scholarly journals Modeling of Average Current in Non-Ideal Buck and Synchronous Buck Converters for Low Power Application

Electronics ◽  
2021 ◽  
Vol 10 (21) ◽  
pp. 2672
Author(s):  
Sumukh Surya ◽  
Mohan Krishna Srinivasan ◽  
Sheldon Williamson
Keyword(s):  
Resonant Frequency ◽  
Low Power ◽  
Low Frequency ◽  
Open Loop ◽  
Duty Ratio ◽  
Buck Converters ◽  
Balance Equations ◽  
Matlab Simulink ◽  
Power Application ◽  
The Ideal

In this paper, a comparative analysis of the average switch/inductor current between ideal and non-ideal buck and synchronous buck converters is performed and verified against a standard LTspice model. The mathematical modeling of the converters was performed using volt-sec and amp-sec balance equations and analyzed using MATLAB/Simulink. The transients in the output voltage and the inductor current were observed. The transfer function of the switch current to the duty cycle (Gid) in open loop configuration for low-power converters operating in continuous conduction mode (CCM) was modeled using thestate space averaging (SSA) technique and analyzed using MATLAB/Simulink. Initially, using the volt-sec and amp-sec, balance equations for the converters were modeled. The switch current to duty ratio (Gid) was derived using the SSA technique and verified using standard average models available in LTspice software. Though the Gid was derived using various methods in earlier works, the analyses of parameters such as low frequency gain, stability, resonant frequency and the location of poles and zeros were not presented. It was observed that the converters were stable, and the non-ideal converter showed smaller resonant frequency than the ideal converter due to the equivalent series resistances (ESR) of the inductor and the capacitor. The non-ideal converters showed higher stability than the ideal converters due to the placement of the poles closer to the s-plane. However, the Gid of the non-ideal converters remained the same in the open loop configuration.

Design and Implementation of a Dimmable LED Driver with Low-Frequency PWM Control

2013 ◽  
Vol 284-287 ◽  
pp. 2538-2542
Author(s):  
Hung Liang Cheng ◽  
Chun An Cheng ◽  
Chao Shun Chen ◽  
Kuan Lung Huang
Keyword(s):  
High Frequency ◽  
High Efficiency ◽  
Low Frequency ◽  
Buck Converter ◽  
Duty Ratio ◽  
Buck Converters ◽  
Resonant Converter ◽  
Switching Loss ◽  
Led Driver ◽  
Frequency Pulse

This paper proposes a high-efficiency dimmable LED driver for light emitting diodes (LED). The developed LED driver consists of a full-bridge resonant converter and six buck converters. The function of the full-bridge resonant converter is to obtain a smooth dc-link voltage for the buck converters by phase-shift modulation (PSM) while that of the six buck converters is to drive six LED modules, respectively. The gate voltage of the active switch of each buck converter is a combination of high-frequency and low-frequency pulses. The duty ratio of the high-frequency pulse controls the LED voltage and thereby, controls the amplitude of LED current. LEDs are dimmed by low-frequency pulse-width modulation (PWM) to vary the average current flowing through LED. Circuit equations are derived and circuit parameters are designed. High circuit efficiency is ensured by operating the active switches at zero-voltage switching-on to reduce the switching loss. Finally, a prototype circuit was built to verify the accuracy and feasibility of the proposed LED driver.

scholarly journals Modeling of Average Current in Ideal and Non-Ideal Boost and Synchronous Boost Converters

Energies ◽  
2021 ◽  
Vol 14 (16) ◽  
pp. 5158
Author(s):  
Sumukh Surya ◽  
Sheldon Williamson
Keyword(s):  
Transfer Function ◽  
Low Frequency ◽  
Load Resistance ◽  
Open Loop ◽  
Current Control ◽  
Duty Ratio ◽  
Boost Converters ◽  
Loop Transfer Function ◽  
Average Current ◽  
Conduction Mode

This paper provides a modeling approach for average current control (ACC) operating in open-loop configuration. The converters chosen are non-ideal boost and synchronous boost converters operating in continuous conduction mode (CCM). Initially, these converters are mathematically modeled considering all the non-idealities using volt-sec and amp-sec balance equations and simulated using MATLAB and Simulink. The open-loop transfer function of the switch current or inductor current (Gid) to the duty ratio is derived using the state space averaging (SSA) technique and analyzed using MATLAB/Simulink. It is observed that the Gid of the converters is highly stable in open loop. A larger magnitude resonance is observed in ideal boost and synchronous boost converters than the non-ideal converters. However, the low frequency gain and the crossover frequency remained the same. With the increase in the load resistance, higher resonance and lower low frequency gain is observed in non-ideal boost and non-ideal boost synchronous boost converters. The derived transfer function is validated against the standard switch model using LTSpice software.

Design of a Low-Voltage Low-Power CMOS Operational Amplifier

2013 ◽  
Vol 380-384 ◽  
pp. 3283-3286
Author(s):  
Lin Hai Cui ◽  
Rui Xu ◽  
Zhan Peng Jiang ◽  
Chang Chun Dong
Keyword(s):  
Low Power ◽  
Operational Amplifier ◽  
High Efficiency ◽  
Low Voltage ◽  
Low Frequency ◽  
Open Loop ◽  
Common Source ◽  
Output Stage ◽  
Input Stage ◽  
Current Mirrors

A low voltage, low power two-stage operational amplifier (op-amp) was proposed in this paper. A folded-cascode structure is used in the input stage of the amplifier to get high gain. Current mirrors are used in the input stage to make the transconduotance constant. A simple push-pull common source amplifier is adopted as the output stage to take the advantages of its high efficiency. The experimental results show that the unity-gain bandwidth is 12.5MHz, the low-frequency open-loop voltage gain is 100dB,the phase margin is 65°, and power dissipation is 98.8μw.

Temperature control in a chemical reactor through variable area of the heat transfer surface. Experimental verification

1982 ◽  
Vol 47 (2) ◽  
pp. 446-453
Author(s):  
Josef Horák ◽  
František Jiráček ◽  
Libuše Ježová
Keyword(s):  
Batch Reactor ◽  
Exothermic Reaction ◽  
Chemical Reactor ◽  
Open Loop ◽  
Heat Transfer Surface ◽  
Laboratory Reactor ◽  
Hysteresis Control ◽  
Relay With Hysteresis ◽  
Rate Of Response ◽  
The Ideal

A possibility has been tested in the paper of the feed back control of temperature of the reaction mixture in a batch reactor with an exothermic reaction through the variable area of the cooling surface. The measurement were carried out in a laboratory reactor with a retractable cooler which was being immersed into the reaction mixture. The speed of motion of the cooler was sufficiently high permitting the process of immersion to be regarded as practically instantaneous. The aim of the control was to stabilize the set point temperature of the reaction mixture by a two-point controler. In dependence on the rate of response of the system to a change of the section variable either the ideal relay or the relay with hysteresis control algorithmus were used. The results of measurements showed that with the aid of a retractable cooler the temperature could be controlled safely even in those cases, in which the control by the variable flow rate of the coolant was unfeasible. The verification was carried out in the open-loop instable operating point of the reactor.

scholarly journals Influence of Duty Ratio and Current Mode on Robot 316L Stainless Steel Arc Additive Manufacturing

Metals ◽  
2021 ◽  
Vol 11 (3) ◽  
pp. 508
Author(s):  
Ping Yao ◽  
Hongyan Lin ◽  
Wei Wu ◽  
Heqing Tang
Keyword(s):  
Stainless Steel ◽  
Additive Manufacturing ◽  
Heat Input ◽  
Low Frequency ◽  
Single Pulse ◽  
Pulse Mode ◽  
Double Pulse ◽  
Duty Ratio ◽  
Utilization Rate ◽  
Specimen Height

Wire and arc additive manufacturing (WAAM) is usually for fabricating components due to its low equipment cost, high material utilization rate and cladding efficiency. However, its applications are limited by the large heat input decided by process parameters. Here, four 50-layer stainless steel parts with double-pulse and single-pulse metal inert gas (MIG) welding modes were deposited, and the effect of different duty ratios and current modes on morphology, microstructure, and performance was analyzed. The results demonstrate that the low frequency of the double-pulse had the effect of stirring the molten pool; therefore, the double-pulse mode parts presented a bigger width and smaller height, finer microstructure and better properties than the single-pulse mode. Furthermore, increasing the duty ratio from 35% to 65% enlarged the heat input, which then decreased the specimen height, increased the width, and decreased the hardness and the tensile strength.

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