Phase Permanent Magnet Synchronous Machine Research Articles

Current Measurement Gain Compensation Using High-Frequency Signal Injection in Dual Three-Phase PMSM Systems

To online compensate the scaling errors in current measurement caused by incorrect calibration, temperature, aging, and noise, this paper proposes a new solution based on high-frequency (HF) carrier voltage injection in dual three phase permanent magnet synchronous machines. The relationship between the measured HF currents and scaling errors is derived. It shows that the amplitudes of the HF currents are proportional to the scaling errors, based on which three HF current control loops are subsequently designed to eliminate the measured HF currents and compensate the scaling errors. The designed HF controller are independent from the main current and torque regulators, and thus, it can be used for initial scaling gain calibration or periodically used during normal machine operation. Different from general three phase machine systems, the generated HF current components only exist in z <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">1</sub> z <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> subspace, and thus, no extra torque ripples will be produced. Experimental results validate the proposed control algorithm.

Toward an optimal twisting-sliding mode control of a three-phase PMSM for electric vehicles

This paper deals with an optimal twisting sliding mode controller (OT-SMC) for the operation of a three phase permanent magnet synchronous machine (PMSM) in an electric vehicle (EV). In order to drive these vehicles, optimal performance is needed with robust control against real-time disturbances such as the variable load torque, uncertainties such as the parameters variation and speed variations between medium, low, and high speed as well as good performance characteristics for enhanced drive quality and longer battery time. Several conventional techniques have been applied to PMSM but they suffer from the problem of uncertainties and disturbances due to the PI regulator. A hybrid approach comprising of a robust nonlinear and optimal controller to achieve these objectives is attempted for driving electrical vehicles. This advanced hybrid controller obtained after the merger of sliding mode control (SMC) and a linear quadratic controller (LQR) is found to outperform existing controllers due to their superb performance characteristics. Furthermore, SMC is designed based on the exponential reaching law for the twisting sliding mode control (T-SMC) in order to ensure stability of the system while reducing the chattering, accelerating the rate of convergence with higher accuracy of the control performance, and the LQR is developed using the steady-state error method (N-LQR) in order to obtaining better performance characteristics. In addition, the hybridization between a twisting SMC and an optimal LQR is characterized by stabilizing and minimizing the oscillations in the permanent regime thus optimizing the system’s performance. Extensive simulation results illustrate the effectiveness and validity of the proposed control for achieving the highest performance of the PMSM.

Optimal switching sequence control for current stress reduction of DC-link capacitors in dual-three phase PMSM drives

The safety and installation space of DC-link capacitor is crucial for dual-three phase permanent magnet synchronous machines (DTPMSM) drives in industrial applications. Reducing the capacitor current stress can contribute to decrease the designed capacitor value and install size, thus enhance safety of drives fed by two parallel inverters. Therefore, an optimal switching sequence control scheme for DTPMSM drives is proposed to reduce the DC-link capacitor current stress in this paper. For DTPMSM drives, the maximum four adjacent voltage vectors control (MFAVC) method is usually adopted due to its control flexible and stability characteristic. Based on MFAVC, the capacitor current can be derived though the current reconstruction theory to reorder the current amplitude over one switching period. Through the rearrangement of voltage vector and duration, the theoretical analysis of capacitor current reduction is presented. On this basis, the optimal switching sequence control method can be implemented based on the minimized current sum of the two inverters. The performance of proposed method has been evaluated via. comparatively experimental tests on a prototype 3 kW DTPMSM drive, which shows superior features on reducing capacitor current stress. Furthermore, it is also found that the proposed method is helpful to redesign a small capacitor value for DTPMSM drives.

Mitigation of Interturn Short Circuit Fault Based on Axial Split Phase Permanent Magnet Synchronous Machine

In order to solve the problem that three-phase PMSM cannot operate under interturn short circuit (ITSC) fault, an ITSC fault mitigation scheme based on three-phase axial split phase permanent magnet synchronous machine (ASP-PMSM) is proposed in this paper. The ASP-PMSM has inherently superior fault isolation capability among phases, high inductance and low copper loss induced by ITSC current, which greatly reduces the fault severity and difficulty of fault mitigation from machine structure. The inherently low fault severity of ASP-PMSM leaves space for postfault torque production. Therefore, it does not need the phase current to be totally injected to d-axis. As a result, the operation of three-phase PMSM under ideal ITSC fault can be realized while maintaining more than half of rated torque. In order to find out the most serious fault condition for different winding types, the influence of the number of parallel strands and the SC turn ratio on the severity of ITSC fault is investigated by theoretical analysis (TA) and finite element analysis (FEA) for the first time. And the effectiveness of the fault mitigation for the ASP-PMSM with different number of parallel strands is investigated by FEA. Finally, a three-phase prototype of ASP-PMSM is served as an example to verify the validity of analysis above. The ITSC current and temperature at different SC turn ratio and operating conditions are tested. The test results are consistent with that of TA and FEA. It is verified that the proposed fault mitigation scheme can realize the postfault operation of three-phase PMSM.

Multi-material topology optimization using Wachspress interpolations for designing a 3-phase electrical machine stator

This work uses multi-material topology optimization (MMTO) to maximize the average torque of a 3-phase permanent magnet synchronous machine (PMSM). Eight materials are considered in the stator: air, soft magnetic steel, three electric phases, and their three returns. To address the challenge of designing a 3-phase PMSM stator, a generalized density-based framework is used. The proposed methodology places the prescribed material candidates on the vertices of a convex polytope, interpolates material properties using Wachspress shape functions, and defines Cartesian coordinates inside polytopes as design variables. A rational function is used as penalization to ensure convergence towards meaningful structures, without the use of a filtering process. The influences of different polytopes and penalization parameters are investigated. The results indicate that a hexagonal-based diamond polytope is a better choice than the classical orthogonal domains for this MMTO problem. In addition, the proposed methodology yields high-performance designs for 3-phase PMSM stators by implementing a continuation method on the electric load angle.

Multiple Synchronous Reference Frame Current Harmonic Regulation of Dual Three Phase PMSM With Enhanced Dynamic Performance and System Stability

This article proposes an improved multiple synchronous reference frame (MSRF) current harmonic regulation strategy for dual three phase permanent magnet synchronous machine drive system. A new vector space decomposition transformation combined with auxiliary currents is designed to decouple the current fundamental with current harmonics, and the auxiliary currents can be established by the π/9 phase shifting of the physical currents in <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">ABC</i> set and the π/18 phase shifting of the physical currents in <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">XYZ</i> set. By employing the proposed current decomposition, it is easy to detect them using low pass filters in MSRFs. A generic complex vector proportional integral regulator is then employed to control the detected current harmonics to track the current harmonic references. Compared with the existing MSRF-based methods, the proposed method provides a new current harmonic detection with reduced delay effect, which contributes to enhancing the dynamic performance of current harmonic regulation, and also stabilizing the control system. Comprehensive experimental results are given to validate the effectiveness of the proposed control strategy.

Multi‐material topology optimization of a rotating electrical machine with a density‐based method

AbstractTopology optimization (TO) has been extensively studied in the past decades especially in mechanical engineering. Among different techniques, density‐based methods have become very popular. In electrical engineering, TO has been applied essentially to linear actuators [1] or machines rotors [2] [3], but few works such as [4] deal with the coil repartition within the stator of rotating machines.In this study, we investigate a density‐based topology optimization method, which aims to maximize the average torque of a rotating electrical machine from random or uniform initial material repartition. Material properties such as magnetic permeability or current density are interpolated on densities between each material to obtain a differentiable optimization problem, using SIMP or RAMP [5] for example. A custom magnetostatic finite element solver was implemented on MATLAB®. It takes into account the non‐linearity of magnetic materials with Newton‐Raphson method. The optimization algorithm relies on sensitivities obtained by the adjoint variable method (AVM) [6]. The methodology was performed for two test cases :• optimization of iron/air repartition within the rotor of a synchronous reluctant machine (SRM)• optimization of coils/iron/air repartition within the stator of a one phase permanent magnet synchronous machine (PMSM).In the air/iron case, a filtering technique inspired by ESO [7] is applied: iron which carries few magnetic flux is removed. No filtering was applied in the multi‐material case, but a normalization of the gradient was investigated.As a result, we obtain flux barriers [8] for the optimized SRM rotor, which correspond to industrial designs. However, some convergence issues happened, especially for multi‐material optimization. The gradient normalization helps preventing this phenomenom but leads to surprising asymmetric designs, which need further investigations. It is also necessary to improve the robustness of the method especially for high current density, in order to optimize both the rotor and the stator. Multiphysics considerations will be taken into account in future work.

Compensation of Selective Current Harmonics for Switching-Table-Based Direct Torque Control of Dual Three-Phase PMSM Drives

Current harmonics are ubiquitous in dual three phase (DTP) permanent magnet synchronous machine (PMSM) drives. Due to back electromotive force (EMF) distortion, significant current harmonics are generated in the DTP-PMSM system. The influence of back EMF harmonics is investigated in this paper and a novel switching-table-based direct torque control method to compensate the selected current harmonics caused by the back EMF harmonics is proposed. It shows that by employing different optimal action time durations for voltage vectors in the z <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">1</sub> z <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> subspace and setting the synthetic voltage vectors to non-zero, the stator flux harmonics caused by the back EMF harmonics can be selectively compensated, as verified by experiments.

A Simple Sensorless Position Error Correction Method for Dual Three-Phase Permanent Magnet Synchronous Machines

In this article, a simple position error correction method is proposed to minimize the influence of parameter deviation on the model-based rotor position estimation, with the help of two sets of windings in a dual 3-phase permanent magnet synchronous machine (PMSM). In the proposed method, when each set of 3-phase windings is individually used for sensorless rotor position estimation, the nominal parameters that are set in each observer are identical but inaccurate, which leads to errors in the estimated rotor position from both observers. Since the error is varied according to the current level, small current pulses are injected respectively into <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">d</i> - or <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">q</i> -axis of one set (or both set) of 3-phase windings, which causes the difference between the rotor position estimation errors from two sets of 3-phase windings. This difference is subsequently used as the input of an updated controller to minimize the parameter deviation and the corresponding rotor position error. The proposed method is experimentally validated on a dual 3-phase PMSM system.

Advanced Design Optimization Technique for Torque Profile Improvement in Six-Phase PMSM Using Supervised Machine Learning for Direct-Drive EV

Few of the challenges with development of a single on–board motor for direct–drive electric vehicles include high torque density and low torque ripple. Therefore, in this paper, a 36–slot, 34–pole consequent pole six–phase permanent magnet synchronous machine (PMSM) has been optimized to address the aforementioned challenges for direct–drive application. Existing literature on optimization processes that rely solely on finite element models are restricted to three–phase machines only and also take longer computation time. Therefore, this paper proposes a novel optimization approach based on supervised machine learning for six–phase PMSM. In this approach, a non–conventional extended dual dq– frame model that accounts for higher order space harmonics in inductances and flux linkages has been developed and used for accurate computation of average torque and torque ripple of six–phase PMSM. Using the performance characteristics obtained from the extended dual dq –frame model for a set of initial design candidates, support vector regression algorithm is employed for supervised machine learning and increasing solutions in the design space. Furthermore, pareto front is used for selecting optimal machine models with maximum torque density and reduced torque ripple. Multi–objective trade–offs and comparison of initial and optimized designs based on average torque, torque ripple, efficiency and cost are performed.

Detecting of Multi Phase Inter Turn Short Circuit in the Five Permanent Magnet Synchronous Motor

Abstract This paper proposes a general model of five phase permanent magnet synchronous machine (PMSM) which is capable of representing the multiphase Inter Turn Short Circuit (ITSC) occurring in several phase simultaneously this model is based on a coupled magnetic circuit approach leading to a differential equations system goveming the induction machine behavior. The obtained time-differential state equations system is implemented under Matlab environment and numerically solved using the fourth order Rung-Kutta method with variable step time corrected at each rotor displacement through the electromagnetic torque. Also, Fast Fourier Transform and (FFT) analysis is performed to the phase current signal to detect the frequency spectrum, Power Spectral Density (PSD) is chosen as a classification method. Its efficiency depends on its ability to discriminate between various faults generating the same range of harmonics in the stator current spectrum and on its ability to evaluate the fault severity. So, in order to improve the efficiency of these diagnosis methods, one needs a relatively accurate model to simulate the five-phase PMSM in the case of inter-tum short circuit fault helping to predict performances andor to extract fault signature in the machine main quantities. Simulation work has been carried out using MATLAB to verify the performance of the proposed detection/diagnosis method.

Five-Phase Permanent Magnetic Synchronous Motor Fed by Fault Tolerant Five Phase Voltage Source Inverter

&lt;p&gt;Multiphase machines have gained attention in numerous fields of pplications such as Aircraft, ship propulsion, petrochemical and automobiles, where high reliability is required. The additional number of phases guarantees that the system continues to operate in faulty conditions compared to the traditional three-phase machine due to the high degree of freedom. Among faults able to affect multiphase system, break between a machine phase and the voltage source inverter (VSI) degrade the performance of the control. In this paper, a five-phase permanent magnet synchronous machine (PMSM) is fed through a fault tolerant voltage source inverter with new structure to ensure drive continuity when open circuit occurs. The five phase PMSM is controlled with fuzzy logic regulator to minimize disturbance impact that can arise fault condition. Paper is accomplished with real time simulations using MATLAB-Simulink in order to validate the new topology and show the effectiveness of the proposed solution.&lt;/p&gt;

Enhancement of Steady-State Performance in Direct Torque Controlled Dual-three Phase Permanent Magnet Synchronous Machine Drives with Modified Switching Table

This paper investigates the improved switching-table-based direct torque control strategies (ST-DTC) for dual three-phase permanent magnet synchronous machine drives. The classical ST-DTC scheme for dual three-phase drives is usually seriously penalized by significant current harmonics, which cause large losses and reduce the efficiency of the drive system. Hence, a modified switching table consisting of 12 new synthetic voltage vectors is proposed. With this new switching table, not only the variables relating to the torque production are well controlled, but also the variables contributing to the current harmonics are eliminated successfully within one sampling period. Furthermore, a simple modified torque regulator is proposed to reduce the torque ripple and the steady-state error of torque which is usually observed in the real-time system. The switching sequence which is most suitable for the implementation of the real-time system has been proposed to minimize the computation burden. The proposed strategy only changes the switching table and torque regulator without any major modifications, and hence, the merits of the classical direct torque control, i.e., simple structure and good robustness, are still preserved. The experimental results validate the effectiveness of the proposed strategy.

Coupled Field-Circuit Estimation of Operational Inductance in PM Synchronous Machines by a Real-Time Physics-Based Inductance Observer

This paper presents a new real-time inductance estimation method for 3-phase permanent magnet synchronous machine (PMSM), utilizing a physics-based inductance observer. The mathematical modeling, stability analysis, and transient analysis of the observer are developed and described in details. The inductance of a 3-phase, 250 W, radial flux PMSM was calculated by an electromagnetic field-circuit based finite-element analysis with motion. The numerical results are compared with the experimental results obtained from the developed inductance observer. The results show excellent agreement in steady state operating conditions.

A Complete Optimal Control Solution for Permanent Magnet Synchronous Motors

In this paper a voltage control strategy based on the optimal control theory, for isotropic rotor permanent magnet synchronous motor (PMSM) drives, is proposed. The complete optimal control of the three phase permanent magnet synchronous machine (PMSM) consists of three components: the state feedback, the feed forward compensation of the load torque and the reference to achieve the desired state. The control assures a smooth dynamic response, in order to achieve the desired state in steady state, the fast compensation of the load torque, and the energy minimization. The obtained solution by integrating the matrix Riccati differential equation (MRDE) is orientated towards the numerical implementation (by using a zero order hold) and it is computed on-line. The optimal control strategy is applied to PMSM drives and verified by simulations.

Vss Speed Sensorless Control of PMSM

The speed sensorless control of nonsalient PMSM that uses estimated rotor flux instead of the transformation angle is designed. This paper introduces a new sequential switching control strategy for a current control of a three phase inverter. The key idea is to integrate the benefits of the variable structure system control design and the event-driven sequential control structures to raise the system performance and control efficiency. The design is applied to the control of three phase permanent magnet synchronous machine. The operation at low speed is improved by reducing the disturbance impact. The estimation angle error at zero speed is limited by injecting the DC current that compensates the unknown load torque and enables operation at zero speed. The VSS speed sensorless control of PMSM is implemented on a DSP/FPGA system, and verified experimentally.