Output Current Ripple Research Articles

Імпульсні перетворювачі зі зниженою пульсацією вихідного струму

When developing pulse converters, in order to ensure a low level of output current ripples, one should seek a compromise between the overall size of the elements and acceptable losses in them, while taking into account the dynamic characteristics of power sources as closed systems with feedback. Using multiphase pulse converters can help solve the said problem, but will not ensure a low level of output current ripples in a wide range of the duty cycle of the control pulses. This study aims to find a pulse converter topology capable of ensuring the reduction of the output current ripples, while maintaining the power and volume of the structure. The paper demonstrates the relevance of the study of pulse converters aimed at obtaining a low-ripple output current for powering sensitive loads and gives an overview of ways to reduce the ripples and the most common topologies of converters. The authors describe the results of the practical application of the developed experimental stand and analyze the obtained dependences of the output current ripples on the volumes of the power sections of the converters of different topologies under the same power and frequency. Recommendations are given for choosing the type of converter in each specific case in terms of reducing ripples.

A Novel MCIs Dual-Bridge for Plasma Cutting Power Supply With Arc Current Feedforward Compensated Phase-Shift Control

This paper presents a novel multi-stage coupled inductors (MCIs) dual-bridge converter using phase-shifted control strategy with arc current feedforward compensated, aiming to meet the demands of low frequency arc ignition, arc transfer process and multi-mode cutting in plasma cutting power supply. Compared to the conventional half-bridge and full-bridge converters, the proposed (MCIs) dual-bridge converter can significantly suppress the output current ripple, which benefits from inductance coupling and double control frequency. Then, the mathematical model of a multi-stage coupled dual-bridge was built, and phase-shifted control method was studied. Combined with the advantages of (MCIs) dual-bridge converter, the proposed control algorithm with arc current feedforward can solve the arc problems of ignition failure via plasma arc current compensation and pneumatic circuit compensation, which caused by serious current fluctuation during sudden change of air pressure and arc transform frequently in cutting process. To verify the feasibility of the proposed multi-stage coupled dual-bridge converter and control scheme, a 20kW experimental prototype for plasma cutting power supply has been built. The experimental results show that the proposed topology and control scheme help to improve the success rate of arc ignition, reduce the probability of cutting arc breaking, increase the stability of the power supply and enhance the cutting effect.

A New Control Solution Using Fcs-Mpc for a Bidirectional Interleaved Converter Operating as a DC Power-Flow Interface

This work proposes a control solution based on finite control set model predictive control (FCS-MPC) for interleaved converters with the features of maintaining phase currents balanced and reducing the output current ripple while presenting a voltage regulation with a high disturbance rejection capability even under constant power loads. Moreover, the proposed solution adds a penalty strategy in the cost function to prevent overcurrent. Further, this work provides a secondary contribution, consisting of a method to estimate the predictive control bandwidth based on the disturbance rejection capability. The control analysis and the simulation results carried out throughout the work confirm that the proposed strategy solves the main issues of the interleaved converter and ensures the operation for applications in power flow interfacing between dc links.

Finite‐control‐set model predictive control with a constant switching frequency for single‐phase grid‐connected photovoltaic inverter

Taking the advantage of easy implementation in the discrete digital control system, the finite-control-set model predictive control (FCS-MPC) is widely used in multi-phase or multi-level power converters. As the smallest independent operation unit in photovoltaic (PV) distributed power generation systems, the PV inverter has the most direct influence on the power quality. However, the lack of switching states and output voltage levels restricts the development of FCS-MPC in single-phase PV inverters. In order to improve the quality of the PV inverter output current, a constant switching frequency FCS-MPC (CFS-FCS-MPC) method is proposed for single-phase grid-connected PV inverter in this paper, which can thus reduce output current ripples and lower harmonics. Compared with the conventional FCS-MPC method, the proposed CFS-FCS-MPC method synthesizes the switching state with a nonzero and a zero switching state in one sampling period. In addition, an optimum allocation of switching states and execution time for the synthesized switching state is presented. Experimental results have verified the effectiveness of the proposed CSF-FCS-MPC method for the output current, achieving lower current ripples and higher current quality with a constant switching frequency.

Variable Switching Frequency PWM for Three-Phase Four-Wire Split-Capacitor Inverter Performance Enhancement

Three-phase, four-wire, split-capacitor inverters, thanks to their capability to deal with unbalanced systems, are currently employed in photovoltaic installations, electric vehicles battery chargers, active power filters, and many other grid-tied applications. The minimization of ac output current ripple and switching losses positively impacts the inverter's efficiency, volume, weight, and cost optimization. For this reason, a novel variable switching frequency driving strategy independently tunable on each phase is proposed in this article. Taking advantage of phase current ripple prediction, a proper variable switching frequency strategy is applied for obtaining a flat current ripple profile. Having tuned the driving strategy parameters, it is possible to optimize and compare individual metrics such as the maximum peak-to-peak value of the current ripple, current ripple rms, average switching frequency, and switching losses. By applying the proposed modulation method, a significant inverter performance enhancement has been obtained. Converter efficiency is improved without introducing detrimental effects on the current harmonic quality. Analytical derivations are expressed as a modulating index function and the power factor for balanced and unbalanced systems. All the theoretical developments are verified throughout numerical simulations and experimental tests.

Design a H-bridge low ripple and high bandwidth air core magnet corrector power supply in NSRRC

This paper is the study of a low-current-ripple and high-bandwidth corrector power supply. The main circuit of this power supply is using a full bridge (H-bridge) structure, and the output current through the high-precision direct current current transducers (DCCT) to transfer the reference voltage to the controller. Previous TPS corrector power supply had a 4.7 kHz current bandwidth, and its output current ripple was 100 μA. Such current ripple and bandwidth do not satisfy the requirements of a rapidly orbiting feedback system of air core loading. Therefore, our research team designed a novel prototype power supply with a high bandwidth (more than 10 kHz) and low output current ripple (less than 10 μA) which was developed via a novel topology circuit. The operation frequency of the main power switch's n-type metal-oxide-semiconductor logic of this novel circuit is increased to 245 kHz. Moreover, the output results of the filter inductor and filter capacitor are modified to 80 μH and 2.46 μF, respectively. The prototype power supply bandwidth reached 10.546 kHz and increase of 124% and its output current ripple was lowered below than 5 μA. The properties of this corrector power supply are very important for the beam correction in storage rings. Finally, A circuit with an input voltage of 48 V, a maximum output current of 10 A, and an output power of 400 W is tested in a laboratory to verify the performance of the developed corrector for the National Synchrotron Radiation Research Center.

Interleaved phase-shift full-bridge DC/DC converters for an electromagnetic micro-actuator

Two low voltage parallel full-bridges are proposed for the power supply of a two-axis electromagnetic micro-actuator. GaN FETs are chosen for these converters to achieve high efficiency while switching at high frequencies. The control strategy implements the phase shift between two branches of each full-bridge and the interleaved phase between two full-bridges, which reduces the load current ripple and increase the frequency of input and output current ripples. These properties help us miniaturize filtering coils and decoupling capacitors associated to the converters. The test bench that highly integrates the micro-actuator and converters was fabricated. Simulation and experimental results are compared for analysing and validating the integration and the proposed control strategy.

Hybrid Dual-Loop Control for Current Regulation and Low-Frequency Ripple Rejection in Led Drivers

This paper presents a new hybrid dual-loop control system for the DC/DC LLC resonant converter, operating as a downstream DC/DC converter in a two independent stage offline LED driver. The outer loop employs a PI controller to maintain the average LED current regulated at the reference value and reject parametric variation. The inner loop implements an adaptive periodic disturbance rejection (APDR) subsystem, thus conceiving the hybrid PI\&APDR controller. The APDR subsystem is designed to strictly reject the bus voltage ripple and limit its transmission to the LED current. Experimental results show the proposed controller feasibility in achieving good tracking behavior, reduced output current ripple under different bus voltage ripple amplitude and frequency, robustness against parametric variations, and simple implementation and design. For the sake of completeness, the proposed PI&APDR is compared with the conventional proportional resonant controller employing experimental results and extra analysis based on simulations.

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.

Closed-Form Formulas for Automated Design of SiC-Based Phase-Shifted Full Bridge Converters in Charger Applications

Phase-Shifted Full Bridge (PSFB) topology in its four-diode variant is the choice with the lowest part count in applications that demand high power, high voltage, and galvanic isolation, such as in Electric Vehicle (EV) chargers. Even though the topology is prevalent in power electronics applications, no single, unified analytical model has been proposed for the design process of four-diode PSFB converters. As a result, engineers must rely on simulations and empirical results obtained from previously built converters when selecting components to properly match the DC source voltage level with the DC load voltage requirements. In this work, the authors provide a design-oriented analysis approach for obtaining the output voltage and semiconductor current values, ready for implementation in a spreadsheet- or MATLAB-type software to automate design optimization. The proposed formulas account for all the first-order nonlinear dependencies by considering the impact of each of the following eight design parameters: DC-link voltage, load resistance, phase-shift ratio, switching frequency, transformer turns ratio, magnetizing inductance, series inductance, and output inductance. The results are verified through experiments at the power level of 10 kW and the DC-link voltage level of 800 V by using a grid simulator and a SiC-based two-level Active Front End (AFE) with a DC–DC stage based on the PSFB topology. The accuracy of the output voltage formula is determined to be around 99.6% in experiments and 100.0% in simulations. Based on this exact model, an automated design procedure for high-power high-voltage SiC-based PSFB converters is developed. By providing the desired DC-link voltage, output voltage, output power, output current ripple factor, maximum temperatures, and semiconductor and heatsink databases, the algorithm calculates a set of feasible designs and points to the one with the lowest semiconductor losses, dimensions, or cost.

Performances of Photovoltaic System Using Grid Tied Transformerless Inverter

In order to eliminate the common-mode (CM) leakage current in the transformer less photovoltaic (PV) systems, the concept of the virtual dc bus is proposed in this paper. By connecting the grid neutral line directly to the negative pole of the dc bus, the stray capacitance between the PV panels and the ground is bypassed. As a result, the CM ground leakage current can be suppressed completely. Meanwhile, the virtual dc bus is created to provide the negative voltage level for the negative ac grid current generation. Consequently, the required dc bus voltage is still the same as that of the full-bridge inverter. Based on this concept, a novel transformer less inverter topology is derived, in which the virtual dc bus is realized with the switched capacitor technology. It consists of only five power switches, two capacitors, and a single filter inductor. Therefore, the power electronics cost can be curtailed. This advanced topology can be modulated with the unipolar sinusoidal pulse width modulation (SPWM) and the double frequency SPWM to reduce the output current ripple. As a result, a smaller filter inductor can be used to reduce the size and magnetic losses.

Steady-State Control of Fuel Cell Based on Boost Mode of a Dual Winding Motor

In recent years, a dual winding motor drive has been proposed in the field of fuel cell vehicles due to its advantages of good performance and high robustness. This new topology and its basic control method have been widely investigated. However, the previous research has not considered the current dynamic property of a fuel cell when studying the power sharing control method, but this is an important research objective for fuel cell durability. Considering the current change principle of a fuel cell, an optimal steady-state control method based on a new dual winding motor architecture boost charging is proposed to optimize the fuel cell life. In addition, in view of the current circulation problem of the fuel cell side winding in the boost mode, a Bang-Bang-PI control algorithm with a relatively constant reference value is proposed to realize the current sharing control. On this basis, the optimized control of the output current ripple of the fuel cell is realized to ensure the steady-state of the proton exchange membrane fuel cell (PEMFC). Finally, the results show that this method can control the stability of the fuel cell efficiently.

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 double closed loop control algorithm based on current mode in full bridge circuit

In order to improve the problems of large output current and voltage ripples and slow system response when the full-bridge circuit is working. This paper proposes a double closed-loop control algorithm based on current mode. Use fuzzy controller to optimize the parameters of voltage outer loop PID controller. The genetic controller is used to optimize the parameters of the current inner loop PID controller. After the dual closed-loop structure of the current control mode is optimized for the traditional PID controller, the overshoot is reduced, the system response speed is accelerated and the current ripple and voltage ripple are also greatly reduced. The simulation verifies the effectiveness of the designed double closed-loop control algorithm.

Simulation research on phase selection control algorithm of a four-phase interleaved parallel Boost converter

In order to increase the rated power of the DC/DC converter, the interleaved parallel connection is widely used. Although the interleaved and parallel Boost converters can increase the operating power of the system, at the same time, it has the advantages of smaller system output current ripple and can reduce the stress of switching devices, but when the system is running in low power mode, due to the use of multi-phase Boost, the increase in loss makes the conversion efficiency of the system lower. A phase selection control algorithm is proposed in this paper, by which the conversion efficiency of multi-phase interleaved parallel Boost converters can be effectively improved. Finally, the feasibility of the phase selection control algorithm designed is verified through simulation in this paper.

Simulation on staggered parallel boost converter with double integral sliding mode control

As a non-linear input power source, fuel cells have soft output characteristics, slow dynamic response, and short service life. In order to improve the service life of the fuel cell, this paper conducts a simulation study on an interleaved parallel boost circuit based on double integral sliding mode control. The interleaved parallel structure is used to reduce the input current ripple of the fuel cell, and the state space average equation is used for modeling. At the same time, the double integral sliding mode control can improve the dynamic performance of the Boost converter. A hysteresis control is added after the sliding mode control to weaken the chattering effect of the sliding mode control. Matlab simulations show that the interleaved parallel Boost circuit with double integral sliding mode control can control the output current ripple of the fuel cell within 1% and make the output voltage have good dynamic performance.

MODIFIED QUADRATIC BUCK BOOST CONVERTER FOR PV APPLICATIONS

Buck-boost DC/DC converters have been extensively employed in stepping up/down the voltage for PV applications. The input and the output port current of the traditional quadratic buck-boost converter are discontinuous, which result in increased input and output current ripples and complicate the design of the input and output filters. Hence these problems can be solved by using a modified quadratic buck boost converter, which provides wider voltage conversion ratio with continuous input and output ports current. Dual output can be derived from this single input converter for multiple output applications. Also a fuzzy logic controller can be designed for this proposed converter for better and faster performance.

Power Factor Preregulation in Interleaved Luo Converter-Fed Electric Vehicle Battery Charger

This work deals with the design and implementation of a new interleaved Luo power factor preregulator (PFP)-based electric vehicle (EV) battery charger, which is suitable for low-cost and improved power quality (PQ)-based EV charging. By interleaving two Luo converter cells, the input current is divided between them, which provides reliable and efficient charging of the battery at high-power discontinuous conduction mode (DCM) operation. This reduces the switch conduction loss due to reduced device current stress and thus, the charger efficiency is improved. The interleaved Luo converter incorporates low input and output current ripple due to ripple cancellation. This charger operates in constant current mode up to certain battery state of charge (SOC). However, for higher SOC range, it maintains constant voltage charging using a flyback converter at the next stage. Two converters are designed in DCM to provide inbuilt zero current switching and circuit diodes show good reverse recovery. An inherent PF preregulation is obtained at input mains over a wide range of supply voltages as well as dc-link voltage. The total harmonic distortion of input current is obtained as per PQ regulations. Its prototype is built and tested to validate its improved performance over two-stage solutions.

A soft switching four‐phase converter with ultra‐high step down conversion ratio and automatic uniform current sharing

This paper introduces a new high step down four-phase converter with soft switching and automatic uniform current sharing. The phase number of the introduced topology can be expanded. In this converter, the main switches are turned on under zero voltage zero current switching condition and turned off under zero voltage switching. Also, the auxiliary switches and diodes operate respectively under zero voltage switching and zero current switching conditions. In the proposed architecture, the duty cycle is extended and the semiconductors voltage stress is reduced by applying series capacitors and coupled inductors. The leakage energy associated with the coupled inductors is absorbed and the reverse recovery losses of diodes are eliminated. Uniform current sharing between four phases is achieved without any extra current sharing control circuit. Furthermore, by utilizing the interleaved method, the current stress and the output current ripple are reduced. This converter provides above advantages while its input and output grounds are connected. As a result, the introduced topology can provide high step down conversions at high frequencies. The converter operation and its characteristics are analysed in detail. The accuracy of the theoretical analysis is verified by a laboratory prototype.

Design and development of realistic PV emulator adaptable to the maximum power point tracking algorithm and battery charging controller

In this paper, PV emulator is developed using double loop PI controlled DC-DC buck converter. Ambient environmental conditions such as irradiance, temperature and wind speed are considered for creating PV reference model in the PV emulator. The simulation model of the proposed PV emulator is created and tested using MATLAB Simulink package. To validate the effectiveness of the proposed PV emulator, it is tested with different operating conditions such as varying irradiance, temperature and wind speed. The current–voltage and power-voltage characteristic of the PV emulator is compared with PV reference model. The suitability of the PV emulator is tested with MPPT algorithm and battery charging controller in addition to number of objectives. Real time testing of the proposed PV emulator is done experimentally and also corresponding results are discussed. The proposed Solar PV emulator has the following properties: (1) higher bandwidth DC-DC buck converter, (2) extremely reliable performance with lower response time, and (3) lower output voltage and current ripple.