An Efficient and Reliable Bridgeless PFC Decoupling Converter

Purpose. To obtain analytical dependencies for the precise calculation of the stator current of a frequency-regulated three-phase short-circuited induction motor and to estimate the components of its main electrical power losses, which are spent on the transportation magnetic power losses (to the magnetization circuit) and additional power losses (through the motor air gap), as well as with using the obtained refined dependencies to research the electromagnetic processes and energy modes of the frequency-regulated induction motor when its speed and load change. Methodology. The method of generalized vectors is used for the refined calculation of the electromagnetic processes and energy modes of the frequency-regulated induction motor. Results. Based on the catalog data and parameters of the induction motor’s equivalent replacement circuit, also the specified values of its useful rotational torque and speed, refined analytical dependencies were obtained for the calculation of the main electromagnetic power losses of the frequency-regulated induction motor, which take into account the influence of all types of power losses, which present in it, as well as – power losses spent on transporting magnetic losses (to the magnetization circuit) and additional losses (through the air gap of the motor). With the help of the obtained dependencies, the energy modes (including main power consumption and electromagnetic power losses, efficiency factor, power factor) of the frequency-regulated induction motor in the driving and generator modes of its operation in relation to the first (at speeds not higher than the nominal) and the second (at speeds above the nominal) speed control zones for the operating ranges of the motor useful rotational torque and speed changes were calculated. Originality. A refined analytical calculation dependence has been obtained for determining the active projection of the generalized stator current vector of a frequency-regulated induction motor, which takes into account the presence of additional power losses and the component of electrical losses caused by the transportation of additional power losses through the air gap of the motor; an analytical dependence is also proposed for determining the increment of the mentioned active projection, which is due to the transportation of magnetic power losses to the motor magnetization circuit. Practical value. Analytical calculation dependencies are proposed for the quantitative assessment of errors (as a percentage of mentioned values) in steady-state modes for determining the main electromagnetic power losses of the frequency-regulated induction motor, caused by the absence (in comparison with relevant studies from known publications) of taking into account additional and magnetic power losses, as well as – the influence of electrical component losses caused by the transportation of the mentioned power losses through the air gap or to the magnetization circuit of the motor, respectively. References 16, tables 5, figures 2.

For low-power applications, this paper presents the development and design of a compact and ultra-highly efficient half-bridge LLC resonant converter. By using Galium Nitride (GaN) devices and high-efficient magnetics, the efficiency and power density of resonant converters can be improved. Compared to Silicon MOSFETs, GaN high-electron-mobility transistors (GaN HEMT) have a lower output capacitance and gate charge, resulting in lower driving loss and shorter dead times. Consequently, the proposed LLC converter based on GaN devices has excellent performance characteristics such as ultra-high efficiency, low switching losses, compact size, high voltage endurance, high operating temperature and high operating frequency. Furthermore, the proposed resonant converter features soft switching properties that ensure that the switches and diodes on the primary side are always switched at zero voltage and current. By doing so, LLC resonant converter switching losses are significantly reduced by up to 3.1%, and an overall efficiency of 98.5% is achieved. The LLC resonant converter design with GaN HEMT has great advantages over Si MOSFET solution regarding efficiency, overall losses, switching loose and power factor correction. A 240 W, 240 V to 60 V half-bridge GaN HEMT LLC resonant converter is simulated with a switching frequency of 75 KHz, along with the comparative analysis of the Si metal oxide semiconductor field effect transistor (MOSFET) solution. Moreover, the design and analysis of highly efficient magnetics with a power factor of 0.99 at full load is presented. A 240-Watt single stage LED driver with power factor correction is also designed to verify and compare the performance of proposed LLC resonant converter.

Purpose Votage source converter (VSC) based or current source converter (CSC) based shunt active power filter (SAPF)? It is the main question in harmonic elimination project using SAPF.This paper presents some criteria based on which the designer can decide which type of filter is more suitable for implementation of the project according to the nature and characteristics of the project. Design/methodology/approach Owing to the importance of cost and power losses criteria, relevant equations will be formulated and comparative analysis will be carried out between conventional structures based on CSC or VSC. For validation of analyses, simulation results have been studied in the MATLAB–SIMULINK environment. Findings Simulation results have examined two important criteria of power losses and costs. Although the results show the superiority of VSSAPF to CSSAPF in both criteria, this comparison is performed in a general and conventional condition. Using third-order filters of inductive-capacitive-inductive (LCL) type in VSSAPF, using insulated-gate bipolar transistor (IGBT) with reverse-voltage blocking ability in CSSAPF, which eliminates the need to use series diodes, and the use of superconducting technology in the DC-side endpoint in CSSAPF, not only reduce the difference of cost and losses in two schemes but also may lead to the lower costs and losses in CSSAPF than VSSAPF. Originality/value This paper is the result of many years working on active power filter and can be useful for engineers who are engaged in industrial projects.

The analysis of processes in two types of power factor correctors is carried out: in the topology of the classic boost power factor corrector and in the topology of the bipolar power factor corrector. The theoretical overview of the processes in the considered power circuits was made. The analytical models are developed for calculating power losses in two types of power factor correctors. Simulation spice models of two topologies of circuits with models of power diodes and transistors are presented. The convergence of the power loss calculation results according to the developed analytical model and the power loss calculation results in a simulation model of converters is shown. A comparison of power losses in each power semiconductor component of the circuits is made. The efficiency of using a bipolar power factor corrector is shown when operating from a network with a wide voltage range.

This work presents a low cost PFC (Power Factor Correction) based BLDCM (Brushless DC Motor) drive targeting low power household appliances. Development of a highly efficient BLDCM drive with minimum amount of sensing requirement is the primary objective of this work. The switching losses in the VSI (Voltage Source Inverter) feeding BLDCM is reduced by electronically commutating the BLDCM and controlling its speed by controlling the voltage of the DC bus. A PFC buck-boost converter is used as a front-end converter due to its simplicity in design, minimum number of component count and its ability to buck and boost the voltage to control the speed over a wide range. The PFC buck-boost converter operating in DICM (Discontinuous Inductor Current Mode) is used for the control of DC bus voltage. An inherent PFC is achieved for variation of speed over a wide range at universal AC mains (90–265 V). The obtained PQ (Power Quality) indices are within the recommended limits of international PQ standards IEC 61000–3-2. The performance of proposed BLDCM drive is simulated in MATLAB/Simulink environment and validated experimentally on a developed prototype of the drive.

The power ratings of wind energy conversion systems (WECS) are increasing considerably due to high demand on wind power. Thus, multilevel power converters are becoming an interesting solution in the largest WECS, especially the three-level neutral-point-clamped (3L-NPC) thanks to its simple implementation and proper performance compared to other topologies. However, the main drawback of the 3L-NPC is that the power losses are unevenly distributed among the switching devices, limiting its output power capability. Current literature focuses on the three-level active neutral-point-clamped (3L-ANPC) as an evolution of the 3L-NPC, enabling a more even power loss distribution. However, in the 3L-ANPC there are still some devices suffering from both large switching and conduction power losses. Thus, this paper proposes new design guidelines for a 3L-ANPC inverter to force that each device mainly withstands either switching or conduction power losses. Then, the most suitable device is selected for each position, enabling a significant improvement in power loss distribution, thermal performance, converter efficiency and output power capability. A 2 MW low-voltage WECS is simulated with an electro-thermal model developed in PLECS, reaching a reduction of around 25% in power losses, a reduction of 50% in maximum junction temperature increase above ambient temperature, a reduction of 75% in maximum junction temperature variation, and an increase of around 85% in converter output power rating, compared to the conventional 3L-NPC and the 3L-ANPC.

This paper proposes a method to control the output voltage of an online UPS system based on active power decoupling. The experimental results confirm that the proposed method reduces the DC voltage ripple by 72%. Moreover, this paper proposes a technique to control the output voltage during power failure.

This paper compares the efficiencies of insulated gate bipolar transistor-based voltage and current source inverters. Test circuits that replicate the functionality of a single switching pole of each converter topology are used to measure the switching trajectories and loss characteristics of the semiconductor devices. These results are then used to simulate the losses for complete 3-phase voltage and current source inverters. Switching losses are shown to be dominant in the voltage source inverter whilst conduction loss is dominant in the current source inverter. It is shown that neither power converter operates more efficiently than the other over the complete operating range, with an equivalently rated voltage source inverter being preferable at lower power levels and the current source inverter being more efficient at higher power levels. (6 pages)

In this paper, an improved Zero-Voltage-Transition (ZVT) two-cell interleaved boost Power Factor Correction (PFC) converter is proposed and investigated. A new auxiliary circuit is designed and added to two-cell interleaved boost converter to reduce the switching losses. Only one auxiliary switch is used in the active soft switching auxiliary circuit. The main advantage of this auxiliary circuit is that it not only provides ZVT in the boost switches but also provides soft switching in the auxiliary switch and passive diodes. Therefore, the switching losses of the converter can be reduced. Compared to the previous published soft switching interleaved boost converters, only one auxiliary switch is needed in the auxiliary unit, so the auxiliary unit and control circuit are simple. A 1kW, 50 kHz two-cell interleaved boost PFC converter with an improved ZVT auxiliary circuit has been simulated using average current control method and the results are presented. Simulation results show that the main switches, the auxiliary switch and passive diodes are operating under soft switching mode.

The inherent dead angles of the input line current in buck power factor correction (PFC) converter deteriorates the power factor (PF). This article introduces a new bridgeless single-phase buck (PFC) converter with reduced components. This converter is designed to operate in discontinuous conduction mode (DCM) to achieve inherent PFC with a simple structure. The DCM operation gives additional advantages, such as low turn- <sc xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">on</small> losses and reduced complexity of the control circuitry. Unlike the buck PFCs, in which dead angle is the main drawback, in the proposed converter the PF is improved and the dead angle is eliminated by applying an auxiliary switch. Besides, the efficiency is further improved by employing the bridgeless structure. The switching losses are eliminated due to achieved zero current switching (ZCS) at the turn- <sc xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">on</small> and turn- <sc xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">off</small> of the main switches, and also ZCS at the turn- <sc xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">on</small> and zero voltage switching at turn- <sc xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">off</small> of the auxiliary switch. The proposed topology is successfully implemented on a 120 W prototype converter at 110 Vrms input voltage and 48 V output voltages, and its performance is experimentally verified. The results show the total harmonic distortion of 5.3% and efficiency of 93.1% at the rated load.

Tomlinson-Harashima precoding (THP) can be combined with geometric mean decomposition (GMD) to decouple a multiple- input multiple-output (MIMO) channel into multiple single-input single-output (SISO) subchannels with identical signal-to-noise ratios (SNRs). The combined system is called GMD-THP MIMO system. In this system, there is an increase in the transmission power caused by the interferences cancellation at the transmitter. To bind the transmission power, a modulo operation is used at the transmitter. However, there is still an overall increase in transmission power and this loss is referred to as power loss. A corresponding modulo operation at the receiver to demap the signals will create modulo errors. Performance loss due to the modulo errors is referred to as modulo loss. In this paper, we do a tradeoff between the power loss and the modulo loss to obtain the minimum combined loss. This tradeoff is achieved by adjusting the modulo size of the modulo operation. Detailed theoretical analysis of the power loss and modulo loss are done and from the analysis, the optimum modulo size for the tradeoff is found. Simulations are carried out to confirm the theoretical analysis and to prove that tradeoff improves the BER performance of the GMD-THP MIMO systems.

In this paper, a coupled-inductor Sepic-type power factor corrector (PFC) with soft-switching is proposed to drive high brightness LED panel. The two inductors in the Sepic-type PFC are magnetically coupled to lower volume. A soft-switching cell composed of an active switch, a resonant inductor and a resonant capacitor is embedded into the PFC to obtain zero-voltage switching (ZVS) feature so as to promote converter efficiency. The proposed PFC is suitable for universal-line input 85Vac ~ 265 Vac for low output voltage applications. Over the input voltage range, it can achieve high efficiency and high power factor. To drive LED panel, a digitalized feedback control loop is adopted to accomplish current sharing, voltage regulating, and dimming feature. A prototype is designed, analyzed and implemented to demonstrate the feasibility of the Sepic-type PFC. Simulation results and hardware measurements have illustrated that the proposed PFC driving LED panel can achieve high power factor, improve efficiency, and accomplish current sharing and dimming feature.

This paper is focused on active power consumption and losses in industrial and commercial facilities, depending upon supply voltage quality parameters. The shunt capacitors for power factor correction affect directly supply voltage level and harmonic distortions of supply voltage and current and hence affect power losses in industrial facilities, particularly in induction motors. In the paper practical measurement methods are described for estimating power losses when power factor correction capacitors are used. The impact of capacitors upon supply voltage level and harmonic distortions is discussed. Measurement results of voltage and current harmonics spectrum in industrial 0,4 kV power systems are shown.

The Landsman converter based on a power factor correction (PFC) in bridgeless (BL) configuration feeding a brushless dc motor (BLDCM) drive is proposed for low-power household appliances. The conduction losses associated with diodes are reduced by BL configuration and switching losses of solid-state switches of voltage source inverter are reduced by the use of low frequency switching signals in electronic commutation for the BLDCM. The front-end BL PFC based Landsman converter operating in the discontinuous inductor current mode is used for controlling the dc link voltage, and PFC is attained naturally with reduced conduction losses and switch stress. A single voltage sensor is used for controlling the dc bus voltage. A prototype is developed to study performance of the system for wide range speed control and power quality improvement. The experimental performance of BLDCM is presented for its functions at varying voltages of ac mains (90–265 V) to adhere to the limits defined by IEC61000-3-2 standard.

A single-stage power factor correction (PFC) circuit base on an isolated Asymmetric Dual Active Bridge (ADAB) converter is presented and analyzed in this paper. Power factor correction and isolated output voltage regulation are achieved using an optimized dual phase-shifting control strategy. The converter can work in step-up and step-down mode during half period of the AC input voltage. Soft-switching of all of the switching devices in both the primary and secondary-side circuits is implemented and thus switching loss can be reduced efficiently. In this paper, the operation principle and soft switching performance of this converter is analyzed in detail, and the results of the analysis are used to develop an optimized procedure for its design. Experimental results are given to verify the effectiveness and advantages of the presented single-stage AC-DC converter.