Low Input Current Ripple Research Articles

Design and performance comparisons of power converters for battery energy storage systems

SummaryThe use of grid‐connected battery energy storage systems (BESSs) has increased around the world. In the scenario of high penetration level of renewable energy sources in distributed generation, BESS plays an important role to combine a sustainable power supply with a reliable dispatched energy source. Different power converter topologies are employed to connect the batteries to the grid, generally using single‐stage converters. However, the battery voltage changes according to its state of charge, which can introduce great variations in the dc‐link voltage. Therefore, the dc/ac stage converter must have its power switches designed to support this voltage variation. A controllable dc‐link voltage is achieved by inserting a dc/dc converter stage to connect the batteries to the dc/ac stage. Among the dc/dc converters, the interleaved bidirectional converter has been widely used due to the low input current ripple. However, the trade‐off of the insertion of the dc/dc stage is barely explored in the literature. Therefore, this work presents a methodology of analysis, considering the battery voltage variation and its influence on BESS power conversion system design and efficiency. Furthermore, it is proposed a power conversion system design oriented toward the voltage class of power switches and efficiency. The analysis in this study are conducted through the use of a case study approach, incorporating both simulated and experimental results.

A Transformerless Enhanced-Boost Quasi-Z-Source Inverter with Low Input Current Ripple for Stand-Alone RES-Based Systems

The main drawback of DC-source-based renewable energy sources (RESs), such as photovoltaic (PV) panels or fuel cells (FCs), is that the voltage generated by a panel or cell is less than the required voltage for connection to a DC–AC inverter for grid applications. In this paper, a single-switched DC–DC boost converter equipped with a quasi-impedance source inverter (QZSI) with a modified switching model is proposed to increase the output voltage of these RESs and convert it to a fixed AC grid voltage for loads. By changing the position of the inductor in a classic step-up converter and using a switched-inductor block, the input current ripple is significantly decreased, and the reliability and long-life of the input sources are increased, which is the main contribution of this work. The quality of the generated AC voltage and the low amount of total harmonic distortion (THD) in the projected topology are significant, and no overshoot and undershoot have been reported for both output voltages and currents under different operating conditions with variable loads. Theoretical analysis, simulation results, and comparison with similar topologies are examined and a prototype with a power of 200 to 400 watts is presented. Experimental results confirm the theoretical studies.

Common Grounded Wide Voltage-Gain Range DC–DC Converter With Zero Input Current Ripple and Reduced Voltage Stresses for Fuel Cell Vehicles

A dc–dc converter used for fuel cell vehicles should be characterized by a wide voltage-gain range and low input current ripple. In order to meet the above requirements, a new nonisolated dc–dc converter consisting of an active switched-inductor cell, a zero current ripple cell, and a switched-capacitor (SC) cell was proposed in this article. The proposed converter integrates with the advantages of a wide voltage-gain range, zero input current ripple, low voltage stresses across power semiconductors, and common ground structure. Thanks to the use of a zero current ripple cell, not only the input current ripple is reduced but also the energy transfer path of the SC cell is changed, thereby reducing the instantaneous peak current of the SC structure. The operating principles, the characteristics analysis, and the parameter design of the proposed converter are given. In addition, to show the merits of the proposed converter, a comparison study is demonstrated. Finally, a prototype of 400 V, 1000 W/50 kHz is developed to validate the effectiveness of the proposed converter.

A Novel Design With Condensed Component of Multi-Input High Gain Nonisolated DC–DC Converter for Performance Enhancement in Carbon Neutral Energy Application

This article presents a multiport and multioperating DC–DC converter topology with high step-up output. The proposed converter topology includes two input ports and four switches. Compared to the recently developed topologies, the proposed topology utilizes a minimum number of components and produces high voltage gain. Modularity in shape, simple structure, continuous input, and low input current ripple are the other advantages of the proposed topology. The proposed topology enables bidirectional power flow by interchanging one of the diodes with a switch. Due to flexibility in design, the proposed topology presents a possibility for integrating multiple sources as in a renewable energy conversion system. Smooth switching between the operating modes and reduced voltage stress on switching devices are the other advantages. The working principle of the proposed converter is analyzed thoroughly in steady state. A detailed comparison is carried out considering several performance parameters to show the advantages of the proposed converter. With a proposal to extend the multi-input topology for high voltage boosting application, simulations are carried out for the dual input topology in MATLAB/Simulink platform. The performance of the converter is also validated experimentally on a dSPACE1104 control platform.

Interleaved converter with ultra-high voltage gain for DC microgrid application

ABSTRACT In this paper a new non-isolated converter with ultra-high voltage gain is presented. The proposed converter utilises coupled inductors, lift circuits and interleaved technique to convert low-level DC voltages to high-level DC voltages without high turn ratios or large duty cycles. Winding-cross-coupled inductors are employed to raise the voltage ratio. The voltage and current stress of semiconductors are reduced, which causes low conduction losses and improves the efficiency. The way the clamp circuit is used limits not only the spike voltages but also effect on the conversion ratio of the proposed converter and make it larger. The main features of this converter are high voltage gain, low voltage stress of semiconductors, low reverse recovery of diodes, low input current ripple, low conduction loss and high efficiency. A prototype of the proposed circuit is constructed in laboratory at 100 W converting 20 V to 450 V. The experimental results are compared with theoretical analysis which verifies them.

High Step-Up Three-Level Soft Switching DC-DC Converter for Photovoltaic Generation Systems

In this paper, a high step-up three-level DC–DC converter with a symmetric structure for PV application is proposed. The converter has high voltage gain. This is achieved due to the use of two high step-up cells and two resonant paths in its structure. The converter has low input current ripples and the voltage stress across all switches is equal to half of the output voltage. The proposed converter uses simple pulse–width modulation (PWM) to trigger the switches. Hence, the proposed converter benefits from a simple structure and control circuit. All semiconductor devices are turned on/off under ZCS conditions. Thus, the switching losses are decreased, and the total efficiency is increased. The converter is implemented and tested through a laboratory prototype. The experimental results verify the theoretical analysis.

Research on Current Distribution Strategy Based on Interleaved Double Boost Converter

In the new energy DC microgrid system, most of the new energy outputs DC power with a low voltage level and a large fluctuation range, which cannot be directly connected to the network. It needs to be boosted by a DC–DC converter, then connected to the power grid or supplied with a DC load. On the premise that the traditional DC–DC converter cannot meet the requirements of high-power applications, the interleaved dual boost converter (IDBC) has been widely used because of its low input current ripple, low device stress and high-power density. It is necessary to maintain the current balance of each phase of the converter during a heavy load and to improve the efficiency during a light load. This paper analyzes the working principle of the six-phase IDBC and reduces the high order model to the low order model according to the symmetry. Due to the current imbalance caused by the mismatch of the parasitic parameters of each phase, two current distribution strategies are designed for different operating. To balance the current of each phase when the converter is overloaded, the relationship between the phase current, parasitic parameters and duty cycle is analyzed based on the state space average method. The estimated parasitic parameters are used to obtain the duty cycle compensation of each phase to eliminate the current imbalance. In addition, to improve the overall efficiency of the converter when the converter connects with a light load, the optimal power distribution coefficient is obtained according to the parasitic parameters to achieve the optimization of the input power, so as to improve the efficiency of the converter. Finally, the simulation results verify the feasibility and effectiveness of the proposed control strategy.

Soft Switching High Voltage Gain Quasi-Z-Source DC–DC Converter With Switched-Capacitor Technique

Nonisolated high-voltage gain soft-switching dc–dc converter is an ideal candidate for distributed generation system converters. This article proposes a high-voltage gain soft switching quasi-Z-source dc–dc converter. The converter integrates a coupled inductor and switched capacitor into a quasi-Z-source network. Soft switching is achieved for all active devices in the converter by controlling the auxiliary switch <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">S</i> <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">a</sub> . By inheriting the advantages of the quasi-Z-source network and coupled-inductor/switched-capacitor, the converter has high voltage gain, high efficiency, low input current ripple, low voltage spike of main switch, and common ground. In addition, the efficiency of the converter is improved by recycling the energy of leakage inductance, resulting from an inherent active clamp of the main switch. The steady-state operation, voltage relationship, current/voltage stress, and power dissipation of each component of the converter have been analyzed and derived in detail. The properties of the proposed converter are verified by designing a 200 W prototype in the laboratory. When the input voltage is 48 V and the output voltage is 380 V, the converter efficiency reaches 96.92%, while the efficiency is 93% in a hard switching. The key waveforms of the converter obtained from the experiment agree well with the theoretical analysis results.

High step‐up MIMO DC–DC power converter control‐based pole placement

AbstractThis paper introduces a new high step‐up multi‐input multi‐output (MIMO) DC–DC converter control‐based pole placement suitable for photovoltaic system applications. The suggested topology has a high stability current control. Low element number, high voltage conversion ratio, and low ripple input current are the main advantages of the proposed converter. The capability to use several energy resources with different voltage/current characteristics, increase the number of inputs and outputs arbitrary without duty‐cycle limitation, and control each input unit power switch independently are other advantages. The operation principle of the suggested topology, steady‐state analysis in continuous condition mode (CCM), and parameter design are analyzed. A comparison between the suggested topology and other converters is applied. Two‐input two‐output version of the suggested topology in 200 W at an operating 50 kHz switching frequency is analyzed. Finally, the Typhoon HiL‐404 emulating setup is applied to verify the performance and efficiency of the suggested high‐step‐up MIMO DC–DC power converter.

A Quadratic Quasi-Z-Source Full-Bridge Isolated DC–DC Converter With High Reliability for Wide Input Applications

In this article, two configurations of the quadratic quasi-Z-source (Q-qZS) isolated dc–dc converters are presented, namely continuous input current and discontinuous input current configurations. The operating principles and steady state of the continuous input current topology analyzed in this article is characterized with the following features: 1) wider operating range due to buck and boost functions in a single stage; 2) draws continuous input current; 3) low input current ripple compared with other qZS-based isolated dc–dc converters; 4) better reliability and good immunity against EMI noise; 5) common ground between the input source and the inverting bridge; and 6) continuous control over the entire operating range. Compared with other qZS-based isolated dc–dc converters, lower current stresses on active and passive components used are realized. Hence, the total magnetic volume/energy required by the proposed converter is reduced with the potential of achieving high power density. A prototype of 40–140 V input voltage, 300 V output, and 550 W rated power is developed to validate the performance of the proposed converter presented.

A novel hybrid half‐bridge LLC resonant converter with double resonant tanks for high step‐down applications

AbstractConventional half‐bridge (HB) LLC converters have been a good candidate for the first stage in the two‐stage conversion structure because of its high conversion efficiency and high frequency operation ability. However, the voltage gain is only 0.5 exclusive of the transformer, resulting in the reduced efficiency for high step‐down applications. In order to solve this issue, in this paper, a novel hybrid HB LLC converter with double resonant tanks is firstly presented for high step‐down ratio applications. The distinctive features of the proposed converter are as follows: (1) the voltage gain of 0.25 is achieved by incorporating the switched capacitor circuit. Thus, the primary turns number for the transformer is halved compared with conventional HB LLC converters. Correspondingly, the smaller primary side winding losses and transformer volume can be implemented. (2) The power splitting and low input current ripple can be obtained due to the employed double resonant tanks. Thus, the uniform thermal distribution and low input filter capacitance are the second advantage for the proposed converter. (3) Soft switching over the entire operation range still can be maintained with larger magnetics inductance. The detailed operation principles, circuit analysis, and resonant tank design for the proposed converter are introduced and presented. A hardware prototype with 36–60 V input, 3 V/50 A‐output is built to demonstrate the declared features of the proposed hybrid converter.

Design and Analysis of a New Coupled Inductor-Based Interleaved High Step-Up DC-DC Converter for Renewable Energy Applications

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.

Development and Analysis of a Novel High-Gain CUK Converter Using Voltage-Multiplier Units

High conversion gain is often required for the grid integration of renewable energy resources such as PV, fuel cells, and wind. It is desired that the stress across switches is lower when higher voltage gain is attained. Similarly, it is also preferred that the converter can achieve high voltage gain without operating at higher duty cycle values. This article presents a novel high-gain CUK converter (HGCC) that uses voltage-multiplier units. The HGCC is a combination of a modified CUK converter and voltage-multiplier units (VMUs). The converter utilizes a boost converter as an input to the modified CUK converter, resulting in an increase in the gain value. The voltage gain of HGCC is increased further by placing VMUs. Based on its overall design, the HGCC inherits various advantages of the CUK converter, such as continuous input and output current, resulting in low input and output current ripples. A mathematical model is developed for the HGCC, which helps calculate its voltage gain at different stages. The model is developed considering ideal elements without conduction and switching losses. Generalized equations for output voltage and gain are derived for n level converter. A simulation study was performed in MATLAB/Simulink that further highlights the advantages of the HGCC. Voltage stresses across different components and the switching of MOSFET and diodes are studied in simulations. An experimental setup is established for hardware prototyping of the converter and validation with the simulation and Mathematical models.

An Interleaved Bridgeless Single-Stage AC/DC Converter With Stacked Switches Configurations and Soft-Switching Operation for High-Voltage EV Battery Systems

A novel single-stage ac/dc isolated onboard charger with modular stacked switches structure utilizing interleaved control is proposed in this article for high-voltage (HV) battery systems in electric vehicles (EVs). In the proposed converter, modular interleaved bridgeless ac/dc boost converters are integrated with modular <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">CLL</i> resonant circuits through sharing the two legs of stacked switches. With this configuration, the voltage stress across each switch is reduced to half of the dc-link voltage, which makes the circuit applicable for HV battery system (such as 800 V) in EVs. In the proposed design, the integrated interleaved boost circuit modules allow low input current ripple to be achieved. Two step-up resonant circuit modules are then connected to the two interleaved legs with their outputs connected in series at the input of a current-fed high-frequency rectifier. Soft-switching commutation is achieved for all switches and diodes in the proposed converter. The descriptions of the proposed converter and its operating principles will be discussed in this article. A silicon-carbide-based hardware prototype with a rated power of 2.4 kW, 90–135 Vac/800 Vdc system has been tested in the laboratory. Results confirmed that a power factor of 0.97 and a peak efficiency of 97.9% were achieved.

A single‐switch high step‐up Zero Current Switching DC‐DC converter based on three‐winding coupled inductor and voltage multiplier cells with quasi resonant operation

AbstractThis paper presents a nonisolated high step‐up soft switching DC/DC converter with continuous input and output energy, low input current ripple, and low voltage stress of semiconductors. In this topology, passive clamping circuits are used not only to recycle leakage energy but also to successfully alleviate voltage spikes on the active MOSFET. The leakage inductor, on the other hand, solves the output diode's reverse recovery problem effectively. Furthermore, output capacitors are connected in series to supply the output load, resulting in a smaller output capacitor volume. The suggested topology's operational theory, as well as steady‐state analyses, is thoroughly explored. The proposed topology's voltage gain and switch stress are then compared with that of some high‐gain topologies. After this, a prototype circuit with a 20 V input voltage, 340 V output voltage, and 200 W output power is designed to test the proposed topology's accuracy.

High-Gain Compact Interleaved Boost Converter With Reduced Voltage Stress for PV Application

This article proposes an interleaved, highly efficient, high-gain modified boost converter. High-gain and transformerless converter operation makes the converter suitable for integrating photovoltaic (PV) power to standalone dc microgrid. A coupled inductor is used with two diodes and one switch per phase with a common clamping capacitor to modify the conventional boost converter. The common clamping capacitor and the coupled inductor reduce the converter’s component count and size; thus, high efficiency is achieved at a low cost. The proposed converter achieves a high step-up gain and low voltage stress on switches. Interleaved converters are deemed ideal for PV power extraction as they exhibit low input current ripple. A 900-W prototype of a two-phase interleaved modified boost converter is designed and developed to verify the working principle of the converter and performance testing.

A New Continuous Input Current Nonisolated Bidirectional Interleaved Buck-Boost DC-DC Converter

In this paper, a new interleaved bidirectional buck-boost DC-DC converter is proposed. The input current of this converter is continuous and has a low ripple, that cause reduction in the size of the input filter of the converter. Because of these features, this converter is appropriate for renewable applications such as fuel cells and photovoltaic (PV) panels for obtaining maximum power in which the continuity of the input current is essential. The operation principle of this converter is detailed, and its power losses calculation shows the positive effects of the low input current ripple on its efficiency. The input current ripple of the proposed converter and conventional interleaved buck-boost converter has been calculated in detail. In addition, the comparison results of this converter with conventional interleaved buck-boost converters and other similar structures confirm that the proposed converter without utilizing extra components achieves continuous input current with low ripple. Compared with other buck-boost structures, the low input current ripple in the presented converter causes an improvement in its efficiency. An experimental prototype is implemented in the laboratory to confirm the correctness of theoretical analyses.

Presenting of the Magnetic Coupling-Based Transformer-Less High Step-Up DC-DC Converter for Renewable Energy Applications

This study presents a new high step-up converter based on the voltage multiplier cell and coupled inductor for renewable energy applications such as fuel cell and photovoltaic power systems. This converter achieves a high voltage conversion ratio using a coupled inductor and voltage multiplier cell (VMC). The voltage multiplier cell acts as a passive clamp circuit and reduces the maximum voltage across the power switch. The suggested topology has only one power switch in its structure, which leads to low cost and volume. The other benefits of the proposed structure are low components count, low input current ripple, low voltage stress throughout the semiconductors, high efficiency, zero-current switching (ZCS), and zero-voltage switching (ZVS) of diodes. Besides, due to the soft-switching condition of the diodes, the reverse recovery problem can be decreased. To show the effectiveness of the suggested topology, operation survey, steady-state analysis, and efficiency calculation are provided. Additionally, the comparison study with other similar converters illustrates the superiority of the proposed structure. Finally, an experimental prototype with 150 W rated power, 50 kHz switching frequency, and 24 V input voltage is implemented to prove the mathematical analysis and effectiveness of the proposed DC-DC converter.

A Novel Multiphase Interleaved DC-DC Boost Converter with Reduced Input Current Ripple for Renewable Energy Application

This paper presents a new multiphase boost converter with improved input current ripple characteristics. The low input current ripple is important due to its effect on the converter’s efficiency and upstream dc bus noise level. It will further affect other devices connected to the same bus. Furthermore, for battery-connected systems such as renewable energy systems, the low current ripple increases the battery life. The method in this research uses split inductance and capacitance configuration as an input filter. The input filter helps compensating for the rippled converter topology, it reduces conduction-switching noise without affecting transient response, and it minimizes the physical size. Therefore, in this new topology, the use of smaller sized components directly influences the converter's size. Interleaved is used for improved heat distribution on the physical circuit board while retaining the benefits of a multiphase converter. Additionally, the low current ripple implies using smaller sized components that directly affect the size of the converter. A three-phase example of the proposed boost converter will be described, along with the derivation of its state space equations. Compared with the standard three-phase boost, the proposed converter can reduce the input current ripple and the output current ripple by 21% and 43%, respectively.

A New Coupled-Inductor-Based Buck–Boost DC–DC Converter for PV Applications

A new buck–boost converter with coupled inductors is presented in this article. The converter benefits from low ripple input current, simple control (both power switches operate synchronously), common ground sharing between input and output ports, low-voltage stress across the power switches, positive output voltage, and quadratic voltage gain. Since the proposed converter has continuous input current, it is a proper choice for fuel cell (FC) and photovoltaic applications. Operating principles, mathematical calculation for steady-state operation, and small-signal modeling analysis are described in detail. Finally, an experimental 25-20-200 V prototype has been implemented to confirm all the mathematical derivation and aforementioned features of the proposed buck–boost converter.