Everyone should have seen the single-cylinder engine of tractor with a big iron plate on the side. This is the flywheel, which can use the inertia energy of high-speed rotation to stabilize the engine speed and obtain stable power output.
But now someone wants to use this big flywheel on electric cars. Of course, its function is not to stabilize the power output, but to take a fancy to its energy storage characteristics.
There are foreign media reports, University of London City College and Dynamic? Boost? Systems has jointly developed a flywheel energy storage device, namely flywheel battery, which can supply power for electric vehicles.
You can understand it as a kind of electromechanical.
Simply put, it is to realize the mutual conversion and storage between electric energy and flywheel mechanical kinetic energy in a physical way through the motor/generator reciprocating bidirectional motor. And we often say that lithium batteries belong to chemical batteries, which are the mutual transformation of chemical energy and electric energy.
Its structure is not complicated. A typical flywheel energy storage system consists of five main components: flywheel body, bearing, bidirectional motor, power converter and vacuum chamber.
The flywheel body is the core component of the flywheel energy storage system, which aims to improve the ultimate angular velocity of the rotor, reduce the weight of the rotor and maximize the energy storage function of the flywheel energy storage system. It is mostly made of carbon fiber material.
The bidirectional motor operates as a motor when storing energy, and is driven by energy recovered from the outside to accelerate the rotation of the flywheel. At this time, electric energy is converted into kinetic energy. When the energy is released, the motor is converted into a generator, and the flywheel drives the motor to generate electricity and supply power to the driving motor, thus completing the conversion from mechanical energy to electrical energy. In this process, the speed of the flywheel will decrease continuously.
The purpose of power converter is to improve the flexibility and controllability of flywheel energy storage system, and convert the output electric energy into electric energy that meets the power supply requirements of load through frequency modulation, rectification or constant voltage.
The main function of the vacuum chamber is to provide a vacuum environment and reduce the wind resistance loss when the flywheel rotates.
The performance of bearing directly affects the reliability, efficiency and life of flywheel energy storage system. The flywheel energy storage system mostly adopts magnetic suspension system, which reduces the friction when the motor rotor rotates, reduces the mechanical loss and improves the energy storage efficiency.
This sounds novel, but in fact, this technology appeared as early as the early 1980s, when Oerlikon Engineering Company in Switzerland successfully developed a flywheel-driven bus.
You may be curious, how powerful is the flywheel battery?
In 2007, Porsche also studied the flywheel battery. In 2009, this technology was used in Le Mans 9 1 1? GT3？ On the RHybrid racing car, the flywheel energy storage system was installed under the co-pilot seat at that time, and its weight was only 103 lb (about 46.7 kg).
When running at full speed, the speed of the flywheel can be close to 40000 rpm? 16 inch diameter flywheel can provide 0.2 kwh of energy. Although it is small in capacity, it is very powerful. It can provide 163 horsepower (about120 kw) for 6 seconds and charge and discharge frequently and quickly, which won a lot of competition time for 9 1 1 at that time.
Because under normal circumstances, when the racing car accelerates or decelerates sharply during intense driving, there will be a lot of power input or output, and high power will greatly damage the life of the chemical battery. It is said that in a 24-hour race in New bergson, the battery has to be replaced three times.
The flywheel battery can be used for 25 years without replacement and maintenance, and there will be no loss after repeated charging and discharging for 654.38+0000 times. Moreover, it can be said that there is almost no power limit, which is similar to a super capacitor and can be charged and discharged quickly.
In addition, flywheel battery is better than chemical battery in absorbing braking kinetic energy. For example, the deceleration of a general vehicle is only 0.3g, while the flywheel battery can make the deceleration of a racing car reach 1g, thus reducing the wear of brake pads and improving the fuel efficiency by 25%. Generally, 2-3 brake pads need to be replaced in rally, while flywheel battery models only need to be replaced once.
These reduced replacement times can buy a lot of time for the game. Later, the flywheel energy storage system appeared on the Porsche 9 18 concept car, which can provide 2×75kW extra power for the two motors on the front axle.
It can be said that the flywheel battery is very suitable for automobiles in technology, performance and safety, but why hasn't it developed?
Or because of the low cost performance, although the power is high, it is difficult to improve the capacity, so it is not suitable for electric vehicles that run mileage, but only for sports cars, trucks and other vehicles that need high power.
In fact, considering the large energy storage capacity, high energy storage density, fast charging and unlimited charging and discharging times, many foreign scientific research institutions have introduced flywheel energy storage into wind power generation systems, namely: wind turbine+internal combustion engine+flywheel energy storage.
For example, Vista in America? Technology? In engineering, the flywheel is introduced into the wind power generation system to realize the overall peak regulation. The generating power of flywheel group reaches 300kW, and the large-capacity energy storage flywheel stores 277 kW/h..
With the continuous progress of composite materials, magnetic support, integrated engine and multidisciplinary optimization design technology, the energy storage capacity of flywheel may be further improved, and its application in automobile industry is still broad.
This article comes from car home, the author of the car manufacturer, and does not represent car home's position.