Abstract

An adaptive voltage controller scheme for flux-weakening control under the six-step operation of the Permanent Magnet Synchronous Machine (PMSM) drives is propose in this paper. In the presented technique, the voltage feedback control is applied to fully utilize the DC link voltage, consequently extending the maximum torque range in the flux-weakening region. The behavior of a voltage controller is analyzed under the effect of modulation delay and nonlinear-gain characteristics of six-step operation. Subsequently, a compensatory control action is generated with varying voltage feedback gains based on the magnitude difference between the voltage vectors. This action maximizes the gain of the voltage controller as a function of current vector magnitude and the voltage angle to achieve a greater torque range and higher efficiency in the flux-weakening zone. Features and effectiveness of the proposed technique were verified by simulation and experimental results on a PMSM drive platform.