Energies

Research

Jump to: Review

15 pages, 3350 KiB

Open AccessArticle

Decoupled Current Controller Based on Reduced Order Generalized Integrator for Three-Phase Grid-Connected VSCs in Distributed System

by Sen Zhang, Jianfeng Zhao, Zhihong Zhao, Kangli Liu, Pengyu Wang and Bin Yang

Energies 2019, 12(12), 2426; https://doi.org/10.3390/en12122426 - 24 Jun 2019

Cited by 10 | Viewed by 3047

Abstract

Grid-connected voltage source converters (GC-VSCs) are used for interfacing the distributed power generation system (DPGS) to the utility grid. Performance of the current loop is a critical issue for these GC-VSCs. Recently, reduced order generalized integrator (ROGI)-based current controller is proposed, such that [...] Read more.

Grid-connected voltage source converters (GC-VSCs) are used for interfacing the distributed power generation system (DPGS) to the utility grid. Performance of the current loop is a critical issue for these GC-VSCs. Recently, reduced order generalized integrator (ROGI)-based current controller is proposed, such that AC reference signal of positive or negative sequences can be separately tracked without steady-state error, which has the advantage of less computational burden. However, the cross-coupling within the ROGI-based current controller would deteriorate the transient response of the current loop. In this paper, a ROGI-based decoupled current controller is proposed to eliminate the coupling between

α

-axis and

β

-axis. Thus, the faster dynamic response performance can be achieved while maintaining the merits of ROGI-based current controller. An optimal gain parameter design method for the proposed current controller is presented to improve the stability and dynamic response speed of current loop. Simulation and experiments were performed in MATLAB/Simulink and TMS320C28346 DSP-based laboratory prototype respectively, which validated the proposed theoretical approach. Full article

(This article belongs to the Special Issue Design and Control of Power Converters 2019)

► Show Figures

Figure 1

14 pages, 1866 KiB

Open AccessArticle

Nonsingular Terminal Sliding Mode Control Based on Binary Particle Swarm Optimization for DC–AC Converters

by En-Chih Chang, Chun-An Cheng and Lung-Sheng Yang

Energies 2019, 12(11), 2099; https://doi.org/10.3390/en12112099 - 1 Jun 2019

Cited by 6 | Viewed by 2465

Abstract

This paper proposes an improved feedback algorithm by binary particle swarm optimization (BPSO)-based nonsingular terminal sliding mode control (NTSMC) for DC–AC converters. The NTSMC can create limited system state convergence time and allow singularity avoidance. The BPSO is capable of finding the global [...] Read more.

This paper proposes an improved feedback algorithm by binary particle swarm optimization (BPSO)-based nonsingular terminal sliding mode control (NTSMC) for DC–AC converters. The NTSMC can create limited system state convergence time and allow singularity avoidance. The BPSO is capable of finding the global best solution in real-world application, thus optimizing NTSMC parameters during digital implementation. The association of NTSMC and BPSO extends the design of classical terminal sliding mode to converge to non-singular points more quickly and introduce optimal methodology to avoid falling into local extremum and low convergence precision. Simulation results show that the improved technique can achieve low total harmonic distortion (THD) and fast transients with both plant parameter variations and sudden step load changes. Experimental results of a DC–AC converter prototype controlled by an algorithm based on digital signal processing have been shown to confirm mathematical analysis and enhanced performance under transient and steady-state load conditions. Since the improved DC–AC converter system has significant advantages in tracking accuracy and solution quality over classical terminal sliding mode DC–AC converter systems, this paper will be applicable to designers of relevant robust control and optimal control technique. Full article

(This article belongs to the Special Issue Design and Control of Power Converters 2019)

► Show Figures

Figure 1

22 pages, 3425 KiB

Open AccessArticle

Supervisory Control for Wireless Networked Power Converters in Residential Applications

by S. M. Rakiul Islam, Sung-Yeul Park, Shaobo Zheng, Song Han and Sung-Min Park

Energies 2019, 12(10), 1911; https://doi.org/10.3390/en12101911 - 18 May 2019

Cited by 2 | Viewed by 2853

Abstract

This paper presents a methodology to design and utilize a supervisory controller for networked power converters in residential applications. Wireless networks have been interfaced to multiple power factor correction (PFC) converters which are proposed to support reactive power. Unregulated reactive power support from [...] Read more.

This paper presents a methodology to design and utilize a supervisory controller for networked power converters in residential applications. Wireless networks have been interfaced to multiple power factor correction (PFC) converters which are proposed to support reactive power. Unregulated reactive power support from PFC converters could cause reactive power deficiency and instability. Therefore, a supervisory controller is necessary to govern the operation of PFC converters. WiFi and WirelessHART networks have been used to implement the supervisory controller. Different nodes of the power network are connected by wireless communication links to the supervisory controller. Asynchronous communication links latency and uncertain states affect the control and response of the PFC converters. To overcome these issues, the supervisory controller design method has been proposed based on the system identification and the Ziegler-Nichols rule. The proposed supervisory controller has been validated by using a hardware-in-the-loop (HIL) test bed. The HIL testbed consisted of an OP4510 simulator, a server computer, Texas Instrument-Digital Signal Controllers (TI-DSCs), WiFi and WirelessHART modules. Experimental results show that the proposed supervisory controller can help to support and govern reactive power flow in a residential power network. The proposed method of controller design will be useful for different small-scale power and wireless network integration. Full article

(This article belongs to the Special Issue Design and Control of Power Converters 2019)

► Show Figures

Figure 1

19 pages, 1467 KiB

Open AccessArticle

Flatness-Based Control for the Maximum Power Point Tracking in a Photovoltaic System

by Leopoldo Gil-Antonio, Belem Saldivar, Otniel Portillo-Rodríguez, Juan Carlos Ávila-Vilchis, Pánfilo Raymundo Martínez-Rodríguez and Rigoberto Martínez-Méndez

Energies 2019, 12(10), 1843; https://doi.org/10.3390/en12101843 - 15 May 2019

Cited by 17 | Viewed by 4351

Abstract

Solar energy harvesting using Photovoltaic (PV) systems is one of the most popular sources of renewable energy, however the main drawback of PV systems is their low conversion efficiency. An optimal system operation requires an efficient tracking of the Maximum Power Point (MPP), [...] Read more.

Solar energy harvesting using Photovoltaic (PV) systems is one of the most popular sources of renewable energy, however the main drawback of PV systems is their low conversion efficiency. An optimal system operation requires an efficient tracking of the Maximum Power Point (MPP), which represents the maximum energy that can be extracted from the PV panel. This paper presents a novel control approach for the Maximum Power Point Tracking (MPPT) based on the differential flatness property of the Boost converter, which is one of the most used converters in PV systems. The underlying idea of the proposed control approach is to use the classical flatness-based trajectory tracking control where a reference voltage will be defined in terms of the maximum power provided by the PV panel. The effectiveness of the proposed controller is assessed through numerical simulations and experimental tests. The results show that the controller based on differential flatness is capable of converging in less than 0.15 s and, compared with other MPPT techniques, such as Incremental Conductance and Perturb and Observe, it improves the response against sudden changes in load or weather conditions, reducing the ringing in the output of the system. Based on the results, it can be inferred that the new flatness-based controller represents an alternative to improve the MPPT in PV systems, especially when they are subject to sudden load or weather changes. Full article

(This article belongs to the Special Issue Design and Control of Power Converters 2019)

► Show Figures

Figure 1

18 pages, 6393 KiB

Open AccessArticle

High Efficiency Solar Power Generation with Improved Discontinuous Pulse Width Modulation (DPWM) Overmodulation Algorithms

by Lan Li, Hao Wang, Xiangping Chen, Abid Ali Shah Bukhari, Wenping Cao, Lun Chai and Bing Li

Energies 2019, 12(9), 1765; https://doi.org/10.3390/en12091765 - 9 May 2019

Cited by 8 | Viewed by 3933

Abstract

The efficiency of a photovoltaic (PV) system strongly depends on the transformation process from solar energy to electricity, where maximum power point tracking (MPPT) is widely regarded as a promising technology to harvest solar energy in the first step. Furthermore, inverters are an [...] Read more.

The efficiency of a photovoltaic (PV) system strongly depends on the transformation process from solar energy to electricity, where maximum power point tracking (MPPT) is widely regarded as a promising technology to harvest solar energy in the first step. Furthermore, inverters are an essential part of solar power generation systems. Their performance dictates the power yield, system costs and reliable operation. This paper proposes a novel control technology combining discontinuous pulse width modulation (DPWM) and overmodulation technology to better utilize direct current (DC) electrical power and to reduce the switching losses in the electronic power devices in conversion. In order to optimize the performance of the PV inverter, the overmodulation region is refined from conventional two-level space vector pulse width modulation (SVPWM) control technology. Then, the turn-on and turn-off times of the switching devices in different modulation areas are deduced analytically. A new DPWM algorithm is proposed to achieve the full region control. An experimental platform based on a digital signal processing (DSP) controller is developed for validation purposes, after maximum power is achieved via a DC/DC converter under MPPT operation. Experimental results on a PV system show that the DPWM control algorithm lowers the harmonic distortion of the output voltage and current, as well as the switching losses. Moreover, better utilization of the DC-link voltage also improves the PV inverter performance. The developed algorithm may also be applied to other applications utilizing grid-tie power inverters. Full article

(This article belongs to the Special Issue Design and Control of Power Converters 2019)

► Show Figures

Figure 1

22 pages, 11661 KiB

Open AccessArticle

Novel Step-Down DC–DC Converters Based on the Inductor–Diode and Inductor–Capacitor–Diode Structures in a Two-Stage Buck Converter

by Mauricio Dalla Vecchia, Giel Van den Broeck, Simon Ravyts and Johan Driesen

Energies 2019, 12(6), 1131; https://doi.org/10.3390/en12061131 - 22 Mar 2019

Cited by 7 | Viewed by 4250

Abstract

This paper explores and presents the application of the Inductor–Diode and Inductor-Capacitor-Diode structures in a DC–DC step-down configuration for systems that require voltage adjustments. DC micro/picogrids are becoming more popular nowadays and the study of power electronics converters to supply the load demand [...] Read more.

This paper explores and presents the application of the Inductor–Diode and Inductor-Capacitor-Diode structures in a DC–DC step-down configuration for systems that require voltage adjustments. DC micro/picogrids are becoming more popular nowadays and the study of power electronics converters to supply the load demand in different voltage levels is required. Multiple strategies to step-down voltages are proposed based on different approaches, e.g., high-frequency transformer and voltage multiplier/divider cells. The key question that motivates the research is the investigation of the aforementioned Inductor–Diode and Inductor–Capacitor–Diode, current multiplier/divider cells, in a step-down application. The two-stage buck converter is used as a study case to achieve the output voltage required. To extend the intermediate voltage level flexibility in the two-stage buck converter, a second switch was implemented replacing a diode, which gives an extra degree-of-freedom for the topology. Based on this modification, three regions of operation are theoretically defined, depending on the operational duty cycles δ₂ and δ₁ of switches S₂ and S₁. The intermediate and output voltage levels are defined based on the choice of the region of operation and are mapped herein, summarizing the possible voltage levels achieved by each configuration. The paper presents the theoretical analysis, simulation, implementation and experimental validation of a converter with the following specifications; 48 V/12 V input-to-output voltage, different intermediate voltage levels, 100 W power rating, and switching frequency of 300 kHz. Comparisons between mathematical, simulation, and experimental results are made with the objective of validating the statements herein introduced. Full article

(This article belongs to the Special Issue Design and Control of Power Converters 2019)

► Show Figures

Figure 1

17 pages, 6480 KiB

Open AccessArticle

A New Adaptive Approach to Control Circulating and Output Current of Modular Multilevel Converter

by Muhammad Ishfaq, Waqar Uddin, Kamran Zeb, Imran Khan, Saif Ul Islam, Muhammad Adil Khan and Hee Je Kim

Energies 2019, 12(6), 1118; https://doi.org/10.3390/en12061118 - 22 Mar 2019

Cited by 19 | Viewed by 4352

Abstract

This paper addresses the output current and circulating current control of the modular multi-level converter (MMC). The challenging task of MMCs is the control of output current and circulating current. Existing control structures for output and circulating current achieve control objectives with comparatively [...] Read more.

This paper addresses the output current and circulating current control of the modular multi-level converter (MMC). The challenging task of MMCs is the control of output current and circulating current. Existing control structures for output and circulating current achieve control objectives with comparatively complex controllers and the designed parameters for the controller is also difficult. In this paper, an adaptive proportional integral (API) controller is designed to control the output current and the circulating current. The output current is regulated in

α β

axes while the circulating current is regulated in the

a b c

stationary frame to enhance MMC performance. The output and circulating current control results using an API controller are compared with the conventional proportional resonant (PR) controller in terms of transient response, stability, optimal performance, and reference tracking for results verification. The API control architecture significantly improve transient response, stability, and have excellent reference tracking capability. Moreover, it controls output current and converges the circulating current to a desired value. The control structure is designed for a three-phase MMC system, simulated and analyzed in MATLAB-Simulink. Full article

(This article belongs to the Special Issue Design and Control of Power Converters 2019)

► Show Figures

Figure 1

15 pages, 6886 KiB

Open AccessArticle

High-Efficiency Design and Control of Zeta Inverter for Single-Phase Grid-Connected Applications

by Woo-Young Choi and Min-Kwon Yang

Energies 2019, 12(6), 974; https://doi.org/10.3390/en12060974 - 13 Mar 2019

Cited by 5 | Viewed by 2664

Abstract

The conventional zeta inverter has been used for single-phase grid-connected applications. However, it has high switching losses to operate at high switching frequency in the continuous conduction mode (CCM). To address this drawback, this paper suggests a high-efficiency zeta inverter using active clamp [...] Read more.

The conventional zeta inverter has been used for single-phase grid-connected applications. However, it has high switching losses to operate at high switching frequency in the continuous conduction mode (CCM). To address this drawback, this paper suggests a high-efficiency zeta inverter using active clamp and synchronous rectification techniques. The proposed inverter utilizes the active clamp circuit for reducing switching losses. The non-complementary switching scheme is adopted for not only clamping the switch voltage stresses, but also alleviating the circulating energy. In addition, the synchronous rectification is implemented for reducing the body diode conduction of power switches. By using the silicon carbide (SiC) metal oxide semiconductor field effect transistors (MOSFETs), the switching performance of the proposed inverter is improved. Its operation principle and control strategy are presented. A 220-W prototype has been designed and tested to evaluate the performance of the proposed inverter. Full article

(This article belongs to the Special Issue Design and Control of Power Converters 2019)

► Show Figures

Figure 1

19 pages, 5494 KiB

Open AccessFeature PaperArticle

6.78-MHz, 50-W Wireless Power Supply Over a 60-cm Distance Using a GaN-Based Full-Bridge Inverter

by Seung-Hwan Lee, Kyung-Pyo Yi and Myung-Yong Kim

Energies 2019, 12(3), 371; https://doi.org/10.3390/en12030371 - 24 Jan 2019

Cited by 9 | Viewed by 12117

Abstract

An inductive wireless power transfer system is proposed as a power supply for an on-line monitoring system for an overhead catenary. Because of the high voltage (25 kV_rms) applied to the catenary, galvanic isolation was required to supply power to the [...] Read more.

An inductive wireless power transfer system is proposed as a power supply for an on-line monitoring system for an overhead catenary. Because of the high voltage (25 kV_rms) applied to the catenary, galvanic isolation was required to supply power to the attached monitoring system. The proposed wireless power system was able to transmit 50 W over a distance of 60 cm at 6.78 MHz. Design methodologies for the transmitter and the receiver coils, 6.78-MHz GaN-based full-bridge inverter, and rectifier are proposed in this paper. Pareto optimality, a multi-objective optimization technique, was used to determine optimal solutions in terms of efficiency and copper usage. A 100-W, 6.78-MHz full-bridge inverter was developed using 100 V, 35 A, E-HEMT GaN MOSFETs. Because of the high operating frequency, two factors were considered in the design of the full-bridge inverter, (1) close placement of the gate driver and the switch to minimize parasitic inductance and the resulting fluctuation of the drive signal and (2) effective heat dissipation from the switches and gate drivers for a high power rating. In addition, a full-wave rectifier was built using Schottky barrier diodes with a reverse recovery time of a few tens of nano-seconds. The developed wireless power system was experimentally evaluated. The measured coil-to-coil efficiency was 77%, and the measured efficiencies of the inverter and the rectifier were 92% and 93%, respectively. The overall system efficiency was 57% for a transfer of 47 W. Finally, the dependences of the efficiency on the distance, operating frequency, and load were evaluated. Full article

(This article belongs to the Special Issue Design and Control of Power Converters 2019)

► Show Figures

Figure 1

21 pages, 5446 KiB

Open AccessArticle

Direct Digital Design of PIDF Controllers with ComPlex Zeros for DC-DC Buck Converters

by Stefania Cuoghi, Lorenzo Ntogramatzidis, Fabrizio Padula and Gabriele Grandi

Energies 2019, 12(1), 36; https://doi.org/10.3390/en12010036 - 23 Dec 2018

Cited by 13 | Viewed by 4173

Abstract

This paper presents a new direct digital design method for discrete proportional integral derivative PID + filter (PIDF) controllers employed in DC-DC buck converters. The considered controller structure results in a proper transfer function which has the advantage of being directly implementable by [...] Read more.

This paper presents a new direct digital design method for discrete proportional integral derivative PID + filter (PIDF) controllers employed in DC-DC buck converters. The considered controller structure results in a proper transfer function which has the advantage of being directly implementable by a microcontroller algorithm. Secondly, it can be written as an Infinite Impulse Response (IIR) digital filter. Thirdly, the further degree of freedom introduced by the low pass filter of the transfer function can be used to satisfy additional specifications. A new design procedure is proposed, which consists of the conjunction of the pole-zero cancellation method with an analytical design control methodology based on inversion formulae. These two methods are employed to reduce the negative effects introduced by the complex poles in the transfer function of the buck converter while exactly satisfying steady-state specifications on the tracking error and frequency domain requirements on the phase margin and on the gain crossover frequency. The proposed approach allows the designer to assign a closed-loop bandwidth without constraints imposed by the resonance frequency of the buck converter. The response under step variation of the reference value, and the disturbance rejection capability of the proposed control technique under load variations are also evaluated in real-time implementation by using the Arduino DUE board, and compared with other methods. Full article

(This article belongs to the Special Issue Design and Control of Power Converters 2019)

► Show Figures

Figure 1

16 pages, 5401 KiB

Open AccessArticle

New DC Grid Power Line Communication Technology Used in Networked LED Driver

by Huipin Lin, Jin Hu, Xiao Zhou, Zhengyu Lu and Lujun Wang

Energies 2018, 11(12), 3531; https://doi.org/10.3390/en11123531 - 18 Dec 2018

Cited by 2 | Viewed by 4990

Abstract

In order to reduce the cost and improve the reliability, real-time performance, and installation convenience of remote-controlled light-emitting diode (LED) lighting systems, a networked LED driving technology based on the direct current (DC) grid power line carrier is proposed. In this system, an [...] Read more.

In order to reduce the cost and improve the reliability, real-time performance, and installation convenience of remote-controlled light-emitting diode (LED) lighting systems, a networked LED driving technology based on the direct current (DC) grid power line carrier is proposed. In this system, an alternating current (AC)/DC bus converter converts the mains into a DC bus with multiple distributed LED drive powers on the DC bus. The AC/DC bus converter receives the user’s control command and modulates it into the DC bus voltage. The DC bus waveform changes to a square wave containing the high and low changes of the address information and command information. The LED drive power of the corresponding address receives energy from the DC bus and demodulates the commands, such as turning the lights on and off, dimming, etc., and performs the action. In order to make the waveform of the AC/DC bus converter have better rising and falling edge, this paper adopts the half-bridge topology with variable modal control. In the modulation process, the circuit works in buck mode and boost mode. Distributed LED drivers have DC/DC circuits and very simple demodulation circuits that dissipate energy and information from the DC bus. Through experiments, the technology not only simplifies the use of communication technology in application, but also reduces the application difficulty. Full article

(This article belongs to the Special Issue Design and Control of Power Converters 2019)

► Show Figures

Figure 1

16 pages, 2568 KiB

Open AccessArticle

Comparison of Novel Approaches to the Predictive Control of a DC-DC Boost Converter, Based on Heuristics

by Robert Baždarić, Danjel Vončina and Igor Škrjanc

Energies 2018, 11(12), 3300; https://doi.org/10.3390/en11123300 - 26 Nov 2018

Cited by 5 | Viewed by 2985

Abstract

This paper introduces novel approaches to the predictive control of a DC-DC boost converter and a comparison of the controllers built that consider all of the current objectives and minimize the complexity of the online processing. The primary concern is given to the [...] Read more.

This paper introduces novel approaches to the predictive control of a DC-DC boost converter and a comparison of the controllers built that consider all of the current objectives and minimize the complexity of the online processing. The primary concern is given to the applicability of the inclined methods for systems that are physically small but considered physically fast processes. Although the performed methodologies are simulated and applied to a DC-DC boost converter, they can have broader applicability for different switched affine systems as a subgroup of the hybrid systems. The introduced methods present an alternative way of building the process model based on the fuzzy identification that contributes to the final objective: the applicability of the predictive methods for fast processes. Full article

(This article belongs to the Special Issue Design and Control of Power Converters 2019)

► Show Figures

Figure 1

21 pages, 3805 KiB

Open AccessFeature PaperArticle

Computer-Aided Design of Digital Compensators for DC/DC Power Converters

by Pablo Zumel, Cristina Fernández, Marlon A. Granda, Antonio Lázaro and Andrés Barrado

Energies 2018, 11(12), 3251; https://doi.org/10.3390/en11123251 - 22 Nov 2018

Cited by 9 | Viewed by 3663

Abstract

Digital control of high-frequency power converters has been used extensively in recent years, providing flexibility, enhancing integration, and allowing for smart control strategies. The core of standard digital control is the discrete linear compensator, which can be calculated in the frequency domain using [...] Read more.

Digital control of high-frequency power converters has been used extensively in recent years, providing flexibility, enhancing integration, and allowing for smart control strategies. The core of standard digital control is the discrete linear compensator, which can be calculated in the frequency domain using well-known methods based on the frequency response requirements (crossover frequency, f_c, and phase margin, PM). However, for a given compensator topology, it is not possible to fulfill all combinations of crossover frequency and phase margin, due to the frequency response of the controlled plant and the limitations of the compensator. This paper studies the performance space (f_c, PM) that includes the set of achievable crossover frequencies and phase margin requirements for a combination of converter topology, compensator topology, and sensors, taking into account the effects of digital implementation, such as delays and limit cycling. Regarding limit cycling, two different conditions have been considered, which are related to the design of the digital compensator: a limited compensator integral gain, and a minimum gain margin. This approach can be easily implemented by a computer to speed up the calculations. The performance space provides significant insight into the control design, and can be used to compare compensator designs, select the simplest compensator topology to achieve a given requirement, determine the dynamic limitations of a given configuration, and analyze the effects of delays in the performance of the control loop. Moreover, a figure of merit is proposed to compare the dynamic performance of the different designs. The main goal is to provide a tool that identifies the most suitable compensator design in terms of the dynamic performance, the complexity of the implementation, and the computational resources. The proposed procedure to design the compensator has been validated in the laboratory using an actual DC/DC converter and a digital hardware controller. The tests also validate the theoretical performance space and the most suitable compensator design for a given dynamic specification. Full article

(This article belongs to the Special Issue Design and Control of Power Converters 2019)

► Show Figures

Figure 1

14 pages, 5219 KiB

Open AccessArticle

Disturbance Rejection Control Method for Isolated Three-Port Converter with Virtual Damping

by Jiang You, Mengyan Liao, Hailong Chen, Negareh Ghasemi and Mahinda Vilathgamuwa

Energies 2018, 11(11), 3204; https://doi.org/10.3390/en11113204 - 18 Nov 2018

Cited by 2 | Viewed by 2780

Abstract

The high-power density and capability of three-port converters (TPCs) in generating demanded power synchronously using flexible control strategy make them potential candidates for renewable energy applications to enhance efficiency and power density. The control performance of isolated TPCs can be degraded due to [...] Read more.

The high-power density and capability of three-port converters (TPCs) in generating demanded power synchronously using flexible control strategy make them potential candidates for renewable energy applications to enhance efficiency and power density. The control performance of isolated TPCs can be degraded due to the coupling and interaction of power transmission among different ports, variations of model parameters caused by the changes of the operation point and resonant peak of LC circuit. To address these issues, a linear active disturbance rejection control (LADRC) system is developed in this paper for controlling the utilized TPC. A virtual damping based method is proposed to increase damping ratio of current control subsystem of TPC which is beneficial in further improving dynamic control performance. The simulation and experimental results show that compared to the traditional frequency control strategy, the control performance of isolated TPC can be improved by using the proposed method. Full article

(This article belongs to the Special Issue Design and Control of Power Converters 2019)

► Show Figures

Figure 1

18 pages, 8025 KiB

Open AccessArticle

Analysis and Control of Electrolytic Capacitor-Less LED Driver Based on Harmonic Injection Technique

by Mahmoud Nassary, Mohamed Orabi, Manuel Arias, Emad M. Ahmed and El-Sayed Hasaneen

Energies 2018, 11(11), 3030; https://doi.org/10.3390/en11113030 - 5 Nov 2018

Cited by 13 | Viewed by 3997

Abstract

AC-DC LED drivers may have a lifespan shorter than the lifespan of LED chips if electrolytic capacitors are used in their construction. Using film capacitors solves this problem but, as their capacitance is considerably lower, the low-frequency ripple will increase. Solving this problem [...] Read more.

AC-DC LED drivers may have a lifespan shorter than the lifespan of LED chips if electrolytic capacitors are used in their construction. Using film capacitors solves this problem but, as their capacitance is considerably lower, the low-frequency ripple will increase. Solving this problem by limiting the output ripple to safe values is possible by distorting the input current using harmonic injection technique, as long as these harmonics still complies with Power Factor Regulations (Energy Star). This harmonic injection alleviates the requirements imposed to the output capacitor in order to limit the low-frequency ripple in the output. This idea is based on the fact that LEDs can be driven by pulsating current with a limited Peak-To-Average Ratio (PTAR) without affecting their performance. By considering the accurate model of LEDs, instead of the typical equivalent resistance, this paper presents an improved and more reliable calculation of the intended harmonic injection. Wherein, its orders and values can be determined for each input/output voltage to obtain the specified PTAR and Power Factor (PF). Also, this harmonic injection can be simply implemented using a single feedback loop, its control circuit has features of wide bandwidth, simple, single-loop and lower cost. A 21W AC-DC buck converter is built to validate the proposed circuit and the derived mathematical model and it complies with IEC61000 3-2 class D standard. Full article

(This article belongs to the Special Issue Design and Control of Power Converters 2019)

► Show Figures

Figure 1

18 pages, 14119 KiB

Open AccessEditor’s ChoiceArticle

Power and Voltage Control for Single-Phase Cascaded H-Bridge Multilevel Converters under Unbalanced Loads

by Daliang Yang, Li Yin, Shengguang Xu and Ning Wu

Energies 2018, 11(9), 2435; https://doi.org/10.3390/en11092435 - 14 Sep 2018

Cited by 15 | Viewed by 3670

Abstract

The conventional control method for a single-phase cascaded H-bridge (CHB) multilevel converter is vector (dq) control; however, dq control requires complicated calculations and additional time delays. This paper presents a novel power control strategy for the CHB multilevel converter. A power-based [...] Read more.

The conventional control method for a single-phase cascaded H-bridge (CHB) multilevel converter is vector (dq) control; however, dq control requires complicated calculations and additional time delays. This paper presents a novel power control strategy for the CHB multilevel converter. A power-based dc-link voltage balance control is also proposed for unbalanced load conditions. The new control method is designed in a virtual αβ stationary reference frame without coordinate transformation or phase-locked loop (PLL) to avoid the potential issues related to computational complexity. Because only imaginary voltage construction is needed in the proposed control method, the time delay from conventional imaginary current construction can be eliminated. The proposed method can obtain a sinusoidal grid current waveform with unity power factor. Compared with the conventional dq control method, the power control strategy possesses the advantage of a fast dynamic response. The stability of the closed-loop system with the dc-link voltage balance controller is evaluated. Simulation and experimental results are presented to verify the accuracy of the proposed power and voltage control method. Full article

(This article belongs to the Special Issue Design and Control of Power Converters 2019)

► Show Figures

Figure 1

22 pages, 2009 KiB

Open AccessArticle

Analysis, Modeling, and Control of Half-Bridge Current-Source Converter for Energy Management of Supercapacitor Modules in Traction Applications

by Jorge Garcia, Pablo Garcia, Fabio Giulii Capponi and Giulio De Donato

Energies 2018, 11(9), 2239; https://doi.org/10.3390/en11092239 - 26 Aug 2018

Cited by 13 | Viewed by 4809

Abstract

In this work, an in-depth investigation was performed on the properties of the half-bridge current-source (HBCS) bidirectional direct current (DC)-to-DC converter, used to interface two DC-link voltage sources with a high-voltage-rating mismatch. The intended implementation is particularly suitable for the interfacing of a [...] Read more.

In this work, an in-depth investigation was performed on the properties of the half-bridge current-source (HBCS) bidirectional direct current (DC)-to-DC converter, used to interface two DC-link voltage sources with a high-voltage-rating mismatch. The intended implementation is particularly suitable for the interfacing of a supercapacitor (SC) module and a battery stack in a hybrid storage system (HSS) for automotive applications. It is demonstrated that the use of a synchronous rectification (SR) modulation scheme benefits both the power-stage performance (in terms of efficiency and reliability) and the control-stage performance (in terms of simplicity and versatility). Furthermore, an average model of the converter, valid for every operating condition, is derived and utilized as a tool for the design of the control system. This model includes the effects of parasitic elements (mainly the leakage inductance of the transformer) and of the converter snubbers. A 3 kW prototype of the converter was used for experimental validation of the converter modeling, design, and performance. Finally, a discussion on the control strategy of the converter operation is included. Full article

(This article belongs to the Special Issue Design and Control of Power Converters 2019)

► Show Figures

Graphical abstract

16 pages, 5802 KiB

Open AccessArticle

MPPT and SPPT Control for PV-Connected Inverters Using Digital Adaptive Hysteresis Current Control

by Triet Nguyen-Van, Rikiya Abe and Kenji Tanaka

Energies 2018, 11(8), 2075; https://doi.org/10.3390/en11082075 - 9 Aug 2018

Cited by 11 | Viewed by 4006

Abstract

Most PV systems are usually controlled by a Maximum Power Point Tracking (MPPT) algorithm to maximize the generated electrical power. However, the maximum power is often unstable and depends on the solar irradiance and temperature. This makes it difficult to control the power [...] Read more.

Most PV systems are usually controlled by a Maximum Power Point Tracking (MPPT) algorithm to maximize the generated electrical power. However, the maximum power is often unstable and depends on the solar irradiance and temperature. This makes it difficult to control the power grid supply-demand balance due to fluctuations caused by the increase of renewable and variable PV systems. This paper proposes a new control algorithm for a PV-connected inverter called Specified Power Point Tracking (SPPT) control in addition to the conventional Maximum Power Point Tracking (MPPT) control. The PV system is controlled to generate the maximum power or a specified power depending on the electricity transactions comes from the electricity trading system. A high-speed FPGA-based digital adaptive hysteresis current control method, which has fast and stable response and simple structure comparing with the popular Sine-triangle Pulse Width Modulation (SPWM) method, is proposed to implement the MPPT and SPPT control. The adaptive hysteresis current band is calculated adaptively to improve a disadvantage of the classical fixed band hysteresis current control on the varying switching frequency. A reference current used in the adaptive hysteresis current control is calculated such that the output power of the PV-connected inverter is maximized in the MPPT control or is maintained at a given value in the SPPT control. The experimental and simulation results show that the PV-connected inverter under the proposed control algorithm generates the desired power almost exactly and yields stable and fast response despite the varying irradiance. Full article

(This article belongs to the Special Issue Design and Control of Power Converters 2019)

► Show Figures

Figure 1

20 pages, 2316 KiB

Open AccessArticle

Design of Current Programmed Switching Converters Using Sliding-Mode Control Theory

by Javier Calvente, Abdelali El Aroudi, Roberto Giral, Angel Cid-Pastor, Enric Vidal-Idiarte and Luis Martínez-Salamero

Energies 2018, 11(8), 2034; https://doi.org/10.3390/en11082034 - 6 Aug 2018

Cited by 6 | Viewed by 4002

Abstract

This paper presents a comprehensive approach to analyze and design the voltage and current loops of switching DC-DC converters by using sliding-mode control theory. The approach is interchangeably applied to switching converters under current-programmed control with both fixed and variable frequency modulation. An [...] Read more.

This paper presents a comprehensive approach to analyze and design the voltage and current loops of switching DC-DC converters by using sliding-mode control theory. The approach is interchangeably applied to switching converters under current-programmed control with both fixed and variable frequency modulation. An ideal sliding-mode dynamics model is then obtained together with its circuit schematic representation that can be used for designing the output voltage compensator, as well as to predict the large signal behavior such as during start-up and under large disturbances. Simulations and experimental measurements illustrate the theoretical approach for two different examples of switching converters. Full article

(This article belongs to the Special Issue Design and Control of Power Converters 2019)

► Show Figures

Figure 1

21 pages, 8629 KiB

Open AccessArticle

Suppression Research Regarding Low-Frequency Oscillation in the Vehicle-Grid Coupling System Using Model-Based Predictive Current Control

by Yaqi Wang and Zhigang Liu

Energies 2018, 11(7), 1803; https://doi.org/10.3390/en11071803 - 10 Jul 2018

Cited by 7 | Viewed by 3157

Abstract

Recently, low-frequency oscillation (LFO) has occurred many times in high-speed railways and has led to traction blockades. Some of the literature has found that the stability of the vehicle-grid coupling system could be improved by optimizing the control strategy of the traction line-side [...] Read more.

Recently, low-frequency oscillation (LFO) has occurred many times in high-speed railways and has led to traction blockades. Some of the literature has found that the stability of the vehicle-grid coupling system could be improved by optimizing the control strategy of the traction line-side converter (LSC) to some extent. In this paper, a model-based predictive current control (MBPCC) approach based on continuous control set in the dq reference frame for the traction LSC for electric multiple units (EMUs) is proposed. First, the mathematical predictive model of one traction LSC is deduced by discretizing the state equation on the alternating current (AC) side. Then, the optimal control variables are calculated by solving the performance function, which involves the difference between the predicted and reference value of the current, as well as the variations of the control voltage. Finally, combined with bipolar sinusoidal pulse width modulation (SPWM), the whole control algorithm based on MBPCC is formed. The simulation models of EMUs’ dual traction LSCs are built in MATLAB/SIMULINK to verify the superior dynamic and static performance, by comparing them with traditional transient direct current control (TDCC). A whole dSPACE semi-physical platform is established to demonstrate the feasibility and effectiveness of MBPCC in real applications. In addition, the simulations of multi-EMUs accessed in the vehicle-grid coupling system are carried out to verify the suppressing effect on LFO. Finally, to find the impact of external parameters (the equivalent leakage inductance of vehicle transformer, the distance to the power supply, and load resistance) on MBPCC’s performance, the sensitivity analysis of these parameters is performed. Results indicate that these three parameters have a tiny impact on the proposed method but a significant influence on the performance of TDCC. Both oscillation pattern and oscillation peak under TDCC can be easily influenced when these parameters change. Full article

(This article belongs to the Special Issue Design and Control of Power Converters 2019)

► Show Figures

Figure 1

Review

Jump to: Research

18 pages, 8965 KiB

Open AccessReview

Challenges and Design Requirements for Industrial Applications of AC/AC Power Converters without DC-Link

by Pawel Szczesniak

Energies 2019, 12(8), 1581; https://doi.org/10.3390/en12081581 - 25 Apr 2019

Cited by 14 | Viewed by 6099

Abstract

AC/AC converters that do not have a DC energy storage element, such as a matrix chopper and a matrix converter, are increasingly becoming alternatives to conventional two-stage AC/DC/AC converters and thyristor choppers. In such systems, the main DC-link capacitor does not exist, so [...] Read more.

AC/AC converters that do not have a DC energy storage element, such as a matrix chopper and a matrix converter, are increasingly becoming alternatives to conventional two-stage AC/DC/AC converters and thyristor choppers. In such systems, the main DC-link capacitor does not exist, so the system provides more reliable operation and makes it possible to reduce the financial costs of its construction. It should be noted that AC/AC converters without an energy storage element in a form of DC-link capacitors have not been implemented on an industrial scale. The reasons involve technical aspects and cost components. The main aim of this paper is to present some of the challenges and selected design requirements for industrial applications of AC/AC high reliability power converters. Full article

(This article belongs to the Special Issue Design and Control of Power Converters 2019)

► Show Figures

Figure 1

Journal Menu

Journal Browser

Design and Control of Power Converters 2019

Share This Special Issue

Special Issue Editor

Special Issue Information

Keywords

Benefits of Publishing in a Special Issue

Published Papers (21 papers)

Research

Review

Further Information

Guidelines

MDPI Initiatives

Follow MDPI