Design Of Passive Damping Research Articles

Improved design of passive damping for single phase grid‐connected LCL filtered inverter considering impedance stability

AbstractGrid‐connected inverters with an inductor–capacitor–inductor (LCL) filter usually require the implementation of damping in the filter to suppress the resonance associated with the filter and hence ensure internal stability. The value for the damping resistor is commonly chosen as one‐third of the capacitive reactance at the resonance frequency of the LCL filter. However, this commonly‐used principle does not take into account the external stability of the inverter, i.e. the potential for an interaction between the inverter output impedance and the grid impedance. This work discusses a new design for the damping resistor to assure the external stability of the voltage source inverter as well as its internal stability. The analysis shows that the proposed design can ensure the external stability of the voltage source inverter with different grid impedances as well as robustness against the variations of the filter parameters while maintaining low power losses and an acceptable attenuation rate for high‐frequency harmonics. To validate the theoretical analysis, a 1 kW, 110 V laboratory prototype is implemented. The obtained results confirm the applicability of the proposed design approach.

Passivity-Based Design of Passive Damping for LCL-Type Grid-Connected Inverters to Achieve Full-Frequency Passive Output Admittance

Passivity-Based Design of Passive Damping for <i>LCL</i>-Type Grid-Connected Inverters to Achieve Full-Frequency Passive Output Admittance

Identification and Control of an MR Damper With Stiction Effect and its Application in Structural Vibration Mitigation

This paper presents the parameter identification and control of a magnetorheological (MR) damper with stiction effect and its application to seismic protection of a model two-story structure. This semi-active device is utilized to reduce the vibration of the model structure in response to earthquake excitations. First, modified Bingham and LuGre models which consider the stiction effect and the velocity-dependent nature of the damper force are proposed. The parameters of the models are identified by solving a nonlinear optimization problem. The Bingham model is considered because of its simple structure to be used in linear parameter varying (LPV) design framework. The parameter identification is performed while the MR damper is attached to the structure. These models are verified experimentally for different operating conditions showing an acceptable level of accuracy. The subsequent part of the paper addresses the design of different types of controllers to command the MR damper to suppress the structural vibrations of a model building due to earthquake excitations. Two types of controllers are considered in this study: 1) an <formula formulatype="inline" xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex Notation="TeX">$H_{\infty }$</tex></formula> inverse control based on the mixed-sensitivity design and 2) a dynamic output-feedback LPV controller. In the former one, an <formula formulatype="inline" xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex Notation="TeX">$H_{\infty }$</tex></formula> controller is designed for the linear structure and the modified LuGre-based inverse model is used to determine the required voltage from the commanded force. The LPV controller is designed for the combined structure and MR damper based on the modified Bingham model considering the damper velocity as the scheduling parameter. Both controllers are combined with a classical anti-windup scheme to compensate the effect of the saturation on the control voltage. An optimal passive damping design is also obtained for comparison purposes. The performance of the controllers is compared with the passive damping case and clipped-optimal controller for the El Centro and Northridge earthquake inputs with different intensities. The experimental results show the improved performance of the LPV controller design in terms of the maximum acceleration and the RMS values of the structure response.

Dual Active and Passive Control of Large Flexible Structures

A unified passive damping design algorithm, using active control design techniques and least squares method, is developed to improve the stability and performance of closed-loop controlled structures. To achieve the stringent requirements of large flexible structures (LFS), dual active/passive control using interacting substructure decentralized control and unified passive damping design method is introduced. Physical coordinates are used in modeling; since no modal data is used, no modal errors are involved in the modeling process. Examples are presented to illustrate the design procedures and their effectiveness.