Six-phase Permanent Magnet Synchronous Motor Research Articles

A Review on the Fault-Tolerant Method of PMSM using Finite Element Method by Modifying Phase Angle for EV Applications

Abstract: The present research reviews a fault-tolerant technique for Permanent Magnet Synchronous Motors (PMSMs) that involves phase angle adjustment. Fault tolerance standards for the motor used in electric vehicles are necessary due to the rapid development of these vehicles. The primary option for electric vehicle drive motors is increasingly being replaced with permanent magnet synchronous motors (PMSM), which have minimal torque ripple, great durability, and other benefits. After comparing a six-phase PMSM to a conventional three-phase PMSM, the performance following a phase open is examined. A fault-tolerant technique for modifying the left phase current's phase angle to reduce torque ripple following a phase open is then described. The finite element simulation indicates that the six-phase PMSM's output torque ripple is reduced, and the fault-tolerant technique that is being described can further reduce the torque ripple.

A New Traction System With Asymmetrical Six-Phase Permanent Magnet Synchronous Motors for Hydrogen Trains

A New Traction System With Asymmetrical Six-Phase Permanent Magnet Synchronous Motors for Hydrogen Trains

On winding reconstruction method for six-phase motor with single-phase winding open-circuit faults

Single-phase winding fault in six-phase permanent magnet synchronous motor (PMSM) will cause problems with reduced torque performance. For this problem, this paper analyses the reasons for the increase of torque ripple under single-phase winding open-circuit fault condition taking an 18-slot/10-pole (18S10P) six-phase surface mounted permanent magnet synchronous motor (SPMSM) as an example. Then, a torque performance improvement method by redistributing healthy phase windings to reconstruct the stator magnetic field is proposed in this paper. The proposed method not only can significantly reduce torque ripple caused by winding open-circuit faults but also can maintain a high average torque value. Moreover, this method is suitable for lots of six-phase motors with different pole-slot combinations. At last, considering the significant impact of harmonic contents in stator magnetic field on torque performance, an optimization method for armature current is proposed, which can decrease the torque ripple further. The simulation results by finite element analysis (FEA) show that the proposed method has significant superiority in motor fault operation.

Backstepping speed controller design for a multi-phase permanent magnet synchronous motor drive

This paper deals with the synthesis of a speed control strategy for a six-phase permanent magnet synchronous motor (PMSM) drive based on backstepping controller (BC). The Backstepping control is a systematic and recursive design methodology for nonlinear feedback control. The results demonstrate that backstepping controller has the advantage of rapid response, no overshoot and stability compared with PI controller.

Cascaded Model Predictive Control of Six-Phase Permanent Magnet Synchronous Motor with Fault Tolerant Ability

Cascaded Model Predictive Control of Six-Phase Permanent Magnet Synchronous Motor with Fault Tolerant Ability

Fault-tolerant control strategy of six-phase permanent magnet synchronous motor based on deadbeat current prediction.

The fault-tolerant control after phase loss is crucial in the studies of the six-phase permanent magnet synchronous motor (PMSM), and the one phase loss is the most frequent phase loss fault. To improve the system instability caused by nonlinear and time-varying perturbations of inductance parameters in a double-Y phase shifted 30° six-phase PMSM, an improved deadbeat predictive current fault-tolerant control (DPC-FTC) method is proposed in this study. The transformation matrix after single-phase open-phase is first reduced and reconstructed, and the reduced-dimensional voltage equation is derived. Based on this equation, the deadbeat current predictive control is then used to predict the expected voltage using the current feedback value and the reference value, so as to shorten the response time and improve the overall control effect. The voltage equation after parameter perturbation is rewritten, and the current discrete transfer function under constant expected voltage before and after parameter perturbation is calculated. Afterwards, to further improve the low stability of fault-tolerant control after phase loss, which is caused by the inductance parameter perturbation of the control system, the weight coefficient is introduced in order to enhance the deadbeat predictive current control so that it splits and optimizes the direct-quadrature axis current. The stability of the system is then analyzed. By changing the weight coefficient, the fault-tolerant control system has a wider stable working range. Finally, the simulation model and experimental platform are completed. The results show that the improved DPC-FTC method improves the permissible inductor parameter uptake range by a factor of 1/β, reduces the current static difference by 32.05% and 46.02% when the inductor parameter is mismatched by a factor of 2, reduces the current oscillation and effectively reduces the sensitivity of system stability to inductor parameter uptake.

Temperature Analysis for the Asymmetric Six-Phase Permanent Magnet Synchronous Motor in Healthy and Fault-Tolerant Modes

The asymmetric six-phase permanent magnet synchronous motor (AS-PMSM) can switch to five- or three-phase operation in the case of winding and drive leg fault. This paper analyses the temperature distribution of the AS-PMSM with different fault-tolerant modes and provides theoretical support to improve the reliability of the machine and its drive system. A 22-pole 24-slot AS-PMSM with physical, magnetic, and thermal isolation is designed first. Then, the systematic analysis method, considering the inverter, the machine and the control algorithm, is proposed. The magnetic field and losses of the AS-PMSM are addressed in multiple modes, including the six-phase, the five-phase (minimum loss / maximum torque) and the three-phase operation. Furthermore, a three-dimensional model, bi-directionally coupling electromagnetic field and temperature, is established based on the theory of transient temperature field and fluid dynamics. The model reveals the temperature propagation law and the temperature variation of the AS-PMSM in four modes. The proposed theoretical analysis is finally proved effective by experiments.

A Novel Modulation Strategy for Asymmetrical Six-Phase Series-Winding PMSM Based on Predictive Controller

Series-winding (SW) permanent magnet synchronous motors (PMSMs) are of increasing interest and great potential for low-voltage traction in electric vehicles because of their both higher DC voltage utilization and fewer inverter legs. A few studies attempt to promote this topology from three-phase to multi-phase frame. However, the SW topology for asymmetrical multi-phase system has yet to be understood, given the fact that all existing voltage modulation strategies are not applicable. The study presents a feasible, simple carrier-based modulation strategy for this special SW-PMSM with an asymmetrical winding system. A predictive current controller is introduced in the process of modulation since the multi-phase system involves several current control loops. An asymmetrical six-phase PMSM prototype is fabricated for verification. Experimental results show that the novel strategy performs much better than its space-vector-based counterparts. Also, it is capable of suppressing the current distortion within the nonlinear modulation range. Voltage utilization and achievable rotational speed become higher.

Robust synergetic control of electric vehicle equipped with an improved load torque observer

Abstract For environmental reasons, a great effort was focused on the improvement of the steady-state performance and dynamic performance of electric vehicles (EV). The EV is one of the cleanest and most ecological transport solutions. Accurate knowledge of EV load torque signals is important information for controlling and improving EV active safety. The estimation of load torque in EV drive contributes to cost reduction and solves many of the implementation problems encountered: lack of space, and severe environment. On this basis, in this research, our contribution contains two parts. The first part is the conception of a new scheme of control based on synergetic control (SC) for the speed of an EV propelled by a Six-Phase Permanent Magnet Synchronous Motor (PMSMs) is developed. This control technique offers a fast response, decreases the size of modeled system, and asymptotic stability of the closed-loop system in a vast domain. The second part deals with the synthesis of the sliding mode observer (SMO) to estimate load torque, compensate for strong disturbances and achieve high servo precisions. Moreover, reducing the chattering is inherent in the conventional SMO, we have proposed to replace the switching observer term Ksign with a smooth function and super twisting algorithm. The obtained simulation results proved the high performance assured by the synergetic control such as robustness and dynamic performance, and good estimation accuracy with free chattering even in strong noises.

Predictive Current Control for Six-Phase PMSM Motor With Multi-Step Synthesis Based Virtual Vectors

The concept of virtual vector has been a standard practice for the multiphase machine drives. However, simply adopting the fixed or adjustable duty-ratio virtual vectors fails to mitigate the current tracking error in the fundamental plane satisfactorily. To that end, this paper proposes a new model predictive control (MPC) method for a six-phase permanent magnet synchronous motor (PMSM) using multi-step synthesis based virtual vectors to regulate two planes simultaneously. The virtual vectors are formed through a two-step synthesis process. First, two groups of real vectors are used to synthesize 12 elementary virtual vectors to nullify the harmonic currents in the secondary plane. Subsequently, the 12 elementary virtual vectors are employed to further form other 60 composite virtual vectors to enhance the current tracking in the fundamental plane. For the sake of easy practical implementation, the pulse width modulation (PWM) switching sequence of all virtual vectors are analyzed to ensure that they present standard PWM switching sequence. The proposed multi-step synthesized composite virtual vectors can suppress the harmonic currents in the secondary plane and reduce the current tracking error in the primary plane simultaneously. Experimentations are conducted to verify the effectiveness of the proposed method.

Open-Circuit Fault-Tolerant Control of a Six-Phase Asymmetric Permanent Magnet Synchronous Motor Drive System

One innovative composite fault-tolerant control tactic is presented for the reliable operation of a power transmission system, which consists of both an asymmetric six-phase permanent magnet synchronous motor (PMSM) and a T-type mid-point clamp type (T-NPC) three-level inverter. First, in order to inherit the better harmonic property of simplified space vector modulation (SVM) and the rapid dynamic capability of direct torque control (DTC), the SVM-DTC control scheme was determined, and the harmonic electric current suppression unit was added to the basic control scheme to obtain good harmonic electric current suppression. In addition, a strategy for open-circuit fault-tolerant control under the SVM-DTC scheme was designed by analyzing the mutual influence between the stator flux linkage and the stator voltage of each phase under an open-circuit fault. Finally, the PMSM drive system principle prototype was tested. By comparing the waveforms of output torque and current of each phase before and after fault tolerance, it shows that the large torque fluctuation (±5%) before fault tolerance was suppressed to ±2% and smoothed out, verifying the effectiveness of fault tolerance control.

Control strategy of MW flywheel energy storage system based on a six-phase permanent magnet synchronous motor

The implementation of the “dual carbon” goal, nationally in China, has accelerated the profound transformation of the energy industry, and the development and utilization of large-scale clean energy has become a basic global consensus. However, clean energy is having trouble meeting the needs of rigid energy demands due to its randomness, intermittency, and unpredictability, so energy storage is currently being considered to solve this incompatibility. The flywheel energy storage system (FESS) cooperates with clean energy power generation to form “new energy + energy storage”, which will occupy an important position among new energy storage methods. This study analyzes the basic requirements of wind power frequency modulation, establishes the basic model of the flywheel energy storage system, adopts a six-phase permanent magnet synchronous motor as the system driver, designs an eleven-stage pulse width modulation control method, and proposes a power and current double-closed loop. The control strategy is used to test and simulate the machine-side converter that has been built. The results show that the proposed control strategy is reasonable and effective. By introducing a six-phase permanent magnet synchronous motor into FESS, the system could output higher power under the condition of low voltage and the noise and vibration of the motor are optimized during operation. Most importantly, the stability of the FESS is guaranteed in actual operation.

Improved Multi-Stage Decoupling Space Vector Modulation for Asymmetrical Multi-Phase PMSM With Series Winding Connection

This article is devoted to developing a unique series-winding drive (SWD) topology, analyzing and implementing its control schemes for asymmetrical multiphase permanent magnet synchronous motor (PMSM). Proposed SWDs have higher voltage utilization than ordinary wye or delta connection, but vary with the number of inverter legs and connection sequence. Also, they have a simpler topology, fewer inverter legs, and power modules than the open-end winding drives. The article selects the typical asymmetrical six-phase (ASP) PMSM as the target. The complex space vector mapping is screened and simplified by unified hexadecimal coding for both eight-leg and seven-leg drives. Given the multiple suspaces in ASP-PMSM, a multistage decoupling space vector modulation scheme is proposed and improved for SWDs. It incorporates the processes of vector synthetization, cost function minimization, and zero-sequence compensation. Prototype fabrication and control experiments are carried out. Results show that the proposed MSD SVM is applicable to all connection sequences. It can suppress the harmonic current to a quite low level, in both steady-state and dynamic states. Also, this article discusses the current burden of the inverter and provides suggestions.

Fault‐tolerant control technology of symmetrical six‐phase permanent magnet synchronous motor

In comparison with three-phase motors, multiphase motors have garnered increasing attention owing to their high fault-tolerant ability. When the motor has an open-circuit fault, the stator combined magnetomotive force (MMF) changes, αβ and z1z2 subspaces are no longer decoupled, and the conventional vector control causes phase current distortion, harmonic current increase, and torque fluctuation of the motor. To address the aforementioned problems, first, the mathematical model of the common neutral symmetric six-phase permanent magnet synchronous motor in the static coordinate system is presented in this paper. Second, the transformation matrix of αβ and z1z2 subspace decoupling is proposed, and the corresponding mathematical model of decreasing order is constructed. Third, considering the orthogonal vector of the remaining dimension after the phase fault, the reduced-order transformation matrix expression of the general single-phase fault is obtained, which is further extended to the double-phase fault. Fourth, the harmonic current of the z1z2 subspace was tracked and controlled by the proportional integral resonant (PIR) regulator. Finally, simulation and experimental verification are performed, and the results demonstrate that the fault-tolerant control algorithm proposed in this paper can effectively reduce the torque ripple and it has good dynamic performance after an open-circuit fault.

A New Synergetic Scheme Control of Electric Vehicle Propelled by Six-phase Permanent Magnet Synchronous Motor

Electric Vehicles (EVs) are a promising alternative to conventional vehicles powered by internal combustion motors, of fering the possibility of reducing CO2, pollutants, and noise emissions. As known, the control of such an electric vehicle takes into account several phenomena governing its behavior, which is a complicated problem because of the non-linearities, unmeasured disturbance, and parameters uncertainty of this system. This problem is one of the important challenges facing controller designers. Various control techniques have been proposed to enhance EV’s performance. On this basis, in this research, a new synergetic scheme of electric vehicles propelled by Six-Phase Permanent Magnet Synchronous Motor (PMSMs) is developed. The synthesis of the proposed Synergetic Controller (SC) is based on the selection of four-manifolds of stator current of PMSMs. The SC provides fast response, asymptotic stability of the closed-loop system in wide range operating condition, and decrease the size of modeled system. Also, the principal feature of SC is that it supports parameters variation. Furthermore, to illustrate the improvements and the performances of the proposed controller, a comparison study between various nonlinear controllers such as Integral Action in Sliding Mode (ISMC), Super Twisting Sliding Mode (STSM), using a dynamic model of the lightweight vehicle under New European Driving Cycle (NEDC) was done. The obtained simulation results under several operating conditions show the efficiency and superiority of the proposed control compared with nonlinear controllers; also, it demonstrates the feasibility of the proposed control approach for real systems.

Fault-Tolerant Operation of a Six-Phase Permanent Magnet Synchronous Hub Motor Based on Model Predictive Current Control With Virtual Voltage Vectors

This paper proposes a model predictive current control (MPCC) compensation method based on virtual voltage vectors for single-phase open-circuit faults of an asymmetric six-phase permanent magnet synchronous hub motor (PMHSM). The proposed strategy adopts the normal vector space to decompose the transformation matrix without reconfiguring the controller topology. By analyzing the difference between the open-circuit phase voltage and the state of health, the disturbance term of the prediction vector in the α-β and x-y subspaces is obtained. 64 voltage vectors are obtained from the switching states of the 6-phase two-level inverter, and then these 64 voltage vectors are appropriately compensated and synthesized into 24 new virtual voltage vectors. The new virtual vectors avoid the adjustment of the MPCC weighting factors and the synthesized virtual vectors can suppress current harmonics. Finally, the experimental results show the effective performance of the method before and after the fault-tolerant operation.

Model predictive flux control of six-phase permanent magnet synchronous motor with novel virtual voltage vectors

Model predictive flux control of six-phase permanent magnet synchronous motor with novel virtual voltage vectors

Control Strategy of Mw Flywheel Energy Storage System Based on a Six-Phase Permanent Magnet Synchronous Motor

Control Strategy of Mw Flywheel Energy Storage System Based on a Six-Phase Permanent Magnet Synchronous Motor

Fault-tolerant model predictive control of six-phase permanent magnet synchronous hub motors

Permanent magnet synchronous hub motors (PMSHMs) have been gradually introduced into the applications of electric vehicles. On this basis, the six-phase motor has the characteristics of high reliability, high power density and low torque ripple. And its fault tolerance is a large advantage compared with the three-phase motor. The multi-phase permanent magnet synchronous motor is redundant due to the number of phases. When the motor fails, it does not have to stop running, merely adjust its control mode and enter the fault-tolerant compensation control algorithm to resume the operation of the system. The FCS-MPC algorithm can replace the cascade structure in the traditional control and eliminate the modulation module. This makes it have good steady-state performance. The speed response is also improved. It can be combined with multiple control objectives with strong flexibility by simply changing the objective function. The prediction model is compensated. Finally, the experimental results show the effectiveness of this method.

A novel high torque density six‐phase axial‐flux permanent magnet synchronous motor with 60° phase‐belt toroidal winding configuration

The three-phase permanent magnet synchronous motor (three-phase PMSM) has gained much popularity in many applications due to its various advantages. In addition, due to the good fault tolerance, simple inverter circuit structure and high torque density, the six-phase PMSM has better prospects than three-phase PMSM in biomedical devices, electric vehicles and other fields with high reliability requirements. In this study, a six-phase axial-flux PMSM inherently without cogging torque is proposed to improve torque density, which equips the 60° phase-belt toroidal winding (60°TW) and slotless stator core. Based on the same effective volume, permanent magnet material, power grade and the other major motor parameters, two six-phase PMSMs with 30° phase-belt toroidal winding (30°TW) and 60°TW are designed, respectively. The armature reaction field, air gap magnetic density, back-electromotive force, output torque, loss characteristic and torque-speed characteristic are compared by using three-dimensional (3D) finite-element models in detail. Finally, the experimental test is carried out using the prototype of three-phase PMSM with 120° phase-belt toroidal winding. The experimental results indirectly verify the feasibility of 60° phase-belt toroidal winding and correctness of 3D FEM. The 3D FEM analysis results are presented to show that torque density of the proposed six-phase PMSM with 60°TW is improved in comparison to the six-phase PMSM with 30°TW. Index Terms—60° phase-belt toroidal winding, axial flux, six-phase permanent magnet synchronous motor, torque density