Fuel cell buses belong to electric buses, and their key technologies are the same as those of ordinary electric buses, mainly including battery technology, motor technology and controller technology:
1, battery technology
Battery is the power source of fuel cell vehicles, and it is also the key factor that has always restricted the development of fuel cell vehicles. Fuel cell directly converts the chemical energy of fuel into electric energy, which has high energy conversion efficiency, high specific energy and specific power, and can control the reaction process, and the energy conversion process can be carried out continuously. Therefore, it is an ideal automobile battery, and some key technologies have yet to be broken through.
2. Motor technology
The driving motor of electric vehicle is an essential key component of all electric vehicles. There are four kinds of motors widely used: DC brushless motor, permanent magnet brushless motor, AC induction motor and switched reluctance motor. The four kinds of motors have their own advantages and disadvantages, but for electric vehicles, because the electric energy is provided by various batteries, it is expensive and precious, so it is more reasonable to use the most efficient permanent magnet brushless motor, which has been widely used in modern electric vehicles with power less than 100kW.
3. Controller technology
The speed change and commutation of the controller technology are completed by the motor speed regulating device, and its principle is to control the driving torque and rotating direction of the motor by controlling the voltage and current of the motor. Thyristor chopper speed regulation is widely used in fuel cell buses. By changing the terminal voltage of the motor evenly and controlling the motor current, the stepless speed regulation of the motor can be realized.
Second, the fuel cell bus technical requirements
A fuel cell bus is a bus that uses a fuel cell system as a single power supply or a fuel cell system and a rechargeable energy storage system as a hybrid power supply or a main power supply. According to the Technical Specification for Fuel Cell Bus (JT/T 1342-2020), the fuel cell bus mainly has the following technical requirements:
1, general requirements
In the general requirements part, the basic requirements of fuel cell buses are mainly stipulated from the aspects of environmental adaptation and function. The indexes of temperature, humidity, air pressure and altitude in the conventional environment area suitable for fuel cell buses are defined. At the same time, in view of the cold area, it is emphasized that vehicles need to take special protective measures to ensure that the fuel cell power system can operate in a normal state. At the same time, it also emphasizes the requirements of installing vehicle terminal, which clearly meets the requirements of GB/T32960 series standards.
2. Performance requirements
In the part of performance requirements, the performance requirements of fuel cell buses are put forward from four aspects: power, comfort, driving range and EMC. The acceleration performance (0 ~ 50k m/h acceleration time) of fuel cell bus should be ≤ 30s; The climbing performance varies according to different models, and the maximum climbing degree should be ≥ 12% and 15% respectively. At a constant speed of 40km/h, the driving range should be greater than 300km. In addition, it is stipulated that the ratio of the total rated power of the fuel cell system to the total rated power of the driving motor is not less than 50%, and the rated power of the fuel cell system is not less than 30kW；; In terms of comfort, the influence of the noise of the air compressor and the tail exhaust system on the noise in the car when the fuel cell system is running is mainly considered.
3. Safety requirements
In the part of vehicle safety requirements, the high-voltage warning signs of fuel cell buses and the requirements of vehicle functional safety are mainly stipulated. In addition, the installation position, structural protection requirements and protection level of fuel cell system components on the whole vehicle should be no less than IP67；; Fuel cell buses should have technical requirements and alarm measures to prevent hydrogen fuel leakage; The safety of hydrogen filling is clearly defined.
4, fuel cell system requirements
It mainly includes two aspects: the basic requirements of the fuel cell system and the safety requirements for the installation and use of the fuel cell system on the whole vehicle, including the overall size, structural safety, operation requirements, mechanical and physical characteristics, safety requirements, electrical characteristics, fault protection and so on.
5, on-board hydrogen system requirements
The hydrogen storage container, installation structure and location of hydrogen storage device, hydrogen fuel leakage protection and hydrogen pipeline layout of high-pressure hydrogen storage system for fuel cell buses all have relevant requirements.