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

In the field of high-power electric drives, multiphase motors have the advantages of high power-density, excellent fault tolerance and control flexibility. But their decoupling control and modulation process are much more complicated compared with three-phase motors due to the increased degree of freedom. Finite control set model predictive control can reduce the difficulties of controlling six-phase motors because it does not require modulation process. In this paper, a cascaded model predictive control strategy is proposed for the optimal control of high-power six-phase permanent magnet synchronous motors. Firstly, the current prediction model of torque and harmonic subspaces are established by decoupling the six-phase spatial variables. Secondly, a cascaded cost function with fault-tolerant capability is proposed to eliminate the weighting factor in the cost function. And finally, the proposed strategy is demonstrated through theoretical analysis and experiments. It is validated that the proposed method is able to maintain excellent steady-state control accuracy and fast dynamic response while significantly reduce the control complexity of the system. Besides, it can easily achieve fault-tolerant operation under open-phase fault.

A New Switching Sequences of SVPWM for Six-Phase Induction Motor with Features of Reduced Switching Losses

In this paper,new SVPWM switching sequences for six-phase asymmetrical induction motor drives are derived with the aim to reduce inverter’s switching losses.Total three switching sequences are introduced in this paper.These sequences are derived such that the phases get continuously clamped when a current of the phases is around its peak magnitude and hence reduced switching losses are recorded.The comparative performances of these modulation techniques are studied with two existing switching sequences.Simulation,analytical and experimental results are presented.Based on these results,it is found that new switching sequences reduce switching losses effectively in dual three phase inverters.

PSO Based Controlled Six-phase Grid Connected Induction Generator for Wind Energy Generation

This paper deals a detailed performance investigation of asymmetrical six-phase grid connected induction generator(GCIG)in two proposed configurations in variable speed operation.During the system development,regulation of DC-link voltage has been proposed using particle swarm optimization(PSO)based PI controller,ensuring the power flow to utility grid through back to back converters.The closed loop operation of asymmetrical six-phase GCIG using indirect field oriented control in different configurations has been carried out in Matlab/Simulink environment.Analytical results have been verified using real time test results on virtual platform of Typhoon HIL supported with some experimental validation.

Research on Open-circuit Fault Tolerant Control of Six-phase Permanent Magnet Synchronous Machine Based on Fifth Harmonic Current Injection

This paper proposes a novel control approach for fault-tolerant control of dual three-phase permanent magnet synchronous motor(PMSM) under one-phase open-circuit fault.A modified six-phase static coordinate transformation matrix and an extended rotating coordinate transformation matrix are investigated considering the influence of the fifth harmonic space on fault-tolerant control. These mathematical models are further analyzed in the fundamental space and the fifth harmonic space after the fault and to eliminate the coupling between the d-q axis voltage equation in the fundamental wave space and the d-q axis voltage equation in the fifth harmonic space, a secondary rotation coordinate transformation matrix is proposed. To achieve the purpose of reducing torque ripple, the fault-tolerant control method proposed in this paper not only takes the minimum copper loss as the constraint condition, but also injects the fifth harmonic current. The experimental result of current and torque is used to verify the accuracy of fault-tolerant control.

Research and Design of DTC System Based on Six-phase Asymmetrical BLDCM

In this paper,the torque ripple problem of six-phase asymmetrical brushless DC motor(BLDCM)is studied.First,the basic structure of BLDCM is introduced,and the operation principle of six-phase asymmetrical BLDCM that is studied in the thesis is expounded.Then,the principle of direct torque control(DTC)system of BLDCM is also discussed,and the improved system is proposed,including using the torque hysteresis loop and opening current hysteresis loop,and choosing the improved voltage vector to make the PWM-ON-PWM modulation.Finally,the DTC system simulation model is built,and the system is also tested by the experiment.According to the results of experiment and simulation,the DTC system designed in this thesis can control the six-phase asymmetrical BLDCM stably and reliably,and the problem of high frequency and torque ripple is solved well.

A novel current vector decomposition controller design for six-phase permanent magnet synchronous motor

The vector control algorithm based on vector space decomposition （VSD） transformation method has a more flexible control freedom, which can control the fundamental and harmonic subspace separately. To this end, a current vector decoupling control algorithm for six-phase permanent magnet synchronous motor （PMSM） is designed. Using the proposed synchronous rotating coordinate transformation matrix, the fundamental and harmonic components in d-q subspace are changed into direct current （DC） component, only using the traditional proportional integral （PI） controller can meet the non-static difference adjustment, and the controller parameter design method is given by employing intemal model principle. In addition, in order to remove the 5th and 7th harmonic components of stator current, the current PI controller parallel with resonant controller is employed in x-y subspace to realize the specific harmonic component compensation. Simulation results verify the effectiveness of current decoupling vector controller.

Small Signal Stability of Three-phase and Six-phase Synchronous Motors:A Comparative Analysis

Small signal stability analysis is conducted for an asymmetrical six-phase synchronous motor in comparison with its equivalent three-phase counterpart.For this purpose,a linearized model of the six-phase synchronous motor is developed using the dq0 approach,which is used in eigenvalue criteria to determine absolute stability in comparison with its equivalent three-phase counterpart.The analysis includes a comparison of the variation in evaluated eigenvalues associated with the stator and rotor sides according to changes in both the three and six-phase machine parameters and working conditions.Key analytical results are experimentally investigated and validated on a test rig.

Modeling and Analysis of Six-Phase Synchronous Motor under Fault Condition

Multi-phase machines(more than three-phase)are rigorously being investigated for various high power applications due to their increased power to weight ratio,increased frequency and reduced magnitude of torque pulsation,and fault tolerant characteristics.Fault analysis of a system is extremely important,not only to understand its operating characteristic,but it is also required prior to the design of suitable control/protective scheme.Therefore,the aim of this paper is not to devise a new mathematical model and control algorithm,but to investigate the behavior of six-phase synchronous motor(SPSM)under fault conditions caused by open circuit(OC)and short circuit(SC)at its input terminals as that has not been reported so far.Some key analytical results have been experimentally verified.

《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。

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。

不同坐标系下六相PMSM单相开路容错MPC控制

目的目前六相永磁同步电机单相开路故障的模型预测容错控制的研究已逐步成为热点,本文将对α-β和d-q2种坐标系控制下的故障机理进行对比分析,并对比不同坐标系中下正常和故障容错运行模型的控制效果。方法基于矢量空间解耦坐标变换矩阵不变原理,对A相开路进行故障模型的理论计算分析,分别在α-β和d-q这2种不同坐标系中对其进行模型预测控制容错建模。最后在MATLAB/Simulink中对2种坐标系下的电机正常运行和故障容错运行中的工作性能采用相同电机参数进行实时仿真。结果仿真结果显示,正常运行时,2种坐标系下总谐波失真(THD)值分别为2.09%和2.77%;故障运行时,d-q坐标系下的THD值比α-β坐标系小了13.15%;容错运行时2种坐标系下的THD值分别为1.19%和1.79%。结论从仿真结果可以看出,d-q坐标系控制下的电机在故障时具有更稳定的性能,而在正常和容错运行状态下,2种坐标系下的控制效果几乎等效。

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。

五运六气与绝经后骨质疏松症发生风险分析

目的研究五运六气与绝经后骨质疏松症是否存在关联性,以期为绝经后骨质疏松症的治疗提供新思路。方法选取1517例绝经后骨质疏松症患者,通过患者出生日期,推算天干、岁运、司天、主气、客气、主运、客运五运六气因素,判断其与绝经后骨质疏松症的相关性。结果绝经后骨质疏松症患者与出生时的天干、主气、主运及司天分布关联性分析,差异具有统计学意义(P<0.05),出生天干为甲年、主气为阳明燥金、主运为太羽、司天为阳明燥金患者更易罹患绝经后骨质疏松症。结论患者出生时的运气特点与绝经后骨质疏松症的发病风险相关。

MP-MMC驱动六相永磁同步发电机负载转矩观测前馈滑模控制

六相永磁同步发电机(PMSG)谐波含量较低、解耦方法成熟且稳定性强,具有广阔的应用前景。为提升六相PMSG负载转矩突变时的动态性能,增强系统的抗干扰能力,提出了一种利用负载转矩观测值前馈补偿的策略。首先,采用滑模观测器观测负载转矩,观测器滑模面设计为实际转速与观测转速之差,在观测过程中滤除了抖振信号,且未引起相位和幅值变化;其次,将负载转矩观测值按比例前馈至电流环给定值,弥补滑模控制器不连续项幅值不足的问题;再次,针对前馈比例常数过大导致转速无法快速稳定在给定值的问题,将前馈比例系数设为可变值;最后,基于Matlab/Simulink建立了多相模块化多电平换流器(MP-MMC)驱动六相PMSG负载转矩观测前馈滑模控制的仿真模型,对所提策略进行验证。仿真结果表明滑模观测器可准确观测负载转矩,前馈补偿策略有效抑制了负载突变引起的转速波动。

“异病同治”视域下应用审平汤辨治眼病思路探析

“异病同治”是中医辨证论治的精髓和实际应用,独具中医临床特色,是个体化治疗的具体体现。临证秉承“谨守象态、异病同治”原则,守法而不守方,灵活辨证结合运用,以三因司天方审平汤阖降阳明,治疗过敏性结膜炎合并激素性高眼压症、原发性开角型青光眼、青光眼睫状体炎综合征,皆得天相助,疗效显著。本文主要在“异病同治”视域下分析阳明阖降失司临床诊疗思路,以期拓宽三因司天方应用范畴,为临床提供借鉴意义。

计及退磁分析的电驱重构型车载充电系统

电驱重构型车载充电(EDROC)系统通过将驱动系统组件复用为充电系统,分时执行电驱和充电功能,能够有效降低成本和充电设备的体积占用。然而,在高温工况下EDROC系统中的永磁同步电机(PMSM)存在不可逆退磁的风险。鉴于此,本文通过分析电机在不同条件下退磁程度,进而提出电机在充电工况下安全运行边界。首先,分析EDROC系统在直流充电和边跑边充模式下的绕组电流;其次,建立电机不可逆退磁模型;然后,针对不同充电模式,详细分析不同温度和充电电流下电机退磁程度,并以此建立电机在充电工况下的安全运行边界;最后,基于一台2 kW实验样机开展实验,验证本文不可逆退磁模型的准确性以及安全运行边界对EDROC系统安全运行的必要性。

基于运气因素探讨心系疾病发病及用药规律——以辛丑年为例

五运六气理论是中医学理论的重要组成部分,是先人们在长期的生产生活过程中积累的宝贵经验,对疾病的发生、发展、预防、调护等方面有独到的见解。该文从五运六气角度出发,以辛丑年为例分析运气特点,探究运气因素对心系疾病发作的影响,总结用药规律。辛丑年水运不及,太阴湿土司天,太阳寒水在泉,根据各气特点加减:初之气佐以疏风通络,二之气佐以泻心火滋肾水,三之气佐以清暑利湿,四之气佐以健脾利湿,五之气佐以养阴润肺,终之气佐以温补阳气。辛丑年选药组方多燥之、温之,佐以运化脾胃、慎用寒凉,以防助湿,为治疗心系疾病提供新思路。

基于小波神经网络的六相永磁同步电机高阻连接状态感知策略

六相永磁同步电机具有缺相运行能力,因此必须对其高阻连接状态作出精准预判,以确保对故障线路实施有效切断,防止系统扰动引起保护误动作,并为容错控制提供可靠判据。基于矢量空间解耦方法建立了六相永磁同步电机完全解耦的数学模型,并建立其控制系统模型。采集正常状态与高阻连接状态下的电机信号,通过小波包分解提取其能量距特征,输入前向反馈神经网络进行离线训练,最后将其应用于剧烈变化工况下,在线感知高阻连接状态的发展态势。基于Matlab进行仿真,结果表明所提策略能够有效识别高阻连接状态,灵敏感知其发展态势,并在高阻故障发生前发出预警信号,同时对剧烈变化工况具有一定鲁棒性。

具有中点电压平衡与零序电流抑制的T型三电平逆变器供电六相PMSM-DTC

在三电平六相电机驱动系统中,存在中点电压不平衡及零序电流导致定子电流畸变等问题。为此,该文针对T型三电平逆变器供电的六相永磁同步电机,提出一种具有中点电压平衡与零序电流抑制功能的直接转矩控制(DTC)策略。为实现DTC的快速构建,该策略基于两电平三相电机DTC结构,利用精简后的开关状态,在六相绕组轴线上分别合成满足控制要求的4个电压矢量,然后通过两个滞环比较器结合简单的扇区划分,确定最优电压矢量所在轴线,同时构建中点电压与零序电流控制平面,并对系统在控制平面所处扇区进行判断。在此基础上,根据最优电压矢量所在绕组的相电流iy的极性,实现最优电压矢量的选择,并进一步构建DTC最优开关矢量表。最后,通过实验结果验证了所提控制策略的可行性和有效性。

集成型车载充电系统并网模式模型预测控制策略

相较于传统车载充电系统,集成型车载充电系统(integrated onboard charger system,IOCS)在成本、功率密度等方面具备显著优势。文中基于六相永磁电驱系统设计了一台IOCS,并研究了模型预测电流控制(model predictive current control,MPCC)算法在该系统并网模式下的应用。首先,分析所提IOCS的电路拓扑并建立数学模型,同时介绍传统MPCC的实施流程。然后,针对传统MPCC计算量大、稳态性能差等不足,提出一种基于占空比优化的MPCC(MPCC based on duty cycle optimization,DCO-MPCC)策略。一方面,减少备选电压矢量数量,降低电流预测环节带来的计算负担;另一方面,提出一种占空比优化技术,改善系统稳态性能。最后,通过实验验证了所提算法的有效性与优越性。实验结果表明,DCO-MPCC策略能够显著提升系统稳态性能并减少算法计算量。充电与车网互动(vehicle to grid,V2G)工况下,网侧电流总谐波畸变(total harmonic distortion,THD)分别降低6.18%与5.92%,算法运行时间减少17.54μs。