共查询到20条相似文献,搜索用时 453 毫秒
1.
Torque ripple analysis and dynamic performance of a space vector modulation based control method for AC-drives 总被引:2,自引:0,他引:2
A constant switching frequency torque control method is presented in this paper, that uses flux error vector based space vector modulation (SVM) to achieve steady state and dynamic control of torque. The effect of SVM switching on torque ripple has been analyzed using "flux ripple vectors". This approach is used to develop an insight of torque ripple and to estimate it for any operating angular velocity. We propose a method of compensation to maintain steady state control of torque in the overmodulation region of operation. During torque dynamic, the optimum maximum switching state vector is selected. This gives a response similar to that obtained using direct torque control (DTC) and direct self control (DSC) methods. The proposed method is verified experimentally. 相似文献
2.
Direct method of overmodulation with integrated closed loop stator flux vector control 总被引:1,自引:0,他引:1
Tripathi A. Khambadkone A.M. Panda S.K. 《Power Electronics, IEEE Transactions on》2005,20(5):1161-1168
Overmodulation achieves full utilization of installed dc link voltage, by modifying the magnitude and the phase of reference voltage vector. Due to the nonlinear behavior in this region, closed loop vector control becomes difficult. A simple method of overmodulation with closed loop control of stator flux vector is proposed in this paper. Instead of modifying the voltage reference by nonlinear equations or look up table, we propose a direct method to generate the switching times. In so doing, the average angular velocity of the stator flux vector is controlled linearly throughout the modulation range. The proposed method shows lower harmonic distortion compared with existing methods. It greatly reduces the complexity and cost of achieving overmodulation over existing schemes. 相似文献
3.
A dead-beat type digital controller for the direct torque control of an induction motor 总被引:1,自引:0,他引:1
Joong-Hui Lee Chang-Gyun Kim Myung-Joong Youn 《Power Electronics, IEEE Transactions on》2002,17(5):739-746
In this paper, a dead-beat type digital controller has been introduced to overcome the problems of a conventional direct torque controller. The proposed induction motor drive with a digital dead-beat controller shows good transient response and negligible steady-state error even at a low switching frequency, which is needed for high power machines used for transportation. Including the rotor dynamics, the stability condition and steady-state error of the proposed control system have been examined in the z-plane. In addition, the good performance has been verified through the simulation and experiment. The flux and torque controllers have been designed with only stator voltage equations in the stator flux reference frame in order to take advantages of the direct torque control. Therefore, the proposed flux and torque controllers have simple forms and can be easily designed and implemented. 相似文献
4.
Stator flux based space-vector modulation and closed loop control of the stator flux vector in overmodulation into six-step mode 总被引:1,自引:0,他引:1
This paper presents closed loop control of stator flux vector in a wide operating range that can be used in torque control. A predictive control achieves zero phase error at constant switching frequency. Space vector modulation based on stator flux error vector is used to achieve control of stator flux over the entire range including overmodulation and six-step. During dynamics the fastest possible flux vector change is employed similar to the direct torque control. Experimental results are provided for a wide speed range and effect of parameter variation is studied. 相似文献
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Khoucha F. Lagoun S. M. Marouani K. Kheloui A. Benbouzid M. E. H. 《Industrial Electronics, IEEE Transactions on》2010,57(3):892-899
7.
A novel direct torque controlled interior permanent magnet synchronous machine drive with low ripple in flux and torque and fixed switching frequency 总被引:12,自引:0,他引:12
Lixin Tang Limin Zhong Rahman M.F. Hu Y. 《Power Electronics, IEEE Transactions on》2004,19(2):346-354
A modified direct torque control (DTC) scheme for interior permanent magnet synchronous machine (IPMSM) is investigated in this paper, which features in very low flux and torque ripple and almost fixed switching frequency. It is based on the compensation of the error flux linkage vector by means of space vector modulation. Modeling and experimental results show that the flux and torque ripples are greatly reduced when compared with those of the basic DTC. With the new scheme, very short sampling time is not essential. All the advantages of the basic DTC are still retained. In addition, fixed switching frequency at different operating conditions becomes possible. The field-weakening control of this drive is also studied; an IPM DTC drive with a wider operation range and lower flux and torque ripple has been achieved experimentally. 相似文献
8.
Overmodulation strategy for high-performance torque control 总被引:1,自引:0,他引:1
Jul-Ki Seok Joohn-Sheok Kim Seung-Ki Sul 《Power Electronics, IEEE Transactions on》1998,13(4):786-792
In the overmodulation region, the operation of the electrical drive system with a current controller is characterized by a rapid deterioration of motor torque and speed. It is desirable to use the overmodulation strategy, which guarantees the fast response even in transient state and satisfies the overall closed-loop control performance. In this paper, in order to improve the dynamic characteristics of the electrical drive, a new overmodulation technique is proposed. Considering the current transition characteristics, an efficient overmodulation strategy is introduced to achieve better transient performance through an adequate voltage selection. With the help of a new overmodulation strategy, required electrical torque can be directly produced as quickly as possible, and stable drive characteristics can be achieved in the transient condition. The proposed method has been implemented on an actual inverter system and thoroughly tested on a 900-W interior permanent magnet synchronous machine (IPMSM) to confirm its feasibility 相似文献
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10.
在传统异步电动机直接转矩控制方案中,由于负载的变化规律不可预测,因此其常会带来较大的开关频率的变化,为此提出了一种基于预前控制的异步电动机直接转矩控制的方法。该方法依据前一个周期的磁链和转矩误差,对下一个开关周期所应施加到异步电动机的定子电压矢量进行预测,然后借助空间矢量PWM的方法,合成此开关电压矢量。样机实验结果表明,该方案不但能维持逆变器的开关频率基本恒定,而且还具有比传统直接转矩控制更为优良的动静态特性。 相似文献
11.
Nemec M. Nedeljkovic D. Ambrozic V. 《Industrial Electronics, IEEE Transactions on》2007,54(4):2009-2017
This paper proposes a new concept for the control of voltage-source inverter (VSI)-fed induction machines. The method uses a predictive algorithm and can be split into two parts. The purpose of the first part, i.e., predictive torque control (PTC), is to predict the stator reference flux vector corresponding to the reference torque at the end of the sampling interval. The second part of the method provides accurate tracing of the stator reference flux by selecting either an active or a zero voltage vector. This approach is called immediate flux control (IFC), where two possible variants are suggested. In the first variant, a simple and fast algorithm obtains minimal stator flux error by impressing either an active or a zero voltage vector throughout the entire sampling interval. Consequently, the switching frequency becomes very low, but current and torque ripple are considerable. The second IFC variant generates the stator flux more accurately by applying an active voltage vector only throughout a calculated time slot within a sampling interval, whereas, during the remaining time of the sampling interval, a zero voltage vector is impressed. As a result, higher switching frequency arises, but it is still lower than that with space vector modulation. Both IFC variants, together with PTC, require minimal processing time and were efficiently implemented in a digital signal processor, which controlled a 3-kW induction machine drive. The obtained experimental results confirm the validity of the proposed approach. 相似文献
12.
Habetler T.G. Profumo F. Griva G. Pastorelli M. Bettini A. 《Power Electronics, IEEE Transactions on》1998,13(1):125-133
A self-tuning control scheme for stator-flux field-oriented induction machine drives in electric vehicles operating over a wide speed range is discussed in this paper. The stator flux can be determined accurately from the terminal voltage when the machine is operating at high speed. However, at low speed, the stator resistance must be known to calculate the stator flux. The problem of calculating the stator flux accurately over the entire speed range is addressed. The rotor flux can be found from the machine speed and rotor time constant. The stator flux, at low speed, is then calculated directly from the rotor flux. By alternating between these two methods of determining the stator flux, a self-tuning operation is achieved, wherein the stator and rotor resistances are periodically updated. Since both methods of determining the stator flux are forced to track one another, a smooth transition between flux estimators is obtained. The torque and flux are then controlled in a deadbeat fashion. Good torque control over a wide speed range can therefore be obtained. With the proposed scheme, the advantages of direct torque control are obtained over the entire speed range with the addition of a speed sensor 相似文献
13.
Kerkman R.J. Leggate D. Seibel B.J. Rowan T.M. 《Industrial Electronics, IEEE Transactions on》1996,43(1):132-141
Pulse width modulated (PWM) inverters experience a reduction in gain when overmodulation occurs. The pulse dropping or transition region is examined for continuous and discontinuous modulation strategies. Transition region characteristics for a number of modulation strategies are introduced. The effect of the transition region on field oriented control (FOC) is presented. The adverse effects of bus disturbances on current regulated AC inverters, while in the transition region, are demonstrated by experimental results. The problems encountered are the consequence of the reduced gain of the PWM inverter regardless of the PWM strategy. A compensated modulation technique (CMT) adaptable to continuous and discontinuous modulators eliminates the voltage error and transitions to six-step operation without inducing a voltage transient. The CMT applies to voltage and current regulated PWM inverters employing most of the modern switching strategies. Experimental results presented in the paper demonstrate the CMT's smooth transition to six-step and the improved performance a CMT-PWM algorithm provides 相似文献
14.
Operating voltage-source pulsewidth-modulated (PWM) inverters in the overmodulation region extends their voltage and power ranges. Proper operation in this region is of particular importance in AC motor drives. This paper presents a classification algorithm for the implementation of the space vector modulation (SVM) in the pulse-dropping region. It is demonstrated that the proposed algorithm allows smooth transitions through the entire operating range up to square wave operation. It does not require approximations and guarantees exact positioning of the switching instants. In addition, it is shown that the harmonic distortion can be kept lower than with conventional techniques in most of the overmodulation region. The technique requires less computational time, when compared with the conventional SVM methods. The results of the theoretical and mathematical analysis are verified on a 2-kVA prototype unit using a digital signal processor (DSP)-based controller 相似文献
15.
Adaptive high bandwidth current control for induction machines 总被引:2,自引:0,他引:2
For high performance induction machine control, the technique of indirect rotor flux oriented vector control is commonly utilized. The torque performance of this technique is significantly affected by the performance of the current control loops. In this paper a new adaptive high bandwidth current controller for induction machines is presented. The technique is derived and validated through simulation and experimental results. The new architecture is shown to achieve a dead-beat response, with a rise time of one sample period and no overshoot, when the inverter voltage limit is not exceeded. When the voltage limit is exceeded the current response is achieved in a minimum time with no overshoot. It is shown that the new control technique achieves similar dynamic response to the conventional dead-beat control scheme while eliminating parameter sensitivity issues. It is demonstrated that the new algorithm offers higher bandwidth than the commonly used synchronous frame proportional plus integral control technique while maintaining good steady state performance. 相似文献
16.
This paper investigates the operation of four space vector-based synchronized pulse-width modulation (PWM) strategies in the overmodulation zone using three different overmodulation algorithms. It is shown that the symmetries in the PWM waveforms generated can be preserved in the overmodulation zone also. With any given overmodulation algorithm, the voltage control characteristics (i.e., fundamental voltage versus control variable) are found to vary with PWM strategy, pulse number and type of clamping. The inverse of the appropriate voltage control curve is used during premodulation to maintain the modulator gain constant. The differences in the nature of the voltage control characteristics with the different overmodulation algorithms are brought out. These characteristics are compared and contrasted against those at high switching frequencies. The harmonic distortion in the different cases is evaluated and compared. It is shown that the bus clamping strategies perform better than the conventional strategy with any given overmodulation algorithm employed. These strategies, which exploit the flexibilities in the space vector approach, are useful in high power drives on account of their superior waveform quality at low switching frequencies and high DC bus utilization. 相似文献
17.
Many solutions to provide continuous operation of adjustable speed drives (ASDs) during power grid disturbances have been proposed, but they are all applied to DC-link ASD. In this paper a new solution to provide limited ride-through operation of a scalar controlled direct frequency converter (DFC) for a duration of hundreds of milliseconds, without any hardware modification, is presented. During the ride-through operation, the drive is not capable of developing torque or to control the motor flux. By recovering the necessary power to feed the control hardware, the DFC is able to keep the ASD operating. When normal grid conditions are re-established, the DFC is also able to accelerate the motor from nonzero speed and flux by initializing the modulator with the estimated frequency and initial voltage vector angle. The duration of the ride-through operation depends on the initial motor flux, speed level, rotor time constant, load torque and inertia 相似文献
18.
In this paper, a simple direct torque control (DTC) method for sensorless matrix converter drives is proposed, which is characterized by a simple structure, minimal torque ripple and unity input power factor. Also, a good sensorless speed-control performance in the low speed operation is obtained, while maintaining constant switching frequency and fast torque dynamics. It is possible to combine the advantages of matrix converters with the advantages of the DTC strategy using space vector modulation a deadbeat algorithm in the stator flux reference frame. Experimental results are shown to illustrate the feasibility of the proposed strategy. 相似文献
19.
The matrix converters, which are direct power electronic converters, are able to provide important benefits such as bidirectional power flow, sinusoidal input currents with adjustable displacement angle, and a great potential for size reduction. Still, two major disadvantages exist: a lower than unity voltage transfer ratio and high sensitivity to power grid disturbances. Many solutions to provide continuous operation of adjustable speed drives (ASDs) during power grid disturbances have been proposed, but they are all applied to DC-link ASD. In this paper, a new solution to provide limited ride-through operation is presented with a matrix converter using a scalar controlled induction motor for a duration of hundreds of milliseconds, without any hardware modification. During the ride-through operation, the drive is not able to develop torque or to control the motor flux. By recovering the necessary power to feed the control hardware of the matrix converter, it is able to keep the ASD operating. When normal grid conditions are reestablished, the matrix converter is able to accelerate the motor from nonzero speed and flux by initializing the modulator with the estimated frequency and the initial angle of the reference output voltage vector. The maximum duration of the ride-through operation depends on the initial motor flux, speed level, rotor time constant, load torque, and inertia. This method is verified on a laboratory setup with a matrix converter 相似文献
20.
Space vector pulse width modulation of three-level inverter extending operation into overmodulation region 总被引:7,自引:0,他引:7
Mondal S.K. Bose B.K. Oleschuk V. Pinto J.O.P. 《Power Electronics, IEEE Transactions on》2003,18(2):604-611
Multilevel voltage-fed inverters with space vector pulse width modulation have established their importance in high power high performance industrial drive applications. The paper proposes an overmodulation strategy of space vector PWM of a three-level inverter with linear transfer characteristic that easily extends from the undermodulation strategy previously developed by the authors for neural network implementation. The overmodulation strategy is very complex because of large number of inverter switching states, and hybrid in nature, that incorporates both undermodulation and overmodulation algorithms. The paper describes systematically the algorithm development, system analysis, DSP based implementation, and extensive evaluation study to validate the modulator performance. The modulator takes the command voltage and angle information at the input and generates symmetrical PWM waves for the three phases of an IGBT inverter that operates at 1.0 kHz switching frequency. The switching states are distributed such that the neutral point voltage always remains balanced. An open loop volts/Hz controlled induction motor drive has been evaluated extensively by smoothly varying the voltage and frequency in the whole speed range that covers both undermodulation and overmodulation (nearest to square-wave) regions, and performance was found to be excellent. The PWM algorithm can be easily extended to vector-controlled drive. The algorithm development is again fully compatible for implementation by a neural network. 相似文献