Speaking of new energy vehicles, everyone is familiar with pure electric vehicles, plug-in hybrid vehicles, etc., today, our protagonist is another form - hydrogen fuel cell vehicles. In recent years, with the continuous development of the hydrogen energy industry at home and abroad, hydrogen fuel cell vehicles have received wide attention as the most important link in the downstream integrated application of the hydrogen energy industry chain.
What is a hydrogen fuel cell vehicle
Hydrogen fuel cell refers to the device where hydrogen generates electrical energy through a chemical reaction with oxygen, and the driving force of a hydrogen fuel cell vehicle comes from the electric motor on the car, just like a pure electric vehicle.
Although there are two words "battery" in the five words of "hydrogen fuel cell", in fact, it is not the same as the small battery we use every day, or the lithium battery on the car. A fuel cell is actually a power generation device that converts the chemical energy in the fuel into electrical energy. Therefore, this "fuel cell" needs to constantly add "fuel" to generate electricity, and this fuel, the most common is hydrogen.
Although any hydrocarbon that can decompose hydrogen, such as natural gas, alcohol, or methane, can decompose hydrogen, the decomposition product contains carbon dioxide, which is not so environmentally friendly, so the fuel cells used in the car are directly used as "fuel", and the final discharge is only water and heat, without any pollution.
How do hydrogen fuel cells work?
The hydrogen in the hydrogen storage tank reacts chemically with the oxygen in the air in the fuel cell and converts the chemical energy into electricity, which pushes the motor to run, and only water or water vapor is generated after the reaction.
The power system composition of hydrogen fuel cell vehicles
The power system of hydrogen fuel cell vehicles is mainly composed of the following parts:
(1) Fuel port: The filling port of hydrogen fuel is directly connected to the hydrogen storage tank.
(2) Battery: helps to brake when decelerating, and converts part of the mechanical energy into electrical energy to store; release the stored electrical energy when accelerating to help accelerate.
(3) High-pressure hydrogen storage tank: The interior is filled with high-pressure hydrogen as the fuel for the car. Its internal pressure is generally 35MPa, and a small number of vehicles can reach 70MPa.
(4) Safety device: When the car collides or hydrogen leaks, cut off the hydrogen supply of the fuel cell.
(5) PEMFC (Proton Exchange Membrane Fuel Cell) Stack: The most core component of hydrogen fuel cell vehicles, which provides power for electric engines and ensures the smooth running of cars.
(6) Engine (electric): the direct power source of the car.
(7) Driving system: connect the cab to control the running state of the vehicle.
The lungs of hydrogen fuel cells - air compressors
Fuel cell systems consist of stacks and BOP (Balance of Plant). The fuel cell BOP provides the necessary external environment for the stable operation of the stack, including the air system, cooling system, humidification system, power output control and other parts.
For fuel cell systems, if the fuel cell system is compared to the human body, the stack can be compared to the "heart" of the fuel cell, then the air compressor can be called the "lung" of the fuel cell. Similarly, the high-performance output of fuel cell systems requires strong "heart-lung function."
Silicon carbide applications in hydrogen fuel cell vehicles
In electric vehicles, the main application of silicon carbide is in electric drive systems, OBC and DCDC, so in the hydrogen fuel cell system, what is the specific application of silicon carbide?
The above-mentioned air compressor, its power configuration is about 20% of the power of the fuel cell system, so improving the efficiency of the air compressor and reducing costs is an important goal of the design.
The air compressor is the core of the air circulation system, and its performance has an important impact on the efficiency and compactness of the fuel cell system, and under the same conditions, an air compressor with a high degree of matching with the fuel cell system can often directly improve the overall performance of the fuel cell.
Centrifugal air compressors for fuel cells have the "three highs" attribute: high speed, high performance and high efficiency. The "three highs" attribute brings great technical challenges to the centrifugal air compressor system and its power electronic drivers. With the emergence and application of wide bandgap semiconductors such as silicon carbide, this problem is better solved, silicon carbide has the characteristics of "high frequency", "high withstand voltage" and "low conductivity", so that the power semiconductor control device obtains higher switching frequency, higher efficiency and smaller volume, which helps the fuel cell high voltage auxiliary system to improve power density and integration.
Many friends feel that hydrogen fuel cells are far away from us, but in fact, they are not so far. After all, new energy will be the dominant in the future, and hydrogen fuel cell vehicles have so many advantages, looking forward to the future, hydrogen as a fuel car must be shining, the future is absolutely bright, and the environment is friendly enough.