 9 This is a power flow diagram of a fuel cell voltage reduction and lithium battery charging mode according to an embodiment of the present invention. DETAILED DESCRIPTION

[0024] The technical solution of the present invention is further described below with reference to the following embodiments. The embodiments are intended to illustrate the present invention but do not limit the scope of the present invention. The switch tube can be replaced by a switch with the same function, and the capacity of the fuel cell and lithium battery can be selected according to actual conditions.

[0025] It should be noted that the UAV load power and the lithium battery state of charge range are parameters pre-set according to actual needs. For example, in an embodiment of the present invention: the high power load range of the UAV load power can be set to 75% to 95% of the maximum power, the low power range can be set to 5% to 35% of the maximum power, and the medium power range is less than the high power range and greater than the low power range. The lithium battery state of charge (SOC) range limit can be set to 55%. When the lithium battery SOC is greater than 55%, it is considered to be in the high SOC range, and when it is less than 55%, it is considered to be in the low SOC range. Figure 4 shown.

[0026] like Figure 1As shown, a fully actively controlled hydrogen-electric composite power supply system for unmanned aerial vehicles includes a fuel cell and a lithium battery. The positive electrode of the fuel cell is connected to the drain of the NMOS switch tube N1 and the NMOS switch tube N2. The source of the NMOS switch tube N1 is connected to the positive electrode of the diode D2. The negative electrode of the diode D2 is connected to the positive electrode of the load output terminal. The direct output control circuit of the fuel cell is formed by the NMOS switch tube N1 and the diode D2. The source of the NMOS switch tube N2 is connected to the negative electrode of the diode D1 and the input terminal of the inductor L. The output terminal of the inductor L is connected to the drain of the NMOS switch tube N3 and the positive electrode of the diode D3. The negative electrode of the diode D3 is connected to the drain of the PMOS switch tube P1 and the positive electrode of the load output terminal. The source of the PMOS switch tube P1 is connected to the lithium battery. The positive electrode of the fuel cell is connected; the negative electrode of the fuel cell is connected to the positive electrode of the diode D1, the source electrode of the NMOS switch tube N3, the negative electrode of the lithium battery and the negative electrode of the load output terminal are connected; the NMOS switch tube N2, the diode D1, the inductor L, the NMOS switch tube N3, and the diode D3 constitute the boost-buck output control circuit of the fuel cell. The NMOS switch tube N2 is not only the on / off master control switch of the boost-buck output control circuit, but also the PWM signal control switch of the fuel cell buck output. The NMOS switch tube N2 realizes active control of the boost-buck output; the NMOS switch tube N1 and the PMOS switch tube P1 realize active control of the direct output of the fuel cell and the lithium battery. The NMOS switch tube N3 is the switch controlled by the PWM signal of the fuel cell boost output.

[0027] The bases (signal control terminals) of the NMOS switch tubes N1, NMOS switch tubes N2, NMOS switch tubes N3, and PMOS switch tube P1 are all connected to the optocoupler isolation module OC, that is, their high and low level signals and PWM signals all need to be output through the optocoupler isolation module OC to ensure that the drive circuit and the main power circuit are separated.

[0028] A control method for a fully active hydrogen-electric hybrid power system for UAVs is used. By controlling the mutually exclusive on-off control of NMOS switch tube N1 and PMOS switch tube P1, and the on-off or PWM control of NMOS switch tube N2 and NMOS switch tube N3, three types of fully active control are achieved, including direct output control of fuel cells, direct output control of lithium batteries, and step-up and step-down coordinated output control. The power demand of the UAV is divided into three intervals: high, medium, and low. At the same time, the state of charge of the lithium battery (such as Figure 3 As shown), select the appropriate output mode, the specific selection is as follows Figure 2 As shown;

[0029] 1) Fuel cell direct output: When the UAV is in medium power demand and the lithium battery has high SOC, the fuel cell operates in the ohmic loss region and selects the single output mode. At this time, the switch state and power flow are as follows: Figure 5As shown, a high-level signal is used to control the NMOS switch tube N1 to turn on, and the high-level signal simultaneously controls the PMOS switch tube P1 to turn off, thereby realizing mutually exclusive on-off control of the NMOS switch tube N1 and the PMOS switch tube P1; at the same time, a low-level signal is used to control the NMOS switch tube N2 to turn off, cutting off the buck-boost circuit and realizing direct output of the fuel cell;

[0030] 2) Lithium battery direct output: When the UAV is in low power demand and the lithium battery has high SOC, the lithium battery output mode is selected and the fuel cell does not work. At this time, the switch state and power flow are as follows: Figure 6 As shown, a low-level signal is used to control the PMOS switch tube P1 to turn on, and the low-level signal simultaneously controls the NMOS switch tube N1 to turn off, thereby realizing mutually exclusive on-off control of the PMOS switch tube P1 and the NMOS switch tube N1; at the same time, a low-level signal is used to control the NMOS switch tube N2 to turn off, cutting off the buck-boost circuit and realizing direct output of the lithium battery;

[0031] 3) Boost and coordinated output: When the UAV is in high power demand, the fuel cell works in the concentration loss area, and is output in parallel with the lithium battery while boosting. At this time, the switch state and power flow are as follows: Figure 7 As shown, a low-level signal is used to control the PMOS switch tube P1 to be turned on, and the low-level signal simultaneously controls the NMOS switch tube N1 to be turned off, thereby realizing mutually exclusive on-off control of the PMOS switch tube P1 and the NMOS switch tube N1. While ensuring the direct output circuit of the lithium battery is turned on, the direct output circuit of the fuel cell is cut off. At the same time, a high-level signal is used to control the NMOS switch tube N2 to be turned on, and a PWM signal is used to control the high-frequency on-off of the NMOS switch tube N3, thereby realizing the boosted coordinated output of the hydrogen-electric hybrid power system.

[0032] When the UAV is in medium power demand and the lithium battery has low SOC, the fuel cell boost output is used to charge the lithium battery at the same time. Figure 8 As shown, the status of the switch tube is the same as above;

[0033] 4) Buck-coordinated output: When the UAV is in low power demand and the lithium battery is at low SOC, the lithium battery voltage is low, the fuel cell operates in the polarization loss area, and the output voltage is high. It is necessary to buck the output while charging the lithium battery. At this time, the switch state and power flow are as follows: Figure 9 As shown, on the basis of ensuring that the direct output circuit of the lithium battery is turned on and the direct output circuit of the fuel cell is cut off, a low-level signal is used to control the NMOS switch tube N3 to be disconnected, and a PWM signal is used to control the high-frequency switching of the NMOS switch tube N2 to achieve the coordinated output of the fuel cell voltage reduction.

Claims

1. A fully actively controlled hydrogen-electric hybrid power system for unmanned aerial vehicles, comprising a fuel cell and a lithium battery, characterized by: The positive electrode of the fuel cell is connected to the drain electrodes of the NMOS switch tubes N1 and NMOS switch tubes N2, the source electrode of the NMOS switch tube N1 is connected to the positive electrode of the diode D2, and the negative electrode of the diode D2 is connected to the positive electrode of the load output terminal; the source electrode of the NMOS switch tube N2 is connected to the negative electrode of the diode D1 and the input terminal of the inductor L, the output terminal of the inductor L is connected to the drain electrode of the NMOS switch tube N3 and the positive electrode of the diode D3, the negative electrode of the diode D3 is connected to the drain electrode of the PMOS switch tube P1 and the positive electrode of the load output terminal, and the source electrode of the PMOS switch tube P1 is connected to the positive electrode of the lithium battery; the negative electrode of the fuel cell is connected to the positive electrode of the diode D1, the source electrode of the NMOS switch tube N3, the negative electrode of the lithium battery, and the negative electrode of the load output terminal; The direct output control circuit of the fuel cell is formed by the NMOS switch tube N1 and the diode D2. The NMOS switch tube N2, the diode D1, the inductor L, the NMOS switch tube N3, and the diode D3 form the boost / buck output control circuit of the fuel cell. The NMOS switch tube N2 is not only the overall on / off control switch of the boost / buck output control circuit, but also the PWM signal control switch of the fuel cell's buck output. The NMOS switch tube N2 realizes active control of the boost / buck output. The NMOS switch tube N1 and the PMOS switch tube P1 realize active control of the direct output of the fuel cell and the lithium battery. The NMOS switch tube N3 is the PWM signal control switch of the fuel cell's boost output. The bases or signal control terminals of the NMOS switch tubes N1, NMOS switch tubes N2, NMOS switch tubes N3 and PMOS switch tube P1 are all connected to the optocoupler isolation module OC, that is, their high and low level signals and PWM signals all need to be output through the optocoupler isolation module OC.

2. A power supply control method for a fully actively controlled hydrogen-electric hybrid power supply system for a UAV according to claim 1, characterized in that: By controlling the mutually exclusive on / off switching of NMOS switch N1 and PMOS switch P1, and the on / off switching or PWM control of NMOS switch N2 and NMOS switch N3, three types of fully active control are achieved, including direct output control of fuel cells, direct output control of lithium batteries, and buck-boost coordinated output control. 1) Fuel cell direct output: A high-level signal is used to turn on the NMOS switch N1, while a high-level signal simultaneously turns off the PMOS switch P1, achieving mutually exclusive on-off control of the NMOS switch N1 and the PMOS switch P1. At the same time, a low-level signal is used to turn off the NMOS switch N2, cutting off the buck-boost circuit and achieving direct fuel cell output. 2) Direct output from lithium batteries: A low-level signal is used to turn on the PMOS switch P1, and a low-level signal is used to turn off the NMOS switch N1, thereby achieving mutually exclusive on-off control of the PMOS switch P1 and the NMOS switch N1. At the same time, a low-level signal is used to turn off the NMOS switch N2, cutting off the buck-boost circuit and achieving direct output from lithium batteries. 3) Buck-boost coordinated output: A low-level signal is used to control the PMOS switch tube P1 to be turned on, and a low-level signal is used to control the NMOS switch tube N1 to be turned off at the same time, realizing the mutually exclusive on-off control of the PMOS switch tube P1 and the NMOS switch tube N1, while ensuring that the direct output circuit of the lithium battery is turned on, while cutting off the direct output circuit of the fuel cell; at this time, the NMOS switch tube N2 and the NMOS switch tube N3 are controlled according to the buck-boost requirements of the fuel cell: when the fuel cell needs to work at boost, a high-level signal is used to control the NMOS switch tube N2 to be turned on, and a PWM signal is used to control the high-frequency on-off of the NMOS switch tube N3, realizing the boost coordinated output of the hydrogen-electric hybrid power supply system; when the fuel cell needs to work at buck, a low-level signal is used to control the NMOS switch tube N3 to be turned off, and a PWM signal is used to control the high-frequency on-off of the NMOS switch tube N2, realizing the buck coordinated output of the hydrogen-electric hybrid power supply system.

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