Output Voltage Ripple Research Articles

Maximum Power Point Tracking Performance Benchmarking of High Step-Up DC-DC Converters

Since renewable energy sources (RESs) such as photovoltaic (PV) and wind energy have low output voltage and intermittent output power, they are frequently equipped with step-up DC-DC converters to boost the output voltage and extract maximum power. In this study, maximum power point tracking (MPPT) performance comparisons of high voltage gain DC-DC converters, which are frequently used in PV-powered systems, have been presented. Three different high gain step-up DC-DC converter topologies: (i) quadratic boost converter (QBC), (ii) three level boost converter (TLBC), (iii) stacked boost converter (SBC) have been analysed under MPPT mode that uses the Perturb and Observe (P&O) algorithm. 5.11 kW PV-powered system has been modelled in the MATLAB/Simulink environment for each converter considering the same design specifications such as; 10 kHz switching frequency, 1 mΩ Ron resistance. The related topologies have been simulated under different irradiances: 1000, 900, 850, 750 and 700. Performance results of the aforementioned topologies have been compared in terms of the maximum power of PV panel, the energy efficiency of converters, output voltage ripple and output current ripple. The results reveal that; the TLBC extracts maximum power from PV panels with the converter efficiency 98.9%. The SBC and QBC extract minimum power from PV panels with the converter efficiency 98.1% and 96.5%, respectively. As a consequence, TLBC topology excels with the maximum power extraction capability and efficiency.

High-Frequency Modelling of Constant On-Time Current Mode Buck Converter and Controller Design by Combining Genetic Algorithm

Constant on-time current mode (COTCM) Buck converters are widely used in power management integrated circuit (ICs) for microprocessors. Small-signal models are necessary tools to design high-quality controllers. Existing models neglect output voltage ripples (OVRs) and spectrum extension caused by switching, which makes significant errors under high control bandwidth. This article adopts Fourier series to describe OVRs precisely. Then, influences of OVRs on COTCM are analyzed. Finally, spectrum coupling from current loop and voltage loop is incorporated to obtain a high-frequency model, and four universal analytical expressions in frequency domain are obtained with the aid of matrix calculation. Based on the proposed model and genetic algorithm, an optimal controller design method is developed. Simulation and experiment validate the accuracy of proposed model and the effectiveness of proposed design method.

Open-Circuit Fault Research on Asymmetric Delta-Polygon 18-Pulse Autotransformer Rectifier Unit for More Electric Aircraft

In aviation aircraft, autotransformer rectifier units (ATRUs) have been widely used as front-end rectifiers. The comprehensive analysis of its operating characteristics under the fault is beneficial to assessing the hazards of the faults and developing a fault diagnosis scheme. This article investigates two types of open-circuit (OC) faults in delta-polygon 18-pulse ATRU, namely, diode OC fault and input OC fault. First, the effects of the diode OC fault on five aspects are quantitatively analyzed: diode conduction angle, output voltage ripple, winding current, input current harmonics, and diode and transformer winding losses. Next, the operating characteristics of ATRU are investigated under input OC fault, and the quantitative effects of the five aspects above are also calculated. Then, based on the affected intervals of dc output voltage, a fault diagnosis idea dealing with two types of OC faults is discussed. Meanwhile, the predictive maintenance objects after the fault location are also summarized. Finally, the simulation and experimental results validate the theoretical analysis and discussion. This work is very significant for guiding the fault detection, fault location, and predictive maintenance of ATRUs.

An Improved Pulse Density Modulation Control for Secondary Side Controlled Wireless Power Transfer System Using LCC-S Compensation

In this article, an improved pulse density modulation (PDM) control for secondary side controlled wireless power transfer (WPT) system is proposed. The LCC-S network is selected for the compensation of the reactive power in the system. In the secondary side, an active rectifier with improved PDM control is used to regulate the output voltage. The output voltage regulation is achieved by changing the pulse density of the rectifier switches. By using the proposed PDM pattern, the input pulse sequence of the active rectifier can be distributed more homogenously compared to the conventional PDM control. Therefore, the output current ripple of the primary side inverter and the output voltage ripple of the active rectifier are reduced. The light load efficiency is also improved compared to conventional PDM control. The soft switching conditions are achieved for inverter and active rectifier switches. The experimental prototype with 150 mm air gap is built to validate the performance of the proposed system. The overall efficiency of the system with the proposed PDM is improved by 1.7% and 9.9% compared to the conventional irregular and regular PDM control, respectively. The output voltage ripple of the active rectifier and the output current ripple of the primary inverter are also reduced at light load conditions with the proposed PDM.

Improved dynamic performance with discrete sampling in digital ACM controlled DC‐DC boost converter with capacitor ESR inclusion

AbstractA classical symmetrical carrier‐based digital Average Current Mode (ACM) control has two sampling choices, peak point and valley point, to control the average inductor current. If it is employed to regulate the DC‐DC boost converter, there will be a difference in the dynamic performance at peak and valley point sampling instants because of discontinuous output voltage ripple due to Equivalent Series Resistance (ESR) of the output capacitor. Therefore, this paper investigates the effect of sampling instant on the dynamic performance of the PWM DC‐DC boost converter in consideration of capacitor ESR. The small‐signal transfer functions of a boost converter for both sampling positions are prominent to analyze each sampling impact on its dynamics. They are derived by using discrete‐time modeling. Further, the choices of sampling instant are investigated related to the RHP zero elimination, voltage stability, and peak‐to‐peak ripple current of the DC‐DC boost converter. The boost converter has improved stability performance by synchronizing the ADC sampling at starting position (valley point) of the symmetrical carrier signal, as evident by the analytical and hardware results of both sampling techniques working from 25% to 100% load working conditions.

Numerical Optimization of the Capacitors Selection in the MSBA Converter to Reduce the Output Voltage Ripple

DC–DC power electronics converters are widely used in many applications, such as renewable energy systems. The multistage-stacked boost architecture (MSBA) converter is a large voltage gain converter whose PWM scheme may reduce a percentage of the output voltage ripple, taking advantage of the symmetry of the voltage signals in capacitors (they are triangular waveforms) to have a symmetry cancelation. The switching ripple is unavoidable; the correct selection of components can reduce it, but this may result in a large amount of stored energy (larger size). The selection of capacitors influences the output voltage ripple magnitude. This article proposes a design methodology that combines a recently introduced PWM scheme with a numerical optimization method to choose the capacitors for the MSBA converter. The objective is to minimize the output voltage ripple by choosing two capacitors simultaneously while ensuring the constraint of a certain (maximum) amount of stored energy in capacitors is not overpassed. The internal optimization was performed with the differential evolution algorithm. The results demonstrate that the proposed method that includes numerical optimization allows having a very low output voltage ripple with the same stored energy in capacitors compared to the traditional converter. In a design exercise, up to 60% reduction was observed in the output voltage ripple with the same stored energy in capacitors.

Performance Analysis and Comparison of Non-Inverting Buck-Boost Converter Using PI, OCC, and Hybrid OCC-PI Control

The study compares and analyses the performance of the one-cycle control (OCC), hybrid one-cycle-proportional integral control (OCC-PI), and the conventional PI control method applied to the non-inverting buck-boost converter. The hybrid OCC-PI control method combines the OCC and PI control techniques to provide a hybrid non-linear closed-loop control technique for regulating the buck-boost converter. The MATLAB/Simulink equivalent system model was simulated with design parameter variations using a wide input voltage range of 9 – 36 V, a nominal output voltage of 28 V, and a fixed switching frequency of 250 kHz to validate the control response speed, reliability, and robustness of the proposed control technique. The simulation results due to input voltage, output voltage, and load variations were carried out whiles recording the settling time, overshoots, efficiency, output voltage, and inductor current ripples due to each applied control technique. The simulation results indicated that the Hybrid OCC-PI control provides better response speed and a lower output voltage overshoot relative to the PI. It also provides better reference voltage tracking compared to the OCC control method.

Optimization Improvement Using Pi Controller to Reach CCCV Method in Lead Acid Battery Load

Solar energy can produce electrical energy with the help of photovoltaics so as to produce sufficient or even excessive supply to the electrical load. Therefore, it is necessary to store electrical energy (battery) from the excess unused energy. However, in the process of charging the battery, it takes a long time to fully charge the battery capacity and damage often occurs due to excessive voltage used. This can reduce battery life. The characteristics of the battery need to be considered so that the charging process can be carried out in accordance with the required provisions. The existence of the CCCV method can speed up the battery charging process with a constant current of 20% of the nominal current of the lead acid battery. To avoid overvoltage, the constant voltage method can anticipate the occurrence of damage. Utilization CUK Converter as charging can reduce output voltage ripple. The PI control on the CUK Converter produces a constant voltage of 13.8 Volts and a constant current of 1.44 Ampere. The average error generated by this system is 0.14%.

Widening the Operating Range of a Wireless Charging System Using Tapped Transmitter Winding and Bifrequency Pulse Train Control

In this article, a subharmonics switching technique named bifrequency pulse train (BF-PT) control for wireless battery charging system with tapped transmitter (Tx) winding is proposed to regulate the output power against the variation of load and coupling coefficient. The tapped Tx winding is spilt into two subwindings: subwinding I is connected to the inverter while subwinding II is in open circuit. The charging current and charging voltage can be acquired by measuring the induced current of subwinding I and the induced voltage of subwinding II, respectively, without dual-side communication. BF-PT control, which contains high- and low-frequency pulse trains, can achieve zero voltage switching over a wide operating range. The high- and low-frequency pulse trains are uniformly distributed to suppress the winding current oscillation and to minimize the output voltage ripple. When the coupling becomes weaker and/or light-load conditions, the switches are operated at the subharmonics frequency to further reduce the average switching frequency of the system. To verify the validity of the proposed method, a wireless charging system with 72 V/3 A output is fabricated. The experimental results confirmed that the proposed method is able to maintain constant current and constant voltage output regardless of the load and coupling variations.

Temperature Characteristic Analysis of the Output Intrinsically Safe Buck Converter and Its Design Consideration

Aiming at the unreliability resulting from ignoring the temperature effect and randomness of switching frequency in the traditional design method of an intrinsically safe Buck converter, a reliable design method based on the minimum frequency and considering the temperature characteristic is proposed. The theoretical design range of capacitance is deduced according to the maximum output ripple voltage and output intrinsic safety performance requirements. Considering the temperature characteristics of the capacitor, the actual maximum and minimum capacitances are obtained corresponding to the theoretical design capacitance within a given temperature range. It is pointed out that the actual minimum capacitance increases with the decrease of switching frequency, while the actual maximum capacitance is independent of frequency. Therefore, it can be deduced that there exists a minimum frequency which can meet the requirements of both output ripple voltage and intrinsically safe performance. When the actual maximum capacitance equals the actual minimum capacitance, the analytic expression of the minimum frequency is obtained. Assuming a capacitance adjustment, the actual working frequency of the converter corresponding to the minimum frequency is deduced. The design flow of an intrinsically safe Buck converter based on the minimum switching frequency considering the temperature characteristic is presented. The correctness of the theoretical analysis and the feasibility of the proposed design method are verified by experimental results. This design method can also be applied to other types of intrinsically safe converters.

Design and Analysis of LLC Resonant Converter With Valley Switching Control for Light-Load Conditions

The LLC converter has been widely used in the power supply industry for its high conversion efficiency. When the output load is low, the LLC resonant converter will substantially increase the operating frequency, thereby reducing the conversion efficiency and exceeding the limited operating frequency of the specification. Thus, burst-mode control is applied to increase the ability of regulation at light-load conditions. Even so, the switching period of power switches still occurs at a high switching frequency. Burst-mode control will also result in an extremely low-frequency output voltage ripple. In this study, a valley switching control (VSC) for the LLC resonant converter at light-load conditions is proposed. The VSC control strategy maintains the output voltage by modulating the pulsewidth signals of drivers and achieves valley switching by modulating the switching frequency. Thus, the VSC strategy can reduce the operating frequency compared with the frequency modulation strategy. Compared with burst-mode operations, the proposed VSC effectively reduces the switching loss and has the advantage of high-frequency output voltage ripple. The VSC increases the efficiency and the power quality of the converter. Detailed analysis and design of the proposed method are described. Experimental results are recorded for a prototype converter with a dc input voltage of 400 <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$V_{\mathrm {DC}}$ </tex-math></inline-formula> , an output voltage of <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$48~V_{\mathrm {DC}}$ </tex-math></inline-formula> , and an output current of 12.5 A.

Design and Implementation of Bridgeless AC/DC PFC Sepic Converter with Valley-Fill Circuit

The continuous requirement to improve power quality has motivated the proposal of several PFC circuit topologies. The conventional AC/DC SEPIC has increased conduction loss due to the presence of bridge rectifier. In order to reduce the conduction loss and to improve the efficiency this research work deals with a bridgeless SEPIC (single ended primary inductance converter) AC/DC PFC integrated valley-fill circuit (VFC). The number of components is reduced compared to the existing topologies. The bridgeless topology results in reduced conduction loss, reduced current stress and improved system performance compared with the traditional SEPIC and the existing topologies. The circuit configuration of the suggested topology has been simulated using MATLAB/SIMULINK. The functional parameters of the projected AC/DC integrated VFC is compared with the conventional SEPIC (Con-SEPIC), con-SEPIC integrated VFC and bridgeless SEPIC in terms of passive component count, output voltage ripple, input current ripple, supply power factor, Total Harmonic Distortion. From the simulation outcomes, it is concluded that the bridgeless topology provides high power factor, reduced ripple and reduced supply current harmonics. The results are validated.

Non-isolated high voltage gain DC to DC converter based on the diode a capacitor switches

&lt;p&gt;&lt;span&gt;Many researchers have put great endeavor to develop DC converter’s designs, into studying how to increase voltage gain with low switching stress and low ripple current. This paper has proposed a circuit to boost the voltage with a high gain conversion ratio. It is a combined adverse parallel two boost conversion. Two inductors are connected on both sides of the input source to decrease the current-ripple of the input current and output sides utilizing the interleaving technique. The proposed converter integrated with an active-network circuit is based on multiplier cells and two output capacitors. The voltage gain and voltage stresses across power semiconductors have been determined using a steady-state analysis. In addition, the input current- ripple and output voltage-ripple are analysis have been reported. This converter's inductors operate in a continuous conduction mode (CCM). The designed converter is capable of achieving significant voltage gain while maintaining a low duty ratio. Furthermore, the active switches and output diodes are under low voltage stress. As a result, low voltage components can be used to decrease conduction loss and cost. Finally, this converter was simulated in MATLAB/Simulink software to verify the theoretical calculations.&lt;/span&gt;&lt;/p&gt;

Integration of Three-Phase LLC Resonant Converter and Full-Bridge Converter for Hybrid Modulated Multioutput Topology

A multioutput dc–dc topology based on hybrid modulation of pulse frequency modulation and the phase shift is proposed in this article. The proposed hybrid modulated multioutput converter is derived from the integration of a three-phase LLC resonant converter and the full-bridge converter. With the hybrid modulation, the multioutput is controlled independently free from cross-regulation and isolated from each other. With the three-phase interleaving operation, the resonant currents can be reduced, and thus, the efficiency will be improved. Furthermore, the output current ripple of the main output voltage is reduced; as a consequence, the lifetime of the output filter capacitor is extended, and the reliability is reinforced. What is more, the number of the power switches is reduced, and the zero-voltage switching of the power switches can be achieved within the entire load range by the proposed integrated topology. All the abovementioned features of the proposed converter will lead to a compact, efficient, and cost-effective design. Finally, a 1.4-kW triple-output laboratory prototype is built and tested to validate the feasibility and effectiveness of the proposed converter.

A new step‐up DC‐DC converter with high gain for photovoltaic applications

AbstractUsing interfacing converters with a high boost factor and high efficiency is essential for utilizing the solar cells energy since these energy sources produce low voltage levels. Although employing a high‐frequency transformer or coupled inductors in such converters results in high gain, these elements increase the weight, volume, and cost and affect the efficiency. This article presents a new topology for DC‐DC converter with a high voltage gain to overcome the mentioned problems. The converter provides a higher voltage gain than conventional structures while it includes only one power switch. The switch is connected to the ground; thus, a simple control circuit is required. Besides, the proposed structure has a low output voltage ripple. In this paper, the operating modes of the proposed topology, the influence of parasitic elements on the boost factor, and the efficiency have been described in detail. These item has been examined by experimental verifications. A 500‐W laboratory prototype confirms the proposed topology. Results demonstrate that the topology produces high efficiency and voltage gain.

An Advanced MPPT Scheme for PV Systems Application with Less Output Ripple Magnitude of the Boost Converter

The purpose of this paper is to enhance the performance and tracking efficiency of solar photovoltaic systems. This aim can be achieved by operating the photovoltaic array at its optimum power and reducing the output ripple problem of DC-DC converters that affect and stress sensible electronic loads. In view of that, an advanced maximum power point (MPP) tracking (MPPT) scheme, which can guarantee zero oscillation tracking of the accessible MPP and less ripple magnitude on the output side of the DC-DC boost converter, is used. Various simulations are carried out under three conditions of solar irradiance variation, namely, standard test conditions (STC), rapid, and Sin scenarios, using the MATLAB/Simulink® environment, to assess and benchmark the robustness of the tracking of the new MPPT scheme over the celebrated Increment of Conductance (INC) MPPT scheme. Based on the simulation results, the proposed scheme can significantly improve tracking accuracy and reduce the magnitude of ripples on both sides of the boost converter compared to the INC scheme. Certainly, the proposed scheme can provide a shorter time response (0.011 seconds) to locate and track the expected MPP, which is 2.55 times less than that of the INC scheme; a zero power magnitude oscillation instead of 15.9 watts of the INC scheme; and six-time minimization of the magnitude of output voltage ripples compared to the INC scheme. Furthermore, the suggested MPPT scheme has the better tracking efficiency in all scenarios; 99.86%, 99.60%, and 99.62% in the STC, rapid, and Sin scenarios, respectively, with an average value of 99.69% compared to the INC MPPT scheme, which has 94.23%, 95.28%, and 97.87% in the STC, rapid, and Sin scenarios, respectively, with a moderate average tracking efficiency of 95.79%. Finally, the accuracy and tracking performance of the proposed MPPT scheme are verified by real-time examination using the RT-LAB simulator. According to the results obtained, the proposed scheme provides the highest tracking efficiency of 99.80% and 97.77% under the STC and sudden insolation change scenarios, respectively, compared to the INC scheme, which shows, respectively, 97.8% and 96.5% under both scenarios.

Analysis and Demonstration of Control Scheme for Multiple Operating Modes of Energy Storage Converters to Enhance Power Factor

Rectifiers are required by the devices connected to the distribution end of the electrical power networks for AC/DC conversion. The line current becomes non-sinusoidal when a capacitor with a significant value is used to mitigate the output voltage ripple. This type of converter emulates a non-resistive impedance to the grid, due to which a bend occurs in the shape of the line current, which results in high total harmonic distortion and a low power factor. For perceiving sinusoidal current, power factor correction techniques are required. A digital controller for parallel-connected buck-boost power factor correctors is presented in this article to maintain a constant output voltage and to deal with circulating currents amongst parallel-connected converters. The proposed digital supervisory controller also regulates the input and line currents to keep them sinusoidal according to the input supply voltage to maintain the high power factor of the system. In this paper, using the differential equations of a buck-boost converter, the duty cycle calculations are performed for both Continuous Conduction Mode (CCM) and Discontinuous Conduction Mode (DCM), which are responsible for providing a unity power factor. A supervisory controller encompasses a feed-forward control algorithm for tuning model parameters for eliminating the harmonics from the line current. The proposed scheme helps calculate duty cycles which provides a unity power factor and minimizes the circulating currents. The proposed method was simulated in MATLAB/Simulink and their digital-hardware validation testing was also performed using C2000 MCU Launchpad.

A non-cascading DC/DC quadratic boost converter with high voltage gain for PV applications

ABSTRACT This paper proposed a new quadratic boost converter featuring a high voltage conversion ratio, high efficiency, and comparatively low inductor currents using reduced redundant power processing and voltage lift configurations for PV applications. The proposed Quadratic Boost Converter (QBC) consists of fewer components and improves voltage gain at a lower duty cycle. Furthermore, the inductor and capacitor are controlled to reduce output current and voltage ripples. The operational modes, steady-state analysis, design aspects, and dynamic modelling of the converter in continuous conduction mode are discussed clearly. The performance of the proposed QBC is compared with different existing converters in terms of component count, voltage gain, voltage and current stress of the switching components, effective index, total switching device power, and component losses. A110W hardware prototype has been developed. The simulation and experimental results of the converter validate its performance and stated benefits. The efficiency curves for the proposed QBC for various load currents are presented, with a peak efficiency of 93.8%.

A High-Gain DC Side Converter with a Ripple-Free Input Current for Offshore Wind Energy Systems

Considering that the distance between offshore wind farms and onshore converters is getting farther and farther, dc transmission becomes increasingly more applicable than conventional ac transmission. To reduce the transmission loss, a feasible solution is using a high-gain dc/dc converter to boost the rectified output voltage to thousands of volts. Thus, a novel single-switch high-gain dc/dc converter with a ripple-free input current is presented in this paper. The structure consists of two cells—a coupled-inductor cell and a switched-capacitor cell. The coupled-inductor cell in the proposed converter provides a ripple-free input current. The switched-capacitor cell provides a high voltage gain. The converter has a simple control strategy due to the use of a single switch. Moreover, the output capacitor is charged and discharged continuously by a 180° phase shift to eliminate the output voltage ripple. A steady-state analysis of the converter is proposed to determine the parameters of the devices. In addition, a 240 W, 40/308 V laboratory prototype at 35 kHz switching frequency has been developed, in which the input current ripple is only 1.1% and a peak efficiency of 94.5% is reached. The experimental results verify the validity and feasibility of the proposed topology.

Design and Study of a Series Active Filter for the 10MW-Level High Power and High Stability DC Power Supply

The output power of high stability dc power supply system, which drives the water-cooled magnet of Steady High Magnetic Field Facility (SHMFF), can reach up to tens of megawatt, so that the circuit usually adopts the realization scheme of Silicon-controlled rectifier plus LC filter. For the improvement of magnet current ripple, a novel series active filter (SAPF) is proposed, which adopts high-frequency switching technology and uses a switching power supply instead of a transistor or transformer in the traditional scheme in series at the output of the main power supply. The novel scheme has advantages of lower control complexity and less power loss, and thus higher engineering feasibility. In this paper, the system topology structure, operating principle and control policy are presented at first. Then the key part of the design is discussed, that is, how to accurately extract the output voltage ripple of the main power supply without delay. At last, a small prototype is made to verify the feasibility of the scheme.