GB/T 38954-2020Hydrogen fuel cell power system for unmanned aerial vehicles (English PDF)

3.4 Shut-down time

The length of time from the moment when the fuel cell power system receives the shutdown instruction (the moment when the manual shutdown starts from the shutdown action) to the moment when all components stop working.

3.5 Rated output power

The maximum continuous output power of the fuel cell power system under normal operating conditions as specified by the manufacturer.

3.6 Output voltage range

Under the normal operating conditions specified by the manufacturer, the output voltage range of the fuel cell power system from startup, operation to shut down.

3.7 Continuous running time

Under normal operating conditions specified by the manufacturer, the continuous time that the output voltage of the fuel cell power system does not exceed the output voltage range when operating at the rated output power.

3.8 Fuel storage module

Pressure device used to store hydrogen (such as hydrogen cylinder).

3.9 Fuel supply module

The assembly of all the components, pipe connections and controls which is used to deliver hydrogen to the fuel cell hydrogen inlet, from the hydrogen cylinder to the stack hydrogen inlet.

4.3 Appearance and structure

4.3.1

The appearance of the fuel cell power system shall be clean, free of

mechanical damage, free of cracks, stains and obvious deformation; there is no rust on the interface contacts.

4.3.2

The accessible parts of the fuel cell power system shall not have sharp edges and corners that may cause personal injury.

4.3.3

During the normal operation of the fuel cell power system, its parts and their connectors shall be stable and reliable; there shall be no instability, deformation, fracture or wear.

4.3.4

The communication interface, power interface, user interface, hydrogen inlet and outlet of the fuel cell power system shall be clearly identified.

4.3.5

The positive and negative terminals and polarity of the fuel cell power system shall be clearly identified for easy connection.

4.4 Other general technical requirements

4.4.1

Environmental requirements for the use of fuel cell power systems:

temperature: -5 °C ~ 40 °C; relative humidity: <= 100%; altitude: <= 3000 m.

4.4.2

The fuel cell power system shall be able to provide sufficient power for the normal flight of the unmanned aerial vehicles.

4.4.3

In the case of normal transmission of communication signals, the fuel cell power system itself or the communication system through the unmanned aerial vehicles shall be able to communicate normally with the ground control system.

4.4.4

The main parameters of the fuel cell power system shall be able to be monitored in real time.

4.4.5

In the case that the unmanned aerial vehicles and the ground control system lose communication, the fuel cell power system shall be able to continue to provide power for the unmanned aerial vehicles and execute the predetermined plan.

4.4.6

The hydrogen cylinders in the fuel cell power system shall have detailed filling records during use.

4.4.7

The minimum design burst pressure of the hydrogen cylinder in the fuel cell power system and the design fatigue resistance counts of the hydrogen cylinder shall meet the relevant requirements of the national standards; in the […]

5.7 Startup/shutdown method

The fuel cell power system shall have at least one of the following startup/shutdown methods:

- Manual;

- Remote control;

- Automatic.

5.8 Shutdown time

The shutdown time of the fuel cell power system shall be less than 2 minutes.

5.9 Continuous operation time

The continuous operation time of the fuel cell power system used on the fixed- wing unmanned aerial vehicle shall not be less than 6 h. The continuous operation time of the fuel cell power system used on the multi-rotor unmanned aerial vehicle shall not be less than 3 h. The continuous operation time can also be determined according to the fuel cell power system's purchase agreement.

5.10 Noise

Under the rated power output, the noise of the fuel cell power system shall not exceed 78 dB.

5.11 Vibration resistance

Under normal operating conditions, the fuel cell power system shall be able to resist vibration; keep its mechanical and electrical connections normal; the hydrogen leakage rate shall meet the requirements in 5.19; the fuel concentration in the cabin shall meet the requirements in 5.15.

5.12 Electromagnetic compatibility limits

The electrostatic discharge immunity limit of fuel cell power system shall meet the requirements of test level 3 in GB/T 17626.2-2018. During the test, the […]

5.19 Hydrogen leakage rate

The hydrogen leakage rate shall not exceed 0.5%.

5.20 Alarming function and monitoring function

5.20.1 Alarming function

When the following situations occur, the fuel cell power system shall be able to provide users with warning functions:

- Hydrogen pressure is abnormal (for example, the hydrogen pressure at the outlet of the hydrogen cylinder is lower than the specified minimum pressure; the hydrogen pressure after the pressure reduction valve is lower than the set minimum pressure or higher than the set maximum pressure);

- Output over/under voltage, low fuel cell module output voltage;

- The power output exceeds the overload protection setting value;

- The ambient temperature is too high/low;

- The temperature of the fuel cell module is too high;

- Low voltage of auxiliary energy storage module;

- The fuel concentration in the cabin is too high.

5.20.2 Monitoring function

The fuel cell power system shall have the following monitoring functions:

- Remote measurement: Remotely measure system output voltage, system output current, auxiliary energy storage module's voltage, fuel cell module's output voltage, fuel cell module's output current, hydrogen cylinder's hydrogen pressure, fuel cell module's inlet hydrogen pressure, fuel cell module's temperature, ambient temperature;

- Remote signaling: Remotely provide signals, including fuel cell module over-temperature, low/high hydrogen pressure at the inlet of the fuel cell module, fuel cell system's output over/under pressure, fuel cell system output's overcurrent, low/high hydrogen pressure of hydrogen cylinder, low voltage of auxiliary energy storage module, low/high ambient temperature;

- Remote control: System on/off.

6.3 Test of time to reach rated power

After the fuel cell power system is allowed to stand for 2 hours in the tested ambient temperature, measure the time from the time after the startup of the fuel cell system to the rated power output of the fuel cell power system.

6.4 Test of rated output power

Under the rated output power of the fuel cell power system as indicated by the supplier, the continuous operation of the fuel cell power system is not shorter than the continuous operation time identified by the supplier; the output voltage of the fuel cell power system is recorded every second; its value shall not exceed the output voltage range as indicated by the supplier at any time throughout the test process.

6.5 Test of power overload rate

Make the fuel cell power system run at no less than 150% of the rated output power as stated by the manufacturer. Monitor the continuous operation time of the fuel cell power system in this state. After running for more than 2 minutes, shut down the fuel cell power system according to the shutdown method specified by the manufacturer.

6.6 Test of output voltage range

During the entire test process from 6.2 ~ 6.5, the output voltage of the fuel cell power system is monitored and recorded at an interval of 1 s. In the whole process from startup to shut down, the voltage range of the fuel cell power system from low to high is the output voltage range of the fuel cell power system.

6.7 Electric efficiency test

Start the fuel cell power system; disconnect the auxiliary energy storage module;

run the fuel cell power system for 30 minutes at the rated power W rating . Divide the cumulative net power generation energy during this period by the energy as corresponding to the cumulative hydrogen consumption Q consumption (use a low enthalpy value of 242 kJ/mol). Use the formula (1) to calculate the electric efficiency eta generation of the fuel cell power system (1 kW·h = 3600 kJ).

eta generation = [0.5 x W rated / (242 x Q consumption/3600)]×100% ........................(1) […]

6.17 Fuel concentration test in exhaust gas

The fuel cell power system is operated at the rated output power. A hydrogen concentration tester is installed at 10 cm of the extension line of the central axis of the gas exhaust port, to measure the concentration of hydrogen in the exhaust gas during an operating time of not less than 10 minutes; record a value every second.

6.18 Cabin protection level test

According to 13.4 and 14.2.3 of GB/T 4208-2017, respectively carry out dustproof and waterproof tests. For the fuel cell power system or part of its components installed in the cabin or the unmanned aerial vehicle's housing, when the test is performed, it needs installing the fuel cell power system or some of its components in the cabin or unmanned aerial vehicle's housing.

6.19 Service life test

According to the actual use of the unmanned aerial vehicle, the operating conditions of the fuel cell power system during the continuous operation time indicated by the manufacturer are determined according to the purchase agreement; this is used as a cycle, to repeatedly operate the fuel cell power system. When the output voltage of the fuel cell power system exceeds the voltage output range as indicated by the manufacturer in a certain cycle, record the cumulative operation time and the number of startups and shutdowns of the fuel cell power system.

The time during which the fuel cell power system is shut down and stopped during the cycle cannot be calculated as the cumulative operating time.

Refer to Appendix B for typical life test methods.

6.20 Hydrogen leakage rate test

Install a flow meter on the gas pipeline before the hydrogen inlet of the fuel cell module. Set the inlet pressure of the hydrogen entering the fuel cell module at its working pressure (that is, the hydrogen outlet pressure of the fuel storage and supply module that supplies hydrogen to the fuel cell module). Ventilate for

1 minute when the hydrogen outlet of the fuel cell module is open. Then turn off the fuel cell module's hydrogen outlet. Keep the pressure for 10 minutes.

Record the value of the flowmeter, which is the leakage (convert its unit to mol/s). If helium or nitrogen is used as the test gas, the amount of leakage shall […]