V. Valdivia

Behavioral Modeling of a Switched Reluctance Generator for Aircraft Power Systems

A system-level modeling technique for a switched reluctance generator (SRG) is described for aerospace applications. Unlike existing techniques, this model is very simple and only reproduces the average behavior of the input-output variables that are required for system-level analysis of the aircraft power distribution system. The model is parameterized from the measured generator response, avoiding the need for a detailed knowledge of the equipment structure, which may be unavailable. The modeling procedure is described in detail and validated by measurements on an SRG within an aircraft test facility.

Black-box modeling of DC-DC converters based on transient response analysis and parametric identification methods

Today, ¿black-box¿ behavioral models of power converters are becoming interesting for system-level analysis. These models can be used to evaluate the response of power electronics systems which are composed of commercial converters, since they can be fully parameterized by analyzing the actual converter response. In this paper a new identification method of ¿black box¿ models for DC-DC converters is presented. This method is based on the analysis of the step transient response of the converter, which is obtained by means of simple experiments. The identification of the model is carried out using well established fitting algorithms, which can be applied using commercial tools.

Impedance Identification Procedure of Three-Phase Balanced Voltage Source Inverters Based on Transient Response Measurements

Impedance-based models are commonly used to perform system-level stability analysis of distributed power systems. In this paper, a new impedance identification procedure for three-phase balanced voltage source inverters voltage source inverters (VSIs) is proposed. This procedure is based on the transient response of the inverter to simple passive load step tests. Transfer function models are obtained from the transient response by means of a well-established and easy to use identification algorithm. The performance of the proposal is validated through both simulation and experimental results obtained on VSIs for aircraft applications.

Black-Box Modeling of Three-Phase Voltage Source Inverters for System-Level Analysis

Modeling and simulation are powerful tools to design power distribution systems made up of multiple converters and loads, such as the system of the more-electric aircraft (MEA). However, a system designer usually has no access to detailed data of the power converters, due to confidentiality of manufacturers. Therefore, a black-box modeling approach is necessary. This paper proposes a large-signal black-box modeling technique of three-phase voltage source inverters. The resulting model is oriented to perform system-level analysis and is fully parameterized from the transient response of the converter, which is obtained through simple experimental tests based on low-cost equipment. Moreover, it does not represent the internal data of the converter, thus keeping the confidentiality of the manufacturer. The proposed method has been experimentally validated on a 5-kW actual inverter, which has been applied on the test bench of an MEA power distribution system.

Black-Box Model, Identification Technique and Frequency Analysis for PEM Fuel Cell With Overshooted Transient Response

Fuel cells are one of the most promising energy sources, especially for onboard applications. However, fuel cells present several drawbacks, such as slow dynamic response, load-dependent voltage, and unidirectional power flow, which cause an inappropriate vehicle operation. So, secondary energy sources and power converters must be implemented in order to satisfy fast changes in the current load and to store the energy delivered by the load if regenerative braking is intended. Taking into account the number and nature of the power converters, loads, secondary energy sources, and the possibilities for the control strategies, the design of a power distribution architecture based on fuel cells for transport applications is a complex task. In order to address these architectures, modeling and simulation design tools at system level are essential. This paper proposes a complete fuel cell black-box model which reproduces the behavior of a commercial fuel cell with overshooted transient response. The identification technique applied to parameterize the model components, based on manufacturers datasheets and a test based on load steps, is explained thoroughly. In addition, if only the fuel cell frequency response and manufacturers datasheet are available, an alternative parameterization methodology based on the fuel cell frequency response is presented. The fuel cell black-box model is validated experimentally using a commercial proton exchange membrane fuel cell. Two different parameterizations are carried out with the aim of verifying the robustness of both the fuel cell model and the proposed identification methodology.

Black-Box Behavioral Modeling and Identification of DC–DC Converters With Input Current Control for Fuel Cell Power Conditioning

Fuel cells are a prime candidate for alternative power source of future on-board power distribution systems such as those for the more-electric-aircraft and electric vehicles. These systems are comprised of a large number of power converters, often provided by a variety of manufacturers. Modeling and simulation are powerful tools to evaluate the system-level behavior but, due to confidentiality of manufacturers, black-box behavioral models of the converters are required instead of the conventional ones. This paper proposes a black-box modeling and identification method of dc-dc converters with input current control for fuel-cell power conditioning. The model is simple, requires low computational cost for simulation, and the identification procedure is based on simple experiments. Moreover, the model does not represent the internal structure of the converter, so it can be provided by the manufacturer while protecting confidential data. The method is illustrated in detail and validated by making use of a commercial dc-dc converter specifically designed for fuel-cell power conditioning.

An overview of the On Line Application of Frequency Response Analysis (FRA)

This paper provides an overview of on line application of frequency response analysis technique, this mean, without needing to interrupt the power supply. The electric utility industry is in the age of transition from periodic maintenance to condition based maintenance on essential substation power transformers in an effort to lower maintenance costs and maximize the use of existing equipment. The development of on-line diagnostics is in the critical path to achieve the condition based maintenance goal for power transformers. However, it is not clear how to deal with this project and multiple proceedings are possible. According to FRA, there is not a well establish procedure to develop the maintenance technique. This paper tries to show different methods and future trends to carry out the FRA measurements without disconnecting the transformer.

Design space boundaries of linear compensators applying the k-factor method

The design of linear compensators is usually based on the frequency response of the system, considering phase margin PM and cross-over frequency fc as the initial specifications. Applying the k-factor method for synthesis of linear compensators, not all combinations of fc and PM yield feasible or stable designs, and in many cases the design procedure is based on a trial and error procedure. The objective of this paper is to define the fc-PM design space of linear compensators designed applying the k-factor method. This design space can be used to determine in a straightforward way the most appropriate compensator for a given topology, sensor and modulator.

Black-box modeling of three phase voltage source inverters based on transient response analysis

Nowadays, black-box behavioral models of power converters are becoming interesting for system-level analysis. These models can be used to evaluate the response of power electronics systems which are composed of commercial converters, since they can be fully parameterized by analyzing the actual converter response. First black-box models of power converters have been recently proposed, but all of them are oriented to DC-DC converters. However, three-phase voltage source inverters are usually applied in current power electronics-based systems, such as aircraft power systems, and a black-box modeling method of this kind of converters has not yet been proposed. In this paper a large-signal black-box modeling method of three-phase voltage source inverters is proposed. The identification of the model is based on the analysis of the converter transient response, which is obtained by means of a set of simple experiments and easily usable fitting algorithms. An experimental validation of the proposed method has been carried out on a 5 kW actual inverter applied on an aircraft power system test bench.

Transformer and Series Inductance Integration for Harmonic Filtering in PWM Inverters Based in a Simple Design Procedure

PWM inverters are widely used in different power electronics applications. PWM waveforms have a harmonic content which should be filtered, typically based on LC topologies. If a transformer is required, the leakage inductance can be used as a series inductance for the LC filter. This work proposes an easy procedure for the integration of the series inductance for harmonic filtering inside the transformer, while the value of the leakage inductance can be determined by design.