A Novel Flux-weakening Control Method with Quadrature Voltage Constrain for Electrolytic Capacitorless PMSM Drives

In electrolytic capacitorless permanent magnet synchronous motor(PMSM) drives, the DC-link voltage will fluctuate in a wide range due to the use of slim film capacitor. When the flux-weakening current is lower than-ψf/Ld during the high speed operation, the flux-weakening control loop will transform to a positive feedback mode, which means the reduction of flux-weakening current will lead to the acceleration of the voltage saturation, thus the whole system will be unstable. In order to solve this issue, this paper proposes a novel flux-weakening method for electrolytic capacitorless motor drives to maintain a negative feedback characteristic of the control loop during high speed operation. Based on the analysis of the instability mechanism in flux-weakening region, a quadrature voltage constrain mechanism is constructed to stabilize the system.Meanwhile, the parameters of the controller are theoretically designed for easier industrial application. The proposed algorithm is implemented on a 1.5 kW electrolytic capacitorless PMSM drive to verify the effectiveness of the flux-weakening performance.

Quantitative Comparison of Partitioned-Stator Machines for Hybrid Electric Vehicles

In this paper,three partitioned-stator(PS)machines,namely the PS flux-switching DC-field(PS-FSDC)machine,the PS-FS hybrid-excitation(PS-FSHE)machine,and the flux adjuster FS permanent-magnet(FA-FSPM)machine are proposed.With different flux-regulating mechanisms,all three proposed machines can offer satisfactory flux-weakening capabilities for wide-speed range operations.Unlike the traditional PS machine that installs the armature windings and the excitation sources in the outer-stator and inner-stator,respectively;the proposed machines purposely swap the installation arrangements.Upon the proposed structure,the FA-FSPM machine can fully utilize the stator core for PM material accommodations.As a result,excellent power and torque densities can be achieved.To verify the proposed concepts,these three PS machines are quantitatively compared based on the hybrid electric vehicle(HEV)specifications.

Design methodology of permanent magnet generators for fixed-pitch tidal turbines with overspeed power limitation strategy

This paper deals with a design methodology of permanent magnets(PM)generators used for fixed-pitch tidal turbines in a marine renewable energy context.In the case of underwater turbines,fixed-pitch tidal turbines could be very attractive and interesting to reduce maintenance operation by avoiding using such a complex electromechanical system for blade-pitching.In this technological case,one of the main control challenges is to ensure power limitation at high tidal current velocities.This control mode can be achieved using the generator flux-weakening.In this context,this paper proposes an original and systemic design methodology to optimize the generator design taking into account the tidal turbine power limitation for high tidal currents velocities.