Power Loss Model Research Articles

Hierarchical power allocation algorithm for D2D‐based cellular networks with heterogeneous statistical quality‐of‐service constraints

Device-to-device (D2D) communication can increase network coverage, spectrum efficiency and energy efficiency (EE) within the existing cellular infrastructure, which makes it a promising architecture for the future networks. Due to the diversification of services, heterogeneous statistics quality-of-service constraints are considered in this study, where cellular users are concerned about the delay constraint and D2D user groups pay more attention to the outage probability of data transmission. The power allocation problem of cellular users can be solved by optimising the capacity-payoff power-loss game model. Upon exploiting Lagrange dual decomposition and the Newton iteration method, the power optimisation problem of cellular users is transformed into a parameter optimisation problem. Due to the limited energy resource of D2D users, EE is the focus of D2D user groups. Using fractional programming and convex optimisation techniques, energy-efficient optimal power allocation algorithms of D2D users are proposed subject to the outage probability constraint. As a result, a power allocation algorithm based on hierarchical game is conceived for efficiently solving the power optimisation problem. The simulation results show that the proposed algorithm can obtain a performance improvement compared with other algorithm and converge within a certain number of iterations.

Analysis and Optimization of Variable-Frequency Soft-Switching Peak Current Mode Control Techniques for Microinverters

This paper presents a detailed power loss model for a microinverter with three different zero voltage switching boundary conduction mode (BCM) current modulation methods. The model is used to calculate the optimum peak current boundaries for each modulation method. Based on the power loss model, a dual-zone modulation method is proposed to further improve the microinverter efficiency. The proposed modulation method provides two main benefits: the addition of one more soft switching transition and low inductor peak current. The additional soft switching transition reduces switching losses by means of zero current switching. The lower peak current boundary reduces inductor rms current and conduction losses as well as allowing the output filter inductor to be smaller and more efficient. An improved BCM peak current control method was proposed and implemented on a microinverter prototype. The control circuit provides a highly accurate representation of the filter inductor current waveform and also provides galvanic isolation that simplifies control circuit design. The experimental results on a 400-W three-phase half-bridge microinverter validate the theoretical analysis of the power loss distribution and demonstrate that further improvement in efficiency can be achieved by using the proposed dual-zone modulation method.

Comparison of SiC Voltage Source Inverters Using Synchronous Rectification and Freewheeling Diode

For power converters with inductive loads, a freewheeling path is needed for the current due to reactive power. The MOSFET synchronous rectification (SR) is widely used to reduce the conduction loss during the freewheeling period. Due to the wide band gap of silicon carbide (SiC), the intrinsic body diode of SiC MOSFET exhibits a high voltage drop. Hence, an antiparallel SiC Schottky diode is normally implemented to eliminate its conduction. However, the external SiC Schottky diode is not fully utilized as it only works during the dead time. In this paper, the hard-switching SR is investigated in an SiC three-phase inverter and compared with a conventional inverter using freewheeling diode (FWD). An improved power loss model for the two inverters has been developed. It is found that the inverter using SR has higher efficiency due to the smaller switching loss. A 7-kW prototype of SiC three-phase inverter is built, which achieves a peak efficiency of 98.8% ( $\pm$ 0.15%) and 98.5% ( $\pm$ 0.15%) at 40 kHz using SR and FWD, respectively. This paper confirms that the SiC MOSFET is an ideal candidate for the SR.

Research on Power Loss of Continuously Variable Transmission Based on Driving Cycles

In order to further enhance the fuel economy of vehicles with continuously variable transmission (CVT), a CVT power loss model under dynamic condition is established based on the power loss model of each transmission component and the vehicle dynamic model. With driving cycles 10-15, NEDC and US06 as input, the distribution of CVT power loss and the influence of the main losses to vehicle fuel economy are analysed. The results show that the variation loss, oil pump loss and torque converter loss are the main losses of CVT power loss under driving cycles, and the metal belt and oil pump have relatively larger fuel saving potential. At low speed reducing the pump loss is more effective to fuel saving, while at high speed reducing the variation loss is more effective.

Comprehensive Power Losses Model for Electronic Power Transformer

The electronic power transformer (EPT) has higher power losses than the conventional transformer. However, the EPT can correct the power factor, compensate the unbalanced current, and reduce the line power losses in the distribution network. Therefore, the higher power losses of the EPT and the consequent reduced power losses in the distribution network require a comprehensive consideration when comparing the power losses of the EPT and conventional transformer. In this paper, a comprehensive power losses analysis model for the EPT in distribution networks is proposed. By analyzing the EPT self-losses and considering the impact of the nonunity power factor and the three-phase unbalanced current, the overall power losses in the distribution network when using the EPT to replace the conventional transformer is analyzed, and the conditions in which the application of the EPT can cause less power losses are obtained. Based on this, the sensitivity analysis for the EPT comprehensive power losses model is carried out by comparing the value of each parameter variation impact on the EPT losses model. In the case study, the validity of the comprehensive power losses model is verified.

Thermomecanical study of high speed rolling element bearing: A simplified approach

Rolling element bearing is an essential component in mechanical transmission because it reduces friction between two rotating parts. Two main approaches to evaluate power losses are proposed in literature: (i) global engineering models using few input data; (ii) local models which are more accurate but need much more information on rolling element bearing geometry. Based on thermal network approach, an intermediate model is developed in this study. This new model allows obtaining lumped information (temperature of rings) with a minimum of input data (external geometry only) and by using global power loss models. This intermediate model is developed for angular contact ball bearing under oil jet lubrication for high speed application. Thermal network results are compared with experimental findings.

Finite element method model to predict bulk and flash temperatures on polymer gears

Abstract A FEM thermal model was implemented to predict the bulk and flash temperature of gears in general and polymer gears in particular. Using the capabilities of a gear power loss model previously validated, a solution for the temperature rise and distribution along the tooth is suggested. The accuracy of the power loss model is decisive for the prediction of gear temperature field by FEM model. The FEM model was validated with experimental results from the literature. The model allows to predict the bulk temperatures for oil jet, dip lubrication or non-lubricated conditions. The FEM model allows an higher accuracy on the calculation of the load carrying capacity of polymer gears, whose mechanical properties are critically dependent on the bulk temperature.

Modeling of power losses in poly-V belt transmissions: Hysteresis phenomena (enhanced analysis)

To predict the power losses in poly-V belt transmissions, theoretical models have been developed taking into consideration different types of power loss in a Front Engine Accessory Drive (FEAD). Even though power losses in a FEAD come from different phenomena (belt or tensioners hysteresis, belt-pulleys slip, etc.), the analysis in this paper focuses on the elastomeric belt hysteresis losses due to dynamic bending, stretching, shear, flank and radial compression of the belt rubber. DMA (Dynamical Mechanical Analysis) experiments are performed in order to determine the intrinsic loss modulus of the belt elastomeric constituent causing the loss of energy. This study leads to the determination of a hysteresis power loss map of a belt transmission.

Optimized Design of GaN Switched-Capacitor-Converter-Based Envelope Tracker for Satellite Application

Envelope tracking and envelope elimination and restoration (EER) are two important techniques used to improve efficiency of power amplifiers. They employ a power supply called envelope tracker to provide a dynamic voltage that tracks the envelope of the transmitted signal. This paper presents an implementation of the envelope tracker based on a multilevel converter in series with a linear regulator for satellite application. In order to have highly efficient and light solution, a switched-capacitor-converter-based multilevel converter is proposed. For the multilevel converter, duty cycle, switching frequency, capacitors, and inductors are optimized based upon the precise power loss model. Two prototypes (GaN-based and Si-based) are fabricated, aiming for a 5-MHz radio frequency envelope signal tracking with a maximum output power of 40 W. The experimental results verify the effectiveness of the proposed configuration with 96.2% efficiency of the multilevel converter and 75% of the envelope tracker. Besides, comparison experiments are performed between the Si-based and GaN-based transistors, which show that the GaN transistors offer better efficiency and, therefore, are preferred for satellite application.

Power loss and temperature rise model for an IGBT in a variable polarity welding power supply with a reverse voltage stabilizer

Power loss and temperature rise model for an IGBT in a variable polarity welding power supply with a reverse voltage stabilizer

Scaling-Based Analysis and Modelling of Power Losses in Amorphous and Nanocrystalline Alloys

Scaling-Based Analysis and Modelling of Power Losses in Amorphous and Nanocrystalline Alloys

A Fast Electro-Thermal Model of Traction Inverters for Electrified Vehicles

In this paper, a fast electro-thermal model of traction inverters for electrified vehicles is proposed. First, a thermal model considering the thermal coupling is presented and experimentally verified. The impact of the thermal spreading effect, heat convection, and temperature-dependent material thermal properties on the accuracy of the linear assumption is investigated by ANSYS-Fluent simulation. In order to reduce the influence of the temperature-dependent thermal conductivity on the accuracy of the thermal model, the average temperature is applied to determine the thermal conductivity of the power module package. Second, an accurate temperature-dependent switching power loss model is represented as the lookup table through experimental measurements. In order to simplify the lookup table, the switching power loss is considered proportional to the dc-link voltage and, therefore, the inputs of the lookup table are current and temperature. Finally, a scheme to speed up the online junction temperature estimation is proposed by considering both the thermal network properties and the required accuracy. With the proposed calculation rate determination method, the total computational time for the junction temperature estimation is reduced significantly.

Physics-Based Analytical Model for Input, Output, and Reverse Capacitance of a GaN HEMT With the Field-Plate Structure

This paper presents an analytical model for input, output, and reverse capacitance of a normally on AlGaN/GaN high-electron mobility transistor (HEMT) with a gate field-plate structure, when the device is in the subthreshold regime. Together with the existing model for the output I–V characteristics, the proposed capacitance model provides the complete set of analytical equations that relate the physical design parameters to the electrical characteristics of the device. The model was verified by the experimental characterization of a HEMT. In comparison to the physics-based models implemented in Finite Element Analysis tools, the obtained capacitance model has substantially lower level of complexity and, therefore, it is more suitable for implementation into iterative design optimization algorithms. In order to verify the proposed model for such usage, the prototype of a high-frequency buck converter was built, using previously modeled GaN HEMT as the main switch. The hybrid analytical-behavioral power loss model of a high-frequency buck converter was implemented into Simplorer simulation tool, using the proposed physics-based model as the device description for the capacitive part. The efficiency measurements showed good agreement with the simulation results, even at 20 MHz of switching frequency in the low range of the output power.

Minimize Reactive Power Losses of Dual Active Bridge Converters using Unified Dual Phase Shift Control

This paper proposed an unified dual-phase-shift (UDPS) control for dual active bridge (DAB) converters in order to improve efficiency for a wide output power range. Different operating modes of UDPS are characterized with respect to the reactive current distribution. The proposed UDPS has the same output power capability with conventional phase-shift (CPS) method. Furthermore, its implementation is simple since only the change of the leading phase-shift direction is required for different operating power range. The proposed UDPS control can minimize both the inductor rms current and the circulating reactive current for various voltage conversion ratios and load conditions. The optimal phase-shift pairs for two bridges of DAB converter are derived with respect to the comprehensive reactive power loss model, including the reactive components delivered from the load and back to the source. Simulation and experimental results are illustrated and explained with details. The effectiveness of the proposed method is verified in terms of reactive power losses minimization and efficiency improvement.

A power loss model for Archimedes screw generators

This paper presents a complete power loss model for an Archimedes screw used for power generation (ASG) including a non-dimensional model to predict power losses due to outlet submersion flooding. This model amends a prior idealized, frictionless ASG performance model to include power losses due to bearing friction, outlet exit effects, internal hydraulic friction and outlet submersion. This study presents data and a derived relationship for power losses due to outlet submergence and found that unmodified Manning’s coefficients can be used to model internal fluid friction losses. Laboratory experiments on a scale-model ASG were conducted to determine variable relationships and validate power loss models. The performance of a 7 kW grid-connected ASG was measured and used to validate model predictions. The proposed ASG power loss model improves the prior frictionless power model significantly and was generally capable of predicting the power output of a real-world ASG.

Dynamic Electrothermal Model of Paralleled IGBT Modules With Unbalanced Stray Parameters

Compared with single-module applications, unbalanced stray parameters come about frequently in the process of installing paralleled IGBT modules, which could result in some distinctions of current sharing and temperature distributions. To focusing on depicting this practical issue, a novel dynamic electrothermal model extended to paralleled systems is proposed in this paper to establish a comprehensive transient model to characterize the relations of power losses, junction temperature, and unbalanced parasitic elements. The model can describe the interactions of current distributions and thermal dissipations between paralleled modules. In addition, the variation of unbalanced temperature during transient process can be obtained with the proposed electrothermal model. First, the stray inductance parameters in the paralleled branches are analyzed in detail by finite-element-method simulation tool. And based on impedance analysis, an improved power loss model is built up, considering the interaction of paralleled devices. Moreover, by the method of resistor-capacitor networks extracted from numerical simulations of 3-D structural model, the transient thermal impedance of devices and cooling system is obtained for fast and accurate electrothermal cosimulation of the paralleled system. Experimental results are carried out to verify the proposed model and coincide with the theoretical analysis.

Modeling of power losses in poly-V belt transmissions: hysteresis phenomena (standard analysis)

A simulation software is being developed for predicting the power losses in poly-V belt transmissions. For this purpose, some theoretical models have been implemented considering different types of power losses taking place in a Front Engine Accessory Drive (FEAD). Even though these power losses come from different phenomena, the analysis in this paper is focused on the elastomeric belt hysteresis losses due to dynamic bending, stretching, shear, flank and radial compression of the belt rubber. Experimental tests are performed in order to determine the intrinsic loss modulus of the belt elastomeric constituent causing the loss of energy. This study permits determining a hysteresis power loss map of a belt transmission.

Modelling of steady-state mechanical power losses in planetary gear trains of automatic transmissions

Modelling of steady-state mechanical power losses in planetary gear trains of automatic transmissions

Temperature-related power loss modeling for buck converter

Temperature-related power loss modeling for buck converter

Modeling of Power Losses Caused by Hidden Tree-Related High Impedance Faults

The great majority of overhead distribution systems in urban and rural areas of countries such as Australia, Iran and etc., are in interfering with vegetation. This phenomena leads to high impedance faults (HIFs) which not produce enough fault current to be detectable and consequently causes electrical energy losses. In this paper, according to experimental data obtained from measurements, the effective factors in power losses caused by trees are studied and a new numerical model of power loss is presented so as to reflect the effects of environmental conditions and biological classification. The base of this method is according to Samuelson theory. In proposed algorithm, the impacts of species, short-term environmental conditions (temperature and humidity) and long-term environmental conditions (Seasonal variations in physiology) on the power loss estimation are fully considered. Experimental investigations on a real low voltage (380 V) and medium voltage (20 kV) distribution network verify the algorithm’s operation.