Hydrogen fuel cell and lithium battery hybrid power supply system for unmanned aerial vehicle and control method

Abstract

The invention relates to a hydrogen fuel cell and lithium battery hybrid power supply system and a control method, the hydrogen fuel cell and lithium battery hybrid power supply system comprises a group of hydrogen fuel cells, a group of lithium batteries BT1 and a circuit composed of different MOS transistors, and the circuit comprises a hydrogen fuel cell and lithium battery matching output circuit, a hydrogen fuel cell direct output circuit, a lithium battery buck-boost output circuit and an energy recovery circuit; switching among different circuits can be realized by controlling switches of different MOS tubes, the voltage of a hydrogen fuel cell and the voltage of a lithium battery can be matched, the voltage requirement of a motor driver of the unmanned aerial vehicle is met, and efficient recycling of energy is realized.

Description

Technical Field

[0001] The present invention belongs to the technical field of hydrogen fuel cell unmanned aerial vehicles, and particularly relates to a hybrid power system and control method of a hydrogen fuel cell and a lithium battery for an unmanned aerial vehicle. Background Art

[0002] Currently, the power systems of unmanned aerial vehicles generally rely on lithium batteries for power supply. The limitation of their energy density results in the flight time being difficult to exceed 2 hours. Although hydrogen fuel cells can provide a higher energy density, their output voltage has significant load sensitivity. Taking a 1 kW fuel cell stack as an example, when the load current suddenly increases by 50%, the voltage drop amplitude can reach 30 - 40%, and the power density is relatively low, making it difficult to meet the instantaneous high-power demand during the takeoff stage of unmanned aerial vehicles.

[0003] A single energy system cannot balance high energy density, high power density, and dynamic working condition adaptability, severely restricting the long-endurance and high-maneuverability capabilities of industrial-grade unmanned aerial vehicles. On the other hand, the fluctuating electric energy generated by rotor power generation during the descent stage of unmanned aerial vehicles, due to the lack of efficient management, will directly charge the lithium battery pack and reduce its lifespan. With the development of unmanned aerial vehicles towards heavy-duty and long-endurance applications in fields such as logistics, inspection, and meteorological monitoring, there is an urgent need for a power system that can achieve efficient hydrogen-electric collaboration, dynamic voltage regulation, and intelligent energy recovery, while ensuring high-power output, extending the flight time, and meeting the reliability requirements under complex working conditions. Summary of the Invention

[0004] In order to overcome the above-mentioned disadvantages of the prior art, the purpose of the present invention is to provide a hybrid power system and control method of a hydrogen fuel cell and a lithium battery for an unmanned aerial vehicle, which can match the voltages of the hydrogen fuel cell and the lithium battery, meet the voltage requirements of the unmanned aerial vehicle motor driver, and achieve efficient recovery and utilization of energy.

[0005] In order to achieve the above purpose, the technical solution adopted by the present invention is as follows:

[0006] A hybrid power supply system for an unmanned aerial vehicle using a hydrogen fuel cell and a lithium battery, comprising a set of hydrogen fuel cells and a set of lithium batteries BT1. The positive electrode of the hydrogen fuel cell is connected to the drain of the NMOS transistor Q1, the negative electrode of the hydrogen fuel cell is connected to the negative electrode of the diode D1, and the positive electrode of the diode D1 is connected to the positive electrode of the diode D2, the source of the NMOS transistor Q3, the negative electrode of the lithium battery BT1, the positive electrode of the diode D7, and the source of the NMOS transistor Q6; the source of the NMOS transistor Q1 is connected to the drain of the NMOS transistor Q2, the negative electrode of the diode D3, the negative electrode of the diode D5, the drain of the NMOS transistor Q4, the drain of the NMOS transistor Q8, and the drain of the NMOS transistor Q10; the negative electrode of the diode D2 is connected to the source of the NMOS transistor Q2 and one end of the inductor L1; the drain of the NMOS transistor Q3 is connected to the positive electrode of the diode D3 and the other end of the inductor L1; the positive electrode of the lithium battery BT1 is connected to the negative electrode of the diode D4 and the drain of the NMOS transistor Q5; the capacitor C1 is connected in parallel with the lithium battery BT1; the negative electrode of the diode D7 is connected to the drain of the NMOS transistor Q6, the drain of the NMOS transistor Q7, the negative electrode of the diode D9, and the source of the NMOS transistor Q11; the source of the NMOS transistor Q5 is connected to the source of the NMOS transistor Q4, the positive electrode of the diode D4, the negative electrode of the diode D6, and the positive electrode of the diode D5; the positive electrode of the diode D6 is connected to one end of the inductor L2, and the other end of the inductor L2 is connected to the source of the NMOS transistor Q7; the positive electrode of the motor is connected to the drain of the NMOS transistor Q9 and the negative electrode of the diode D8; the negative electrode of the motor is connected to the source of the NMOS transistor Q10 and the drain of the NMOS transistor Q11; the capacitor C2 is connected in parallel with the motor; the positive electrode of the diode D8 is connected to the source of the NMOS transistor Q8; the positive electrode of the diode D9 is connected to the source of the NMOS transistor Q9.

[0007] The hydrogen fuel cell, NMOS transistor Q1, NMOS transistor Q2, inductor L1, NMOS transistor Q3, diode D1, diode D2, diode D3, NMOS transistor Q8, diode D8, capacitor C2, motor, NMOS transistor Q11, NMOS transistor Q6, lithium battery BT1, capacitor C1, NMOS transistor Q5, and diode D5 form a matching output circuit for the hydrogen fuel cell and the lithium battery; the hydrogen fuel cell, NMOS transistor Q1, NMOS transistor Q8, diode D8, capacitor C2, motor, NMOS transistor Q11, NMOS transistor Q6, diode D1, NMOS transistor Q4, diode D4, lithium battery BT1, and capacitor C1 form a direct output circuit for the hydrogen fuel cell; the lithium battery BT1, capacitor C1, NMOS transistor Q5, diode D5, NMOS transistor Q2, inductor L1, NMOS transistor Q3, NMOS transistor Q8, diode D8, capacitor C2, motor, NMOS transistor Q11, and NMOS transistor Q6 form a buck-boost output circuit for the lithium battery; the motor, capacitor C2, NMOS transistor Q9, diode D9, NMOS transistor Q7, inductor L2, diode D6, diode D5, NMOS transistor Q10, lithium battery BT1, capacitor C1, diode D7, and diode D4 form an energy recovery circuit.

[0008] Control method for a hybrid power system of a hydrogen fuel cell and a lithium battery for an unmanned aerial vehicle:

[0009] When the unmanned aerial vehicle needs to output high power, start the matching output circuit of the hydrogen fuel cell and the lithium battery; NMOS transistor Q1, NMOS transistor Q5, and NMOS transistor Q11 are turned on, NMOS transistor Q8 remains off, and NMOS transistors Q2 and Q3 are turned on and off synchronously at high frequency and are mutually exclusive with NMOS transistor Q6 for conduction and shutdown; when NMOS transistors Q2 and Q3 are turned on and NMOS transistor Q6 is turned off, the current starts from the positive electrode of the hydrogen fuel cell and sequentially passes through NMOS transistor Q1, NMOS transistor Q2, inductor L1, NMOS transistor Q3, diode D1 and finally returns to the negative electrode of the hydrogen fuel cell; when NMOS transistors Q2 and Q3 are turned off and NMOS transistor Q6 is turned on, the current in inductor L1 starts from inductor L1 and sequentially passes through diode D3, NMOS transistor Q8, diode D8, capacitor C2 and the motor, NMOS transistor Q11, NMOS transistor Q6, and diode D2 and returns to inductor L1, and the current in lithium battery BT1 passes through from the positive electrode of lithium battery BT1 and sequentially passes through NMOS transistor Q5, diode D5, NMOS transistor Q8, diode D8, capacitor C2 and the motor, NMOS transistor Q11, NMOS transistor Q6 and finally flows into the negative electrode of lithium battery BT1; when the duty cycle D of the conduction of NMOS transistors Q2 and Q3 is greater than 0.5, the hydrogen fuel cell is boosted and connected in parallel with lithium battery BT1 to supply power to the motor; when the duty cycle D of the conduction of NMOS transistors Q2 and Q3 is less than 0.5, the hydrogen fuel cell is bucked and connected in parallel with lithium battery BT1 to supply power to the motor.

[0010] When the power required by the unmanned aerial vehicle is low, start the direct output circuit of the hydrogen fuel cell; NMOS transistor Q1, NMOS transistor Q8, NMOS transistor Q11, and NMOS transistor Q6 are turned on; the current starts from the positive electrode of the hydrogen fuel cell and sequentially passes through NMOS transistor Q1, NMOS transistor Q8, diode D8, capacitor C2 and the motor, NMOS transistor Q11, NMOS transistor Q6, and diode D1 and finally returns to the negative electrode of the hydrogen fuel cell; when the SOC of lithium battery BT1 is lower than a certain value at this time, NMOS transistor Q4 is turned on and the hydrogen fuel cell charges lithium battery BT1 while supplying power to the motor, and a part of the current flows through NMOS transistor Q1 and then sequentially passes through NMOS transistor Q4, diode D4, capacitor C1 and lithium battery BT1 and then flows to diode D1.

[0011] When the SOC value of the hydrogen fuel cell is lower than a certain value and the SOC value of the lithium battery BT1 is higher than a certain value, the lithium battery BT1 supplies power to the motor, the lithium battery buck-boost power supply circuit is turned on, and the NMOS transistors Q5, Q11, and Q6 are turned on; the NMOS transistors Q2, Q3, and Q8 are turned on and off in a high-frequency mutually exclusive manner; when the NMOS transistors Q2 and Q3 are turned on and the NMOS transistor Q8 is turned off, the current starts from the positive electrode of the lithium battery BT1 and flows through the NMOS transistor Q5, the diode D5, the NMOS transistor Q2, the inductor L1, and the NMOS transistor Q3 in sequence and then returns to the negative electrode of the lithium battery BT1; when the NMOS transistors Q2 and Q3 are turned off and the NMOS transistor Q8 is turned on, the current starts from the inductor L1 and flows through the diode D3, the NMOS transistor Q8, the diode D8, the capacitor C2 and the motor, the NMOS transistors Q11 and Q6, and the diode D2 in sequence and then returns to the inductor L1; when the duty cycle D of the NMOS transistors Q2 and Q3 being turned on is greater than 0.5, the lithium battery boosts the output; when the duty cycle D of the NMOS transistors Q2 and Q3 being turned on is less than 0.5, the lithium battery steps down the output.

[0012] When the energy recovery circuit is turned on, the NMOS transistors Q7 and Q9 are turned on, and the NMOS transistor Q10 is turned on and off at a high frequency; when the NMOS transistor Q10 is turned on, the current generated in the motor starts from the motor and flows through the NMOS transistor Q9, the diode D9, the NMOS transistor Q7, the inductor L2, the diode D6, the diode D5, and the NMOS transistor Q10 in sequence and then returns to the motor; when the NMOS transistor Q10 is turned off, the current starts from the inductor L2 and flows through the diode D6, the diode D4, the lithium battery BT1 and the capacitor C2, the diode D7, and the NMOS transistor Q7 in sequence and then returns to the inductor L2; when the duty cycle D of the NMOS transistor Q10 being turned on is greater than 0.5, the electricity generated by the motor is boosted and then used to charge the lithium battery BT1, and when the duty cycle D of the NMOS transistor Q10 being turned on is less than 0.5, the electricity generated by the motor is stepped down and then used to charge the lithium battery BT1.

[0013] Compared with the prior art, the present invention has the following advantages: the present invention can achieve the matching output of the hydrogen fuel cell and the lithium battery, the direct output of the hydrogen fuel cell, and the buck-boost power supply of the lithium battery; the Buck-Boost DC converter of the present invention includes a bridge circuit composed of two NMOS transistors and two diodes, and the bridge circuit can change the direction of the output voltage to ensure that the load voltage and the hydrogen fuel cell voltage have the same direction, which is convenient for the parallel output voltage with the lithium battery; the present invention also has an efficient energy recovery circuit, which can recover energy during the landing process of the unmanned aerial vehicle or in a strong wind environment, improving the endurance of the unmanned aerial vehicle. Description of the Drawings

[0014] Figure 1It is a schematic structural diagram of a hybrid power system of a hydrogen fuel cell and a lithium battery for an unmanned aerial vehicle according to an embodiment of the present invention.

[0015] Figure 2(a) is a matching output circuit I of a hydrogen fuel cell and a lithium battery for an unmanned aerial vehicle according to an embodiment of the present invention; Figure 2(b) is a matching output circuit II of a hydrogen fuel cell and a lithium battery.

[0016] Figure 3(a) is a direct output circuit I of a hydrogen fuel cell according to an embodiment of the present invention; Figure 3(b) is a direct output circuit II of a hydrogen fuel cell according to an embodiment of the present invention.

[0017] Figure 4(a) is a buck-boost output circuit I of a lithium battery according to an embodiment of the present invention; Figure 4(b) is a buck-boost output circuit II of a lithium battery according to an embodiment of the present invention.

[0018] Figure 5(a) is an energy recovery circuit I according to an embodiment of the present invention; Figure 5(b) is an energy recovery circuit II according to an embodiment of the present invention. Detailed implementation manners

[0019] The present invention will be further explained below in conjunction with the accompanying drawings and embodiments. It should be noted that the models, specifications and specific parameters of the electrical components in this embodiment can be selected according to actual needs. The NMOS transistor in this embodiment is the MOSFET switch tube, and the "switch tube" means that it is used as a switch. Those skilled in the art can understand that MOSFET includes two types: NMOS and PMOS. For the NMOS type, the MOSFET is turned on when the control signal applied to the gate is at a high level, and the MOSFET is turned off when the control signal applied to the gate is at a low level; while the PMOS type is just the opposite of the NMOS type. Of course, the switch tube in this embodiment can also use the PMOS analogy. When selecting the capacitor C1, it is required that the voltage across the capacitor C1 is greater than the highest voltage across the lithium battery BT1 connected in parallel with the capacitor C1 when it reaches the maximum value; when selecting the capacitor C2, the voltage across the capacitor C2 is greater than the rated voltage of the motor connected in parallel with the capacitor when it reaches the maximum value. The duty cycle is a physical quantity that describes the proportion of the high-level time in a periodic signal. In this embodiment, D is used to represent the duty cycle, V out is the output voltage of the buck-boost circuit, V in is the input voltage of the buck-boost circuit. From the formula V out = V in ·D / (1 - D), it can be seen that the output voltage can be adjusted by adjusting the duty cycle.

[0020] Such as Figure 1As shown in the figure, a hybrid power system of a hydrogen fuel cell and a lithium battery for a drone includes a group of hydrogen fuel cells, a group of lithium batteries BT1, a motor, NMOS transistors Q1 to Q11, diodes D1 to D9, inductors L1, L2, capacitors C1, C2; the positive electrode of the hydrogen fuel cell is connected to the drain of NMOS transistor Q1, the negative electrode of the hydrogen fuel cell is connected to the negative electrode of diode D1, and the positive electrode of diode D1 is connected to the positive electrode of diode D2, the source of NMOS transistor Q3, the negative electrode of lithium battery BT1, the positive electrode of diode D7, and the source of NMOS transistor Q6; the source of NMOS transistor Q1 is connected to the drain of NMOS transistor Q2, the negative electrode of diode D3, the negative electrode of diode D5, the drain of NMOS transistor Q4, the drain of NMOS transistor Q8, and the drain of NMOS transistor Q10; the negative electrode of diode D2 is connected to the source of NMOS transistor Q2 and one end of inductor L1; the drain of NMOS transistor Q3 is connected to the positive electrode of diode D3 and the other end of inductor L1; the positive electrode of lithium battery BT1 is connected to the negative electrode of diode D4 and the drain of NMOS transistor Q5; capacitor C1 is connected in parallel with battery BT1; the negative electrode of diode D7 is connected to the drain of NMOS transistor Q6, the drain of NMOS transistor Q7, the negative electrode of diode D9, and the source of NMOS transistor Q11; the source of NMOS transistor Q5 is connected to the source of NMOS transistor Q4, the positive electrode of diode D4, the negative electrode of diode D6, and the positive electrode of diode D5; the positive electrode of diode D6 is connected to one end of inductor L2; the other end of inductor L2 is connected to the source of NMOS transistor Q7; the positive electrode of the motor is connected to the drain of NMOS transistor Q9 and the negative electrode of diode D8; the negative electrode of the motor is connected to the source of NMOS transistor Q10 and the drain of NMOS transistor Q11; capacitor C2 is connected in parallel with the motor; the positive electrode of diode D8 is connected to the source of NMOS transistor Q8; the positive electrode of diode D9 is connected to the source of NMOS transistor Q9.

[0021] The hydrogen fuel cell, NMOS transistor Q1, NMOS transistor Q2, inductor L1, NMOS transistor Q3, diode D1, diode D2, diode D3, NMOS transistor Q8, diode D8, capacitor C2, motor, NMOS transistor Q11, NMOS transistor Q6, lithium battery BT1, capacitor C1, NMOS transistor Q5, and diode D5 form a matching output circuit for the hydrogen fuel cell and the lithium battery; the hydrogen fuel cell, NMOS transistor Q1, NMOS transistor Q8, diode D8, capacitor C2, motor, NMOS transistor Q11, NMOS transistor Q6, diode D1, NMOS transistor Q4, diode D4, lithium battery BT1, and capacitor C1 form a direct output circuit for the hydrogen fuel cell; the lithium battery BT1, capacitor C1, NMOS transistor Q5, diode D5, NMOS transistor Q2, inductor L1, NMOS transistor Q3, NMOS transistor Q8, diode D8, capacitor C2, motor, NMOS transistor Q11, and NMOS transistor Q6 form a buck-boost output circuit for the lithium battery; the motor, capacitor C2, NMOS transistor Q9, diode D9, NMOS transistor Q7, inductor L2, diode D6, diode D5, NMOS transistor Q10, lithium battery pack BT1, capacitor C1, diode D7, and diode D4 form an energy recovery circuit.

[0022] A control method for a hybrid power system of a hydrogen fuel cell and a lithium battery for an unmanned aerial vehicle, which can actively select the best circuit to supply power to the unmanned aerial vehicle according to different working conditions of the unmanned aerial vehicle. The selection basis and the on-off method of the switching transistors are as follows:

[0023] When the drone is in a state that requires high-power output, such as taking off or accelerating, the power required by the drone is 2 to 4 times that during stable flight. The hydrogen fuel cell and lithium battery matching output circuit is activated. NMOS transistor Q1, NMOS transistor Q5, and NMOS transistor Q11 are turned on, NMOS transistor Q8 remains off, and NMOS transistors Q2 and Q3 are synchronously turned on and off at high frequency and are mutually exclusive with NMOS transistor Q6 for conduction and shutdown; when NMOS transistors Q2 and Q3 are turned on and NMOS transistor Q6 is turned off, the current starts from the positive electrode of the hydrogen fuel cell and successively passes through NMOS transistor Q1, NMOS transistor Q2, inductor L1, NMOS transistor Q3, and diode D1 and finally returns to the negative electrode of the hydrogen fuel cell, as shown in Figure 2(a); when NMOS transistors Q2 and Q3 are turned off and NMOS transistor Q6 is turned on, the current in the inductor starts from inductor L1 and successively passes through diode D3, NMOS transistor Q8, diode D8, capacitor C2 and the motor, NMOS transistor Q11, NMOS transistor Q6, and diode D2 and returns to inductor L1. The current in lithium battery BT1 starts from the positive electrode of lithium battery BT1 and successively passes through NMOS transistor Q5, diode D5, NMOS transistor Q8, diode D8, capacitor C2 and the motor, NMOS transistor Q11, NMOS transistor Q6 and finally flows into the negative electrode of lithium battery BT1, as shown in Figure 2(b); when the duty cycle D of the conduction of NMOS transistors Q2 and Q3 is greater than 0.5, the hydrogen fuel cell is boosted and connected in parallel with the lithium battery pack to supply power to the motor; when the duty cycle D of the conduction of NMOS transistors Q2 and Q3 is less than 0.5, the hydrogen fuel cell is bucked and connected in parallel with the lithium battery pack to supply power to the motor; this can solve the voltage mismatch between the hydrogen fuel cell and the lithium battery caused by the change of the output voltage of the hydrogen fuel cell with the load current.

[0024] When the drone is flying stably, the required power is relatively low. At this time, the hydrogen fuel cell alone supplies power to the motor, and the hydrogen fuel cell direct output circuit is activated; NMOS transistors Q1, Q8, Q11, and Q6 are turned on; the current starts from the positive electrode of the hydrogen fuel cell and successively passes through NMOS transistor Q1, NMOS transistor Q8, diode D8, capacitor C2 and the motor, NMOS transistor Q11, NMOS transistor Q6, and diode D1 and finally returns to the negative electrode of the hydrogen fuel cell, as shown in Figure 3(a); when the SOC of the lithium battery pack is lower than 1 / 3 at this time, NMOS transistor Q4 is turned on, and the hydrogen fuel cell charges the lithium battery while supplying power to the motor; at this time, part of the current flows through NMOS transistor Q1 and then successively passes through NMOS transistor Q4, diode D4, capacitor C1 and the lithium battery pack and then flows to diode D1, as shown in Figure 3(b);

[0025] When the SOC value of the hydrogen fuel cell is lower than 1 / 3 and the battery BT1 of the lithium battery has sufficient power, the lithium battery pack BT1 supplies power to the motor, and the lithium battery buck-boost power supply circuit is turned on; the NMOS transistor Q5, the NMOS transistor Q11, and the NMOS transistor Q6 are turned on; the NMOS transistors Q2, Q3, and Q8 are turned on and off in a high-frequency mutually exclusive manner; when the NMOS transistors Q2 and Q3 are turned on and the NMOS transistor Q8 is turned off, the current starts from the positive electrode of the lithium battery BT1 and flows through the NMOS transistor Q5, the diode D5, the NMOS transistor Q2, the inductor L1, and the NMOS transistor Q3 in sequence and then returns to the negative electrode of the lithium battery BT1, as shown in Figure 4(a); when the NMOS transistors Q2 and Q3 are turned off and the NMOS transistor Q8 is turned on, the current starts from the inductor L1 and flows through the diode D3, the NMOS transistor Q8, the diode D8, the capacitor C2 and the motor, the NMOS transistor Q11, the NMOS transistor Q6, and the diode D2 in sequence and then returns to the inductor L1, as shown in Figure 4(b); when the duty cycle D of the NMOS transistors Q2 and Q3 being turned on is greater than 0.5, the boost output of the lithium battery can be achieved; when the duty cycle D of the NMOS transistors Q2 and Q3 being turned on is less than 0.5, the buck output of the lithium battery can be achieved, so as to ensure the stability of the output voltage.

[0026] A hydrogen fuel cell and lithium battery hybrid power system for an unmanned aerial vehicle can also achieve high-efficiency energy recovery. The implementation method is as follows:

[0027] When the energy recovery circuit is turned on, the NMOS transistor Q7 and the NMOS transistor Q9 are turned on, and the NMOS transistor Q10 is turned on and off at a high frequency; when the NMOS transistor Q10 is turned on, the current generated in the motor starts from the motor and flows through the NMOS transistor Q9, the diode D9, the NMOS transistor Q7, the inductor L2, the diode D6, the diode D5, and the NMOS transistor Q10 in sequence and then returns to the motor, as shown in Figure 5(a); when the NMOS transistor Q10 is turned off, the current starts from the inductor L2 and flows through the diode D6, the diode D4, the lithium battery BT1 and the capacitor C2, the diode D7, and the NMOS transistor Q7 in sequence and then returns to the inductor L2, as shown in Figure 5(b); when the duty cycle D of the NMOS transistor Q10 being turned on is greater than 0.5, the electricity generated by the motor can be boosted and used to charge the lithium battery BT1; when the duty cycle D of the NMOS transistor Q10 being turned on is less than 0.5, the electricity generated by the motor can be bucked and used to charge the lithium battery BT1, so as to ensure the stability of the charging voltage of the lithium battery and improve the charging efficiency of the lithium battery.

Claims

1. A hybrid power system of a hydrogen fuel cell and a lithium battery for a drone, comprising a set of hydrogen fuel cells and a set of lithium batteries BT1, characterized in that: The positive electrode of the hydrogen fuel cell is connected to the drain of NMOS transistor Q1, and the negative electrode of the hydrogen fuel cell is connected to the negative electrode of diode D1. The positive electrode of diode D1 is connected to the positive electrode of diode D2, the source of NMOS transistor Q3, the negative electrode of lithium battery BT1, the positive electrode of diode D7, and the source of NMOS transistor Q6. The source of NMOS transistor Q1 is connected to the drain of NMOS transistor Q2, the negative electrode of diode D3, the negative electrode of diode D5, the drain of NMOS transistor Q4, the drain of NMOS transistor Q8, and the drain of NMOS transistor Q10. The negative electrode of diode D2 is connected to the source of NMOS transistor Q2 and one end of inductor L1. The drain of NMOS transistor Q3 is connected to the positive electrode of diode D3 and the other end of inductor L1. The positive electrode of lithium battery BT1 is connected to the negative electrode of diode D4 and the drain of NMOS transistor Q5. Capacitor C1 is connected in parallel with lithium battery BT1. The negative electrode of diode D7 is connected to the drain of NMOS transistor Q6, the drain of NMOS transistor Q7, the negative electrode of diode D9, and the source of NMOS transistor Q11. The source of NMOS transistor Q5 is connected to the source of NMOS transistor Q4, the positive electrode of diode D4, the negative electrode of diode D6, and the positive electrode of diode D5. The positive electrode of diode D6 is connected to one end of inductor L2, and the other end of inductor L2 is connected to the source of NMOS transistor Q7. The positive electrode of the motor is connected to the drain of NMOS transistor Q9 and the negative electrode of diode D8. The negative electrode of the motor is connected to the source of NMOS transistor Q10 and the drain of NMOS transistor Q11. Capacitor C2 is connected in parallel with the motor. The positive electrode of diode D8 is connected to the source of NMOS transistor Q8. The positive electrode of diode D9 is connected to the source of NMOS transistor Q9.

2. The hybrid power system according to claim 1, wherein: The hydrogen fuel cell, NMOS transistor Q1, NMOS transistor Q2, inductor L1, NMOS transistor Q3, diode D1, diode D2, diode D3, NMOS transistor Q8, diode D8, capacitor C2, motor, NMOS transistor Q11, NMOS transistor Q6, lithium battery BT1, capacitor C1, NMOS transistor Q5, and diode D5 form a matching output circuit for the hydrogen fuel cell and the lithium battery; the hydrogen fuel cell, NMOS transistor Q1, NMOS transistor Q8, diode D8, capacitor C2, motor, NMOS transistor Q11, NMOS transistor Q6, diode D1, NMOS transistor Q4, diode D4, lithium battery BT1, and capacitor C1 form a direct output circuit for the hydrogen fuel cell; the lithium battery BT1, capacitor C1, NMOS transistor Q5, diode D5, NMOS transistor Q2, inductor L1, NMOS transistor Q3, NMOS transistor Q8, diode D8, capacitor C2, motor, NMOS transistor Q11, and NMOS transistor Q6 form a buck-boost output circuit for the lithium battery; the motor, capacitor C2, NMOS transistor Q9, diode D9, NMOS transistor Q7, inductor L2, diode D6, diode D5, NMOS transistor Q10, lithium battery BT1, capacitor C1, diode D7, and diode D4 form an energy recovery circuit.

3. The control method of a hydrogen fuel cell and lithium battery hybrid power system for an unmanned aerial vehicle according to claim 2, characterized in that: When the UAV needs a high-power output state, start the hydrogen fuel cell and lithium battery matching output circuit; NMOS transistor Q1, NMOS transistor Q5, and NMOS transistor Q11 are turned on, NMOS transistor Q8 remains off, and NMOS transistors Q2 and Q3 are turned on and off synchronously at high frequency and are mutually exclusive with NMOS transistor Q6 for conduction and shutdown; when NMOS transistors Q2 and Q3 are turned on and NMOS transistor Q6 is turned off, the current starts from the positive pole of the hydrogen fuel cell and passes through NMOS transistor Q1, NMOS transistor Q2, inductor L1, NMOS transistor Q3, and diode D1 in sequence and finally returns to the negative pole of the hydrogen fuel cell; when NMOS transistors Q2 and Q3 are turned off and NMOS transistor Q6 is turned on, the current in inductor L1 starts from inductor L1 and passes through diode D3, NMOS transistor Q8, diode D8, capacitor C2 and the motor, NMOS transistor Q11, NMOS transistor Q6, and diode D2 in sequence and returns to inductor L1, and the current in lithium battery BT1 passes through NMOS transistor Q5, diode D5, NMOS transistor Q8, diode D8, capacitor C2 and the motor, NMOS transistor Q11, and NMOS transistor Q6 in sequence starting from the positive pole of lithium battery BT1 and finally flows into the negative pole of lithium battery BT1; when the duty cycle D of the conduction of NMOS transistors Q2 and Q3 is greater than 0.5, the hydrogen fuel cell is boosted and connected in parallel with lithium battery BT1 to supply power to the motor; when the duty cycle D of the conduction of NMOS transistors Q2 and Q3 is less than 0.5, the hydrogen fuel cell is bucked and connected in parallel with lithium battery BT1 to supply power to the motor.

4. The control method of a hybrid power system of a hydrogen fuel cell and a lithium battery for an unmanned aerial vehicle according to claim 2, characterized in that: When the power required by the UAV is low, start the direct output circuit of the hydrogen fuel cell; NMOS transistors Q1, Q8, Q11, and Q6 are turned on; the current starts from the positive pole of the hydrogen fuel cell and passes through NMOS transistor Q1, NMOS transistor Q8, diode D8, capacitor C2 and the motor, NMOS transistor Q11, NMOS transistor Q6, and diode D1 in sequence and finally returns to the negative pole of the hydrogen fuel cell; when the SOC of lithium battery BT1 is lower than a certain value at this time, NMOS transistor Q4 is turned on and the hydrogen fuel cell charges lithium battery BT1 while supplying power to the motor, and a part of the current passes through NMOS transistor Q4, diode D4, capacitor C1, and lithium battery BT1 in sequence after flowing through NMOS transistor Q1 and then flows to diode D1.

5. The control method of a hybrid power system of a hydrogen fuel cell and a lithium battery for an unmanned aerial vehicle according to claim 2, characterized in that: When the SOC value of the hydrogen fuel cell is lower than a certain value and the SOC value of the lithium battery BT1 is higher than a certain value, the lithium battery BT1 supplies power to the motor, the lithium battery buck-boost power supply circuit is turned on, and the NMOS transistors Q5, Q11, and Q6 are turned on; the NMOS transistors Q2, Q3, and Q8 are turned on and off mutually at high frequency; when the NMOS transistors Q2 and Q3 are turned on and the NMOS transistor Q8 is turned off, the current starts from the positive electrode of the lithium battery BT1 and flows through the NMOS transistor Q5, the diode D5, the NMOS transistor Q2, the inductor L1, and the NMOS transistor Q3 in sequence and then returns to the negative electrode of the lithium battery BT1; when the NMOS transistors Q2 and Q3 are turned off and the NMOS transistor Q8 is turned on, the current starts from the inductor L1 and flows through the diode D3, the NMOS transistor Q8, the diode D8, the capacitor C2 and the motor, the NMOS transistors Q11 and Q6, and the diode D2 in sequence and then returns to the inductor L1; when the duty cycle D of the NMOS transistors Q2 and Q3 being turned on is greater than 0.5, the lithium battery boost output is realized; when the duty cycle D of the NMOS transistors Q2 and Q3 being turned on is less than 0.5, the lithium battery buck output is realized.

6. The control method of a hybrid power system of a hydrogen fuel cell and a lithium battery for an unmanned aerial vehicle according to claim 2, characterized in that: When the energy recovery circuit is turned on, the NMOS transistors Q7 and Q9 are turned on, and the NMOS transistor Q10 is turned on and off at high frequency; when the NMOS transistor Q10 is turned on, the current generated in the motor starts from the motor and flows through the NMOS transistor Q9, the diode D9, the NMOS transistor Q7, the inductor L2, the diode D6, the diode D5, and the NMOS transistor Q10 in sequence and then returns to the motor; when the NMOS transistor Q10 is turned off, the current starts from the inductor L2 and flows through the diode D6, the diode D4, the lithium battery BT1 and the capacitor C2, the diode D7, and the NMOS transistor Q7 in sequence and then returns to the inductor L2; when the duty cycle D of the NMOS transistor Q10 being turned on is greater than 0.5, the electricity generated by the motor is boosted and then used to charge the lithium battery BT1, and when the duty cycle D of the NMOS transistor Q10 being turned on is less than 0.5, the electricity generated by the motor is bucked and then used to charge the lithium battery BT1.

Images