James M. Nagashima

Two flux weakening schemes for surface-mounted permanent-magnet synchronous drives. Design and transient response considerations

Two recently published flux weakening schemes for surface-mounted permanent-magnet synchronous (SMPMS) motor drives have offered estimable advantages over previous solutions. The first scheme uses values of the voltage reference to generate an adequate flux weakening component of the stator current, whereas the second method detects an increase of the tracking error in torque-producing current component and uses the error signal for the flux weakening control. The viability of the algorithms has been demonstrated and the schemes have been compared and analyzed in steady-state operation. The transient behavior is very important for electric vehicles and other high-performance applications. Here, the authors analyze the transient response characteristics of both schemes when a sudden change in the torque reference is received. The paper also describes an approach to practical regulator design and parameter selection for the flux weakening control section.

An application of a constrained adaptive lattice-structure allpass-based notch filter for advanced control of surface-mounted permanent-magnet synchronous drives

A constrained adaptive lattice-structure allpass-based notch filter provides minimal phase delay and complete attenuation of the notch frequency. The allpass sections of the filter are realized as structurally lossless bounded real functions, with a minimum number of delay elements and multipliers. The filter structure admits orthogonal tuning of the notch frequency and notch bandwidth. An improved control scheme for surface-mounted permanent-magnet synchronous (SMPMS) drives ensures stable high-performance operation in the Bur weakening region, utilizing the over-modulation and six-step modes of the space vector modulation (SVM). An automatic transition into the flux weakening region is achieved by controlling the reference voltage magnitude. The fifth and seventh stator current harmonics of the fundamental frequency, generated in the over-modulation and six-step modes, propagate through the current control loops, resulting in the sixth harmonic in the reference voltage for the flux weakening loop and deteriorating drive performance. To properly filter the sixth harmonic over the extended speed range of the drive, the constrained adaptive lattice-structure allpass-based notch filter is employed.

Robust flux weakening scheme for surface-mounted permanent-magnet synchronous drives employing an adaptive lattice-structure filter

An advanced control structure for surface-mounted permanent-magnet synchronous (SMPMS) drives provides a stable, high performance operation in the flux weakening region, utilizing the over-modulation and six-step modes of the space vector modulation (SVM). An automatic transition into flux weakening is achieved by controlling the reference voltage magnitude. The fifth and seventh stator current harmonics of the fundamental frequency, generated in the over-modulation and six-step modes, propagate through the current control loops, resulting in the sixth harmonic in the reference voltage and deteriorating drive performance. To filter the sixth harmonic, an adaptive lattice-structure allpass-based notch filter is employed, providing minimal phase delay and complete attenuation of the sixth harmonic.