Phase-shift Control Strategy Research Articles

An Interleaved Battery Charger Circuit for a Switched Capacitor Inverter-Based Standalone Single-Phase Photovoltaic Energy Management System

A single-phase bidirectional DC/DC battery charger with a P&O MPPT current control strategy for a standalone energy management system has been integrated with an interleaved switched capacitor DC/AC inverter with an RMS feedback phase-shifted unipolar sinusoidal PWM control strategy. In the published literature, P&O MPPT control is used to drive a boost converter connected in parallel to a battery charger; this modified strategy combines a P&O MPPT algorithm with current control to drive an interleaving buck-boost battery charger. This battery charger circuit is connected in parallel to a closed loop controlled interleaved inverter that feeds the AC home load. MATLAB/Simulink based simulation circuit was developed and used to validate the successful integration of the interleaved battery charger with the global system. To do this, the system is tested with varying input conditions of irradiance and temperature. The system’s response to these variable inputs is monitored and analysed. The simulation results show the proposed method is effective for standalone battery-based PV systems. The system provides a more efficient and faster response compared with both an interleaved and non-interleaved voltage-controlled battery charger circuit that is also integrated with the global system. This battery charger control strategy is also shown to protect the battery from over-charging as well as discharging below 25%, which can improve and protect the long-term battery performance. Compared with novel industry approaches, the proposed system is simpler by nature due to the reduced number of conversions and therefore a reduced number of components which provides economic advantages.

Simulation optimal and design of 3-kW DC-DC converter for pure electric vehicles

There are significant differences between pure electric vehicles and traditional fuel vehicles. High-power converters are required to meet the increased energy consumption requirements of loads within pure electric vehicles. A high-power integrated DC-DC converter is designed to meet the requirements of pure electric vehicles. First, the characteristics of LLC resonant converters are analyzed, and a fuzzy adaptive PID frequency conversion phase-shift soft switching control strategy is proposed. Second, the fuzzy controller is designed based on the MATLAB toolbox based on the characteristics of electric vehicle converters. Then, in order to further improve the efficiency of the converter, a planar transformer is proposed and optimized. It is found that with the increase in the switching frequency, the loss is smaller, which is more conducive to improving the efficiency. Simulation results show that zero-voltage switching and zero-current switching can be realized by using the proposed control strategy, and experimental results show that the proposed strategy is significantly more efficient under non-heavy-load conditions. The minimum and maximum efficiency values are 92% and 97.38%, respectively. The high-power converter ensures the normal operation of the load of pure electric vehicles. This work provides a method for developing high-power DC-DC converters and improving efficiency.

Resonant DC/DC Converters: Investigating Phase-Shift Control

The paper presents an innovative approach to control the voltage of an LCL-T type converter at the output side against variation at input and load ports, utilizing a fixed-frequency phase-shift control scheme. The examination of the converter is performed employing a Fourier series method that takes into account the effect of n-harmonics. To assure high-frequency switches with a zero-voltage switching (ZVS) technique, the lagging pf mode is utilized. PSIM simulations were used to investigate the performance of a 300 W converter. With the minimal input voltage, all switches turn on with ZVS for all loading conditions, whereas the ZVS strategy loses by two switches when the voltage at the input is highest. The power loss calculations of each component are performed and presented in a pie chart. The findings of the experiments are presented and verified with theoretical and simulation results. It is demonstrated that for both input voltage and load fluctuations, a minor adjustment in pulse width is sufficient to keep the output voltage constant.

A Phase-Shifting DC-Link Voltage Control Strategy for Parallel Inverters to Suppress Interharmonics in PV Systems

The large-scale installation of PV systems leads to interharmonic problems, which greatly affect the power quality of power system. It has been revealed that the DC-link voltage oscillation caused by the perturbation maximum power point tracking (MPPT) algorithm is one of the main causes of interharmonics. To address this issue, a phase-shifting DC-link voltage control strategy for parallel inverters to suppress interharmonics in PV systems is proposed. In this method, the relationship between interharmonic characteristics and reference DC-link voltage is the basis for suppressing interharmonics. The proposed system contains two parallel inverters whose reference DC-link voltages are antiphase. Therefore, the interharmonic current can be eliminated with each other. Simulations and experiments have been constructed to verify the effectiveness of the proposed interharmonic suppression strategy.

Half-Bridge Lithium-Ion Battery Equalizer Based on Phase-Shift Strategy

The energy flow is step-by-step among Lithium-ion-battery when an equalizer based on the buck-boost converter is adopted, resulting in a long energy transmission path and low equalization efficiency. First, a Lithium-ion-battery equalizer based on the dual active half-bridge is studied in this paper. Second, the key parameters of the energy flow between cells in the same group and cells in different groups in the equalizer are analyzed. Third, a phase shift control strategy is put forward according to the analysis results. The equalizer with the proposed control strategy not only can realize the energy flow between cells in the same group and different groups but also work at high frequency. Therefore, the transformer can be designed to be small in size and light in weight, greatly reducing the volume and weight of the equalizer. A prototype of the dual active half-bridge equalizer with four lithium batteries was managed. The experimental results show that the proposed Lithium-ion-battery equalizer based on phase shift control has good equalization performances.

Phase-Duty Modulated Loop Decoupling and Design Optimization for a Triple Active Bridge Converter for Light Electric Vehicle Charging

This article presents a comprehensive generalized harmonics approximation based modeling and design of a triple active bridge (TAB) dc–dc converter topology aimed to facilitate simultaneous—main and auxiliary—battery charging solutions for light electric vehicle charging applications. A three-loop control scheme, incorporating the duty and phase control parameters, is proposed in this article to address the issue of inherent coupling of two output bridges and their control loops (as observed in conventional phase modulation-based voltage control techniques), along with an objective to enhance the operational efficiency of the system, in affiliation with a real-time power flow optimization algorithm. Adhering to the objective of achieving minimized losses, the optimization algorithm provides insightful design limitations in terms of selecting the required leakage inductances to ensure desired power flow at the output bridges. Furthermore, to validate the effectiveness of the proposed three-loop control, a detailed set of simulation and experimental results are presented at various steady state and dynamic load change conditions. A detailed analytical loss model of the TAB topology is also presented along with a comparative study elucidating the effectiveness of the proposed three-loop control over the conventional control schemes. The analyses portray a peak efficiency of 96.24% at the rated load of 300 W, which is 2.94% and 4.97% higher than the decoupled and the conventional phase shift control schemes, respectively.

Simulations to Eliminate Backflow Power in an Isolated Three-Port Bidirectional DC–DC Converter

The aim of this work was to eliminate the backflow power present in an isolated three-port DC–DC converter. Backflow power (which is an inherent property of phase-shifted DC–DC converters) is the major contributor of circulating current the converter, which in turn is known to be the leading cause of system loss. The dual phase shift (DPS) control scheme (which alters the transformer voltage waveform at the different winding terminals) was used to reduce the backflow power. Mathematical relations for the backflow power present in the three-port converter were derived. And from this equation, an operating point in which the backflow power is zero was also obtained. This condition for zero backflow power was confirmed by simulations on PSIM. Added to this were simulation results that show other operating conditions in which zero backflow power could be obtained in the converter. In addition, equations for the power processed at the different ports of the converter were also presented, and 3D plots were made to illustrate the variation of the power and backflow power with respect to the phase shift ratios of the DPS control scheme. It was observed that the backflow power can be totally removed from the three-port converter when using this control scheme.

A PWM Plus Phase-Shift Control for Four-Switch Buck-Boost Converter to Achieve ZVS in Full Input Voltage and Load Range

Four-switch buck-boost (FSBB) converter features positive output voltage and low voltage stress of power switches. In this article, a pulsewidth modulation plus phase-shift control scheme is proposed to achieve zero-voltage-switching for all the power switches in full input voltage and load range and minimize the inductor current ripple and root mean square (RMS) value. The implementation of the proposed control scheme is given. A prototype of a 500-W FSBB converter is built and tested in the lab, and the experimental results verify the effectiveness of the proposed control scheme.

An Asymmetrical Phase-Shift Scheme of Three-Phase Dual Active Bridge With Minimum Current Root-Mean-Square Value Control

The three-phase dual active bridge (3ph-DAB) converter is a promising topology attracting increasing attention. However, because it is limited to symmetrical three-phase bridge control, the conventional single-phase-shift control method (SPS) remains the most common method for 3ph-DAB converter. The obvious shortcomings of SPS control include the soft-switching failure, massive circulating energy, and high root-mean-square (rms) current value at the light load, particularly with large voltage variation-ratio conditions. To overcome these drawbacks, this article proposes a novel asymmetrical phase shift (APS) control strategy. Unlike other optimized modulation schemes, this optimized strategy breaks the symmetrical control rules of three-phase bridges by introducing variable phase-shift angles among three-phase legs. The novel APS control strategy can substantially reduce the current's rms value and extend the soft-switching operation range due to these additional phase-shift angles. Further, the analytical solutions for the optimal phase-shift angles are derived by solving the global optimal condition equations. Analytical solutions, compared with complex numerical solutions derived by other optimized schemes, can be easily adopted in digital implementation and perform well under changing parameter conditions. Finally, experimental results verify the outstanding performance of the proposed modulation strategy.

Research on Wide Input Voltage LLC Resonant Converter and Compound Control Strategy

This paper presents a wide input voltage vehicle DC/DC converter based on an LLC resonant converter for a 48 V light hybrid power system. According to the design requirements of on-board DC/DC converters and an analysis of their system characteristics, a full-bridge LLC resonant converter is employed with a zero-voltage activation of the switching transistors through resonant elements. In terms of the control strategy, the unsatisfactory high-frequency regulation gain of an LLC resonant converter is analyzed under the frequency modulation (FM) control strategy. In addition, to accommodate wide input voltage operating conditions, a composite control strategy is proposed by combining the advantages of the frequency modulation control strategy and phase shift control strategy, analyzing their control principles, and discussing the selection of the control mode switching point. By modeling LLC resonant converters with simulation software, the obtained results verify the effectiveness of the composite control strategy for LLC resonant converters. An experimental platform based on the TMS320F28335 controller, which can achieve stable operation with an input voltage in the range of 300 V–600 V and an output voltage of 48 V, is then built. The experimental results verify the feasibility of the design.

Single-Stage Multi-Input Buck Type High-Frequency Link's Inverters With Multiwinding and Time-Sharing Power Supply

A circuit structure, topological family, and unipolar phase-shift SPWM master-slave power distribution energy management control strategy (EMCS) of the single-stage Buck type multi-input high-frequency (HF) link's inverters with multiwinding time-sharing power supply are proposed in this article, in order to reduce the power conversion stage, volume and weight, and increase conversion efficiency and reliability. The key technologies of this kind of inverter, such as circuit structure and topological family, EMCS, power supply mode (PSM), and steady-state principle characteristics, are deeply studied. The circuit structure is composed of multiple isolated HF inverting bridges, a HF transformer with multi-input single-output, a cycloconverter and an output <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">LC</i> filter. The EMCS is to generate the bipolar tristate multilevel SPWM waves by phase-shift between the right arm and the left arm of multiple HF inverting bridges; the cycloconverter demodulates it into the unipolar tristate multilevel SPWM wave, and performs zero voltage commutation. The experimental results of the designed and developed 1kVA multi-input inverter prototype have shown it has the advantages of single-stage power conversion, HF electrical isolation, high conversion efficiency, small volume and weight, high reliability, stable output voltage, multi-input source master-slave power distribution, and smooth switching of different PSMs.

Design and optimization of a modular wireless power system based on multiple transmitters and multiple receivers architecture

Wireless Power Transfer (WPT) technology has been applied to electric vehicles (EVs), for its convenience, safety, and high reliability. However, for the traditional single-transmitter-single-receiver WPT system, due to its uneven electromagnetic field distribution, the power transfer capability and the anti-offset performance are always insufficient. The multi-transmitter-multi-receiver (MTMR) WPT system based on modular inverters with coils can not only improve the transmission power of the system but also boost the system’s anti-offset ability due to its more uniform magnetic field distribution. In this study, the topology and transmission characteristics of the MTMR WPT system are discussed accordingly: 1) A decoupling method of transmitting coil based on capacitance compensation is proposed, and the particle swarm optimization algorithm is used to derive the optimal design scheme of magnetic coupling coil. 2) A phase-shifting control strategy is proposed to realize the phase synchronization and current sharing control of coil current at each transmitter. Finally, the simulation and experimental results show that the modular wireless power transfer system with multiple transmitters and multiple receivers has strong power transmission capability and anti-offset performance.

Phase Shift-Controlled Dual-Frequency Multi-Load Converter with Independent Power Control for Induction Cooking Applications

Induction heating (IH) applications, assisted with converter topology and their control, have become very attractive in recent years. Independent power control for any induction cooking application with simple converter topology, multi-load handling capacity, and a control technique is still a research hot spot. This paper focuses on developing the dual-frequency converter for delivering power to two loads independently. The switching frequencies of the converter for loads 1 and 2 are selected as 20 and 80 kHz, respectively, and the inverter is operated by multiplexing two switching frequencies. The independent power control is performed using a phase shift control scheme and validated in real-time using a PIC16F877A microcontroller. The prototype of 1 kW is developed and load 1 is operated with 550 W and load 2 is operated with 270 W output power. The independent power control is verified for various values of the control angle (ϕ) and it is noticed that the efficiency is 91% at 0∘ and it is above 80% for other values of ϕ. The thermal model of the proposed system is studied using COMSOL multiphysics software and the experimental image is recorded using a FLIR thermal imager. It is noted that the temperature rise in the load is 78 ∘C and 38.5 ∘C for loads 1 and 2, respectively, at time t = 180 s.

Soft-Switching Bidirectional Switched-Capacitor DC–DC Converter With Multiple Phase Shift Control Methods

In this article, a bidirectional bridge modular switched-capacitor (BBMSC) dc–dc converter is proposed with soft switching and multiple phase shift control methods, including in-bridge single phase shift (ISPS) control, out-of-bridge single phase shift (OSPS) control, and dual phase shift (DPS) control method. The topology, phase shift control scheme, and operating states are analyzed. Then the circuit characteristics, such as output power and current stress characteristics, are given to analyze and compare the advantages of different phase shift control methods. In addition, the efficiency characteristics of various phase shift control methods are compared and analyzed from the perspective of magnitude of reverse power. A 300-W experimental prototype is constructed to verify the working principle and efficiency characteristic. The comparison of different phase shift control methods is validated by experimental results.

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 Modified Phase Shift Control of the Dual Active Bridge-Based Modular Power Electronic Transformer to Minimize the LVdc Side Voltage Ripples Under Unbalanced Load Conditions

Power Electronic Transformers (PETs) are considered as an emerging solution for power conversion due to their benefits over the low frequency power transformers (LFPTs) such as lower size, multi-port structure and different control functionalities. However, unbalanced load conditions may limit the reduction of size due to using bulky capacitors to absorb the resulting 2^nd harmonic voltage oscillations. This paper aims to provide a solution to this problem in the Dual Active Bridge (DAB)-based Modular Multilevel Converter Power Electronic Transformers (MMC-PET). In this study, a modified phase shift control strategy for the DAB isolation stage is presented. In this strategy, the duty cycle is allowed to change sinusoidally around the operating point. This consequently transfers the power oscillations to the HV side where their effect is less significant. The system is simulated using Matlab-Simulink under different unbalanced load conditions. Besides, the theoretical analysis and the simulation results are experimentally validated using a laboratory prototype. According to the obtained results, the proposed controller succeeded to reduce the voltage ripples from 7.5% to 0.2% and this helps in replacing large Aluminum electrolytic capacitors with low size film capacitors and consequently reducing the system overall size and volume which is a great benefit.

A Single-Stage Isolated AC–DC Converter Based on the Impedance Control Network Architecture

This article introduces a new single-stage universal-input isolated ac-dc converter based on the impedance control network (ICN) architecture. This resonant converter performs both power factor correction and output voltage regulation while operating at a constant switching frequency and duty ratio, by modulating the phase-shift between its two half-bridge inverters and the phase-shift between the two legs of its full-bridge rectifier. This phase-shift control strategy along with the ICN architecture also enables the converter to achieve high efficiency by ensuring zero-voltage-switching and near-zero-current-switching of all its inverter transistors throughout the line cycle and across wide ranges of input line voltage and output power. Power density is enhanced by realizing the three ICN inductors using a single magnetic structure with two coupled windings. This coupled inductor and a transformer constitute the two magnetic components of the proposed converter. A systematic methodology to design this ICN ac-dc converter is also introduced. A universal-input (90-265 V <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">rms</sub> ), 20-V output, 330-W, 400-kHz ICN ac-dc converter prototype is built and tested. This prototype achieves a power density of 37.9 W/in <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sup> and peak efficiencies of 91.7%, 92.2%, 93.2%, and 93.4% at 90, 120, 230, and 265 V <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">rms</sub> input, respectively.

Phase-Shifted TAB Converter System for Electric VTOL Aircraft

This paper investigates a triple-active-bridge converter for an all-electric VTOL(Vertical Take Off&Landing) aircraft, based on the Dual-active-bridge converter, presenting four working scenarios which matching the operating of e-VTOL. The converter adopts a phase-shifting control strategy and decouples the control network. Different targeted settings of the converter system are made for the various operating states of the e-VTOL, and the operating states of the TAB converter in different modes are simulated in MATLAB. The experimental results show that the TAB converter has more diverse operating modes, which can match future e-VTOL use in urban applications.

Research on Synchronous Phase Shift Control Strategy of Bilateral Converter in Bidirectional Inductive Power Transfer System

Research on Synchronous Phase Shift Control Strategy of Bilateral Converter in Bidirectional Inductive Power Transfer System

A Double-Pulse Energy Injection Converter With Reduced Switching Frequency for MHz WPT System

Class-E inverter is widely used in the wireless power transmission (WPT) system due to its high efficiency. Generally, its switching frequency should be in accordance with the resonant frequency. In a weak-coupling case, the maintenance of high transmission efficiency requires a higher resonant frequency, which would restrict its application due to the corresponding high switching frequency. To solve the issue, this article proposes a Class-E-based inverter with the phase shift control strategy, which enables the operation frequency of the inverter much lower than the resonant frequency. Besides, the transmitting coil accepts power injection twice during each period, which greatly enhances emission intensity. In addition, the proposed phase shift control strategy avoids the weakness of an extremely low duty cycle. Hence, it contributes to the MHz middle power WPT system. Then, simulations and experiments are implemented to verify that the WPT system with the proposed inverter maintains a high efficiency within the middle range and realizes nearly 50% transmission efficiency even in a very weak-coupling coefficient ( k=0.08). Finally, it is proved that the proposed converter and its control strategy are available.