Experimental Identification of Induction Machine Flux Maps for Traction Applications

Nowadays the permanent magnet machines are a widespread solution in the automotive field. However, the induction machine (IM) represents a valid solution as it is rare-earth free and does not have induced stator back-emf in case of inverter turn-off. Regardless of the machine type, identification procedures are needed for torque control calibration and for optimal machine utilization in terms of efficiency and maximum torque production under inverter current and voltage constraints. For synchronous machines, a common and consolidated practice is to obtain the machine flux maps (current-to-flux relationship) in the rotor (d,q) frame using calibrated Finite Element Analysis (FEA) or experimental procedures. However, to the best of the authors' knowledge, the literature does not report an experimental approach able to obtain the flux maps for IMs. Therefore, this paper proposes an experimental procedure to obtain the IM flux maps in (d,q) rotor flux frame for inverter supply and real operating conditions. In addition, the proposed procedure is able to obtain the parameters of the IM equivalent circuit with no need of additional tests. Experimental validation is provided for a 4-poles IM rated 10 kW, 200 Hz

Magnetic Model Identification of Multi-Three-Phase Synchronous Motors

Multi-three-phase motor drives are experiencing a significant development among the multiphase solutions since they are configured as multiple three-phase units operating in parallel. Although the literature reports several torque controllers able to deal with multi-three-phase motors, most of them obtain high performance of torque regulation as long as flux and torque maps of the machine are known. The literature currently reports very few contributions dealing with the experimental identification of flux and torque maps of multi-three-phase synchronous motors operating in healthy and open-three-phase fault conditions. In addition, almost all these research contributions focus on dual-three-phase machines. This paper thus proposes an experimental test procedure to directly identify the flux and torque maps of a multi-three-phase synchronous motor featuring an arbitrary number of three-phase winding sets. The proposed identification procedure also allows an accurate machine analysis considering all potential open-three-phase fault scenarios. Experimental results obtained on a 12-phase interior permanent magnet synchronous motor using a quadruple-three-phase configuration of the stator winding are presented. Besides, flux and torque maps obtained in severe open-three-phase fault conditions are shown, fully validating the proposed identification procedure

Flux Polar Control (FPC): a Unified Torque Controller for AC Motor Drives

Transportation electrification is leading to an impressive development of electric drives (eDrives) using either synchronous- (SM) or induction- (IM) motors. However, these eDrive solutions need high-performance torque controllers that must be easy to tune and able to deal with saturated machines. Besides, the torque regulation must be linear for the entire operating speed range, including deep flux-weakening (FW) operation with maximum torque per volt (MTPV) limitation. According to the current state-of-the-art, the torque controllers for traction applications are mainly based on control schemes like current vector control (CVC), direct torque control (DTC), or the more recent direct flux vector control (DFVC). However, these solutions employ inner control loops whose performance depends on the machine's inductances, thus requiring the execution of demanding tuning procedures to adapt the control parameters to the machine's operating point. Moreover, CVC-based torque controllers sometimes rely on demanding multidimensional calibrated maps to linearize the torque regulation and simultaneously perform FW operation with MTPV. In contrast with the torque control solutions mentioned above, this article proposes a unified torque controller for ac motors based on inner flux- and load angle- control loops since their performance is independent of the machine's inductances, i.e., magnetic saturation phenomena. Also, the torque linearization relies on a simple calibrated map providing maximum torque production under inverter current- and voltage- constraints. Experimental results are presented for four different eDrives using both SMs and IM, validating the unifying feature and demonstrating the high dynamic performance of the proposed torque controller