A DC-DC Converter with Zero Low Frequecny Input Current Ripple

Due to power time-varying characteristic of a single phase photovoltaic (PV) grid-connected inverter in grid side, its front-end dc/dc converter tends to draw a large ac ripple current with double grid frequency, which would decrease maxim power point tracking performance of PV side. A novel method is proposed for the low frequency input current ripple analysis of a boost converter in a non-isolated single phase PV inverter, based on back current gain A i (s) (input current to output current) model. Mathematical models with different control schemes are built and derived, which are verified in SABER environment. It is indicated and proved that average current mode control strategy is more effective than voltage mode control and open loop control methods. Design principles are also presented. Simulation and experimental results are provided for model verification. Bandwidth limitation is also discussed and improved with proposed PR controller with A i (s) model.

In this paper, a novel nonisolated interleaved high step-up DC-DC converter is proposed based on the coupled inductor and voltage multiplier cell (VMC) methods. Due to the interleaved structure, its input current ripple is low. The low input current ripple and also high power efficiency make the proposed converter suitable for renewable energy applications like photovoltaic (PV) and fuel cell (FC) power generation systems. The windings of the coupled inductors are combined with VMCs to further increase the output voltage with a low power switch’s duty cycle. This combination also leads to obtaining a flexible voltage gain that can be adjusted by coupled inductors’ turns ratio and power switches’ duty cycle. The voltage peaks over semiconductors are much lower than the output voltage. Therefore, low-rated semiconductors can be used for the implementation of the proposed converter, which can reduce the cost and volume. Generally, high voltage gain, low voltage, current stress of power switches, low input current ripple, high efficiency, common ground between the input and output ports, and a low number of elements are the main benefits of the suggested structure. The operation principle, steady-state analysis, and comparison with other converters are presented to show the advantages of the suggested converter. Also, a prototype is built, and the experimental results are presented to prove the theoretical analysis. This prototype is implemented with 200 W rated power, 25 V∼400 V voltage conversion, and 50 kHz switching frequency. Additionally, the efficiency is measured at 95.3% at the rated power.

A soft-switching boost half-bridge converter with high voltage gain and low input current ripple is proposed in this paper. In the proposed converter, a coupled inductor is used at the boost converter stage to reduce the input current ripple. The half-bridge converter stage provides soft-switching operation and high voltage gain. Also, the reverse-recovery problem of output diodes is significantly alleviated by utilizing the leakage inductance of the transformer. Due to the soft-switching operation of all switching devices, the switching loss is significantly reduced and the high efficiency is obtained. The feasibility and performance of the proposed converter were verified on an experimental prototype

This paper proposes novel bidirectional DC-DC converter that has the advantages of high voltage gain, low conduction losses and low input current ripple. Two paralleled current-fed full bridges are located in the low voltage side (LVS), sharing one voltage-fed full bride in high voltage side (HVS). A quadruple phase-shift control strategy is proposed to reduce input current ripple and conduction loss. The phase shift between the full-bridges of LVS is employed to greatly reduce current ripple and the auxiliary inductors are used to help the lag bridge extend the zero-voltage-switch (ZVS) range. Finally, an 800W simulation prototype is built to verify the proposed converter, the accordance between the analysis and simulation results testify the advantages.

An interleaved buck-boost converter with a wide conversion ratio is proposed in this paper. Two converter cells are used in the porposed converter. One is a single-ended primary inductor converter (SEPIC) and the other is a Cuk converter. Since both converter cells have an inductor and a switch, the input current of the proposed converter has low current ripple by utilizing an interleaving technique. The SEPIC converter cell provides a positive step up/down output and the Cuk converter cell provides a negative step up/down output. Therefore, the proposed converter has also step up/down capability and a wide conversion ratio. The proposed converter has a low input current ripple, step up/down capability, and a wide conversion ratio. Theoretical analysis and performance of the proposed converter were verified on an experimental prototype operating at 100 kHz switching frequency.

This paper presents a nonisolated interleaved dc/dc converter with very high voltage gain and low voltage stress for applications requiring a high voltage gain, such as for interfacing photovoltaic or fuel cell with an inverter. In the proposed topology, the voltage multiplier and switched-capacitor are merged to enhance the voltage gain. This feature along with connecting the coupled inductors in series at the output stage increases the voltage conversion ratio. To reduce the input current ripple, two coupled inductors are connected in parallel for sharing the input current equally, resulting in low conduction loss as well as a smaller capacitive filter. To suppress the voltage ringing that stems from the energy stored in the leakage inductance of coupled inductors, the active clamp circuit is implemented in the proposed converter. By applying an integrated regenerative snubber, the leakage energy of coupled inductors not only is recycled to the output stage but also paves the way for soft-switching including zero voltage switching for switches and zero current switching for diodes. The operation modes, design consideration, and comparison verified by experimental results of a 1-kW laboratory prototype of proposed converter are presented. The switches and diodes are implemented using gallium-nitride (GaN) and silicon carbide (SiC) semiconductors, respectively.

This paper deals with a new single-stage high boost quasi-Z-source inverter based on the active switched Z-impedance network. The proposed inverter provides higher voltage boost factor, draws continuous input current, and shares the same ground between the input source and the bridge inverter. Compared with the traditional enhanced boost (quasi-)Z-source inverters (EB-ZSI/EB-qZSI), for two less inductors, one less capacitor, and one additional active switch used at the impedance network, the output voltage boost factor of the proposed inverter is twice as much as the EB-ZSI and EB-qZSI, which implies that it can use a very higher modulation index to provide improved quality output waveforms. Besides, for obtaining the same dc-ac output voltage gain, the proposed method has lower active switching voltage stress, lower passive component voltage ratings, and lower shoot-through current stress with lower input current ripple. The operation theory analysis, power loss calculation, simulation results, and performance comparison with other high boost impedance source inverters are presented. To verify the operating theory of the proposed inverter, a laboratory prototype based on the TMS320F28335 DSP was constructed and tested with 60 V dc input and ac 110 Vrms phase output. Finally, both simulations and the experimental results confirmed that the proposed inverter has high boost voltage inversion capability.

This paper proposes a new non-isolated single-switch DC/DC converter with an ultra-high voltage gain, low input current ripple, low voltage stress, soft-switching operation, and modular scalability for renewable sources applications. With the help of a Three-Winding Coupled-Inductor (TWCI) and Voltage Multipliers circuits, ultra-high voltage gains can be achieved without needing a large duty cycle. A regenerative clamp capacitor recycles the energy stored in the leakage inductor; thus, the maximum voltage across the single power switch is restricted. Moreover, at the turn-on instant of the power switch, a Zero Current Switching (ZCS) condition is achieved. By designing a resonant tank, the switched current value of the main switch at the turn-off instant is reduced significantly. Additionally, the leakage inductor of the TWCI helps all converter diodes to operate under the ZCS condition. Due to full soft-switching performance, the introduced topology can provide a wide output voltage range under a high conversion efficiency. The steady-state analysis and comprehensive comparisons are provided in this paper. A 160 W prototype with 24 V input and 250 V output voltage is developed to validate the theoretical analysis. Due to ZCS operation and low voltage stress (VDS ≈ 40 V), the power loss portion of the MOSFET is low. Moreover, the maximum voltage stresses of diodes are measured as 40 V, 60 V, 90 V, and 110 V, that are well below the output voltage. Furthermore, at the full-load condition, the input current ripple is about 20 % and the measured efficiency is about 96.3%.

Alternative energy systems (AES) are becoming popular for small scale power generation. Designing the converters which transform the DC power into AC is the main development area of AES. Conventional single-phase voltage source inverter (VSI) uses buck topology which gives lower average output voltage than the input DC voltage. However, where the output voltage requirement is larger than the input DC voltage, such as uninterruptible power supply, fuel cell (FC) and photovoltaic systems, boost inverters are used. The boost inverter applied in this study consists of two boost DC-DC converters, which provides sinusoidal AC voltage output. The key drawback of the inverter lies in its control structure. In this paper, a dual loop control method is applied to ensure pure sinusoidal output voltage with fast dynamic response and low input current ripple. The input voltage of the inverter is assumed to be stable at 48 V considering commercially available FC voltage and the output voltage is regulated at 110 Vrms. In this article, the operating principle, mathematical modelling, analysis and control strategy of the boost inverter is presented. The proposed control strategy is verified with simulation using MATLAB/Simulink®. Simulation results show that the output voltage is 110 Vrms pure sinusoidal and the input current has low ripples.

A new switched-capacitor(SC) DC-DC converter is presented. This converter consists of n ring-shaped capacitors connected by switches. The converter has the following features as compared with conventional SC converters: (1) since only one capacitor is charged at one time, the inrush current and the input current ripple are small; (2) the converter has a smaller number of switches; (3) all floating switches form totem-pole connections with grounded switches, thus driving them is easy; and (4) since the generation of the magnetic field is few, together with some signal processing circuits, it is possible to be implemented in one chip IC form such as a system-on-chip.

This paper proposes an optimal methodology based on the Differential Evolution algorithm for obtaining the set of duty cycles of a recently proposed power electronics converter with input current ripple cancelation capability. The converter understudy was recently introduced to the state-of-the-art as the interleaved connection of two unequal converters to achieve low input current ripple. A latter contribution proposed a so-called proportional strategy. The strategy can be described as the equations to relate the duty cycles of the unequal power stages. This article proposes a third switching strategy that provides a lower input current ripple than the proportional strategy. This is made by considering duty cycles independently of each other instead of proportionally. The proposed method uses the Differential Evolution algorithm to determine the optimal switching pattern that allows high quality at the input current side, given the reactive components, the switching frequency, and power levels. The mathematical model of the converter is analyzed, and thus, the decision variables and the optimization problem are well set. The proposed methodology is validated through numerical experimentation, which shows that the proposed method achieves lower input current ripples than the proportional strategy.

A dual-working-modes-based common grounded nonisolated DC-DC converter with a wide voltage-gain range used for photovoltaic applications is proposed in this paper. The proposed converter can flexibly work in dual modes according to external requirements. One working mode is the complementary mode, and the other is the synchronous mode. In complementary mode, the proposed converter can achieve a low or even zero input current ripple, which avoids the use of large electrolytic capacitors at the input side of photovoltaic systems. In synchronous mode, the proposed converter can obtain a wider voltage-gain range to deal with the situation that the input voltage changes sometimes. Besides, common ground can eliminate possible leakage currents between input and output terminals. Analyses of the operating principle and steady-state calculation are presented. Comparisons of the proposed converter under dual working modes with other step-up DC-DC converters show that the proposed converter has higher voltage gain, lower voltage stress, and lower input current ripple with a common grounded characteristic, which is well suited for photovoltaic systems. Finally, a laboratory prototype of 400V/400W at 35 kHz switching frequency has been developed to verify the validity and feasibility of the proposed converter.

In this paper, a novel non-isolated interleaved DC/DC boost converter is presented in which coupled inductors and a passive clamp circuit are employed. ZCS turn-on condition for main switches is provided, and the stored energy in leakage inductance is recycled by means of a passive clamp circuit. Therefore, the voltage stress across switches is reduced resulting in circuit efficiency improvement. Due to interleaved structure and cross-coupled inductors, the input current ripple is reduced and the input current is continuous. To achieve ZCS turn-on condition, the intrinsic leakage inductance of the coupled inductors is used which leads to improving the power density and reducing the switching losses. In order to confirm the theoretical analysis, a prototype with 30 V input voltage, 300 V output voltage, and 300 W is implemented and tested.

This work has adopted the concept of asymmetric inductor magnetization to develop a new quadratic converter with the advantages like a wide range quadratic voltage gain and low source current ripple. In addition, the proposed high quadratic converter has achieved reduced voltage stress due to the presence of switched capacitor cell at the output side. Initially, the operation of the converter and steady-state analysis, including efficiency calculations, are explained. In addition, the design and selection of converter components are presented along with a small-signal analysis. Further, a comprehensive comparison with recent high quadratic gain converters is presented. The comparison is made with regard to the total component count, voltage conversion ratio, effectiveness index, electric stress, current ripple, switching device power (SDP) rating, and input current ripple factor. Furthermore, the 150 W laboratory prototype is used to verify the performance of the proposed converter in terms of operation, dynamic response, and efficiency, and the corresponding experimental findings are reported. The wide range voltage gain, low current ripple, and low electric stress features of the proposed converter highlight its superiority in fuel cell electric vehicle applications.

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.