Research On An Asymmetric Armature Current Control Strategy Of Wound-Field Doubly Salient Motor

Wound-field Doubly Salient Machine(WFDSM) enjoys excellent benefits of simple structure, controllable excitation, wide speed range and flexible control so it performs well in speed-adjusting applications. This thesis mainly researches on asymmetric armature current control(AACC) system of four-phase WFDSM. Aiming at disadvantages of original full bridge control system for low-speed WFDSM with large phase inductance: low rising rate of armature current, large current peak, low output torque with large ripple and low efficiency, an AACC system including new H-bridge topology and corresponding four-phase sixteen-state strategy are proposed. It lays the groundwork for application of low-speed WFDSM speed-adjusting system.First of all, this thesis introduces structure and working principles of four-phase WFDSM as well as derives its mathematical models. Changing rules of WFDSM electromagnetic force are analyzed by using 2-D finite element analysis(FEA). Furthermore, principles of WFDSM half-cycle control(HCC) are analyzed and verified.Secondly, problems of low-speed WFDSM original control strategy are analyzed and principles of output torque under different current values are obtained by using 2-D FEA. H-bridge topology and corresponding four-phase sixteen-state strategy are put forward on the basis of reference current value computational formula which come from magnetic energy curves. Finite element co-simulation models consist of ANSYS and Matlab are established based on a 8/6 WFDSM prototype. System open-loop characteristics of standard angle control(SAC), advanced angle control and widened conduction interval are simulated.Control system based on NI LabView and FPGA board is built according to control strategies above as well as designing processes of hardware or software parts are elaborated. Experiments including mechanical characteristics and realitiesof stable closed-loop operating are accomplished by using test bed constructed. Results show that: low-speed WFDSM output torque and efficiency can be enhanced well through AACC as well as speed-adjusting system has robust capabilities.