The flywheel energy storage battery system consists of three core parts: a flywheel, an electric motor generator, and a power electronic conversion device.

The power electronic conversion device inputs electrical energy from the outside to drive the motor to rotate. The motor drives the flywheel to rotate, and the flywheel stores kinetic energy (mechanical energy). When external loads require energy, the flywheel drives the generator to rotate, converting kinetic energy into

Electric energy is then transformed into various frequencies and voltage levels of electrical energy required by the load through power electronic conversion devices to meet different needs. Due to the fact that the input and output are independent of each other, the design often uses a single motor to implement the motor and generator, and the input output converter is also merged into one, which can greatly reduce the size and weight of the system. At the same time, due to the fact that in practical work, the speed of the flywheel can reach 40000~50000 r/min, and generally metal made flywheels cannot withstand such high speeds, the flywheel is generally made of carbon fiber, which is both light and strong, further reducing the weight of the entire system. At the same time, in order to reduce energy loss (mainly friction loss) during the charging and discharging process, both the motor and flywheel use magnetic bearings to suspend them and reduce mechanical friction; Simultaneously place the flywheel and motor in a vacuum container to reduce air friction. The net efficiency (input output) of the flywheel battery is about 95%.

In actual use, the flywheel device mainly includes the following components: flywheel, shaft, bearings, motor, vacuum container, and power electronic converter. The flywheel is the core component of the entire battery device, which directly determines the amount of energy stored in the entire device. The energy stored is determined by the formula E=j ω^ 2 Decisions. In the formula, j is the rotational inertia of the flywheel, which is related to the shape and weight of the flywheel; ω Is the rotational angular velocity of the flywheel.

Comparison between Flywheel Battery and Other Batteries

The most widely used energy storage battery is undoubtedly a chemical battery, which converts electrical energy into chemical energy for storage and then converts it into electrical energy output. It is inexpensive and technologically mature, but it has serious pollution, low efficiency, long charging time, short power consumption time, and is difficult to control electrical energy during use.

Another energy storage battery is a superconducting battery, which converts electrical energy into magnetic energy and stores it in the magnetic field of the superconducting coil. Due to the lack of resistance in the superconducting state of the coil, the energy loss is very small, the efficiency is also high, and the environmental pollution is also small. However, due to the fact that the superconducting state can only be achieved when the coil is in an extremely low temperature, the low temperature required to maintain the superconducting state of the coil requires a lot of energy, and the maintenance device is too large to be easily miniaturized, so the prospects for the household market are not strong.

Flywheel batteries, on the other hand, take into account the advantages of both. Although their prices are relatively high in recent years, with the advancement of technology, they will have a very broad prospect. Below is a specific comparison of the advantages and disadvantages of the three through Table -1.