抄録
Current source inverter-fed synchronous motors, hereafter we call them commutatorless motors, have come into a wide use in industry as variable speed drives. They can be controlled to give a good to give a good performance as DC motors can and are easy to be maintained as AC motors are.
When this system is used as a variable speed drive, it is important to consider dynamic characteristics as well as steady state ones.
When we consider dynamic characteristics of variable speed drives, two kinds of dynamics should be taken into consideration; one is the electrical dynamics and the other is the electromechanical dynamics. Since a response in electrical dynamics is much faster than that of electromechanical ones, these two dynamics can be discriminated one from another. The electro-mechanical dynamics can be easily obtained from the torque-speed curve of the motor and the torque characteristics of the load. On the other hand, the electrical dynamics can not be easily obtained, since it involves complicated electrical phenomena. However, the electrical dynamics is a very important factor when a high performance of control characteristics like that of DC drives is required of commutatorless motors.
In this paper, first, the transfer function models of commutatorless motors are obtained mainly from the view point of the electrical dynamics and the transfer function model including the electro-mechanical dynamics is discussed later. The models have been derived on the basis of the average behaviours which are represented by continuous dynamic equations. The phenomena during commutation periods are considered to be equivalent with average voltage drops in the circuits. The adequacy of the transfer models has been confirmed by both simulation and experimental results.
The effects of motor parameter on the performance characteristics of the system are also discussed.
