Commercializing Emerging Renewable Energy: A Case Study

A broad scientific consensus exists that the global climate is changing. The Earth’s surface temperature could rise significantly over the next few decades, leading to us witnessing an entirely new and unknown planet. Improved energy efficiency, decreasing use of fossil fuels and wide diffusion of various renewable energy sources are among the focal measures to limit global warming to a sustainable level. The objective of this study is to analyse how renewable energy, such as wind power and bioenergy, could be efficiently commercialized. The evaluation is based on a case study and expert analyses exploiting lateral and parallel thinking methods, and group decision support systems tools. The results reveal that some of the generated ideas are ready for implementation to commercialize renewable energy, whereas others still require technical and commercial development, and improvements before maturity

Control System Commissioning of Fully Levitated Bearingless Machine

The bearingless permanent magnet synchronous motor (BPMSM) is a compact motor structure that combines the motoring and bearing functions based on well-designed integrated windings for generating both torque and magnetic suspension force. In order to achieve a successful high-performance control design for the BPMSM, an adequate model of the rotor dynamics is essential. This paper proposes simplified multiple-input and multiple-output (MIMO) control approaches, namely the pole placement and the linear-quadratic regulator (LQR), that allow to carry out identification experiments in full levitation. Additionally, the stability of the MIMO levitation controller is verified with the rotation tests. Compared with other recently published works, the novelty of this paper is to experimentally demonstrate that a stable fully levitated five-degrees-of-freedom (5-DOF) operation of a bearingless machine can be achieved by the proposed approach, and thereby, options for commissioning of such a system are obtained

Online Identification of a Mechanical System in the Frequency Domain with Short-Time DFT

A proper system identification method is of great importance in the process of acquiring an analytical model that adequately represents the characteristics of the monitored system. While the use of different time-domain online identification techniques has been widely recognized as a powerful approach for system diagnostics, the frequency domain identification techniques have primarily been considered for offline commissioning purposes. This paper addresses issues in the online frequency domain identification of a flexible two-mass mechanical system with varying dynamics, and a particular attention is paid to detect the changes in the system dynamics. An online identification method is presented that is based on a recursive Kalman filter configured to perform like a discrete Fourier transform (DFT) at a selected set of frequencies. The experimental online identification results are compared with the corresponding values obtained from the offline-identified frequency responses. The results show an acceptable agreement and demonstrate the feasibility of the proposed identification method

Force controllers for AMB systems with position and current feedback

In this paper, the state-of-the-art AMB controller structure, with an outer centralized position control loop with reference currents and inner current control loops, is replaced with an outer control loop with force references and inner flux control loops. The linearization of the force actuators and different control schemes of the centralized outer control for the radial suspension are considered. The operation of the proposed control under a zero bias is verified by simulations. The proposed control solution can achieve a dynamic performance comparable with that of a controller with the classical bias current.</jats:p

Comparison of Excitation Signals in Active Magnetic Bearing System Identification

Active magnetic bearings (AMBs) offer frictionless suspension, vibration insulation, programmable stiffness, and damping, among other advantages, in levitated rotor applications. However, AMBs are inherently unstable and require accurate system models for the high-performance model-based multi-input multi-output control of rotor position. Control electronics with high calculation capacity and accurate sensors of AMBs provide an opportunity to implement various identification schemes. A variety of artificial excitation signal-based identification methods can thus be achieved with no additional hardware. In this paper, a selection of excitation signals, namely the pseudorandom binary sequence (PRBS), chirp signal, multisine, and stepped sine are presented, applied, and compared with the AMB system identification. From the identification experiments, the rotor-bearing system, the inner current control loop, and values of position and current stiffness are identified. Unlike recently published works considering excitation-based identification of AMB rotor systems, it is demonstrated that identification of the rotor system dynamics can be carried out using various well-established excitation signals. Application and feasibility of these excitation signals in AMB rotor systems are analyzed based on experimental results

Cascaded position-flux controller for an AMB system operating at zero bias

The paper reports on the implementation and the design of a controller for a fuel cell blower (FCB) with active magnetic bearings (AMBs). The cascaded position-fluxcentralized controller is comprised of a centralized position control loop and an inner flux control loop. The last one is based on state estimation without explicit flux measurements. As the position control is not dependent on the magnetic field nonlinearities, such a control structure enables operation under a zero bias. The practical working implementation of a flux control for the industrial levitated rotor is shown for the first time. The flux control gives better results than current control for both normal and zero bias operation. The system is analyzed fully, combining rotor dynamics and power amplifier analyses simultaneously. The importance of using the coil voltage in addition to current and practical treatment of the flux control is revealed. The centralized position-flux controller is compared with a state-of-the-art cascaded position-current control, which has inner current control loops. The proposed control solution with a zero bias can achieve a dynamic performance comparable that of a controller with the classical bias current