To design the control system of PMSM, the state equation by the d-q coordinate system which set d-axis as the direction of the magnet of PMSM is used. Because, by the current of d-axis and q-axis is controlled appropriately, various control systems can be constituted and this coordinate system is convenient. Moreover, since inductance does not change with rotation angles, there is also an advantage that a formula becomes simple. The state equation by other coordinate systems is hardly discussed. In this paper, while summarizing the difference among these coordinate systems, the state equation of the three phase coordinate system in PMSM is proposed. And, the simulation results of the above vector control system using the three phase coordinate and the γ - δ coordinate will be presented.
