Hirokazu Nagura

New vector controller for PM motors which modeled the cross-coupling magnetic flux saturation

A new magnetic-flux saturation model has been developed for permanent magnet synchronous motors. In the new model, simple first-order functions Φd(id, iq) and Φq(id, iq) express the relationships between d-q axis currents and each axis magnetic flux, considering magnetic saturation and cross-coupling effects. Taking advantage of these new features, we developed a current controller that introduced the precise inverse model of the motor using the above function. Furthermore, simulations of the proposed current controller were evaluated under ideal conditions without any modeling error. Moreover, it showed, in principle, that the ideal first-order lag characteristic without the current interference between d-q axes could be realized in the conditions of cross-coupling magnetic flux saturation.

Motor drive system using nonlinear mathematical model for permanent magnet synchronous motors

We have developed a mathematical model for permanent magnet synchronous motors (PMSMs). The nonlinear characteristics of this model are expressed using a total of eight constants. The magnet flux characteristics of PMSMs can be obtained by using this simplified model. This model can also be transformed into a reverse function, and motor drive simulation including nonlinear characteristics can easily be implemented. Here, we present the simulation results using our nonlinear model. We also demonstrated the effectiveness of the model by simulating estimates of rotor positions based on magnet flux nonlinear characteristics.