The Infona portal uses cookies, i.e. strings of text saved by a browser on the user's device. The portal can access those files and use them to remember the user's data, such as their chosen settings (screen view, interface language, etc.), or their login data. By using the Infona portal the user accepts automatic saving and using this information for portal operation purposes. More information on the subject can be found in the Privacy Policy and Terms of Service. By closing this window the user confirms that they have read the information on cookie usage, and they accept the privacy policy and the way cookies are used by the portal. You can change the cookie settings in your browser.
For the excellent electrical performance, Gallium Nitride (GaN) new-type semiconductor devices are preferred in high voltage, high frequency and high power applications. However, GaN devices have low on-resistance and the loop layout requires low damping in high frequency loop. These both can lead to voltage and current oscillations under high frequency and even cause uncontrollable oscillations,...
GaN-FETs are attractive switching devices for their fast switching capability. However, they often suffer from the oscillatory false triggering, i.e. a series of self-sustaining repetitive false triggering induced after a fast switching. The purpose of this paper is to derive a design instruction to prevent this phenomenon. According to the previous study, the oscillatory false triggering was found...
Neutral point potential oscillation at low frequency is an important issue in four pole neutral point clamped converter since this leads to the extra voltage stress on the split DC-link capacitors. The detailed analysis indicates such oscillation is closely associated with the neutral point current at low frequency, so this paper explores their relationship, and presents the modulation techniques...
Due to the high switching speed of SiC MOSFET, the parasitic parameters and the low damping in the circuit, the turn-off overvoltage and oscillation of the freewheeling diode and SiC MOSFET are very severe. Based on the terminal impedances during the turn-off transition of the freewheeling diode and SiC MOSFET, the mechanism of the turn-off overvoltage and oscillation are analyzed and the suppressing...
A photovoltaic (PV) generator is one of the primary power sources in a DC micro-grid (MG). The power generated by PV systems may inject high-order transient harmonics and low frequency ripple into the DC MG, especially if a conventional widely used Perturbation and Observation (P&O) maximum power point tracker is employed. In this paper a novel active filtering approach is proposed to improve...
A novel modulation technique for single phase grid-tied inverter is proposed in this paper. In normal discontinuous current mode (DCM) operation, the output current becomes distorted due to the resonant between parasitic output capacitors of switching devices and inductor during zero current periods if no current control method is applied. This low frequency distortion can be improved in the boundary...
Current derivative based sensorless control methods, which falls under saliency tracking technique, is a promising new sensorless control methods for AC machines over a wide speed range, including zero speed. This method requires accurate current derivative measurement under different applied PWM voltage vectors. The accuracy of current derivative is affected by the high frequency oscillations which...
With switching transients as fast as 100 V/ns and a low threshold voltage of 1–2 V, GaN FETs in bridge-leg topologies are potentially vulnerable to crosstalk and the resultant unwanted partial turn-on, noise interference, and increased losses. Constant-strength gate drivers for GaN FETs limit switching speed to suppress crosstalk. In this work, active gate driving is shown to permit faster switching,...
Maximum power point tracking techniques play an important role in improving the efficiency of photovoltaic generation system. Among various schemes, the incremental conductance (INC) method is mostly discussed in literature because of its superb tracking ability in irradiance and temperature changes. However, because the conventional INC algorithms adopt a simple duty-cycle updating law that is mainly...
The stability problems of power electronics interfaced distributed generators with low inertia and damping can be well solved by the virtual synchronous generator technologies. However, when the grid voltages become unbalanced, oscillations in both the real and reactive power will arise with unbalanced voltages and currents of VSG being noticed. This paper proposed a flexible power control method...
A control strategy for a three-phase grid connected inverter with LCL filter based on Lyapunov energy function during unbalanced grid conditions is presented in this paper. To reduce complexity and number of variables the control strategy is accomplished in a stationary two phase reference frame. Dual second-order generalized integrator structure (DSOGI) is utilized to extract the positive and negative...
Silicon carbide (SiC) MOSFETs have been widely studied in high frequency applications. The switching performance, however, is limited with the existence of the parasitic elements. One critical issue is the susceptibility of the gate-source voltage to the parasitic elements, rendering the possibility of spurious operation of the SiC MOSFETs. This paper conducts comprehensive investigations on the impact...
Problems with power quality in the grid have gained a lot of attention recently due to rapid increase in the amount of grid-connected power converters. The converter should produce sinusoidal currents also during abnormal conditions, such as unbalanced grid voltages. Several methods, like the delayed signal cancellation-based method (DSC), have been proposed to alleviate the detrimental effect of...
This paper presents a separation method to discern broken rotor bar fault from low frequency load torque oscillation thorough radial leakage flux spectrums in induction motors (IMs). Broken rotor bar fault can usually be detected using classical motor current based analysis (MCSA), but it may not provide reliable results since its performance depend on motor topology, stator winding and load type...
Direct power control (DPC) is an attractive control method for three-phase pulse-width modulation (PWM) rectifiers, due to the merits of simple structure, quick dynamic response and little tuning work. However, conventional switching table based DPC presents relatively high power ripples and current harmonics, which is especially serious when the grid voltages are unbalanced. Introducing space vector...
Soft-switching self-tuning H-bridge converters for inductive power transfer (IPT) systems with resonant current regulation are introduced. The proposed converters are controlled based on an amplitude modulation technique for resonant converters to regulate the transferred power in an IPT system. The switching operations of the converters are synchronized to the resonance current of the IPT system...
Diversifying the role of grid side converters (GSC) associated with distributed generation (DG) may have a technical and economic impact. The increasing number of residential photovoltaic rooftop systems can be exploited by distribution network (DN) operators in order to support and improve the power quality of the grid without considerable further investment. GSC can support the grid during abnormal...
Sub-harmonic oscillation is a key factor causing instability for current-mode controlled single-inductor dual-output (SIDO) Buck converter. To inhibit the sub-harmonic oscillation of the converter and to extend its stable operating range, the ramp compensation technique is introduced in this paper. The discrete iterative map model of current-mode controlled SIDO Buck converter with ramp compensation...
Regenerative drives, also known as four-quadrant drives are integral part of many industrial applications ranging from wind power generation, elevators, escalators, pump jacks used in oil fields to centrifuges, etc. All regenerative converters need passive LCL filters to filter out PWM frequency components. One disadvantage of using an input LCL filter in front of regenerative converters is that they...
SiC-MOSFETs have attracting increasing attention because of their outstanding characteristics that contributes to high efficiency and high power density of power converters. However, compared to conventional Si-IGBTs, SiC-MOSFETs are susceptible to false triggering, because they tend to generate large switching noise due to ultrafast switching capability and have a lower threshold voltage in high...
Set the date range to filter the displayed results. You can set a starting date, ending date or both. You can enter the dates manually or choose them from the calendar.