A novel dual-switch forward converter with input current ripple reduction

This letter is to present a Δ-Y hybrid impedance network based boost converter with reduced input current ripple. Comparing to the existing impedance network based boost converters to enhance the output port characteristic, i.e., voltage conversion ratio, of the traditional boost converter (TBC), the proposed converter applies the impedance network to improve its input port performance, i.e., the input current ripple issue. The proposed Δ-Y hybrid impedance network consists of the TBC's main inductor, an additional coupled inductor, and an additional resonant inductor and capacitor pair. Although the peak currents flowing through the diode and the switch are higher in comparison to the TBC, the proposed converter can remain TBC's voltage conversion feature and effectively reduce the input current ripple and the average current of the main inductor with the application of the Δ-Y hybrid impedance network. The operating principle of the proposed converter is explained and the principle of current ripple reduction is analyzed in detail. Experimental results from a prototype are carried out to validate the effectiveness of the proposed converter.

This paper considers input current-ripple reduction on Pulse-link DC-AC converter for fuel cells applications operated by zero-current-slope mode. For reducing the input current-ripple, series LC circuit has been connected in parallel at the Pulse-link DC-AC converter. The input current-ripple characteristics have two main domains with combination of series LC parameters. The current-ripple level depends on inductance values. Input current-ripple is reduced when the inductor current flown at series LC circuit has zero-slopes in one switching period. At that time, small parameters values can be achieved.

Multiphase dc-dc converters are widely used in power electronics. In the case of generating multiple output voltages from a common input voltage, converters have to operate at non-uniform duty cycles. This is challenging in regard to input current ripple minimization, as control techniques for interleaved operation of asymmetric converters are not well understood. In this paper, analytic formulas are derived to obtain uneven phase-shift angles for optimal ripple minimization. Simulations verify the performance of the proposed technique and compare it to conventional methods.

In renewable energy power conditioning system (PCS), like photovoltaic (PV) and fuel cell sources, the low input current ripple represents a very important issue to improve the source efficiency. This paper presents an analysis of the power losses and efficiency of two high boosting converters for PV and fuel cell applications, designed by the authors. The two converters are characterized by a single switching device and, the first topology, by a reduced input current ripple and, the second one, by a zero input ripple condition. In particular, the free ripple condition of the second topology is obtained by coupling the two inductors that are uncoupled in the first topology. A detailed mathematical analysis of the power losses and efficiency is presented together with an evaluation of the effects on the efficiency caused by coupling the inductors. The proposed concepts are demonstrated by simulation.

An improved soft switching dual-switch forward converter topology is proposed in this paper. Compared with conventional dual-switch forward converter, the proposed converter employs an auxiliary switch and a clamp capacitor to instead of two reset diodes. Therefore, its duty cycle can exceed 0.5 to achieve wide range input voltage, also soft switching can be achieved for all switches. Especially, voltage stress across main switches can be clamped at 1/2Vin, voltage stress across auxiliary switch can be clamped at Vin. In addition, due to clamp capacitor series with the transformer, duty ratio can be extended with equation Vo = {Vin(1-D)D}/N. Thus, as a kind of better cost-effective approach, it is very attractive for high input, wide range and high efficiency application.

Input current and its ripple of the interleaved boost converter with arbitrary number of phases are analyzed in details and the formula of quantifying input current and its ripple are derived. As a result, a new control approach of adjusting the active phase number and switching frequency to achieve the low or even zero input current ripples in the interleaved boost converter is proposed. Therefore the input filter can be significantly decreased on size and cost or even not needed in steady-state. In addition, the practical factors that affect the input current ripple are presented. Simulation and experimental results show that the input current ripple can be greatly decreased with this approach. Moreover, the principle of this control approach is also valid for other common interleaved dc-dc topologies.

Three-level inverter has been widely used in electric drives and renewable power generation system. However, the common mode voltage (CMV) and output current ripple reduction of three-level inverter should be carefully regulated for the appropriate operation. As these two targets are mutually interrelated, the conventional space vector modulation (SVM) scheme cannot cope with them decently. To overcome this drawback, this paper proposes a novel modified SVM scheme to realize CMV and current ripple reduction simultaneously. The generating mechanism of output current ripple is analyzed, and the relationship between current ripple and utilized vectors is quantitatively described. Based on the analyses, the proposed optimal current ripple and CMV reduction pulse width modulation (OCR-CMVRPWM) method adopts four voltage vectors (large, medium, small and zero vectors) to reduce root mean square (RMS) value of current ripple by allocating the sequence and dwell times of utilized vectors. Compared to the existing PWM methods, the proposed OCR-CMVRPWM scheme can reduce the peak of CMV to half of value using the conventional SVM, and obtain a significant reduction of output current total harmonic distortion (THD). The effectiveness of the proposed method is validated by both simulation and experimental results.

Existing high step-up dc–dc converters suffer from various issues, including limited voltage gain, high voltage stress on semiconductors, using a large number of components, and high current ripple. To solve these issues simultaneously, some of the new converters have been proposed recently, which must be improved by the new ones. Hence, this article presents an ultrahigh step-up converter with the objective of maximizing the potential use of renewable energy sources (RES). The suggested converter employs a quadratic boost converter (QBC), a switched capacitor network, and a three-winding coupled inductor to produce a substantial gain in voltage while ensuring continuous current in the input and a common ground between load and source. The voltage stress on semiconductor components has been minimized by the placement of the coupled inductor. Comparative analysis showcases the converter’s superior voltage gain capability compared to the currently introduced step-up dc-dc converters. The converter requires the minimum inductance in order to remain capable of supporting the load with minimal input current ripple, ultimately reducing power loss. The validity of the theoretical analysis of the converter is subsequently proven through experimentation on a prototype with a rated value of 200Woutput power, 20V input voltage, and 400V output voltage.

Single‐stage interleaved Boost‐LLC AC‐DC converters offer advantages such as high power capability, low cost, and reduced input current ripple. However, they typically encounter high bus voltages under universal input conditions when operating with pulse frequency modulation (PFM). To address this issue, three hybrid PFM/pulse width modulation (PWM) control strategies are proposed: output voltage feedback (Strategy I), bus voltage proportional feedforward (Strategy II), and dual‐loop feedback control (Strategy III). Corresponding optimal parameter designs are also conducted based on the principle of power balance. With the aforementioned control strategies and their optimized designs implemented, the bus voltage is effectively maintained within a reasonable range throughout the full input voltage range. Meanwhile, soft switching of the primary switches and secondary rectifier diodes is achieved. Experimental validation on a 300‐W prototype (85–265 V input, 48 V/6.25 A output) demonstrates that the proposed solutions achieve a bus voltage below 550 V, power factor (PF) above 0.98, and peak efficiency exceeding 92.8%. Furthermore, the performance differences among the three strategies are discussed and analyzed in detail.

The output from solar panels, batteries, and other miniature DC sources supply current at low voltages. In order to use this output for certain applications, voltage has to be boosted. This paper presents a high gain DC-DC converter with two-phase interleaved input to reduce input current ripple. A voltage lift capacitor is used to add the outputs of interleaved stages. The output of the interleaved stage is given to a hybrid switched capacitor block, consisting of two diodes and two capacitors. The advantage of the proposed topology is that a high gain is obtained with moderate duty cycle, reduced input current ripple, relatively lower switching stress and without using coupled circuits. The advantages of this converter topology makes it an attractive option for automobile applications and fuel cell based power systems, that are employed in smart grids. The results of the SPICE simulation of the proposed converter are presented to prove its validity.

A high step-up DC-DC converter with three-winding coupled inductor and clamp capacitor is proposed in the paper. The three-winding coupled inductor and voltage doubler are used to increase the voltage conversion ratio without an extreme duty ratio. The input current is operated at continuous conduction mode (CCM) with reduced input current ripple; the lifetime and reliability of the input filter can be improved accordingly. Clamp capacitor in the proposed converter is to clamp and reduce the voltage stress of active switch. The active switch with low power-rating and low on-resistance can thus be employed to reduce switching and conduction losses. In the proposed circuit, the leakage energy can also be recycled to the output capacitor at the load terminal and the reverse-recovery problem of output diode can be alleviated to increase the efficiency. Simulated and experimental results have been presented to verify the effectiveness of the proposed circuit.

Plug-in hybrid electric vehicles (PHEVs) consist of a front-end boost rectifier, which incorporates a power factor correction (PFC) circuit for battery charging. Bridgeless interleaved (BLIL) PFC boost converter topology is proved as a standard PFC converter as it has high efficiency, reduced input current ripple, and reduced electromagnetic interference (EMI). This paper proposes a digital nonlinear control technique that employs a resettable integrator to shape the input current of the converter in phase with the input voltage to achieve high input power factor. This control approach rejects power source and load perturbations better than linear feedback control methods. This is accomplished by summing up the sensed input current of a BLIL converter with a fictitious current synthesized with the input voltage. In this work, a BLIL converter is analyzed for its input power factor improvement, voltage stress across the devices, and dynamic response under variable supply and load conditions using simulation. The hardware is tested for a 300 W BLIL boost converter to validate the simulated results. The performance of the proposed controller is compared with that of conventional average current mode control. The experiment and simulation results prove that the resettable integrator controller shows a better performance than the conventional controller.

Resonant switched capacitor voltage multiplier with interleaving capability

Microgrid is an interconnection of renewable energy sources, loads, power electronic interfaces and energy storage devices. Renewable energy sources are intermittent in nature, and therefore, there is a need for energy storage devices to ensure continuous power supply to the load. Power electronic converters are required to interface the DC bus with energy storage devices. In this work, a bidirectional interleaved switched capacitor DC–DC converter is proposed as a power electronic interface for microgrids. The renewable energy source supplies energy to the load and charges the energy storage device when it is available. The stored energy in the energy storage device supplies energy to the load when the renewable energy source is not available. This is achieved by the proposed converter as it operates bidirectionally. The interleaving technique is carried out at the input side of the converter which reduces the input current ripples. The proposed converter has the following advantages: (i) reduction of ripple current, (ii) reduced voltage stress and (iii) extensive voltage gain and efficiency. It operates in both boost (step-up) and buck (step-down) mode. A 3 kW solar-powered microgrid with bidirectional interleaved switched capacitor DC–DC converter is designed and simulated in MATLAB. The simulation results are associated with the theoretical results obtained from MATLAB.

This paper presents a zero voltage and zero current switching (ZVZCS), dual, two-transistor forward converter (DTTFC) for high input voltage and high power application. Two identical two-transistor forward converters (TTFC) are connected in series and coupled through a single transformer using two primary windings, because of which it operates like a full bridge and makes it suitable for high power application. It imposes only half the input voltage across each of the four switches. This DTTFC has advantage of high reliability as compared to the full or half bridge converters. A modified pulse width modulation (PWM) controller is proposed for DTTFC to minimize the circulating RMS current flowing through the transformer and switching devices. This is without any extra hardware in series with primary of the transformer or in secondary. Conduction losses, being proportional to the square of the conducting current in a transformer and MOSFET, are important in high power converters operating at high currents. Since switching losses are also important in high frequency switching application, in DTTFC two switches, out of four switches, are turned-on and off at zero voltage condition due to the current in leakage inductance of a transformer. The remaining two switches are turned-off at zero voltage and turned-on at zero current condition due to transformer leakage inductance and minimized circulating current, over a wide range of load current. The advantages of this simple circuit topology is high efficiency, high reliability, low component count, and low cost, makes the new converter attractive for high input voltage, high power applications. In this paper we discuss the operating states, switching transitions, method of control, experimental results and associated waveforms of a MOSFET based practical 60 V, 50 A, 100 kHz, dual, two-transistor forward DC-DC converter operating at 750 V input bus. The measured efficiency was 95.07% at full load with maximum efficiency of 96.6% at 70% load.