MagNet Plug-in for SPEED: Designing an IPM motor with fractional slot
This example will demonstrate the use of the MagNet Plug-in for SPEED in the design of an interior permanent magnet (IPM) motor with fractional slot. Use of this Plug-in within the SPEED application effectively combines the advanced electric motor design software of SPEED with the powerful calculation capabilities of MagNet. Based on the desired output, the SPEED PC-BDC program produces a preliminary design. Given this design, the user may then wish to obtain accurate motor characteristics before making any further modifications. To accurately determine the motor characteristics, PC-BDC provides a number of functions that make use of the electromagnetic field solver in MagNet. These functions are called GoFERs (go to finite-elements and return). The GoFER functions invoke MagNet's static 2D solver through the MagNet Plug-in for SPEED to solve the electromagnetic field problem, obtain the required results and then display them to the user in PC-BDC. With the Plug-in, all processes pertaining to MagNet run in the background, leaving the PC-BDC program to remain as the active application.
Under study is a 15-slot, 4-pole IPM 3-phase sinewave supplied brushless dc motor. The shorted magnet arrangement in this motor gives rise to high local saturation in the bridges, necessitating accurate modeling of nonlinearity, only possible from a finite element solution.
The example presented here describes the use of a particular GoFER in PC-BDC called I-psi. Once the i-psi loop data are obtained, the user can adjust the PC-BDC parameters.
SPEED PC-BDC
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SPEED interface and how the GoFER works
From the Tools menu in PC-BDC, the user can access a number of GoFER functions, including "i-psi calculation". The graphic to the right shows all the different GoFER functions available in PC-BDC. Once "i-psi calculation" is selected, the user is given a number of other options, including ones that specify range of currents, range of advanced phase angles and number of rotor positions, before MagNet is automatically launched to solve the associated electromagnetic field problems.
i-psi results
Once the field solutions in MagNet are complete, the flux linkages are automatically calculated and fed back to PC-BDC along with the other results, all of which requires no interaction by the user. These results can then be examined in PC-BDC, as shown in the three graphics that follow.
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MagNet results
The MagNet file that is generated during this process is not discarded, making the entire model, along with the solutions, available to the user for further analysis within MagNet. Some examples of these results are shown below.
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