无刷双馈电机控制与应用前景

无刷双馈电机(BDFM)是一种新型交流电机,它兼有异步电机和同步电机的共同优点,去掉了转子侧电刷,提高了机械稳定性,降低了维修成本。本文详细综述了无刷双馈电机的发展历史、运行原理、数学模型、控制策略,简单介绍了无刷双馈电机的应用,并对其发展前景作了展望。     

An approach for handling the nonlinearities of HVDC system forstability analysis

An approach for linearizing the nonlinearities of the high voltage direct current (HVDC) system for analyzing the system stability over wide range of operation is presented. The nonlinearities can be linearized with ±5% error over a wide range of system operation. It is shown that the nonlinearities introduced by the converter, real power, and reactive power equations can be linearized over a wide range by using the integral square error (ISE) method. The results are compared with standard techniques called small signal analysis. It is shown that the stability margin of the system predicted by the new technique is relatively smaller than what is predicted by small signal analysis. The system stability boundaries are determined by the AC voltage and the reactive current control. These two control schemes may provide the same stability margin, provided appropriate controller gains are selected. The power factor control modeling is discussed     

平流层飞艇特征结构配置增稳设计

对飞艇非线性六自由度模型进行线性化,得到了飞艇的状态方程,并将其分为纵向和侧向两组.以飞艇非线性模型为基础对飞艇自然特性进行了分析,对飞艇的纵向运动及侧向运动的稳定性进行了分析仿真.运用基于线性矩阵不等式（LMI）的特征结构配置方法对平流层飞艇进行增稳控制律设计,不仅实现了特征值的配置,同时确定闭环系统特征值对应的特征向量和广义特征向量.     

Experimental evaluation of a rotor flux oriented control algorithmfor brushless doubly-fed machines

The brushless doubly-fed machine (BDFM) has shown potential for adjustable speed drive applications. Although the BDFM is readily applicable for industrial drives requiring only slow speed response, control methods for higher performance operation need to be explored. With the help of a suitable synchronous reference frame dq model, this paper defines a BDFM synchronous angle and employs an electric torque estimator to establish a rotor flux oriented control algorithm. Experimental results show the effectiveness of the proposed controller     

A new computer-aided approach to the analysis of CuK converter byusing the alternator equations

A novel approach to the computation of the transient and steady-state response of power electronic switching converters is presented. The solution exhibits precision and reflects the continuous character of the converter waveforms. The key to the approach is the extraction of the switching elements (transistors, or transistor and diode, operated as synchronous switches) in a time-varying two-port called an alternator. The remaining part of the converter is linear and time-invariant; it can be described, in the complex frequency domain, by a system of modified nodal equations. The constitutive equations of the alternator are added, providing a global model of the cyclically switching circuit in the s-domain. The converter is analyzed using the Laplace transform. The modified nodal equations of the converter are solved, and the inverse Laplace transform of their solutions is found. The time-domain solutions together with boundary conditions for cyclical operation of the converter are used for the computer-aided calculation of the transient and steady-state response. The method is applied to a coupled-inductor Cuk converter operating in a continuous conduction mode in which the transient state is due to a step-in-line input voltage     

A passivity-based method for induction motor control

The control of an induction motor is a difficult problem, since the dynamics of the induction motor are nonlinear, the rotor electrical state variables (i.e., rotor fluxes or currents) are usually unavailable for measurement, and the motor parameters can vary significantly from their nominal values. The main purpose of this paper is to develop a control algorithm that forces the induction motor to track time-varying speed, position, and flux trajectories without knowledge of the rotor electrical state variables. To achieve this, a passivity-based method is developed. The key point with this method is the identification of terms, known as workless forces, which appear in the dynamic equations of the induction motor but do not have any effect on the energy balance equation of the induction motor. These terms do not influence the stability properties of the induction motor and, hence, there is no need to cancel them with feedback control. This leads to a simpler control structure and enhances the robustness of the control system. Experimental results show that the passivity-based method provides close tracking of time-varying speed, position, and flux trajectories without knowledge of the rotor electrical state variables     

A discrete time domain modeling and analysis of controlled seriesresonant converter

A discrete time domain modeling and analysis technique applicable to all types of inner-feedback and noninner-feedback-controlled series resonant converter (SRC) is presented. The nonlinear discrete time domain equations representing the static and dynamic behavior of the SRC are derived and linearized about the equilibrium state of the SRC. In addition, the inner-feedback control law is linearized about the equilibrium state. The linearized SRC and the linearized inner-feedback control law are then combined to arrive at a linearized inner-feedback-controlled SRC. The linearized modeling is used to analyze the stability and dynamic characteristics of the controlled SRC     

Matrix methods for the study of a regulated synchronous machine

A powerful but simple matrix method for the digital computer manipulation of large sets of differential and algebraic equations is introduced to the field of power systems. The method is first illustrated with reference to the linearized equations representing a general-purpose turboalternator model. Subsequently, the form of the system equations obtained as a result of the matrix method is seen to provide a unified approach to the determination of system stability limits using Routh, Nyquist, or eigenvalue methods. The normal state space form of the system equations is also shown to facilitate control studies. A previously suggested performance criterion for an excitation system is generalized, and a systematic method for the simultaneous optimization of governor and exciter control loops is suggested. This method of optimization does not require the evaluation of system transient responses. The manner in which the normal state space form of the system equations leads naturally to the synthesis of controllers which are optimal with respect to a chosen scalar quadratic performance index is indicated. With this form of control, the structure is not defined a priori but emerges from the computational algorithm and it becomes unnecessary to specify the source or the magnitude of the stabilizing signals required to provide an improved dynamic performance. Finally, the matrix method is shown to be effective for the manipulation of the nonlinear machine equations and these are obtained in a new form which is directly amenable to digital or analog computer solution.     

Driver Deadtime Control and Its Impact on System Stability of Synchronous Buck Voltage Regulator

Driver dead-time control is a popular scheme used to prevent the occurrence of the shoot-through issue in a synchronous Buck voltage regulator. As the switching frequency is continually increasing in today's converter design, the deadtime interval is now long enough relative to the switching period to impact the system performance. In addition to its impact on efficiency, driver dead-time also impacts loop gain and system stability, especially under the critical load condition. In this paper, the influence of driver dead time on the synchronous buck converter is investigated in detail. With voltage mode control, the system loop gain will change under different load conditions due to the deadtime impact. The deadtime may cause sub-harmonic current ripple in the voltage regulator with sample-and-hold current mode control, while its impact on the peak current mode control can be ignored. Design equations are provided to avoid this issue. Some analysis data are included and compared to experimental results.     

A novel overmodulation technique for space-vector PWM inverters

In this paper, a novel overmodulation technique for space-vector pulsewidth modulation (PWM) inverters is proposed. The overmodulation range is divided into two modes depending on the modulation index (MI). In mode I, the reference angles are derived from the Fourier series expansion of the reference voltage which corresponds to the MI. In mode II, the holding angles are also derived in the same way. The strategy, which is easier to understand graphically, produces a linear relationship between the output voltage and the MI up to six-step operation. The relationship between those angles and the MI can be written in lookup tables or, for real-time implementation, can be piecewise linearized. In addition, harmonic components and total harmonic distortion (THD) of the output voltage are analyzed. When the method is applied to the V/f control of an induction motor, a smooth operation during transition from the linear control range to the six-step mode is demonstrated through experimental results     

Network calculations for power system stability studies using bus admittance matrix

Network calculations can be made to account for frequency dependance on network elements. The method utilizes a current source model for synchronous machines. Since use is made of the sparse bus admittance matrix of the network, the method is suitable for large-scale power system stability studies.     

Small-signal behavior of nonlinear lumped networks

This paper develops two theorems concerning the small-signal behavior of nonlinear time-varying networks whose state equations are of the form x^·= f(x, u, t). The conclusions of the theorems are supported by experiments. The input is of the form U(t) + u(t), where the bias U(t) is allowed to be time-varying (typically, slowly varying) and u(t) is the small signal. The bias induces a moving operation point X(t). Given some simple assumptions concerning the linearized small-signal equivalent circuit it is shown that provided u(t) is sufficiently small on [0, ∞), the state trajectory about the operating point is bounded on [0, ∞) and tends to zero as u → 0. The method of proof also shows that this result applies to some distributed circuits. The second theorem shows that the push-pull connection reduces the distortion due to the nonlinearities of both resistors and energy storing elements. The third part of the paper describes numerical experiments that support the conclusions of the theory and a design procedure for nonlinear networks to be operated in the small-signal mode.     

Stability and Constrained Control of a Class of Discrete-Time Fuzzy Positive Systems with Time-Varying Delays

This paper deals with the stability of nonlinear discrete-time positive systems with time-varying delays represented by the Takagi–Sugeno (T–S) fuzzy model. The time-varying delays in the systems can be unbounded. Sufficient conditions of stability which are not relevant to the magnitude of delays are derived by a solution trajectory. Based on the stability results, the problems of controller design via the parallel distributed compensation (PDC) scheme are solved. The control is under the positivity constraint, which means that the resulting closed-loop systems are not only stable, but also positive. Constrained control is also considered, further requiring that the state trajectory of the closed-loop system be bounded by a prescribed boundary if the initial condition is bounded by the same boundary. The stability results and control laws are formulated as linear matrix inequalities (LMIs) and linear programs (LPs). A numerical example and a real plant are studied to demonstrate the application of the proposed methods.     

FunState-an internal design representation for codesign

In this paper, an internal design model called FunState (functions driven by state machines) is presented that enables the representation of different types of system components and scheduling mechanisms using a mixture of functional programming and state machines. It is shown how properties relevant for scheduling and verification of specification models such as Boolean dataflow, cyclostatic dataflow, synchronous dataflow, marked graphs, and communicating state machines as well as Petri nets can be represented in the FunState model of computation. Examples of methods suited for FunState are described, such as scheduling and verification. They are based on the representation of the model's state transitions in the form of a periodic graph. The feasibility of the novel approach is shown with an asynchronous transfer mode switch example     

Model reference adaptive control (MRAC)-based parameter identification applied to surface-mounted permanent magnet synchronous motor

In this work, a model reference adaptive control-based estimated algorithm is proposed for online multi-parameter identification of surface-mounted permanent magnet synchronous machines. By taking the dq-axis equations of a practical motor as the reference model and the dq-axis estimation equations as the adjustable model, a standard model-reference-adaptive-system-based estimator was established. Additionally, the Popov hyperstability principle was used in the design of the adaptive law to guarantee accurate convergence. In order to reduce the oscillation of identification result, this work introduces a first-order low-pass digital filter to improve precision regarding the parameter estimation. The proposed scheme was then applied to an SPM synchronous motor control system without any additional circuits and implemented using a DSP TMS320LF2812. For analysis, the experimental results reveal the effectiveness of the proposed method.     

A nonlinear speed control for a PM synchronous motor using a simpledisturbance estimation technique

A nonlinear speed control for a permanent-magnet (PM) synchronous motor using a simple disturbance estimation technique is presented. By using a feedback linearization scheme, the nonlinear motor model can be linearized in the Brunovski canonical form, and the speed controller can be easily designed based on the linearized model. This technique, however, gives an undesirable output performance under the mismatch of the system parameters and load conditions. An adaptive linearization technique and a sliding-mode control technique have been reported. Although good performance can be obtained, the controller designs are quite complex. To overcome this drawback, the controller parameters are estimated by using a disturbance observer theory where the disturbance torque and flux linkage are estimated. Since only the two reduced-order observers are used for the parameter estimation, the observer designs are considerably simple and the computational load of the controller for parameter estimation is negligibly small. The nonlinear disturbances caused by the incomplete linearization can be effectively compensated by using this control scheme. Thus, a desired dynamic performance and a zero steady-state error can be obtained. The proposed control scheme is implemented on a PM synchronous motor using a digital signal processor (TMS320C31) and the effectiveness is verified through the comparative simulations and experiments     

Global Synchronization and State Tuning in Asymmetric Complex Dynamical Networks

A strategy to control the complex dynamical networks for global synchronization as well as to tune their synchronous states is presented based on linear state feedback controllers. The synchronous state can be changed from one system to other similar system just by choosing a suitable tuning matrix. Especially, some of the criteria are expressed in normal inequalities instead of matrix inequalities. Simulations are also done to verify the theoretical results.      

开关电源电路控制过程的动态仿真

采用Matlab对开关电源的控制模式进行了仿真分析。采用离散分析方法，对于用解析方式无法求解的状态方程进行了离散处理，分析了开关电源系统的动态性能，包括负载突变、输入特性分析以及系统从初态到稳态的建立过程。阐明了仿真程序的编制方法及该仿真方式的特点。并充分利用Matlab强大的计算功能，运用矩阵运算编制程序．使程序流程更加简明。     

Spectral factorization of time-varying covariance functions

The determination of the state-space equations of a time-varying finite-dimensional linear system with a prescribed output covariance matrix is considered when the system is excited by Gaussian white-noise inputs. It is shown that a symmetric state covariance matrix provides the key link between the state-space equations of a system and the system output covariance matrix. Furthermore, such a matrix satisfies a linear matrix differential equation if the state-space equations of the system are known, and a matrix Riccati equation if the output covariance matrix of the system is given. Existence results are given for the Riccati equation solution, and discussion of asymptotic solutions of the differential equations is also included.     

Robust Stabilization Analysis for Uncertain Systems with Time-Varying Delays

Many techniques have been proposed to stabilize uncertain systems with state delay via state feedback in Ref.[1~12], LI et al. investigated the approach of linear matrix inequality (LMI) [1,5], Mori, Su et al. discussed the robust stabilization where the uncertainty satisfies the so-called matching conditions, by using the property of LMI[2,3]. Perterson et al. introduced a Ricatti equation approach[6], Hoi, Shen et al., designed the state feedback controller to stabilize the uncertain dy…