Hello, friends, I hope all of you are enjoying your life. In today’s tutorial, I am going to explain Permanent Magnet Synchronous Generator. The synchronous generator is such a device that transforms mechanical energy into the electrical energy delivered by the prime mover of the generator. It is also known as an alternator. It called a synchronous generator because its rotation speed is equal to the rotating speed of the field at the stator of the generator called synchronous speed. In this generator, external supply is provided to excite the generator that is the reverse of the induction generator. For excitation, the external dc source is connected to a synchronous generator.
In today’s post, we will have a look at another type of synchronous generator that called permanent magnet synchronous generator. In this generator, there is no need of a separate dc source for the excitation of the generator. We will describe the working principle, applications, advantages, disadvantages, and some other related parameters of this generator. So let’s get started with the Permanent Magnet Synchronous Generator.
Permanent Magnet Synchronous Generator
- The permanent magnet synchronous generator called so because in this synchronous generator excitation is provided with the permanent magnet instead of the external excitation source.
- Its rotor is consists of the permanent that generates a field for excitation and replaces the external supply source for the generator.
- In most of generation power plants, the synchronous generator is used. In steam turbines, hydro turbines, and in gas turbines synchronous generator is used.
- Like other generators, the physical structure of this generator is the same it also consists of the rotor which also comprises of the permanent magnet with the shaft connected with it.
- Like stator of other generators, this generator also has a stator that provides protection to internal structure from the exterior environment.
- In permanent synchronous generator, there is no need of the slip rings and carbon brushes, which make the machine less expensive, lightweight, and maintenance of the generator also decreases.
- But in high rating generators, large size generators are used that make machines somewhat expensive and increases the price.
- The generator attached with the power electronic conversion circuitry can work on the less speed and so there is no need of the gearbox.
- The presence of gearboxes increases the price, energy losses, and cost of repairing the generator but without the gearbox price and weight of circuitry deceases but it also the best option for the offshore applications.
- With the direction of flux lines, the permanent synchronous generator is divided into three categories first one is the radial flux permanent magnet synchronous generator, the second one is the axial flux permanent magnet synchronous generator and the third one is the transverse flux permanent synchronous generator.
What is Synchronous Speed
- PMSG is called synchronous generators since the voltage produced frequency in the stator or armature calculated in the hertz is directly the proportion to rotation cycles of the rotor.
- The formula to find the synchronous speed is 120 (fe/P).
- In this equation, the fe is the frequency of the voltage induced at the stator.
- P is the no of a pole in the generator.
Working Principle of Permanent Magnet Synchronous Generator
- The working of the PMSG depends on the field produced by the permanent magnet attached at the rotor of the generator for the conversion of mechanical energy into electrical energy.
- Like synchronous generator in PMSG, there are two types of windings first one is the armature that is wound on the stator and the second one is the field winding that is wound on the rotor.
- At the stator of generator 6 soils of copper, windings are wound and fixed at their respective places.
- The rotor that has a permanent magnet is connected to the bearing rotating on the shaft. In this generator, there are 2 rotors first one is behind the stator and second one is at the exterior side.
- Both of these are connected with each other through the long studs moving by the hole in the stator.
- The blades are also surfaced on these studs that connecting the rotors with each other.
- These blades rotate the rotor for the production of electrical energy.
- In the given figure you can see the construction of the generator.
Applications of Permanent Synchronous Generator
- These are some applications of the permanent magnet synchronous generator.
- It used to provide the power for the excitation of the high rating synchronous generator.
- During the short circuit, these generators provide the power to the generator connected in the system to maintain the required voltage for the system.
- It also used in such power generation systems where wind turbines are used.
So friends that is the detailed post on the permanent magnet synchronous generator I try my level best to simplify this article for you and explained each and every parameter related to generator. If you have any further queries about this post as in comments. I will guide you further. See you in the next tutorial. Thanks for reading.
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Hello, Great to read your articles and discussions about Permanent Magnet Generators. Thank you for those.
I am an “inventor” with a multitude of practical and theoretical skills.
I am building a micro hydro water turbine in the hills to produce 3 – 5 Kw of electricity off grid.
The hydraulic system is in place and I have purchased a three phase 380v Permanent Magnet Alternator. The system is to run into purpose designed house heating system consisting of a 1.5kW heat pump and switched domestic heaters. These were to 240v. Single phase to be derived from rectified three phase to 380v DC into a 3 and 2 kw sine wave inverters. to 240v AC.
So I need controllers. to maintain the speed of PMA rotation to the given voltage output.
Then the challenge for the design. Resistive load present no real problem but the heat pump compressor will present on starting- loading issues particularly if in single phase.
So now I am thinking about using a three phase compressor. (A local refrigeration company are to construct a bespoke machine).
If I stay in three phase I will have less losses and the system should be the most resilient to the high milli second loading currents and not stress the sine wave inverter.
If I were to change generator to use a synchronous induction generator with AGC the output voltage and frequency would be automatically controlled and maintained.
But I already have the PMA (suitable for a wind turbine etc) which is classic in internal wiring configuration Star / Delta.
So thanks for reading the long introduction. So at last here is the real question.
Can this alternator be controlled with any kind of constructed AGC with feed back to maintain the frequency as well as the output voltage particularly in the miili-second compressor start up times.
I don’t think the speed variation controller that I will build to switch solid state relays to the resistive loads will react fast enough due to the flywheel effects of the hydraulic system.
I really welcome your advice if you can.
Many thanks.
Very interesting, I need a generator domestic use to provide dc generation supplying a battery pack holding a 20kw capacity via inverter. Where can I buy these ? Any different sizes?