Jose Alexis De Abreu-Garcia

Fault diagnosis method for DC-DC converters based on the inductor current emulator

This paper proposes a fault diagnosis and identification method for non-isolated dc-dc converters. The method can detect the fault and identify the faulty switch, and switch fault type, in less than one switching cycle. The main idea is to apply the derivative of the inductor current, based on the modulation of the particular dc-dc converter, to provide a predictive current emulator model. The measured inductor current and its corresponding predicted current are used to diagnose the switch fault. The method, implemented on a DSP, is robust to common converter asymmetry such as load variations, input disturbances, etc. The proposed fault diagnosis method has been analyzed, tested, and validated for a boost converter.

Short circuit fault diagnosis for interleaved DC-DC converter using DC-link current emulator

Switch fault diagnosis is an important design criterion for dc-dc converters, as it can improve system reliability, prevent converter damage, and production losses to end users. This paper proposes a short circuit fault (SCF) diagnosis method for interleaved dc-dc converters that can detect the fault and identify the faulty switch in less than one switching cycle. The dc-link current is utilized as the diagnostic signature. The main idea is to apply the derivative of the dc-link current based on the modulation of the converter, and to propose a predictive dc-link current emulator model. The measured dc-link current, and its corresponding predicted current, obtained from the available control signals, are used as the input to the fault diagnosis module. The entire fault diagnosis method, including the dc-link current emulator and fault diagnosis modules, is implemented on a DSP. The method has been analyzed, tested, and validated for a certain converter.

Robustness considerations for p-step matrix integrators with uncertainty in the continuous system mode

Abstract Robustness measures for p-step matrix integrators are established. These measures are the quantitative bounds for either structured or unstructured perturbations existing in continuous-time systems to ensure that discrete versions of those systems obtained using p-step matrix integrators remain stable. Examples are given to illustrate the usefulness of the proposed measures. The effect of the sampling time T, the choice of the discretizing scheme, and the integrator step size on these robustness measures is discussed through examples.

Robustness analysis of two-step integrators with uncertainty in the system model

Abstract Quantitative bounds for the nonlinear perturbation of linear time-invariant continuous-time systems simulated using two-step matrix integrators are obtained. These bounds ensure that systems being simulated using two-step integrators remain stable under such perturbations. The effect of the sampling time T on the bounds is investigated via numerical examples.

Fault tolerant control method for interleaved DC-DC converters under open and short circuit switch faults

This paper proposes an adaptive democratic current sharing control scheme for interleaved dc-dc converters under faulty condition. The proposed fault tolerant control approach can achieve the desired output voltage generation, and equal current sharing among the remaining healthy modules as more and more modules fail. The main idea is to adaptively change the outer voltage and inner current controller gains once the fault is detected in the modules. The proposed control scheme is compared to the democratic current sharing control scheme under the fault condition and step load variation. The results show that it achieves improved output regulation and accurate current sharing among the modules. The presented fault tolerant control method has been analyzed, tested, and validated for the interleaved boost converter.