The majority of power losses in solar inverter systems are driven by the root mean square (RMS) DC current in the input loop and the voltage stress imposed on inverter components. The Supercapacitor-Assisted Inverter (SCA-inverter) technique based on the Supercapacitor-Assisted Loss Management (SCALoM) concept, reduces these losses by partitioning the load of a single central inverter into an even number of smaller inverters, integrated with a set of supercapacitor (SC) modules. This approach effectively doubles the inverter system’s input voltage range without having to increase the voltage rating of the components, while halving the input RMS current by a factor of two. This paper presents an experimental efficiency validation of a proof of concept prototype (PoC) of a four-SCA-inverter system and a single inverter delivering the same cumulative power output upto 200W. The proposed technique allows the use SC modules to provide uninterruptible DC power supply (UPS) functionality without having to rely on conventional battery packs.

This paper presents the development of a new Matlab mosfetmodel specifically designed for RLC circuits. The key contribution is the formulation of a novel equation that accurately captures the device behavior across subthreshold, above-threshold regions and at threshold point, addressing limitations in existing models. The developed model treats themosfetas a variable resistance element, with the resistance changing dynamically at each instant, enabling the solution of differential equations governing the RLC circuit. Curve fitting and refinement were conducted based on experimental results, leading to a close match between the simulations and experimental data. The model was tested with triangle, sinusoidal and quadrilateral gate voltages, and the simulation results show good match with the experimental data, demonstrating the model’s accuracy. It provides a straightforward way to predict performance, making it easier to refine and optimize the design gate voltage before physical implementation. This work provides a solid foundation formosfetmodeling in oscillatory RLC circuits, which can be applied to a wide range of power electronics applications.

Over the past several decades many researchers have attempted developing DC circuit breaker techniques, recognizing that a DC current loop does not have voltage or current zero crossings across the contact terminals, in comparison with an AC circuit where voltage and current waveforms carry two zero crossings per each cycle. All DC circuit breaker design efforts are based on several primary techniques such as (i) mechanical (ii) solid state and (iii) hybrid. However, commercially useful techniques or prototype development has been limited to mechanical only approach with the adoption of 3 phase AC circuit breakers where three separate contacts are placed in series to share arc energy. Solid state and hybrid design approaches require DC power supplies, transistor driver stages and synchronization circuits which makes the prototype development very cumbersome. As a uniquely different approach, authors have started working on supercapacitor assisted techniques for arc energy management and this article presents corresponding preliminary findings with some experimental evidence.

Supercapacitor assisted loss management (SCALoM) concept has laid the theoretical foundation to develop high efficiency power converters for renewable energy systems using supercapacitors as lossless voltage droppers and energy buffers. SCALoM theory is applicable to inverter combinations in reducing overall losses, mainly occurring in the input loop, including losses in the DC bus capacitor.Supercapacitor assisted (SCA) multi-inverter technique reduces the voltage stress on the internal components of inverters enabling the use of more efficient lower voltage rated components. A summary of the theoretical foundations with reference to previous works on the topic is presented first. The four-SCA-inverter technique discussed in this paper extends the input voltage range of an inverter system by two times and reduces the input loop current by two times. The preliminary results obtained from the first experimental prototype of the 700W four-SCA-inverter system coupled with four identical 250F supercapacitor modules switched at low frequencies (less than 0.02 Hz), show up to 2.53% of efficiency gain at the inverter end. Additionally, proposed technique provides unquantified efficiency gains by reducing the ripple currents in the system, functioning as an energy buffer. Development of a high power capable SCA-inverter prototype is in progress.

High-voltage pulse generators are useful in many applications such as transient surge simulators, electric fence energizers, and transcranial magnetic stimulation (TMS) systems. Traditionally they are based on a high-voltage DC power supply with or without voltage multipliers for raising the voltage to several thousand volts. In contrast to these complex and costly approaches, we use a pre-charged supercapacitor followed by a step-up transformer and associated output circuitry to develop an inexpensive and flexible high-voltage pulse generator for applications in transcranial magnetic stimulation. Our new approach is to use the high-power delivery capability of commercial supercapacitors. In this work, we explore the advantages of different waveforms applied to the MOSFET associated with the secondary stage of the circuit topology and how they affect the final pulse shape.

DC circuit breakers have become an essential protection element for DC buses in renewable energy and DC microgrid systems. Given that there are no zero crossings in a DC power supply compared to an AC waveform, arc extinguishing is a difficult process in DC circuit breakers. Solid state switches are proposed in solving this problem, but their cost is generally unaffordable in general applications, except for marine, military and aviation etc. Hence, commercial and mass-produced DC breakers are modified versions of AC breakers. This paper details different passive component options for absorbing the energy in the electric arc/plasma, including the use of supercapacitors.

SCASA is a new supercapacitor assisted surge protector technique whose goal is to reduce component count in surge protectors while achieving higher surge-withstand capability. Basic topology was developed based on a semi-experimental basis, during the first stage leading to patents and a successful commercial implementation. This paper summarises a numerical analysis applied to the basic circuit to compare and validate its performance with experimental results using a lightning surge simulator and LTSpice simulation. Noiseken LSS6230 was used as the test gear to do the testing according to IEEE C62.4X standards and UL 1449 test procedure. This comparison is used as the basis for further improvement of SCASA topology to withstand higher energy and increased surge repetition.

Supercapacitor (SC) assisted low dropout regulator (SCALDO) is a very low-frequency DC-DC converter technique, with high end-to-end efficiency, where the load receives a high slew rate capable low noise output of a linear regulator. This technique can be easily extended with a transformer isolated input stage to achieve the 48-V DC rack power architecture proposed by Google recently. One specific advantage of this new design approach is the two-stage DC-UPS capability by over-sizing the SC bank. In this new SCALDO-derived technique with transformer isolation, by inserting an SC in the input side of the converter, energy transfer towards the load side occurs at a higher frequency, in a combination of forward and flyback modes to reduce the overall volume of the converter. The paper details the magnetics design aspects of the technique providing experimental results of a proof of concept prototype.

Typical solar powered DC-microgrids (DCMG) employ rechargeable batteries for energy storage. In order to extract and deliver the maximum power out from the PV array to the load, maximum power point tracking (MPPT) solar charge controller is mandatory. With the commercial supercapacitor (SC) devices available in the market, new converter techniques with SC energy storage are possible for DCMG systems. The SCALED converter is such a technique where the rechargeable battery bank is replaced by a supercapacitor bank. However, if a SC bank is used as the sole energy storage, existing MPPT schemes are no longer appropriate since the storage bank acts as near ideal capacitor instead of a rechargeable battery pack. This is due to the fact that a capacitor bank retains energy within its electrostatic field, compared to the electrochemical reaction related back EMF of a battery pack. This paper presents the theoretical analysis to validate the above hypothesis.

Energy efficiency of power converters used in computer server farms is a major issue today since these facilities consume huge amounts of energy on a continuous basis. In 2016, Google introduced a 48 V rack power architecture at the Open Computing Project (OCP) summit to replace 12 V, and announced their plans to shift towards 48 V DC rails with DC-UPS. This was with the main target of reducing ohmic losses in the DC-distribution by 16 times and transformer losses by 30%. Compared to well-developed switching converter techniques, a new linear high efficiency RFI/EMI free DC-DC converter technique, namely SCALDO, has the potential to be used for these 48 V DC server power supplies. This paper presents analytical and simulation details of an electrically isolated, 48 V DC, 20 A extended-SCALDO based design. Experimental validation of this technique has been established by developing a proof of concept prototype, a scaled down 30-to-6-V DC converter. The paper highlights the advantages of combining the fly-back and forward modes similar to a switching converter, for charging a supercapacitor bank which acts as energy reservoir, where the final 48 V DC rail is regulated by a simple SCALDO converter extended to supply 20 A, and achieving DC UPS capability by over-sizing the supercapacitor.

In configuring energy-efficient renewable energy systems, rechargeable batteries are typically used with maximum power point tracking (MPPT) based DC-DC converters. With the commercial supercapacitor (SC) devices available in three different forms namely (i) symmetric electrical doubled layer capacitors (EDLC) (ii) hybrid and (iii) capa-batteries, where device cycle-life is exponentially larger than rechargeable batteries, new converter techniques with SC energy storage are possible for DC Microgrid systems. This paper presents the preliminary concept of a new and commercially-useful SC-based LED powering technique, currently under development as the SC assisted LED (SCALED) technique. Challenges of developing this technique which can be extended into the powering of DC powered electrical appliances is presented with the theory and early experimental validations carried out in a sea-port based industrial location.

Electrical physics text book theory tells us that charging a capacitor is much less efficient than replenishing the energy in a discharged electro-chemical battery. If a fully discharged capacitor is pumped with a charge of Q coulombs, it stores 1/2QV while dissipating the same amount of energy in the loop resistance. However, if the same charge is pumped into a re-chargeable electrochemical cell of voltage V the energy stored in the cell is QV, while the wasted energy is determined by the loop resistance and the voltage difference across the resistance. If a rechargeable battery pack is to be replaced by a supercapacitor module, this difference could seriously affect the design of power converters required, since the power converter should stop charging at a certain point to avoid overcharging the capacitor bank. However, if a useful resistive load such as heater, DC-DC converter, inverter or a lamp load is used as a part of the loop resistance in a capacitor charging loop, a significant part of this loss can be recovered. One example of this is in the supercapacitor assisted low drop-out regulator (SCALDO) technique. This paper will detail the concept of circumvention of RC loop charging loss, theoretically quantifying the same in a generalized circuit, demonstrating how this can be applied in completely novel circuit topologies such as the supercapacitor assisted LED (SCALED) converter. The paper will provide experimental results of selected SCALDO implementations and early results of SCALED technique to support this theory.

AC voltage regulators, an important family of power conditioners, are intended to reduce line-voltage fluctuations of AC mains at customer premises. Typical designs are based on automatic tap changers, motor-driven variacs, thyristor-based systems, ferro-resonant systems and solid-state versions. Solid-state regulators typically rely on high frequency switching, so have significant RFI/EMI problems, while ferro-resonant regulators are bulky, have high no-load power consumption and waveform defects. Thyristor-driven designs are light in weight, but also have waveform defects. Motor-driven variacs are slow-responding, while automatic tap changers create spikes. A linear design using an array of serially connected transistors was developed in late 1980's to address these issues, and to achieve rapid output response without requiring thyristors, high-frequency switching or mechanical systems [1], [2]. We have built on these ideas to develop an AC voltage regulator for consumer use, with a power output ranging from 500 to 3000 W. A multi-primary-winding transformer design was originally proposed, but was found to be uneconomical due to manufacturing costs. The simple approach is to combine two standard step-down transformers. The viability of this approach demonstrated with practical results for a scaled down prototype which can be scaled up to a full 230 V, 2 kVA commercial product. Energy efficiency is optimized by minimizing the losses in the transistor array.

Charging a capacitor is different to supplying power to a resistive load. With an ideal voltage source a fully discharged capacitor takes five time constants to reach its full charge. From a current source this depends on the current rating. Therefore a capacitor charger can be characterised by the associated total charge. Due to supercapacitors' (SC) large time constant fast charging becomes problematic. The charging topology presented uses a coupled inductor and a voltage source rated higher than the capacitor rated voltage to charge a SC bank divided in to two parts. One part is charged by the higher voltage source and the other by the energy stored in the inductor. Power factor correction can be achieved without using any additional components. This paper presents results from a 3000 joule proof of concept prototype.

A supercapacitor-assisted low-dropout regulator (SCALDO) technique has been developed previously to improve the end-to-end efficiency of linear regulators based on low-dropout regulators. To implement this technique in a high-current application such as a voltage regulator module (VRM), it is necessary to reduce the number of low-speed switches used in SCALDO topologies. A preliminary prototype of a modified SCALDO version has been built with commercially available low-dropout regulators to prove the concept of reduced-switch SCALDO. One limitation of this reduced-switch SCALDO prototype was the unwanted discharge of supercapacitors via body-diode of low-dropout regulators. Experimental results indicate that the reduced-switch SCALDO can be further developed for application to VRM by suitably designing a high-current low-dropout regulator. This paper presents the theoretical aspects of the reduced-switch topology, a new approach to avoid the low-dropout regulator body-diode effect on supercapacitors, and a method to optimize the control circuits. The preliminary results of a custom-designed 1.5 V, 2 A discrete low-dropout regulator and a 3.5-to-1.5 V reduced-switch SCALDO converter are presented.

With the transformer less direct AC mains rectification adopted in many AC-DC converters for processor based products, many electronic components in off-the-line switchmode power supplies are vulnerable to common-mode transients. With the predictions in the International Technology Roadmap for Semiconductors, VLSI devices are currently progressing towards feature sizes around 22 nm, with sub 1 V DC power supply requirements and equivalent noise voltages close to the DC rail values. These two scenarios make state-of-the-art systems seriously vulnerable to lightning and other power transients, and better transient protection systems are required by the power conversion electronics. In a research project to predict the propagation of transients within the power conversion interfaces, accurate models for nonlinear surge protection devices have been developed. This paper highlights the numerical simulations done with the help of MATLAB to investigate transient propagation through an IEC61000-4-5 specified category “B” protection unit. The accuracies of the simulations are confirmed by experimental validations using a lightning surge generator.

Relationships between spiking-neuron and rate-based approaches to the dynamics of neural assemblies are explored by analyzing a model system that can be treated by both methods, with the rate-based method further averaged over multiple neurons to give a neural-field approach. The system consists of a chain of neurons, each with simple spiking dynamics that has a known rate-based equivalent. The neurons are linked by propagating activity that is described in terms of a spatial interaction strength with temporal delays that reflect distances between neurons; feedback via a separate delay loop is also included because such loops also exist in real brains. These interactions are described using a spatiotemporal coupling function that can carry either spikes or rates to provide coupling between neurons. Numerical simulation of corresponding spike- and rate-based methods with these compatible couplings then allows direct comparison between the dynamics arising from these approaches. The rate-based dynamics can reproduce two different forms of oscillation that are present in the spike-based model: spiking rates of individual neurons and network-induced modulations of spiking rate that occur if network interactions are sufficiently strong. Depending on conditions either mode of oscillation can dominate the spike-based dynamics and in some situations, particularly when the ratio of the frequencies of these two modes is integer or half-integer, the two can both be present and interact with each other.