Multi-phase motor models analysis in Transient Magnetic
Multi-phase motor can be interesting for many application as they present various advantages such as reduced torque ripple, better reliability, reduced components cost, etc. This kind of topology become more and more trendy. This article will present some new developments in Flux 2022.2 that will help you in your design phase.
Phase variation of an e-motor model
A first analysis of multi-phase motor will show the influence or the phase number on the functioning of a machine. In Figure 1, you can see different IPM models which present the same rotor and dimension but different stator phase number.
Figure 1 - Various phase models
This projects have been solved in transient magnetic. That way, it is possible to study the influence of phase number on various electromagnetic parameters : Magnetic flux density and magnetic field (figure 2), BackEMF (figure 3) and torque (figure 4).
Figure 2 - Magnetic flux density and magnetic field comparison
Figure 3 - Back EMF Comparison
Figure 4 - Torque Comparison
On figure 4, we can easily see the advantage of using multi-phase motor on torque. Indeed, torque amplitude has been slightly increased (225Nm for 3phases vs 295Nm for 7phases). Also, torque ripple has been reduced (50Nm for 3phases vs 30Nm for 7 phases).
Look Up Table and Efficiency Maps Computation Macro for n-phases Motor Models
Another new feature in the 2022.2 version of Flux is an adaptation of the CreateLookUpTableFromTMProjectDQLight macro for supporting any number of phase. You will find in your macro directory a new macro called CreateLookUpTableFromTMProjectDQ_nphases that computes Look-Up Table for n-phases motor.
Macro presentation
Those macros create look up table of FluxD, FluxQ, LD, LQ, and torque versus ID, IQ and rotor position. It will create a new Magneto-Static project from the magnetic transient one. In the Magneto-Static project the current is driven with ID and IQ allowing to extract easily all the needed tables.
CreateLookUpTable calls two other macros to create the DQ system and the solving scenario that drives the motor in the DQ System:
Look up tables of the 7-phases motor model
Appart from the MS solved project, another output of the macro is an oml file that displays Ld, Lq and torque versus Id and Iq with Altair Compose (see figure 7). Also, it generates a .mat file that you may use for your system analysis in Activate or PSIM or any other software.
Figure 7 - Look Up Tables of the 7-phases motor
Efficiency maps of the 7 phases model
This macro results can also be used as inputs in the Compose script found in the Macros_AFIR_machine directory, to plot efficiency maps of your machine (see figure 8). First, you need to modify the Flux_D.oml and Flux_Q.oml input files and add your values of Flux_D and Flux_Q obtained by the macro. Then, the “represent_maps.oml” script launches the computation, and your efficiency tables are plotted.
Figure 8- Efficiency maps of the 7 phases model
All those computation steps represent a good first reduced model of your motor and can be used on many different topologies.
Those files will be standard in the Flux 2022.2 version. The CreateLookUpTableFromTMProjectDQ_nphases can be found in the Macro directory (…\flux\Extensions\Macros\Macros_MultiPhaseMotorAnalysis), and the efficiency maps Compose script can be found in the …\flux\Extensions\Macros\Macros_AFIR_Machine\TableDQ\Table_LD_LQ_Light_MultiplePositions.PFM\Compose directory.