Current Ripple Cancellation Research Articles

An Interleaved Current-Fed Integrated LLC Resonant Converter With Input Current Ripple Cancellation

An Interleaved Current-Fed Integrated LLC Resonant Converter With Input Current Ripple Cancellation

An Equalization Current Ripple Cancellation (ECRC) Converter-Based Centralized Equalization System for Series-Connected Battery Strings

Battery equalization management is a key technology to ensure the high-performance and safe operation of electrified transportation such as electric vehicles and electric aircraft. In this paper, an equalization current ripple cancellation (ECRC) converter for centralized equalization system is presented. Compared with traditional methods, the ECRC converter-based equalization system achieves a zero-ripple equalization current, so that the unfavorable influence of larger current pulsation on battery cells is eliminated. Meanwhile, under a phase-shifted PWM modulation strategy, the ECRC converter not only implements zero-voltage switching (ZVS) of all switches to reduce switching loss, but also decreases the peak current of the transformer to reduce transformer loss, so that the efficiency of the equalization system is significantly improved. Besides, the value of each power element in the converter is comparatively small, which is conducive to improving the power density of the centralized equalization system. To confirm the theory analysis, an experimental prototype based on a battery string containing 13 cells is built for experimental verification, and a systematic comparison is implemented with existing centralized equalization methods. The experimental and comparison results verify the design of the proposed equalization system and reflect the obvious performance improvement over traditional methods.

A Single-Switch Soft-Switched High Step-Down Zeta Converter With Low Output Current Ripple

This article proposes a new nonisolated high step-down converter that is derived from Zeta converter. By employing coupled-inductor technique, zero-current switching is achieved for the switch at 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> . Also, introduced converter incorporates a current ripple cancellation cell, which provides dc output current for full load as well as light load. Another main feature of the proposed converter is using a single switch and a magnetic core. Therefore, high efficiency and high power density are attained. For further efficiency improvement, a synchronous rectifier is employed, which results in efficiency greater than 96% for the entire load range. A 100-W prototype of the proposed converter is designed and implemented to verify the theoretical analysis and confirm its efficiency improvement and advantages.

GaN-based step-down power converter and control strategy for hydrogen energy systems

The conventional Si-based semiconductors suffer from low switching frequency, high conduction loss and low efficiency. These shortcomings hinder the improvement of power electronic power converter performance. An attractive solution is to replace Si-based semiconductor devices with the wide-bandgap semiconductors based on gallium-nitride material. In terms of the step-down converters which are used for hydrogen energy systems, it is difficult for the traditional buck circuit to eliminate the output current ripple and achieve fault-tolerant operation. Therefore, topologies of the step-down power converter also need improvement. In this paper, a GaN-based step-down power converter and control strategy for hydrogen energy systems is presented. Firstly, the mathematical analysis of the conventional buck converter is done to clarify why it has limitations regarding the reliability and current ripple. Another alternative solution is discussed but still suffers from ripples. In order to eliminate the current ripple and enhance the fault-tolerant ability, a novel GaN-based solution is given and both analysis and design are provided. The current ripple can be perfectly cancelled and fault-tolerant operation can be fully achieved. The comparison is carried out with the existing solutions. The time-domain simulation tests are carried out. And the experimental prototype is established based on the enhancement mode GaN transistor. The experimental results verify the effectiveness of proposed design regarding the current ripple cancellation and dynamic performance.

A combinable wireless power transfer design for extensible-capacity and adaptive charging of route UAVs with active ripple mitigation

This paper presents a combinable wireless power transfer (WPT) system for unmanned aerial vehicles (UAVs) with autonomous and adaptive charging of extensible capacity. By combining multiple transmission modules in parallel to power the UAV, the charging capacity of the system is dramatically enhanced and is adaptive to multiple power ratings with more flexibility. Meanwhile, the combination provides an approach for the system to improve reliability as each module can be operated independently. The mapping relationship between the transmitter (Tx) and the receiver (Rx) is investigated to estimate the amplitude and phase of output currents from the primary side. An active current ripple mitigation scheme based on real-time current estimation is proposed to regulate the Rx currents from the primary side and mitigate the synthetic current ripple without massive sensors onboard, by utilizing the interleaving technique, the output can achieve current ripple cancellation. And the experiment of a scaled-down prototype verifies that the output power of the combinable configuration is boosted up by 145.5% compared with that of a single module, meanwhile, the active ripple mitigation can indeed ameliorate the charging performance and prolong the battery life, the synthetic ripple amplitude is weakened remarkably by 79.06% whereas the efficiency is measured 5% higher than the system without ripple mitigation.

Single‐switch coupled‐inductors‐based high step‐up converter with reduced voltage stress

AbstractThis paper proposes a non‐isolated DC‐DC high step‐up converter. To achieve a high voltage conversion ratio and overcome the problems related to near unity duty‐cycle of the conventional boost converter in high step‐up applications, coupled‐inductors along with switch‐capacitor techniques are merged in this topology. The proposed converter provides continuous input current with low ripple without using any current ripple cancellation method and the voltage across the switch is limited inherently. In order to reduce the control circuit complexity, the proposed converter uses only one switch. These features decrease the complexity of the proposed converter structure. The voltage stress of the semiconductor components is reduced significantly; thus, high‐quality elements (fast power MOSFET switches with low on‐state resistance and Schottky diodes with low forward voltage drop along with low power losses) can be used, which minimizes the switching and conduction losses and improves the converter efficiency. To confirm the converter operation and theoretical analysis, a 200‐W prototype converter with 24‐to‐200‐V input and output voltages operating at 100‐kHz is implemented in the laboratory.

Fully Soft-Switched Non-Isolated High Step-Down DC–DC Converter With Reduced Voltage Stress and Expanding Capability

In this article, a fully soft-switched expandable high step-down dc–dc converter is presented. In order to achieve a high step-down voltage conversion ratio and low component count, the synchronous buck and Cuk converters are integrated. Lower switches’ voltage stress is realized by splitting the input voltage, which can considerably decrease the switches’ conduction loss. Moreover, switching losses along with the reverse recovery problems are mitigated due to the soft-switching operation of all semiconductor devices. The switch utilized for soft-switching operation is also used to replace the output diode as a synchronous rectifier, which reduces the conduction loss. The mentioned features have considerably contributed to the converter efficiency. Furthermore, the converter shares a common ground between the input and the output, which is desirable in many applications, while the converter output current is continuous without adding current ripple cancellation methods. Finally, the number of converter cells can be expanded or reduced; therefore, the converter can be applied to a wide range of loads. The operating principles and analysis of the proposed converter are presented, and the results from the implemented prototype are provided to verify the converter operation and performance.

Novel Soft-Switched Three-Phase Inverter With Output Current Ripple Cancellation

A novel three-phase dc–ac full-bridge soft-switched inverter topology is proposed in this article that provides an ultralow ripple output current. The proposed circuit utilizes a passive filter that comprises a transformer, an inductor, and a capacitor for achieving soft switching and output current ripple cancellation. Zero-voltage switching (ZVS) is achieved at turn <sc xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">on</small> time instant for all the switches in the proposed circuit. The magnitude of ZVS current is optimized throughout the line cycle by the application of the variable frequency modulation technique. In addition to soft switching, an ultralow ripple output current is achieved due to the current ripple cancellation property of the proposed circuit. The output current ripple cancellation is achieved by combining the inverter current with an additional high-frequency ripple current generated by the passive filter. The soft-switched inverter operation and inherent current ripple cancellation achieved by the proposed circuit, result in a high power conversion efficiency. Theoretical analysis and the improvements in inverter performance presented in this article are validated through the experimental verification of the proposed converter topology using a <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$\mathbf{600\text{-}W}$</tex-math></inline-formula> lab prototype.

High step-up-coupled inductor SEPIC DC–DC converter with input current ripple cancellation

High step-up-coupled inductor SEPIC DC–DC converter with input current ripple cancellation

Differential Evolution Based Algorithm for Optimal Current Ripple Cancelation in an Unequal Interleaved Power Converter

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 flicker-free decoupled ripple cancellation technique for LED driver circuits

Light-emitting diode (LEDs) even though are the major lighting source, they suffer from flickering which has adverse effects on human health. With this wide increase in usage, more focus has been on minimizing the ripples, which is the root cause of flickers in LED driver circuits. Initial solution of electrolytic capacitor suffers from shorter lifetime, bulky weight, and high risk of fault. In this regard, a series current ripple cancellation (RC) technique has been proposed in this paper for flicker free operation. The key features of the proposed RC method include unity power factor (UPF) at source end, simple control, and reduced smoothing capacitance value. The proposed system has been validated in both MATLAB/Simulink environment and experimental investigations. Further, detailed analysis and comparative evaluation with the state-of-the-art work reported in the literature has been presented.

Interleaved Single-Stage LLC Converter Design Utilizing Half- and Full-Bridge Configurations for Wide Voltage Transfer Ratio Applications

Automotive on-board dc-dc converters are required to operate over a wide input and output voltage range depending on the state of charge of the input and the output battery. Conventionally, the unidirectional power transfer between these batteries is enabled by a two-stage converter concept. A first-stage nonisolated dc-dc converter regulates the input voltage of the galvanically isolated second-stage dc-dc converter such that the second-stage converter operates in its optimum operating point. This article presents a single-stage interleaved LLC resonant converter of 3.6 kW for this purpose. While LLC converters are usually not suitable to cover such a wide voltage range (the input voltage between 240 and 420 V and the output voltage between 8 and 16 V), this LLC converter is operated in a full-bridge mode for large gains and in a half-bridge mode for low gains. For intermediate gains and loads, the LLC employs the phase-shift mode. To operate the interleaved LLCs at equal switching frequencies enabling output current ripple cancellation to reduce the output capacitor, again, the phase-shift mode is utilized to balance the power transfer during the full-bridge mode while the asymmetrical duty-cycle mode is proposed for power balancing during the half-bridge mode. This article analyzes the converter design for these modes of operation and provides a comprehensive design procedure allowing the designer to simultaneously analyze all stress values for various resonant tank designs. A 3.6-kW prototype employing Si superjunction MOSFETs achieves a power density of 2.1 kW/L. The maximum efficiency reaches 96.5%, while for most operating points, it is kept well above 90%. The experimental measurement results validate the analysis and show that phase-shift operation and asymmetrical duty-cycle modulation can be utilized for power balancing for full-bridge and half-bridge configurations, respectively, such that a much smaller output capacitor can be employed.

DC-Link Current Harmonic Mitigation via Phase-Shifting of Carrier Waves in Paralleled Inverter Systems

DC-connected parallel inverter systems are gaining popularity in industrial applications. However, such parallel systems generate excess current ripple (harmonics) at the DC-link due to harmonic interactions between the inverters in addition to the harmonics from the PWM switching. These DC-link harmonics cause the failure of fragile components such as DC-link capacitors. This paper proposes an interleaving scheme to minimize the current harmonics induced in the DC-link of such a system. First, the optimal phase-shift angle for the carrier signal is investigated using the analytical equations, which provides maximum capacitor current ripple cancellation (i.e., at the main switching frequency harmonic component). These optimally phase-shifted switching cycles lead to variations of the output current ripples, which, when summed together at the DC-link, result in the cancellations of the DC-link current ripples. The results show that when the carrier waves of the two inverters are phase-shifted by a 90° angle, the maximum high-frequency harmonic ripple cancellation occurs, which reduces the overall root-mean-square (RMS) value of the DC-capacitor current by almost 50%. The outcome of this proposed solution is a cost-effective DC-harmonics mitigating strategy for the industrial designers to practically configure multi-inverter systems, even when most of the drives are not operating at rated power levels. The experimental and simulation results presented in this paper verify the effectiveness of the proposed carrier-based phase-shifting scheme for two different configurations of common DC connected multi-converter systems.

A High Step-Up/Step-Down Input-Parallel Output-Series ZVS Bidirectional Converter With Coupled Inductors

This article introduces a nonisolated bidirectional converter with high-voltage conversion ratio. In the proposed converter, by integrating the two-phase low-voltage-side (LVS)-parallel high-voltage-side (HVS)-series bidirectional converter with the coupled inductors, features, such as high voltage gain, low voltage stresses, current sharing, and current ripple cancelation, are achieved. Due to the proposed converter's operation in triangular conduction mode, the desirable benefits of zero voltage switching, diode reverse recovery elimination, and reduction of converter filter inductors and, consequently, leakage inductors are obtained. To recycle the leakage inductors’ energy and to solve the related difficulties for both operation modes, a simple passive clamp with the minimum number of elements is utilized. Also, to improve the light-loads’ efficiency, the variable frequency control is developed. The proposed converter is comprehensively analyzed, and to verify the analysis, the experimental results are provided.

A Novel Current Sharing Scheme for Two-phase Interleaved LLC Converter Based on Virtual Controllable Voltage Sources

In this letter, a novel current sharing scheme for two-phase interleaved LLC converter based on virtual controllable voltage sources (VCVSs) is proposed. In each phase, the VCVS is constructed by an auxiliary winding of the other phase transformer inserted into the resonant tank. The equivalent input voltage of resonant tank, which is the composition of the equivalent ac input voltage and VCVS, can be regulated to achieve current sharing by modulating the phase-shift angle between the two phases. Meanwhile, good output current ripple cancellation effect can be naturally achieved with appropriate parameters of VCVSs. Detailed operation principle and design considerations of the proposed current sharing method are presented. Finally, a 12 V/40 A two-phase interleaved LLC prototype has been built up to verify the theoretical analysis.

High Step-Down Nonisolated DC–DC Converter With Coupled Inductors

High step-down nonisolated dc–dc converter with coupled inductors is proposed. The converter is used a simple lossless clamping circuit. Moreover, it produces the current ripple cancelation at the output due to series connection between the coupled inductors and the output. Automatic current sharing is done in the proposed converter even if the switches have different duty cycles. The proposed converter has lower voltage stress in comparison with traditional Buck converter and also different topologies of Buck converters with the coupled inductors. Besides, the current stress on semiconductor devices is reduced due to the interleaved structure. Finally, the converter has lower number of components in comparison with the similar structures. The mentioned advantages candidate the proposed converter to apply in photovoltaic system. A 200-W laboratory prototype converter is considered and constructed. The experimental results presented confirm the aforementioned features and theoretical analysis.

Discrete-Time Modeling and Control of Double Dual Boost Converters With Implicit Current Ripple Cancellation Over a Wide Operating Range

This article introduces discrete-time controllers for double dual boost converters, suitable for renewable energy applications. The proposed schemes are based on a current ripple mitigation technique, which enables an unconstrained input-to-output voltage converter gain. This is in contrast with classical interleaved topology implementations, where duty cycles are restricted (e.g., to 50%). A discrete-time small-signal controller is proposed for those applications that require nominal specifications. This control strategy is based on a novel linear difference system approach, whereas gain tuning is performed via numerical computation of linear matrix inequalities. In addition, a discrete-time large-signal controller is proposed for those applications that require trajectory tracking. The proposed controllers, their stability, performance, and ripple cancellation properties are validated via experimental results.

Integrated Magnetic Buck–Boost Converter With “Zero” Output Current Ripple

This article presents an integrated magnetic buck-boost converter (IMBBC) with a positive output voltage. The input inductor, two power transfer inductors, and an auxiliary inductor in the ripple cancellation network of this converter are integrated in one magnetic core, and an additional capacitor is included for output current ripple cancellation. The IMBBC inherently operates in the continuous conduction mode and exhibits a nonpulsating input current and a very low ripple output current, thereby not only decreasing the current stress on both the input and output capacitors but also reducing the output voltage ripple. Because the input of the IMBBC is connected to the output during the switch-on period (similar to the operation of buck converters), the proposed IMBBC overcomes the right-half-plane zero problem in the buck or boost mode, thus achieving a higher dynamic performance. The use of the magnetic integration technique not only helped realize the aforementioned performance, but can also help reduce the weight and volume of dc-dc converters. Finally, the feasibility and effectiveness of the proposed topology and design approaches are experimentally verified.

Research on low input current ripple two‐stage converter for low frequency pulsed‐power applications

In this study, a two-stage cascaded pulsed power converter based on the proposed optimised control scheme has been presented. In order to eliminate the low-frequency input current ripple, the front-stage converter only needs to provide average power and the second-stage converter provides pulsed power. Meanwhile, the isolation of energy transfer mode combines with the proposed optimised control method based on the input current AC signal feedback control guarantee smooth input power with low repeat frequency pulsed load. To demonstrated the effectiveness of the proposed low-frequency input current ripple cancellation technique, a 1 kW peak pulsed power prototype is built and tested. The experimental results verify the validity and reliability of the two-stage isolated pulsed power converter with proposed optimised control method, and the proposed methods and concepts in this study can also be applied to all kinds of pulsed power applications.

An Improved Floating Interleaved Boost Converter With the Zero-Ripple Input Current for Fuel Cell Applications

In this paper, an improved floating interleaved Boost converter is proposed for fuel cell applications. In order to achieve zero-ripple input current and keeping others merits such as high voltage gain and low voltage stress of the conventional floating interleaved Boost converter (FIBC) unchanged, a pair of input current ripple cancellation networks composed of a small inductor and a small capacitor are added into the conventional FIBC. Then, the operating principle and the steady-state and dynamic performances of the proposed converter are performed and compared with the conventional FIBC. Finally, a 240 W experimental prototype has been created for further evaluating the expected performances of the proposed converter. The simulation and experimental results demonstrate that the input current ripple of the proposed converter can be totally removed in all power range without significantly increasing the current stress and power loss.