The paper presents the design key issues for a plasma generation method. A Class E Power Amplifier is used to generate plasma at 13.56MHz with a variable load implemented with an air coil and a variable capacitor. Class E amplifier represents a mean of high efficiency power amplification. Ideal amplifiers reach 100% efficiency and by proper filtering and tuning even the real circuit efficiency can be only 5% lower. By measuring the input impedance of the matching network the resistance, the voltage and the power of the plasma torch can be estimated. In order to do that, two matching networks were designed; the first one is partially compensated and the second is completely compensated. The problems that can appear at a capacitive tuning in air and Argon atmosphere are also presented. Finally, the steps needed to design the plasma generator with class E power amplifier and air coils are described.

Supercapacitors are components for energy storage, dedicated for applications where both energy and power density are needed. Even if their energy density is ten times lower than the energy density of batteries, supercapacitors offer new alternatives for applications where energy storage is needed. We have done an experimental bench and we have measured the voltage across a supercapacitor in a constant current charge/discharge cycle. Using these measurements and a mathematical algorithm we have proposed an electrical model for the supercapacitor, and we have determined the parameters of the model also.

The increasing complexity of the electronic devices and the challenges involved in satisfying the needs of higher power and energy determine us to pay an important attention on supercapacitors behaviour study. Even if their energy density is about ten times lower than the energy density of the batteries, supercapacitors offer new alternatives for applications where energy storage is needed. This paper discusses one simplified PSpice model for supercapacitors. The proposed method for computing the parameters of the equivalent electrical circuit is based on experimental data achieved in different test conditions. The improved parameter identification method used provides a satisfying accuracy if the profiles of the charge/discharge/self-discharge of the supercapacitors are known.

In applications where very precisely frequencies and fast switching speed are required the best solution consists in a DDFS circuit. This solution is very attractive in all digital systems because this architecture can provide fast tuning speed and coherent phase. In this paper a direct digital frequency synthesizer implemented on a FPGA (field programmable gate array) chip is presented. Comparatively with other component types (e.g. microprocessor), FPGA chips permit higher speeds for specific applications. The architecture used for DDFS circuit is a classic DDFS, described in the first paragraph of this paper, and short reports of the implementation are presented to underline the advantages of FPGA. This kind of circuit is easy to be implemented on a programmable gate array, and uses only a few resources of the device.

The synergy between batteries and capacitors has been growing, to the point where supercapacitos may soon be almost as indispensable to portable electricity as batteries are now. One very important parameter of a supercapacitor is the Equivalent Series Resistance (ESR). The energy that can be stored in a supercapacitor depends on ESR, so we intend to measure that parameter. Our tests were made on a 350F supercapacitor, 14 V, produced by Econd Ltd. We have two methods: the first consist in evaluating ESR by constant current discharge, and the second method consists in a dynamic discharge cycle at a constant current. After measurements and some mathematical evaluations a real value of ESR is proposed.

This paper presents the status regarding electric vehicles (EVs) and public charging stations managed by Cluj-Napoca City Hall. The types of charging stations and the quantity of the used energy were stated. The behavior of EV owners in charging their vehicles was also studied. The presented work proposes an extension of the EV charging infrastructure to support current and future EV owners. Simulations were carried out in Simulink to create an overview of the existing infrastructure. The simulation results showed the amount of greenhouse gas (CO₂ emissions) reduced by using EVs. An estimated number of kilometers traveled with EVs was calculated by tracking the loads in all public charging stations.