Switching Oscillations Research Articles

Real-type test platform capacitor bank switching oscillation suppression strategy and switching device design

Real-type test platform capacitor bank switching oscillation suppression strategy and switching device design

Self-clamped P-shield 4H-SiC trench MOSFET for low turn-off loss and suppress switching oscillation

A novel 4H-SiC trench MOSFET with self-clamped P-region (SCP-MOS) is proposed. The breakdown voltage is boosted and switching oscillation is suppressed by introducing a lightly P-type doping concentration region (LP) and additional NCSL. P+ and NCSL form a new electric field modulation region that reduces the electric field at the bottom of the gate, resulting in a higher breakdown voltage for the device. Moreover, When VDS is small, the LP region links P-shield and P+ source region, the P-shield is clamped at a low potential, which effectively reduces the gate to drain capacitance (CGD). As VDS increases, the LP region is gradually depleted, causing the P-shield to transition into floating state, the potential in the P-shield region is raised. Consequently, the described characteristics facilitate achieving low turn-off losses and Surge voltage(VSurge). SCP-MOS has 32 % lower surge voltage compared to GP-MOS and 85 % lower turn-off loss compared to FP-MOS. Overall, SCP-MOS can obtain better EOFF-VSurge trade-off.

A Hybrid Physics-Based and Data-Driven Approach for Monitoring of Inverter-Fed Machine Stator Insulation Degradations Using Switching Oscillations

A Hybrid Physics-Based and Data-Driven Approach for Monitoring of Inverter-Fed Machine Stator Insulation Degradations Using Switching Oscillations

High-sensitive state perception method for inverter-fed machine turn insulation based on FrFT-Mel

Amidst the swift advancement of new power systems and electric vehicles, inverter-fed machines have progressively materialized as a pivotal apparatus for efficient energy conversion. Stator winding turn insulation failure is the root cause of inverter-fed machine breakdown. The online monitoring of turn insulation health can detect potential safety risks promptly, but faces the challenge of weak characteristics of turn insulation degradation. This study proposes an innovative method to evaluate the turn insulation state of inverter-fed machines by utilizing the fractional Fourier transform with a Mel filter (FrFT-Mel). First, the sensitivity of the high-frequency (HF) switching oscillation current to variations in turn insulation was analyzed within the fractional domain. Subsequently, an improved Mel filter is introduced, and its structure and parameters are specifically designed based on the features intrinsic to the common-mode impedance resonance point of the electrical machine. Finally, an evaluation index was proposed for the turn insulation state of inverter-fed machines. Experimental results on a 3kW permanent magnet synchronous machine (PMSM) demonstrate that the proposed FrFT-Mel method significantly enhances the sensitivity of turn insulation state perception by approximately five times, compared to the traditional Fourier transform method.

Vertically Stackable Ovonic Threshold Switch Oscillator Using Atomic Layer Deposited Ge0.6Se0.4 Film for High-Density Artificial Neural Networks.

Nanodevice oscillators (nano-oscillators) have received considerable attention to implement in neuromorphic computing as hardware because they can significantly improve the device integration density and energy efficiency compared to complementary metal oxide semiconductor circuit-based oscillators. This work demonstrates vertically stackable nano-oscillators using an ovonic threshold switch (OTS) for high-density neuromorphic hardware. A vertically stackable Ge0.6Se0.4 OTS-oscillator (VOTS-OSC) is fabricated with a vertical crossbar array structure by growing Ge0.6Se0.4 film conformally on a contact hole structure using atomic layer deposition. The VOTS-OSC can be vertically integrated onto peripheral circuits without causing thermal damage because the fabrication temperature is <400 °C. The fabricated device exhibits oscillation characteristics, which can serve as leaky integrate-and-fire neurons in spiking neural networks (SNNs) and coupled oscillators in oscillatory neural networks (ONNs). For practical applications, pattern recognition and vertex coloring are demonstrated with SNNs and ONNs, respectively, using semiempirical simulations. This structure increases the oscillator integration density significantly, enabling complex tasks with a large number of oscillators. Moreover, it can enhance the computational speed of neural networks due to its rapid switching speed.

Loop Conductance Adapting Methodology to Suppress Switching Oscillations in High-Frequency GaN-Based Circuits

Gallium nitride (GaN) devices have enormous potentials in electric vehicle (EV) applications. The trend of high frequency and high power density help increase EV mileage level greatly. However, due to the ultra-fast switching speed of the GaN devices and low damping level in the compact circuit, switching oscillations are prone to happen and sometimes even sustain, which affects the circuit stability heavily. In this research, loop conductance adapting methodology is proposed to solve this problem, which is inserting a loop conductance adapter (LCA) into the GaN-based circuit. The LCA can be in manifold forms and inserted into different positions. A modified negative conductance model is established, which is universal to all the forms and inserting positions. Based on the established model and a derived stability criterion, the optimized design method is proposed, with which the most appropriate LCA parameters could be calculated and the corresponding suppression effects could be predicted. The details of the design method are introduced with three typical LCA examples. All the theoretical achievements are verified with LTspice simulations and experiments. In addition, the three examples are compared with each other according to suppression effects and power losses. Suggestions about LCA inserting position selection are also proposed.

Double-ring high-frequency common-mode switching oscillation current sensor for inverter-fed machine winding insulation monitoring

Double-ring high-frequency common-mode switching oscillation current sensor for inverter-fed machine winding insulation monitoring

Long Short Term Memory Tracker‐Based Modified DC‐DC Converter for Power Quality Improvement in Grid‐PV Systems under Uniform and Partial Shading Environments

In previous era, coal and oil like non‐renewable resources were mostly used for power generation, thus causing a severe environmental problem as well as high economic. An intelligent maximum power point tracking (MPPT) system was proposed to overwhelm the above‐mentioned impacts, which tracks the maximum generation of photovoltaic (PV) under various atmospheric conditions. Moreover, a modified DC‐DC converter was introduced to low inrush current and switching oscillation. The proposed model working process was split into three steps: first, design the normal PV with a grid‐integrated power system. Second, create a dataset with the aid of a designed PV model, and finally, design an intelligent MPPT controller based on that dataset. The difference among the MPPT and PV voltage was fed to an optimal controller that generates an appropriate pulse signal of the modified DC‐DC converter. The proposed intelligent tracking system was analyzed under various circumstances like static, dynamic and combined shading conditions. The proposed model offers 99.5% efficiency and very low harmonics values like 0.15% current total harmonic distortion (THD) and 0.46% voltage THD. The outcome verifies that the intelligent MPPT approach performs well than that of the currently used controllers in solar power generation and conditioning systems.

Mathematical Model-Based Analysis and Mitigation of GaN Switching Oscillations

Mathematical Model-Based Analysis and Mitigation of GaN Switching Oscillations

Online Monitoring of Lithium-Ion Battery Impedance Using DC–DC Converter Self-Excited Switching Oscillations

Online Monitoring of Lithium-Ion Battery Impedance Using DC–DC Converter Self-Excited Switching Oscillations

A Switching Oscillation Suppression Method with Clamping Function and Quantitative Design for SiC MOSFETs

A Switching Oscillation Suppression Method with Clamping Function and Quantitative Design for SiC MOSFETs

An improved Power Cable Insulation Monitoring Method for Inverter-fed Machines Using Switching Oscillation Damping Feature

An improved Power Cable Insulation Monitoring Method for Inverter-fed Machines Using Switching Oscillation Damping Feature

Bifurcation analysis of complex switching oscillations in a Kerr microring resonator.

Microresonators are micron-scale optical systems that confine light using total internal reflection. These optical systems have gained interest in the past two decades due to their compact sizes, unprecedented measurement capabilities, and widespread applications. The increasingly high finesse (or Q factor) of such resonators means that nonlinear effects are unavoidable even for low power, making them attractive for nonlinear applications, including optical comb generation and second harmonic generation. In addition, light in these nonlinear resonators may exhibit chaotic behavior across wide parameter regions. Hence, it is necessary to understand how, where, and what types of such chaotic dynamics occur before they can be used in practical devices. We study here the underlying mathematical model that describes the interactions between the complex-valued electrical fields of two optical beams in a single-mode resonator with symmetric pumping. Recently, it was shown that this model exhibits a wide range of fascinating behaviors, including bistability, symmetry breaking, chaos, and self-switching oscillations. We employ here a dynamical system approach to perform a comprehensive theoretical study that allows us to identify, delimit, and explain the parameter regions where different behaviors can be observed. Specifically, we present a two-parameter bifurcation diagram that shows how (global) bifurcations organize the observable dynamics. Prominent features are curves of Shilnikov homoclinic bifurcations, which act as gluing bifurcations of pairs of periodic orbits or chaotic attractors, and a Belyakov transition point (where the stability of the homoclinic orbit changes). In this way, we identify and map out distinctive transitions between different kinds of chaotic self-switching behavior in this optical device.

Online Monitoring of Cable Insulation Degradation for Inverter-Fed Machine System Using PWM Switching Oscillations

Online cable condition monitoring is a reliability enhancement technique for inverter-fed machine systems, which requires high sensitivity with quantitative assessment capability to detect the incipient insulation degradation as early as possible. This article presents a noncontact cable condition monitoring method by utilizing the inverter's self-excited high-frequency (HF) PWM switching oscillations. As an HF resonance, the switching oscillation is sensitive to the small change of degrading cable insulation capacitance. First, the characteristic mode, i.e. the HF differential-mode, is selected for sensitive cable condition monitoring from the multi-modal switching oscillation in an inverter-fed machine system. Then, an online condition monitoring scheme is proposed, including the framework, the noncontact HF oscillation current sensor, and the indicator(s) of cable insulation condition estimated from the amplitude-frequency features of the characteristic oscillation mode. Finally, experimental work was carried out on a 20 m cable-connected 3-kW inverter-fed machine test rig and the results demonstrate the good sensitivity and robustness of the method.

Analysis and Optimization of High-Frequency Switching Oscillation Conducted CM Current Considering Parasitic Parameters Based on a Half-Bridge Power Module

Analysis and Optimization of High-Frequency Switching Oscillation Conducted CM Current Considering Parasitic Parameters Based on a Half-Bridge Power Module

A Switching Oscillation Event-Triggered Switch Fault Detection Method for SiC DC–DC Converter

Switch fault detection is critical for the safety and reliability of a SiC dc–dc converter, which is however difficult by directly comparing the PWM voltage and the gate signal due to the harsh electromagnetic environment and ultrahigh switching frequency. To address the challenges, a novel method is proposed to detect and diagnose the switch fault using the converter PWM high-frequency (HF) switching oscillation. First, the switching event status in a SiC dc–dc converter is captured from the HF switching oscillation current in a noncontact way. Then, the switch fault is detected and diagnosed by checking the signal integrity of the switching events with no need for a gate signal. Finally, a switching oscillation event-triggered switch fault detection system is developed including the HF oscillation sensor, switching event capture circuit, and switch fault detection and diagnosis unit. Experimental work is carried out and the results demonstrate the performance of the method with high safety up to MHz.

A novel inductively coupled RLC damping scheme for eliminating switching oscillations of SiC MOSFET

AbstractSevere switching oscillations of SiC MOSFET seriously affect its efficient and reliable application. Herein, a novel inductively coupled RLC damping scheme is proposed to eliminate switching oscillations. Distinctive from existing RLC resonators, the setting that the resonant frequency of the secondary RLC damping is equal to that of the power loop is abandoned. Additionally, prior‐art analytical techniques of RLC resonators are based on seeking the peak impedance, which considerably undermines its suppression effect. First, a two‐port network is linearized from switching oscillations, where the characteristic equations are deduced. Then, parametric regions where the switching oscillations can be eliminated are determined by actively assigning poles via the root locus method. Consequently, the damping effect of the proposed scheme, as well as the resulted switching losses, shows its superiority over the state‐of‐the‐art snubbers. The proposed scheme is favourable in practical applications since it is less insensitive to parasitics enabling selection of snubber resistors with higher power ratings. It also avoids unusual temperature rise resulted by snubber losses due to oscillation suppression in the power loop as snubber losses are transferred to the secondary circuit. Theoretical analysis and experimental comparisons are conducted to verify the effectiveness of the proposed scheme.

Investigation on Optimal Switching Oscillation Suppression for SiC MOSFET by Inductively Coupled Damping

SiC MOSFET has been revolutionizing power electronics but producing more severe switching oscillation due to its inherent faster switching speed and lower damping characteristics. The inductively coupled damping approach is promising since no additional circuit element is inserted into the power processing loop. Thus, reliability of this inductively coupled fashion is higher compared to other existing snubbers. However, prior-art analytical design techniques are mainly based on scrutinizing the peak impedance and only discussed under a certain specific coupling, which limited its suppression effect. In this article, by viewing from the terminals of both upper and lower SiC MOSFETs in a half-leg circuit, two-port networks are linearized from switching oscillation and developed to deduce the exact characteristic equations. Then, the optimal snubber configuration along with two key parameters, i.e., the inductance factor and the secondary resistance, are determined via the root locus method. It is revealed that the damping effect of RL in the strong coupling region is even better than that of the secondary RLC resonator. What is more, applying the coupled RL damping circuit could not only remarkably dampen the switching oscillations, but also greatly lower switching losses. Finally, discussion on selecting the optimal snubber parameters is illustrated in detail.

Core loss measurement and comparative analysis for soft magnetic materials under complex non-sinusoidal excitations

With the advancement of wide-bandgap power devices, the power electronics equipment is developing toward higher switching frequencies and more complex switching modes in recent years. Accurate prediction of the core loss for magnetic components has been emphasized as the excitations of magnetic materials varying depending on the operating mode of the power supplies. Therefore, this paper presents the results of an extensive core loss study performed on nanocrystalline alloy (FT-3KL), amorphous alloy (1K101) and ultra-thin oriented silicon steel (GT-50). Firstly, an automatic setup for core loss measurement of soft magnetic materials fed by a full-bridge inverter based on silicon carbide (SiC) MOSFET is proposed. Then, the effects of switching oscillations from the inverter and the characteristic parameters of complex non-sinusoidal excitations on the core loss are analyzed comparatively. The core loss shows different regular distributions with the change of each characteristic parameter of excitations respectively. However, the regular distributions will be influenced by the high-frequency switching oscillations, which makes the prediction of core loss more complicated. This paper can provide a reference for the development of high-precision core loss model and performance optimization of power electronics equipment.

A Suppression Method for Gate-Source Voltage Oscillation With Clamping Function for GaN Devices

Gallium nitride (GaN) devices are generally more prone to severe switching oscillations than Si <sc xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">mosfets</small> due to their fast switching speeds. Different from Si and SiC <sc xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">mosfets</small> , GaN devices typically have a lower maximum gate voltage rating. Taking the Efficient Power Conversion Corporation series as an example, the gate drive voltage is usually 5 V, but the maximum voltage rating is 6 V. Therefore, GaN devices are more susceptible to damage from gate-source voltage oscillation. In this letter, a gate drive circuit with a clamping function is proposed to suppress gate-source voltage oscillation. The adopted method can not only clamp the gate voltage of the GaN device near the drive voltage to protect the device, but also does not affect the switching speed of the device. The proposed method mainly uses some passive components that make the circuit design simpler compared with other active gate driver methods. Finally, the effectiveness of the proposed method is verified by experiments.