The objective of this paper is an analysis method for traction motor which targeting to electric bus and trailer. The type of the studied motor is IPMSM(Interior Permanent Magnet synchronous motor) which has delta type magnet topology of the rotor. It is possible to maximize reluctance torque and output characteristics by arranging the permanent magnet arrangement of the rotor in delta shaped.
Conventionally the two main methods for analyzing electrical machines include magnetic equivalent circuit(MEC) and finite element method(FEM). Whereas FEM is a very accurate yet computationally expensive method, the MEC method has the advantage of faster calculation speed and more feature variables can be considered. Therefore, it can be combined with optimal design algorithms. However, its main disadvantage is the poor accuracy of characteristics analysis as there are many considerations when using MEC method.
Because IPMSM operates in magnetic saturation region, the magnetic saturation characteristics of the iron core are nonlinear and the change in operating current is significant. In addition, because it is a method of expressing a motor with a few lumped constant circuit, there are many errors and more circuit constant or correction factors should be used to solve them. For the above reasons, it is difficult to analysis the motor using the conventional MEC method. To compensate for the inaccuracy of the conventional MEC method without taking into account the magnetic saturation, this paper will show an active MEC analysis method which actively changes according to saturation conditions. It will be implemented as an active function to segment the magnetic equivalent circuit in the rotor’s saturated area into variable resistance, so that it is actively set up according to the load. This will allow to increase accuracy and reduce costs and time. Method will be verified by comparison with FEM and conventional MEC method.