Switching Losses Research Articles

Reduced stage three phase multisource hybrid converter for integration of PV and grid power

A three-phase-based Modified Dual Source Inverter has been proposed in this manuscript. The existing three-phase system is plagued with multistage power conversion, reducing its efficiency. The proposed converter can integrate two sources (AC and DC) simultaneously and supplies power to the three-phase load. It can switch its operation from the grid to grid-solar, solar to grid, as per the availability of the source. The inverter can operate as a three-phase DC to AC inverter, AC to AC inverter, and it can use grid and PV power directly with the help of a sino-squo-sino waveform. The system has been studied when switching from one mode to another. The system behavior has been analyzed on MATLAB SIMULINK and experimental setup. The proposed approach has been experimentally validated and operated using a TEXAS-based microcontroller (TMS320F28739d). The proposed method has reduced the THD to 4.32% when operated on solar and grid. The THD is 0.25% when operated on the grid power. The proposed system has also been compared based on components. It uses six IGBTs, One Mosfet and three Bidirectional switches.The reduced number of components reduces switching losses, which increases the system's efficacy and performance.

Simple Design Scheme for a 300 kW Modular NPC Inverter Using Thermal RC Network Analysis

This paper proposes a simple design scheme for a modular NPC inverter using thermal RC network analysis. The proposed design process is an efficient and straightforward approach to designing the heatsink for a 300 kW modular neutral-point-clamped inverter. The heatsink design plays a crucial role in achieving high power density of a power converter because the weight and size of the heatsink are primarily influenced by its type. The structure and dimensions of the heatsink are mainly determined based on the generated heat by losses of the power semiconductor switches. In this paper, a thermal RC network model was established using parameters from the power switch module and was applied to the simulation of the power converter. The thermal losses of the power semiconductor switches were calculated via this process, and the heatsink was designed according to the calculated thermal losses. The proposed design scheme was analyzed and compared with the thermal fluid dynamic model. To validate the feasibility of the proposed design process, The simulation results were compared with experimental results.

Novel Electric Propulsion System Analysis Method for Electric Vertical Takeoff and Landing Aircraft Conceptual Design

This paper proposes novel enhancements to the electric propulsion system analysis method for electric vertical takeoff and landing (eVTOL) aircraft conceptual design by considering the electrical characteristics of each electrical device in a more accurate manner. To this end, three modules for motor, inverter, and battery analysis are constructed using equivalent circuits and semi-empirical models. First, the motor analysis module is developed using equivalent circuit analysis with the operation control strategy for a permanent-magnet synchronous motor. Second, the inverter analysis module is built using average loss models for the switching and conduction losses. Third, the battery analysis module is improved using the near-linear discharge model to consider the voltage drop during operation. Moreover, additional modules, such as those for calculating the battery stack in series and parallel, as well as regression models for the motor and inverter performance parameters and consideration of the drive system type (direct or indirect, including a reduction gear), are implemented. A comparative study is presented from an analysis and design perspective while changing the drive system type (direct or indirect) and gear ratio, which highlights the importance of modeling electrical characteristics during eVTOL aircraft conceptual design.

A New Design and Embedded Implementation of a Low‐Cost Maximum Power Point Tracking Charge Controller for Stand‐Alone Photovoltaic Systems

This article presents a low‐cost maximum power point tracking (MPPT) charge controller designed to efficiently charge solar batteries using a simple and robust MPPT method, while providing protection against over‐currents and over‐voltages. The proposed MPPT approach utilizes a modified Incremental Conductance (INC) algorithm adapted to low‐cost embedded controllers, as it avoids all the mathematical division calculations typically used in the conventional INC algorithm. It also introduces a modified step size based only on photovoltaic (PV) power change to enhance tracking accuracy and convergence speed. Furthermore, to reduce the stress and switching losses of DC–DC converter, a feedback control with two proportional and integral (PI) compensators is also used to control both the PV voltage and to protect the battery from over‐currents using PV power limitation technique. Simulation results, carried out under MATLAB/Simulink, demonstrate the good performance of the proposed control scheme regarding any variations in atmospheric conditions, both for the MPPT control and for the battery charge control. Finally, a processor‐in‐the‐loop (PIL) test using a low‐cost Arduino MKR ZERO board is also performed to verify the hardware implementation of the proposed method. PIL results are in totally accordance with MATLAB/Simulink simulation results, which further proves the effectiveness of the proposed method.

Efficiency and PF Improving Techniques with a Digital Control for Totem-Pole Bridgeless CRM Boost PFC Converters

A totem-pole bridgeless boost converter is one of the most promising topologies for the power factor correction (PFC) stage in high-power applications due to its high efficiency and small number of components. However, due to the totem-pole structure of the field-effect transistor (FET), very high switching loss occurs via the reverse recovery current of the body diode. To solve these problems, critical mode (CRM) control is a good solution to achieve the valley switching technique. With valley switching of CRM control, the switching loss decreases drastically with decreasing turn-on voltage. But, although the CRM control enables valley switching, it is hard to make an exact valley switching control with general zero-voltage detection circuits. In addition, when a frequency limitation scheme is applied to prevent a very high frequency, the switch can operate with hard switching at the boundary of the frequency limitation. Furthermore, the CRM boost PFC has a low PF and high total harmonic distortion (THD) under light-load conditions due to the large negative current resulting from resonance between the inductor and parasitic capacitance. It becomes worse at near-zero input voltage since the resonance current becomes larger near zero-input voltage. Therefore, in this paper, a totem-pole bridgeless boost PFC converter with high efficiency, high PF, and low THD is developed using TMS320F28377 by Texas Instruments. Based on the basic digital structure of the totem-pole bridgeless converter, the proposed controls help with exact valley switching, PF and THD improvement, and frequency limitation. The prototype converter is verified using 90–264 VAC input voltages and 450 V/3.3 kW output specifications.

Voltage Equalization of Series Energy Storage Unit Based on LC Resonant Circuit

In energy storage systems, multiple energy storage monomers are usually connected in series to obtain higher voltages, but the inconsistency of the voltage of each energy storage monomer will reduce the utilization of the storage unit. To address this problem, this article proposes a method for equalizing the voltage of series energy storage units based on LC resonant circuit. The equalization circuit consists of a switch array and an LC resonant converter, which can achieve energy transfer between any monomer and continuous multi‐monomer, and realize zero‐current conduction of the switch. The equalization circuit does not have a large number of magnetic components, and for each additional energy storage monomer, the circuit only needs to add a pair of switches, which has the advantages of high flexibility and expandability. Finally, the equalization simulation experiments are conducted on the Matlab/Simulink platform for the energy storage unit composed of four series‐connected energy storage monomers. The experimental results show that under static equalization, the voltage reaches equalization in about 25 min and the equalization efficiency reaches 96.64%, which greatly reduces the switching loss, improves the equalization speed and efficiency, and verifies the feasibility and effectiveness of the method.

Hybrid MGWO- CSO optimized high gain Relift Luo converter for PV based grid tied PMBLDC drive system

Permanent Magnet Brushless Direct Current (PMBLDC) motor has become one of the most important motors in high performance drive systems, for industrial uses especially for electric vehicle (EV) applications to minimize their torque and current ripples. This work proposes a PV based high gain DC-DC converter for uninterruptible constant power supply to the PMBLDC drive application. PMBLDC drive with Hall Effect sensorsis used to make the variable speed operation due to its controllability. In this work, a Relift Luo converter is utilized because of its negligible ripple in output DC voltage, high voltage gain and reduced switching losses. To regulate this converter, PI controller is implemented and to tune the parameters of the controller, Hybrid Crow Search -Modified Grey Wolf Optimization (MGWO-CSO) techniqueis implemented. The surplus energy from PV is transferred to grid through Single phase Voltage Source Inverter (1 φVSI) after generatingadequate power to PMBLDC motor. When there is no power in Photovoltaic (PV)cell during night time, stored energy in grid gives supply to the PMBLDC motor. The motor is effectively controlled by the PI controller along with the hysteresis controller. Furthermore, the developed work is executed in MATLAB/Simulink to foreshow its effectiveness. As a consequence, the proposed work accomplished low THD value of 1.34, high efficiency of 98.2% with reduced switching lossescompared to the conventional techniques.

Modelling and simulation of sinusoidal pulse width modulation controller for solar photovoltaic inverter to minimize the switching losses and improving the system efficiency

Modelling and simulation of sinusoidal pulse width modulation controller for solar photovoltaic inverter to minimize the switching losses and improving the system efficiency

Compatible Selective Harmonic Elimination for Three-Phase Four-Wire NPC Inverter with DC-Link Capacitor Voltage Balancing

In this paper a Compatible Selective Harmonic Elimination (CSHE)-PWM is designed for three-leg four-wire (3L/4W) Neutral Point Clamped (NPC) inverter. The proposed CSHE-PWM is capable of eliminating both triplen and non-triplen harmonics from phase voltages and empowers 3L/4W NPC to handle both single/three-phase and linear/nonlinear loads. It has been mathematically proved that DC capacitors self-voltage balancing is achieved thanks to direct control of phase voltage waveform symmetry. Moreover, the cancellation of specified triplen and non-triplen orders has the advantage of having low capacitors voltage ripple. Therefore, the applied technique not only helps removing one leg of the inverter that reduces associate complex calculations and switching losses, but also directly controls phase voltage harmonic profile compared to SHE-PWM for four-leg four-wire (4L/4W) NPC. CSHE-PWM is practically tested on a NPC inverter prototype to validate the efficient harmonic elimination from the phase voltage waveforms along with capacitors voltages balancing under symmetrical/asymmetrical loads.

A Hybrid Modulation Technique for Operating Medium-Voltage High-Power CHB Converters Under Grid Voltage Disturbances

Power converters, and particularly multilevel converters, are key elements in the current energy scenario. Among them, Cascaded H-Bridge Converters (CHB) are a popular and versatile solution for many industrial applications. Technical literature provides multiple modulation techniques for its operation. Among them, hybrid-PWM modulation techniques provide a good trade-off between switching loss and output voltage quality. In this work a hybrid modulation technique is presented which allows not only the fundamental block switching operation of some power cells but also a harmonic control over a specific harmonic distortion present in the grid. To validate the operation of the proposal, several experimental results have been reported to demonstrated the good behaviour of the proposed modulation technique.

Thermal Control of Quasi-2-Level Super-Switch by Power Routing

The requirement of power converters for Medium Voltage (MV) and High Voltage (HV) applications accelerates faster than the development of semiconductor switches capable of handling such voltage levels. For that reason, it is common to use the series connection of semiconductors with auxiliary snubbers. In contrast, an increased number of semiconductors is more likely to cause reliability problems due to increased redundancy, unequal thermal conditions, or different remaining lifetime. On the other hand, the quasi-2-level super-switch (Q2L SS) yields increased flexibility, enabling precise readjustments of the voltage and switching losses of individual devices of the converter due to the utilization of small capacitors. The power routing capability of the Q2L SS to redistribute the switching losses from the overheated semiconductors is presented in this paper. The influence of power routing on performance of Q2L SS is investigated with the Double Fourier analysis and experimental results.

Tunable continuous domain bound states based on Fabry-Perot cavities and their applications

Excellent optical absorbers are always characterized by high quality factors and perfect absorption; however, these absorbers usually encounter the ohmic losses due to traditional surface plasmon resonance, which limits their absorption performance in practical applications. To address the problem, a tunable bound state in the continuum (BIC) based on Fabry-Perot cavity is proposed in this work. Figure (a) shows the structural model of the designed Fabry-Perot cavity absorber, which consists of Ag as a substrate, a layer of the dielectric material Al<sub>2</sub>O<sub>3</sub> above the Ag substrate, and a high-refractive-index grating as the top dielectric layer Si ridge. By adjusting the thickness parameter <i>d</i> of Al<sub>2</sub>O<sub>3</sub>, the transformation of BIC into q-BIC is achieved. Specifically, when <i>d</i> is increased from 273 nm to 298 nm, the BIC can be transformed into quasi-BIC, and the perfect absorption of the absorber in the continuum spectrum can be increased to 100%. In this work, the factors affecting the perfect absorption are explored by using the interference theory; theoretical calculations of the quasi-BIC are carried out by using the coupled mode theory and impedance matching theory; the physical mechanism of the BIC is explained by using the electric and magnetic field theory. The BIC is caused by the electric and magnetic dipole modes as well as the mirror image of the base Ag, which causes the interferential phase cancellation effect. Compared with the conventional absorber, the proposed absorber has excellent structural parameter robustness and a wide range of BIC modulation. More importantly, the absorber has excellent sensing performance with a maximum sensitivity of up to 34 nm/RIU and a maximum quality factor of 9.5. Last but not least, the absorber also achieves dual-frequency open-light performance, the maximum modulation depth and the minimum insertion loss of the dual-frequency switch reach 99.4% and 0.0004 dB, respectively. These findings have significant implications in the fields of photonics, optical communication, and sensor technology.

Simultaneous Current Ripple and Switching Loss Reduction for Three-Level T-Type Inverter Under Switch Fault Conditions

Simultaneous Current Ripple and Switching Loss Reduction for Three-Level T-Type Inverter Under Switch Fault Conditions

High fidelity modeling of pumped storage units for optimal operation of a multi-energy co-generation system

Pumped storage, as the storage technology with the largest installed capacity and mature technology, plays a key regulation role in the multi-energy co-generation system. The core of regulation accuracy is the high-fidelity modeling of pumped storage. This paper improves the insufficiency of the conventional pumped storage model (CPSM) in exaggerating the flexibility of pumped storage units by setting up non-operable operating condition regions, and incorporates the condition switching loss into the model consideration, on the basis of which a high fidelity pumped storage model (HFPSM) is established. Secondly, a multi-objective function of the operation model is set from the consideration of economy, environmental protection and stability, and a engineering application level optimal operation model of wind power-photovoltaic-thermal power-pumped storage multi-energy co-generation system based on HFPSM is proposed. Thirdly, two research indicators, the thermal power volatility indicator and the pumped storage unit utilization rate, are proposed. Fourthly, combined with examples, the effects of CPSM and HFPSM on the optimized operation of the system are investigated. It is found that adding four 50MW pumped storage units to the system can reduce the total operating cost by 10.34% and the environmental cost by 83.61%. The optimization of the high fidelity model is better under the premise of ensuring safe, stable and efficient operation of the system. Optimizing the number of unit startups and shutdowns for the high fidelity model to 25.8% of the conventional model. Finally, by exploring the optimal operation of a multi-energy co-generation system with different pumped storage installed capacities, it is found that the proposed high fidelity model makes the optimization results more in line with the actual operation. The flexibility of the pumped storage units no longer increases with the increase of installed capacity, which provides a reference for the planning of the storage capacity in the multi-energy co-generation system.

Dynamic Analytical Switching Loss Model of SiC MOSFET Considering Threshold Voltage Instability

Dynamic Analytical Switching Loss Model of SiC MOSFET Considering Threshold Voltage Instability

Minimisation of AC Grid Side Input Power Factor Angle for Three-phase AC to Three-phase AC Matrix Converter under Varying Load

Abstract Minimisation of AC grid side input power factor angle for a ‘matrix converter (MC)’ improves the efficiency of the grid. Input volt-ampere requirement is minimum if the current drawn by the ‘MC’ is sinusoidal and input displacement power factor (IDPF) is unity. A MC is inherently capable of maintaining a unity displacement power factor (UDPF) angle at its input terminals. However, the input currents drawn from the grid are not sinusoidal. The high-frequency ripples are suppressed by input current filters (ICFs).These filters additionally introduce a leading phase angle for the current which varies with the loading. This phase lead can be compensated by adjusting the angle between the input current space vector and the input voltage space vector of the MC. The computation of this adjustment angle depends on the estimation of power losses in the switching devices. A simple method is proposed in this paper to estimate the switching losses without measuring device voltages and currents using the perturbation technique. The perturbation logic depends on input current, instantaneous active and reactive power computed at regular intervals of time. The proposed method effectively minimises the IDPF angle very close to zero. The experimental results are included for validation,

Single Phase Sine-Wave Inverter with High DC Bus Utilization Using Natural Compensation

Abstract- In this paper, a new fixed frequency single phase sine-wave inverter topology - having high DC bus utilization - is presented. The main inverter uses six IGBT switches operating at low frequency in over-modulation mode to create a five-level voltage waveform; thus, having low switching losses with high DC bus utilization. A series active power filter (SAPF) using power MOSFETs helps to remove the major harmonic voltages. No isolated DC power supply is required across the SAPF that works on a simple feed-forward compensation (instead of feedback), based on the principle of natural compensation. The DC bus voltage needed for the SAPF is about half of the inverter, thus the SAPF has low switching loss even at the designated switching frequency. The switching frequency components of the SAPF remain in the output as they are not compensated, necessitating the use of a small filter at the output to attenuate them, to create a low total harmonic distortion output voltage with higher fundamental compared to the conventional schemes using Sinusoidal Pulse Width Modulation. The proposed inverter is suitable for fixed frequency backup power supply or other applications like renewable energy connection to the power grid.

A Zero-Voltage-Transition H5-Type Transformerless Photovoltaic Grid-Connected Inverter

Efficiency and leakage current are two major issues for transformerless grid-connected inverters (TLI). Soft-switching technologies can reduce switching losses and be applied in TLIs. Herein, a zero-voltage-transition H5 type (ZVT-H5) inverter with soft turn-on and turn-off transitions of high-frequency main switches is derived from basic resonant tanks. Compared with the hard-switching H5 (HS-H5) inverter, the conversion efficiency of ZVT-H5 is significantly improved. Moreover, the reverse recovery problem of freewheeling diodes is alleviated under the operation of the auxiliary resonant network. Meanwhile, a diode clamping branch is employed to achieve constant common-mode characteristic for the ZVT-H5. The construction process of the proposed topology is described, and the operation principle of the auxiliary resonant network is analyzed. Moreover, the resonant parameter design of ZVT-H5 and its circuit performance are discussed in detail. Finally, the experimental results of a 3-kW prototype at 100 kHz switching frequency are provided to verify the effectiveness of the ZVT-H5.

A High-Efficiency Integrated Converter for LED Driver

Enhancing the efficiency in the light-emitting-diode (LED) drivers is a noteworthy issue as it not only helps saving energy but also causes the long life span of the drivers. In this paper, a new LED driver with improved efficiency is proposed. Efficiency improvement is achieved without using any active or passive component to perform soft switching conditions. In the proposed driver, buck and buck-boost converters are integrated. The freewheeling diodes and inductors - of the two converters - are replaced by one diode and one inductor. So, the proposed driver constitutes a single-stage driver with a simple structure that uses only one controlled switch, one freewheeling diode, and one inductor. Besides its simple structure, the driver works with a constant frequency, which leads to using a simple controller. Efficiency improvement is obtained by changing the inductor size and LEDs arrangement rather than using the active clamp or snubber circuits. To decrease the switching losses in the proposed driver, the average of the input current is kept constant while the peak of the pulsating input current - which passes from the switch and freewheeling diode - is decreased. Moreover, power losses of the semiconductor components in the proposed driver are investigated, and consequently decreased, leading to improvement in the system's overall efficiency. Finally, a 10 W experimental driver is built and tested. The experimental results are consistent with theoretical analysis.

Novel SV-PWM Strategies for Six-Phase Induction Motor Drive With Reduced Switching Losses and Common-Mode Voltage

Novel SV-PWM Strategies for Six-Phase Induction Motor Drive With Reduced Switching Losses and Common-Mode Voltage