The purpose of this paper is to carry out a comprehensive study of supercapacitor in the application of power electronics. According to the practical demand and feasibility of power electronics, the modelling, voltage management and topology of supercapacitor-based power system have been discussed. Further more, in order to study the terminal behaviour of supercapacitor and voltage balancing strategy for the application of power electronics, a test bench based on HP-VEE has been built. The measurements on supercapacitor's capacitance, ESR (Equivalent serial resistance) and the consistency of a group of serial supercapacitors, concerning practical application have been suggested. As an example, Maxwell's BCAP0120 supercapacitors have been selected for a 1.5kW hybrid supercapacitor- fuel cell power system. Tests have been carried out and the results show that the ESR is higher and the capacitance is lower compared with the values supplied by manufacturers; and the consistency of them is good, thus the voltage initialization strategy can be used for voltage balancing.

Study of supercapacitor in the application of power electronics

In the design of a parallel resonant induction-heating system, choosing a proper capacitance for the resonant circuit is quite important since both output-power maximization and capacitor heat loading should be considered. The temperature rise often blows up the water-cooled capacitors in high-power induction heaters or reduces the lifetime of capacitors significantly. This paper, therefore, presents a method of finding an optimal capacitance that maximizes the output power while considering the capacitor loss at the same time. To count the effect of the capacitor heatup, an equivalent series resistance is included in the model. Based on the equivalent circuit model, the output power and the capacitor loss are obtained as the functions of capacitance, and an optimization technique is applied treating the capacitance as a control variable. The effectiveness of the proposed method is verified by simulations and experiments. Equivalent series resistance (ESR), induction heater, optimal selection, parallel resonant circuit.

An Optimal Selection of Induction-Heater Capacitance Considering Dissipation Loss Caused by ESR

A small capacitor-based DC power supply was designed using a combination of bootstrapped and non-bootstrapped converter topologies. This design focused on start-up under load, low voltage performance, maximum energy-density and utilization of surface mount components. These were integrated onto a board mounted on configurations of 50 F, 2.5 V ultracapacitors.

Integrated capacitor and converter package

In the design of a parallel resonant induction heating system, choosing a proper capacitance for the resonant circuit is quite important. The capacitance affects the resonant frequency, output power, Q-factor, heating efficiency and power factor. In this paper, the role of equivalent series resistance (ESR) in the choice of capacitance is significantly recognized. Without the effort of reducing temperature rise of the capacitor, the life time of capacitor tends to decrease rapidly. This paper, therefore, presents a method of finding an optimal value of the capacitor under voltage constraint for maximizing the output power of an induction heater, while minimizing the power loss of the capacitor at the same time. Based on the equivalent circuit model of an induction heating system, the output power, and the capacitor losses are calculated. The voltage constraint comes from the voltage ratings of the capacitor bank and the switching devices of the inverter. The effectiveness of the proposed method is verified by simulations and experiments.

An optimal selection of induction heater capacitance considering dissipation loss caused by ESR

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Control of ultra-capacitor based power electronic converters.

The double-layer capacitor is a recent innovation that combines high surface area electrode materials with the high capacitance per unit area of the chemical double layer. Commercially available devices with a capacitance of 1500 F are now available (Matsushita, 1992). This improvement in rated capacitance has presented opportunities for the use of double layer capacitors in high power and/or high energy storage applications (Burke, 1995 and Hall, 1995). This paper examines the discharge performance characteristics of several capacitors, including both aqueous and organic electrolyte devices. A useful simplified model is assumed for the double layer capacitor, consisting of an equivalent series resistance (ESR) and a capacitor in series. Values for these two parameters are determined in this investigation under various discharge conditions, along with peak current during short circuit conditions.

R.M. Nelms

Papers

Discharge characteristics of high energy storage double layer capacitors