Showing papers by "Juan Antonio Gómez Galán published in 2009"

Measuring the I-V curve of PV generators

Abstract: This article discusses a new experimental way to measure the I-V characteristic curve of photovoltaic (PV) generators based on DC-DC converters The obtained results show that the classical buck and boost converters are not capable of reproducing the whole I-V curve of PV generators and that the single-ended primary inductance converter (SEPIC) is optimal for this application We propose a method based on SEPIC converters in parallel connection, operating in an interleaved mode This method gives advantages with respect to the use of conventional methods

Tunable Linear MOS Resistors Using Quasi-Floating-Gate Techniques

Abstract: A family of tunable MOS resistors based on quasi-floating-gate (QFG) transistors biased in the triode region is analyzed in this paper. From the study results, a new device that outperforms previous implementations, is presented. By means of a capacitive divider, the ac component of the drain-to-source voltage scaled with a factor alpha les 1 is added to the gate-to-source voltage leading to a cancellation of the nonlinear terms. The effect of alpha on resistor linearity is analytically studied. Simulation results are also provided for different technologies. Finally, a complete transconductor has been built which preserves the linearity of the MOS resistor. Three versions of the transconductor have been fabricated for different values of alpha (alpha = 0, 0.5, and 1) in a 0.5 mum CMOS technology with plusmn1.65-V supply voltage. Experimental results show (for alpha = 1 ) a THD of - 57 dB (HD2=-70 dB) at 1 MHz for 2-V peak-to-peak differential input signal with a nominal ac-transconductance of 200 muA/V and a power consumption of 3.2 mW.

Methodology and experimental system for measuring and displaying I–V characteristic curves of PV facilities

Abstract: This paper describes a methodology and the developed system for measuring, capturing, and displaying I–V and P–V characteristic curves of photovoltaic (PV) modules or arrays based on single-ended primary inductance converters (SEPIC) in parallel connection, operating in interleaved mode. The proposed methodology and the developed system allow the real time capture and displaying of the I–V and P–V curves of a PV panel or array, and show several advantages with regard to classical methods: simple structure, scalability, fast response, versatility, direct display, and low cost. The measuring of the characteristic curves of PV modules includes high speed of response and high fidelity, with low ripple. An experimental prototype based on four SEPIC converters in parallel connection has been implemented to validate the proposed methodology. This new methodology and experimental system has been registered in the Spanish Patent and Trademark Office with the number P200930198. Copyright # 2009 John Wiley & Sons, Ltd.

Low-voltage tunable pseudo-differential transconductor with high linearity

Abstract: A novel tunable transconductor is presented. Input transistors operate in the triode region to achieve programmable voltage-to-current conversion. These transistors are kept in the triode region by a novel negative feedback loop which features simplicity, low voltage requirements, and high output resistance. A linearity analysis is carried out which demonstrates how the proposed transconductance tuning scheme leads to high linearity in a wide transconductance range. Measurement results for a 0.5 μm CMOS implementation of the transconductor show a transconductance tuning range of more than a decade (15 μA/V to 165 μA/V) and a total harmonic distortion of −67 dB at 1 MHz for an input of 1 Vpp and a supply voltage of 1.8 V.

Measurement method for PV modules based on DC-DC converters with microcontroller

Abstract: This paper proposes a versatile system to test and measure systematically the real evolution for the I-V characteristic curves of photovoltaic (PV) modules or arrays. The system employs a novel circuit solution based on DC-DC converters that shows several advantages with regard to classical methods: simple structure, scalability, fast response and low cost. The measure of the desired characteristics of photovoltaic modules includes high speed of response and high fidelity. The prototype is governed by a microcontroller and experimental results show the usefulness of the proposed system. Moreover, a user environment has been developed in order to control the overall system from a computer.