Adaptive Voltage Controller for Permanent Magnet Synchronous Motor in Six-step operation

An adaptive voltage control scheme in flux-weakening control is proposed for permanent magnet synchronous motor (PMSM). Voltage feedback control is applied to utilize the DC link voltage, and maximum torque range for flux-weakening region is extended. The analysis of voltage controller is carried out, taking into account of modulation delay and non-linear effect of six-step mode limitation, to issue the compensation performance with different voltage feedback gains from difference between the magnitude of voltage vectors. Based on those feedback voltage paths, the gain of voltage controller is optimized as an adaptive value by current vector and voltage angle to lead to a larger torque range and system efficiency in flux-weakening region. Dynamic performance and whole flux-weakening stable operation can be implemented with the proposed adaptive voltage control. Verifications are carried out on a 7kW PMSM drive system to prove the features and effectiveness of the proposed technique.