Sensorless Vector Control of Induction Machine with Low Speed Capability using MRAS with Drift and Inverter Nonlinearities Compensation

摘要

The performance of sensorless vector control schemes is seriously degraded at low speed operation, becoming impossible to operate constantly at standstill. There are three main reasons for this degradation in low speed senseless performance. First, offset on the estimation of the back-EMF that causes drift in the open integration of the stator model of the machine. Second, unaccounted nonlinearities of the inverter distort the back-EMF estimation. Finally, errors on the estimated machine parameters, mainly stator resistance cause phase error on the back-EMF estimation. This paper deals with the first two phenomenon to achieve sensorless stator flux orientation and speed feedback by means of an MRAS observer, down to fractions of a Hertz.