Output Filter Components Research Articles

Multi-objective optimization of two-stage AC–DC power supply for reliability and efficiency using NSGA-II and meta-heuristic honey bee algorithms

This paper introduces a novel approach to simultaneously optimize the reliability and efficiency of a switching power supply (SPS) using the Non-dominated Sorting Genetic Algorithm (NSGA-II) and Honey Bee Algorithm (HBA). The proposed method uses a Markov model to evaluate the reliability of the converter and maximizes objective functions, including efficiency and reliability, using optimization algorithms to identify the optimum values of the converter parameters. The optimization algorithm determines the optimal values for converter parameters, such as switching frequency, transformer turn ratio, and DC-link voltage. It also fine-tunes circuit components, such as the power factor correction inductor, DC-link capacitor, and output filter components. A sensitivity analysis is carried out to assess the impact of various parameters on the multi-objective functions of the converter. The converter’s reliability and mean time to failure (MTTF) are evaluated using the Markov reliability model, considering all components’ short and open circuit faults. The failure rates of converter components are calculated using the MIL-HDBK-217 methodology. The results obtained from the NSGA-II and HBA are compared to identify the superior algorithm with the best-optimized parameters. Simulation results indicate that the proposed optimization technique enhances the converter’s reliability performance while maintaining its efficiency. Furthermore, this paper presents comprehensive analyses, comparisons, and experimental findings to demonstrate the converter’s fault-tolerant capability. The multi-objective optimization approach offers a practical and effective strategy for optimizing switching power supplies for efficiency and reliability

Accurate Design of Output Filter for DC–DC PWM Buck Converter and Derived Topologies

This paper presents an analysis of an LCR second-order low-pass filter capacitor to achieve a specified ripple output voltage in Buck, forward, Zeta, and Ćuk PWM DC-DC power converters for continuous-conduction mode (CCM). Current and voltage waveforms across output filter components are derived. Using the waveform of the ac component of the output voltage, an expression for the ripple voltage is developed in terms of the filter capacitance and equivalent series resistance. The results can be used for all PWM converters with the LCR output filter, such as Buck, forward, Zeta, and Ćuk PWM DC-DC converters. Theoretical results were in good agreement with simulation and experimental results.

Optimum Phase Count in a 5.4-W Multiphase Buck Converter Based on Output Filter Component Energies

This article presents an analysis of low-power, multiphase interleaved buck converters to illustrate the extent to which adding more phases is beneficial for reducing the passive components’ sizes. The analysis focuses on a typical converter application with a wide operating duty cycle range and requires good load transient. It is shown that by restricting the phase current ripple, the theoretical reduction in total inductor peak energy predicted for increased phase numbers is limited. The article assesses the benefit of inductor coupling and presents guidelines for coupling factor selection to avoid steady-state inductance roll-off over the wide input voltage range. Standard printed circuit board (PCB) manufacturing design rules are shown to place a practical phase count limit considering the reduction in total inductor size. PCB integrated, air-core solenoid and spiral inductors are implemented in both single- and two-phase 5.4 W, 20 MHz buck converter prototypes. When compared with single-phase designs, two-phase spiral inductors are 44% smaller, and the two-phase solenoid has a 54% lower loss. The two-phase prototype converter achieves better overall efficiency and peaks at almost 90% at <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">V_IN</i> = 4.5 V, <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">V_OUT</i> = 1.8 V, and <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">F_SW</i> = 20 MHz.

A High Efficiency Modified Forward Converter for Solar Photovoltaic Applications

In this paper, a modification of a conventional forward converter and a new mixed-stranded transformer winding technique are proposed for the development of a simple and high efficiency isolated dc-dc boost converter for solar photovoltaic applications. The conventional single switch forward converter topology is modified for simplification and elimination of losses due to the output filter components. A new mixed-stranded transformer winding technique is proposed to minimize the leakage inductance between the primary and tertiary windings for reducing losses. A pulse frequency modulation technique (PFM) is employed for reducing switching losses at low power operation. An experimental prototype of 300 W with a voltage step-up ratio of 1:12 has been built to obtain dc output voltage between 360-480 V for the dc input voltage of 30-40 V. Through the experimental results, it is shown that the converter can boost the input voltage according to the step-up ratio and exhibits a remarkably high dc-dc power conversion efficiency with a flat response curve. The average efficiency of around 95.5 % and peak efficiency of 97.6% are obtained.

A New Active Output Filter (AOF) for Variable Speed Constant Frequency (VSCF) Power System in Aerospace Applications

In this paper a new “active output filter” (AOF) for variable speed constant frequency (VSCF) power system in aerospace applications is proposed. The proposed AOF is envisioned as a power semiconductor filter block. In the proposed system the passive L-C output filter components are replaced by an H-bridge. The H-bridge is operated at high frequency to inject voltage harmonics to achieve a sinusoidal output voltage to the load. Advanced wide band gap devices can be employed in the design of AOF block to obtain high performance with simultaneous reduction in size. The proposed AOF concept offers a significant reduction in size/weight compared to passive L-C. Further, in the presence of AOF the main VSCF inverter can be operated in a six-step and/or at a reduced PWM frequency. An example 250 kVA, 3-phase 400-Hz system with the proposed AOF concept is evaluated via simulation with a corresponding passive L-C filter configuration. Experimental results on reduced kVA laboratory prototype are discussed.

A Multiphase Class-D Automotive Audio Amplifier With Integrated Low-Latency ADCs for Digitized Feedback After the Output Filter

A $5 \times 80$ W class-D audio power amplifier for automotive applications is presented. The amplifier is implemented in a 140-nm bipolar CMOS DMOS SOI. Configurable digital-loop filters can compensate for a range of LC output filters and their high loop gain (>50 dB between 20 Hz and 20 kHz) suppresses non-idealities of the output filter and enables low-cost output filter components. Key elements are the integrated low-latency $\Delta \Sigma$ analog to digital converters (ADCs) which digitize the output signals directly at the speaker load, after the output filter. The ADCs use filtering finite impulse response digital to analog converters in their feedback path to create an input–output transfer with a negative group delay at low frequencies. The ADCs have 116-dBA DR and −108 dB total harmonic distortion (THD). The bridge-tied load amplifier supports multiphase pulse-width modulation for lower electromagnetic interference. It operates with supplies from 6 to 25 V and with loads down to $1\Omega$ and achieves 19- $\mu \text{V}$ idle noise (Awtd) and 0.004% THD + N.

Development of 50-kV 100-kW Three-Phase Resonant Converter for 95-GHz Gyrotron

This paper describes the development of a 50-kV 100-kW cathode power supply (CPS) for the operation of a 30-kW 95-GHz gyrotron. For stable operation of the gyrotron, the requirements of CPS include low output voltage ripple and low arc energy less than 1% and 10 J, respectively. Depending on required specifications, a three-phase series-parallel resonant converter (SPRC) is proposed for designing CPS. In addition to high-efficiency performance of SPRC, three-phase operation provides the reduction of the output voltage ripple through a minimized output filter component that is closely related to the arc energy. For allowing symmetrical resonant current from three-phase resonant inverter, the high-voltage transformers are configured as star connection with floated neutral node. This facilitates balanced voltage on each secondary winding. In addition, distinctive design of the high-voltage rectifier is introduced, taking into consideration the effective series stacking of diodes by means of the parallel resonant capacitor. In particular, the implementation of the high-voltage part including transformer and rectifier is presented in detail. For providing high power density and high reliability, effective methods for winding the high-voltage transformer and stacking rectifier diodes are discussed. Finally, the developed CPS achieves 95.5% of maximum efficiency, 0.92 of maximum power factor, 500 W/liter of power density, 0.6% of output voltage ripple, with 8.3-J arc energy.

OUTPUT FILTER SIZING OF GRID CONNECTED BUCK-BOOST INVERTER USING GRAPHICAL APPROACH

Wide range input voltage converters are merely required in photovoltaic and wind energy conversion systems which have dynamic output voltage due to irradiance and wind speed fluctuations. This paper presents a comprehensive analysis and design approach of grid connected buck-boost inverter for wide input voltage application. Sizing of a LC output filter component is emphasized in this paper. It is important to size the filter properly to obtain a trade-off between output current ripple and reactive power supplied into grid when inverter is in stand-by mode. A graphical method is employed to determine filter parameters. The presented method is found to be straight forward and easy from practical point of view.

An Optimal Method to Design a Trap-CL Filter for a PV AC-Module based on Flyback Inverter

The power factor and total harmonic distortion (THD) are important considerations when designing an output filter. In the case of the photovoltaic (PV) ac-module, the size and weight also have to be taken into consideration. This paper proposes an output filter to reduce size and weight, and provides the optimal design method for a PV ac-module. The proposed output filter consists mainly of a conventional CL filter with a trap filter. The trap filter is used to eliminate the harmonic at the switching frequency that contains most of the harmonics. Therefore, total inductance and the size of the filter can be reduced although the output filter components are increased. This paper presents analysis of the proposed filter characteristics in detail. Also, an optimal design method reducing the size of the output filter components including the damping resistor is proposed. The proposed methods are verified on the experimental prototype rated at 320 W with an ac-module based on the interleaved flyback inverter. The total filter inductance and volume are, respectively, reduced to 9.54% and 26.62% with the same performance.

Effects of Spread Spectrum on Output Filter of Buck Converter

Consideration is being given to the use of spread spectrum technology (SST) as the one for noise suppression and the one with coexisting action on the components of output filter of buck converter. The analysis shows that the use of SST produces an additional stress on the output filter components such as power inductor and output capacitor. For both components switching modulation generates extra power loss (as opposed to unmodulated case) which increases with the growth of frequency deviation. During this more energy is dissipated just within frequencies which are below nominal switching frequency, than is saved within frequencies that are higher than the nominal switching frequency. But this effect is not strong; it is possible to compensate it by slight increase of nominal switching frequency and thus to maintain high efficiency of converter in the case of SST usage as well. DOI: http://dx.doi.org/10.5755/j01.eee.19.5.4367

Development Overview of Solid-State Multimegawatt Regulated High-Voltage Power Supplies Utilized by NBI and RF Heating Systems

Regulated high-voltage power supplies (RHVPSs) are important power sources in high-power heating and current drive systems for a tokamak. Along with high power at output, these power supplies meet the requirements of fast dynamics (on the order of few microseconds), low ripple factor, and good output regulation. A development overview is presented for RHVPS ranging from 14 to 80 kV at several-megawatt power with typical output results. Having extensive tests performed with an 80-kV 75-A RHVPS, it is being regularly used for a neutral beam injector (NBI) at the Institute for Plasma Research (IPR). A large number of identical and series-connected switched power modules (SPMs) are fed from multisecondary transformers. Pulse step modulation control applied to an insulated-gate bipolar transistor switch within SPMs regulates output. Different rise and fall times of voltage can be set from few microsecond to millisecond range. Fast detection of instantaneous overcurrent reduces turnoff time within 2 μs. Due to higher frequency of ripple at higher voltages, output filter component value is of smaller order, which, in turn, limits fault energy below 10 J. The development of RHVPS at IPR started by making a functional prototype at lower rating (14 kV; 35 A) to have an experience in testing design concepts. This was divided in various activities like selection of topology, selection and design of different subparts, e.g., control, switching power converters with protections, and multisecondary transformers. Having successful results and testing all functional parameters on prototype, a series of RHVPSs at higher ratings (up to 80 kV), are developed and installed for NBI and radio-frequency heating system. The design details for each subsystem along with results are discussed.

Transformerless series sag compensation with a cascaded multilevel inverter

The use of a cascaded multilevel inverter for transformerless sag/dip compensation is investigated. This topology is investigated as a cost-effective means for series sag compensation by eliminating the large injection transformer and output filter components that are used in conventional series injection devices. This prototype inverter is designed for sag compensation of a 250-kVA load. In this design, cost effectiveness plays a major role in the selection of the energy storage and the switching components. Control schemes are discussed for series sag compensation with this multilevel inverter. New control methods for sag compensation and injection are also introduced. A prototype is developed and the control schemes of this sag compensator are successfully verified in the practical results and show successful compensation for sags for different types of loads. The performance of this compensator makes it promising for future power rating upgrade and industrialization.

Evaluation of actively clamped resonant link inverter for low-output harmonic distortion high-power-density power converters

The suitability of a soft-switched actively clamped resonant DC-link (ACRDCL) inverter for low-output harmonic distortion/high-power-density power conversion is evaluated. Modulation and control techniques for achieving low-output harmonic distortion are described. Performance and power density of the ACRDCL inverter are maximized through the optimal design of the clamp circuit, resonant components, and output filter components. The ACRDCL inverter simulation and design are validated experimentally. For the same output kilovoltamperes, efficiency and harmonic performance as the ACRDCL inverter, hard-switched designs are compared. Methods to increase the power density of the ACRDCL are proposed, including the use of recently developed nonpunchthrough insulated gate bipolar transistors.

A new space-vector-based control method for UPS systems powering nonlinear and unbalanced loads

In this paper, a new real-time space-vector-based control strategy is presented for three-phase uninterruptible power supply systems powering nonlinear and unbalanced loads. The proposed control strategy generates the inverter reference and gating signals in closed loop and guarantees high-quality output voltages at the load terminals. The approach, which is implemented on a digital signal processor, adapts to a wide variation of nonlinear and unbalanced load conditions without specific knowledge of the output filter (L-C) component values. Analysis and experimental results on a 10-kVA prototype are presented. The results show that the output voltage is restored at heavy nonlinear and unbalanced load.

Analysis and design of a three-phase current source solid-state VAR compensator

A reactive power compensation (RPC) system which uses a three-phase current-source force-commutated PWM (pulsewidth-modulated) rectifier is presented and analyzed. Pulsewidth modulation is also investigated as a means of reducing the size of reactive components. The proposed RPC system can compensate for leading and lagging displacement power factor. Other areas of investigation include the selection of rectifier input and output filter components and the closing of the loop around the reactive power command signal. finally, predicted results are verified experimentally. >

A novel power MOSFET switching-mode power supply

Increasingly, the operating frequency of switched-mode power supplies (SMPS) eliminates the need for bulky magnetic and output filter components, thereby reducing their overall weight and volume. Power MOSFETs, which are capable of operating at much higher frequencies than those achievable with present-day bipolar transistors, have by now established their credibility in switching-mode power supply applications. In the paper, a fundamentally different scheme of switched-mode power supply, in which the transformer demagnetizing winding (clamping winding) is eliminated by using a simple RC clamping circuit, is discussed. It is shown that this scheme is capable of delivering a steady DC output voltage, under a much wider variation of DC source voltage.

Improving the power conversion process in UPS systems

Typical specifications for uninterruptible power supply systems require constant regulated output AC voltage under variable or temporarily defaulted AC utility bus conditions. Such an operating environment results in a variable DC link operation with serious derating of the UPS inverter, the output transformer and the output filter components. Two link voltage control methods that overcome this problem are discussed in this paper. With the first method, a boost chopper is activated to maintain the DC link voltage constant when the battery voltage dips below its rated value. In this mode, the chopper operates only during small time intervals, thus not contributing to system losses. With the second method, the battery voltage is stepped-up under feed-back control through a boost chopper. This allows the use of fixed inverter switching patterns with further improvement in the utilization of system components. Specifically, it is found that power handling capacity is improved by 65% without compromise in the system complexity and/or system performance.