Current Controlled DC-DC Converter Research Articles

Electromagnetic interference of using 24Vdc current control buck converter for medical light emitting diode

Recently, there has been an increasing demand for low-power LED lighting fixtures that can contribute to a low-carbon society, however because AC voltage cannot be used directly for LEDs, an ACDC power converter is required for the LED equipment. Therefore, a buck converter as an ACDC power converter is applied to the LED equipment, but the effect of electromagnetic interference (EMI) becomes an issue which cannot be ignored in wireless communication equipment. In particular, because EMI radiated emission becomes a significant problem of communication signal discontinuations, the input of the buck converter has to be installed the EMI reduction filter equipment. This research shows EMI disturbance characteristics when a buck type current control DCDC converter circuit is used for an LED lighting equipment, and reports experimental results of EMI radiated emission characteristics improvement by changing the input and output circuit constants. Moreover, it is shown that can reduce to the floor noise level (background noise) when an output chip capacitor is inserted without an input filter.

LMI Control Design of a Non-Inverting Buck-Boost Converter: a Current Regulation Approach

This paper presents an analytical study of an input current-mode control based on a linear matrix inequalities (LMI) for a non-inverting buck-boost converter. The LMI control technique makes better the dynamic response of this converter in comparison with previous research works, where its currents has been regulated using a classical analogue PI controller with an additional pole. The main features of the selected converter are its voltage step-up and step-down properties, high efficiency, wide bandwidth and low input and output current ripples. All of these converter’s properties allows it to be used as a modular converter capable of being positioned at any converter locations in hybrid systems, which are formed by varying-voltage-sources, current controlled dc-dc converters and auxiliary storage devices such as batteries or capacitors. The designed state-feedback controller has the following aims, among others: pole placement constraints, control effort limitation, and decay rate and bandwidth improvement. The use of state-space averaging (SSA) method allows to describe LMI constraints which guarantees stability and provide good performances under a close loop pole region and control signal bound. The theoretical analysis have been simulated by means of Matlab and PSIM on an 800-W coupled-inductor buck-boost dc-dc switching converter.

Design Paradigm for Power Electronics-Based DC Distribution Systems

The design of a dc distribution system is posed as an optimization problem, which simultaneously utilizes time-domain analysis, distortion analysis, and stability analysis. The complete power distribution system is taken into consideration in the design process, capturing the interaction between various system components. Multiobjective optimization of mass and power loss metrics subject to transient performance constraints, distortion constraints (voltage and current ripple constraints), and stability constraints is carried out in the proposed design paradigm. This provides an organized framework for the design of dc power distribution systems. The approach is demonstrated through the design of a representative system that consists of a generation system, two isolating peak current controlled dc-dc converter modules, and two constant power loads. A sample design is chosen and verified using a detailed waveform level simulation.

Energy Management of a Fuel-Cell Serial–Parallel Hybrid System

In this paper, a serial-parallel hybrid (SPH) power system formed by a fuel cell (FC), an auxiliary storage device (ASD), and the current-controlled dc-dc converters responsible for the power management are realized by using the digital signal controller (DSC) TMS32F28335. The main energy management goal is to transfer energy from the sources (FC or ASD) to the load while ensuring dc bus voltage regulation and high power conversion efficiency. In addition, a safe and reliable operation of the system has to be achieved. The selected converter and its controller features are noninverting voltage step up and step down, high efficiency, regulation of input and output currents and low ripple values, and the ability to change from input to output current regulation loop, suddenly and smoothly, and vice versa. All these features allow it to be positioned in different FC system localizations and simplify the design of the master control. Simulation and experimental results have been validated on a 48-V 1200-W dc bus.

Energy Management DC System Based on Current-Controlled Buck-Boost Modules

This paper presents the design guidelines of a series hybrid fuel cell system, including control and protection loops. This hybrid system consists of a fuel cell (FC), an auxiliary storage device (ASD), and current-controlled DC-DC converters responsible for managing the energy transfer between the FC, the ASD, and the load. The main advantages of the selected converter are its voltage step-up and step-down properties, high efficiency, and low input and output current ripples, which enable it to be positioned in all system locations, provided the corresponding controllers are suitably designed. Also, using the same module for all system converters simplifies the design and construction tasks. The theoretical analyses have been verified by simulations and validated experimentally on a 48 V 1500 W purpose-built DC bus.

A High Efficiency FLL-Assisted Current-Controlled DC-DC Converter Over Light-Loaded Range

Current mode control is widely used in the switching power supply designs because of its fast response and less stability concern. However its performance at light load condition is limited by the precision of current sensing. In this work, instead of using high speed current sensor, a frequency-locked loop (FLL) is incorporated to extend the operation range with high power efficiency using a single controller. The 1.8-V output DC-DC converter has been fabricated with a standard 0.35-μm CMOS process and supplied from 2.7 to 4.3 V. Experimental results show that this switching converter operates from 100 to 600 kHz with the efficiency higher than 90% for the load current between 25 and 450 mA. The output voltage ripple is smaller than 30 mV with a 4.7- μH inductor and a 4.7-μF capacitor.