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High Performance Control Techniques for Multiphase eDrives
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Effect of Rotor Type on Open-Set Derating Operations of Multi-Three-Phase Synchronous Machines
No full textMulti-three-phase machines have attracted considerable interest in several fields thanks to the enhanced fault tolerance and the reduced phase current, adopting standard three-phase inverters instead of special custom converters. However, the fault-tolerance and the quality of the derated performance is strongly dependent to the winding topology and the type of rotor adopted. This study compares two 12-phases machines with distinctive rotor structure and magnetic behaviors: one with high anisotropy and low PM content and the other with lower anisotropy and dominant PM flux linkage. Efficiency and torque ripple are included in the comparison, both in healthy and open-set derated conditions. The results shows that derating is not crucial on an average point of view, but can significantly increase the torque ripple and, in some scenarios, to further reduced operating area. Notably, the high-anisotropy machine demonstrates superior field-weakening performance, whereas the motor with greater PM flux linkage achieves better derated output below base speed. These findings highlight the importance of rotor selection in optimizing multi-three-phase drives, according to the specific application
Fast Computation of the No-Load Characteristic for Wound Field Synchronous Propulsion Motors
Get PDFWound field synchronous machines are gaining attention as an interesting permanent magnet-free alternative for propulsion applications. The third degree of freedom introduced by the rotor current makes the electromagnetic design of these machines not trivial. Hence, dedicated and fast analysis tools are necessary to predict the machine behavior. This paper presents a fully analytical procedure for the computation of the no-load characteristic of salient-pole wound field synchronous machines. The procedure considers the iron saturation and includes the magnetic shunt of the stator slots. The distortion of the air gap flux
density waveform introduced by the teeth saturation and the rotor saliency are considered. The procedure has been experimentally validated using a 4 poles, 100 kW peak power wound field synchronous motor
Modular Vector Control of Multi-Three-Phase Permanent Magnet Synchronous Motors
No full textRecent developments in power electronics are making the multiphase machines a competitive alternative to conventional three-phase counterparts. Due to their
fault-tolerant features, multiphase drives represent a robust technology in high power/high current, safety-critical applications. Besides, their introduction into transportation electrification is gaining on importance. Among the multiphase solutions, the multi-three-phase machines are receiving a lot of the attention by the industry since they use the well-consolidated three-phase technology, thus reducing the design time and also the cost. Therefore, this paper proposes a modular vector control scheme for multithree-phase permanent magnet synchronous motors. The
proposed solution uses a modular modeling approach for the independent and decoupled torque control of each three-phase unit, allowing the implementation of torque sharing strategies among the three-phase sets of the machine. The developed modular control has been validated on a nine-phase permanent magnet machine
Accurate Induction Machines Efficiency Mapping Computed by Standard Test Parameters
Get PDFThe extensive electrification process that is taking hold in several applications makes increasingly necessary the virtualization of electric components for energetic and performance assessments during the system design stage. For this purpose, this paper proposes a straightforward methodology for computing the efficiency maps of induction machines operated in wide torque-speed ranges. The modeling approach is based on the induction machine equivalent circuit defined in the rotor dq coordinates. The procedure allows computing a set of efficiency maps at different machine temperatures and supply voltage levels, both for motor and generator operation modes. The equivalent circuit parameters at different frequencies and voltages are determined by means of the well-known no-load and locked-rotor tests, thus including in the modelling the machine nonlinearities, skin effect and the iron losses. The proposed methodology has been validated on a 10 kW, 4-pole induction machine. The comparison between computed and experimental efficiency maps for different operating conditions, confirm the validity of the proposed methodology
An Experimental Test Procedure for Magnetic Model Identification of Multi-Three-Phase Induction Motors
No full textMulti-three-phase motor drives are experiencing increasing industrial development as these multiphase motors can be configured as multiple three-phase units operating in parallel. In this scenario, the literature reports several torque controllers for multi-three-phase motors to guarantee high performance in torque regulation accuracy and efficiency. However, these torque controllers almost often rely on the accurate knowledge of the magnetic model of the machine, i.e., the current-to-flux and current-to-torque relationships. When considering induction motors (IMs), most of the methodologies to evaluate flux and torque maps consist of their indirect computation from the parameters of the machine’s equivalent circuit. However, these parameters are almost always obtained by performing the no-load and locked-rotor tests, i.e., not evaluated in actual machine load conditions. In addition, if considering multi-three-phase IMs, no contributions dealing with the effective flux and torque maps in open-three-phase fault conditions are reported in the literature, making the post-fault analysis a topic not comprehensively investigated. Therefore, this paper proposes an experimental test procedure to directly identify flux and torque maps of a generic multi-three-phase IM. In this way, the magnetic model of the machine is evaluated by considering the actual operating conditions in terms of load/slip. Moreover, the proposed test procedure allows accurate machine analysis in open-three-phase fault conditions. Experimental results obtained on a 12-phase IM using a quadruple-three-phase stator winding configuration are shown, validating the proposed identification procedure
Decoupled and Modular Torque Control of Multi-Three-Phase Induction Motor Drives
Get PDFIn recent years, the development of multi-three-phase drives for both energy production and transportation electrification has gained growing attention. An essential feature of the multi-three-phase drives is their modularity since they can be configured as three-phase units operating in parallel and with a modular control scheme. The so-called multi-stator modeling approach represents a suitable solution for the implementation of modular control strategies able to deal with several three-phase units. Nevertheless, the use of the multi-stator approach leads to relevant coupling terms in the resulting set of equations. To solve this issue, a new decoupling transformation for the decoupled torque control of multi-three-phase induction motor drives is proposed. The experimental validation has been carried out with a modular power converter feeding a 12-phase induction machine prototype (10 kW, 6000 r/min) using a quadruple three-phase stator winding configuration
Off-Line Efficiency Mapping of Induction Motors Operated in Wide Torque-Speed Ranges
Get PDFIn the context of a progressive component virtualization for energetic assessments in variable speed and load operations, this paper presents a methodology for computing the efficiency maps of three-phase induction motors. The proposed approach is based on the conventional machine equivalent circuit to quickly obtain a set of efficiency maps at different machine temperatures and supply voltage levels. The well-known no-load and locked-rotor tests are used to determine the motor parameters at different frequencies and voltages, taking into account the machine nonlinearities and the iron losses. The approach has been validated on an 11 kW, 4 poles, 50 Hz induction motor tested in different operating conditions
About the Evolution of the Iron Losses: From Sinusoidal to PWM Inverter Supply
No full textThe aim of this work is to present the evolution of the specific iron losses concept, in light of the introduction of the power converted supply, introduced in the 80s and currently a standard in the electrical machines supplies. This paper deals with the evolution for the iron losses. It is focused on the main differences introduced by the power converter on the magnetic and energetic quantities, with respect to the traditional sinusoidal sources and their effects on the soft magnetic material and the related iron losses
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