Influence Of Parasitic Parameters Research Articles

Study on the Resonance Characteristics and Active Damping Suppression Strategies of Multi-Inverter Grid-Connected Systems Under Weak Grid Conditions

When a multi-inverter grid-connected system is influenced by the parasitic parameters of LCL-type inverters and the impedance of the connected system’s lines, its resonance characteristics become more complex and difficult to predict. For LCL-type multi-inverter grid-connected systems, a mathematical model that considers the effects of parasitic parameters and line impedance has been established, leading to the derivation of the system’s Norton equivalent circuit and a general expression for the inverter output current. The resonance characteristics of multi-inverter grid-connected systems composed of inverters with the same and different parameters were analyzed under the influence of parasitic parameters and line impedance. To suppress the resonance in multi-inverter grid-connected systems and address the issue of traditional PI control not meeting grid requirements for LCL-type grid-connected inverters, a strategy combining superhelical sliding mode control with active damping was adopted. To verify the practical performance of the adopted resonance suppression strategy in complex environments, a grid-connected system model containing two LCL-type inverters was constructed using the MATLAB/Simulink software platform, followed by simulation analysis. The simulation results strongly confirm the feasibility and effectiveness of the adopted resonance suppression strategy, considering the effects of parasitic parameters and line impedance. This strategy demonstrates significant suppression effects in addressing resonance issues caused by parasitic parameters and line impedance, effectively enhancing the quality of grid-connected electrical energy.

Improved Design of a SiC MOSFET Gate Drive with Crosstalk Suppression Capability

For high-frequency switching applications, silicon carbide (SiC) devices are more suitable than silicon-based devices, which is conducive to improving the efficiency and power density of power electronic equipment. However, as the switching frequency increases, the influence of parasitic parameters on the switching characteristics of devices becomes increasingly apparent. When SiC metal-oxide-semiconductor field-effect transistors (MOSFETs) are applied in bridge circuits, the crosstalk problem easily occurs with the complementary conduction of upper and lower transistors, which seriously limits the promotion of SiC MOSFETs. However, the existing crosstalk suppression drive circuit tends to increase the switching loss, switching delay, and control complexity; therefore, a gate drive with crosstalk suppression capability is proposed. In this paper, the gate drive has two features: a negative voltage to shut down the SiC MOSFET; and an adjustment of the gate-source equivalent impedance. To accomplish this goal, the mechanism of crosstalk voltage generation is analyzed. Furthermore, the operation principle of the gate drive is analyzed, and the parameters of the gate drive are designed. Eventually, the proposed gate drive is verified by an LTspice simulation and experimental platform. The results prove that the gate drive can suppress the crosstalk voltage without affecting the switching speed.

Method for automatic antenna matching with transmitter output stage

This work is devoted to the study of automatic antenna tuning units of the short-wave range. Devices of narrowband matching based on discrete sets of reactive elements are considered. A classification of the most frequently used automatic matching methods has been made. The advantages and disadvantages of each method are analyzed. Examples of using different approaches in commercially available devices are given. Particular attention is paid to the calculation method of matching, as the most promising for use in modern communications. Assumptions are made about the reasons for its rare use in serial devices. Circuits have been developed to simulate the influence of parasitic parameters of the components of the matching circuit and the body of the tuning unit on the resulting standing wave ratio when using this method. Based on the simulation results, conclusions were drawn about the reasons for the low quality of the calculation method. As an alternative, a new method of automatic tuning is proposed, combining the advantages of computation and search methods, which is based on modeling the search process using a simulation model. The conditions for its application in automatic antenna tuning units are determined. Acomparative analysis of the features of both the known methods of automatic tuning and the newly proposed one ismade.

Influence of network parameters on the accuracy of control and diagnostics of resistance welding

The influence of parasitic parameters of the power supply network (active resistance and inductance) on the accuracy of resistance welding diagnostics is estimated. Evaluation of the effectiveness of various control algorithms when operating under conditions of fluctuations in the supply voltage is performed. The methodic for determining the parasitic parameters of the network is presented. Keywords: resistance welding, automation, control and diagnostics. KlimovTGU@yandex.ru

Analysis of noise-reduction filter design by computer modelling

The article describes the principles of evaluating the design disadvantages of a noise-reduction filter. The characteristics of the developed equipment are influenced by many parameters, such as the inhomogeneity of the components used, the parasitic interference introduced by them, and noise induced from structural elements and external sources. At the same time, the search for and elimination of the reasons for the discrepancy between the parameters of the designed products requires more and more expenses during the development stages. That is why the problem of modeling equipment with parameters close to real ones and under conditions different from laboratory ones is urgent. To assess the influence of the above factors in the Qucs 0.0.19 program, a noise suppression filter was simulated, the introduced attenuation of which did not meet the requirements of the design documentation (this problem was identified due to the use of modern measuring equipment at the stage of serial production). A family of curves is constructed that describe the behavior of the circuit for various values of the parameters of the elements. Equivalent circuits were used to assess the influence of parasitic parameters. The effect of noise induced by structural elements was approximated using parallel connected transformers in short circuit mode. The simulation was carried out in the frequency range from 100 Hz to 1 GHz. As a result of the conducted research, it was obtained: taking into account the parasitic parameters of the elements leads to a significant change in the form of the ideal frequency response of the noise suppression filter; the value of the capacitance of the pass capacitor in the considered frequency range does not make a significant contribution to the attenuation introduced by the filter; in the low-frequency region, the magnitude of the inductance of the coils has the greatest influence on the output characteristic of the filter; in the high-frequency region, the radiating properties of structural elements begin to appear, the influence of which on the attenuation introduced by the filter is significant.

A Low-Cost High-Performance Voltage Sensing Circuit With Proactive Parameter Design Compensation Network for SiC MOSFETs

Wide bandgap semiconductors show superior material properties enabling silicon carbide (SiC) metal-oxide-semiconductor field-effect transistors (MOSFETs) present good features on its switching speed and withstand voltage. However, the high voltage and fast switching characteristics of SiC MOSFETs also put forward new requirements for voltage measurement, that is, high bandwidth under high voltage conditions. This article proposes a new voltage divider structure and a proactive parameter design compensation network to build high voltage and high bandwidth voltage sensing circuit. This structure utilizes the characteristics that the same resistor has the same parasitic capacitance to meet the high frequency constraints of the voltage sensing circuit. The influence of parasitic parameters and load parameters on circuit performance is analyzed in detail, which provides a basis for the compensation network design. By combining the proposed voltage sensing circuit with an appropriate proactive parameter design load effect compensation network (PDCN), the withstand voltage rating of the low-voltage and high-bandwidth voltage probes can be extended to required levels. Different from other existing methods, PDCN can actively design the compensation circuit parameters and provide the optimal parameters of the compensation circuit. This lead to a smaller input capacitance than the state of the art commercial voltage probes, which will help to obtain better performance when measuring high-speed switching voltage. The performance of the voltage measurement is experimentally verified and compared by SiC-based double pulse test (DPT) circuits.

Research on Losses of PCB Parasitic Capacitance for GaN-Based Full Bridge Converters

The utilization of wide band-gap semiconductor devices provides the possibility of higher switching frequency and power density for power converters. However, the influence of parasitic parameters becomes more significant. It deteriorates the converter performance and leads to extra loss. In this article, the extra loss caused by the parasitic capacitance of printed circuit boards (PCBs) is studied. The mechanism is explained, and the model of full bridge topology with PCB parasitic capacitance is proposed as an example. Both the capacitance in power loops and control circuits are considered in the proposed model. Besides the capacitive loss in power loops, losses are also introduced by the capacitive coupling between the power and control circuits due to the potential pulsation of the control ground. This potential pulsation is analyzed and the calculation method of corresponding losses is presented. The formation of PCB parasitic capacitance is analyzed in detail and corresponding layout optimization methods are proposed. Theoretical analyses are verified on a gallium nitride based full bridge prototype with calorimetric loss measurement. The comparison of calculated and measured losses is presented, which shows a switching loss deviation of 26% without the consideration of parasitic capacitance and a 40% reduction on the extra losses after the proposed optimization.

Algorithm for Indirect Measurement of the Parameters of the Passive Complex Conductivity of a Two-Terminal Circuit in a Multipole Electrical Circuit

An algorithm is proposed for indirect measurement of the parameters of the passive complex conductivity as a separate two-terminal circuit and also as a two-terminal device located in one of the branches of a multipole passive triangle-type electrical circuit without needing to separate it into separate two-terminal circuits. A structural diagram is presented for a microprocessor device to measure the parameters of the passive complex conductivity of a two-terminal device located in one of the branches of a multipole passive triangle-type electrical circuit. The algorithm for the indirect method of measuring the parameters of the passive complex conductivity of the two-terminal circuit is based on the theory of matrices and nondirectional graphs. Equations are obtained for calculating the modulus and components of the passive complex conductivity of a two-terminal circuit located in a multipole triangle-type electrical circuit. The proposed algorithm avoids the methodological error owing to the influence of parasitic parameters. Results are presented from an experimental test of the algorithm for indirect measurement of the conductivity of a two-terminal circuit.

Improved Phase Shift Control for SiC-MOSFET Based Resonant Switched-Capacitor Converter with Parasitics Consideration

In this article, the resonant switched-capacitor converter (RSCC) is applied to the auxiliary power system of electric locomotive to improve its efficiency and power density. Phase shift control is generally applied to the RSCC for voltage regulation. But the dead time and parasitic parameters impose the negative effects on the switching transit, the resulted hard-switching process may cause extra switching loss. An optimized soft- switching realized method is proposed under phase shift control. First, transient analysis of resonance is carried out by state trajectory, and steady-state characteristics are discussed. Then, the influence of parasitic parameters on resonant current and output power is discussed. Moreover, the dead-time effect and soft-switching condition are analyzed; therefore, a high-efficiency control strategy with zero-voltage switching is proposed. Experimental results show that the proposed optimization control strategy can improve the efficiency up to 99.4%.

Influence of Parasitic Parameters on DC–DC Converters and Their Method of Suppression in High Frequency Link 35 kV PV Systems

Photovoltaic (PV) power generation has shown a trend towards large-scale medium- or high-voltage integration in recent years. The development of high-frequency link PV systems is necessary for the further improvement of system efficiency and the reduction of system cost. In the system, high-frequency high-step-up ratio LLC converters are one of the most important parts. However, the parasitic parameters of devices lead to a loss of zero-voltage switching (ZVS) in the LLC converter, greatly reducing the efficiency of the system, especially in such a high-frequency application. In this paper, a high-frequency link 35 kV PV system is presented. To suppress the influences of parasitic parameters in the LLC converter in the 35 kV PV system, the influence of parasitic parameters on ZVS is analyzed and expounded. Then, a suppression method is proposed to promote the realization of ZVS. This method adds a saturable inductor on the secondary side to achieve ZVS. The saturable inductor can effectively prevent the parasitic elements of the secondary side from participating in the resonance of the primary side. The experimental results show that this method achieves a higher efficiency than the traditional method by reducing the magnetic inductance.

1.6‐2.6 GHz continuous Class‐F power amplifier with gain and power‐added efficiency flatness enhancement by negative feedback structure

AbstractThis article studies the feasibility of applying negative feedback structure in continuous Class‐F power amplifiers to improve the gain and efficiency flatness. The operation principle of the negative feedback structure under small and large signal input states is presented. The gain and efficiency are increased at high frequency part and decreased at low frequency by introducing the negative feedback structure, and the flatness is improved. Multiharmonic bilateral pull is used to obtain the optimum impedances, to reduce the interaction between source and load side, and the influence of parasitic parameters. A highly flatness amplifier with the negative feedback structure is designed operating at 1.6‐2.6 GHz by using a Cree GaN HEMT CGH40010H device. The measurement results show a gain flatness of 1.1 dB, and a power‐added efficiency flatness of 9%.

Influence of Parasitic Parameters on Switching Characteristics of GaN Power Devices

Influence of Parasitic Parameters on Switching Characteristics of GaN Power Devices

Influence of Parasitic Parameters on Switching Characteristics and Layout Design Considerations of SiC MOSFETs

Influence of Parasitic Parameters on Switching Characteristics and Layout Design Considerations of SiC MOSFETs

Instability Analysis and Oscillation Suppression of Enhancement-Mode GaN Devices in Half-Bridge Circuits

This paper analyzes the problem of instability in enhancement-mode gallium nitride (GaN) transistors based half-bridge circuits. The instability may cause sustained oscillation, resulting in overvoltage, excessive electromagnetic interference (EMI), and even device breakdown. GaN devices operate in the saturation region when they conduct reversely during the dead time. Under the influence of parasitic parameters, the GaN-based half-bridge circuit exhibits positive feedback under certain conditions, thus, resulting in sustained oscillation. A small-signal model is proposed to study this positive feedback phenomenon. Like the second-order under-damped system, damping ratio is defined to determine the system's stability. Based on the model, the influence of circuit parameters on instability is investigated and guidelines to suppress the oscillation are given. Reducing the common-source inductance, increasing the gate resistance of the inactive switch or connecting a diode in parallel to the inactive switch are some effective ways to suppress the oscillation. Finally, the analyses are verified by both simulation and experiment.

Influence of Parasitic Inductances on Switching Performance of SiC MOSFET

Compared to the silicon power devices, silicon carbide device has shorter switch time. Hence, as a result of the faster transition of voltage (dv/dt) and current (di/dt) in SiC MOSFET, the influence of parasitic parameters on SiC MOSFET’s switching transient is more serious. This paper gives an experimental study of the influence of parasitic inductance on SiC MOSFET’s switching characteristics. Most significance parameters are the parasitic inductances of gate driver loop and power switching loop. These include the SiC MOSFET package’s parasitic inductance, interconnect inductance and the parasitic inductance of dc link PCB trace. This paper therefore focuses on analysis and comparison of different parasitic parameters under various operation conditions in terms of their effect on overvoltage, overcurrent and switching power loss.

AN INDUCTION SENSOR FOR MEASURING CURRENTS OF NANOSECOND RANGE

Purpose. A current meter based on the principle of electromagnetic induction is designed to register the current flowing in the rod lightning. The aim of the article is to describe the way of increasing the sensitivity of the converter by means of their serial communication. Methodology . The recorded current is in the nanosecond range. If compared with other methods, meters based on the principle of electromagnetic induction have several advantages, such as simplicity of construction, reliability, low cost, no need in a power source, relatively high sensitivity. Creation of such a meter is necessary, because in some cases there is no possibility to use a shunt. Transient properties of a meter are determined by the number of turns and the constant of integration. Sensitivity is determined by measuring the number of turns, the coil sectional area, the core material and the integration constant. For measuring the magnetic field pulses with a rise time of 5 ns to 50 ns a meter has turns from 5 to 15. The sensitivity of such a meter is low. When the number of turns is increased, the output signal and the front increase. Earlier described dependencies were used to select the main parameters of the converter. It was based on generally accepted and widely known equivalent circuit. The experience of created earlier pulse magnetic field meters was considered both for measuring the magnetic fields, and large pulse current. Originality. Series connection of converters has the property of a long line. The level of the transient response of the meter is calculated. The influence of parasitic parameters on the type of meter transient response is examined. The shown construction was not previously described. Practical value. The results of meter implementation are given. The design peculiarities of the given measuring instruments are shown.

An influence of parasitic parameters on electromagnetic disturbance emission in voltage converters

In this paper it is estimated an influence of parasitic parameters of elements in converters of different topologies on a spectral components of conducted electromagnetic interference. Scalability of obtained results allows to estimate expected levels of electromagnetic interferences (EMI) from considered converters types, and hence, develop more efficient interference-suppression filters (ISF) for switching-type power supplies (STPS) with less development cost. Results are obtained for frequency band of 0–30 MHz.