Low Switching Losses Research Articles

Switching Performance Analysis of Vertical GaN FinFETs: Impact of Interfin Designs

This article studies the switching performance of vertical GaN power FinFETs and proposes new interfin designs to improve it. The interfin region has been found to be an important limiting factor for FinFET switching performance. The time taken to (dis)charge the dielectric parasitic capacitances and drift layer in the interfin regions severely limits the device turn-(on)off speed. Three new interfin designs are proposed, based on reduced fin-to-fin spacing, oxide full-filling (FF), and split-gate (SG) structures. The 1.2-kV, 80-mΩ vertical GaN FinFETs with these designs were evaluated by a well-calibrated device-circuit mixed-mode technology computer-aided design (TCAD) simulation. Both the reduced-fin-spacing structure and the oxide FF reduce the dielectric parasitic capacitances, but only lead to small reduction (less than 10%) in switching losses. Much better improvement is obtained with the SG structure, which removes the gate metal in the interfin region and exposes the drift layer to the field lines from the source metal. During the turn-(on)off of the transistor with a SG structure, the drift layer underneath the interfin gap region is (dis)charged by a combination of the drain-to-source and gate currents, leading to shorter switching times and lower switching losses. By utilizing the SG structure, simulations predict a 58% improvement in the switching figure-of-merit and 38% lower switching losses in 1.2-kV vertical gallium nitride (GaN) power FinFETs. These results provide key understanding and design guidelines for power FinFETs. Finally, an 800-V buck converter using a 1.2-kV GaN FinFET half-bridge module is simulated, showing excellent efficiency when operating at a multi-MHz frequency and revealing the requirement for device thermal management. This highlights the great potential of vertical GaN power FinFETs for future high-frequency medium-voltage power applications.

A level shifted asymmetric duty cycle controlled half-bridge series resonant LED driver configuration

ABSTRACT This paper proposes an efficient LED lamp converter circuit incorporating dimming feature and multiple lamp independent control. The converter consists of a half-bridge resonant converter in series with a DC source. This converter operates at 200 kHz. Soft switching is employed with resonant power conversion. With modulation of the low frequency pulse width, the dimming feature is incorporated. The proposed configuration provides lower voltage stress for switching devices as well as lower switching losses resulting in increased efficiency. It is possible to independently control the current of each lamp. For two lamps operating in parallel with a total power of 25 W, a laboratory prototype has been designed. It can be used in residential applications. The proposed circuit is presented with detailed operation of the circuit, simulation and experimental results.

A Multicarrier-PWM Scheme Along With a Reconfigurable Buck Converter Imitating Multiple Times Higher Switching Frequency

This letter proposes a novel multicarrier pulsewidth modulation scheme and a reconfigurable dc-dc converter topology, which produces multiple times higher effective switching frequency than the actual switching frequency of the power devices. The reconfigurable topology incorporates multiple switches in series, and their gate pulses are generated using multiple modified and phase-shifted carrier waves. These switches operate alternately to multiply the operating frequency. Since the devices do not actually have to operate at high switching frequency, slower and cheaper power devices can be used. The resulting smaller filter requirement and cheaper power devices make the overall system compact and cost-effective. Moreover, the total switching losses in the proposed converter are distributed among a larger number of devices, which results in low switching loss per device. Consequently, the heatsink requirement comes down. The proposed scheme helps in developing a high-frequency switch mode power supplywithout the use of wide bandgap power devices. Nevertheless, combining the proposed scheme with silicon carbide and gallium nitride-devices can give tremendous enhancement in the operating frequency. The proposed concept has been explained and analyzed in detail and compared with the traditional schemes. Simulation and experimental results validate the concept.

A High-Efficiency Three-Level ANPC Inverter Based on Hybrid SiC and Si Devices

Silicon carbide (SiC) devices have excellent performance, such as higher switching frequency and lower switching loss compared with traditional silicon (Si) devices. The application of SiC devices in inverters can achieve higher efficiency and power density. In recent years, the production process of SiC devices has become more mature, but the cost is still several times that of traditional Si devices. In order to balance cost and efficiency, replacing only some of the Si devices with SiC devices in a topology is a better choice. This paper proposed a high-efficiency hybrid active neutral point clamped (ANPC) three-level inverter which has only two SiC devices and the other devices are Si devices. A specific modulation strategy was applied to concentrate switching losses on the SiC devices and reduce the on-state loss through parallel operation during freewheeling intervals. Theoretical efficiency curves and experimental verification of the proposed hybrid scheme with Si-only and SiC-only schemes were carried out.

Efficiency comparison of capacitive wireless power transfer for different materials

<p>This paper describes the application of several types of materials to act as capacitive plates in a Capacitive Power Transfer (CPT) system. In general, the efficiency of CPT system is greatly influenced by the coupling capacitance which is varied by distances and permittivity values. Thus this paper intended to compare the performance of CPT system in terms of the output efficiency for several types of capacitive plates. To be specific, copper plate, zinc, and aluminium are used in this work to act as coupling plates to the CPT system. The CPT system in this work applied class E inverter as it has lowest switching losses among its competitors, i.e. class D and class F. The work is validated through experimental setup of CPT system in which copper material provides the best efficiency of the system.</p>

Reflected Wave Phenomenon in SiC Motor Drives: Consequences, Boundaries, and Mitigation

In voltage source inverter-based motor drives, the fast switching speeds of the power devices result in the reflected wave phenomenon. Besides the overvoltages at the motor end, there are overcurrents at the inverter end. The overvoltages increase stress on the motor and cable insulation, and the overcurrents affect the power devices. Wide bandgap (WBG) devices have lower switching losses and enable high switching frequencies. However, the reflected wave phenomenon is more pronounced in converters using WBG devices and could potentially increase the switching losses. This article presents a comprehensive analysis of the influence of the reflected wave phenomenon on the switching characteristics of SiC devices in motor drives. Notably, the effect of undamped reflected waves and different cable lengths on both the inverter end and motor end is studied. The analysis and experiments in this article uncover that, depending on the switching instance, the undamped reflected wave causes up to a 30% increase or up to a 15% decrease in the switching losses. A 12% reduction in the switching losses is observed with no cable to up to 20-m long cable. The last part of the article presents the design tradeoffs involved in designing a dv/dt filter. Five different dv/dt filters are compared in terms of their impact on the switching losses, dv/dt at the load, filter loss, and damping time of the reflected wave. The L filter and the RLC filter have around a 9% reduction in switching losses. The L filter suffers from increased damping time and higher reflected wave magnitude, making it unsuitable for high switching frequency applications. Overall, L // R filter offers the lowest filters losses with a 6% reduction in switching loss, making it more suitable for WBG devices-based high-speed motor drives.

Series-Connected Current-Source Inverters: f SW = 60 Hz

Pulsewidth-modulated series-connected current-source inverters (SC-CSIs) are a good candidate for high-voltage applications. In this letter, a new SC-CSI with a switching frequency of 60 Hz is proposed. Compared with the conventional one, the proposed inverter features lower switching losses, higher dc current utilization, and reduced passive component sizing.

Harmonic Elimination of a PV Based Cascaded H-bridge Seven Level Inverter for Induction Motor Drive

In today’s era, reliable and good quality power is an essential requirement in industry, which can be supplied by inverters at medium and high power. Most of the appliances in the industry require high power or medium power for their operation. Power electronics devices such as inverters work on medium voltage and high power and are suitable for industrial applications and renewable particularly Photovoltaic (PV) integration. Multilevel inverters are more superior to conventional inverters because of lower harmonics and switching losses, but as the number of levels increases, complexity also increases. Therefore, maintaining the harmonics at lower level and lesser complexity of multilevel inverters is a challenge for researchers. In this research paper, a novel approach for implementation of seven level cascaded H- bridge configuration of multilevel inverter using direct current source and photovoltaic panels has been demonstrated. The basic working principle of seven level cascaded hybrid bridge inverter, pulse width modulation techniques and total harmonic distortion are explained through simulations in Matlab and Xilinx 14.3 software and the same is experimentally validated through FPGA controller based Spartan 6. The designed seven level inverter results in lower total harmonic distortion with lesser complexity when used to connect PV panels.

Eighteen-Step Inverter: A Low-Loss Three-Phase Inverter for Low-Cost Standalone Applications

In this article, a new three-phase seven-level inverter is proposed with a new switching algorithm. This algorithm has eighteen switching steps. The switching algorithm is implemented on a topology, which consists of three legs and each leg has four switches. The switching frequency for six switches is the same as output wave frequency. The proposed algorithm results in lower switching losses, higher efficiency, and lower number of switches. This inverter has low cost and low volume, and is especially suitable for standalone applications. In addition, a modified pulsewidth modulation (PWM)-based version is proposed for eighteen-step switching algorithm to reduce the filter size and increase the controllability of the output waveform. Simulation and experimental results demonstrate good performance of the proposed inverter.

High Step-Up DC–DC Converter With Zero Voltage Switching and Low Input Current Ripple

A high step-up dc-dc converter is proposed in this article. With magnetic-coupling-based voltage multiplier technique, the proposed converter achieves high voltage gain and low switch voltage stress. Also, due to a boost inductor at the input, continuous input current is obtained, which is beneficial for battery, fuel cell, and photovoltaic applications. Moreover, zero voltage switching of the mosfets is achieved, leading to low switching losses. Furthermore, zero dc bias of the coupled inductor is realized, resulting in small magnetic size and low core losses. The operation principles, performance analysis, and design considerations of the proposed converter are discussed. A prototype with 40-V input and 400-V output has been developed to verify the theoretical analysis.

Sawtooth-Carrier-Based Pulsewidth Modulation Method for Quasi-Z-Source Inverter With Zero-Voltage-Switching Operation to Reduce Harmonic Distortion and Inductor Current Ripple

This article proposes a novel sawtooth-carrier based pulsewidth-modulation (SCPWM) method for quasi-Z-source inverter (qZSI) with the zero-voltage-switching (ZVS) operation to reduce the total harmonic distortion (THD) and inductor current ripple. The conventional variable-duty pulsewidth-modulation (VDPWM) method has been being used for qZSIs because it causes the low switching loss. However, this method has the limitation not only to improve the THD of output current but also to reduce the size of inductor when it is applied to the qZSI. To figure it out, the proposed SCPWM method uses the sawtooth-carrier signal while keeping the benefit from the use of variable duty. In particular, the ZVS operation occurs whenever the edge of sawtooth-carrier signal is located in the time interval of shoot-through state. This allows to increase the carrier frequency of qZSI without any additional switching loss. Thus, both the THD of output current and the inductor current ripple can be reduced while keeping the high efficiency of system. The operating principle of the proposed SCPWM method is first explained in detail. Thereafter, its performance is mathematically analyzed and compared with that of conventional VDPWM method. Finally, its practical effectiveness is verified by the hardware experimental test.

Grid integrated photovoltaic system with fuzzy based maximum power point tracking control along with harmonic elimination

ABSTRACTEfficient extraction and conversion of solar power is an important research area in the field of renewable energy integration. Although, literature is enriched with different power extraction, conversion, and harmonics elimination techniques but still there are problems of maximum power point tracking (MPPT) under partial shading conditions, photovoltaic (PV) mismatching, power fluctuation in steady‐state condition, and higher total harmonic distortion (THD) value. The article has two manifolds. First, it proposes a fuzzy embedded MPPT controller to extract the maximum available PV power under time‐varying environmental conditions. For that, it utilizes seven linguistic variables and fuzzy sets along with 49 rules base to have reduced power fluctuation and power losses in a steady‐state condition, and fast tracking under time‐varying temperature and solar irradiance condition. The performance of the proposed fuzzy‐logic control (FLC)‐49 rules base is compared with FLC‐25 rules and perturb & observe based MPPT controllers. Second, for fulfilling the load demands with lower switching losses and THD, particle swarm optimization (PSO) based selective harmonic elimination (SHE) technique is applied on a cascaded half‐bridge multilevel inverter. SHE technique utilizes switching angles, which are found by solving the nonlinear transcendental equations obtained by Fourier series expansion of stepped output voltage waveform. For that, the proposed research preferred meta‐heuristic techniques of PSO over the classical techniques because of their high convergence rate, short run time, less complexity, and ability to obtain lower THD.

Event-Triggered Model Predictive Control for Power Converters

In this letter, an event-triggered model predictive control (ET-MPC) method for power converters is presented. In the proposed method, the model predictive control (MPC) scheme is triggered only when the state of the converter exceeds a preset threshold; otherwise, the MPC scheme is suspended and the control signal is held as constant. Therefore, compared with the conventional MPC with finite control set (FCS-MPC), the ET-MPC method has the advantages of less computational burden and less switching actions, which contribute to lower switching losses, while ensuring satisfactory regulation performance. A buck converter prototype is adopted to validate the performance of ET-MPC. The results from the comparison with FCS-MPC demonstrate the effectiveness of the proposed ET-MPC method.

Comparative Study of 2SiC&4Si Hybrid Configuration Schemes in ANPC Inverter

Compared with traditional silicon (Si) power devices, silicon carbide (SiC) devices have attracted extensive attention due to their excellent characteristics. In recent years, the manufacturing process of SiC devices has become more mature, but the cost is still high. Therefore, replacing only some of the Si devices with SiC devices in a topology is a better choice to achieve higher system efficiency while considering costs. This paper studies the hybrid configuration schemes consisting of two SiC devices and four Si devices (2SiC&4Si) in ANPC three-level inverter. Two hybrid 2SiC&4Si topologies are proposed. In order to make full use of the low switching loss characteristics of SiC devices in hybrid topologies, specific modulation strategies are applied to concentrate switching losses on SiC devices. Based on the 2SiC&4Si hybrid ANPC topologies, three efficient SiC&Si hybrid configuration schemes are derived. In this paper, the theoretical comparison and experimental verification of the efficiency and loss distribution of the three hybrid schemes are carried out.

A Single Stage Common Ground Three-Level PV Inverter With Integrated Power Decoupling

In this paper, a T-type common ground transformer-less single phase inverter with dynamic swing of the dc-link voltage is presented for photovoltaic (PV) application. The topology is a combination of a bi-directional, partial-power-processing boost stage and an asymmetric half-bridge inverter stage along with a T-branch. It takes advantage of the three-level switching states with reduced voltage stress on the main switches to achieve lower switching loss and almost one-half the inductor current ripple w.r.t. two level implementation. The double line frequency power decoupling is addressed by a dynamic dc-link approach, which allows a large swing of the dc-link to reduce the decoupling capacitor requirement, enabling an all-film capacitor implementation. This topology also significantly reduces the high-frequency capacitive coupled ground current by directly connecting the PV negative terminal to the grid neutral. Moreover, an adaptive dc-link voltage control scheme that optimally changes the average value of the dc-link voltage as the operating conditions (load and power factor) vary, has been proposed and thoroughly investigated from the perspective of better utilization of passive components and further reduction of switching losses. A SiC MOSFETs-based 1 kVA laboratory prototype has been built to validate the converter's operation at 200 V dc nominal input and 120 V/60 Hz ac nominal output with a wide range of power factor and load operations. Extensive experimental results validate the superior performance of the topology with the adaptive dc-link voltage control implementation showing a peak efficiency of 98.22% and a CEC efficiency of 98.03% at 50 kHz switching frequency.

Multilevel Single-Phase Converter With Two DC Links

In this article, a multilevel single-phase converter is proposed and investigated. Its structure is based on cascaded-transformer systems, which are very interesting in applications in which a single dc source is available. The features of well-known multilevel cascaded H-bridge and transformer-based solutions are integrated into the proposed converter. As a result, the number of synthesized voltage levels can be optimized without excessively increasing the number of transformers. The basic configuration has six two-level insulated-gate bipolar transistor legs, two injection transformers, and two dc links (the lowest voltage dc link may be a floating capacitor or be connected to a small dc power source). The configuration is generalized and the calculation of the transformer's turns ratios as well as the dc-link voltages to maximize the number of voltage levels is provided. The proposed configuration is compared with cascaded H-bridge and a single-phase shared leg converter, which are also cascaded by means of transformers. Compared with the conventional converters, the proposed one has lower switching losses and higher conduction losses. Thus, the proposed configuration is more interesting in terms of semiconductor losses for high-voltage and low-current applications. Experimental and simulation results are shown to demonstrate the feasibility of the system.

Energy Saving and Economic Analysis of Switched Reluctance Motor in Agricultural Applications

Improvement of efficiency in electrical machines for water lifting applications in agricultural sector results in large energy savings, which is very much important in the present scenario of energy crisis. Single and three phase induction motors are most commonly used in such applications. However, these machines consume more energy due to their low efficiencies. A comprehensive performance evaluation including the machine design, selection of converter topologies, method of control, practical implementation of drive system, and vibration analysis for an agriculture applications is not done so far. This paper discuses to design Switched Reluctance Motor suitable for use in agricultural applications. Select suitable drive systems for this motor, giving considerations to lower switching losses and easiness of control. To investigate suitable control strategies for the speed control of the motor. Experimental validation of the performances of the motor, along with the vibration analysis. A real time experiment is also conducted to demonstrate the suitability of Switched Reluctance Motor drive for water lifting application and finally, per year unit consumption of Single Phase Induction Motor and Switched Reluctance Motor are compared to prove the economic superiority of Switched Reluctance Motor.

Fixed-frequency phase-shift modulated PV-MPPT for LLC resonant converters

The micro-inverter has attracted a great deal of attention in PV systems since it offers a superior solution for the shading problem in wide spreading of AC module technology, where each PV module has its own power conditioner. The micro-inverter is implemented from two-stages: DC–DC conversion and DC–AC conversion. This paper focuses on the first-stage of the micro-inverter including its high-gain and maximum power point tracking (MPPT). To achieve these features, an efficient MPPT algorithm is proposed for the LLC resonant-converter. Resonant converters are very promising topologies, due to their inherent features such as high-efficiency and very high-switching-frequency operation. Consequently, they have a small footprint and low switching losses due to zero-voltage-switching (ZVS) operation. To include resonant converters in PV applications, MPPT control is applied. Due to the non-symmetrical operation nature of resonant converters and pulse width modulated converters, the traditional MPPT techniques found in the literature are not suitable for direct application to the resonant converters. They need to be well-tuned before application to a resonant converter. To ease the usage of resonant converters in PV applications, this paper develops a novel phase-shift fixed-frequency MPPT algorithm that is compatible with the LLC resonant converter. It also reduces the EMI when compared to variable-frequency modulation due to the use of ZVS and a fixed frequency. The proposed MPPT technique achieves good performance, high steady-state efficiency and good dynamic response. The complete design procedure and analysis for the proposed MPPT phase-shift algorithm are presented in this paper. Finally, the presented system is validated based on PSIM simulations and hardware implementation on a 300-W prototype.

A New PFC Design With Interleaved MHz-Frequency GaN Auxiliary Active Filter Phase and Low-Frequency Base Power Si Phase

Wide bandgap (WBG) power semiconductors offer lower switching loss and higher power density than silicon but suffer from significantly higher cost. In this article, we introduce a design methodology which uses a low-frequency silicon base power processor to achieve high efficiency and low cost, and a high-frequency WBG fractional power active filter to reduce harmonics and achieve high power quality. The mixed use of WBG and Si delivers the same WBG benefits but at a reduced component cost. A boost PFC converter based on this design principle is reported that comprises two interleaved Si and GaN phases. We develop a new unified control strategy to allow the base power processed efficiently by the Si phase switching at a low frequency of 10 kHz and the harmonics to be minimized by the MHz-frequency GaN phase as an active filter. A 2.1-kW Si/GaN interleaved PFC prototype exhibits a peak efficiency of 98.04% and a power factor of 0.998, even with a frontend diode bridge. The new interleaved PFC is validated by simulation and experimentally to achieve excellent efficiency, power density, and harmonics mitigation at a cost much lower than a full-scale WBG design.

Design and Development of Driver Protection Circuit of Self Turn off Devices Applies to Electric Vehicle Fast-Change Mode

In this paper, based on the design of the chip UAA4002 one for electric vehicle fast charge mode of self-turn-off device driver protection circuitry to power transistor, for example, study design optocoupler isolation circuit, control circuit, anti-saturation circuit, composite buffer circuit, Further integration of the formation of self-turn-off device drivers, isolation, protection circuit, which has a simple circuit structure, function, high reliability, low switching losses, fast response.