On-line estimation and compensation scheme for dead time and inverter nonlinearity independent of parameter variations in PMSM drive

A new on-line compensation scheme that can exactly estimate the dead time and inverter nonlinearity even under the parameter variations is proposed for a PWM inverter-fed permanent magnet synchronous motor drive. The proposed scheme is based on the fact that the sixth-order harmonic component in total disturbance estimated under the presence of various uncertainties is mainly caused by the dead time and inverter nonlinearity. The total disturbance due to the parameter variations as well as the dead time and inverter nonlinearity is estimated by the adaptive scheme. From this total disturbance, the sixth-order harmonic component is extracted through the harmonic analysis. The obtained sixth-order harmonic is processed by the PI controller to estimate the disturbance only caused by the dead time and inverter nonlinearity in the stationary reference frame. The effectiveness of the proposed scheme is verified through the comparative simulations and experiments using DSP TMS320F28335. Without requiring an additional hardware, the proposed scheme can effectively compensate the dead time and inverter nonlinearity even under the parameter variations.     

LQG/LTR control of an AC induction servo drive

A new design method based on the linear-quadratic-Gaussian with loop-transfer-recovery (LQG/LTR) theory has been developed for the design of high performance AC induction servomotor drives using microcomputer-based digital control. The principle of field orientation is employed to achieve the current decoupling control of an induction motor. An equivalent model representing the dynamics of the decoupled induction motor has been developed. Based on the developed model with specified parameter uncertainties and given performance specifications, a frequency domain loop-gain-shaping method based on the LQG/LTR theory is proposed for the design of the servo loop controller. A microcomputer-based induction servomotor drive has been constructed to verify the proposed control scheme. Simulation and experimental results are given to illustrate the effectiveness of the proposed design method     

Adaptive backstepping control and friction compensation for AC servo with inertia and load uncertainties

An adaptive backstepping control with friction compensation scheme is presented. A third-order linear dynamic model is used for the AC motor control system design while the LuGre dynamic friction model with nonuniform friction force variations characterizes the friction force. Nonlinear adaptive control laws are designed to compensate the unknown system parameters and disturbances. System robustness and asymptotic position tracking performance are shown through simulation and experimental results.     

导引头随动系统中信号处理延迟的影响及其补偿算法

新体制导引头的信号处理方式越来越复杂,造成了非常明显的信号处理延迟,这种纯延迟环节又严重影响着导引头随动系统的跟踪能力.首先采用相位裕度的概念定量分析了延迟大小对随动系统带宽的影响,然后针对目标、导弹、导引头空间运动关系的特点,介绍了一种基于机动目标"当前"统计模型和自适应Kalman预测滤波的探测器信号处理延迟补偿方案,采用探测器输出的跟踪误差和电位器输出的角度信息重构视线运动量测值,利用Kalman滤波获得当前时刻视线角位置的最优估计,进而得到当前时刻跟踪误差的预测值,取代被延迟的跟踪误差进行随动系统的闭环控制,仿真表明本方案有效可行.     

A nonlinearity compensation method for a matrix converter drive

This paper presents a new method to compensate the nonlinearities for matrix converter drives. The nonlinearities of matrix converter drives such as commutation delay, turn-on and turn-off time of the switching devices, and on-state switching device voltage drop is corrected by a new matrix converter model using the direction of current. The proposed method does not need any additional hardware or complicated software and it is easy to realize by applying the algorithm to the conventional vector control. The proposed compensation method is applied for high-performance induction motor drives using a 3-kW matrix converter system without a speed sensor. Experimental results show the proposed method provides good compensating characteristics.     

Analysis and validation of a real-time AC drive simulator

This paper presents the analysis and validation of a real-time AC drive simulator. Real-time simulation has been used for over a decade in power systems engineering to test controllers thoroughly, efficiently, and safely. The development and testing of large DC drives could benefit from this type of simulation, but real-time power system simulators have modeling restrictions preventing stable and accurate simulation of isolated drives switching at high frequencies. These restrictions can be overcome by combining in a single model both the power converter and motor models. After discussing the salient issues related to the real-time simulation of DC drives, a prototype real-time simulator for drives is described. Its ability to accurately emulate the behavior of large drives is demonstrated through two case studies. A first case study demonstrates the feasibility of simulating a drive of typical complexity in real-time. The second case study demonstrates how the controller for a PWM VSI fed induction motor, switching at 4 kHz, is designed, implemented in a microcontroller and tested in real-time using a simulated inverter, motor and load. Comparisons against results obtained with another simulation tool, which uses extremely accurate variable-step integration algorithms, demonstrates the validity of our approach.     

液压四足机器人伺服阀驱动电路设计

随着机器人应用的扩展,液压四足机器人作为一种特种机器人,因其高度的机动性和大负载能力而受到人们的高度重视。在液压系统中,阀控动力系统通过控制伺服阀来调节流入执行元件中的液压油流量,从而控制液压执行元件。事实上,由于控制输入信号一般比较微弱,因此控制输入信号需要利用控制放大器处理和功率放大后才能用于控制伺服阀工作。提出了一种伺服阀驱动电路的设计方案,该驱动电路同时驱动一条腿的三个伺服阀工作,通过Multisim进行仿真分析后,研制了电路板。最后利用半实物仿真设备搭建测试系统的控制模型,并经该驱动板进行功率放大,结果表明该驱动电路运行稳定可靠,满足了设计要求。     

Fuzzy optimization techniques applied to the design of a digital PMSM servo drive

This paper presents a novel design approach by applying gradient optimization with fuzzy step-sizing techniques to the design of a digital permanent magnet synchronous motor (PMSM) servo drive. The servo specifications and design variables are specified and analyzed to formulate a controller optimization problem. The servo responses are then fed back to evaluate the overall system performances, which can be expressed as objective functions with respect to the servo control parameters. According to the objective functions and design specifications, the servo control parameters can be properly tuned toward their optimal values by using the proposed optimization techniques. In order to improve the convergent rate of the optimization process, a fuzzy-logic based step-size tuning strategy is presented. Because of the nonlinear property of the digital servo drives, the tuned servo control parameters may be only optimal for a particular operating point, therefore, once the optimum design is achieved, the proposed fuzzy optimizing controller can perform as an intelligent tuner for on-line gain adaptation under different loading conditions. The proposed fuzzy optimization servo tuner has been realized under a PC-MATLAB-based environment with an on-line controlled digital PMSM servo drive. Simulation and experimental results indicate that the control parameters of a digital PMSM servo drive can be optimized for its dynamic responses under various load conditions.     

Analytical analysis of the harmonic effects of a PWM AC drive

A novel analysis is presented of the harmonic content of current, torque pulsations, and harmonic copper losses of a three-phase induction machine fed by a two-phase pulsewidth modulation (PWM) inverter. The purely analytical results are based on the assumption that the switching frequency is high compared with the fundamental frequency. It is shown that the results hold accurately for frequency ratios f_s /f₁>9     

A novel circuit for dead angle compensation in the DC-to-DCconverter controlled by a magnetic amplifier

A novel circuit for compensating the dead angle in the DC-to-DC converter controlled by a magnetic amplifier is presented. The proposed circuit suppresses the dead angle so that the core loss may be reduced. The behavior of this circuit is explained analytically and a condition for compensation is derived theoretically. By adding this compensation circuit, excellent control characteristics of the converter are obtained without spoiling the current surge suppression characteristics of the magnetic amplifier     

缝纫机专用交流伺服系统设计

提出了一种基于DSP交流伺服系统。交流伺服系统是缝纫机控制系统的核心部分,因此详细研究交流伺服控制系统对整个系统将有非常重要的意义。重点介绍了硬件电路设计及软件模块设计。通过实践应用表明,本设计是一种简单而高效的控制系统,可以应用于各种工业缝纫机控制系统。     

Design and analysis of a high bandwidth disk drive servo systemusing an instrumented suspension

Resonance modes in the suspension of hard disk drives limit the closed-loop bandwidth. The bandwidth of the servo can be increased by active vibration control of the resonance modes. This paper considers the optimal placement of strain gauge sensors on a suspension to observe the vibration states of the suspension. Using a finite-element simulation of an actual suspension, a state-space model is identified for the two normal strains and the shear strain at each finite element. The state-space model includes the dynamics of the three primary resonance modes. A numerical search algorithm is used to determine the sensor location and orientation which maximizes the minimum singular value of the observability grammian. With the strain gauge output signal, a multirate inner loop controller is designed to be used with the existing head-positioning system. Simulations and analysis results suggest that use of an instrumented suspension is a viable candidate method for improved disk drive servo performance     

Discrete-time LQG/LTR design and modeling of a disk drive actuatortracking servo system

This paper presents the discrete-time LQG/LTR design of a disk drive track following servo system. The servo compensator designed through linear-quadratic Gaussian control combined with loop transfer recovery (LQG/LTR) consists of a Kalman filter for state estimation and state feedback for control. The desired tracking servo performance is first formulated through a frequency shaped return ratio of the Kalman filter and subsequently recovered at the output of the plant/compensator loop through the automatic design of a discrete-time linear quadratic (LQ) regulator. Particular attention has been given to modeling the calculation time delay and bias force estimation. The excellent robustness and performance characteristics of a continuous time LQG/LTR design are theoretically unachievable due to the extremely low sampling rate and nonminimum phase plant characteristics. However, both time and frequency domain simulations show that reasonable stability margins and performance can still be recovered. This technique nearly eliminates all the trial and error typical of a conventional pole placement design of a similar system. The direct discrete-time design can handle extremely low sampling rates associated with embedded servo systems. The technique can also be used for designing multi-rate and multi-input servo systems     

Rotor time constant updating scheme for a rotor flux-orientedinduction motor drive

This paper presents a simple online rotor time constant identification scheme of an indirect field-oriented induction motor for the purpose of improving the performance and robustness of the drive. The proposed technique neither requires any special test signal nor any complex computations. This scheme is based on a special switching technique of the current-regulated pulsewidth modulation (CRPWM) voltage-source inverter (VSI), which allows measuring the induced voltage across the stator phase. The rotor time constant is then identified directly from this measured voltage. This proposed technique provides six windows within one electric cycle to update the rotor time constant, which should be sufficient for all practical purposes. Simulated results followed by experiments are presented to validate the effectiveness of the proposed technique     

A discrete time variable structure controller for a brushless DCmotor drive

The design and the microprocessor-based implementation of a variable-structure-strategy (VSS) controller for a brushless DC motor drive are described. The controller is a conventional variable-structure design in the continuous-time domain. However, the microprocessor implementation using a constant sample period implies that full sliding mode is not achieved. The properties of the quasi-sliding that results are explored. It is shown that the sliding line expands into a sliding region, which can be described as a sector. The size of this sector is related to the sampling period and the switching gains. A modified design procedure is proposed for discrete-time VSS design. The design was verified on an experimental set-up, which generated variations in system parameters as well as external load disturbances     

GMDH-based modeling and feedforward compensation for nonlinear friction in table drive systems

This paper presents a novel mathematical model-based feedforward compensator design for the nonlinear friction in table drive systems using the Group Method of Data Handling (GMDH). In the proposed approach, the nonlinear friction can be autonomously modeled as a polynomial expression for appropriate control state variables according to the process of GMDH and, as a result, the complicated structural modeling and its parameterization, indispensable to conventional model-based strategies, can be completely eliminated. In addition, since the proposed GMDH-based model can achieve the generalization ability for table drive conditions, the robust compensation for friction can be attained against the change of drive conditions. Experimental verifications using a table drive system of actual machine tools show the significant performance improvement of the proposed algorithm in the trajectory control with velocity reversal motion.     

步进电机和交流伺服电机性能综合比较

作为做离散运动的设备,步进电机在控制过程中表现出与交流伺服电机相似性特征。但是两者之间存在运行效果与应用性上的差异。所以在进行生产运行的过程中应当进一步加强对两种电机之间的性能比较分析。     

Compensated carrier PWM synchronization: a novel method to achieveself-regulation and AC unbalance compensation in AC fed converters

The compensated carrier PWM synchronization (CCPS) method for AC-fed PWM power converters is presented. The method provides a solution to PWM converters fed by industrial power systems (IPSs). Such environments usually present unbalances and magnitude fluctuations of AC voltages. Those circumstances impair standard PWM techniques because low-order harmonics are produced and DC-link regulation is poor. To reduce these undesirable effects produced by IPS, a method based on using independently compensated carriers per phase was conceived. In particular, CCPS prevents second harmonic generation and achieves converter self-regulation. The method can be used with any PWM technique and bidirectional power flow. The evaluation of CCPS is based on a complete performance comparison of a PWM rectifier with and without CCPS for various known PWM techniques     

Development of new training algorithms for neuro-wavelet systems on the robust control of induction servo motor drive

A robust wavelet neural network control (RWNNC) system is proposed to control the rotor position of an induction servo motor drive in this paper. In the proposed RWNNC system, a wavelet neural network controller is the main tracking controller that is used to mimic a computed torque control law, and a robust controller is designed to recover the residual approximation for ensuring the stable control performance. Moreover, to relax the requirement for a known bound on lumped uncertainty, which comprises a minimum approximation error, optimal network parameters and higher order terms in a Taylor series expansion of the wavelet functions, an RWNNC system with adaptive bound estimation was investigated for the control of an induction servo motor drive. In this control system, a simple adaptive algorithm was utilized to estimate the bound on lumped uncertainty. In addition, numerical simulation and experimental results due to periodic commands show that the dynamic behaviors of the proposed control systems are robust with regard to parameter variations and external load disturbance.