Electromagnetic and Electromechanical Compatibility Improvement of a Multi-Winding Switch Control-Based Induction Motor—Theoretical Description and Mathematical Modeling

Abstract

The main advantages of multi-winding (multiphase) induction machines include reducing torque ripple, decreasing rotor harmonics losses, reducing the current per phase without increasing the voltage per phase, reducing the current harmonics of the DC voltage source, and high fault tolerance. The authors propose a theoretical description for the harmonic content of the DC-link current, magnetomotive force, and electromagnetic torque of a multi-winding induction machine (IM), and an account of the interaction of the time harmonics for the power supply and the spatial harmonics for winding functions is presented. The proposed theoretical analysis has made it possible to substantiate supply-winding schemes for the compensation of higher harmonics (6th and 12th in the DC-link current and the IM’s electromagnetic torque) and the improvement of the electromagnetic and electromechanical compatibility of the multi-winding machine, which are justified according to the proposed theoretical description. Further, a schematic solution for the multi-winding induction motor with electronic changing of the pole number is proposed to provide a reduction in speed ripples at low rotation speeds. This decrease is ensured by increasing the number of pole pairs and increasing the frequency of the supply voltage. Mathematical models of multi-winding switch control-based induction machines are developed using the method of average voltages in the integration step for an investigation of electromagnetic and electromechanical processes. It is shown that the developed models are distinguished by high speed of response and accuracy. This is confirmed by the comparative analysis using known methods and models in the Matlab environment, as well as a comparison of the simulation results with the known results of physical experiments. The results of mathematical modeling show that the use of a multi-winding IM with appropriate supply-winding schemes stands to significantly reduce the ripples of the IM’s electromagnetic torque and DC-link current in the case of using six-step voltage source inverters. This makes this type of inverter suitable for use in a frequency-controlled electric drive as an alternative to using a PWM inverter, which has a negative influence on the IM’s state.

Overview on Permanent Magnet Motor Trends and Developments

“…A generally accepted strategy for reducing their impact in electric vehicles is based on the integration of the inverter supply with the motor part in the same casing [93], sharing a single cooling system and providing an adequate shielding of alternating current high frequency phenomena, enabling avoidance of interference with other electrical and electronic equipment. Nevertheless, high frequency effects exist on the direct current part concerning the battery management system and the link with the inverter that is why various techniques for their mitigation and attenuation have been proposed, such as appropriate filter topologies [94], combined with switching techniques [95,96], as well as multi-winding machine configurations [97]. It may be noted that a detailed analysis of EMC and EMI effects is critical in particular applications involving very restrictive requirements such as in aerospace engineering [98,99].…”

An Influence of Spatial Harmonics on an Electromagnetic Torque of a Symmetrical Six-Phase Induction Machine

“…Expression ( 2) is obtained taking into account the trigonometric transformations described in [24].…”

“…In the case of the non-sinusoidal supply of 6PIM windings (using Voltage Source Inverters), the expression for the MMF will contain additional components caused by the influence of time harmonics on the winding supply. The interaction between the time harmonics of the winding supply and the spatial harmonics of the winding function is analytically analyzed in [24].…”

“…There are two types of stator winding structure used for six-phase induction machines (6PIMs): an asymmetrical stator winding structure with two three-phase windings spatially shifted by 30 electrical degrees, and a symmetrical stator winding structure with two three-phase windings spatially shifted by 60 electrical degrees. The advantage of the asymmetrical 6PIM is the elimination of the 6th harmonic of electromagnetic torque, which is caused by the interaction between the 5th and 7th spatial harmonics of the winding function and the 1st harmonic of the stator current in the case of the sinusoidal supply voltage [24]. The symmetrical 6PIM provides better opportunities from the perspective of control influence forming [25][26][27].…”

Dynamic Modeling Approach in View of Vector Control and Behavior Analysis of a Multi-Three-Phase Star Permanent Magnet Synchronous Motor Drive

“…This kind is particularly appealing since it can be powered by regular three-phase inverters. Recently, there has been a considerable rise in the research on this specific sort of multi-phase machine [1][2][3]. Due to the specificity of this type of structure, different coordinate transformations can be chosen: one is the coordinate transformation of the dual three-phase motor considered as a whole, i.e., based on the harmonic-based vector space decoupling (VSD) technique, proposed by Lipo [4] in 1995, and the other is the dual dq decoupling method proposed by Radu in 2003.…”