永磁直驱风力发电机自抗扰技术及其无位置传感器控制策略

针对永磁直驱风力发电机传统矢量控制动态性能差,抗扰动能力弱的问题,提出一种双环线性自抗扰控制系统。在此基础上针对传统滑模观测器抖振等因素造成的速度和位置角观测误差较大的问题,提出改进型自适应滑模观测器。结果表明所设计的速度和电流双环线性自抗扰控制策略能有效提高转速跟踪性能和电流波形质量;在滑模观测器的基础上结合自适应算法精确观测反电动势,借鉴锁相环原理代替反正切函数估算出转子转速和位置角,相比传统滑模观测器具有更高的估算精度。     

A novel robust adaptive sliding mode control using stochastic gradient descent for PEMFC power system

This study represents a comparison of novel robust adaptive sliding mode control using stochastic gradient descent (ASMCSGD) versus the super twisting algorithm (STA) for the proton exchange membrane fuel cell (PEMFC) power system. PEMFC has been constantly encountered with external disturbances such as inlet gas pressures and temperature fluctuations which a novel adaptive control law should be designed to be robust against the mentioned perturbations. The proposed ASMCSGD is based on the conventional sliding mode control (SMC), which guarantees robustness and restraining external disturbances. As is common, the main drawback of conventional SMC is the generation of a chattering phenomenon. Therefore, by using the stochastic gradient descent (SGD), a novel adaptive control law is designed. Hence, the SGD can continuously calculate the adaptive gain and then guarantee robustness besides minimizing the chattering phenomenon. The stability of the PEMFC power system for both controllers ASMCSGD and STA is demonstrated via the Lyapunov theorem. Simulation results have been studied and illustrate the effectiveness of the proposed controller successfully using Matlab/Simulink.     

An adaptive sliding mode observer based near-optimal OER tracking control approach for PEMFC under dynamic operation condition

Tracking control of oxygen excess ratio (OER) is crucial for dynamic performance and operating efficiency of the proton exchange membrane fuel cell (PEMFC). OER tracking errors and overshoots under dynamic load limit the PEMFC output power performance, and also could lead oxygen starvation which seriously affect the life of PEMFC. To solve this problem, an adaptive sliding mode observer based near-optimal OER tracking control approach is proposed in this paper. According to real time load demand, a dynamic OER optimization strategy is designed to obtain an optimal OER. A nonlinear system model based near-optimal controller is designed to minimize the OER tracking error under variable operation condition of PEMFC. An adaptive sliding mode observer is utilized to estimate the uncertain parameters of the PEMFC air supply system and update parameters in near-optimal controller. The proposed control approach is implemented in OER tracking experiments based on air supply system of a 5 kW PEMFC test platform. The experiment results are analyzed and demonstrate the efficacy of the proposed control approach under load changes, external disturbances and parameter uncertainties of PEFMC system.     

基于FFT的直驱式波浪发电系统功率优化控制

针对实际波浪的不规则性、扰动性以及滑模变结构控制中存在明显抖振和开关动作产生高频纹波问题,采用快速傅里叶变换对波浪激励力进行频谱分析。通过矢量叠加原理构造最大波浪能捕获策略,建立直驱式波浪发电系统模型。采用自适应快速终端滑模变结构控制方法实现最优功率状态跟踪控制,提高抗干扰性和实现限时收敛,同时利用卡尔曼滤波滤除纹波和减少抖振,结合Lyapunov函数分析系统稳定性。仿真结果表明,快速傅里叶变换(FFT)可满足未知不规则波浪的功率最优跟踪要求,所提滑模控制方法可实现快速跟踪,准确跟随,鲁棒性强。     

A new sliding mode position controller with adaptive load torqueestimator for an induction motor

A new sliding mode control algorithm with an adaptive load torque estimator is presented to control the position of the induction motor in this paper. First, the rotor flux is estimated with the simplified rotor flux observer in the rotor reference frame and the feedback linearization theory is used to decouple the rotor position and the rotor flux amplitude. Then, a new sliding mode position controller with an adaptive load torque estimator is designed to control the position of the induction motor such that the chattering effects associated with the classical sliding mode position controller can be eliminated. Stability analysis is carried out using the Lyapunov stability theorem. Experimental results are presented to confirm the characteristics of the proposed approach. The good position tracking and load regulating responses can be obtained by the proposed position controller     

比例积分型线性超螺旋算法滑模观测器的感应电机无传感器控制

在无速度传感器感应电机调速系统中,针对滑模观测器存在滑模抖振与观测精度间的平衡问题,设计一种强鲁棒性的比例积分型线性超螺旋算法滑模观测器。首先,利用李雅普诺夫理论证明线性超螺旋算法的稳定性。然后,通过设计转子磁链观测器的中间变量,建立基于定子电流误差项的比例积分滑模面,构造出新的滑模磁链观测器。仿真与实验表明,该观测器有效抑制了滑模抖振,提升了电机的磁链观测与抗扰动能力,在电机运行时有较高的观测精度,提高了系统的动稳态性能。     

A fixed structure discrete-time sliding mode controller forinduction motor drives

In this paper, discrete-time sliding mode control is proposed for implementing an induction motor drive without varying the system structure. Very simple constant gain reaching control and sliding control are obtained to eliminate the chattering phenomenon and steady state error as well as to achieve robustness and minimized computation. For integration of the whole system, a simple field acceleration control algorithm is also derived to coordinate with the sliding mode control such that a simple 8 bit microcomputer can be used to implement a high performance induction motor drive     

有源电力滤波器神经终端滑模控制

以电力电子装备为接口的高渗透率可再生能源并网已成为未来配电网的显著特性。可再生能源具有随机性和间歇性,作为其并网接口的电力电子装备也会导致电能质量恶化等问题。为提高电能质量,该文提出一种有源电力滤波器神经终端滑模控制方法。首先,结合分数阶思想和滑模控制理论设计一种分数阶终端滑模控制器,以保证误差有限时间收敛,并引入边界层技术降低抖振。然后,利用自组织模糊神经网络构造一种无模型控制方案以更好地应对各种不确定因素。所设计的自组织模糊神经网络控制器用于学习分数阶终端滑模控制器,不仅从根源上解决抖振问题,而且可继承原控制器的有限时间收敛性能,并满足李雅普诺夫理论框架下的稳定控制性能。仿真与实验结果表明：所提出的控制方法能有效解决可再生能源发电系统中的谐波问题。     

Sliding mode controller for the single-phase grid-connected photovoltaic system

A sliding mode controller for the single-phase grid-connected photovoltaic system has been proposed in this paper. Contrary to the conventional controller, the proposed system consists of maximum power point tracker (MPPT) controller and sliding mode current controller only. The proposed MPPT controller generates current reference directly from the solar array power information and the current controller uses the sliding mode technique for the tight regulation of current. The new MPPT controller does not require the measurement of the voltage derivative which can be a cause of divide-by-zero singularity problems. The sliding mode controller has been constructed based on a time-varying sliding surface to control the sinusoidal inductor current and solar array power simultaneously. The proposed system can avoid the current overshoot and make optimal design for the system components. The structures of a proposed system are simple, but they show the robust tracking property against modeling uncertainties and parameter variations. The mathematical modeling is developed and the experimental results verify the validity of the proposed controller.     

Equivalent Sliding Mode Control Based On Nonlinear Observer For Nonlinear Non-Minimum-Phase Systems

A continuous sliding mode controller based on nonlinear robust observer for a class of nonlinear non-minimum-phase systems is presented, which utilizes synthetic output that is statically equivalent to the original process output and make the system minimum-phase. The designed continuous sliding mode controller can avoid chattering phenomenon. This work was partially supported by NSFC (National Natural Science Foundation of China) grant No. 60504005 to Xinhua Wang.     

Control of PEM fuel cell power system using sliding mode and super-twisting algorithms

Traditional sliding mode controller applied to a DC/DC boost converter for the improvement and optimization of the proton exchange membrane fuel cell (PEMFC) system efficiency, has the drawback of chattering phenomenon. Thus, based on the analysis of the mathematical model of PEMFC, this paper addresses the second order super twisting algorithm (STA) as a solution of chattering reduction, Stability of the closed loop system is analytically proved using Lyapunov approach for the proposed controller. The model and the controllers are implemented in the MATLAB and SIMULINK environment. A comparison of results indicates that the suggested approach has considerable advantages compared to the classical sliding mode control.     

Nonlinear controller design based on cascade adaptive sliding mode control for PEM fuel cell air supply systems

Optimized robust control for proton exchange membrane (PEM) fuel cell air supply systems is now a hot topic in improving the performance of oxygen excess ratio (OER) and the net power. In this paper, a cascade adaptive sliding mode control method is proposed to regulate oxygen excess ratio (OER) for proton exchange membrane (PEM) fuel cell air supply systems. Based on a simplified sixth-order nonlinear dynamic model, which takes parametric uncertainties, external disturbances and measurement noises into consideration, the nonlinear controller based on cascade adaptive sliding mode (NC-ASM) control is proposed. The method combines the nonlinear terms of super twisting algorithm and two added linear terms, and the modified second order sliding mode (SOSM) algorithm based on an observer is employed to form a cascade structure. Besides, an adaptive law is also utilized to regulate the parameters of the NC-ASM controller online. The performance of the controller is implemented on a real-time emulator. The results show that the proposed strategy performs better than the conventional constant sliding mode (CSM) control and PID method. Though during large range of load current and in the presence of various uncertainties, disturbances and noises, the NC-ASM controller can always converge rapidly, the feasibility and effectiveness are validated.     

基于交替单相PWM控制的三相光伏并网系统

提出了可用于多支路型三相光伏并网逆变器的交替单相PWM控制方法。该控制方法在一个工频周期内,逆变器有6种开关模式,每种开关模式中只须对三相中的一相桥臂进行PWM控制,从而有效降低了功率管开关损耗,在多支路光伏并网结构提高能量转换效率的基础上,进一步提高系统效率。采用电流滞环PWM跟踪控制,能够简单实现逆变正弦电流输出,跟踪性能好,并网功率因数为1,系统稳定性好,电流总谐波畸变率(THD)较低,可满足并网要求。通过Matlab仿真验证了该控制方法的正确性和有效性。     

基于自适应非奇异智能终端滑模观测器的风力机载荷增广预测控制

为有效降低风力机在高风速运行时的不平衡载荷,提出一种基于自适应非奇异智能终端滑模观测器的载荷增广预测控制策略。首先,针对模型不匹配导致的模型预测控制性能下降的问题,将指令跟踪误差与系统状态的变化量增广为状态向量,设计增广预测模型以消除稳态跟踪误差;其次,设计自适应非奇异终端滑模观测器对系统状态进行估计,以提高控制系统的可靠性;然后,设计多目标变速灰狼优化算法同时对控制器和观测器参数寻优;最后,基于Simulink仿真平台验证了所提控制策略的有效性。结果表明,所提控制策略可有效消除稳态误差,缩短调节时间并提高控制性能。     

Robust energy management strategy based on non-linear cascade control of fuel cells-super capacitors hybrid power system

The use of super capacitors as secondary sources in fuel cell power systems with adequate energy management strategy strongly contributes to increasing the lifespan of fuel cells by protecting them against sudden variations of the load current and improves the efficiency and the dynamics of the hybrid power system, thus obtained. This paper presents an innovative management strategy of fuel cells-super capacitors hybrid power system, based on a nonlinear control using an integral hysteresis sliding mode controller combined with two cascaded linear controllers. The hybrid power system consists of the fuel cells system, the super capacitors, two power converters, the energy management system and the load. The proposed technique takes into account the physical operating limits of the secondary source such as deep discharges and excessive overloads. Furthermore, the integral effect added to the hysteresis sliding mode controller improves the robustness against disturbances and variations in parameters such as filtering inductances and DC bus capacitors. A detailed model of the system is established and simulated in Matlab/Simulink software, which allows showing its behavior with a very satisfactory accuracy. The simulation results clearly show that the proposed control strategy insures efficient and safe energy transfer. In addition, the control robustness is very satisfactory despite the variation of the system parameters.     

Robust SVM-direct torque control of induction motor based on sliding mode controller and sliding mode observer

This paper proposes a design of control and estimation strategy for induction motor based on the variable structure approach. It describes a coupling of sliding mode direct torque control (DTC) with sliding mode flux and speed observer. This algorithm uses direct torque control basics and the sliding mode approach. A robust electromagnetic torque and flux controllers are designed to overcome the conventional SVM-DTC drawbacks and to ensure fast response and full reference tracking with desired dynamic behavior and low ripple level. The sliding mode controller is used to generate reference voltages in stationary frame and give them to the controlled motor after modulation by a space vector modulation (SVM) inverter. The second aim of this paper is to design a sliding mode speed/flux observer which can improve the control performances by using a sensorless algorithm to get an accurate estimation, and consequently, increase the reliability of the system and decrease the cost of using sensors. The effectiveness of the whole composed control algorithm is investigated in different robustness tests with simulation using Matlab/Simulink and verified by real time experimental implementation based on dS pace 1104 board.     

Robust maximum power point tracker using sliding mode controller for the three-phase grid-connected photovoltaic system

A robust maximum power point tracker (MPPT) using sliding mode controller for the three-phase grid-connected photovoltaic system has been proposed in this paper. Contrary to the previous controller, the proposed system consists of MPPT controller and current controller for tight regulation of the current. The proposed MPPT controller generates current reference directly from the solar array power information and the current controller uses the integral sliding mode for the tight control of current. The proposed system can prevent the current overshoot and provide optimal design for the system components. The structure of the proposed system is simple, and it shows robust tracking property against modeling uncertainties and parameter variations. Mathematical modeling is developed and the experimental results verify the validity of the proposed controller.     

Position Control of Induction and DC Servomotors: A Novel Adaptive Fuzzy PI Sliding Mode Control

A position control of a class of servomotors is addressed in this paper via a novel adaptive fuzzy PI sliding mode control. The premise and the consequence parts of the fuzzy rules are tuned with adaptive schemes. To attenuate chattering effectively, the discontinuous control is approximated by an adaptive PI control structure. Moreover, the bound of the discontinuous control term is assumed to be unknown, and an adaptive mechanism is used to estimate this bound. All adaptive laws are derived via Lyapunov synthesis method, thereby guaranteeing the closed-loop stability. The proposed approach has the added advantage that, for external disturbances, it only requires a bound to exist, without needing to know the magnitude of this bound. The proposed controller is applied to control a model of uncertain induction servomotor subject to significant disturbances and a model of DC servomotor with unknown parameters and uncertainty in load condition. The analysis of simulations reveals the effectiveness of the proposed method in controlling servomotors in terms of significant reduction in chattering while maintaining asymptotic convergence.     

基于转速估计的PMSM分数阶积分滑模控制

针对永磁同步电机(PMSM)运行过程中内部参数变化和外部负载扰动影响控制性能的问题,采用基于分数阶滑模观测器的PMSM分数阶积分滑模控制(FOISMC)策略。基于FOISMC技术,设计基于新型趋近律的分数阶积分滑模转速调节器,给出能保证系统全局鲁棒性的全程积分滑模面设计方法。基于分数阶理论和滑模控制理论构造分数阶滑模观测器,以实现对速度和转子位置角的高精度估计。仿真实验验证了所提方法的可行性和有效性。     

Control of a solid oxide fuel cell stack based on unmodeled dynamic compensations

To guarantee solid oxide fuel cell (SOFC) safe operation, plenty control strategies have been developed to control stack temperature and voltage within a reasonable range. However, these control approaches ignore unmodeled dynamics of the SOFC system, which may lead to unsatisfactory control results, sometimes even make the system unstable. To overcome this challenge, a unique control strategy which considers unmodeled dynamic compensations of the SOFC system is proposed in this paper. A model of the SOFC system is firstly built, which includes a known linear model and an unmodeled nonlinear dynamic estimation. A nonlinear controller based on the unmodeled dynamic compensation is then developed to force the SOFC to track desired stack temperature and voltage. To evaluate the control performance, the proposed control method is compared with a traditional sliding mode controller. The simulation results show if the unmodeled dynamics have a small effect on the SOFC, both the sliding mode controller and the proposed controller can achieve a precise tracking. If the unmodeled dynamics have a great impact on the SOFC, the temperature and voltage can be well controlled with the proposed control strategy. However, in the sliding mode controller, the temperature and voltage trajectories deviate largely from the reference values.