J. Jugo

Stability verification of microwave circuits through Floquet multiplier analysis

This work presents a procedure to verify the stability of periodic regimes of microwave circuits that are simulated with harmonic-balance algorithms. The technique is based on computing the Floquet multipliers associated to the system linearization around the periodic regime. The proposed procedure has been applied to a C-band GaAs prescaler. Stability analysis results provide an estimation of the circuit input sensitivity curve that is in good agreement with measurement results.

Analysis and elimination of parametric oscillations in monolithic power amplifiers

This work describes an analysis and design methodology for eliminating parametric oscillations in microwave power amplifiers. Large-signal stability analyses based on system pole-zero identification techniques are proposed to guide the design process towards a stable circuit. In order to demonstrate the proposed approach, parametric oscillations of a Ku-band MMIC power amplifier have been eliminated, while maintaining the original performances of the circuit.

DISCRETIZATION OF CONTINUOUS TIME-DELAY SYSTEMS

Abstract Many works are related to the analysis and control of either continuous or else discrete time-delay systems. However, the discretization of continuous time-delay systems has not been extensively studied. In this work, sampled-data time-delay systems with internal and external point delays are described by approximate discrete time-delay systems in the discrete domain. Those approximate discrete systems allow the hybrid control of time-delay systems. Several examples complete the paper, showing the correctness of the discretization process.

ESS-Bilbao light-ion linear accelerator and neutron source: design and applications

The baseline design for the ESS-Bilbao light-ion linear accelerator and neutron source has been completed and the normal conducting section of the linac is at present under construction. The machine has been designed to be compliant with ESS specifications following the international guidelines of such project as described in Ref. [1]. The new accelerator facility in Bilbao will serve as a base for support of activities on accelerator physics carried out in Spain and southern Europe in the frame of different ongoing international collaborations. Also, a number of applications have been envisaged in the new Bilbao facility for the outgoing light ion beams as well as from fast neutrons produced by low-energy neutron-capture targets, which are briefly described.

Stability analysis and robust control design on an AMB system

This paper describes a stability analysis and a Hinfin robust control design for an electromechanical system consisting of a rotary flexible spindle hovered by active magnetic bearings (AMB), whose potential uses in the machine-tool industry have been well documented. Firstly, a complete experimental stability analysis is performed controlled by a previously designed PID controller. This is performed via the ISO 14839-3 standard, which reliability needs to probe the negligibility of some effects. Then, since the lack of robustness is concluded by the previous study, an Hinfin control design is accomplished. Moreover, the ill-conditioning of the matrices when the DGKF algorithms are solved, is avoided performing a model reduction. This is carried out by means of the symmetry properties which characterize the system and hence, facilitating the design. The better behavior of the system is probed by simulation in a complete model of the real device.

Analysis and control design of MIMO systems based on symmetry properties

In this work the design advantages derived from certain symmetry properties inherent to different class of systems are explored. In particular, some class of MIMO systems which can be separated into different and independent SISO problems, thus making easier the analysis and control design, are addressed. Also, it is shown how the symmetry properties give a direct way for open-loop identification, valid also in unstable cases, using closed-loop data. As a real-world application example, the proposed method is applied to a magnetic bearing system having the required symmetry properties.

2-DOF Controller Design for Precise Positioning a Spindle Levitated with Active Magnetic Bearings

This article describes the design of a high performance 2-DOF controller for an electromechanical system consisting of a rotary flexible spindle hovered by Active Magnetic Bearings (AMB). The purpose of such a controller is to achieve the better positioning possible of the spindle by means of a good stabilization mechanism and by counteracting the vibrations generated naturally by the rotation. The implementation of this controller is based on three main blocks, a stabilization block, a vibration minimization block and, if needed, a dynamics decoupler block between the previous ones. The stabilization controller is designed utilizing a MIMO decoupling technique. With the aim of proving its effectiveness, two different stabilization controllers (PID and H ∞ ) are presented. On the other hand, an adaptive feedforward algorithm which is in charge of the vibration minimization is implemented. In order to not feedback the vibration and, therefore, to decouple the controllers dynamics, the implementation of a variable Notch filter is discussed. It is demonstrated that this optional block can enhance or impoverish the behavior of the system depending on several factors such as resonances or rotational speed measurement. Experimental results and simulations are provided to show the effectiveness of the complete design process.

ISHN Ion Source Control System. First Steps Toward an EPICS Based ESS-Bilbao Accelerator Control System

ISHN (Ion Source Hydrogen Negative) consists of a Penning type ion source in operation at ESS-Bilbao facilities. From the control point of view, this source is representative of the first steps and decisions taken towards the general control architecture of the whole accelerator to be built. The ISHN main control system is based on a PXI architecture, under a real-time controller which is programmed using LabVIEW. This system, with additional elements, is connected to the general control system. The whole system is based on EPICS for the control network, and the modularization of the communication layers of the accelerator plays an important role in the proposed control architecture.

Active Magnetic Bearings Robust Control Design based on Symmetry Properties

This paper describes an Hinfin robust control design for an electromechanical system consisting of a rotary flexible spindle hovered by active magnetic bearings (AMB), whose potential uses in the machine-tool industry have been well documented. Symmetry properties are utilized to perform a model reduction avoiding the ill-conditioning of the matrices when Hinfin algorithms are solved and hence, facilitating the design of the controller. The better behavior of the system is probed by simulation in a complete model of a real device.

Experimental implementation of a networked input-output sporadic control system

Event-based control (EBC) is growing in importance since this paradigm leads to a better integration with networked systems. Particularly due to the distributed and asynchronous inherent nature of such systems. The reported main advantage is the reduction of the control rate allowing a less saturated communication network. This fact has been proved with different EBC schemes, as using impulse control schemes within stochastic environments and different PID structures. In this work, the experimental study of an event based input-output control scheme is presented, following the sporadic control approach and implemented in a networked environment. In this scenario, noise minimizes the advantages of event-based schemes. The use of a filtering strategy minimizes its effect, restoring the reduction of the control rate. This kind of approach leads to interesting practical applications. Simulation and experimental results show the performance of the control approach under study.