Supercapacitors can store a million times more energy per unit mass or volume compared to electrolytic capacitors. Due to their low internal resistance, they are capable of driving or absorbing pulsative high currents. Over the last quarter, century supercapacitor (SC) manufacturers have developed several families of mass-scale devices with high-power density and a longer cycle life that helped the end-users to improve their energy storage systems and products. Today, there are three common device families, namely, (i) symmetrical double-layer capacitors (EDLCs), (ii) hybrid capacitors with a lithium electrode, and (iii) battery capacitors based on pseudo capacitance concepts. This review paper compares these families and provides an overview of several state-of-the-art applications in electric vehicles (EVs), microgrids, and consumer electronics.

To overcome short-term input energy fluctuations, and to offer complete 24-hour energy solutions based on renewable resources such as solar and wind, energy storage devices are mandatory. A relatively new storage family is the supercapacitor (SC), which were developing rapidly over the last 15 years, which are yet to compete with rechargeable batteries. Today with three different commercially available supercapacitor families developing rapidly, with 1 to 70 000 F per single cell, at least one of them are reaching the specific energy of lead-acid batteries. All new families of supercapacitors have charge/discharge life cycles of several orders larger than rechargeable battery chemistries, their usage in energy storage systems are rapidly advancing. Supercapacitor assisted converters are a new family of very low-speed converters, where a power electronic building block is combined with a supercapacitor bank to achieve high end-to-end efficiency, with the added advantage of DC-UPS capability within the converter. The paper provides an overview of the new Supercapacitor Assisted Loss Management theory applied to supercapacitor assisted converters, with practical examples of implementation useful in renewable energy systems such as SC assisted low dropout regulator, SC assisted LED, SC assisted server rack power architecture, and SC assisted wide input inverter.

All electrical and electronic devices require access to a suitable energy source. In a portable electronic product, such as a cell phone, an energy storage unit drives a complex array of power conversion stages to generate multiple DC voltage rails required. To optimize the overall end-to-end efficiency, these internal power conversions should waste minimal energy and deliver more to the electronic modules. Capacitors are one of the main component families used in electronics, to store and deliver electric charges. Supercapacitors, so called because they provide over a million-fold increase in capacitance relative to a traditional capacitor of the same volume, are enabling a paradigm shift in the design of power electronic converter circuits. Here we show that supercapacitors could function as a lossless voltage-dropping element in the power conversion stages, thereby significantly increasing the power conversion stage efficiency. This approach has numerous secondary benefits: it improves continuity of the supply, suppresses voltage surges, allows the voltage regulation to be electromagnetically silent, and simplifies the design of voltage regulators. The use of supercapacitors allows the development of a novel loss-circumvention theory with applicability to a wide range of supercapacitor-assisted (SCA) techniques. These include low-dropout regulators, transient surge absorbers, LED lighting for DC microgrids, and rapid energy transfer for water heating.

Approximate efficiency of a linear regulator is given by the ratio of regulated output voltage to input voltage. Higher voltage difference between the input and the output means a lower efficiency due to heavy losses in the series power semiconductor. Supercapacitor‐assisted low dropout regulator (SCALDO) is an emerging linear DC–DC converter technique, where a supercapacitor (SC) is used to reduce the voltage drop across the series transistor in a linear regulator where the SC acts as a lossless dropper. The circuit operates at a very low frequency decided by the size of the SC. An efficiency multiplication factor such as 1.33, 2, or 3 is achieved depending on the configuration. This study presents the essentials of its generalised theory, few prototype implementations, and a discussion on SCALDO properties. Typical efficiencies of 12–5 and 5–1.2 V linear regulators are around 42 and 24%, respectively. When SCALDO prototypes are built, the authors achieve respective end‐to‐end efficiencies of 79–81 and 58–73%. A loss analysis summary and further developments of the novel technique are also provided, in addition to a discussion to indicate that this is not a variation of the switched capacitor converters.

Energy harvesting from energy sources is a rapidly developing cost-effective and sustainable technique for powering low-energy consumption devices such as wireless sensor networks, RFID, IoT devices, and wearable electronics. Although these devices consume very low average power, they require peak power bursts during the collection and transmission of data. These requirements are satisfied by the use of energy-storage devices such as batteries or supercapacitors (SCs). Batteries offer significantly higher energy density but are subject to regular replacement, thermal runaway risk, and environmental concerns. On the other hand, SCs provide over a million-fold increase in capacitance compared to a traditional capacitor of the same volume. They are considered as the energy-storing devices that bridge the gap between conventional capacitors and batteries. They also offer fast charging times, a long lifecycle, and low equivalent series resistance (ESR). Most importantly, they are capable of handling the high transient currents produced by energy harvesters and provide a stable power source for external loads. This study encompasses a brief exploration of the three fundamental SC types. Then, the discussion delves into the integration of SCs into energy harvesting applications. The collective knowledge presented aims to guide future research endeavors fostering the development of novel energy harvesting systems using SCs.

Globally, renewable energy-based power generation is experiencing exponential growth due to concerns over the environmental impacts of traditional power generation methods. Microgrids (MGs) are commonly employed to integrate renewable sources due to their distributed nature, with batteries often used to compensate for power fluctuations caused by the intermittency of renewable energy sources. However, sudden fluctuations in the power supply can negatively impact battery performance, making it challenging to select an appropriate battery energy storage system (BESS) at the design stage of an MG. The cycle count of a battery in relation to battery stress is a useful measure for determining the general health of a battery and can aid in BESS selection. An accurate digital replica of an MG is required to determine the required cycle count and stress levels of a BESS. The Digital Twin (DT) concept can be used to replicate the dynamics of the MG in a virtual environment, allowing for the estimation of required cycle numbers and applied stress levels to a BESS. This paper presents a Microgrid Digital Twin (MGDT) model that can estimate the required cycle count and stress levels of a BESS without considering any unique battery type. Based on the results, designers can select an appropriate BESS for the MG, and the MGDT can also be used to roughly estimate the health of the currently operating BESS, allowing for cost-effective predictive maintenance scheduling for MGs.