Examination of PMSM Vehicle Generator

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Dr. Balázs Gergely György
Department of Electric Power Engineering

In this thesis I write about the examining calculations if a three-phase permanent magnet synchronous machine. The objective of my calculations is to determine if the machine is capable of delivering a constant power of 10kW to a vehicles DC circuit of 56 V voltage. I got the models of the vehicle generator in development from the Prestolite company, so I based my examinations on them.

In my work firstly, I summarize the basic requirements for a vehicle generator, in particular respect for synchronous alternators. The machine is an Interior Permanent Magnet Synchronous Machine regarding the rotor, so I examine the benefits and disadvantages of this specific type.

As for the next step I examine the air-gap magnetic flux density based on the finite element simulations I ran, and calculate the first harmonic of it. As for the special placement of the permanent magnets in the V-form I present how 40-50% of its magnetic flux becomes leakage flux through the rotor itself.

I compare the results of my analytic calculations and of the simulations by examining the magnetic circuit of the machine, and the working point of the magnets. I calculate the inductances and impedances of the generator and draw the electrical equivalent circuit as well as the phasors of it.

After calculating the AC resistive losses, the iron losses and the mechanical losses I determine the efficiency of the electrical machine. Regarding the results I compared them to other pole shoe vehicle alternators and realized that the generators parameters are acceptable, but not ideal. As most part of the losses greatly depend on the revolution of the machine I conducted my calculations again with two major changes in the models. After decreasing the revolution and increasing the tangential width of the magnets I found growth in the efficiency as much as 20%.


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