How do I design a Permanent Magnet Synchronous Generator?

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1. Mar 19, 2017

patodwyer

Hi,

I'm trying to do a very simple analysis on Simulink where I am applying a speed to a Permanent Magnet Synchronous Generator with a purely resistive load.

I'm not familiar with PMSGs so the results I'm getting don't really make any sense to me. Could any one go through some simple design calculations so I can get a better grasp? Most of what I'm coming across online seems very heavy theory wise and not explained in a simple manner.

I want to understand the terminal voltages and currents mainly.

Last edited: Mar 19, 2017
2. Mar 20, 2017

jim hardy

It's difficult for us to guess at what you need. Are you familiar with phasor notation?

That's the trouble with computer simulating programs for teaching, they allow a student to jump right to results with no idea of how he got there.

A permanent magnet synchronous machine can be treated as just a synchronous machine machine with its field excitation locked at one value.

In absence of armature current , Terminal volts = KΦRPM where
K is a machine constant determined by open circuit test
Φ is flux in the machine, field excitation ( note that's at zero armature current)
since your permanent magnet machine has fixed field excitation you can consider KΦ a single constant
and RPM is of course speed.

When armature current is allowed to flow terminal volts will be lower because of IR drop in armature windings and a magnetic phenomenon known as "Armature Reaction"

Armature Reaction is usually expressed as "Synchronous Impedance" , let me call it Zsynch , a characteristic of the machine that you determine by a short circuit test.
So, in presence of armature current terminal volts is approximately equal to KΦRPM - Iarmature X Zsynch , neglecting leakage, resistance, and magnetic non-linearity of iron ,.....

So your design is multi step
mechanical - size and shape
magnetic - air gap, length and area of magnetic path, what alloys to use, how much MMF do you need
electrical - how much wire of what size
thermal - move enough air through it to remove heat from core and windings

all four interact so it's an iterative process. The formulas you're finding include shortcuts that designers use so as to not start from these basics every time.
First time through you do need to start from those basics so as to understand what's going in inside the machine.

https://www.physicsforums.com/threa...us-alternator-varying-pf.903012/#post-5686865