1,721,030 research outputs found
Random switching frequency in a synchronous-asynchronous digital voltage-mode control for dc-dc converters
No full text
Li-Ion Battery-Supercapacitor Hybrid Storage System for a Long Lifetime, Photovoltaic-Based Wireless Sensor Network
No full textThis paper proposes a power management architecture that utilizes both supercapacitor cells and a lithium battery as energy storages for a photovoltaic (PV)-based wireless sensor network. The supercapacitor guarantees a longer lifetime in terms of charge cycles and has a large range of operating temperatures, but has the drawback of having low energy density and high cost. The lithium battery has higher energy density but requires an accurate charge profile to increase its lifetime, feature that cannot be easily obtained supplying the wireless node with a fluctuating source as the PV one. Combining the two storages is possible to obtain good compromise in terms of energy density. A statistic analysis is used for sizing the storages and experimental results with a 5-W PV energy source are reported
Hysteresis-Based Mixed-Signal Voltage-Mode Control for dc-dc Converters
No full textThis paper investigates a mixed signal voltage-mode controller for dc-dc converters based on hysteresis modulation. In the proposed control architecture both switch turn-on and switch turn-off instants are determined asynchronously by comparing the converter output voltage to the voltage ramp driven by the digital control using a digital-to-analog converter (DAC). Under the dynamic point of view, the achievable performances resemble those of a multi-loop control with an internal hysteresis current control based on the estimated inductor current. Moreover, the switching frequency is kept constant under steady-state conditions by modulating the amplitude of the DAC ramp. The proposed control features good dynamic performance, frequency modulation during transients and low-complexity, since it requires a DAC, a comparator and, more importantly, low signal-processing requirement. Simulation and experimental results on a synchronous buck converter, where the digital control has been implemented in a field programmable gate array (FPGA), are also reported
Prediction of Limit-Cycles Oscillations in Digitally Controlled DC-DC Converters using Statistical Approach
No full textEMS Analysis on Digital Pulse Width Modulators
No full textIn this paper, a digital pulse width modulator (DPWM) is analysed from the point of view of the susceptibility to radio frequency interferences (RFI). The chosen DPWM architecture is based on the hybrid delay-line/counter scheme commonly used in the digital control of switched mode power supplies, since it increases the DPWM performance in terms of maximum switching frequency, duty-cycle precision and area consumption. This paper focuses on the DPWM performance degradation in presence of electromagnetic interferences (EMI) and, for this purpose, a hybrid PWM with time resolution down to 350 ps has been designed and manufactured in a standard 0.35 micrometer CMOS technology. Measurements and analytical analyses are presented for both EMI effects on the internal generated clock signal and on the PWM duty-cycle precision. The immunity degradation mechanisms are investigated, in particular by means of the proposed mathematical approach, demonstrating that the PWM susceptibility is strictly related to its functional design
Transmitting apparatus of digital signals on a supply line of electronics devices and corresponding method
No full textA power converter having a noise component and a modulator configured to vary a frequency of the noise component of the power converter on the basis of a digital signal to be transmitted
Supercapacitor-based Hybrid Storage Systems for Energy Harvesting in Wireless Sensor Networks
No full textPower management in multi-source multi-load energy harvesting systems
No full textThe forthcoming scenario of the wireless sensor network and the so called pervasive computing would greatly boost if all electronic systems involved in their deployment could feature some sort of energy self-sufficiency. In this application an aggressive power management solution is required in order to collect a sufficient amount of energy in storage elements in general from different power sources. This paper is focused on the development of the power supply systems, in particular on switching converters for energy harvesting applications. Its main goal is the development of high efficiency conversion systems, featuring the minimum number of conversion stages and of magnetic components, and the optimization of the power management. In particular the paper is focused on multi-input/multi-output dc-dc converters, enabling the connection of one or more sources of energy (solar, vibrational, RF, etc.), of some energy accumulation devices (micro-batteries, capacitors, supercapacitors), and several loads (microcontroller, transmitter, sensors, etc.). The modulation techniques and the power management are also discussed, to comply with multi-source/multi-load conditions
- …
