A New and Fast Method for On-line Estimation of d and q Axes Inductances of Interior Permanent Magnet Synchronous Machines Using Measurements of Current Derivatives and Inverter DC-Bus Voltage

Abstract

This paper proposes a novel on-line technique for estimation of the inductances of an interior permanent magnet synchronous machine (IPMSM) based on the measurement of dc-bus voltage of the inverter and the stator current derivatives at certain voltage vectors during each pulsewidth modulation (PWM) cycle. This technique removes the requirement for the bulky and expensive shaft-locking mechanisms and test signal injection for obtaining the machine dq inductance parameters off line. It also overcomes the problems associated with other recursive on-line techniques which take a number of PWM cycles to update the parameters. The proposed method estimates the d and q axes inductances of IPMSMs within each PWM cycle without requiring knowledge of stator resistance, rotor flux linkage, and rotor speed. It also tracks the variations of the inductances (especially the q -axis inductance), which vary significantly due to q -axis magnetic saturation and cross saturation effect of the IPMSM, with sufficient accuracy. This paper presents full analysis, system simulation, and extensive experimental studies in order to verify the accuracy, quick tracking ability, and robustness of the proposed method.