Five-phase Synchronous Reluctance Machines Equipped with a Novel Type of Fractional Slot Winding

Multi-phase machines are so attractive for electrical machine designers because of their valuable advantages such as high reliability and fault tolerant ability.Meanwhile,fractional slot concentrated windings(FSCW)are well known because of short end winding length,simple structure,field weakening sufficiency,fault tolerant capability and higher slot fill factor.The five-phase machines equipped with FSCW,are very good candidates for the purpose of designing motors for high reliable applications,like electric cars,major transporting buses,high speed trains and massive trucks.But,in comparison to the general distributed windings,the FSCWs contain high magnetomotive force(MMF)space harmonic contents,which cause unwanted effects on the machine ability,such as localized iron saturation and core losses.This manuscript introduces several new five-phase fractional slot winding layouts,by the means of slot shifting concept in order to design the new types of synchronous reluctance motors(SynRels).In order to examine the proposed winding’s performances,three sample machines are designed as case studies,and analytical study and finite element analysis(FEA)is used for validation.

Encoderless Five-phase PMa-SynRM Drive System Based on Robust Torque-speed Estimator with Super-twisting Sliding Mode Control

In this paper,a robust torque speed estimator(RTSE)for linear parameter changing(LPC)system is proposed and designed for an encoderless five-phase permanent magnet assisted synchronous reluctance motor(5-phase PMa-SynRM).This estimator is utilized for estimating the rotor speed and the load torque as well as can solve the speed sensor fault problem,as the feedback speed information is obtained directly from the virtual sensor.In addition,this technique is able to enhance the 5-phase PMa-SynRM performance by estimating the load torque for the real time compensation.The stability analysis of the proposed estimator is performed via Schur complement along with Lyapunov analysis.Furthermore,for improving the 5-phase PMa-SynRM performance,five super-twisting sliding mode controllers(ST-SMCs)are employed with providing a robust response without the impacts of high chattering problem.A super-twisting sliding mode speed controller(ST-SMSC)is employed for controlling the PMa-SynRM rotor speed,and four super-twisting sliding mode current controllers(ST-SMCCs)are employed for controlling the 5-phase PMa-SynRM currents.The stability analysis and the experimental results indicate the effectiveness along with feasibility of the proposed RTSE and the ST-SMSC with ST-SMCCs approach for a 750-W 5-phase PMa-SynRM under load disturbance,parameters variations,single open-phase fault,and adjacent two-phase open circuit fault conditions.

Performance Analysis and Comparison of Two Fault-Tolerant Model Predictive Control Methods for Five-Phase PMSM Drives

Model predictive current control(MPCC)and model predictive torque control(MPTC)are two derivatives of model predictive control.These two control methods have demonstrated their strengths in the fault-tolerant control of multiphase motor drives.To explore the inherent link,the pros and cons of two strategies,the performance analysis and comparative investigation of MPCC and MPTC are conducted through a five-phase permanent magnet synchronous motor with open-phase fault.In MPCC,the currents of fundamental and harmonic subspaces are simultaneously employed and constrained for a combined regulation of the open-circuit fault drive.In MPTC,apart from the torque and the stator flux related to fundamental subspace,the x-y currents are also considered and predicted to achieve the control of harmonic subspace.The principles of two methods are demonstrated in detail and the link is explored in terms of the cost function.Besides,the performance by two methods is experimentally assessed in terms of steady-state,transition,and dynamic tests.Finally,the advantages and disadvantages of each method are concluded.

Fault-Tolerant Operation of Five-Phase Permanent Magnet Synchronous Motor with Independent Phase Driving Control

The multi-phase motor drive system with multiple H-bridge power supply has high fault tolerance,which is widely used in aerospace,electric vehicle,ship integrated power system and other fields.In this paper,a fault-tolerant control strategy based on decoupling control and stator current compensation is proposed for the propulsion system of five-phase PMSM with independent neutrals.Firstly,the mathematical model of PMSM is established by using vector space decoupling method;Secondly,a stator current compensation method is adopted to carry out fault-tolerant control after the motor has single-phase and two-phase open-circuit faults and the fault-tolerant control system based on decoupling control is established;Finally,the decoupling control model and the fault-tolerant control of stator current compensation are verified by the simulation and experiment.The simulation and experiment results show that the method can reduce the torque ripple caused by the stator winding open-circuit fault,and the operation performance of the motor under fault condition is significantly improved.

Speed sensorless FCS-MPTC based on FOSM-MRAS five-phase permanent magnet synchronous motor

For the two-level five-phase permanent magnet synchronous motor(FP-PMSM)drive system,an improved finite-control-set model predictive torque control(MPTC)strategy is adopted to reduce torque ripple and improve the control performance of the system.The mathematical model of model reference adaptive system(MRAS)of FP-PMSM is derived and a method based on fractional order sliding mode(FOSM)is proposed to construct the model reference adaptive system(FOSMMRAS)to improve the motor speed estimation accuracy and eliminate the sliding mode integral saturation effect.The simulation results show that the FP-PMSM speed sensorless FCS-MPTC system based on FOSM-MRAS has strong robustness,good dynamic performance and static performance,and high reliability.

Comparative Study on Torque Performance of Five-phase Single-Stator and Double-Stator Permanent Magnet Synchronous Motors

This paper compares the torque characteristics of single stator permanent magnet synchronous motor(PMSM)and double-stator PMSM under different split-ratios,air-gap lengths and shaft diameters by finite element method.Firstly,the effects of split-ratio towards the torque characteristics of the two motor structures under different air-gap lengths are researched,the results show that the optimal split-ratios of the two motor structures do not change under different air-gap lengths,and the optimal split-ratio of the double-stator motor is greater than that of single-stator,and the torque of the double-stator motor is greater than that of single-stator motor with arbitrary split-ratio under the same air-gap length;Finally,the effects of the shaft diameter to the torque of the two motor structures are investigated,obtaining that with the increasing of shaft diameter,the electromagnetic torque of the single-stator motor is almost unchanged,however,the torque of the double-stator is gradually reduced,when the shaft diameter reached a certain extent,the electromagnetic torque of the double-stator motor is smaller than that of single-stator motor with the split ratio within a certain range,and the torque/quality ratio of the double-stator motor is smaller than that of single-stator motor with their optimal split ratio separately.

Analysis of Direct Torque Control for Marine Five-Phase Induction Motor

Based on the principle of direct torque control,a DTC(Direct Torque Control)system with five-phase induction motor has been studied.Providing direct control of stator flux and electromagnetic torque by optimized voltage vector,five-phase induction motor enhances flexibility of the invert states selection by increasing the number of voltage vectors,resulting in more precise control of stator flux and electromagnetic torque.The model of DTC for five-phase induction motor is constructed on equations and the method of approximate circle of torque track is used to conduct the simulation analysis of the system.The simulation results demonstrate that the DTC for five-phase induction motor control has merits of little calculation compared with vector control,simple structure,fast response and greater dynamic performance.

Exponential response electrical pole-changing method for a five-phase induction machine with a current sliding mode control strategy

Electrical pole-changing technology leads to torque ripple and speed fluctuation despite broadening the constant power speed range of the multiphase induction machine （IM） system. To reduce the torque ripple and speed fluctuation of the machine, we investigate an exponential response electrical pole-changing method for five-phase IM with a current sliding-mode control strategy. This control strategy employs the dual-plane （dr-q1 and d2-q2） vector control method, which allows the IM to operate under different pole modes. Current sliding-mode controllers are applied instead of conventional proportional integral （PI） controllers to adjust the current vectors, and exponential current response achieves a smooth transition between the d1-q1 and d2-q2 planes. Compared with the step response pole-changing with PI control method, the proposed pole-changing method greatly reduces the torque ripple and speed fluctuation of the IM during the pole-changing process. Experimental results verify the ex- ceptional performance of the proposed electrical pole-changing strategy.

Fault-tolerant Deadbeat Model Predictive Current Control for a Five-phase PMSM with Improved SVPWM

The main drawbacks of traditional finite set model predictive control are high computational load,large torque ripple,and variable switching frequency.A less complex deadbeat(DB)model predictive current control(MPCC)with improved space vector pulse-width modulation(SVPWM)under a single-phase open-circuit fault is proposed.The proposed method predicts the reference voltage vector in the a-β subspace by employing the deadbeat control principle on the machine predictive model;thus,the exhaustive exploration procedure is avoided to relieve the computational load.To perform the constant switching frequency operation and achieve better steady-state performance,a modified SVPWM strategy is developed with the same conventional structure,which modulates the reference voltage vector.This new approach is based on a redesigned and adjusted post-fault virtual voltage vector space distribution that eliminates the y-axis harmonic components in the x-y subspace and ensures the generation of symmetrical PWM pulses.Meanwhile,the combined merits of the DB,MPCC,and SVPWM methods are realized.To verify the effectiveness of the proposed control scheme,comparative experiments are performed on a five-phase permanent magnet synchronous motor(PMSM)drive system.

Field-Oriented Control and Direct Torque Control for a Five-Phase Fault-Tolerant Flux-Switching Permanent-Magnet Motor

This paper presents a comparative performance analysis of a new five-phase fault-tolerant flux-switching permanent-magnet(FT-FSPM)motor for high-reliability applications under the two most popular control schemes,namely,field-oriented control(FOC)and direct torque control(DTC)based on stator-flux orientation.Firstly,the new motor topology and structural characteristics are briefly presented.Secondly,the d-and q-axis for the FT-FSPM motor are defined,which is crucial to the mathematical model and control scheme,and the mathematical models are derived.Then,two control schemes,i.e.,FOC and DTC,and the main system are proposed.The operational principles of the two control schemes are presented,and space vector pulse width modulation(SVPWM)based on four neighboring vectors is adopted to reduce current harmonics and torque ripples.Finally,the simulated and experimental results are given,and performance analysis of the two control schemes are compared and discussed.The results reveal that FOC scheme has the sinusoidal phase current and low torque ripples,while the DTC scheme has fast dynamic response,verifying the effectiveness of the two proposed control schemes.This paper is a primary investigation for more possible improvements in the control schemes of the five-phase FS-FTPM motor.

Microstructures and dynamic processes within the five-phase system:Regarding COVID-19 as a complex system

The research uses the development of 2019 novel coronavirus disease(COVID-19)in the human body as an example to explore the microstructures and dynamic processes of a concise complex system from the lens of the five-phase system.Based on the structural balance theory and system dynamics,the research finds that Iransitive triads and cyclic triads in the fivephase system are both imbalanced.The integration of these differentiated triads comprises of a balaneed intermediate form in the shape of quadrangular cycles.These cycles serve as microstructures of the five-phase system,due to the inherent balancing feedback mechanism,and support the generation of resultants.The alter nation of quadra ngular cycles drives the spirali ng development of the whole system.By orderly and regular in terweaving of sig ned directed links,the research provides a holistic,process-oriented demonstrati on for the developme nt processes of COVID-19.It clarifies that the esse nee of the five-phase system is phase-tra nsition processes with the quadrangular cycle as carrier and supporter,rather than the static aggregati on of five elements.The research deep ens the understanding of system non linearity by visualizi ng the circular causality and promotes the academic dialogue between the Western process theory and the Chinese inherited notion of the fivephase system.

Dual-frequency Discontinuous Space Vector Pulse Width Modulation for Five-phase Voltage Source Inverters with Harmonic Injection

This paper proposes a dual-frequency discontinuous space vector pulse width modulation(DFDSVPWM)for a five-phase voltage source inverter with harmonic injection.In this modulation,for dual-frequency voltage output and reduction of switching losses,two different zero-vector-inserted modes are flexibly employed by alternatively using two types of zero vectors.Based on the comparison with continuous SVPWM,the idea and principle of the proposed DFDSVPWM are analyzed and an example of PWM signals for one bridge is also presented.For switching losses analysis,the impact factors and the calculation method are investigated and the corresponding implementation is given as well.The simulation and experimental results from a prototype verify the correctness and effectiveness of the proposed modulation and it has the advantages of outputting dual-frequency voltage and reducing switching losses.

Short-circuit fault-tolerant control for five-phase fault-tolerant permanent magnet motors with trapezoidal back-EMF

When a short-circuit fault occurs in a phase,the faulty phase needs to be removed artificially from the system because of the loss of the capability to generate torque.In this case,both the short-circuit current and phase-loss fault would generate additional torque ripples.In this study,a novel fault-tolerant control strategy is introduced to achieve low torque ripple operation of five-phase fault-tolerant permanent magnet synchronous motors with trapezoidal back electromotive force(FTPMSM-TEMF)in the event of a short-circuit fault.The key concept of this method is to compensate for the torque ripples caused by the short-circuit current and the adverse effect of the phase-loss.Based on the torque expression under fault conditions,the torque ripple caused by the short-circuit current can be offset by injecting a certain pulsating component into the torque expression in the phase-loss condition.This would result in smooth operation under fault conditions.Moreover,to track the fault-tolerant alternating currents,the model of the deadbeat current predictive control is extended and restructured for the fault condition.The effectiveness and feasibility of the proposed fault-tolerant strategy are verified by experimental results.

《运气商》五运六气诊疗特色探析

明代医家徐亦稚所撰《运气商》,对《黄帝内经》运气理论有所创悟。认为五运六气为阴阳五行所化生,六气各有主时,司天只主三之气,不可拘泥司天之说而不明间气;运气疾病的发生主要是由于运气的胜复变化,而人体于呼吸之间感受邪气,肺胃二脏首先受病;在诊断时要脉症合参,脉象的诊断不必以左手侯外感之说为拘,症状多见于肺胃二脏的异常变化;在用剂方面徐亦稚认为诸名医家所创方剂周详完备,所以并未收录以及创立方剂,而是提出了运气致病的处方用药原则当参以《内经》治法。其五运六气诊疗特色值得当代医家继承与发展。

五相感应电机变采样周期模型预测控制策略

针对无调制模块的模型预测控制器MPC(model predictive controller)存在的谐波含量高问题,提出1种新型基于模型的变采样周期MPC策略,并将其应用于五相感应电机驱动系统。分析了MPC对时间固定离散化所带来的问题,而引入调制或调制替代来解决此问题将使控制系统复杂度增加,故遵循更简单、自然的思路,基于追击算法来改变采样间隔,结合MPC确定最优控制动作和实施时间,实现变采样周期MPC方案。利用五相感应电机驱动系统开展实验,实验结果验证了新型变采样周期MPC优良的参考跟踪和电流谐波性能。

基于虚拟方波注入的五相永磁同步电机开路故障下直接转矩控制

在传统直接转矩控制(DTC)中,参考磁链往往是一个固定值,这将导致五相永磁同步电机(PMSM)在正常及容错情况下运行时效率不高。为解决该问题,该文提出一种基于虚拟方波注入的DTC(VSWI-DTC)策略。首先,建立五相PMSM在正常和开路故障情况下的数学模型,在同步旋转坐标系中推导出恒定转矩下电流幅值与定子磁链幅值的关系。其次,设计最优定子磁链探测器。通过向定子磁链幅值中注入虚拟方波信号,根据电流幅值的变化情况补偿定子磁链幅值,在线探寻最优定子磁链幅值。最后,与无差拍DTC相结合,实现电机高效率DTC运行。实验结果表明,所提策略不但能保持DTC良好的动态性能,抑制开路故障引起的转矩脉动,而且提高了电机在正常和开路故障情况下的效率。

运气学说指导下的乌梅丸临床应用体会

运气学说是中医学理论的基础,是中医学天人相应整体观的体现。学习五运六气,正确对待五运六气,对临床诊疗疾病具有积极的指导意义。乌梅丸为医圣张仲景所创,主治蛔厥、久利,经后世医家不断发挥,现已广泛应用于证见寒热错杂的内外妇儿诸多疾病。以运气学说指导乌梅丸应用时,要抓住厥阴枢机不利的病机,从辨天、辨人、辨病证三方面分析,当疾病在丑至卯时(厥阴病欲解时)发作或加重时,证属寒热错杂、阴阳不相顺接时,运气因素与“厥阴风木”相关时,乌梅丸常有良效。

辛丑年运气方治疗皮肌炎相关间质性肺疾病所致难治性咳嗽

基于五运六气理论,从整体恒动的观念出发,分析辛丑年运用五味子汤合备化汤治疗皮肌炎相关间质性肺疾病(DM-ILD)所致难治性咳嗽的疗效。辛丑全年,岁水不及,太阴湿土司天,太阳寒水在泉,整年气化以寒湿为主。寒湿为阴邪,易伤阳气,尤伤肾阳,故辛丑年防治疾病应注重扶阳温中。五味子汤和备化汤是陈无择根据辛丑年运气特点所创的运气方,二者配伍具有温肾健脾散寒、温肺化痰滋阴之效,恰合辛丑年DMILD所致难治性咳嗽的病机特点,故辛丑年以其治疗该病具有良好疗效。

地磁感应电流作用下三相五柱变压器无功功率定量分析

无功功率作为电力系统运行重要指标,其波动影响电力设备的安全稳定运行以及整个系统的电压稳定。为分析三相五柱变压器在地磁感应电流作用下的无功功率分布,根据变压器的实际参数,通过串联电阻及电压补偿的办法,建立三相五柱变压器磁场-电路耦合有限元计算模型,对不同大小地磁感应电流下的变压器无功功率进行定量分析。通过计算三相五柱空载及额定负载下无功功率的分布以及单相自耦变压器无功功率,发现随着地磁感应电流的增大,三相五柱空载及负载无功功率特性曲线均大体呈线性增加,且单相自耦变压器相较于三相五柱变压器无功曲线对于地磁感应电流更为敏感。并结合不同芯柱结构变压器的磁路特点,分析了无功差异变化的原因。研究结果可为地磁感应电流作用下三相五柱变压器稳定运行提供参考依据。

《三因极一病证方论》中天干方组方思路及应用

天干方是陈无择所创,首载于《三因极一病证方论》,是以运气理论为指导,以五行亢害承制规律为依照,运用药物四气、五味来治疗和预防岁运太过或不及而导致的人体已出现或可能出现的病证的10首方剂。其制方参照气味相和、阴阳动态平衡、五脏苦欲补泻、五行制化原则,针对岁运太过或不及,各有制方法度。治疗目的在于以偏纠偏,恢复人体气化的动态平衡。在应用时要注意识运气、观体质、辨病证,应用范畴涵盖岁运太过或不及致病和治未病。