This paper presents an improved electronic circuit for testing photovoltaic (PV) modules or strings by tracing their I-V and P-V characteristics. It consists of an electronic fast varying load based on a power MOSFET controlled by means of an innovative sweeping gate-source voltage in order to improve the tracing of the I-V characteristics on an oscilloscope. In order to prevent damage of data acquisition systems and mainly for use with high voltage PV strings, galvanic isolation is introduced for the sweeping signal as well as current and voltage measurements. In spite of this improved characteristics, the developed electronic circuit keeps the advantages of low cost and simplicity. Experimental results obtained with the electronic circuit are presented.
Abstract-This paper presents a comparative study between a new approach for robust speed estimation in induction motor sensorless control, using a reduced order Extended Kalman Filter (EKF), and the one performed by the full order EKF. The new EKF algorithm uses a reduced order state-space model that is discretized in a particular and innovative way. In this case only the rotor flux components are estimated, besides the rotor speed, while the full order EKF also estimates stator current components. This new approach strongly reduces the execution time and simplifies the tuning of covariance matrices. The performance of speed estimation using both EKF techniques is compared with respect to computation effort, tuning of the algorithms, speed range including low speeds, load torque conditions and robustness relatively to motor parameter sensitivity.I.
This paper presents a simple, robust and low-cost instrument for tracing current-and power-voltage characteristics of photovoltaic modules or low voltage strings using either an oscilloscope or a LabVIEW application developed for this purpose. It consists of a flexible electronic circuit, developed from a previous work, based on a fast varying load, built with a power MOSFET, which is controlled by means of a suitable gate-source voltage control signal in order to improve the tracing of current-and powervoltage characteristics on an oscilloscope. The new developments of this work include a low-cost DAQ system and an application developed in LabVIEW, which enhances the functionalities and flexibility of the current-voltage tracer. The robustness was strongly improved in view of field tests for fault diagnosis analysis. All details of the electronic circuit are shown in this paper and experimental results obtained with the new instrument are presented.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.