THREE-PHASE BRIDGE INVERTER FOR 9kW DOUBLY SALIENT PERMANENT MAGNET MOTOR

The three-phase bridge inverter is used as the converter topology in the power controller for a 9 kW doubly salient permanent magnet （DSPM） motor. Compared with common three-phase bridge inverters, the proposed inverter works under more complicated conditions with different principles for special winding back EMFs, position signals of hall sensors, and the given mode of switches. The ideal steady driving principles of the inverter for the motor are given. The working state with asymmetric winding back EMFs, inaccurate position signals of hall sensors, and the changing input voltage is analyzed. Finally, experimental results vertify that the given anal ysis is correct.

Speed Regulation Method Using Genetic Algorithm for Dual Three-phase Permanent Magnet Synchronous Motors

Dual three-phase Permanent Magnet Synchronous Motor(DTP-PMSM)is a nonlinear,strongly coupled,high-order multivariable system.In today’s application scenarios,it is difficult for traditional PI controllers to meet the requirements of fast response,high accuracy and good robustness.In order to improve the performance of DTP-PMSM speed regulation system,a control strategy of PI controller based on genetic algorithm is proposed.Firstly,the basic mathematical model of DTP-PMSM is established,and the PI parameters of DTP-PMSM speed regulation system are optimized by genetic algorithm,and the modeling and simulation experiments of DTP-PMSM control system are carried out by MATLAB/SIMULINK.The simulation results show that,compared with the traditional PI control,the proposed algorithm significantly improves the performance of the control system,and the speed output overshoot of the GA-PI speed control system is smaller.The anti-interference ability is stronger,and the torque and double three-phase current output fluctuations are smaller.

FCS-MPC for four-switch three-phase AC-DC converters with DC-link capacitor voltage balancing

Due to the decrease in the number of switches for the four-switch three-phase alternating current-direct current(FSTP AC-DC)converter,it can easily lead to DC-link capacitor voltage imbalance and the system stability reduction.In order to solve these problems,a finite control set model predictive control(FCS-MPC)for FSTP AC-DC converters with DC-link capacitor voltage balancing is proposed.In this strategy,in order to facilitate calculation,theαβcoordinate system model is established and all voltage vectors are evaluated by establishing a cost function.During the whole process,phase locked loop(PLL)and complex modulation strategy are not required.In the new established cost function,the additional objective term of suppressing capacitor voltage fluctuation is to eliminate effectively the capacitor voltages oscillations and deviations and improve the system reliability.The simulation results show that the proposed strategy can keep the capacitor voltage balancing and has good dynamic and static performance.

Microcontroller-Based Variable Speed Drive for Three-Phase Induction Motor in Cooling Applications

This paper presents an electronic VSD （variable speed drive） for three-phase IM （induction motor） using a microcontroller. The VSD is designed for cooling applications where the 1M is coupled to a cooling fan. The drive receives temperature feedback from objects to be cooled and output a corresponding frequency to the IM. A prototype of the VSD is constructed to control a 175 W, four pole, squirrel cage three-phase IM. The heart of the control circuit is a low-cost microchip＇s PICI6F777 microcontroller which is programmed using C language to generate variable frequency SPWM （sinusoidal pulse width modulation） switching signals. These switching signals are fed to an 1GBT inverter. The VSD constructed can be switched between two modes of speed control＂ automatic temperature-controlled mode and manual user-controlled mode. Cost savings using the prototype are demonstrated.

Switching of Capacitors in an Asymmetric Induction Motor with Single-Phase Power,Triggering Several Applied Loads

xThis study has as its objective to collaborate with the expansion in the market of electric energy in rural areas,offering as such an innovative prospect to the solution of associated problems through use of the asymmetric three-phase induction motor,supplied by a single-phase source.In this system,capacitor switching is applied during operation,while theoretical and practical results are presented for the application of this switching in a three-phase asymmetric induction motor of 20 hp.

Direct on Line Starting Induction Motor with Thyristor Switched Capacitor Based Voltage Regulation

The purpose of this paper is to show a laboratory scale implementation of a Thyristor Switched Capacitors （TSC） as an alternative for voltage regulation during a direct on line three-phase induction motor starting on an emulated weak transmission line. Thyristor switched capacitor bank was chosen because it is a well known topology, considering the very nature of the direct starting induction motors, which represents a highly inductive load, the use of switched reactors becomes unnecessary. Such fact minimizes the introduction of harmonics components, and also reduces the cost of the implementation. The binary disposition of the banks allows a variable Var compensation with sixteen steps, in this case. The solution makes use of low cost devices combined with sliding window voltage and current measurement algorithm and a PI control with dead band control for achieve the shown experimental results, where the system is able to manage a typically 20% voltage drop, reducing it to less than 4%. The schematic of the developed circuit, the control technique and a quite simple method to calculate the binary weight capacitors banks are also presented.

Performance Analysis of Optimization Based FOC and DTC Methods for Three Phase Induction Motor

Three-phase induction motors are becoming increasingly utilized in industrialfield due to their better efficiency and simple manufacture.The speed control of an induction motor is essential in a variety of applications,but it is dif-ficult to control.This research analyses the three-phase induction motor’s perfor-mance usingfield-oriented control(FOC)and direct torque control(DTC)techniques.The major aim of this work is to provide a critical evaluation of devel-oping a simple speed controller for induction motors with improving the perfor-mance of Induction Motor(IM).For controlling a motor,different optimization approaches are accessible;in this research,a Fuzzy Logic Controller(FLC)with Fractional Order Darwinian Particle Swarm Optimization(FODPSO)algorithm is presented to control the induction motor.The FOC and DTC are controlled using FODPSO,and their performance is compared to the traditional FOC and DTC technique.Each scheme had its own simulation model,and the results were com-pared using hardware experimental and MATLAB-Simulink.In terms of time domain specifications and torque improvement,the proposed technique surpasses the existing method.

New Approach to the Power Selection for Asynchronous Motor

The heating calculation of three-phase squirrel- cage asynchronous motor on the condition of starting for a prescribed rotary angle is firstly studied with time dissection method and its corresponding algorithm is provided. Then based upon the algorithm, a new method for motor power selection is established. Motor initial power determined by load power ischecked and modified in terms of time crit erion, heating criterion,and starting torque criterion.An appropriate motor power which meets three criterions is obtained at last, in the meantime, working displacement matrix andfrequency matrix used for control are acquired. Lifting motor of MDJ1800 low-level high- speed palletizer is taken as a reaI case in the paper.

Transient Analysis and Control Strategies for a Quad-lnverter Multiphase Multilevel Motor Drive in Faulty Conditions

In this paper, post-fault-tolerant control strategies for quad-inverter multiphase-multilevel induction motor drives are investigated. More specifically, four standard two-level three-phase VSIs （voltage source inverters） supplying the open-end windings of a dual three-phase induction motor is considered, quadrupling the power capability of a single VSI with given voltage and current ratings. In healthy conditions, the control algorithm is able to generate multi-level voltage waveforms, equivalent to the ones of a three-level inverter and to share the total motor power among the four dc sources in each switching period. This sharing capability is investigated under post-fault operating conditions, when one VSI must be completely insulated due to a severe failure on it. In this case, the conversion power unit can operate with a reduced power rating by a proper modulation of the remaining three VSIs. The whole ac motor drive has been numerically implemented, and the effectiveness of the proposed control strategies under healthy and post-fault operating conditions have been proved.

Towards Economic Single-Phase Motor

Studying of operation balance in single-phase induction motors is an issue of interest due to the need for reducing the power consumption and increasing the motors’ life. The paper focuses on improving the motor performance by balancing the stator phase operation for the most common-used connection diagrams of single-phase capacitor-run induction motors (SPCRIMs) and three-phase induction motors (TPIMs) operating from single-phase supply (SPS). Therefore, a mathematical model is used to balance the motor operation by varying the frequency supply voltage. Characteristics of balancing parameters are investigated, various methods of motor balancing are presented and comparisons were done among these balancing methods.

基于长周期暂态信号分析的电机驱动变换器直流母线电容在线状态监测

直流母线电容作为电机驱动变换器中最薄弱的元件之一,其老化会导致系统故障的概率增大,因此对电容老化进行在线监测至关重要。针对现有监测方法存在经济性差、采样频率高、影响系统正常运行等问题,提出一种基于长周期暂态信号分析的电容在线监测方法,用于估计电机驱动变换器直流母线等值串联电容(equivalent series capacitance,ESC)。首先,根据系统负载切换过程建立共节点感-容等值暂态模型,分析长周期暂态信号特点。其次,推导基于长周期暂态信号的在线监测模型,确定监测程序启动判定条件。然后,提出一种基于多项式重构的电容电流基线校准方法,消除传感器零漂影响,提高监测精度。最后,仿真和实验表明所提出方法的监测精度满足电容监测的要求。

计及总损耗功率的电动汽车母线电容主动快速放电方法

针对电动汽车遇到碰撞等紧急情况时,高压驱动系统母线电容电压需迅速降到安全电压(60 V),而传统基于PI控制的母线电容主动放电方法存在鲁棒性差、放电时间长和安全性低的问题,提出一种计及总损耗功率的电动汽车母线电容快速放电方法。首先,建立以永磁同步电机绕组作为泄放电阻的母线电容能量流动模型,将逆变器损耗、电机绕组铜耗、电机电感储能等损耗作为总损耗,利用扩展滑模观测器(ESMO)对总损耗功率进行估算,并通过Lyapunov稳定性理论对ESMO的稳定性进行了证明。然后,将观测的总损耗功进行前馈补偿,从而使母线电压快速降低并稳定在安全电压。仿真和实验结果表明,与现有主动放电方法相比,所提放电方法不仅显著减小了放电时间,而且提高了快速放电的鲁棒性和安全性。

主动参与惯性调频的船舶变频负载电机-电容协同控制方法

针对船舶变频负载参与系统惯性调频的难题,该文提出变频负载电容储能-电机转速协同的模型预测控制策略,实现变频负载中不同惯量资源主动响应和协同优化综合电力系统的动态频率。建立系统频率-电机转速-电容电压状态空间方程,提出电机-电容惯量响应系统频率变化的控制机理;建立考虑负载运行约束的系统频率预测模型,提出计及频率动态响应以及电机-电容最优调控性能的代价函数,并给出基于频率偏差约束的权重参数优化方法,实现变频负载的主动响应及电机-电容的协同控制。建立船舶综合电力系统RT-LAB半实物仿真模型,试验表明所提方法有效提升了电机-电容的自适应协同能力,使变频负载充分参与频率动态调节。

直流母线小电容永磁同步电机驱动系统网侧电流谐波抑制策略

直流母线采用小电容永磁同步电机驱动系统具有降低成本和延长运行寿命的优势。但在系统运行时网侧电流中存在大量的谐波,这将会影响网侧电流质量。为了改善小电容永磁同步电机(PMSM)驱动系统的网侧电能质量,该文提出一种基于阻抗重塑的有源阻尼控制方法,以抑制网侧电流谐波。通过对驱动系统进行建模,分析影响网侧电流谐波的因素,建立母线电流与网侧电流的数学关系。采用有源阻尼控制方法,提取母线电压谐波信号,以最优电压补偿的方式构建反馈回路,重塑驱动系统的特定频率处的等效阻抗,以实现网侧电流谐波的改善。同时,为了抑制电压补偿模块对电流内环扰动的影响,设计电流环级联双频陷波器,并通过系统极点图进行了稳定性分析。仿真结果和实验分析验证了所提控制方法的有效性。

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.

Analysis on Circulating Current and Split Capacitor Voltage Balance for Modular Multilevel Converter Based Three-phase Four-wire Split Capacitor DSTATCOM

We propose a modular multilevel converter(MMC)based three-phase four-wire(3P4W)split capacitor distribution static synchronous compensator(DSTATCOM),aiming at compensating unbalanced and reactive load currents.Due to the zero-sequence current compensation,the circulating current char-acteristics of 3P4W MMC-DSTATCOM are different from conventional MMCs.Moreover,the distinct working principle of IMMC would affect the features of split capacitor voltage.The decoupled positive-,negative-and zero-sequence second-order and DC components of the circulating current are deduced explicitly.Two proportional-integral controllers with dual dq transformation are employed to suppress the positive-and negative-sequence components of second-order circulating current,while quasi proportional-resonance controller is designed to eliminate the zero-sequence component.Besides,the phenomenon of the unbalanced split capacitor voltages is revealed,and fast-tracking balancing method by controlling zero-sequence current flowing through the split capacitors is provided.Digital simulation results verify the accuracy of the analysis and the feasibility of the suppression methods.

10 kV串联补偿电容器对异步电动机启动的影响研究

目前,配电网存在的主要问题为网架薄弱、电网结构不合理、导线截面偏小、供电半径偏大、配电变压器数量和大容量电机负荷增长迅速及负荷功率偏低等,这些问题导致配电线路沿线电压跌落严重、线损高、功率因数低、输送容量小、电压闪变频繁等。为此本文首先介绍了10 k V串联电容器补偿的工作原理、主要组成以及安装位置和容抗选择,然后分析了异步电动机等效模型,最后通过Matlab仿真,研究了串联补偿电容器不同的安装位置、容抗的大小、并联电阻等情况下,串联补偿电容器对异步电动机启动的影响,为串联电容器补偿装置的设计和工程实践提供了有益的参考。

Fault-tolerant stator flux oriented decoupling control for dual three-phase permanent magnet motor without diagnosis and reconfiguration

In this paper,the fault-tolerant capability of the existing stator-flux-oriented decoupling control(SFOC)for the DTP-PM motor is investigated,and a simple fault-tolerant SFOC is further designed to enhance fault tolerance.Firstly,the mathematical model of the DTP-PM motor in the stator-flux-oriented rotating coordinate system is analyzed.An SFOC is proposed to guarantee healthy operation performance,considering torque,flux linkage,and harmonic currents.Secondly,the coupling relationship under open-phase conditions is assessed.The assessed result shows that the coupling relationship between the harmonic and fundamental components results in conflicts and poor post-fault operation.Thirdly,the proposed SFOC includes an automatic deactivation module to detect conflicts with a variable threshold.The conflicted harmonic current controllers can be excluded automatically.Hence,fault-tolerant control can be remedied without diagnosing the specific fault scenario,and excellent faulttolerant capability can be achieved.Finally,experiments on a DTP-PM motor are carried out to verify the feasibility and effectiveness of the proposed strategy.

异步电动机自动内补偿技术的研究

异步电动机的三V形接法,是分别将主绕组Wa1、Wb1、Wc1的首端连接为A1、B1、C1,并将副绕组Wc2、Wa2、Wb2的末端对应联接,构成夹角为60度的V形接线,引出九个接线端;用接于三对或三个接线端的主电容器C01、C02、C03进行主导的电流内补偿,并用接于三对接线端的副电容器C04、C05、C06配合调节器进行PWM控制动态调节,达到功率因数接近1.0的内补偿效果;可将三相绕线式转子绕组短时与副绕组三端联接,并用三相调节器进行重载的电机起动。