Multiple Output Voltages Research Articles

Single-Switch Multioutput Charger Using Voltage Multiplier for Series-Connected Lithium-Ion Battery/Supercapacitor Equalization

Voltage equalization is essential for series-connected energy storage cells, such as lithium-ion cells and supercapacitors (SCs), because it ensures years of service life and maximizes the available energies of cells. Conventional equalizers and multioutput chargers require many switches and/or a multiwinding transformer, which are not desirable in terms of circuit simplicity and extendibility. In this paper, single-switch multioutput chargers based on a combination of an input cell (which generates a square voltage wave) and a voltage multiplier (which produces multiple uniform output voltages) are proposed. A fundamental operation analysis is made, and a dc equivalent circuit is derived to describe their charging and equalization behaviors. Experimental charge tests were performed separately for series-connected SC modules and lithium-ion batteries from voltage-unbalanced conditions. The least charged module/battery was charged preferentially; as a result, all of the modules/batteries were charged to a desired uniform voltage level while eliminating the voltage imbalance.

A 10-b Two-Stage DAC with an Area-Efficient Multiple-Output Voltage Selector and a Linearity-Enhanced DAC-Embedded Op-Amp for LCD Column Driver ICs

This work proposes a 10-b two-stage DAC with an area-efficient multiple-output voltage selector and a linearity-enhanced DAC-embedded op-amp for LCD column driver ICs. The proposed voltage selector is divided into two stages, MSB and LSB decoders; this design requires fewer switches compared with tree-type voltage selectors, enabling a smaller die area. The proposed 6-b two-voltage selector occupies only 61% of the area needed for a 6-b tree-type two-voltage selector. This study also develops a generalized architecture for an area-efficient voltage selector for multiple outputs. To improve the linearity of the DAC-embedded op-amp, the differential pairs operate at the edge of the saturation region. The 10-b DAC prototypes were produced with 0.35- μm/0.5- μm CMOS technology with the worst DNL/INL being 0.44/0.58 LSB.

Buck and Boost Converters With Transmission Lines

The switch mode power conversion circuits buck, boost, and buck-boost incorporate a power inductor as an energy storage device. If the power inductor in these fundamental circuits is replaced with a transmission line, new power conversion circuits will emerge. By introducing microwave properties, such as propagation delay and characteristic impedance, new functions may be feasible in the area of power conversion. Examples of such functions could be inverting and noninverting voltage polarity abilities or circuits, which share switch components between multiple output voltages reducing the number of semiconductors needed. Alternatively, the buck-boost power converter circuit may give rise to new high-efficiency radio circuits in the area of microwave technology.

Reducing electromagnetic interferences in flyback AC-DC converters based on the frequency modulation technique

One of the most preferable types of switched-mode power supplies (SMPS) is the flyback converter, due to its wide range of application areas. Properties such as low cost, provision of multiple output voltage terminals, and higher efficiencies make it important, and hence its usage in technologies including cell phone chargers, personal computers, set-top boxes, and televisions is increasing. Special attention should be paid to the design of this type of converter due to its working principles and electromagnetic interference (EMI) performance. Rapid switching of high current and high voltage during the operation of SMPS causes an EMI problem. The level of the EMI noise should be reduced in order to not interfere with the operation of other equipment. One of the methods for mitigating EMI emissions is the frequency modulation (FM) technique. In this paper, the FM technique, which has been increasingly used as an EMI-reduction method in SMPS, is investigated. The modulation technique that was applied to the switching frequency of the flyback converter is analyzed and its effect on the EMI performance is discussed. The FM technique was tested on an AC-DC flyback converter prototype that was built with an L6566B integrated circuit. Conducted emission noises from the SMPS were measured using an EMI receiver. Experimental results showed that EMI levels were reduced after the application of the FM method.

STROMBOLI®: a new platform for Isolated DC-DC Converters with reliable operation from −55°C up to 225°C

This paper presents a new high-temperature isolated DC-DC converter platform called STROMBOLI®. It also discusses how this converter can be associated with the various solutions proposed by CISSOID for Point-of-Load (POL) regulators that can be either linear or switched mode. STROMBOLI® has been optimized to efficiently convert input voltages up to 350V into multiple output voltages up to +/−25V. As an example, in a +/−12V symmetrical output configuration, standard STROMBOLI® can deliver 25W with efficiencies up to 70% at 225°C. The galvanic isolation between input and outputs is at least 10MΩ at 500V. As the main objective of this development was to provide designers with a solution highly flexible, scalable, and easily adaptable to their specific requirements, we selected well-known and robust flyback architecture. Efficiency has been optimized thanks to synchronous rectification. However it can be replaced by a standard rectification in order to reduce the bill-of-material (BOM). A magnetic feedback provides the output voltage temperature stability and the load regulation. STROMBOLI® also includes an Under-Voltage-Lockout (UVLO) function and the pulse-by-pulse current sensing provides intrinsic output current limitation in case of overload or short-circuits. STROMBOLI® is a state-of-the-art, turnkey reference design suitable for 225°C reliable operation and is part of high temperature DC-DC converters VOLCANO family.

Intermediate bus architecture: is it for everyone?

With all the attention accorded to the intermediate bus architecture (IBA) structure, it would be easy to believe that it will soon take over all other traditional methods of supplying multiple output voltages on a printed circuit board (PCB). It is true that in some situations the size, efficiency and cost of the power solution will be better if the IBA approach is followed, but in many other instances, one or more of these parameters will be worse, not better. The decision to use IBA must, therefore, be assessed on a case-by-case basis. The issues that must be considered are discussed in this article.

A new multiple-output hybrid power supply

A novel hybrid power supply to perform the precise regulation of multiple-output voltages is presented. It is composed of an improved forward-type multiple-output converter as a preregulator and continuous series regulators using MOSFETs as voltage droppers. The steady-state and the dynamic cross-regulation characteristics are analyzed and compared both theoretically and experimentally for the conventional and improved forward-type multiple-output converters. As a result, it is clearly demonstrated that the improved forward-type multiple-output is superior to its conventional counterpart in terms of steady-state and dynamic cross-regulation characteristics, and that the proposed multiple-output power supply has sufficiently precise multiple-output voltage regulation and a satisfactorily high power efficiency. >

Comparison of Multiple-Output DC-DC Converters Using Cross Regulation

A new multiple-output dc-dc converter is analyzed, in which the cross regulation is performed by the energy-storage reactor as well as the transformer. The steady-state and the dynamic characteristics of this converter are compared both theoretically and experimentally with those of the conventional one composed of the step-up-down type circuit. As the results of comparative analysis, it is revealed that this new converter is superior to the conventional one in the steady-state and the dynamic performances. Further, it is demonstrated experimentally that the cross regulation performance of this new multiple-output converter is less affected by the leakage flux in the energy-storage reactor, and also that this converter is very useful as a preregulator for the continuous series regulator in cases requiring a high degree of regulation of the multiple-output voltages.