A direct methanol fuel cell control system for unmanned aerial vehicles

Abstract

This invention discloses a direct methanol fuel cell control system for unmanned aerial vehicles (UAVs), belonging to the field of fuel cell and UAV energy management technology. The invention includes a direct methanol fuel cell stack, a lithium battery pack, peripheral accessory subsystems, a power management controller, and a power hybrid and charging management circuit. The power hybrid and charging management circuit uses an ideal diode controller to achieve ultra-low-loss parallel connection and automatic seamless switching between the fuel cell and lithium battery to the power bus; the power management controller executes an adaptive charging control strategy, dynamically controlling charging on / off and current magnitude based on multi-parameter feedback of voltage and temperature; simultaneously, it executes a peripheral accessory collaborative control strategy, precisely adjusting accessory power according to the stack operating conditions. This invention solves the problems of low efficiency, rudimentary charging management, and high accessory energy consumption in existing technologies, significantly improving UAV endurance, reliability, and overall system efficiency.

Description

Technical Field

[0001] This invention relates to the field of fuel cell and drone energy management technology, specifically to a direct methanol fuel cell control system for drones. Background Technology

[0002] Fixed-wing drones have extremely high requirements for the weight, efficiency, and endurance of their power systems. Direct methanol fuel cells (DMFCs) are an ideal candidate for airborne power sources due to their high energy density. However, DMFCs have a slow dynamic response and typically need to be combined with high-power-density lithium batteries to form a hybrid power system to meet the peak power demands of drones during takeoff and climb.

[0003] Existing hybrid power supply control schemes have many shortcomings. For example, Chinese invention patent CN112277733A switches power supplies by monitoring motor speed. This method is rather crude, failing to consider the working state of the fuel cell stack itself and neglecting optimized control of peripheral accessories, resulting in low overall system efficiency. Furthermore, its hybrid power supply often uses power transistors such as MOSFETs (Metal-Oxide-Semiconductor Field-Effect Transistors), which suffer from high conduction losses (efficiency typically below 90%) and severe heat generation.

[0004] In terms of charging management, existing solutions often employ a simple voltage comparison method or begin charging immediately after the fuel cell starts up. This approach is prone to causing system voltage collapse when the stack is in poor condition (such as low temperature or low load), or to accelerating the degradation of the stack life due to improper charging current.

[0005] Therefore, there is an urgent need in this field for a control system that can achieve efficient energy mixing, intelligent charging management, and deep coordination with the stack status, in order to comprehensively improve the performance and reliability of UAV power systems. Summary of the Invention

[0006] The purpose of this invention is to overcome the shortcomings of the prior art and provide a system-level optimized direct methanol fuel cell control system. This system can achieve ultra-low energy loss mixing and seamless switching, safe and adaptive intelligent charging management, and precise coordinated control of peripheral accessories.

[0007] To achieve the above objectives, the technical solution adopted by the present invention is as follows: This invention provides a direct methanol fuel cell control system for unmanned aerial vehicles (UAVs), including a direct methanol fuel cell stack, a lithium battery pack, peripheral accessory subsystems, a power management controller, and a power hybridization and charging management circuit. The direct methanol fuel cell stack and the lithium battery pack are connected in parallel to a power bus via a power hybridization and charging management circuit. The power bus is used to connect the drone payload. The power management controller is connected to the direct methanol fuel cell stack, lithium battery pack and peripheral accessory subsystems through a sensor network to collect status monitoring signals from the direct methanol fuel cell stack, lithium battery pack and peripheral accessory subsystems; The power management controller generates a first operating state parameter based on signals collected from the direct methanol fuel cell stack and peripheral accessory subsystems, and generates a first control command based on the first operating state parameter. The peripheral accessory subsystem executes reactant supply and thermal management operations according to the first control command; The power management controller generates a second operating state parameter based on signals collected from the direct methanol fuel cell stack and lithium battery pack, and generates a second control command based on the second operating state parameter. The power hybrid and charging management circuit is connected to the power management controller, the direct methanol fuel cell stack, and the lithium battery pack. The power hybrid and charging management circuit includes a hybrid power supply unit and an intelligent charging unit. The hybrid power supply unit is a hybrid circuit based on an ideal diode controller, used to manage the power output of the direct methanol fuel cell stack and the lithium battery pack to the drone payload. The intelligent charging unit controls the charging process of the direct methanol fuel cell stack to the lithium battery pack based on a second control command.

[0008] Furthermore, the peripheral accessory subsystem includes a reactant supply unit, a thermal management unit, and an auxiliary management unit; The reactant supply unit includes an air intake pump for supplying air, a methanol fuel pump for supplying fuel, and a methanol circulation pump for circulating fuel. The thermal management unit includes a cooling water pump for circulating coolant, a radiator for dissipating heat, and a cooling fan for providing forced cooling airflow to the radiator. The auxiliary management unit includes a gas-liquid separator for separating reaction products.

[0009] Furthermore, based on the output current and temperature of the direct methanol fuel cell stack in the first operating state parameters, the power management controller executes the peripheral accessory cooperative control strategy and outputs the first control command for adjusting power to the peripheral accessory subsystem: The peripheral accessory coordinated control strategy includes: The power management controller acquires the output current and temperature of the direct methanol fuel cell stack in real time. Based on the acquired output current, the power management controller queries the preset mapping relationship between current-air flow and current-fuel flow, and generates the first control command to adjust the power of the intake pump and methanol fuel pump. The power management controller compares the real-time temperature with a preset target temperature range and generates a first control command to adjust the speed of the cooling water pump or cooling fan.

[0010] Furthermore, the hybrid power supply unit includes a first ideal diode control circuit and a second ideal diode control circuit; The first ideal diode control circuit is composed of a first ideal diode controller driving a first P-MOSFET. The source of the first P-MOSFET is directly connected to the output terminal of the methanol fuel cell stack, and the drain is connected to the power bus. The second ideal diode control circuit consists of a second ideal diode controller driving a second P-MOSFET; the source of the second P-MOSFET is connected to the output terminal of the lithium battery pack, and the drain is connected to the power bus. A P-MOSFET is a P-channel metal-oxide-semiconductor field-effect transistor, a specific type of MOSFET.

[0011] The first ideal diode controller / second ideal diode controller automatically controls the on / off state of the first P-MOSFET / second P-MOSFET by monitoring the source-drain voltage difference of the first P-MOSFET / second P-MOSFET in real time: when the source voltage of the first P-MOSFET / second P-MOSFET is higher than its drain voltage, the first ideal diode controller / second ideal diode controller drives the first P-MOSFET / second P-MOSFET to enter the conduction state, and vice versa. When the first P-MOSFET is in the on state, the direct methanol fuel cell stack supplies power to the power bus; when the second P-MOSFET is in the on state, the lithium battery pack supplies power to the power bus.

[0012] Furthermore, based on the voltage and temperature of the direct methanol fuel cell stack, lithium battery pack, and power bus in the second operating state parameters, the power management controller executes an adaptive charging control strategy and outputs a second control command to the intelligent charging unit, including a charging on / off command and a charging current setting command.

[0013] Furthermore, the intelligent charging unit includes a charging switch and a current control circuit, and the direct methanol fuel cell stack and lithium battery pack form a charging circuit. The charging switch is connected in series in the charging circuit. The control terminal of the charging switch is connected to the power management controller and receives the charging on / off command sent by the power management controller according to the adaptive charging control strategy. The current control circuit is connected in series in the charging circuit and is located between the charging switch and the lithium battery pack. The control terminal of the current control circuit is connected to the power management controller and receives the charging current setting command sent by the power management controller according to the adaptive charging control strategy.

[0014] Furthermore, receiving charging on / off commands according to the adaptive charging control strategy includes the following operations: The power management controller continuously monitors the voltage and temperature of the direct methanol fuel cell stack and lithium battery pack through a sensor network, and makes judgments based on the charging enable conditions in the adaptive charging control strategy. When all charging enable conditions are met, the power management controller outputs a charging start command to the charging switch; when any charging enable condition is no longer met, it immediately outputs a charging stop command.

[0015] Furthermore, the charging enable conditions include: The voltage of the direct methanol fuel cell stack is higher than the first voltage threshold. The voltage of the lithium battery pack is below the second voltage threshold. The temperature of the direct methanol fuel cell stack is below the first temperature threshold. The temperature of the lithium battery pack is below the second temperature threshold.

[0016] Furthermore, receiving the charging current setting command sent by the power management controller according to the adaptive charging control strategy includes the following operations: With the charging circuit connected, the charging process begins with an initial current value. The power management controller continuously monitors the voltage of the direct methanol fuel cell stack and determines whether it is higher than the third voltage threshold, which is the sum of the first voltage threshold and a hysteresis voltage. Based on the judgment result, the power management controller dynamically calculates the target charging current value through an adaptive charging control strategy and generates the corresponding charging current setting command. The current control circuit receives and responds to the charging current setting command, and precisely adjusts the actual charging current value to the target charging current value.

[0017] Furthermore, the dynamic calculation of the target charging current value includes: If the voltage of the direct methanol fuel cell stack is higher than the third voltage threshold, the target charging current value is controlled to increase at a preset rate. If the voltage of the direct methanol fuel cell stack falls back to the range formed by the first voltage threshold and the third voltage threshold, the target charging current value will be maintained stable.

[0018] Compared with the prior art, the present invention has the following beneficial effects: 1. This invention employs a hybrid power supply circuit based on an ideal diode controller, replacing the traditional power transistor solution. This minimizes losses during energy mixing and switching, achieving an extremely high power supply efficiency exceeding 98%. This directly reduces unnecessary heat dissipation and allows more energy to be used for flight, significantly extending endurance.

[0019] 2. This invention achieves precise on-demand control of accessories such as the intake pump, fuel pump, and cooling system through a peripheral accessory coordinated control strategy, ensuring that their power consumption always matches the actual needs of the fuel cell stack. This completely changes the traditional fixed power operation mode, eliminates unnecessary accessory energy consumption, and further improves the overall range of the unit.

[0020] 3. This invention employs an adaptive charging control strategy based on multi-parameter feedback of voltage and temperature. This strategy dynamically mines and utilizes the instantaneous surplus power of the fuel cell for charging, achieving full utilization and adaptive use of the fuel cell's surplus power, significantly improving charging efficiency and speed. Simultaneously, the adaptive charging control strategy, through multiple real-time protection conditions (voltage, temperature) and a voltage feedback-based current increment algorithm, avoids safety issues such as system voltage collapse or fuel cell lifespan degradation caused by charging when the fuel cell stack is in poor condition, ensuring a fully efficient and safe charging process.

[0021] 4. The automatic switching mechanism of the hybrid power supply unit in this invention achieves microsecond-level, seamless switching between the fuel cell and the lithium battery, ensuring absolute continuity of power supply for the UAV during periods of drastic load fluctuations (such as takeoff and climb), and avoiding the risk of instantaneous power outages caused by power switching. The hybrid system, composed of dual power sources of fuel cells and lithium batteries, provides natural redundancy backup; the failure of a single power source will not cause the UAV to become inoperable, greatly improving the system's reliability and survivability.

[0022] 5. This invention deeply integrates hybrid power supply, intelligent charging, and peripheral device collaborative control, forming a unified and optimized whole. The power management controller coordinates global information and realizes cross-unit collaborative decision-making, enabling the entire system to operate as an intelligent living entity, with comprehensive performance far exceeding the simple sum of the performance of individual components. Attached Figure Description

[0023] Figure 1 This is a system block diagram of the present invention. Detailed Implementation

[0024] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings. Obviously, the described embodiments are merely some embodiments of this invention, and not all embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of this invention without creative effort are within the scope of protection of this invention.

[0025] In the description of this invention, it should be noted that the terms "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing the invention and for simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the invention. Furthermore, the terms "first," "second," and "third," etc., are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0026] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; of course, they can also refer to a mechanical connection or an electrical connection; furthermore, they can refer to a direct connection, an indirect connection through an intermediate medium, or a connection within two components. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0027] like Figure 1 As shown, this invention provides a direct methanol fuel cell control system for unmanned aerial vehicles (UAVs), characterized by comprising a direct methanol fuel cell stack, a lithium battery pack, peripheral accessory subsystems, a power management controller, and a power hybrid and charging management circuit. This invention deeply integrates hybrid power supply, intelligent charging, and peripheral device collaborative control, forming a unified and optimized whole. The power management controller coordinates global information, enabling cross-unit collaborative decision-making, allowing the entire system to operate as an intelligent living entity.

[0028] This invention connects a direct methanol fuel cell stack and a lithium battery pack in parallel to a power bus via a power hybrid and charging management circuit. This power bus is used to connect the drone payload. The power hybrid and charging management circuit automatically switches the connection relationship between the direct methanol fuel cell stack, the lithium battery pack, and the power bus based on the real-time system status, thereby achieving power supply switching and energy management for the drone payload. Preferably, the power management controller is an embedded microcontroller. More preferably, the embedded microcontroller uses a microcontroller unit with an ARM Cortex-M series core integrating advanced timers, a high-precision analog-to-digital converter, and a CAN bus controller.

[0029] The power hybrid and charging management circuit of this invention includes a hybrid power supply unit and an intelligent charging unit. The hybrid power supply unit, as the core energy dispatch hub of this system, manages the power output of the direct methanol fuel cell stack and lithium battery pack to the UAV payload. It is implemented using an architecture based on a dedicated ideal diode controller. Specifically, the hybrid power supply unit includes a first ideal diode control circuit and a second ideal diode control circuit. The first ideal diode control circuit consists of a first ideal diode controller (U1) driving a first P-MOSFET (Q1), with the source of the first P-MOSFET (Q1) connected to the output terminal of the direct methanol fuel cell stack and the drain connected to the power bus. The second ideal diode control circuit consists of a second ideal diode controller (U2) driving a second P-MOSFET (Q2), with the source of the second P-MOSFET (Q1) connected to the output terminal of the lithium battery pack and the drain connected to the power bus.

[0030] The first ideal diode controller (U1) continuously monitors the voltage difference between the source and drain of Q1. When the source voltage of Q1 is higher than its drain voltage, i.e., the fuel cell voltage is higher than the power bus voltage, U1 determines it to be forward biased and immediately drives Q1 into a fully conducting state, at which point the fuel cell supplies power to the power bus. Conversely, when the source voltage of Q1 is lower than its drain voltage, i.e., the power bus voltage is higher than the fuel cell voltage, U1 determines it to be reverse biased and immediately turns off Q1, effectively preventing current backflow.

[0031] Similarly, the second ideal diode controller (U2) controls the switching on and off of Q2 to achieve automatic connection and isolation of the lithium battery pack.

[0032] Preferably, the first ideal diode controller (U1) and the second ideal diode controller (U2) adopt Linear Technology LTC4417. Traditional solutions use MOSFETs for active switching control, resulting in high conduction losses, significant heat generation, and system efficiency typically below 90%. This invention employs an ideal diode solution, where the MOSFET has extremely low equivalent resistance during conduction and a forward voltage drop in the millivolt range, achieving near-ideal unidirectional conductivity characteristics. Hybrid power supply efficiency can be increased to over 98%, significantly reducing heat loss and improving system power density and reliability.

[0033] The invention also includes a power management controller and a peripheral accessory subsystem. The power management controller collects voltage, current, and temperature parameters of the fuel cell stack, lithium battery, and power bus in real time through a sensor network, and executes peripheral accessory collaborative control strategies and adaptive charging control strategies.

[0034] Preferably, the peripheral accessory subsystem includes a reactant supply unit, a thermal management unit, and an auxiliary management unit. The reactant supply unit includes an air intake pump for supplying air, a methanol fuel pump for supplying fuel, and a methanol circulation pump for circulating fuel. The thermal management unit includes a cooling water pump for circulating coolant, a radiator for dissipating heat, and a cooling fan for providing forced cooling airflow to the radiator. The auxiliary management unit includes a gas-liquid separator for separating reaction products. The reactant supply unit is responsible for precisely delivering fuel and oxidant. The air intake pump is used to force ambient air (oxygen source) into the cathode of the fuel cell stack at a specific pressure and flow rate; the air intake pump is an adjustable-speed blower or air pump. The methanol fuel pump is used to draw a high-concentration methanol solution from the fuel tank and inject it into the anode circulation loop. The methanol circulation pump is used to drive the continuous circulation of fuel on the anode side, ensuring uniform fuel concentration and timely removal of reaction products (such as carbon dioxide bubbles) and generated water. The thermal management unit is responsible for regulating the operating temperature of the fuel cell stack, ensuring it operates within the optimal temperature window. A cooling water pump propels coolant through cooling channels inside the fuel cell stack, absorbing the heat generated by the reaction. The high-temperature coolant then flows through a radiator, where a cooling fan forces the heat out into the environment. An auxiliary management unit handles reaction byproducts. A gas-liquid separator is installed in the anode outlet circuit of the fuel cell stack to separate carbon dioxide gas from the liquid methanol-water solution in the anode outlet mixture. Further, the separated carbon dioxide gas is discharged from the system, while unreacted methanol and generated water are returned to the circulation loop and pumped back into the fuel cell stack reaction by a methanol circulation pump, significantly improving fuel efficiency.

[0035] The power management controller is connected to the direct methanol fuel cell stack, lithium battery pack, and peripheral accessory subsystems via a sensor network to collect status monitoring signals from the direct methanol fuel cell stack, lithium battery pack, and peripheral accessory subsystems.

[0036] Preferably, the sensor network includes multiple voltage sensors, current sensors, temperature sensors, and a fluid monitoring sensor group installed in the peripheral accessory subsystem. The voltage sensors are connected in parallel to the output terminals of the direct methanol fuel cell stack, the lithium battery pack, and the power bus, respectively, for real-time monitoring of the voltage of the direct methanol fuel cell stack, the lithium battery pack, and the power bus. The current sensors are connected in series in the output circuits of the direct methanol fuel cell stack, the lithium battery pack, and the total output circuit of the power bus, respectively, for real-time monitoring of the current of the direct methanol fuel cell stack, the lithium battery pack, and the power bus. The temperature sensors are installed on the heat sinks of the direct methanol fuel cell stack, the lithium battery pack, and the peripheral accessory subsystem, respectively, for real-time sensing of the temperature of the direct methanol fuel cell stack, the lithium battery pack, and the heat sink. The fluid monitoring sensor group includes at least one of a flow meter for monitoring fuel flow, a level gauge for monitoring fuel level, and a concentration sensor for detecting methanol concentration. The signal output terminals of the voltage sensors, current sensors, temperature sensors, and the fluid monitoring sensor group are all connected to the power management controller. More preferably, the current sensor is a Hall current sensor or a current detection circuit based on a sampling resistor and a differential amplifier. More preferably, the temperature sensor is a thermistor or a digital temperature sensor.

[0037] This invention achieves precise on-demand control of accessories such as the air pump, fuel pump, and cooling system through a peripheral accessory coordinated control strategy, ensuring that their power consumption always matches the actual needs of the fuel cell stack. This completely changes the traditional fixed power operation mode, eliminates unnecessary accessory energy consumption, and further improves the overall range of the unit.

[0038] The peripheral accessory coordinated control strategy is executed by the power management controller: Based on the output current and temperature of the direct methanol fuel cell stack in the first operating state parameters, the power management controller executes the peripheral accessory coordinated control strategy and outputs the first control command for adjusting the power to the peripheral accessory subsystem.

[0039] In one embodiment, the peripheral accessory collaborative control strategy is implemented as follows: S101. Status Acquisition: The power management controller acquires the output current and temperature of the direct methanol fuel cell stack in real time.

[0040] S102. Reactant supply control: The power management controller queries the preset mapping relationship between current-air flow rate and current-fuel flow rate based on the acquired output current, obtains the corresponding target flow rate value, converts the target flow rate value into the corresponding pulse width modulation signal, and outputs it as the first control command to the intake pump and methanol fuel pump to adjust the power of the intake pump and methanol fuel pump.

[0041] S103. Thermal Management Control: The power management controller will acquire the temperature T in real time. stack With a preset target temperature range ([T) low T high The values ​​are compared when the real-time temperature T is obtained. stack <Lower limit T within the target temperature range low At that time, control commands are generated to reduce the cooling water pump speed, radiator power, or shut down the cooling fan, when the real-time temperature T is obtained. stack Upper limit T within the target temperature range high At that time, control commands are generated to increase the speed of the cooling pump or the cooling fan.

[0042] This invention also achieves intelligent and precise management of the charging process from the direct methanol fuel cell stack to the lithium battery pack through an adaptive charging control strategy. This ensures that the charging behavior always matches the real-time power generation capacity of the stack and the system safety status, completely changing the traditional fixed current or simple switching charging mode. It eliminates system risks and energy waste caused by crude charging management, and further improves the overall range and system reliability.

[0043] The adaptive charging control strategy is executed by the power management controller: Based on the voltage and temperature of the direct methanol fuel cell stack, lithium battery pack and power bus in the second operating state parameters, the power management controller executes the adaptive charging control strategy and outputs a second control command to the intelligent charging unit, including charging on / off command and charging current setting command.

[0044] The intelligent charging unit includes a charging switch and a current control circuit, and the direct methanol fuel cell stack and lithium battery pack form a charging circuit. The charging switch is connected in series in the charging circuit. The control terminal of the charging switch is connected to the power management controller and receives the charging on / off command sent by the power management controller according to the adaptive charging control strategy. The current control circuit is connected in series in the charging circuit and is located between the charging switch and the lithium battery pack. The control terminal of the current control circuit is connected to the power management controller and receives the charging current setting command sent by the power management controller according to the adaptive charging control strategy.

[0045] Preferably, the charging switch is a MOSFET (Q3), the charging current setting command is a pulse width modulation signal or an analog voltage signal, and the current control circuit uses a switching power converter or a linear current source with closed-loop feedback control based on the pulse width modulation signal or the analog voltage signal. More preferably, the current control circuit is implemented using a controllable current source or a Buck converter circuit with pulse width modulation control.

[0046] In one embodiment, the adaptive charging control strategy is implemented as follows: S201. System Status Monitoring: The power management controller continuously acquires the output voltage (V) of the direct methanol fuel cell stack through its integrated analog-to-digital converter. fc ) and temperature (T) fc ), the voltage of the lithium battery pack (V) Li ) and temperature (T) Li ); S202. Charging Safety Enable Judgment: The power management controller compares the collected parameters with preset safety thresholds to determine whether all of the following conditions are met simultaneously: V fc First voltage threshold; V Li <Second voltage threshold; T fc <First temperature threshold; T Li <Second temperature threshold.

[0047] If all conditions are met, proceed to step S103; if any condition is not met, immediately jump to step S107 and shut down the charging circuit.

[0048] S203. Start charging: The power management controller sends a charging enable command to the power hybrid and charging management circuit, closes the charging switch (Q3), and starts charging with a preset safe initial current value (e.g., 0.5A).

[0049] S204. Dynamic adjustment of charging current: During the charging process, the power management controller continuously monitors V. fc It is then compared with a third voltage threshold (which is the sum of the first voltage threshold and a hysteresis voltage): If V fc The third voltage threshold indicates that the fuel cell stack has excess power generation capacity. The power management controller then increases the target charging current value at a preset rate (such as 0.1 A / s) until the maximum charging current limit allowed by the system is reached.

[0050] If V fc If the voltage drops back to the range of [first voltage threshold, third voltage threshold], the current charging current value will be maintained.

[0051] S205. Parallel monitoring of charging safety conditions: During the charging process (including steps S103 and S104), the power management controller initiates a real-time safety monitoring thread that runs in parallel with the charging current regulation.

[0052] S206. Real-time safety status judgment: In the monitoring thread, the power management controller continuously and rapidly acquires system parameters and determines whether all the charging enable conditions defined in step S202 are still met.

[0053] S207. Charging circuit rapid shutdown: Once the judgment result of step S206 is negative, that is, any safety condition is violated, the power management controller will immediately and unconditionally perform the following operation: (1) Switch the charging enable signal from an active state to an inactive state; (2). Drive the charging switch (Q3) from the on state to the off state, forcibly terminate the charging process, and reduce the charging current to zero.

[0054] Existing technologies often employ fixed-current charging or simple voltage comparison methods, failing to consider the real-time load-carrying capacity of the fuel cell stack and the system's thermal state. This can easily lead to low charging efficiency or system risks. The adaptive charging strategy of this invention utilizes a voltage feedback-based current increment mechanism to dynamically tap into the fuel cell stack's excess power, thereby increasing charging speed. Simultaneously, through multiple, real-time coupled judgments of voltage and temperature, a robust safety protection system is established, significantly improving the safety of the charging process and the overall reliability of the system.

[0055] This invention achieves complementary advantages between fuel cells and lithium batteries (fuel cells provide long-lasting flight, while lithium batteries provide peak power and start-up capability), and all components operate in the most efficient manner under the intelligent scheduling of the power management controller, thereby achieving the ultimate goal of improving the drone's flight endurance, reliability, and system efficiency.

[0056] In one embodiment, the specific operation of a drone using a direct methanol fuel cell control system provided by the present invention is as follows: S1. System Startup and Basic Power Supply: The drone is powered on and started. At this time, the fuel cell stack is cold and cannot output power. The lithium battery pack, as the only available power source, supplies power to the entire drone system (flight controller, motors, sensors, and the power management controller itself) through the hybrid power supply unit in the power hybrid and charging management circuit. After receiving power, the power management controller begins to work and first starts the peripheral accessory subsystems: driving the air intake pump to supply air to the stack; driving the methanol fuel pump to supply fuel to the stack; and starting the cooling water pump for initial circulation. After the reactants are supplied, the fuel cell stack begins to undergo electrochemical reactions, and the output voltage gradually builds up.

[0057] S2. Intelligent Switching and Hybrid Power Supply: When the output voltage of the fuel cell stack stabilizes and rises above the power bus voltage, the ideal diode controller in the power hybrid and charging management circuit detects this voltage difference. The ideal diode controller on the fuel cell side automatically turns on its controlled P-MOSFET (Q1) completely. Due to the extremely low on-resistance of this path, current flows naturally and seamlessly from the fuel cell side to the power bus, taking over as the main power source for the system. Simultaneously, the ideal diode controller on the lithium battery side automatically turns off its P-MOSFET (Q2) because its voltage is lower than the power bus voltage. The lithium battery pack is then disconnected from the power bus, transitioning from a discharging state to a standby state.

[0058] S3. Adaptive Operation and Cooperative Control: The power management controller continuously monitors V. fc V Li T fc T Li When all safety conditions are met simultaneously (e.g., V) fc > 25V, V Li < 24V, T fc < 80°C, T Li When the temperature is below 70°C, the power management controller enables the intelligent charging unit, closes the charging switch (Q3), and begins charging the lithium battery. During charging, the power management controller dynamically adjusts the charging current. If V is detected... fc If the voltage is significantly higher than the startup threshold (e.g., > 25.5V), it indicates that the battery stack currently has excess power generation capacity, and the power management controller will increase the charging current at a certain rate to charge the lithium battery more quickly; if V fc A drop in current indicates increased load demand or decreased fuel cell capacity. The power management controller will maintain or reduce the charging current to ensure absolute priority and stability in powering the main load of the drone.

[0059] S4. Peripheral Accessory Co-control: The power management controller reads the fuel cell stack output current and dynamically adjusts the speed / flow rate of the intake pump and methanol fuel pump by querying a preset current-flow MAP. The power management controller also dynamically controls the cooling water pump and cooling fan based on the fuel cell stack temperature.

[0060] Specifically, when the drone motor suddenly accelerates, causing a surge in power demand and a momentary drop in fuel cell voltage: the power bus voltage subsequently decreases, and the second ideal diode controller (U2) on the lithium battery side instantly detects that the source voltage of Q2 is higher than the drain voltage, immediately turning on Q2. At this time, both the fuel cell and the lithium battery simultaneously supply power to the power bus to handle the peak power. When the load returns to normal and the fuel cell voltage recovers, the system automatically switches back to the state where the fuel cell supplies power alone. The entire process is automatic, seamless, and uninterrupted.

[0061] Preferably, the power management controller can also work with the UAV flight control system to obtain the real-time total power demand from the flight control system or by calculating the power bus parameters, and manage the working status of the hybrid power supply unit accordingly.

[0062] Obtaining real-time total power demand from the flight control system specifically involves the power management controller establishing a communication link with the UAV flight control system via its integrated CAN or UART communication interface. Based on the current flight phase (e.g., hovering, climb, cruise, landing) and flight commands (e.g., acceleration), the flight control system sends the expected total power demand or corresponding power level commands to the power management controller through this communication link. Calculating the real-time total power demand by analyzing the power bus parameters specifically involves the power management controller monitoring the voltage (V) of the power bus. bus ) and total output current (I bus According to the formula P = V bus *I bus The system's total power consumption is calculated in real time. By performing short-term trend analysis on this power value (such as calculating its first derivative), future changes in power demand can be predicted.

[0063] After obtaining the real-time total power demand, the power management controller manages the operating status of the hybrid power supply unit accordingly, including: Anticipation and preparation: When peak power demand is predicted (such as when it is about to climb), the power management controller can ensure that the lithium battery pack is in an immediate responsive state, avoiding the impact on the drone's power due to the switching delay of the hybrid power supply unit.

[0064] Mode guidance: During the cruise phase when power demand is low, the power management controller guides the system to prioritize the use of fuel cells for power supply by adjusting relevant parameters, so that the system operates in the most efficient operating range.

[0065] This invention achieves forward-looking and proactive management of the hybrid power supply unit by introducing predictive information from the flight control system and local power calculation, enabling the energy system to anticipate flight intentions, thereby achieving better power response speed and overall energy distribution efficiency.

[0066] Finally, it should be noted that the above embodiments are merely preferred embodiments of the present invention used to illustrate the technical solutions of the present invention, and are not intended to limit the invention, nor are they intended to limit the patent scope of the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein. These modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention. That is to say, any changes or refinements made to the main design concept and spirit of the present invention that are not of substantial significance, but whose technical problems are still consistent with the present invention, should be included within the protection scope of the present invention. In addition, the direct or indirect application of the technical solutions of the present invention to other related technical fields are similarly included within the patent protection scope of the present invention.

Claims

1. A direct methanol fuel cell control system for unmanned aerial vehicles (UAVs), characterized in that, It includes a direct methanol fuel cell stack, a lithium battery pack, peripheral accessory subsystems, a power management controller, and a power hybrid and charging management circuit. The direct methanol fuel cell stack and the lithium battery pack are connected in parallel to a power bus via a power hybridization and charging management circuit. The power bus is used to connect the drone payload. The power management controller is connected to the direct methanol fuel cell stack, lithium battery pack and peripheral accessory subsystems through a sensor network to collect status monitoring signals from the direct methanol fuel cell stack, lithium battery pack and peripheral accessory subsystems; The power management controller generates a first operating state parameter based on signals collected from the direct methanol fuel cell stack and peripheral accessory subsystems, and generates a first control command based on the first operating state parameter. The peripheral accessory subsystem executes reactant supply and thermal management operations according to the first control command; The power management controller generates a second operating state parameter based on signals collected from the direct methanol fuel cell stack and lithium battery pack, and generates a second control command based on the second operating state parameter. The power hybrid and charging management circuit is connected to the power management controller, the direct methanol fuel cell stack, and the lithium battery pack. The power hybrid and charging management circuit includes a hybrid power supply unit and an intelligent charging unit. The hybrid power supply unit is a hybrid circuit based on an ideal diode controller, which is used to manage the power output of the direct methanol fuel cell stack and the lithium battery pack to the drone payload. The intelligent charging unit controls the charging process of the direct methanol fuel cell stack to the lithium battery pack based on a second control command. Based on the voltage and temperature of the direct methanol fuel cell stack, lithium battery pack and power bus in the second operating state parameters, the power management controller executes an adaptive charging control strategy and outputs a second control command to the intelligent charging unit, including a charging on / off command and a charging current setting command. The intelligent charging unit includes a charging switch and a current control circuit, and the direct methanol fuel cell stack and lithium battery pack form a charging circuit. The charging switch is connected in series in the charging circuit. The control terminal of the charging switch is connected to the power management controller and receives the charging on / off command sent by the power management controller according to the adaptive charging control strategy. The current control circuit is connected in series in the charging circuit and is located between the charging switch and the lithium battery pack. The control terminal of the current control circuit is connected to the power management controller and receives the charging current setting command sent by the power management controller according to the adaptive charging control strategy. The following operations are performed when receiving charging on / off commands according to the adaptive charging control strategy: The power management controller continuously monitors the voltage and temperature of the direct methanol fuel cell stack and lithium battery pack through a sensor network, and makes judgments based on the charging enable conditions in the adaptive charging control strategy. When all charging enable conditions are met, the power management controller outputs a charging start command to the charging switch; when any charging enable condition is no longer met, it immediately outputs a charging stop command. Charging enable conditions include: The voltage of the direct methanol fuel cell stack is higher than the first voltage threshold. The voltage of the lithium battery pack is below the second voltage threshold. The temperature of the direct methanol fuel cell stack is below the first temperature threshold. The temperature of the lithium battery pack is below the second temperature threshold. Receiving charging current setting instructions from the power management controller according to the adaptive charging control strategy includes the following operations: With the charging circuit connected, the charging process begins with an initial current value. The power management controller continuously monitors the voltage of the direct methanol fuel cell stack and determines whether it is higher than the third voltage threshold, which is the sum of the first voltage threshold and a hysteresis voltage. Based on the judgment result, the power management controller dynamically calculates the target charging current value through an adaptive charging control strategy and generates the corresponding charging current setting command. The current control circuit receives and responds to the charging current setting command, and precisely adjusts the actual charging current value to the target charging current value. The dynamic calculation of the target charging current value includes: If the voltage of the direct methanol fuel cell stack is higher than the third voltage threshold, the target charging current value is controlled to increase at a preset rate. If the voltage of the direct methanol fuel cell stack falls back to the range formed by the first voltage threshold and the third voltage threshold, the target charging current value will be maintained stable.

2. The direct methanol fuel cell control system for unmanned aerial vehicles according to claim 1, characterized in that, The peripheral accessory subsystem includes a reactant supply unit, a thermal management unit, and an auxiliary management unit; The reactant supply unit includes an air intake pump for supplying air, a methanol fuel pump for supplying fuel, and a methanol circulation pump for circulating fuel. The thermal management unit includes a cooling water pump for circulating coolant, a radiator for dissipating heat, and a cooling fan for providing forced cooling airflow to the radiator. The auxiliary management unit includes a gas-liquid separator for separating reaction products.

3. A direct methanol fuel cell control system for unmanned aerial vehicles according to claim 2, characterized in that, Based on the output current and temperature of the direct methanol fuel cell stack in the first operating state parameters, the power management controller executes the peripheral accessory cooperative control strategy and outputs the first control command for adjusting power to the peripheral accessory subsystem: The peripheral accessory coordinated control strategy includes: The power management controller acquires the output current and temperature of the direct methanol fuel cell stack in real time. Based on the acquired output current, the power management controller queries the preset mapping relationship between current-air flow and current-fuel flow, and generates the first control command to adjust the power of the intake pump and methanol fuel pump. The power management controller compares the real-time temperature with a preset target temperature range and generates a first control command to adjust the speed of the cooling water pump or cooling fan.

4. A direct methanol fuel cell control system for unmanned aerial vehicles according to claim 1, characterized in that, The hybrid power supply unit includes a first ideal diode control circuit and a second ideal diode control circuit; The first ideal diode control circuit is composed of a first ideal diode controller driving a first P-MOSFET. The source of the first P-MOSFET is directly connected to the output terminal of the methanol fuel cell stack, and the drain is connected to the power bus. The second ideal diode control circuit is composed of a second ideal diode controller driving a second P-MOSFET; the source of the second P-MOSFET is connected to the output terminal of the lithium battery pack, and the drain is connected to the power bus. The first ideal diode controller / second ideal diode controller automatically controls the on / off state of the first P-MOSFET / second P-MOSFET by monitoring the source-drain voltage difference of the first P-MOSFET / second P-MOSFET in real time: when the source voltage of the first P-MOSFET / second P-MOSFET is higher than its drain voltage, the first ideal diode controller / second ideal diode controller drives the first P-MOSFET / second P-MOSFET to enter the conduction state, and vice versa. When the first P-MOSFET is in the on state, the direct methanol fuel cell stack supplies power to the power bus; when the second P-MOSFET is in the on state, the lithium battery pack supplies power to the power bus.

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