This paper discusses selected problems regarding a high-frequency improved current-fed quasi-Z-source inverter (iCFqZSI) designed and built with SiC power devices. At first, new, modified topology of the impedance network is presented. As the structure is derived from the series connection of two networks, the voltage stress across the SiC diodes and the inductors is reduced by a factor of two. Therefore, the SiC MOSFETs may be switched with frequencies above 100 kHz and volume and weight of the passive components is decreased. Furthermore, additional leg with two SiC MOSFETs working as a bidirectional switch is added to limit the current stress during the short-through states. In order to verify the performance of the proposed solution a 6 kVA laboratory model was designed to connect a 400 V DC source (battery) and a 3£400 V grid. According to presented simulations and experimental results high-frequency iCFqZSI is bidirectional – it may act as an inverter, but also as a rectifier. Performed measurements show correct operation at switching frequency of 100 kHz, high quality of the input and output waveforms is observed. The additional leg increases efficiency by up to 0.6% – peak value is 97.8%.
Conceptions of analogue electronics circuit based on a multiple-input floating gate field-effect transistor MOS (MIFGMOS) have
been presented. The simple add and differential voltage amplifiers with one and two MIFGMOS transistors and multiple-input operational amplifiers with their application have been proposed. One of them was used for the realisation of a controlled floating resistor. Results of circuit simulations in SPICE programme using the simple substitute macromodel of MIFGMOS transistor have been shown.
The paper presents an overview of a method of nanosecond-scale high voltage pulse generation using magnetic compression circuits. High voltage (up to 18 kV) short pulses (up to 1.4 μs) were used for Pulsed Corona Discharge generation. In addition, the control signal of parallel connection of IGBT and MOSFET power transistor influence on system losses is discussed. For a given system topology, an influence of core losses on overall pulse generator efficiency is analysed.
In this paper, a low power highly sensitive Triple Metal Surrounding Gate (TM-SG) Nanowire MOSFET photosensor is proposed which uses triple metal gates for controlling short channel effects and III–V compound as the channel material for effective photonic absorption. Most of the conventional FET based photosensors that are available use threshold voltage as the parameter for sensitivity comparison but in this proposed sensor on being exposed to light there is a substantial increase in conductance of the GaAs channel underneath and, thereby change in the subthreshold current under exposure is used as a sensitivity parameter (i.e., Iillumination/IDark). In order to further enhance the device performance it is coated with a shell of AlxGa1-xAs which effectively passivates the GaAs surface and provides a better carrier confinement at the interface results in an increased photoabsorption. At last performance parameters of TM-SG Bare GaAs Nanowire MOSFET are compared with TM-SG core-shell GaAs/AlGaAs Nanowire MOSFET and the results show that Core-Shell structures can be a better choice for photodetection in visible region.
The paper presents a concept of a control system for a high-frequency three-phase PWM grid-tied converter (3x400 V / 50 Hz) that performs functions of a 10-kW DC power supply with voltage range of 600÷800 V and of a reactive power compensator. Simulation tests (in PLECS) allowed proper selection of semiconductor switches between fast IGBTs and silicon carbide MOSFETs. As the main criterion minimum amount of power losses in semiconductor devices was adopted. Switching frequency of at least 40 kHz was used with the aim of minimizing size of passive filters (chokes, capacitors) both on the AC side and on the DC side. Simulation results have been confirmed in experimental studies of the PWM converter, the power factor of which (inductive and capacitive) could be regulated in range from 0.7 to 1.0 with THDi of line currents below 5% and energy efficiency of approximately 98.5%. The control system was implemented in Texas Instruments TMS320F28377S microcontroller.