Current Issue : October - December Volume : 2019 Issue Number : 4 Articles : 5 Articles
This paper proposes a new technique and design methodology on a transformer-based Class-E\ncomplementarymetal-oxide-semiconductor (CMOS) power amplifier (PA)with only one transformer and\ntwo capacitors in the load network. An analysis of this amplifier is presented together with an accurate\nand simple design procedure. The experimental results are in good agreement with the theoretical\nanalysis. The following performance parameters are determined for optimum operation: The current\nand voltage waveform, the peak value of drain current and drain-to-source voltage, the output power,\nthe efficiency and the component values of the load network are determined to be essential for optimum\noperation. The measured drain efficiency (DE) and power-added efficiency (PAE) is over 70% with\n10-dBm output power at 2.4 GHz, using a 65 nm CMOS process technology....
In this paper, a direct power control (DPC) technique is proposed for matrix converter-fed\ngrid-connected doubly fed induction generators (DFIGs). In contrast to what has been investigated\nin the past for direct torque control (DTC) or DPC of matrix converter-fed DFIGs, the active and\nreactive powers are regulated in a fixed switching frequency using indirect space vector modulation\n(ISVM) technique. Hence, designing input filters for matrix converters (MCs) becomes convenient.\nIn addition, the reactive component of input side of MC is controlled which leads to reduction of\ndistortion in grid current waveform. Also, an extensive discussion is addressed for nonlinear voltage\nerrors of MC that may cause inaccurate power control. Simulation results done in MATLAB/Simulink\nshow the effectiveness of the proposed method....
In this article the problem of modelling a switching process of Insulated Gate Bipolar\nTransistors (IGBTs) in the SPICE software is considered. The new form of the considered transistor\nmodel is presented. The model includes controlled voltage and current sources, resistors and voltage\nsources. In the model, influence of temperature on dc and dynamic characteristics of the IGBT is\ntaken into account. A detailed description of the dynamic part of this model is included in the article\nand some results of experimental verification are shown. Verification is performed for a transistor\nIRG4PC40UD by International Rectifier. The presented results of computations and measurements\nshow clearly influence of temperature on on-time and off-time, and additionally switching energy\nlosses are observed. Moreover, the results of investigations performed with the use of the new model\nare compared to the results of computations performed with classical models of the considered device\ngiven in the literature. It is proved that the new model makes it possible to obtain a better match to\nthe results of measurements than the considered models described in the literature....
Nowadays, wind turbines based on a doubly fed induction generator (DFIG) are a commonly\nused solution in the wind industry. The standard converter topology used in these systems is the\nvoltage source inverter (VSI). The use of reverse-blocking insulated gate bipolar transistor (RB-IGBT)\nin the current source inverter topology (CSI), which is an alternative topology, opens new possibilities\nof control methods. This paper presents a novel power control system for a DFIG supplied by a CSI.\nThe authors propose to use multi-scalar DFIG state variables. A nonlinear control method realized by\nfeedback linearization was used to control the active and reactive powers of the generator. In the\nfeedback linearization controls, the nonlinear DFIG model was taken into account. In the control\nsystem structure, classical proportional-integral controllers were used. The control variables were\nthe output current vector components of the CSI. Such approach was named the â??current controlâ?.\nThe proposed control method is characterized by good dynamic properties which, combined with\nthe inverter properties in the rotor circuit, allow to increase the quality of the energy transferred\nto the grid by the generator. In the simulation tests, the correctness of the decoupling of the active\nand reactive power control loops, the dynamics of controlled power changes, and the change of the\nmachine operating range resulting from the increase of the rotational speed of the generator shaft\nwere controlled. The simulation studies also evaluated the impact of changes in the value of the\npassive elements of the system on the operation of the generator system. Characteristic operating\nstates of the generator system were analyzed using computer simulations....
Nowadays, marine electromagnetic method is a geophysical method which can effectively explore natural gas hydrate (NGH)\nresources. This method acquires seafloor structure and distribution laws of mineral resources by transmitting high-power\nelectromagnetic waves to the seafloor, and its detection depth relies on the intensity of transmitted electromagnetic waves. At\npresent, marine electromagnetic transmitter is not proper for transmission of high-power electromagnetic waves, and therefore, a\nnovel controlled-source circuit of soft switching three-level marine electromagnetic transmitter is proposed in this paper, one\nstep-down winding is added at the secondary side of high-frequency transformer in series connection with a linear inductor,\nasymmetric phase-shift PWM control is used, and soft switching of controlled-source circuit within the overall power range is\nrealized. A detailed analysis of the operation process and circuit characteristics is given, and finally, a prototype is designed.\nExperimental results indicate that this circuit is of wide ZVS range and high efficiency, and it meets requirements for deep-sea\ndetection of high-voltage power supply transmitter....
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