Input Admittance Model for the Sensorless Controlled Three-Phase Slim DC-link Drive

Sensorless control is an effective method to increase the overall system reliability in adjustable speed drive and reduce the cost for a slim dc-link drive. However such drive system may suffer from instability issue caused by the constant power load operation and also the reduced dc-link capacitance. In order to investigate this problem, the input admittance model of a sensorless controlled slim dc-link drive system is developed in this paper. The developed model can predict the system stability performance in a PMSM or SynRM drive system, and its effectiveness is verified by the simulations and experiments on a SynRM test bench.