Triple Phase Shift Research Articles

Triple Phase Shift Modulation Scheme for Bidirectional Wireless Power Transfer Systems With Efficiency Maximization

Triple Phase Shift Modulation Scheme for Bidirectional Wireless Power Transfer Systems With Efficiency Maximization

Research on the Isolated Three‐Port DC‐DC Converter with Resonant Parameter Compensation Capability and Its Performance Optimization

AbstractIn order to eliminate the adverse effects caused by power coupling of the isolated three‐port converter (ITPC), this paper proposes a three‐port resonant converter that uses a switch‐controlled‐capacitor (SCC) and an auxiliary inductor, which has resonant parameter compensation capability (RPC‐ITPC). The topology and operational principle of RPC‐ITPC are discussed in detail. To achieve resonant‐type power decoupling, it is usually necessary to ensure that the resonant frequency of the decoupling port resonant tank is consistent with the switching frequency, which puts high demands on the accuracy of the resonant components. To address the sensitivity of resonant‐type power decoupling to the parameters of resonant components, an SCC was adopted to solve the problem. The use of SCC enables the RPC‐ITPC to have resonant parameter compensation capability. In order to further optimize the performance of the RPC‐ITPC, a triple‐phase‐shift (TPS) modulation strategy is proposed to achieve the minimum RMS value of resonant current (MRMS‐TPSMS). Under the MRMS‐TPSMS, the switching devices of the power decoupling port have difficulty achieving ZVS turn‐on. To circumvent this problem, we realize ZVS of the decoupling port switching devices via auxiliary inductor current injection. Finally, a 1 kW experimental prototype was constructed to validate the theoretical propositions presented in this study. © 2024 Institute of Electrical Engineers of Japan and Wiley Periodicals LLC.

Performance Analysis of Electric Vehicle Fast Charging System with Dual Active Bridge Converter using Triple Phase Shift Modulation

Performance Analysis of Electric Vehicle Fast Charging System with Dual Active Bridge Converter using Triple Phase Shift Modulation

Overview of Isolated Bidirectional DC–DC Converter Topology and Switching Strategies for Electric Vehicle Applications

Isolated bidirectional DC–DC converters are becoming increasingly important in various applications, particularly in the electric vehicle sector, due to their ability to achieve bidirectional power flow and their safety features. This paper aims to review the switch strategies and topologies of isolated bidirectional DC–DC converters, with a specific focus on their applications in the field of electric vehicles. From the perspective of topology, PWM-type isolated bidirectional DC–DC converters, dual active bridge converters, and resonant-type isolated bidirectional DC–DC converters constitute the three main categories of these converters. The paper further examines the traditional switch strategies of these converters and discusses how specific switch technologies, such as single-phase shift, expanding-phase shift, double-phase shift, and triple-phase shift, can enhance the overall performance of isolated bidirectional DC–DC converters. The paper meticulously examines the characteristics of each topology and control scheme, as well as their typical use cases in practical applications. Particularly, the paper delves into the applications of isolated bidirectional DC–DC converters in the electric vehicle sector and draws conclusions regarding their potential and trends in future electric vehicle technology.

Second‐harmonic current reduction of dual active bridge with triple‐phase shift in two‐stage single‐phase inverter system

AbstractThis article proposes a method to effectively suppress second‐harmonic current (SHC) of dual active bridge (DAB) converter, which adopts the triple‐phase shift (TPS) modulation strategy, in two‐stage single‐phase inverter system. Load current feedforward control with twice the output voltage frequency notch filter inserted is introduced to ensure the dynamic response performance. The averaged model of the system is established to analyse the influence of output impedance of front‐end DAB converter on SHC from the perspective of impedance. The proposed method does not need to consider the accuracy of the intermediate bus capacitance. Finally, an experimental prototype was established to verify the correctness and effectiveness of the proposed SHC reduction method.

Circulating power flow restricted operation of the isolated bi-directional dual-active bridge DC-DC converter for battery charging applications

This paper presents the Non-Circulating Power Flow (NCPF) enabled Dual Active Bridge (DAB) converter controller strategy. The proposed DAB controller eliminates the non-circulating power flow for all the four conventional modulation algorithms, i.e., Single Phase Shift (SPS), Extended Phase Shift (EPS), Dual Phase Shift (DPS) and Triple Phase Shift (TPS) modulation schemes. This leads to lesser current stress and power loss across the DAB converter switches due to reduced peak inverse current. The proposed controller strategy finds various applications, such as in a Solid-State Transformer (SST) enabled microgrid, or for Electric Vehicle (EV) Energy Storage Unit (ESU: battery, supercapacitor) integrations, etc. The proposed NCPF operation reduces battery (and supercapacitor) current stress by upto 71.8 %, and improves operative environment, thus fostering its health and lifecycle. In NCPF mode, if the rating of installed switches (current and voltage ratings) remains unchanged, its power transfer capability is marginally reduced by mere 10.0 %. In addition to this, the operating range (i.e., controlling range of phase shift (Φ) and modulation index (m)) remains unaffected. This paper summarizes the DAB NCPF operation in restricted power flow mode as a function of Φ and m through 3-D and 4-D graphs. Finally, working of NCPF DAB is tested via both simulation and hardware platforms. Comparative results are shown for conventional and proposed modulation schemes on hardware platform, to showcase the elimination of circulating current in both forward and reverse DAB operating modes. It is inferred that proposed controller is worthy of real-world implementations.

Topology and Control Optimization of Bidirectional DC/DC Converter for Electric Vehicles

With the rapid development of intelligent electric vehicles, the number of electrical equipment increases, and the interconnection and energy transmission between on-board DC buses has become urgent. This paper proposes a partial isolated bidirectional converter based on dual active bridge converter. By partial switch sharing, the converter has a simplified structure and can supply energy to DC loads of different voltage levels. The system adopts a hybrid control strategy of pulse width modulation and triple phase shift modulation, and introduces a fundamental phase shift to reduce coupling between variables. The operation process is analyzed, and the models of transmitted power, current stress and soft-switching range under two typical operation modes, corresponding to the full load and light load, are established respectively. Under wide gain and different power distribution conditions, the multi-objective optimization is realized. Finally, the correctness of theoretical analysis is verified by experiments.

High Efficiency Dual-Active-Bridge Converter with Triple-Phase-Shift Control for Battery Charger of Electric Vehicles

An optimal modulation scheme with triple-phase-shift (TPS) control could increase the efficiency in the entire load range for a dual-active-bridge (DAB) converter under wide output voltage range conditions. Therefore, this study proposes a convergent approach to TPS mode selection, coupled with an optimal modulation scheme, ensuring the circuit’s efficiency over the entire range in the realm of a high-power and high-efficiency battery charger for electric vehicles. The convergent approach to TPS mode selection also reduces the numerous cases for small-signal analysis through general average modeling. After verifying the small-signal models under various voltage transfer ratios and load conditions to verify the stability, a converter prototype with a rated power of 15 kW is built and tested. Thus, a peak efficiency of 97.7% can be achieved.

A Triple Phase Shift Control Method for Bidirectional Inductive Power Transfer (BIPT) Systems with Fully-compensated Series-Series (SS) Topology

A Triple Phase Shift Control Method for Bidirectional Inductive Power Transfer (BIPT) Systems with Fully-compensated Series-Series (SS) Topology

The Generalization of Bidirectional Dual Active Bridge DC/DC Converter Modulation Schemes: State-of-the-Art Analysis under Triple Phase Shift Control

The main objective of this paper is to provide a thorough analysis of currently used modulation control schemes for single-phase bidirectional dual active bridge DC/DC converters. In this article, it will be shown that single phase shift, extended phase shift and dual phase shift modulation schemes are special cases of the triple phase shift (TPS) modulation scheme. The article aims to highlight six TPS switching modes and their complements with operational constraints. Unlike previous studies that regarded TPS as a complex scheme, this paper simplifies the analysis of each mode and aims to standardize the understanding of TPS modulation for dual active bridge (DAB) converters. Power equations, range of power transferred and zero-voltage switching (ZVS) are derived for all the modes under TPS without assuming fundamental component analysis. Additionally, a generic optimization algorithm is developed to show the advantages of TPS modulation, and thus, the analysis in this paper offers a valuable insight for single-phase DAB converter designers in identifying a wide range of optimization algorithms to achieve higher efficiency under TPS modulation. This analysis contributes to the advancement of bidirectional DAB converter technology and facilitates its application in various power electronic systems.

A flexible load adaptive control strategy for efficient photovoltaic hydrogen generation system

The adaptive adjustment of the input current in proton exchange membrane electrolyzers (PEMEL) can provide several benefits, including the enhancement of PEMEL efficiency and the extension of its operating lifespan within an optimal range. This study presents a novel configuration for a photovoltaic (PV) hydrogen generation system that allows for the direct integration of PV. Moreover, the utilization of the triple-phase shift (TPS) modulation technique is implemented in order to achieve maximum power point tracking (MPPT) control within dual active bridge (DAB) DC/DC converters. The proposed strategy offers a pre-control approach for active adjustment of flexible loads to mitigate the mismatch between power output and load caused by fluctuations in renewable energy sources. This mismatch can lead to excessive current ripple, which in turn can impact the safe functioning of the PEMEL. In tandem with the analysis of the factors that contribute to ripple and the properties of the Electrical Spring (ES), relevant multiple variables are selected as control signals for the control strategy. This is done to effectively regulate the magnitude of non-essential loads and consequently reduce the ripple in the PEMEL system. The use of the ES pre-control technique effectively addresses the issue of delayed response of the PEMEL to PV oscillations, which is attributed to the large time-lag characteristics of electrolyzers. The simulation results at steady-state conditions and sudden changes in lighting conditions demonstrate concurrently that the overall control strategy yields a reduction in current stress in the DAB to 30.09% and 51.59%, respectively, enables MPPT in PV systems, and decreases the input current ripple of PEMEL to 80.1% and 57.67%, showing stronger anti-disturbance ability.

Maximum Efficiency Tracking and ZVS Realization for Wide Output Voltage Range Employing Segmented TPS Modulation Scheme

The efficiency of wireless power transfer (WPT) systems is highly dependent on the load and dc voltage gain, which may change in a wide range in electric vehicle (EV) charging applications. Besides, existing control triple-phase-shift (TPS) strategies aimed at power regulation, zero-voltage switching (ZVS) realization and maximum efficiency point tracking (MEPT) have limitations when applied to the wide output voltage application. To fill this gap, a segmented TPS modulation scheme is proposed. Considering wide-range ZVS, three different working modes are derived to achieve MEPT over the wide output voltage range. The proposed modulation scheme employs closed-loop control by integrating different working modes. In addition, the efficiency-oriented seamless transition method among different working modes is described, which can avoid the transient oscillation at the boundary of the mode transition. The proposed modulation scheme's on-state loss and switching loss are compared to the traditional TPS modulation scheme. Finally, a 1.5 kW prototype has been built to verify effectiveness of the proposed modulation scheme within the wide voltage range, and the measured efficiency can be increased by up to 0.82% in the deep buck mode and 2.20% in the deep boost mode.

Artificial-Intelligence-Based Triple Phase Shift Modulation for Dual Active Bridge Converter With Minimized Current Stress

The dual active bridge (DAB) converter has been popular in many applications for its outstanding power density and bidirectional power transfer capacity. Up to now, triple phase shift (TPS) can be considered as one of the most advanced modulation techniques for DAB converter. It can widen zero voltage switching range and improve power efficiency significantly. Currently, current stress of the DAB converter has been an important performance indicator when TPS modulation is applied for smaller size and higher efficiency. However, to minimize the current stress when the DAB converter is under TPS modulation, two difficulties exist in analysis process and realization process, respectively. Firstly, three degrees of modulation variables in TPS modulation bring challenges to the analysis of current stress in different operating modes. This analysis and deduction process leads to heavy computational burden and also suffers from low accuracy. Secondly, to realize TPS modulation, if a lookup table is adopted after the optimization of modulation variables, modulation performance will be unsatisfactory because of the discrete nature of lookup table. Therefore, an AI-based TPS modulation (AI-TPSM) strategy is proposed in this paper. Neural network (NN) and fuzzy inference system (FIS) are utilized to deal with the two difficulties mentioned above. With the proposed AI-TPSM, the optimization of TPS modulation for minimized current stress will enjoy high degree of automation which can relieve engineers’ working burden and improve accuracy. In the end of this paper, the effectiveness of the proposed AI-TPSM has been experimentally verified with a 1 kW prototype.

Dead-Time Effect and Compensation Technology for an Isolated Dual Active Bridge Converter

Aiming at deficiencies of output voltage distortion and circulating current generation caused by dead-time effect in the modulation process, a simple and feasible dead time compensation strategy is presented. Firstly, the influence of dead-time effect on the output voltage of bridge is analysed, and a dead time compensation strategy is added between the modulation signal and dead time procession. According to the current direction of the bridge, the rising edge or falling edge of the driving signal is selectively delayed to compensate for dead-time effect. Secondly, an Optimized Triple Phase-shift (OTPS) modulation strategy is adopted with minimizing leakage inductor current Root-Mean-Square (RMS) control, which minimizes current stress, achieves soft-switching operation, avoids phase-shift errors caused by Dead-Time Effect, and optimizes control performance of DC-DC converters. Finally, simulated and experimental results are added to verify the correctness and effectiveness of the proposed method.

An LCC–LCC Compensated WPT System With Switch-Controlled Capacitor for Improving Efficiency at Wide Output Voltages

In this paper, a triple-phase-shift (TPS) control strategy combining a switch-controlled capacitor (SCC) is proposed for LCC-LCC compensated Wireless Power Transfer (WPT) system to improve the overall efficiency at wide output voltages. The basic mathematical model of the system is firstly established, and the conditions for zero-voltage switching (ZVS) and load matching are described under TPS. Then, the mechanism of TPS reducing system efficiency at wide output voltages is revealed based on the established model. A SCC is employed to adjust the compensation capacitance to achieve a minimum circulating reactive power on both sides and reduce the rectifier input current. Finally, the impact of the compensation capacitance variations on the current, output power and impedance are analyzed, based on which the optimal value of adjustable capacitance for maximum efficiency is derived by further considering the established time domain model. A comparative experiment is performed with traditional TPS and the proposed control technique, which shows that the system with the proposed control technique achieves a higher efficiency over the TPS within the entire power range.

Analytical and Normalized Equations to Implement the Optimized Triple Phase-Shift Modulation Strategy for DAB Converters

A fully normalized algorithm to implement the optimal triple-phase shift (TPS) modulation strategy of the dual active bridge converter is proposed in this paper. The algorithm evaluates three simple expressions that fit the optimal solutions obtained in recent works, which allows the algorithm to be implemented in real-time and valid for the whole operating range. As a result, the converter operates under zero voltage switching conditions and minimizes conduction losses. In addition, the algorithm considers the minimum current required to guarantee zero voltage switching condition that faces undesired dead-band of switching devices effect. The proposal achieves soft transition between any operation region and fast closed-loop response with no stability concern, presenting robustness under leakage inductance deviation. Finally, the algorithm presented in this paper is verified with a 4 kW experimental prototype. Experimental results show that the algorithm proposed can be evaluated with less than 2.8 μs and allows soft transition between any operation region to be achieved. Besides, fast closed-loop changes of 750 μs through all the operating ranges, keeping minimum RMS current under zero voltage switching, are shown.

Improved Triple-Phase-Shift Modulation for Bidirectional CLLC Converters

CLLC resonant converters are an attractive option for battery charging applications due to their bidirectional power flow and high efficiency. Pulse frequency modulation (PFM) is the simple method to drive CLLC converters. However, PFM cannot regulate the output voltage under the light-load condition properly, which leads to high switching and core losses. Phase shift modulation techniques like dual-phase shift (DPS) modulation can overcome this challenge. However, more improvements are demanded due to high circulating currents in phase shift modulations. In this paper, an improved modulation technique based on triple-phase shift (TPS) has been applied in CLLC converters to improve the light-load efficiency. TPS modulation like any other phase-shift modulation, keeps the switching frequency of CLLC converters fixed at the resonant frequency under the light-load condition and regulates the output voltage by its three phase shift parameters. The improved TPS modulation has lower circulating current at the same average output current compared to DPS modulation. Therefore, higher efficiency, smaller peak, and RMS current values can be achieved under the light-load condition. In addition, the proposed TPS modulation has a better flexibility in regulating the output voltage under the light-load condition due to an extra phase shift parameter compared to DPS modulation. The proposed TPS modulation has been analyzed thoroughly in this paper and a proper selection of phase shift values has been explained to improve the efficiency of the converter. Finally, advantages of the improved TPS modulation have been validated by simulation and a 1 kW experimental setup.

Suppression of dc‐offset current in ac‐link of dual‐active‐bridge dc‐dc converter based on triple‐phase‐shift optimal control

AbstractWhen dual‐active‐bridge dc‐dc converter (DAB) with energy storage load operates in a wide voltage range and high dynamic condition, the mismatch of primary and secondary side voltages will lead to high current stress and loss, and the dc‐offset current in the high‐frequency ac link will lead to magnetic saturation of magnetic components, which will damage the devices in serious cases. Therefore, aiming at the operation of DAB in a wide voltage range, a triple‐phase‐shift (TPS) optimal control strategy is adopted, and the phase shift angles of the bridges are adjusted according to the voltage ratio, so as to optimize the electrical stress and loss. What is more, the cause and mechanism of dc‐offset current in the ac‐link are analysed. Based on the TPS optimal strategy, the static dc‐offset current is suppressed with the low‐bandwidth detection of the offset current and the dynamic dc‐offset current is suppressed with the planning the current trajectory. A small‐power prototype is built, and the effectiveness of the TPS optimal control and the static and dynamic dc‐offset current suppression is verified.

A Mode-Switching-Based Phase Shift Control for Optimized Efficiency and Wide ZVS Operations in Wireless Power Transfer Systems

This paper proposes a mode-switching based phase shift control (MS-PSC) for wireless power transfer (WPT) systems, which is able to achieve power regulation, load matching, and wide ZVS operations simultaneously without using additional dc-dc converters. Based on the mode transitions between the full-bridge, mixed-bridge, and half-bridge modes of both the inverter and the rectifier, the MS-PSC method guarantees a wide-range ZVS with minimized circulation of reactive power. Therefore, the system efficiency is improved over a wider power range compared to the conventional triple-phase-shift (TPS) control and the existing hybrid modulation control. The principles of different operating modes are analysed. Then, the implementation of the proposed MS-PSC method and the mode selection strategy are presented. Finally, the effectiveness of the proposed MS-PSC method is validated in a WPT prototype. Experimental results show that the proposed MS-PSC method can achieve a high overall efficiency in a wide power range. Compared with the conventional TPS control, the MS-PSC method further optimizes the efficiency in 10%-63% of the rated power, with efficiency improvements ranging from 1.5% to 6%. As a result, the system efficiency remains at 93.5%-96.1% in the power range of 1-10 kW, with the transformer coupling coefficient k=0.19.

Online Reactive Power Minimization and Soft Switching Algorithm for Triple-Phase-Shift Modulated Dual Active Bridge Converter

In a dc microgrid, a bidirectional dc–dc converter is an essential link between voltage bus and energy storage system (ESS). When galvanic isolation and high efficiency are required, dual active bridge (DAB) converter is preferred. Due to the instability of renewable energy sources, the DAB converter may transmit high or low power to ESS. To improve the efficiency across wide power range, this article proposes a reactive power minimization and soft switching optimization algorithm that combines the augmented Lagrangian method and triple-phase-shift (TPS) modulation. Unlike an offline algorithm with look-up table, the proposed algorithm can compute phase-shift-angle online, avoiding a large database for various working conditions. A prototype with an 800 W rated power is built, and the efficiency test results validate the efficiency improvement over other TPS-based algorithms. Furthermore, a current regulation experiment demonstrates that the proposed algorithm is suitable for ESS charging, which must deal with varying output voltage and power demand.