A resolver converter based upon a novel open-Loop Technique

The paper presents a novel technique for the determination of the angle from slowly-varying quadrature co-sinusoidal signals produced, for example, by position sensors. In the presented scheme applied to a resolver, the separately generated constant-frequency sine wave used for exciting the resolver together with an additional cosine wave are used as reference against which the amplitudes of the angle-dependent demodulated resolver sine and cosine signals are compared. At the instant equality between respective amplitudes of the signals are detected, two sample and hold circuits sample a voltage proportional to the angle of the shaft of the resolver from a triangular waveform generated from the reference signals. In theory, the sample and hold devices produce identical output voltages proportional to the unknown angle of the transducer. In order to improve the precision of the proposed converter, the two sample and hold circuits outputs are fed into a multiplexer to produce a single output that takes full advantage of the accurate comparison outside the peak regions of the signals. With this method, the validated output is obtained from the accurate comparisons involving the alternating pseudo-linear segments of the trigonometric signals. Another important feature of this converter is its robustness to amplitude fluctuations in the trigonometric reference signals which are used for the excitation of the resolver. A converter based on this technique has been successfully implemented using basic electronic components. Theory of operation, computer simulation and experimental results are given

A New Low Cost Linear Resolver Converter

A new low cost converter topology is proposed for sinusoidal position encoders. The converter enables determination of the angle from the sine and cosine signals of the encoder. When used with resolvers, the implementation of the present scheme takes advantage of the available excitation signal used to operate the device. This trigonometric reference signal is optimally used to generate an analogue signal equivalent to a digital look-up table (LUT). This enables determination of the mechanical angle without using LUT, A/D, and D/A converters. The scheme is optimized in order to achieve highest possible precision. Beside simplicity of its implementation, the proposed converter offers the advantage of robustness to amplitude fluctuation of the transducer excitation signal. The converter was implemented using ordinary low-cost analog components. The theory of operation, computer simulation, and experimental results are given

Mind the cuticle conductance: When resistance to cavitation is not enough for evaluating resistance to drought.

International audienc

An open-loop technique for angle determination from position encoders

The paper presents a novel technique for the determination of the angle from low-frequency quadrature cosinusoidal signals produced, for example, by position sensors. In the presented scheme applied to a resolver, the separately generated constant-frequency sine wave used for exciting the resolver together with an additional cosine wave are used as reference against which the amplitudes of the angle-dependent demodulated resolver sine and cosine signals are compared. At the instant equality between amplitudes of respective signals are detected, a sample and hold circuit samples a voltage proportional to the angle of the shaft of the resolver from a triangular waveform generated from the reference signals. This is a feed-forward method, which is an analog equivalent to digital look up table techniques. In order to improve the precision of the proposed converter, a new technique is used to take full advantage of the alternating pseudo-linear segments of the trigonometric signals. With this method, the sampling relies only on the accurate comparison outside the peak regions of the signals. A converter based on this technique has been successfully implemented using basic electronic components. Theory of operation, computer simulation and experimental results are given

Long-term performance analysis and power prediction of PV technology in the State of Qatar

?Solar photovoltaic (PV) energy in GCC?- the term seems convincing to many solar PV industries due to high solar exposure in GCC region. However, long-term effects such as dust accumulation and seasonal variation are major drawbacks for solar PV energy. This research aims to investigate PV performance for two years in the harsh environment of Qatar. For data collection, a wireless system has been developed to record critical parameters such as solar irradiance, relative humidity, ambient temperature, PV module temperature, dust, wind speed, and output PV power. Results show that due to panel dusting for eight months, the PV output power decreased by 50%. Also, owing to lower ambient temperatures, clearer sky and cleaner panels due to occasional rainfall, the PV panels show higher output power in Winter than in Summer season. Besides, within one-month, a cloudy condition in Winter causes 20% drop in average output power. Therefore, a strategic plan is needed to build and manage efficiently a PV solar plant in harsh environments such as of Qatar. Energy management requires prediction of energy yield. To this end, using machine-learning, a mathematical model has been established which can predict the output power from PV panels under different environmental conditions.Scopu