Control of a converter system for an asymmetrical parameter type two-phase induction motor drive operating in motoring and generating modes

The control of a converter system is presented and discussed for an asymmetrical parameter type two-phase induction machine drive that is operating in motoring and generating modes. The proposed system consists of back-to-back voltage source converters. For a machine side, a three-leg voltage source converter provides both unbalanced and balanced two-phase output voltages with a scalar V/F control based on a carrier space vector pulse width modulation (SVPWM) technique. For a front end, a single-phase AC/DC doubled voltage converter with hysteresis current control is used to keep DC-link voltage constant, thus resulting in a bi-directional power flow operation for the motoring and generating modes. A closed-loop design for the DC-link voltage is fully given and also included is a review of carrier-based SVPWM for two-phase three-leg VSI. The proposed drive system was both simulated using MATLAB/SIMULINK and implemented on digital microcontrollers. The comparative performance evaluation of the whole system between balanced and unbalanced two-phase voltages for the machine is given. The simulation and experimental results show that the unbalanced phase voltage offers better performance for the whole system.     

Z源逆变器在异步电动机中的应用

近年来,间接磁场定向控制(IFOC)的异步电机驱动由于其效率高、稳定性能强及功率因数高,被广泛应用在高性能驱动系统中。本文采用IFOC技术来控制异步电机的速度大小,并使用Z源逆变器,即在逆变器主电路前加上一对阻抗(LC)网络,通过控制直通占空比,可以实现升/降压功能、提高异步电机的效率。     

Recurrent wavelet neural network controller with improved particle swarm optimisation for induction generator system

A recurrent wavelet neural network (RWNN) controller with improved particle swarm optimisation (IPSO) is proposed to control a three-phase induction generator (IG) system for stand-alone power application. First, the indirect field-oriented mechanism is implemented for the control of the IG. Then, an AC/DC power converter and a DC/AC power inverter are developed to convert the electric power generated by a three-phase IG from variable frequency and variable voltage to constant frequency and constant voltage. Moreover, two online trained RWNNs using backpropagation learning algorithm are introduced as the regulating controllers for both the DC-link voltage of the AC/DC power converter and the AC line voltage of the DC/AC power inverter. Furthermore, an IPSO is adopted to adjust the learning rates to further improve the online learning capability of the RWNN. Finally, some experimental results are provided to demonstrate the effectiveness of the proposed IG system.     

Five-leg inverter PWM technique for reduced switch count two-motor constant power applications

Industrial applications often require a number of variable speed electric drives. In the majority of cases, these multi-motor drive systems require independent control of individual motors. Over the past decade, research efforts have been made to reduce the number of power electronic devices required in multi-motor drive systems in order to reduce the overall complexity and hence cost of the drive. It has been shown recently that it is possible to independently control two three-phase induction machines using a five-leg voltage source inverter (VSI) as the supply, with one inverter leg being common to both machines. The existing pulse-width modulation (PWM) methods for this supply topology either limit the amount of DC bus voltage available to each machine or lead to uneven and increased switching frequency across five legs of the VSI. A new PWM method that effectively utilises the standard three-phase modulators in conjunction with appropriate modifications to generate modulation signals for all five legs of the VSI is presented. It enables an arbitrary distribution of the available DC bus voltage between the two machines. The considered supply topology, when utilised in conjunction with the developed PWM technique, is well suited to constant power applications such as centre-driven winders. Verification of the developed modulation method and its applicability to winder systems are demonstrated by experimental testing that includes both steady state and transient operation.     

FPGA-based adaptive backstepping control system using RBFN for linear induction motor drive

A field-programmable gate array (FPGA)-based adaptive backstepping control system with radial basis function network (RBFN) observer is proposed to control the mover position of a linear induction motor (LIM). First, the indirect field-oriented mechanism is adopted for controlling the LIM. Next, a backstepping control law is designed step by step for the tracking control of periodic reference trajectories, in which the uncertainties are lumped by a conservative constant. However, the lumped uncertainty is unknown and difficult to obtain in advance in practical applications. Therefore an RBFN is derived to observe the lumped uncertainty in realtime, and an adaptive backstepping control system with RBFN observer is resulted. Then, an FPGA chip is adopted to implement the indirect field-oriented mechanism and the developed control algorithms for possible low-cost, high-performance industrial applications. The effectiveness of the proposed control scheme is verified by some simulated and experimental results. By using the adaptive backstepping control system with RBFN observer, the FPGA-based LIM drive possesses the advantages of good transient control performance and robustness to uncertainties in the tracking of periodic reference trajectories.     

Vector control design and experimental evaluation for the brushless doubly fed machine

A new vector control algorithm for the brushless doubly fed machine (BDFM) has been developed. The goal of BDFM control is to achieve a similar dynamic performance to the doubly fed induction machine (DFIM), exploiting the well-known induction motor vector control philosophy. For this purpose, a recently developed unified reference-frame model has been used to develop the vector control strategy. The theoretical considerations for the vector control design, control loops tuning and limits are shown. In addition, practical considerations for the experimental implementation of vector control for the BDFM are shown. Experimental results in a machine prototype confirm the good dynamic performances of this type of control.     

Modeling and identification of the multi-axis drive system using support vector machine and granular computing

Advanced manufacturing technology requires high-precision capability in multi-axis computer numerical control (CNC) machine tools. At present, the modeling and identification for the drive system of CNC machine tools has some defects. In order to solve the problem, some interdisciplinary theories and methods, such as support vector machines, granular computing, artificial immune algorithms, and particle swarm optimization algorithms, have been used to model and identify multi-axis drive systems for CNC machine tools. An identification method using a support vector machine, based on granular computing, is presented to identify a multi-axis servo drive system model for improving the precision of model identification, and an immune particle swarm optimization algorithm, based on crossover and mutation functions, is proposed to optimize the structure parameters of the support vector machine based on granular computing. The proposed identification method was evaluated by experiments using the multi-axis servo drive system. The experimental results showed that the proposed approach is capable of improving modeling and identification precision.     

Analytical closed-form investigation of pwm inverter induction motor drive performance under dc bus voltage pulsation

The voltage unbalance conditions at the input rectifier stage of the AC?DC?AC rectifier-inverter fed induction motor drive is analysed. This unbalance can cause significant voltage harmonic of twice the line frequency 2f1 in the DC bus. This voltage ripple can have a degrading effect on the induction-machine performance characteristics. The authors present an analytical closed-form mathematical model and analysis of the impact of DC bus ripple voltage of the three-phase voltage source inverter with the space-vector PWM on the induction machine phase voltages, currents and torque pulsations. The analytical expressions for the voltage and current space vectors as a function of the DC bus voltage pulsation are derived. Using superposition, the separate parts of the motor currents can be determined. From the current space vectors, the torque behaviour is estimated, again as a function of DC link voltage pulsation. Next, it is shown that the DC link voltage ripple components may cause large torque pulsation. The proposed analytical method is based on the mixed p?z approach, enabling presentation of the results in lucid and closed form. To verify the effectiveness of the proposed analytical model, experimental results based on laboratory setup were obtained.     

The effect of clearance control on the performance of an oil-free linear refrigeration compressor and a comparison between using a bleed flow and a DC current bias

A moving magnet type oil-free linear compressor has been designed for applications such as electronics cooling. A control system using a solenoid operated valve was developed for DC offset and axial clearance control. Operation of the linear compressor with a fixed clearance of 0.8 mm was compared with a zero DC offset operation. The fixed clearance operation requires a higher power input.The mean piston position can be controlled by using a DC bias on the drive voltage or by using a bleed flow from the compressor body to the suction side of the compressor. Using a DC bias on the drive voltage induces a higher power loss than using a bleed flow when there is a small radial clearance between the piston and cylinder. This provides evidence that the piston control in a refrigeration system with capacity control should be for a zero DC offset using a bleed flow.     

Experimental determination of mechanical parameters in sensorless vector-controlled induction motor drive

High-performance industrial drives widely employ induction motors with position sensorless vector control (SLVC). The state-of-the-art SLVC is first reviewed in this paper. An improved design procedure for current and flux controllers is proposed for SLVC drives when the inverter delay is significant. The speed controller design in such a drive is highly sensitive to the mechanical parameters of the induction motor. These mechanical parameters change with the load coupled. This paper proposes a method to experimentally determine the moment of inertia and mechanical time constant of the induction motor drive along with the load driven. The proposed method is based on acceleration and deceleration of the motor under constant torque, which is achieved using a sensorless vector-controlled drive itself. Experimental results from a 5-hp induction motor drive are presented.     

异步驱动电机扭矩波动对电动汽车纵向冲击影响的仿真研究

对电动汽车异步驱动电机在转子磁场定向矢量控制中因电机参数变化导致磁场解耦不完全,致使电机输出扭矩波动和扭矩及速度跟踪可能失效,进而带来纵向冲击和影响乘坐舒适性的问题进行了研究和分析,并在此基础上进行了电机控制策略的仿真分析.基于多体系统动力学建立了整车纵向动力学模型,并与控制系统一起建立了耦合仿真模型.利用所建立的耦合模型进行了电动汽车美国联邦循环工况(UDC)的仿真计算,计算结果表明所提出的矢量控制方法是可行的,能够有效改善电动汽车的纵向冲击问题.     

敏感用户高品质交-直流级联供电方案研究

工业过程中大量使用的变频器(variable frequency drive,VFD)在采用传统交流供电时易受到电压暂降影响,传统治理方式存在检测延时、控制复杂等问题。为此,该文从敏感负荷变频器在电网扰动工况下的供电需求量化出发,围绕供电拓扑设计、DC/DC变换器的控制策略及储能单元容量配置等方面,构建一种实用化工业用交-直流级联供电方案。该文利用电压暂降过程中直流供电回路与敏感负荷间的压差自感应控制,实现交-直流供电回路无扰动切换,提高电压暂降治理响应的快速性;采用两相交错并联DC/DC变换器接入集中式储能,减少储能系统纹波系数,并给出两相均流控制方法。最后,通过Matlab/Simulink中的建模仿真与样机的实验测试,验证所提方案能够在交流系统发生不同严重程度电压暂降过程中为各类敏感负荷提供稳定的连续供电,为解决工业敏感用户高品质供电问题提供可实用的新思路。     

高性能模糊控制裹包机的感应电动机驱动系统的设计与实现

针对接缝式裹包机的交流调速系统控制精度较差的问题,提出了具有模糊控制器的有限周期控制的感应电动机驱动.由于转矩和磁通是由有限周期控制技术调节,能达到极快转矩响应.将模糊控制器应用于速度控制反馈环节中,使该驱动系统具有高自适应能力,且对参数和工作条件改变是非常的不灵敏.     

Implementation of feedback-linearization-modelled induction motor drive through an adaptive simplified neuro-fuzzy approach

A simple modified version of neuro-fuzzy controller (NFC) method based on single-input, reduced membership function in conjunction with an intuitive flux–speed decoupled feedback linearization (FBL) approach of induction motor (IM) model is presented in this paper. The proposed NFC with FBL remarkably suppresses the torque and speed ripple and shows improved performance. Further, the modified NFC is tuned by genetic algorithm (GA) approach for optimal performance of FBL-based IM drive. Moreover, the GA searches the optimal parameters of the simplified NFC in order to ensure the global convergence of error. The proposed simplified NFC integrates the concept of fuzzy logic and neural network structure like a conventional NFC, but it has the advantages of simplicity and improved computational efficiency over the conventional NFC as the single input introduced here is an error (speed and torque) instead of two inputs, error and change in error, as in the conventional NFC. This structure makes the proposed NFC robust and simple as compared with conventional NFC and thus, can be easily applied to real-time industry application. The proposed system incorporated with different control methods is also validated with extensive experimental results using DSP2812. The effectiveness of the proposed method using FBL of IM drive is investigated in simulation as well as in experiment with different working modes. It is evident from the comparative results that the system performance is not deteriorated using the proposed simple NFC as compared to the conventional NFC; rather, it shows superior performance over PI-controller-based drive.     

Direct control algorithm for doubly fed induction generators in weak grids

An algorithm utilising direct feedbacks of torque and reactive power for the control of a doubly fed induction generator (DFIG) is proposed. Although the algorithm is based on field-oriented control, the algorithm calculates the feedback and feed-forward variables in the stator reference frame to reduce the number of coordinate transformations. Since the algorithm uses a single-loop approach instead of a cascaded loop design, the tuning of the controller is easier and the response time is faster when compared to those of most existing methods. The internal model control (IMC) design method is used in the proposed scheme to formulate the controller parameters. Measures on the possible voltage variations are included to increase the robustness of the system. Computer simulation and experimental implementation are reported. The results show that the algorithm can control the torque and reactive power independently. Harmonic distortions generated by the system are not noticeable because of the use of constant switching frequency.     

Three-Dimensional Magnetic Effects in Permanent-Magnet Magnet Synchronous Machines

This paper presents the results of an investigation of the three-dimensional (3-D) magnetic effects in permanent-magnet synchronous machines (PMSMs). Using 3-D finite-element analysis, effects of geometry and also a high-frequency excitation on the magnetic parameters of the machine have been studied. According to our findings, high-frequency phenomena come into effect at excitation frequencies of the order of a few kilohertz, which is not uncommon when the machine is operated at super high speeds. Our results show that normalized torque productivity is a function of stack length and an increase in stack length results in an increased torque density. It is also observed that an increase in excitation frequency decreases the self inductance of the stator windings while the phase difference between the flux linkage and magnetomotive force increases. This is a significant finding, especially the shift in the phase of the air gap flux, as it has a direct impact on the accuracy of the controller that drives the PMSM under field-oriented control. Another significant observation was the reduction in the induced voltage (back electromotive force) in a search coil located in the stator slots at high frequencies. Such observations mandate the use of 3-D analysis of machine geometry to optimize performance throughout the machine's speed range.     

Dynamic control of the permanent magnet-assisted reluctance synchronous machine

A digital signal processor-based control system for the permanent magnet-assisted reluctance synchronous machine, with the emphasis on dynamic performance, is proposed. A classical design approach is used to design the current and speed controllers for the machine. The stator current of the machine is controlled in such a way that the current angle in the dq synchronous reference frame is constant. The load-torque is estimated using a state space observer and compensation current based on the estimated load is used to improve the dynamic performance of the drive. The control system design is machine specific as it relies on data from finite-element analysis. Simulated and measured results on a 110-kW power level show that the resulting control system is stable and robust with good dynamic performance     

THE DESIGN AND IMPLEMENTATION OF SELF-COMMISSIONING TECHNIQUES FOR A VECTOR-CONTROLLED INDUCTION MOTOR DRIVE

ABSTRACT

This paper presents the design and implementation of self-commissioning techniques for a vector-controlled induction motor drive. Two key techniques are involved in the self-commissioning of a vector-controlled induction motor drive. The identification of the electric and mechanical parameters of motor and load, and the tuning of controller parameters that are to meet performance specifications in the various vector control loops, are proposed. The proposed techniques are further verified by experiments. Close simulation and experimental results are obtained.     

Harmonics reduction in standalone DFIG-DC system by shunt active filter controlled in stator flux reference frame

The presence of diode rectifier in standalone Doubly Fed Induction Generator-Direct Current (DFIG-DC) system leads to considerable current, voltage and torque harmonics and requires reactive power from the machine. A unique shunt active filter arrangement is proposed for addressing these requirements. The DC Link of DFIG-DC itself acts as input to shunt active filter and there is no requirement of creating and regulating a separate one. Since the stator flux reference frame is known in FOC of DFIG-DC system; the same can be used as PLL for the generation of current references for harmonics and reactive compensation in active filter control scheme. Hence, the AC voltage sensing is not needed in the proposed active filter control. In this paper, it is shown that current, voltage and torque harmonics are reduced with the help of shunt active filter, which have lower rating compared to the rotor side converter. The proposed scheme is verified by detailed experiments on a 5.5 kW slip-ring induction machine.     

压电式提花经编机自升压节能控制电路设计

针对提花经编机压电贾卡针（piezo jacquard needle,PJN）的驱动电路存在功耗高、需要额外的高压电源等问题,设计了一种将自升压电路和工作电路集成为具有能量回收功能的新型PJN驱动电路。基于压电陶瓷晶片的压电方程和PJN结构,介绍了PJN的工作原理,详细分析了所提出的PJN驱动电路的工作模态,给出了电路模态转换的脉冲宽度调制（pulse width modulation,PWM）控制策略。新型PJN驱动电路采用储能电感器代替传统驱动电路的限流电阻器,不仅能够限制PJN的正向充电电流,减少能量损耗,而且可以利用从低压电源吸收的能量将PJN的低压供电电源自适应升压至工作状态所需的高压。为了验证电路的自升压过程,进行了仿真分析。仿真结果表明,该新型PJN驱动电路具有自升压功能,无须外接高压工作电源,仅需低压供电电源即可以高压驱动PJN,能有效降低功耗,实现节能环保,具有广阔的工程应用前景。