西门子6SE70系列变频器的控制模式及其应用

在冶金生产中,各种生产设备有着不同的工况。根据不同的工况,变频器应当设置相应的控制模式,主要包括V／f控制、矢量控制、转矩控制等模式,以满足实际生产的需求。根据笔者在设计、开发工作中积累的经验,本文扼要地介绍了采用变频器控制传动设备时,针对传动系统的不同工况和不同要求,选用合适的变频器工作模式的相关思路,同时也提出了实际设计工作中必须注意的诸多技术问题。     

Multi-model unfalsified adaptive switching supervisory control

The paper studies how on-line inferring stability of a potential control-loop consisting of an uncertain plant interconnected in feedback with a candidate controller using plant I/O pairs recorded while the plant is possibly driven by a different controller. In such a context, a convenient tool to work with is to resort to the conceptual entity of a virtual reference (VR). The adopted approach consists of embedding, in the so-called unfalsified adaptive switching control schemes based on VR, a family of nominal models pairwise associated with the given candidate controllers. The result is that the supervised switching mechanism can moderate the chance that destabilizing controllers be switched-on and, hence, reduce both the magnitude and time durations of “learning” transients after start-up, while, in contrast with pre-existing multi-model based methods, stability in-the-large is guaranteed under the minimal conceivable assumption that a stabilizing candidate controller exist.     

Modal and transition dwell time computation in switching systems: A set-theoretic approach

We consider a plant the dynamics of which switch among a family of systems. Each of these systems has a single stable equilibrium point. We assume that a constraint region for the state is assigned and we consider the problem of finding suitable limitations on the commutation speed in order to avoid constraints violations, even in the absence of state measurements. We introduce the concepts of modal and transition dwell times which lead to the definition of dwell time vector and dwell time graph (represented by a proper matrix), respectively. The former imposes a minimum permanence time on a discrete mode before commuting, the latter imposes the minimum permanence time on the current mode before switching to a specific new one. Both dwell time vector and dwell time graph can be computed via set-theoretic techniques. When the systems share a single equilibrium state, stability can be assured as a special case. Finally, under the assumption of affine dynamics, non-conservative values are achieved.     

The strategic choice to continue outsourcing,switch vendors,or backsource: Do switching costs matter?

IT outsourcing contracts are often discontinued in favor of other alternatives (returning to in-house development, or switching to another vendor). Switching costs are experienced when terminating a business relationship and securing an alternative. We tried to answer the question: do switching costs matter significantly in the strategic choice to continue outsourcing, switch vendors, or backsource? Switching costs were considered, such as those due to IT operations (sunk investment, lost performance, system upgrades, uncertainty, and induction–retraining–performance), personnel-replacement costs (candidate search, and IT/setup), and in-house learning (cognitive/behavioral learning). A field survey was conducted, and, for each of these cost types, the differences between group means across the three groups (outsourcing continuation, vendor switching, and backsourcing) were determined. The findings suggested that customer organizations preferred outsourcing continuation most and backsourcing least when their switching costs were high. However, the relative preference for vendor switching depended on the switching cost type.     

基于微处理器和PWM的船用大功率直流电机起动与调速研究

采用PWM脉宽调制改变直流电压的控制方式,具有效率高、电压连续可调等优点,已广泛应用于大功率直流电机的调速中。本文对直流电动机调速驱动方式中存在的问题进行了分析,应用微处理器对驱动模块进行适时检测与自动切换,保证驱动系统的工作连续性和安全稳定性;对操作人员非正常操作或误动作产生的错误指令给以合理的修正,提高系统的操作客...     

基于TIADC的信号采集记录卡

目前的信号采集系统的采样和实时记录速率只有每秒几十兆,远不能满足对信号进行实时、连续、高速、高精度采集记录的需求。针对该问题,设计并实现一种基于时间交错模数转换器的信号采集记录卡,可以实现14位200 MS/s的数据采集,有效的无杂散动态范围超过80 dBc,可实现400 MB/s持续实时的数据记录。     

Moving horizon estimation for switching nonlinear systems

This paper is concerned with moving horizon estimation for a class of constrained switching nonlinear systems, where the system mode is regarded as an unknown discrete state to be estimated together with the continuous state. In this work, we establish the observability framework of switching nonlinear systems by proposing a series of concepts about observability and analyzing the properties of such concepts. By fully applying the observability properties, we prove the stability of the proposed moving horizon estimators. Simulation results are reported to verify the derived results.