Can Permanent Magnet Motors be Used As Generators

The biggest difference between permanent magnet generator and excitation generator is that its excitation magnetic field is generated by the permanent magnet. A permanent magnet is not only a magnetic source, but also a component of the magnetic circuit in the motor.

The magnetic properties of permanent magnets are related to the manufacturing process, the shape and size of permanent magnets, the capacity of magnetizers and the method of magnetization. The specific performance data are very discrete. Moreover, the magnetic flux and magnetic potential provided by permanent magnets in motors also vary with the material properties, dimensions of the remaining parts of the magnetic circuit and the running state of the motor.

Permanent magnet generator has a variety of magnetic circuit structures. The leakage circuit is very complex and the proportion of leakage flux is large. The ferromagnetic material part is easy to be saturated, and the permeance is non-linear. All these increase the complexity of electromagnetic calculation of permanent magnet generator and make the accuracy of calculation lower than that of electric excitation generator.

permanent magnet generator

Like the alternator, the mechanical energy of the prime mover is converted into electric energy output by using the electromagnetic induction principle of the electric potential induced by the magnetic force line cut by the wire. It consists of stator and rotor. The stator is the armature that generates electricity, and the rotor is the magnetic pole. The stator is composed of armature core, uniformly discharged three-phase windings, frame, and end cover.

The magnet rotor is usually hidden pole type, consisting of excitation winding, iron core, and shaft, retaining ring, central ring, etc. The excitation winding of the rotor passes through the DC current and produces a nearly sinusoidal magnetic field (called the rotor magnetic field). Its effective excitation flux interacts with the stationary armature winding. When the rotor rotates, the magnetic field of the rotor rotates along with the same start and every turn. The magnetic wire cuts each phase winding of the stator sequentially, and induces a three-phase alternating current potential in the three-phase stator winding.

When the generator operates with symmetrical load, the three-phase armature current synthesizes to produce a rotating magnetic field with synchronous speed. The interaction between the stator magnetic field and rotor magnetic field will produce braking torque. From the steam turbine/gas turbine, the mechanical torque input overcomes the braking torque coupling and works.

magnet rotor

Advantages of Permanent Magnet Generator

I: It has a simple structure and high reliability. Permanent magnet generator eliminates excitation winding, carbon brush and sliding ring structure of excitation generator. The structure of the whole machine is simple. It avoids burning and breaking of excitation winding, carbon brush and sliding ring structure. The structure of the whole machine is simple. It avoids burning and breaking of excitation winding, wearing and tearing of carbon brush and sliding ring of excitation generator. The reliability is greatly improved.

II: Small size, lightweight, and high specific power. The use of permanent magnet rotor structure makes the internal structure design of the generator arranged very compactly, and the volume and weight of the generator are greatly reduced. The simplification of the permanent magnet rotor structure also reduces the inertia of the rotor, increases the practical speed, and achieves a very high specific power.

III: Medium and low-speed power generation performance is good. Under the same power level, the output power of the permanent magnet generator is twice as high as that of the excitation generator at idle speed. That is to say, the actual equivalent power level of the permanent magnet generator is the excitation generator.

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Applications of High Performance NdFeB Permanent Magnet Materials

In the rare earth functional materials industry, high-performance neodymium permanent magnets are mainly used. Neodymium magnets are mainly used in high-end applications such as new energy and energy-saving and environmental protection, such as EPS, new energy vehicles and so on.
With the technological innovation of the automobile industry and the demand of energy saving and environmental protection, electric or hybrid vehicles with low energy consumption, low noise and low exhaust gas have become the goal of everyone. Bonded Nd-Fe-B magnets have the advantages of high magnetic properties, small size, and high efficiency. The motor using Nd-Fe-B magnets has 8-50% higher efficiency, 10% lower power consumption and 30% lower volume and weight. The development of the automobile is miniaturization, lightweight, high performance, and energy saving and environmental protection.

neo magnets
In addition, bonded neodymium magnets are mainly used in micro-motors and sensors of medium and high-grade vehicles. Each medium and high-grade and luxury car uses 50-80 micro-motors, some even up to 100, with an average of at least 60. For example, the seat motor, window motor, wiper motor, EPS power steering sensor, magnet rotor, onboard CD or hard disk and so on, with the development of automobile to comfort, energy-saving and automation, the neodymium magnet used in automobile motor will increase.
In addition to automotive applications, hard disk drives have the high application of bonded NdFeB. The world has entered the information age. The improvement and development of magnetic storage technology and hard disk drive technology will certainly bring about the development of large data storage industry, and the global demand for hard disk will remain stable. And the development of cloud computing has a higher requirement for massive data, massive storage and massive management of computers. As an important medium of magnetic storage technology, the hard disk is one of the most important data storage methods. It will develop with the development of cloud computing. This will bring a large market for bonded neodymium magnets for the hard disk.
Moreover, the emergence of ultra-thin hard drives brings new opportunities for bonded neodymium magnets. To counter the impact of SSDs, several of the world’s largest hard disk manufacturers are planning to develop ultra-thin hard disks to meet the increasing popularity of the tablet computer market demand, the development of ultra-thin hard disks will bring new opportunities for hard disk magnets.

hard disk
With the rapid development of modern science and technology, we have experienced the full progress of all walks of life in the enjoyment of the rapid development of science and technology, but also in all walks of life can improve the efficiency of the method. No matter how the development of science and technology, our life and work are inseparable from the motor, it is natural to use motor tiles. So the development of magnetic tile in science and technology is also very important.
Every day we work off the means of transportation, the need to drive the motor vehicle movement, the motor in the shoulder of energy conversion at the same time also shoulder the efficiency and safety and other tasks. Among them, the motor magnetic tile is also very important. According to the actual needs, the magnetic tile has a variety of shapes and styles.
Modern tiles are made of permanent magnets, on the one hand, the magnetism will not disappear, basically achieving permanent use. You can assume that if it’s not a permanent magnet, if there’s a loss of magnetism or a loss of magnetism in the process of application, the consequences can be imagined, not much impact and damage, but a car or an aircraft is the entirely different concept.
In addition, the magnetic tile is now required to be able to withstand high temperature, if the motor heating caused damage to the magnetic tile, also in some heavy industry or high-tech areas will cause inestimable losses, so the more important our motor tile is, the more need to ensure its safety and performance. Of course, in today’s high-tech, the industry has been very standardized, magnetic tile development has been able to meet the needs of industry development.