2001 Volume 37 Issue 5 Pages 389-396
A synchronous motor (SM) with q-axis special field-winding of which q-axis field-current compensates and cancels armature reaction can be driven at unity power factor on condition of transient process as well as steady state. The motor operates in high efficiency on all conditions due to unity power factor similar to characteristics of DC motor. However, in order to extract maximum performance of the motor, it is required that the time constant of armature circuit corresponds to that of q-axis field circuit. Inverse LQ (ILQ) design method on a basis of the pole placement is suitable for this problem: (1) the time constants of the output responses can be designed for desired specifications, (2) relations between feedback gains and response of closed loop system are very clear and (3) optimal solutions can be given by simple procedure of ILQ method without solving the Riccati equation, compared to the usual LQ design method. The responses of armature current coincide with q-axis field-current, so that we can realize a high-performance motor with unity power factor and high efficiency. In this paper, it is proved that ILQ design method is very effective for optimal regulator design for the plant and gives excellent characteristics by numerical simulations and experiments.
