Enhancement of Sensorless Control for Non-Sinusoidal Multiphase Drives-Part I: Operation in Medium and High-Speed Range

This two-part study proposes a new sensorless control strategy for non-sinusoidal multiphase permanent magnet synchronous machines (PMSMs), especially integrated motor drives (IMDs). Based on the Sliding Mode Observer (SMO), the proposed sensorless control strategy uses the signals (currents and voltages) of all fictitious machines of the multiphase PMSMs. It can estimate the high-accuracy rotor positions that are required in vector control. This proposed strategy is compared to the conventional sensorless control strategy that applies only current and voltage signals of the main fictitious machine, including the fundamental component of back electromotive force (back EMF) of non-sinusoidal multiphase PMSMs. Therefore, in order to choose an appropriate sensorless control strategy for the non-sinusoidal multiphase PMSMs, these two sensorless control strategies will be highlighted in terms of precision with respect to rotor position and speed estimation. Simulations and the experimental results obtained with a non-sinusoidal seven-phase PMSM will be shown to verify and compare the two sensorless control strategies. In this part of the study (part I), only sensorless control in the medium and high-speed range is considered. Sensorless control at the zero and low-speed range will be treated in the second part of this study (part II).

GA Optimization for Regression Modeling of Electromagnetic Performances Predicted by a Subdomain Model for SMPMSM in an Electric Vehicle

This paper investigates a nonlinear modeling optimization of 12s/8p surface-mounted permanent magnet synchronous machines (SMPMSM) with a radial magnetization pattern. The modeling is based on subdomain model (SDM) computation, where the analytical models are developed to predict the electromagnetic (EM) performances, such as, average EM torque and EM torque ripple in PM machines. A genetic algorithm is applied to the proposed model in order to search for the optimal solutions. The objective function of the optimizations is obtaining a higher average EM torque and achieving the minimum EM torque ripple. The data, viz, and the average EM torque and its ripples predicted by SDM are employed in regression analysis in order to find the model of best fit. After that, the most suitable fit of the computing equation is selected. The preliminary and optimal designs of 12s/8p PM motors are also compared in terms of parameters and motor performance. As a result, the regression model and GA framework has reduced the use of magnet materials and the EM torque ripple of the SMPMSM, making it ideal for use in an electric car. Lastly, the proposed model can determine the appropriate configuration design parameters for SMPMSM in order to achieve the best motor performance.

A Novel Approach to Transverse Flux Machine Construction

The article presents a concept for a new design of the well-known Transverse Flux Machine (TFM) made with the use of a flat core used in classical electrical machines. The proposed design was first analytically verified and was subsequently verified using the finite element method, which fully corroborated the results. The simulations show that a set of three single-phase TFM machines with slotted flat rotor yokes generates a torque over three times greater than that of an induction motor and twice as large as Fractional Slot Concentrated Winding—Permanent Magnet Synchronous Machines (FSCW-PMSM). The performed comparative calculations confirmed that the torque generated by machines operating on principles similar to TFM can generate a torque much greater than those currently in common use.

Analytical Model to Calculate Radial Forces in Permanent-Magnet Synchronous Machines

There are three principal sources of noise and vibration in electrical machines: electromagnetic sources, mechanical sources, and aerodynamic sources. Nowadays, one of the major advantages of permanent-magnet synchronous machines is their torque density. This density is achieved through a high magnetic flux density in the air gap, which is achieved through hard magnets. Unfortunately, in these machines, electromagnetic forces have been identified as the main source of vibration and noise, and high magnetic flux densities make these vibrations and noises more significant. With the aim of better understanding the relationship between electromagnetic forces and design variables, this article, which is the continuation of previous work, firstly describes a study of the sources of magnetic forces in permanent-magnet synchronous machines. Subsequently, an analytical model for the computation of the radial forces originating from electromagnetic sources in permanent-magnet synchronous machines is stated. This model analyzes the forces on both the rotor surface and the base of the stator tooth. The analytical results were corroborated through simulations using the finite element method (FEM) and also by experimental tests performed over two prototypes. The results achieved by the analytical model show good agreement with both FEM results and experimental measurements.

Advances in Dual-Three-Phase Permanent Magnet Synchronous Machines and Control Techniques

Multiphase electrical machines are advantageous for many industrial applications that require a high power rating, smooth torque, power/torque sharing capability, and fault-tolerant capability, compared with conventional single three-phase electrical machines. Consequently, a significant number of studies of multiphase machines has been published in recent years. This paper presents an overview of the recent advances in multiphase permanent magnet synchronous machines (PMSMs) and drive control techniques, with a focus on dual-three-phase PMSMs. It includes an extensive overview of the machine topologies, as well as their modelling methods, pulse-width-modulation techniques, field-oriented control, direct torque control, model predictive control, sensorless control, and fault-tolerant control, together with the newest control strategies for suppressing current harmonics and torque ripples, as well as carrier phase shift techniques, all with worked examples.

Investigation and Experimental Validation of Sideband Harmonic Vibration of IPMSM with and without Skewed Slots for EVs

Due to their advantages of high power density and high efficiency, permanent magnet synchronous machines (PMSMs) are widely used in the field of electric vehicles (EVs). Vibration and noise are important indicators for evaluating the performance of PMSMs, and the skewed slot method is now widely used to mitigate the torque ripple and noise of motors. In the vector control strategy, the space vector pulse width modulation (SVPWM) method produces sideband voltage harmonics with a frequency near the switching frequency. These harmonics act on the magnetic field to generate an excitation force with a frequency near the switching frequency. This paper compares and analyzes the sideband harmonic current and the exciting force of a skewed slot motor and a straight slot motor during steady-state operation. The research results show that the skewed slot method can effectively mitigate the vibration and noise caused by sideband harmonics.

Design Optimization of Multi-Layer Permanent Magnet Synchronous Machines for Electric Vehicle Applications

This paper presents a comparison between two design methodologies applied to permanent magnet synchronous machines for hybrid and electric vehicles (HEVs and EVs). Both methodologies are based on 2D finite element models and coupled to a genetic algorithm to optimize complex non-linear geometries such as multi-layer permanent magnet machines. To reduce the computation duration to evaluate Induced Voltage and Iron Losses for a given electrical machine configuration, a new methodology based on geometrical symmetries and magnetic symmetries are used and is detailed. Two electromagnetic models have been developed and used in the design stage. The first model was the stepped rotor position finite element analysis called abc model which considered the spatial harmonics without any approximation of the waveform of flux linkage inside the stator, and the second model was based on a fixed rotor position called dq model, with the approximation that the waveform of flux linkage inside the stator was sinuous. These two methodologies are applied to the design of a synchronous machine for HEVs and EVs applications. Design results and performances are analyzed, and the advantages and drawbacks of each methodology are presented. It was found that the dq model is at least 5 times faster than the abc model with high precision for both the torque and induce voltage evaluation in most cases. However, it is not the case for the iron losses computation. The iron loss model based on dq model is less accurate than the abc model with a relative deviation from the abc model greater than 70% at high control angle. The choice of the electromagnetic model during the optimization process will therefore influence the geometry and the performances of the obtained electrical machine after the optimization.