Evaluation of a digital control system for a high-efficiency battery charger/UPS

Recently, the Plant Input Mapping (PIM) method was proposed as a digital-redesign (or an emulation) approach in digital control system design. This method guarantees stability of a redesigned digital control system for a wide range of sampling periods. In this paper the PIM method is applied to the design of a digital model-matching flight control system. In the model-matching control system design a plant must have no unstable zeros. However, unstable zeros appear for small sampling periods in a step invariance model of a continuous-time (CT) plant with the relative degree greater than two, even if the CT plant has no unstable zeros. Hence, in such a case, the direct-digital approach cannot be applied to the design of a digital model-matching control system. By contrast, the digital-redesign approach such as the Tustin's method or the PIM method is free from the problem. Simulation results for an unstable VTOL aircraft show that the proposed method gives better performance than the conventional design methods.

The insertion of communication networks in closed-loop of digital control systems makes the system synthesis and analysis complex. In this paper, we consider the combination of classical reliability, risk and safety evaluation with typical control system through digital networked control systems. The main purpose is to study the influence of transmission delays and packet dropouts on the reliability of digital networked control systems by using a modified statistical method-Monte Carlo simulation. The behaviors of two types of fault are modelled by different statistical distribution. The control strategies we apply for digital control systems are Proportion Integration Differentiation control strategies, generated by Genetic Algorithm. In terms of a realistic system model, we evaluate and compare the influences on the reliability of digital networked control systems with different control strategies from quantitative aspect. Numerical examples are presented to illustrate the effectiveness and correctness of the approach.

This study presents a linear matrix inequality (LMI) approach to the sampled-data control of Takagi-Sugeno fuzzy systems, based on the intelligent digital redesign (IDR) technique. The objective of the IDR is to design a digital control system whose trajectory closely matches that of a given well-constructed analogue control system by minimising the state-matching error. In this study, state-matching performance is enhanced by using a continuous-time state-matching criterion, which guarantees that the state-matching error is minimised through the entire time interval. Unlike previous studies, mismatched information of membership functions for both analogue and digital control systems is directly manipulated. Moreover, the authors introduce an improved fuzzy Lyapunov functional that consists of both membership functions for analogue and digital control systems, which relaxes the conservativeness of LMI conditions. Finally, two examples demonstrating the effectiveness of the authors' method are provided.

Neste artigo, é proposta a utilização de um único circuito de auxílio à comutação ZVT, aplicado tanto no estágio pré-regulador como no carregador de baterias de Sistemas Ininterruptos de Energia (UPS). Também, é demonstrado que a utilização de uma única célula de comutação ZVT permite que se obtenha, além da redução do número de componentes auxiliares, um melhoria no rendimento do conversor. Adicionalmente, duas estratégias de controle, digital e analógica, são analisadas e comparadas do ponto de vista de desempenho e custo. O sistema de controle analógico é implementado com vários CI’s dedicados, já o controlador digital é implementado por meio de um único DSP de baixo custo. Um protótipo em malha fechada de 580 W, com entrada universal, operando em 100 kHz, foi implementado nã só para validar o circuito de auxílio à comutação, mas também para avaliar o desempenho do sistema proposto.

DC-DC converters are used at the Advanced Photon Source (APS) at Argonne National Laboratory to power electromagnets. The electromagnets guide the photon beams, therefore the control system of the DC-DC converters should be highly accurate to provide minimum spatial spread of the beam. Currently the converters have all been regulated by analog control systems. An upgrade to digital control system is being evaluated to resolve the aging and obsolescence issues. This paper describes the design and evaluation of a digital control system to regulate the output current and reduce noise coupled in the system. A digital controller is first designed based on the small signal model of the converter. Experimental data of the output current is analyzed. Digital filters are then designed to reduce the noise in the output current. The complete control system is then simulated and results are evaluated. Wide Band Gap (WBG) power devices enable the development of smaller and more durable power converters with higher performance and less power consumptions than traditional silicon devices. Performance of the digital controlled DC-DC converters using WBG power switching devices including silicon carbide (SiC) power MOSFETs and gallium nitride (GaN) power transistorswill be evaluated, in comparison with the converters using traditional silicon power switching devices.

The DC-DC converters at the Advanced Photo Source at Argonne National Laboratory are over 15 years old. An upgrade to digital control system is being evaluated to resolve the aging and obsolescence issues. These converters supply power to electromagnets that are used to guide high energy beams. Thus a highly accurate control system is required for the DC-DC converters. This paper describes the design and evaluation of a digital control system to regulate the output current. The digital control system is proposed to replace the current analog control system thereby resolving the aging and obsolescence issues. A digital controller is first designed based on the small signal model of the converter. Experimental data of the output current is analyzed. The complete control system is then simulated and results are evaluated.

This paper focus on the digital control system for bearingless permanent magnet rotor motors. The bearingless permanent magnet synchronous motor (BPMSM) is an innovational type of motor, as bearingless motors have all advantages of magnetic bearings, they play an important role in solving difficult problems of special electric drives in life science, chemical processing industry, semiconductor manufacturing industry, foodstuff processing industry, and so on. In the paper, based on the basic working principle of BPMSM, the mathematics models of the radial forces and rotation part on BPMSM are deduced by adopting rotor magnetic field oriented control (FOC) strategy. A digital vector control system according to the demand of decoupling is designed and presented using DSP technique. An experimental platform of digital control system is developed to meet the need, The experiment results have shown that the steady suspension of the rotor is realized and the speed of the rotor can be continuously adjusted within the range of 0-3000 r/min.

A series of structural vibration control experiments and related theory are developed to check the effectiveness of analog and digital control system with piezoelectric material sensors and actuators. Velocity feedback analog control has been tried for the cantilever beam with PZT (lead-zirconate-titanate) wafer sensors and actuators. To improve the control system, steady- state quadratic optimal control algorithm using a digital micro-computer has been used. To apply optimal control algorithms, signals sensed by partially distributed sensors were converted to point concept signals like those from conventional displacement or velocity sensors. Actuating voltage signals were then synthesized from point force output signals. This paper presents excellent results for structural vibration control using both analog and digital systems.

A digital closed-loop control system with all digital phase locked loop (ADPLL) is designed and optimized, in order to improve the bias stability and transient response of the gyroscope. The nonlinear mathematical models for the closed-loop amplitude and phase control system are established. The linearization method is applied to analyze the nonlinear models. The control parameters of the drive loop are optimized. The experimental results show that the phase deviation between the demodulation reference signal of the drive loop and the sense signal is less than 0.25° in the temperature range from-40°C to 60°C, within 0.15° of the variation. At room temperature, the overshoot amount of the gyroscope control system is 4.5% with setting time of 0.12s. The bias stability is 1.45°h. Compared to the analog control scheme, the digital control system has advantages of short setting time, small overshoot, short phase locked time, large locked range, high phase precision, etc.

The article discusses an approach that allows you to move from a discrete model of a digital controller to its analog representation, which provides analysis and synthesis of digital systems in the continuous domain, taking into account the quantization period. In the proposed method for the control system, a transition is made from the discrete z-region to the Laplace region. This approach makes it possible to consider the quantization time as an additional parameter of the digital control system settings, evaluate the influence of the selected quantization period not only on the behavior of the set for discrete at the moments of quantization, but also in between, to evaluate the temporal characteristics of the control system at any time. The analog representation of the digital controller enables the calculation of transients using MatLAB. The article provides examples of the synthesis for a digital control system in the frequency domain based on the frequency response characteristic of an open-loop control system taking into account the quantization period. The method can be used by automation specialists to analyze and setting digital control systems

A digital control system has been developed to control the frequency of an alternator operating at variable speeds. The power line frequency or a crystal controlled oscillator can be used as the reference frequency. The alternator output has a ±0.2 percent tolerance to the reference signal after the frequency control system was added. The frequency control of the alternator was accomplished by switching windings in the alternator field. The method is applicable to wind-powered alternators where the speed is variable and a constant 60 Hz output is desired.

Beginning with process controls in the mid fifties, digital control systems have seldom met all the claimed advantages and in many cases have been outright failures. Airborne digital computers have just begun to appear in the commercial jet transport market after several years of experimental and military development. The success of these systems in meeting user expectations has not been overwhelming, which leads to the question: Why change from known analog flight control technology to digital? This paper examines that question by reviewing the state of the art in analog flight control system technology and evaluating this against current airline problems. A realistic means of evaluating claimed advantages for new technology is thus established. The advertised solutions of digital technology to analog problems are examined and, in some cases, debunked. However, consideration of the real problems and the capabilities of digital systems leads to the conclusion that there is a real payoff. Evidence from background studies at Boeing is offered to support this conclusion. A description of the digital flight control system electronics (FCSE) development program for the new Boeing 7×7 airplane is also provided. This program is currently in progress, and its specific objective is to assure that the real payoff is achieved for the subsequent production system.

The digital control system of modular multilevel converters (MMCs) normally synchronizes with the switching actions. The switching frequency of an MMC is generally selected as low as possible from an efficiency point of view, which leads to an unavoidable and relatively long time delay in the control system. Such a time delay might deteriorate the MMC performance and even reduce the stability margin by introducing infinite uncertain eigenvalues into the system state functions. Without a proper time-delay model and quantitative system stability analyses, MMCs might suffer from uncertainties and unstable risks during their operations, especially when the switching frequency is low. This paper derives an MMC model considering the time delay in the digital control system. A Pade-based stability analysis method is then proposed, which consists of three steps: information integration and critical eigenvalue extraction, and trajectory visualization and critical angle (CA) calculation, and quantitative assessment and extreme value determination. By the proposed model and method, the critical eigenvalue can be effectively extracted. With the Hopf bifurcation, the time delay in the digital control system induces a pair critical conjugate eigenvalues into MMC systems, which is detected as an instability cause. The CA and the critical impact are defined to quantitatively assess the stability, while selecting the controller parameters and minimum switching frequency. The proposed method for the MMC stability assessment is experimentally verified.

A digital control system is probably the best technical solution to the problem of automatic control of the Virgo interferometric antenna for gravitational wave detection, provided that very critical specifications concerning residual noise introduced by the digital system in the measurement band are met. For this purpose, a model of the digital system has been developed and tested to quantify the main sources and levels of noise. Experimental measurements, obtained using a prototype of the automatic control system, and theoretical analysis of the performances of the digital control loops have demonstrated the feasibility of a digital control system.

The paper presents the analysis on stability of digital control system for unmanned vehicle with numerical analysis. The objective of this study is mainly emphasized on the fulfillment of the advanced control techniques according to the fundamental concepts of digital control system approaches for unmanned aerial vehicle system design. The targeted unmanned aerial vehicle system was designed based on the simple construction under the idea of fixed wing flight system approaches. The stability analyses on unmanned aerial vehicle are vital role to enhance the real world applications. The background concepts on digital control system for stability analysis on dynamic control system like unmanned aerial vehicle system. The appropriate controller design for dynamic control system of unmanned aerial vehicle is vital role to analyze the accurate stability condition for reality. The implementation of numerical analysis on compensator design has been developed by using MATLAB. The physical parameters in these analyses are based on the experimental outcomes from the recent research works in dynamical system implementations. The mathematical approaches are very helpful for numerical analysis on compensator design for the unmanned aerial vehicles schemes. The simulation results confirm that the high performance stability test on unmanned aerial vehicle system has been met with the theoretical works.