scholarly journals A simplified controller and detailed dynamics of constant off-time peak current control

2017 ◽  
Vol 68 (5) ◽  
pp. 390-395
Author(s):  
Alex Van den Bossche ◽  
Ekaterina Dimitrova ◽  
Vencislav Valchev ◽  
Firgan Feradov
Keyword(s):  
Current Control ◽  
Duty Ratio ◽  
Digital Controllers ◽  
Constant Frequency ◽  
Peak Current ◽  
Time Dynamics ◽  
Temperature Range ◽  
Wide Range ◽  
Off Time ◽  
A Current

Abstract A fast and reliable current control is often the base of power electronic converters. The traditional constant frequency peak control is unstable above 50 % duty ratio. In contrast, the constant off-time peak current control (COTCC) is unconditionally stable and fast, so it is worth analyzing it. Another feature of the COTCC is that one can combine a current control together with a current protection. The time dynamics show a zero-transient response, even when the inductor changes in a wide range. It can also be modeled as a special transfer function for all frequencies. The article shows also that it can be implemented in a simple analog circuit using a wide temperature range IC, such as the LM2903, which is compatible with PV conversion and automotive temperature range. Experiments are done using a 3 kW step-up converter. A drawback is still that the principle does not easily fit in usual digital controllers up to now.

scholarly journals Control Techniques and Power Factor Correction Methods: A Review

2018 ◽  
pp. 1-13
Author(s):  
Ganiyu Adedayo Ajenikoko ◽  
Oluwatomi Adigun ◽  
Amend Olayinka Rafiu
Keyword(s):  
Power Factor ◽  
Power Factor Correction ◽  
Constant Load ◽  
Current Control ◽  
Control Measures ◽  
Control Technique ◽  
Duty Ratio ◽  
Current Loop ◽  
Switching Frequency ◽  
Constant Frequency

The ratio of real power flowing into the load to the apparent power in a circuit is referred to as the power factor (PF). It has no unit as its values lie between 0 and 1. Power factor correction (PFC) leads to a reduction in apparent power drawn from the ac source which in turn saves energy and minimizes the transmission losses. This paper reviews various methods used for PFC as well as the various control measures for power factor. The correction methods include distributed PFC, group PFC, centralized PFC and combined PFC. Distributed PFC is applicable to large electrical equipment with constant load and power with long connection times. Combined PFC is the hybrid between a distributed and a centralized correction method. Peak current control technique makes use of constant switching frequency even though, the presence of sub-harmonic oscillations at a duty cycle greater than 50% is a disadvantage. The presence of constant switching frequency and better input current waveforms are some of the applications of average current control. In the discontinuous current pulse width modulation (PWM) control, the internal current loop is completely eliminated so that the switch is at a constant frequency. In nonlinear carrier controllers, the duty ratio is determined by comparing a signal derived from the main switch current with a periodic nonlinear carrier waveform. Therefore, combined PFC and nonlinear carrier controllers are more accurate PFC methods for the power plant because they employ a high power factor boost converter with low total harmonic distortion for installations of large equipment with a constant load. This research paper forms a basis for power system planning as it assists in recommending the appropriate and adequate technique(s) for correcting and controlling the pf of the factory.

Analysis and Modeling of Nonlinear Effects in Constant-Frequency Peak-Current Control

2021 ◽  
Vol 31 (15) ◽  
Author(s):  
Marija Glišić ◽  
Predrag Pejović
Keyword(s):  
Nonlinear Effects ◽  
Higher Order ◽  
Current Control ◽  
Model Parameters ◽  
Output Current ◽  
Signal Model ◽  
Constant Frequency ◽  
Peak Current ◽  
Frequency Peak ◽  
Numerical Approaches

In this paper, constant-frequency peak-current control is analyzed focusing on the operation above the subharmonic threshold limit. The analysis is performed by mixing analytical and numerical approaches. Two levels of normalization are introduced: on the converter level and on the switching cell level, resulting in unified analysis regardless of the converter type. A function that maps the inductor current value at the beginning of a switching period to its value at the end of the switching period is derived. The analysis is performed by iterating this mapping, leading to information of the inductor current periodicity and the switching cell averaged output current. It is shown that before reaching chaotic state a converter passes through a sequence of bifurcations involving discontinuous conduction modes characterized by higher order periodicity. Boundaries of the region where the higher order discontinuous conduction modes occur are derived. Obtained dependence of the switching cell output current average on the operating parameters is used to derive a small signal model. The model parameters expose huge variations in the areas of deep subharmonic operation. The results are experimentally verified.

scholarly journals Input switched closed-loop single phase ĈUK AC to DC converter with improved power quality

2019 ◽  
Vol 10 (3) ◽  
pp. 1373
Author(s):  
Md. Shamsul Arifin ◽  
Nur Mohammad ◽  
Mohammad Ibrahim Khalil ◽  
Mohammad Jahangir Alam
Keyword(s):  
Power Factor ◽  
Single Phase ◽  
Closed Loop ◽  
Harmonic Distortion ◽  
Open Loop ◽  
Current Control ◽  
Control Loop ◽  
Cuk Converter ◽  
Wide Range ◽  
A Current

<span lang="EN-US">A new closed loop AC to DC ĈUK converter is presented in this paper. The conventional ĈUK AC to DC converter has no feedback circuit. Thereby, the output voltage of the converter changes while changing the load. The proposed closed loop converter can regulate voltage with the variation of load over a wide range. Moreover, the power factor and Total Harmonic Distortion (THD) of the supply side current found quite satisfactory from this closed loop ĈUK converter. The converter operates in four steps with a different combination of voltage polarities and switching states. The feedback path consists of a voltage control loop and a current control loop. The closed loop ĈUK converter in this study is compared with the open loop version. Additionally, the comparison is made with the conventional converter of the same topology. The effectiveness in terms of power factor and THD of the proposed converter is verified using simulation results.</span>

Enabling highly reversible sodium metal cycling across a wide temperature range with dual-salt electrolytes

2021 ◽  
Author(s):  
Akila C. Thenuwara ◽  
Pralav P. Shetty ◽  
Neha Kondekar ◽  
Chuanlong Wang ◽  
Weiyang Li ◽  
...  
Keyword(s):  
Wide Temperature Range ◽  
High Energy ◽  
Liquid Electrolyte ◽  
Metal Cycling ◽  
Temperature Range ◽  
Sodium Metal ◽  
Wide Range

A new dual-salt liquid electrolyte is developed that enables the reversible operation of high-energy sodium-metal-based batteries over a wide range of temperatures down to −50 °C.

scholarly journals Palladium and Copper: Advantageous Nanocatalysts for Multi-Step Transformations

Nanomaterials ◽  
2021 ◽  
Vol 11 (8) ◽  
pp. 1891
Author(s):  
Antonio Reina ◽  
Trung Dang-Bao ◽  
Itzel Guerrero-Ríos ◽  
Montserrat Gómez
Keyword(s):  
Chemical Properties ◽  
Added Value ◽  
Solid Supports ◽  
Nanosized Materials ◽  
Nano Structures ◽  
Liquid Phases ◽  
Wide Range ◽  
Synthetic Methodologies ◽  
Physical And Chemical ◽  
A Current

Metal nanoparticles have been deeply studied in the last few decades due to their attractive physical and chemical properties, finding a wide range of applications in several fields. Among them, well-defined nano-structures can combine the main advantages of heterogeneous and homogenous catalysts. Especially, catalyzed multi-step processes for the production of added-value chemicals represent straightforward synthetic methodologies, including tandem and sequential reactions that avoid the purification of intermediate compounds. In particular, palladium- and copper-based nanocatalysts are often applied, becoming a current strategy in the sustainable synthesis of fine chemicals. The rational tailoring of nanosized materials involving both those immobilized on solid supports and liquid phases and their applications in organic synthesis are herein reviewed.

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