Inverter Losses Research Articles

Dynamic Loss Minimization of Finite Control Set-Model Predictive Torque Control for Electric Drive System

This paper proposes a dynamic optimization strategy of finite control set-model predictive torque control for permanent magnet synchronous machines, which takes into account the inverter losses and machine losses simultaneously. In order to reduce the switching losses (or to optimize the switching sequence) of the inverter, a recognized and feasible constrain which considers the accumulated ON/OFF times of the switches is implemented. The machine losses are taken into account by utilizing an optimal stator flux reference. An alternative loss model control method is proposed to calculate the optimal stator flux reference, which combines the conventional maximum torque/ampere method and the conventional loss model control method. Furthermore, a discrete-time machine model is introduced, which can reduce the predictive error at relative low switching frequency. The key results are illustrated by a combination of simulation and prototype interior permanent magnet machine drive measurements.

Analysis and Design of Solar Photo voltaic Grid Connected Inverter

This paper presents common mode voltage analysis of single phase grid connected photovoltaic inverter. Many researchers proposed different grid tie inverters for applications like domestic powering, street lighting, water pumping, cooling and heating applications, however traditional grid tie PV inverter uses either a line frequency or a high frequency transformer between the inverter and grid but losses will increase in the network leading to reduced efficiency of the system. In order to increase the efficiency, with reduced size and cost of the system, the effective solution is to remove the isolation transformer. But common mode (CM) ground leakage current due to parasitic capacitance between the PV panels and the ground making the system unreliable. The common mode current reduces the efficiency of power conversion stage, affects the quality of grid current, deteriorate the electric magnetic compatibility and give rise to the safety threats. In order to eliminate the common mode leakage current in Transformerless PV systm two control algorithms of multi-carrier pwm are implemented and compared for performance analysis.The shoot-through issue that is encountered by traditional voltage source inverter is analyzed for enhanced system reliability. These control algorithms are compared for common mode voltage and THD comparisons. The proposed system is designed using MATLAB/SIMULINK software for analysis.

The reduction of dynamic losses in sine wave inverters by controlling modulation multiplicity of the output voltage

Improving the energy efficiency of inverters possible to achieve by reducing dynamic losses, due to the reduction of modulation multiplicity relative to the current values of the total harmonic distortion coefficient. From obtained relations possible in analytical form express modulation multiplicity for specific values of the inverter parameters and total harmonic distortion coefficient.References 4, figures 1, table 2.

Effects of Battery Pack Voltage Level on Traction Inverter Efficiency in Parallel Hybrid Electric Vehicles

In this paper a precise and simple methodology will be introduced for modeling and calculating the Voltage Source Inverter (VSI) losses in Hybrid Electric Vehicles (HEV) application. The noteworthy traction inverter losses, consisting switching and conduction losses of diodes and IGBTs, are important for evaluating the overall efficiency and obtaining the optimized value of its dc-link voltage as well. For this purpose, the effects of different battery voltage levels on the inverter losses are examined.

Applicability improvement and hysteresis current control method simplification in shunt active filters

Hysteresis current control method is widely used in Pulse Width Modulation (PWM) inverters because of simplicity in performance, fast control response and good ability in limiting peak current. However, switching frequency in hysteresis current control method with fixed bandwidth has large variation during a cycle and therefore causes nonoptimal current ripple generation in output current. One of basic problems in implementing hysteresis current control is its variable switching frequency that causes sound noise and increase in inverter losses and also high frequency current components injection to the source current. In this paper, a fixed frequency hysteresis current controller is proposed for grid connected inverters. In the proposed approach, the required bandwidth of the controller is calculated according to system parameters. Also, the derivative of the reference current is eliminated to solve the problems associated with practical implementation of the converter. Finally, a shunt active filter has been used for removing the current harmonic components generated by non-linear loads. Proposed method is simple to perform and reliable, and also has been simulated in MATLAB software environment.

Reduced sensor configuration of a power factor correction based single‐ended primary inductance converter fed brushless DC motor drive

This study presents a power factor correction-based single-ended primary inductance converter (PFC-SEPIC) feeding brushless DC (BLDC) motor drive for low-power household appliances. In a conventional scheme of BLDC motor, the speed is varied by controlling the duty ratio of high-frequency pulse width modulation signals, which increase the switching losses in the voltage source inverter (VSI) feeding BLDC motor. However, this study presents a BLDC motor of which the speed is controlled by adjusting the DC bus voltage of the VSI feeding BLDC motor. Moreover, a fundamental switching frequency of VSI is employed for reduction of its switching losses by operating the BLDC motor in electronic commutation. A PFC-based SEPIC is designed for its operation in discontinuous inductor current mode such that the voltage control is achieved using a single voltage sensor with inherent PFC at AC mains; which also makes it a cost effective solution for low power applications. The proposed drive is implemented on the developed converter for the performance evaluation. This drive shows high efficiency as compared with conventional schemes of BLDC motor drive with satisfactory power quality performance at various speeds satisfying IEC 61000-3-2 standard.

Model for estimating the energy yield of a high concentrator photovoltaic system

The prediction of the energy yield of HCPV (high concentrator photovoltaic) systems is crucial to evaluate the potential and promote the market expansion of HCPV technology. Currently, there is a lack of experience in the modelling of these kinds of systems due to the special features of such technology. In this work, a practical model based on simple mathematical expressions and atmospheric parameters is introduced. The proposed model takes into account the main important parameters which influence the output of a HCPV system such as cell temperature, spectrum and efficiency of the inverter and other losses of the BOS (balance of system). The results obtained are validated using the data of a HCPV installation located at the University of Jaen in southern Spain and monitored daily every minute since 2011. The model accurately predicts the monthly energy yield with a deviation ranging from 4.07% to −0.47% and the annual final energy yield with a deviation of 0.9%.

Four Novel PWM Shoot-Through Control Methods for Impedance Source DC-DC Converters

This study proposes four novel pulse width modulation (PWM) shoot-through control methods for impedance source (IS) galvanically isolated DC-DC converters. These methods are derived from a PWM control method with shifted shoot-through introduced by the authors in 2012. In contrast to the baseline solution, where the shoot-through states are generated by the simultaneous conduction of all transistors in the inverter bridge, our new approach is based on the shoot-through generation by one inverter leg. The idea is to increase the number of soft-switched transients and, therefore, decrease the dynamic losses of the front-end inverter. All the proposed approaches are experimentally verified through an insulated-gate bipolar transistor-based IS DC-DC converter. Conclusions are drawn in accordance with the results of the switching loss analysis.

Predictive Control Method With Future Zero-Sequence Voltage to Reduce Switching Losses in Three-Phase Voltage Source Inverters

This paper proposes a predictive control method with zero-sequence voltage injection to efficiently reduce the switching losses of three-phase voltage source inverters (VSIs). In the proposed predictive control method, three-phase future voltage references modified by a zero-sequence voltage injection are generated to clamp one of the three legs with the largest load current. Furthermore, the future zero-sequence voltage, which is produced online with the future voltage and current references in every sampling period, optimally adjusts the clamping duration on each leg, depending on the load angle. In addition, the proposed method selects the zero vector on the basis of the polarity of the future zero-sequence voltage to reduce the switching losses. Using a predefined cost function, the proposed predictive control scheme chooses one optimal voltage state closest to the future voltage references modified by the zero-sequence voltage injection. Therefore, the proposed predictive control method can perform load current control and minimize the switching losses of the VSI under any load condition regardless of the load angle.

Reducing Switching Losses in BLDC Motor Drives by Reducing Body Diode Conduction of MOSFETs

This paper presents a new power electronic topology that aims to reduce switching losses in hard-switched inverters for brushless dc (BLDC) motor drives. This is achieved by extending the benefits of synchronous rectification used in low-voltage switch-mode dc-dc conversion to high-voltage motor drive applications and by minimizing the reverse conduction behavior of the intrinsic body diode of the synchronous rectifier MOSFET. The proposed topology for reducing body diode conduction includes the addition of a MOSFET in series with the rectifying switch and a SiC Schottky diode around the series switch combination. This paper focuses on theory, simulations, and experimental results and validates the benefits of proposed new topology for BLDC motor drive applications. An extension of this topology for sinusoidal back electromotive force permanent-magnet motors is also presented.

스위치 손실 감소를 위한 단상 3레벨 NPC 인버터의 새로운 스위칭 방법

This paper proposes a method of switching to improve power loss for the single-phase three-level NPC inverter. The conventional switching methods, which are called as the bipolar and unipolar switching methods, are used for single phase inverters using three-level topology. However, these switching method have disadvantage in the power loss. Because all of the switch are operated. To reduce the power loss of the three-level NPC inverter, clamp switching method is introduced in this paper. This way, one of the lag is fixed that switching loss is reduced. This paper analyzes and compares power losses of unipolar method and clamp method. The validity of the power loss analysis is verified through the simulation and experimental results.

Single Phase Series Resonant Inverter with Automatic Control

In this paper, a novel DC-AC single phase resonant inverter is proposed. When the switches are turned on and off, a conventional inverter generates switching loss because of hard switching. Thus inverter losses are increased .In this paper some protective measures have taken so that losses should be minimized and system become more efficient results in high efficiency of inverter.

Dual open-end stator winding induction machine fed by redundant voltage source inverters

In this paper, the authors propose the availability analysis of a dual open-end stator windings asynchronous machine. Each open-end stator winding is supplied by two PWM voltage source inverters. The active and passive redundancy of the inverters improves reliability, availability, and safety of the system since the loss of inverter losses does not stop the machine. Indeed, for active redundancy, in the case of failure of the inverter, the corresponding winding is disconnected and the other winding is supplied by the two healthy inverters. For passive redundancy, one winding is fed by two inverters and the two others are waiting; in the case of failure inverter, the roles will be reversed. Simulation results are carried out to show the ability of a fault-tolerant architecture.

Efficient Design of a High Speed PMSM Drive for Electric Vehicle Application Using Real Time Simulator

In this paper, a novel approach has been employed in order to investigate the efficient design of a vector control drive of a high speed permanent magnet synchronous motor (PMSM) for automotive application using analytical method and real time simulator. Most of vector control drives set the d-axis current to zero to decrease the magnitude of the source current and working with unit power factor. However, the optimal d-axis current is dependent to the motor specifications. An optimal estimation scheme has been proposed and tested in order to work with maximum efficiency based on the operation point. In the high speed application, because of high losses density and low capacity of heat dissipation, the importance of working in maximum efficiency point will be clear more and more. Also, measurement of inverter losses is very complicate in the analytical approach. In this paper, the precise model of the switches has been implemented using real time simulator. Real time simulator, is a complex electronic circuit which is composed of central processing units (CPUs), field-programmable gate array (FPGA), etc.-s known as an efficient tool obtains very exact model of the insulated-gate bipolar transistor (IGBTs) in order to have the precise losses model of the motor and drive. Both of the analytical approach and real time simulator prove the validity of the optimal estimation scheme.

Implementation of a Novel DC-AC Single Phase Resonant Inverter Using Soft Switching Boost Converter

In this paper, a novel DC-AC single phase inverter is proposed .when the switches are turned on and off, a conventional inverter generates switching loss because of the hard switching .thus the inverter losses increased. proposed system contains auxiliary circuit. the converter stage switches perform soft-switching because of the auxiliary circuit. Also inverter stage switches perform ZVS when the DC like voltage is zero. Therefore all the switching when the switches is turned on and off. Thus the proposed system reducing switching loss and voltage stress.

Multifrequency Inductive Power Transfer

This paper presents a generalized analysis of an inductive power transfer system where multiple frequencies are used to transfer power through the magnetic link. Specifically, we consider a system that amplifies both the fundamental and the third harmonic generated by a full-bridge inverter in order to transfer power to a receiver at both frequencies. The system is analyzed in a generalized manner, by looking at the transconductance function at the transmitter and the receiver for each of the harmonics. Using this approach, the emitted field strength, inverter losses, combined transmitter and receiver coil conduction losses, and VA ratings are compared to a reference single-frequency system. The analysis shows that the dual-frequency system can outperform the single-frequency equivalent for all metrics considered; however, in practice, a tradeoff between the performance criteria is necessary, since the optimal operation points for each criterion cannot be attained with a single design.

Optimizing Re-planning Operation for Smart House Applying Solar Radiation Forecasting

This paper proposes the re-planning operation method using Tabu Search for direct current (DC) smart house with photovoltaic (PV), solar collector (SC), battery and heat pump system. The proposed method is based on solar radiation forecasting using reported weather data, Fuzzy theory and Recurrent Neural Network. Additionally, the re-planning operation method is proposed with consideration of solar radiation forecast error, battery and inverter losses. In this paper, it is assumed that the installation location for DC smart house is Okinawa, which is located in Southwest Japan. The validity of proposed method is confirmed by comparing the simulation results.

Novel Pulse-width Modulation Strategy to Minimize the Switching Losses of Z-Source Inverters

This article proposes a novel pulse-width modulation strategy to minimize switching losses of the Z-source inverter. The Z-source inverter has different pulse-width modulation patterns unlike the conventional voltage source inverter. Shoot-through states have been inserted within the zero states of the traditional pulse-width modulation patterns of a voltage source inverter to boost DC input voltage. Thus, the Z-source inverter has six active states, two zero states, and additional shoot-through states differentiating the Z-source and conventional voltage source inverters. The currents flowing through the switches of the Z-source inverter are larger than those of the conventional voltage source inverter, because Z-network currents must flow through the switches during the shoot-through states. Therefore, shoot-through currents increase the total switching losses of the Z-source inverter. In this article, switching losses of the Z-source inverter with the existing pulse-width modulation strategy are analyzed in detail. Then, new modulation signals of the Z-source inverter are introduced to produce unique pulse-width modulation patterns that minimize the switching losses of the Z-source inverter. The switching losses of the Z-source inverter with both pulse-width modulation strategies are simulated and compared. In addition, an experimental system has been built and tested to verify the effectiveness of the proposed strategy.

Generic Losses Model for Traditional Inverters and Neutral Point Clamped Inverters

This paper presents a model of two very common inverters, a traditional inverter and neutral point clamped inverter, for calculating the losses in function of the parameters of the inverter datasheet. The model allows simulating the inverter branch under any conditions, not only nominal sinusoidal, and monitoring its losses at the same time, so the most significant parameters could be determined in losses terms. The optimization of the losses in inverters could create an important energy saving since it is present in most of the power applications, mainly renewable energies. Obviously, the model is based on the electrical equations of both semiconductors inverters so the mathematical development is exposed. Finally, the model is validated by solving the equations analytically together with the model simulation under nominal sinusoidal environment. DOI: http://dx.doi.org/10.5755/j01.eee.20.5.7106

Patterns of divergence of a large family of nodule cysteine‐rich peptides in accessions of Medicago truncatula

The nodule cysteine-rich (NCR) groups of defensin-like (DEFL) genes are one of the largest gene families expressed in the nodules of some legume plants. They have only been observed in the inverted repeat loss clade (IRLC) of legumes, which includes the model legume Medicago truncatula. NCRs are reported to play an important role in plant–microbe interactions. To understand their diversity we analyzed their expression and sequence polymorphisms among four accessions of M. truncatula. A significant expression and nucleotide variation was observed among the genes. We then used 26 accessions to estimate the selection pressures shaping evolution among the accessions by calculating the nucleotide diversity at non-synonymous and synonymous sites in the coding region. The mature peptides of the orthologous NCRs had signatures of both purifying and diversifying selection pressures, unlike the seed DEFLs, which predominantly exhibited purifying selection. The expression, sequence variation and apparent diversifying selection in NCRs within the Medicago species indicates rapid and recent evolution, and suggests that this family of genes is actively evolving to adapt to different environments and is acquiring new functions.