Analysis of PWM current source GTO inverter with PWM-controlledthyristor rectifier for induction motor drive

With the application of an energy rebound circuit for the pulsewidth modulation (PWM)-controlled rectifier, an improved current source gate turn-off thyristor (GTO) inverter system capable of producing sinusoidal inputs and outputs is presented. The energy rebound circuit in the inverter is used to turn off the thyristors in the rectifier for applying PWM control techniques and also to clamp the spike voltage produced in the inverter circuit. The principles and circuit operations of this system are described in detail, and requirements for PWM control of the rectifier are investigated. The conditions for satisfying the requirements of the energy rebound circuit are analyzed by experimental and theoretical methods. The PWM-controlled current source GTO inverter system is used to drive an eight-pole 400 Hz 5.5 kW induction motor. Analytical and experimental results, as well as the characteristics of the motor drives, are given     

The effect of link current ripple on the torque pulsations in a current source inverter-fed induction motor

This paper analyses the effect of link current ripple on the torque pulsations of a current source inverter-fed induction motor. The torque pulsations produced by a ‘pure’ DC link current are compared with those produced by a link current containing both DC and a superimposed ripple. It shows that if the average values of link current in the two cases are the same, the magnitudes of the torque pulsations with and without ripple are approximately equal in the time domain, although the magnitudes of the individual torque harmonics are affected. It also investigates the effects of different inverter frequencies on the torque pulsations.     

Sensorless control of inverter-fed induction motor drives

Sensorless control is considered to be a lower cost alternative than the position or speed encoder-based control of induction motors. Two popular sensorless control methods, namely, the model reference adaptive system (MRAS) and the Luenberger observer (LO) methods are compared for speed and torque control characteristics. They are also compared against the well-known vector control principle. For the drive system simulated, the torque and speed obtained from sensorless control are almost identical to those obtained from the vector control method. However, the torque ripple for the sensorless methods is observed to be higher than vector control-based method. The MRAS method introduces higher torque ripple when compared to the Luenberger observer. In addition, speed estimation methods employed in sensorless control are more sensitive to motor parameter variations.     

Quasi-resonant inverter-fed direct torque controlled induction motor drive

A quasi-resonant inverter-fed induction motor operated under direct torque control (DTC) scheme is modeled and analyzed with SABER simulator. The dc link voltage is clamped to source voltage. All the devices in the resonant link and inverter except auxiliary switch in the resonant link are operated soft under zero-voltage switching (ZVS). The auxiliary switch is turned on under zero-current switching (ZCS), but turned off hard. This scheme has been implemented on a laboratory-sized experimental setup. A comparison of simulation and experimental results under identical operating conditions were presented.     

基于PWM可控变换器的接地残流全补偿控制方法研究

针对配电网中传统全补偿消弧装置接地残流实时补偿能力差且在故障恢复后长期处于谐振状态而不能及时退出的问题,提出基于PWM可控变换器的接地残流全补偿控制方法.对全补偿消弧装置的消弧原理进行了详细分析,并利用主动频率注入法实现对地电容的精确检测.从理论上推导了零序电压与接地残流分量的关系,提出单相接地残流全补偿的实时控制方法...     

Five-level GTO inverters for large induction motor drives

The development of large induction motor drives with low torque ripple and fast dynamic response for new or retrofit applications has been limited by the device ratings and problems of series connections. This paper investigates the use of a five-level GTO voltage-sourced inverter for large induction motor drives. The advantages of such a drive are that single GTO thyristors may be used at each level, thereby avoiding the need for series connection of the thyristors. The thyristors are well protected from overvoltages by the clamping action of the DC supply capacitors. The disadvantages are that each DC level requires a separate supply, four in the case of the five-level inverter, and that the devices are not equally loaded. This paper reviews the basic operation of the five-level inverter and possible PWM voltage/frequency control techniques for the specific application of induction motor drives. The simulation results clearly show the unequal loading of the devices and the need for independent voltage supplies for the five levels. It is shown that a combination of several PWM techniques offers the best solution for the drives application. The conclusions indicate that large induction motors with ratings up to 22 MVA, 7.46 kV may be supplied by the five-level inverter using available 4.5 kV, 3.0 kA GTO thyristors. The recommended supply for such an inverter with full regenerative operation over the complete speed range is four, four-quadrant converters in a quasi-24-pulse configuration     

On the steady-state analysis of the inverter-fed induction motor

Contents The analysis of the induction motor based on the signal flow graphs is carried out. It is shown that the state transition matrix can be determined in a systematic and straightforward way using Mason's gain formula. This method is found computationally very much superior to other methods available in the literature. There is a considerable reduction in the CPU time. The presence of an input signal also does not pose any problems, as inherently the transition signal flow graph includes its effect also.

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Das stationäre Verhalten der stromrichter-gespeisten Asynchronmaschine

Übersicht Es wird in der vorliegenden Arbeit das stationäre Verhalten der stromrichter-gespeisten Asynchronmaschine auf Grund des Signalflußdiagramms untersucht. Die Anwendung der Masonschen Regel liefert unmittelbar die, State Transition Matrix' mit einem CPU-Zeitaufwand, der geringer ist, als der der in der Literatur bekannten Methoden. Beliebige Eingangssignale lassen sich in einfacher Weise behandeln, da diese im Signalflußdiagramm repräsentiert werden können.

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List of Symbols i _ds,i _qs direct and quadrature axis currents of stator - i _dr,i _qr direct and quadrature axis currents of rotor - i _dr(0),i _qs(0) initial values of d-q currents of stator - i _dr(0),i _qr(0) initial values of d-q currents of rotor - I _ds(s),I _qs(s) Laplace transforms of d-q currents of stator - I _dr(s),I _qr(s) Laplace transforms of d-q currents of rotor - L _s,L _r Self inductances of stator and rotor - M Mutual inductance between stator and rotor - R _s,R _r Resistance per phase of stator and rotor windings - R ₁,R ₂,R ₃,R ₄ Roots of characteristic equation - V _ds V _qs Direct and quadrature components of stator voltage - _ds, _qs Direct and quadrature components of stator flux linkages - _dr, _qr Direct and quadrature components of rotor flux linkages - _s Synchronous angular velocity - _r Rotor angular velocity - T _d Torque developed     

Decoupled direct control for PWM inverter-fed induction motor drives

A new direct torque and stator flux control method is presented for pulsewidth modulation (PWM) inverter-fed induction motors. This new strategy, called decoupled direct control (DDC), is based on a decoupling matrix that allows for the separate control of the stator flux and the torque. This method is compared to the well-known direct field-oriented control (FOC) and stator flux vector control (SFVC) methods. Two DDC-based methods are presented. The first determines the stator voltage vector such that the torque and the flux track their respective reference trajectories in one sampling time. The second sets separately the dynamic behavior of the torque and stator flux errors by the use of proportional-plus integral (PI)-type controllers. These methods take into account the full motor dynamics without the need of a coordinate transformation and reduce significantly computation requirements compared to FOC and SFVC. The two proposed strategies have been implemented experimentally and comparisons with FOC and SFVC were carried out. The obtained results show the effectiveness of the proposed PI-DDC strategy.     

Control techniques for multiple current source GTO converters

This paper presents the control techniques for a multiple current source GTO power converter in a high-power environment. The output current space vector diagram for the multiple power converter is presented. The important issue of DC current sharing between the two bridges is discussed, and a novel current sharing control scheme based on the use of redundant switch combinations is presented. Harmonic issues are discussed. The ranges of independent control of real and reactive power for different DC power sources are presented     

基于变频器网侧电流感应电机定子故障诊断

提出一种基于变频器网侧电流频谱分析的感应电机定子故障诊断方法。当感应电机发生定子故障时,定子电流负序分量将通过逆变器、整流器向变频器网侧传播,将在网侧电流频谱中出现故障特征频率成分。分析电网负序电压对感应电机定子电流、变频器网侧电流的影响,发现电网负序电压分量在网侧电流中形成的故障特征频率与定子故障时的网侧电流故障特征频率存在明显不同,选择容易测取的网侧电流可构成定子故障诊断新判据。实验结果表明:利用变频器网侧电流频谱分析能有效进行定子故障诊断,且不受电网负序电压的影响。     

Analysis of inverter-fed high-speed induction motor consideringcrosspath resistance between adjacent rotor bars

The purpose of this work is to analyze the steady state performance of an inverter-fed high-speed induction motor with trapezoidal rotor bars taking into account crosspath resistance between adjacent rotor bars. The performance of the induction motor drives for various crosspath resistances of two kinds of rotor slot shapes, a rectangular bar and a trapezoidal bar, is discussed on the basis of theoretical and experimental results of a 2.2 kW 500 Hz 15000 rev/min three-phase induction motor. It is also shown that the equivalent rotor resistance and leakage reactance change with crosspath resistance between adjacent rotor bars for various values of the fundamental supply frequency, the rotor slip, and the harmonics. The results of this research will be applied for design consideration of a high-speed induction motor with uninsulated rotor bars     

电流控制电压源逆变器驱动的感应电机逆解耦控制

在转子磁链坐标系下,以电流控制电压源逆变器供电驱动电机运行.通过在电流内环采用高增益控制器,感应电机模型中的2个定子电流分量可近似为定子参考电流,从而可忽略定子电流动态特性的影响,将以定子电压为控制量的感应电机四阶模型降阶成以定子电流为控制量的二阶模型.采用状态反馈线性化方法求得感应电机的逆系统,将多变量、非线性、强耦合的感应电机动态解耦成转速与转子磁链2个一阶子系统.在此基础上,设计一种积分比例(IP)控制器对解耦子系统进行闭环控制.电流内环采用滞环比较器,直接获得PWM信号,控制逆变器实现电流跟踪,从而使调速系统具有快速的动态响应性能.仿真结果验证所提控制方案的有效性和优越性.     

A new simultaneous gating GTO dual converter-fed DC motor drivewithout circulating current

A new dual power converter, comprised of two three-phase AC-DC pulse width modulated (PWM) gate turn-off thyristor (GTO) converters, is proposed. The gating pulse pattern of the converters is chosen such that no circulating current flows between the converters when they are operated simultaneously. In addition, a good input power factor is obtained with less ripple in the output current. A symmetrical type of gating is worked out in which all the GTOs in the converter are switched an equal number of times during each cycle of the source voltage. The motor current is free to reverse naturally at any moment, and hence, the possibility of discontinuous conduction of the motor current does not arise. A four quadrant, closed loop, speed controlled DC motor drive fed from the proposed dual converter is designed, constructed, and tested. The experimental results obtained are shown to be in good agreement with theory