阅读说明：本技术 一种无人直升机用应急电源系统 (Emergency power supply system for unmanned helicopter ) 是由 汤宪宇 于 2020-05-19 设计创作，主要内容包括：本发明公开了一种无人直升机用应急电源系统,涉及无人直升机领域。提出了一种将集成式式无人直升机用应急电源系统。该系统包含锂电池组、电池管理系统模块和电池充电模块三个部分：锂电池组为整个系统的能量储存中枢,当无人直升机主电源故障时,输出能量；电池管理系统模块负责检测电池的单体电压、总电压、充放电电流、温度等电池工作状态,并经过数据处理后对电池的SOC/SOH参数进行估计,并控制电池充电、均衡等动作；电池充电模块将无人直升机母线输入的直流电压源转换为稳定的恒流限压源为电池进行充电。(The invention discloses an emergency power supply system for an unmanned helicopter, and relates to the field of unmanned helicopters. An emergency power supply system for an integrated unmanned helicopter is provided. The system comprises a lithium battery pack, a battery management system module and a battery charging module: the lithium battery pack is an energy storage center of the whole system, and when a main power supply of the unmanned helicopter fails, energy is output; the battery management system module is responsible for detecting the working states of the battery, such as the monomer voltage, the total voltage, the charging and discharging current, the temperature and the like of the battery, estimating the SOC/SOH parameters of the battery after data processing, and controlling the actions of charging, balancing and the like of the battery; the battery charging module converts a direct-current voltage source input by the unmanned helicopter bus into a stable constant-current voltage-limiting source to charge the battery.)

1. An emergency power supply system for an unmanned helicopter, comprising: the system comprises a lithium battery pack, a battery management system module and a battery charging module, wherein the lithium battery pack is an energy storage center of the whole system and outputs energy when a main power supply of the unmanned helicopter fails; the battery management system module is responsible for detecting the working states of the battery, such as the monomer voltage, the total voltage, the charging and discharging current, the temperature and the like of the battery, estimating the SOC/SOH parameters of the battery after data processing, and controlling the actions of charging, balancing and the like of the battery; the battery charging module converts a direct-current voltage source input by the unmanned helicopter bus into a stable constant-current voltage-limiting source to charge the battery.

2. The system of claim 1, wherein the lithium battery pack comprises: the system comprises a lithium battery, a fuse, a Hall sensor, a temperature sensor and a detection line, wherein the lithium battery is used as an energy storage center of an emergency power supply system and is used for supplying power to the whole system when a main power supply of the unmanned helicopter is abnormal; the fuse is used as the last fuse to prevent danger when the battery fails; the Hall sensor is used for detecting the charging and discharging current of the battery; the temperature sensor is used for detecting the temperature of the battery during working and preventing the battery from faults such as overheating or overcooling; the detection line is connected with the battery management system, monitors the voltage of the battery monomer and balances the battery monomer when the battery monomer is unbalanced.

3. The system of claim 1, wherein the battery management system module comprises: the system comprises an information acquisition unit, a battery equalization unit, a power supply unit, a communication fault alarm unit, a CPU unit and a charging energy-saving unit, wherein the information acquisition unit detects battery operation parameters such as single battery voltage, total battery voltage, temperature, charging and discharging current and the like by adopting a battery detection chip; the battery balancing unit adopts a passive balancing mode to ensure that the voltage between the battery monomers is within a threshold range; the power supply unit adopts an isolated power supply to supply power to the whole battery management system module; the communication fault alarm unit is responsible for communicating with an upper computer in real time and giving an alarm when the battery fails; the CPU is a central hub of the whole battery management system module and is responsible for processing the detection information, then sending an action command and communicating with an upper computer; the charging enabling control circuit controls the battery charging module, and when the battery meets the charging condition, the charging enabling control circuit controls the battery charging module to charge the battery.

4. The system of claim 1, wherein the battery charging module comprises: the system comprises an input filtering unit, a DC/DC power supply unit, an enabling unit, an output filtering unit, a hardware power protection unit and a hardware protection control unit, wherein the input filtering unit has a bidirectional isolation function and performs electromagnetic filtering on an unmanned helicopter bus and a battery charging module; the DC/DC power supply unit converts the direct-current voltage source of the bus of the unmanned helicopter into a constant-current voltage-limiting power supply to charge a lithium battery of an emergency power supply of the unmanned helicopter;

the enabling unit is controlled by the battery management system module and enables the DC/DC power supply module when the charging condition is met;

the output filter unit adopts an ᴨ type filter circuit to filter alternating current components in the output voltage of the DC/DC power supply unit;

the hardware protection power unit adopts an MOS tube and a diode to form an output switch circuit, and disconnects a charging loop when charging is not performed;

the hardware protection control unit comprises a hardware voltage protection circuit and an output control circuit, and controls the hardware protection power unit to disconnect the charging loop when the battery does not meet the charging condition or the output voltage of the DC/DC power supply module is higher than the hardware voltage protection hardware voltage.

5. According to the system of claim 1, the lithium battery pack, the battery management system module and the battery charging module are integrated into a whole, and the integrated emergency power supply system for the unmanned helicopter is small in size, light in weight and good in stability.

6. According to the system of claim 4, in order to ensure the safety of on-board charging, the system adopts three-level charging protection;

the first stage is a charging enabling circuit, and the power supply module can start power supply conversion only under the condition that the battery management system is enabled;

the second stage is an output control circuit, and the output control circuit can be enabled only under the condition that the output voltage meets the requirement, so that the charging circuit is conducted;

the third stage is a hardware voltage protection circuit, when the output voltage of the power supply module is higher than the protection voltage, the hardware voltage protection circuit can forcibly close the PMOS tube, so that the charging loop is closed; the three-level charging protection can ensure that the battery charging system cannot fail when any one-level protection fails, thereby greatly reducing the probability of overcharging of the battery in terms of probability and protecting the safety of the battery.

7. The system of claim 4, aiming at the characteristic that the unmanned helicopter is very sensitive to weight, the power module with high conversion efficiency, the MOS tube with low conduction impedance and the diode with low conduction voltage drop are adopted, and the heat productivity of the charging module is reduced as much as possible, so that the heat dissipation area is reduced, and the weight of the charging module is further reduced.

Technical Field

The invention relates to the technical field of unmanned helicopters, in particular to an emergency power supply system for an unmanned helicopter.

Technical Field

The unmanned helicopter has flight characteristics of vertical take-off and landing, hovering and the like, and plays an important role in agriculture, electric power, traffic and the like. Especially, along with the development of power energy storage systems, sensors and flight control technologies in recent years, the unmanned helicopter is rapidly developed. When the main power supply system can not output electric energy normally in the flying process of the unmanned helicopter, an airborne emergency power supply is required to supply power for key electric equipment such as a flight control system, measurement and control equipment and the like so as to ensure the flight safety and return to the home as soon as possible. The lithium ion battery has the advantages of high energy density, no memory effect and the like, and is widely applied to the emergency power supply system of the unmanned helicopter.

Patent CN203491696U discloses that under normal conditions of the unmanned helicopter, the main power voltage of the unmanned helicopter is 28.5V and 12V, and the emergency power supply comprises at least one 24V battery pack or 12V battery pack. When the main power supply fails, the emergency power supply ensures that the direct-current basic load influencing flight safety normally works, so that 30min emergency flight time is ensured.

The existing unmanned helicopter emergency power supply system mostly adopts the design that a battery management system is integrated in a battery pack and a battery charging system is independent and is independently used as a module. This results in separate housings for both the battery pack of the battery management system and the battery charging system, which adds weight to the emergency power system. In addition, the battery management system and the battery charging system are provided with various connecting wires such as a charging control signal wire, a charging power wire and the like, so that the problems of wrong insertion and damage of a connector assembly and the like are easily caused during maintenance, and the fault rate of the system is increased.

Disclosure of Invention

Based on the problems, the invention provides an integrated emergency power supply system for the unmanned helicopter, which integrates a battery charging module, a battery management system module and a lithium battery pack into a whole and has the advantages of small volume, light weight and good stability.

The system comprises a lithium battery pack, a battery management system module and a battery charging module:

the lithium cell group is entire system's energy storage maincenter, and it contains lithium cell, fuse, hall sensor, temperature sensor and detection line: the battery pack is formed by connecting 6 high-rate ternary lithium ion batteries in series, the voltage of the battery pack is 25.2V when the battery pack is fully charged, and the battery capacity can ensure that the unmanned helicopter can fly for at least 30min when the battery pack is fully charged; the fuse is connected in series with the positive output end of the lithium battery pack, and when the battery charging and discharging circuit breaks down, the fuse can be used as the last fuse to prevent danger. The Hall sensor is formed by double-range output Hall, can separately detect the charging current and the discharging current, and ensures the detection precision of the battery current. The temperature sensor adopts an NTC temperature sensor, and the real-time temperature value in the charging and discharging process of the battery is monitored according to the change of the NTC resistance value. The detection lines lead out the single voltage of the detection battery at the positive end and the negative end of each battery, and balance the batteries through the detection lines when the batteries are unbalanced.

The battery management system module is responsible for detecting the working states of the battery such as the monomer voltage, the total voltage, the charging and discharging current, the temperature and the like of the battery, estimating the SOC/SOH parameters of the battery after data processing, controlling the actions of battery charging, balancing and the like according to the working state of the battery, and comprises an information acquisition unit, a battery balancing unit, a power supply unit, a communication fault alarm unit, a CPU unit and a charging enabling control circuit: the information acquisition unit adopts LTC6811 as a core detection device, and detects the voltage of a single body of the lithium battery pack by using a voltage detection port of the LTC 6811; signals such as total voltage, temperature, current and the like of the battery are amplified by a resistance voltage division and an operational amplifier, then input to a general voltage detection port GPIOx of a battery voltage detection chip, and are transmitted to a CPU unit together with the voltage of a battery monomer after being collected by an internal AD; the battery balancing unit adopts a passive balancing mode to ensure the voltage balance among the batteries, is integrated with the information acquisition unit and comprises an S pin, a discharge resistor and a discharge switch which are controlled by a battery detection chip; the power supply unit supplies power to the whole battery management system module and comprises an input filter circuit, an isolation power supply module and an output filter circuit; the communication fault alarm unit comprises a communication chip circuit and a fault alarm circuit, the communication chip circuit is responsible for communicating with the unmanned helicopter upper computer, and the fault alarm circuit is sent to the unmanned helicopter upper computer in a high-low level mode; the CPU unit is a control core of the whole battery management system module, all information is gathered to the CPU unit for calculation and then is sent to the corresponding execution unit, the CPU unit comprises a CPU chip, a watchdog circuit, a crystal oscillator circuit and a download circuit, and is responsible for receiving data acquired by the information acquisition unit and processing the data, estimating the residual capacity (SOC) of the battery, sending an enable signal to the charging control unit when the battery meets the charging condition, sending a balance signal to the battery balance unit when the battery meets the balance condition, and sending a fault signal to the communication fault alarm circuit when the battery generates fault alarm information such as overshoot, overcurrent and overtemperature; the charging enabling control circuit controls whether the charging module charges the battery or not, and comprises a charging enabling circuit and an output enabling circuit.

The battery charging module converts a direct-current voltage source input by the unmanned helicopter bus into a stable constant-current limiting voltage source to charge the battery, and comprises an input filtering unit, a DC/DC power source unit, an enabling unit, an output filtering unit, a hardware protection power unit and a hardware protection control unit: the input filter circuit has a bidirectional isolation function, interference signals on the unmanned helicopter bus can be inhibited, and meanwhile harmonic waves and electromagnetic interference signals generated when the switching power supply works are prevented from influencing the unmanned helicopter bus. The DC/DC power supply module circuit adopts a high-efficiency power supply module to convert a direct-current voltage source of the unmanned helicopter bus into a constant-current voltage-limiting power supply to charge the lithium battery of the unmanned helicopter emergency power supply. The output filter circuit adopts an ᴨ type LC filter circuit, and effectively filters alternating current components in the power supply module output power supply by utilizing high impedance of an inductor to alternating current signals and low impedance of a capacitor to the alternating current signals. The hardware protection power circuit consists of a low-conduction voltage drop diode, a low-conduction impedance MOS tube and a driving circuit thereof, wherein the diode prevents a battery charging system from being reversely charged, the MOS tube and the driving circuit thereof form a control switch of a charging loop, and the charging loop is disconnected when the charging condition is not met. The charging enabling circuit is isolated from the battery management system in an optical coupling isolation mode, and when the charging condition is met, the battery management system controls the optical coupling to conduct the enabling charging module. The hardware protection control circuit comprises a hardware voltage protection circuit and an output control circuit, and output signals of the two parts are combined by a NAND gate to control the hardware protection power circuit: the output control circuit is similar to the charging enabling circuit, and enables the output control circuit when the battery charging condition is met; the hardware voltage protection circuit adopts a voltage division circuit to compare with reference voltage in real time, outputs low level when the output voltage is higher than hardware protection, closes a hardware protection power circuit, and disconnects a charging loop to protect the safety of the battery.

Compared with the prior art, the invention has the advantages that:

(1) the invention provides an integrated unmanned helicopter emergency power supply system which integrates a battery charging module, a battery management system module and a lithium battery pack into a whole and has small volume, light weight and good stability, aiming at the problems of discrete type, heavy weight and complex maintenance of the existing unmanned helicopter emergency power supply system.

(2) Aiming at the characteristic that the unmanned helicopter is very sensitive to the weight of a charging system, the invention adopts a power module with the conversion efficiency as high as 96%, an MOS tube with low conduction impedance and a diode with low conduction voltage drop, and reduces the heat productivity of the charging module as much as possible, thereby reducing the heat dissipation area and further reducing the weight of the charging module.

(3) In order to ensure the safety of charging on the machine, the charging system adopts three-level charging protection. The first stage is a charging enabling circuit, and the power supply module can start power supply conversion only under the condition that the battery management system is enabled; the second stage is an output control circuit, and the output control circuit can be enabled only under the condition that the output voltage meets the requirement, so that the charging circuit is conducted; the third level is a hardware voltage protection circuit, and when the output voltage of the power supply module is higher than the protection voltage, the hardware voltage protection circuit can forcibly close the PMOS tube, so that the charging loop is closed. The three-level charging protection can ensure that the battery charging system cannot fail when any one-level protection fails, thereby greatly reducing the probability of overcharging of the battery in terms of probability and protecting the safety of the battery.

Drawings

FIG. 1 is a general block diagram of an embodiment of the present invention;

FIG. 2 is a schematic diagram of an exemplary lithium battery pack of the present invention;

FIG. 3 is a block diagram of an exemplary battery management system of the present invention;

FIG. 4 is a schematic diagram of a charging module according to an embodiment of the present invention;

FIG. 5 is a flowchart of an example operation of the present invention.

Detailed Description

In order to make the objects, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are some, but not all, embodiments of the present invention. All embodiments obtained by those skilled in the art based on the embodiments of the present invention without any creative efforts shall fall within the protection scope of the present invention.

As shown in fig. 1, the emergency power supply system for the unmanned helicopter includes three departments, i.e., a lithium battery pack, a battery management system module, and a battery charging module. The lithium battery pack is an energy core of the emergency power supply system, 6 sections of ternary lithium ion batteries are connected in series, and when the main power supply system cannot normally output electric energy, a rated 24V emergency power supply is provided to the outside. The battery management system module is responsible for detecting real-time working states of voltage, current, temperature and the like of the lithium battery pack, estimating the residual capacity of the battery, and controlling actions of charging, balancing and the like of the lithium battery pack according to state parameters of the lithium battery pack. The battery charging module is responsible for converting a constant voltage source of the unmanned helicopter bus into a constant current limiting voltage source to charge the lithium battery pack and comprises an input filtering unit, a DC/DC power supply module unit, an output filtering unit, a hardware protection power unit, a charging enabling unit and a hardware protection control unit.

As shown in fig. 2, the lithium battery pack is an energy core of the whole emergency power supply system, and when the main power supply system cannot output electric energy normally, a rated 24V emergency power supply is provided to the outside, so that the normal operation of a direct current basic load influencing the safety of the unmanned helicopter is ensured, and the emergency flight time of the unmanned helicopter is ensured. The lithium battery pack consists of a ternary lithium ion battery, a fuse, a Hall sensor, a temperature sensor and a detection line. The lithium ion battery is formed by connecting 6 sections of high-rate ternary lithium ion batteries in series, the voltage of the battery pack is 25.2V when the battery pack is fully charged, and the battery capacity can ensure that the unmanned helicopter can fly for at least 30min when the battery pack is fully charged. The fuse is connected in series with the positive output end of the lithium battery pack, and when the battery charging and discharging circuit breaks down, the fuse can be used as the last fuse to prevent danger. The Hall sensor is formed by double-range output Hall, can separately detect the charging current and the discharging current, and ensures the detection precision of the battery current. The temperature sensor adopts an NTC temperature sensor, and the real-time temperature value in the charging and discharging process of the battery is monitored according to the change of the NTC resistance value. The detection lines lead out the single voltage of the detection battery at the positive end and the negative end of each battery, and balance the batteries through the detection lines when the batteries are unbalanced.

As shown in fig. 3, the battery management system module is a control center of the emergency power system, and is responsible for detecting real-time working states of the lithium battery pack, such as voltage, current, and temperature, estimating the remaining capacity of the battery, and controlling actions of charging and balancing the lithium battery pack according to state parameters of the lithium battery pack. The battery management system module comprises an information acquisition unit, a battery equalization unit, a power supply unit, a communication fault alarm unit, a CPU unit and a charging enabling control circuit.

The information acquisition unit adopts LTC6811 as a core detection device, the voltage range of a battery measured by the information acquisition unit is 0-5V, and the measurement error is less than 1.2mV, so that the information acquisition unit is a mature battery detection chip in the current market: detecting the voltage of a single body of the lithium battery pack by using a voltage detection port of the lithium battery pack; the total voltage of the battery is input to a general voltage detection port GPIOx of a battery voltage detection chip after being divided by a resistor and amplified by an operational amplifier, and is sent to a CPU unit together with the voltage of a battery monomer after being collected by an internal AD; similarly, the information of the temperature, the current and the like of the battery is sent to the CPU unit after voltage division, amplification and data acquisition.

The battery equalization unit adopts a passive equalization mode to ensure the voltage equalization among the batteries, is integrated with the information acquisition unit and comprises a battery detection chip, a discharge resistor and a discharge switch, when the pressure difference among the battery monomers is large, the battery detection chip controls the corresponding discharge switch to be closed, the high-voltage battery starts to discharge, and the discharge equalization is stopped until the pressure difference among the battery monomers meets the requirements.

The power supply unit supplies power to the whole battery management system module, is responsible for converting a fluctuating voltage source on a bus of the unmanned helicopter into a stable direct-current voltage source to supply the internal units of the module to normally work, and comprises an input filter circuit, an isolation power module and an output filter circuit.

The communication fault alarm unit comprises a communication chip circuit and a fault alarm circuit, wherein the communication chip circuit is responsible for communicating with an upper computer of the unmanned helicopter and sending the residual capacity of the battery, fault alarm information and the like to the unmanned helicopter; and the fault alarm circuit sends fault information such as overcharge, over-temperature and overcurrent to the upper computer of the unmanned helicopter in a high-low level mode when the battery generates the fault information.

The CPU is the control core of the whole battery management system module, and all information is gathered to the CPU for calculation and then sent to the corresponding execution unit. The CPU unit comprises a CPU chip, a watchdog circuit, a crystal oscillator circuit and a download circuit, is responsible for receiving data acquired by the information acquisition unit and processing the data, estimates the residual capacity (SOC) of the battery, sends an enabling signal to the charging control unit when the battery meets the charging condition, sends a balancing signal to the battery balancing unit when the battery meets the balancing condition, and sends a fault signal to the communication fault alarm circuit when the battery generates fault alarm information such as overshoot, overcurrent and overtemperature.

The charging enabling control circuit controls whether the charging module charges the battery or not, and comprises a charging enabling circuit and an output enabling circuit. When the charging condition is met, the CPU unit sends a charging enabling signal to the battery charging module through the charging enabling circuit, so that the charging module starts to carry out power supply conversion, and after the output voltage of the charging module is stabilized, the CPU unit closes a charging loop through the output enabling circuit to start charging the battery. When the battery is fully charged or a fault alarm occurs, the CPU unit controls the output enabling circuit to disconnect the charging loop, and then controls the charging enabling circuit to be invalid, so that the charging module stops working.

The battery charging module shown in fig. 4 converts a direct-current voltage source input by the unmanned helicopter bus into a stable constant-current voltage-limiting source to charge the battery. The battery charging module comprises an input filtering unit, a DC/DC power supply unit, an enabling unit, an output filtering unit, a hardware protection power unit and a hardware protection control unit.

The input filtering unit has a bidirectional isolation function, can inhibit interference signals on the bus of the unmanned helicopter, and simultaneously prevents harmonic waves and electromagnetic interference signals generated when the power supply module works from influencing the bus of the unmanned helicopter. The input filter circuit comprises a TVS diode, a filter capacitor CAP1, a common mode inductor CM1 and a filter capacitor CAP 2.

The DC/DC power supply unit converts a direct-current voltage source input by the unmanned helicopter bus into a stable constant-current voltage-limiting power supply, so that the lithium battery of the unmanned helicopter emergency power supply is charged. The DC/DC power supply module adopts a non-isolated BUCK-BOOST power supply module of Synqor company, and can convert a constant voltage power supply into a constant current voltage limiting power supply. The power module adopts a synchronous rectification technology, can effectively improve the conversion efficiency of the power module, has the highest conversion efficiency of 96 percent, can effectively reduce the heat productivity of the charging module, reduces the area of the radiating fins and further lightens the weight of a charging system.

The output filtering unit can effectively filter alternating current components in the power supply module output power supply, and prevent the alternating current signals from generating adverse effects such as electromagnetic interference on loads. The output filter circuit adopts an ᴨ type LC filter circuit which is composed of CAP3, L1 and CAP 4.

The hardware protection power unit comprises an anti-reverse charging DIODE DIODE and a charging switch consisting of a PMOS tube and a driving circuit thereof. The reverse charging prevention DIODE selects a low-on-resistance power DIODE, and can control the flowing direction of current to prevent the reverse charging of the battery from damaging devices in the circuit. PMOS, R1, R2 and OC2 constitute the switch of the charging circuit, and when the optical coupler OC2 is normally conducted, the output voltage V is_bus+After voltage division is carried out by the resistors R1 and R2, voltage difference is formed between GS of the PMOS, the PMOS is conducted, and a charging loop is conducted; when the optical coupler OC2 is closed, the PMOS is closed, and the charging loop is disconnected. In order to reduce the heat productivity of the charging system, the PMOS tube selects a power MOS tube with low on-resistance.

The charging enabling unit controls whether the DC/DC power supply unit works, when an external control circuit is effective (voltage difference exists between EN + and EN < - >), the optical coupler OC1 works, an Enable pin of the DC/DC power supply module is pulled down, and the DC/DC power supply module works. When the battery is fully charged or does not meet the charging requirement, the external control circuit is invalid, the optical coupler OC1 is cut off, the Enable pin of the DC/DC power supply module is suspended, and the power supply module stops working.

The hardware protection control unit comprises a hardware voltage protection circuit and an output control circuit, and output signals of the two parts control the on and off of the hardware protection power circuit after passing through the NAND gate. The hardware voltage protection circuit comprises a voltage division circuit and a comparison circuit, and V is used for controlling the voltage of the output voltage to be lower than the hardware protection voltage_bus+The voltage obtained by dividing the voltage by the resistors R7 and R8 is lower than the voltage V_refAfter comparison by the comparator COMP, a high level is output as an input signal of the NAND gate NAND, and when the output control circuit is effective, the NAND gate NAND outputs a low level, and the optocoupler OC2 is turned on, thereby controlling the output PMOS to be turned on. Otherwise when V_bus+Above a given voltage, the optocoupler OC2 is turned off, thereby controlling the output PMOS to turn off. The output control circuit electrically isolates the controlled weak current signal from the charging part by the optocoupler, when the output control circuit is effective (namely, a pressure difference exists between OutCtrl + and OutCtrl-), the optocoupler OC3 is conducted to output a high level to the NAND gate NAND, and when the hardware voltage protection circuit outputs a high level, the NAND gate outputs a low level to enable the optocoupler OC2 to be conducted so as to control the conduction of the PMOS in the hardware protection power circuit. And otherwise, when the output control circuit is invalid (namely no pressure difference exists between the OutCtrl + and the OutCtrl-), the PMOS is turned off, and the output loop is disconnected. It can be seen that the hardware voltage protection power circuit can be turned on only when the hardware voltage protection circuit and the output control circuit output high levels at the same time, and the charging loop is turned off when any one signal is at a low level.

A flow chart of the operation of an emergency power supply for an unmanned helicopter is shown in fig. 5. In actual work, the lithium battery pack is the main center of the whole system, and the battery charging module and the battery management system module are used for ensuring safe and reliable working service of the lithium battery pack. The battery management system module is a control core of the whole emergency power supply system and is responsible for collecting the working state information of the lithium battery pack and controlling actions such as charging, balancing and the like according to the battery information. And the battery charging module charges the on-board battery when the battery management system module sends charging information. The working process is that after the unmanned helicopter engine starts a bus to supply power; the battery management system module starts to be electrified; the information acquisition unit acquires information such as monomer voltage, total voltage, charging and discharging current, temperature and the like of the battery; calculating the SOC value of the battery according to the working state information of the battery; the communication and fault alarm unit sends the battery state information to an upper computer of the unmanned helicopter; when the battery needs to be balanced, the balancing circuit is controlled to perform passive balanced discharge; controlling the charge enable circuit to be effective when the battery needs to be charged; the power supply module starts to work to carry out power supply conversion; delaying for 3S for waiting for the output voltage of the power supply module to be stable; controlling an output enabling circuit to be effective and closing a charging loop; starting to perform constant-current voltage-limiting charging on the battery; if the hardware voltage protection occurs in the charging process, the charging loop is directly cut off to stop charging; when the battery is full or a fault alarm occurs, controlling the output enabling circuit to be invalid and cutting off the charging loop; and controlling the charging enabling circuit to be invalid, and stopping the charging module.

Compared with the prior art, the invention has the advantages that:

(1) the invention provides an integrated unmanned helicopter emergency power supply system which integrates a battery charging module, a battery management system module and a lithium battery pack into a whole and has small volume, light weight and good stability, aiming at the problems of discrete type, heavy weight and complex maintenance of the existing unmanned helicopter emergency power supply system.

(2) Aiming at the characteristic that the unmanned helicopter is very sensitive to the weight of a charging system, the invention adopts a power module with the conversion efficiency as high as 96%, an MOS tube with low conduction impedance and a diode with low conduction voltage drop, and reduces the heat productivity of the charging module as much as possible, thereby reducing the heat dissipation area and further reducing the weight of the charging module.

(3) In order to ensure the safety of charging on the machine, the charging system adopts three-level charging protection. The first stage is a charging enabling circuit, and the power supply module can start power supply conversion only under the condition that the battery management system is enabled; the second stage is an output control circuit, and the output control circuit can be enabled only under the condition that the output voltage meets the requirement, so that the charging circuit is conducted; the third level is a hardware voltage protection circuit, and when the output voltage of the power supply module is higher than the protection voltage, the hardware voltage protection circuit can forcibly close the PMOS tube, so that the charging loop is closed. The three-level charging protection can ensure that the battery charging system cannot fail when any one-level protection fails, thereby greatly reducing the probability of overcharging of the battery in terms of probability and protecting the safety of the battery.

In order to make the objects, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are some, but not all, embodiments of the present invention. All embodiments obtained by those skilled in the art based on the embodiments of the present invention without any creative efforts shall fall within the protection scope of the present invention.