Performance Analysis of Permanent-Magnet AC Servo Motor Driven by Current-Controlled PWM Inverter

Abstract

A current control system is the most important element for a high-performance adjustable-speed control system. One of current control systems that are used now is control method with average value.
In this paper, the equations of proportional integral control circuits are converted to those of the synchronously rotating frame, to adapt the fundamental equations of a permanent-magnet AC servomotor, and a method of exact numerical analysis by the state variable method is proposed. Nominal induced emf is compensated for a change for the worse of the current control that is problem in high speed operation. The results of the nominal induced emf compensation are comfirmed, and the results are compared with those of analysis. Moreover compensation of internal emf is analyzed, and the results of the analysis are compared with those of analysis that a case of only nominal induced emf compensation.
Consequently, following results are given.
(1) Analytic waveforms coincide with experimental waveforms.
(2) In high-speed operation, current control grow worse by equivalence gain drop of current control loops. Especially light loads make control grow worse remarkablly, but emf feedback can compensate for it.
(3) High gain of current control loops effect equivalent results as emf compensation.
(4) The effects of nominal induced emf compensation are approximately equibalence to that of internal emf compensation.