Resonant Tank Research Articles

Analysis and Design of an Integrated Bidirectional Three-Phase AC–DC Resonant Converter

This paper proposes a novel isolated bidirectional AC-DC converter where the front end and primary side of DC-DC isolated converter are merged giving rise to 25&#x0025; fewer devices. Owing to the integrated topology the devices of the proposed converter are naturally soft switched and the size of the filtering components in the AC-DC stage is reduced compared to a low frequency hard switched AC-DC stage. A Space Vector Modulation (SVM) and control technique is proposed for generating switching pulses for DC link voltage control and bidirectional power transfer. A design optimization technique is proposed to mathematically determine the switching frequency of the converter and subsequently, the resonant tank parameters based on the operating conditions, topology, modulation, and the Wide Band Gap (WBG) Silicon Carbide (SiC) device characteristics. The proposed converter and its design approach are validated through prototyping for a scaled-down bidirectional charger for warehouse Electric Vehicles (EVs), and experimental results from two test cases, one with the actual grid with an input ac line (<i>i.e.,</i> 208&#x00A0;V) voltage and second with an AC power supply of input line (<i>i.e.,</i> 400&#x00A0;V) voltage. The former is tested for a peak power rating of 2.5&#x00A0;kW and the later is tested for a 5&#x00A0;kW output power. The switching frequency from the proposed optimization method is determined to be around 130&#x00A0;kHz for both cases. Peak efficiency of 95.3&#x0025; is achieved. The battery voltage varies from 350-600&#x00A0;V.

Three‐phase bidirectional isolated LLC resonant DC‐DC converter for DC microgrid applications

SummaryDC microgrids rely strongly on bidirectional dc‐dc converters responsible for managing the power flow among distinct loads and renewable energy sources like fuel cells and batteries. In this context, this work presents a three‐phase inductor‐inductor‐capacitor (LLC) resonant dc‐dc converter with high‐frequency isolation and bidirectional power flow capability, employing phase‐shift control and frequency modulation. The resonant tank takes advantage of using the leakage inductance and the magnetizing inductance of the high‐frequency transformer (HFT), which allows for improving power density. The active switches operate with a fixed duty ratio of 50% so that the converter can always achieve zero‐voltage switching (ZVS). The mathematical analysis is carried out based on a single‐phase representation of the converter, which considers only the fundamental components. A dynamic model is derived using the gyrator theory, which allows representing the converter as a frequency‐controlled current source to regulate the output voltage. In addition, the power flow direction is determined from the estimation of an ideal phase‐shift angle for each frequency aiming to control the output power. An experimental prototype is implemented and thoroughly assessed to demonstrate that the introduced topology is feasible for dc microgrids and other applications that require bidirectional power flow.

Research and optimization design of two-stage isolated inverter power supply based on series quasi-resonance

PurposeThis paper aims to solve the problems of large hard switching loss and unclear resonant parameter design in the existing inverter power supply topology.Design/methodology/approachThis paper proposes a simple and reliable two-stage isolated inverter composed of series quasi-resonant push-pull and external freewheeling diode full-bridge inverter. The power supply topology is analyzed, the topology mode is analyzed, the mathematical model of the converter is established and the DC gain of the converter is deduced. The relationship between the load and the output gain of the resonant tank is presented, a new resonant parameter design method is proposed, and the parameter design of the resonant element of the converter is clarified.FindingsThe resonant components of the converter are designed according to the proposed resonant parameter design method, and the correctness of the method is verified by simulation and the development and testing of a 500 W experimental prototype. After experimental tests, the peak efficiency of the experimental prototype can reach 94%. Because the experimental prototype achieves soft switching, the heat generation of the switch is greatly reduced, so the heavy heat sink is removed, and the volume is reduced by about 30% compared with the traditional power supply, and the total harmonic distortion of the output voltage is about 2%.Originality/valueThe feasibility of the scheme is verified by experiments, which is of great significance for improving the efficiency of the inverter power supply and parameter optimization.

Steady-State Performance Optimization of Dual-Bridge Series Resonant DC/DC Converters

By establishing the mathematical model of the resonant-tank root-mean-square (RMS) current of the dual-bridge series resonant DC/DC converter (DBSRC), this paper comparatively analyzes the performance of the DBSRC under asymmetric-phase-shift (APS) control. This paper analyzes the influence of the dead-time gap on APS control. Then, a steady-state performance optimization strategy is proposed in this paper for DBSRC under APS control considering the dead-time gap, and the proposed control scheme is analyzed and implemented. The steady-state performance optimization strategy can minimize the resonant tank RMS current, extend the ZVS range, eliminate the influence of the dead-time gap and enhance the transmission efficiency of the DBSRC. Besides, the resonant tank parameters sensitivity of the proposed optimization strategy is discussed, and a simple parameters estimation strategy is proposed. At last, the excellent performance and theoretical analysis of the steady-state optimization strategy have been verified in this paper.

Robust Class E2 Wireless Power Transfer System Based on Parity–Time Symmetry

Thanks to the superiority of zero-voltage switching (ZVS), the Class E <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> topology has become a promising candidate in wireless power transfer (WPT) at medium and small power levels. However, in practical applications, it is a challenging and significant issue to maintain robust WPT under varying transfer distances, especially for the highly sensitive Class E power amplifier (PA). To solve this issue, the parity–time (PT) theory is initially developed into the Class E <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> WPT system. A general design procedure for the PT-symmetry-based Class E <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> WPT system is proposed, including the parameters of the Class E PA, resonant tank, and Class E rectifier. The power losses and efficiencies of the above-mentioned components are analytically derived as well. The ZVS operation is quantitatively described for the PT-symmetry-based Class E <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> WPT system, demonstrating that the maximum phase variation with coupling coefficient is rather small and independent of the natural resonant frequency, thereby achieving robust and highly efficient power transfer. Finally, the prototype with current feedback control to guarantee the PT mechanism and ZVS is built. The experimental results illustrate that under various coupling coefficients, robust and efficient power transfer is realized by a 165-W prototype with about 92.6% efficiency.

Nonlinear Resonance Characteristics Analysis of DBD Load Based on State Plane Trajectory

Dielectric barrier discharge (DBD) loads and driving converters are widely utilized in low-temperature plasma generation, but their resonant tanks have typical nonlinear characteristics with control issues. The state plane trajectory analysis is used in this article to investigate the resonant behavior of a DBD load. The converter's working principle and state plane modeling are first discussed. The impact of a high-ratio step-up transformer with parasitic capacitance is then explored, and the updated trajectory model is examined. The DBD platform is created to verify the suggested model, and the associated experimental data are provided. The results of the experiment demonstrate that the discharge trajectory is a zone with distinct borders. The trajectory equations can be utilized to calculate the load equivalent capacitance, and the difference in the boundary equivalent capacitance represents the discharge intensity. The pattern of resonant frequency variation with discharge power is given. The impact mechanism of discharge phenomena and resonance characteristics is discussed.

A Novel LCL Resonant Converter With Inherent CC-CV Output for On-Board Chargers of Plug-In Electric Vehicles

The <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">LLC</i> Resonant converter is widely used in on-board charger applications for its high efficiency. However, conventional <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">LLC</i> converter with pulse-frequency-modulation suffers from a wide switching frequency range for realizing constant current (CC) and constant voltage (CV) charges. To address this problem, different from the traditional solution, a novel <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">LCL</i> resonant converter operating at a fixed resonant frequency with inherent CC and CV output characteristics is proposed in this letter. In the proposed concept, the CC and CV charges are accomplished by the special <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">LCL</i> tank. With the increasing of battery voltage during charging process, the resonant tank of the proposed converter is equal to the conventional <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">LCL</i> tank and <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">LC</i> tank for CC mode and CV mode, respectively. Thus, the sensing and control circuits are canceled while the wide zero-voltage-switching operation for primary switches and zero-current-switching for secondary diodes still be maintained. Therefore, the fixed resonant frequency operation, high efficiency, high reliability, and low cost are key features of the proposed converter. A 1-kW prototype with 400 V input and 250–400 V output is built and tested. The full load efficiency of 96.7% and higher than 96% for the CC mode were both achieved. The experimental results demonstrate the advance and validity of the proposed converter.

A Medium Voltage Input Multiport Isolated Output DC Transformer With Power Self-Balancing and Output Fault Isolation

Medium voltage dc (MVDC) converters with multiple output ports have the challenges of series input module power balancing control and fault isolation between output ports. This paper proposes a new medium voltage input multiport isolated output dc transformer topology. The proposed topology can be extended to up to 2k-1 output ports of different voltages with k modules input connected in series. Moreover, the proposed topology has the voltage self-balancing feature of input modules since they are coupled via the balancing capacitors. Current self-balancing of all MOSFETs is also achieved, as the equivalent impedance of multiple voltage sources discharging to multiple loads is the same under the influence of the split resonant inductor. Besides, the proposed topology can limit the shorted current in the output port automatically without affecting other ports, due to the impedance of the resonant tank of the faulty port being clamped. A 2kV dc input with three output ports of 410V, 380V and 40V prototype is built to verify the feasibility of the proposed topology. The results show that the proposed topology has multiple module power self-balancing feature, and can improve the reliability of the multiport power supply systems. Therefore, it has good prospects for subsea dc power distribution systems and ship electric power distribution systems.

Retuning high Q inductive power transfer systems at MHz frequencies: a switched capacitor design method incorporatingCOSS

AbstractHigh Q coils are required by inductive power transfer (IPT) links to attain reasonable levels of power transfer especially for loosely coupled links such as those used for small, deeply implanted medical devices. However, the high Q feature makes IPT systems strongly dependent on operating frequency which must be matched in the primary and secondary resonant tanks. Consequently, power transfer is sensitive to resonant frequency shifts due to component aging and environmental factors. Here, a switched capacitor (SC) network is developed to maintain tight matching and enhance system robustness. The combination of high voltage and high frequency required to achieve power transfer to deeply implanted devices makes the SC network design challenging. High frequencies require small tuning capacitance and high voltage requires MOSFETS with large output capacitance (COSS) resulting inCOSShaving a significant effect on tuning frequency. This paper proposes a parameter design method incorporatingCOSSto eliminate the uncertainty of voltage relatedCOSS. In the experiment, the SC network broadens the effective bandwidth from 37 to 585 kHz at the centre frequency of 6.50 MHz. Across a frequency sweep, the worst case in transfer power drop is −0.43 dB, which demonstrates sufficient immunity to parameter deviations.

A Novel ZVS/ZCS Push-Pull LC Resonant DC-DC Converter for Energy Sources

In this paper, a novel soft switching push-pull LC resonant DC-DC converter for energy sources is presented. In a high step-up converter, the input of primary side possesses low voltage and high current, so the losses caused by the current account for most of the total power loss. At the same time, the high-voltage stress of the high-voltage output components on the secondary side is also a major problem. Therefore, a high-gain isolated push-pull converter with a secondary-side resonant circuit is proposed, so that the primary-side switches have zero voltage switching (ZVS) and the secondary-side diodes have zero current switching (ZCS). The push-pull structure can reduce the number of active switches, so that the total power loss on the primary side can be reduced. The converter has a resonant tank circuit arranged between the secondary side of isolation transformer and the high-voltage output rectification module. The high-voltage output rectifier module adopts a full-bridge architecture suitable for high-voltage coupling connection. The low-side power switching module adopts a push-pull architecture suitable for low-voltage and high-current applications. The resonant tank circuit uses an inductor–capacitor (LC) structure to improve the resonant tank circuit, which achieves soft switching during power transfer, increasing the efficiency of the converter and improving the electromagnetic compatibility. The main advantage of this technology is that the secondary-side leakage inductance of transformer and the resonant capacitance are connected in series to achieve ZVS for switches and ZCS for diodes. Finally, a prototype of a high-gain push-pull resonant converter was established. The converter was operated at a fixed switching frequency of 135 kHz and a duty cycle of approximately 0.5. The efficiency of the converter can reach 97.1% under experimental tests at an output voltage of 400 V and a rated output power of 500 W.

Performance enhancement of piezoelectric bulk mode MEMS mode-matched gyroscopes based on a secondary phase feedback loop

This work investigates the performance enhancement of piezoelectric bulk mode mode-matched gyroscopes based on a secondary phase feedback loop. An independent phase feedback loop realized by a lock-in amplifier is applied on a 10 MHz multiple ports piezoelectric device to harness its effective stiffness and damping factor for better gyroscope performance. The multiple ports device is designed based on support transducer topology with eight transducer arms, some of which drive the central resonant tank into a secondary elliptical mode. Open-loop measurement with varied phase delay is adopted to carry out the best working condition (i.e. higher Q-factor, smaller frequency split). Therefore, the measured scale factor results in a 1.56 times improvement through boosting the Q-factor of the driving mode. The minimum frequency split compensated by the phase feedback could reach 13.4 ppm with a tuning phase of 60° and tuning voltage of 0.1 V. The bias instability of the proposed gyro through the help of phase feedback loop could be reduced by 2.13 times. The achievement in this work has shown that the phase feedback mechanism could indeed help to improve the performance of the resonant transducers.

Design and analysis of isolated high step-up Y-source DC/DC resonant converter for photovoltaic applications

ABSTRACT This paper presents the design and analysis of an isolated high step-up Y-source DC/DC converter for photovoltaic systems. At high switching frequencies, the conventional impedance source converter (ISC) experiences higher switching losses. To mitigate this, a high gain soft-switched frequency-modulated Y-source DC/DC converter is proposed. Here, soft switching is implemented on the Y-source impedance converter by creating quasi-resonance during a shoot-through instant. Thus, quasi-resonance occurs by an LC resonant tank, and it is formed using a resonant capacitor and leakage inductance of a transformer. It ensures that all the active switches are turned off with zero current switching (ZCS) and the voltage stress on each switch is much lower than the output voltage with lower turn-off voltage spikes. Thus, it eliminates the need for a snubber circuit. The output voltage is regulated by frequency modulation with the ON period of all four active switches kept constant. The converter can also deliver a continuous input current (CIC) and high voltage gain with a small shoot-through duty ratio . The galvanic isolation of the converter helps to eliminate the leakage current issues and safety hazards faced by the non-isolated counterparts. The proposed topology has all the inherent characteristics of a typical impedance source DC/DC converter with higher conversion efficiency over a wide range of output loads. The proposed converter achieves 96.46% of full load efficiency. Finally, a 200W prototype is built and tested in the laboratory to verify the converter design and performance.

A Study and Implementation of Inductive Power Transfer System Using Hybrid Control Strategy for CC-CV Battery Charging

In this paper, a hybrid control strategy is studied and implemented on an Inductive Power Transfer (IPT) system to simultaneously realize zero-voltage switching (ZVS) and constant current (CC) and constant voltage (CV) battery charging. A steady-state analysis of pulse frequency modulation was conducted, based on the characteristic of voltage gain versus switching frequency, and CC and CV charging modes were promised. The ZVS of the inverter was obtained by satisfying the minimum requirement of full discharge of the junction capacitor on the MOSFETs using a commutation current during the dead-time interval. Two control degrees of freedom are needed to realize the two control targets. This hybrid control strategy adopts a self-oscillating (SO) control to achieve ZVS and phase shift (PS) control and a constant output for the series–series (SS)-compensated IPT system. To validate the hybrid control strategy, a 1.6 kW prototype with 360–440 V input voltage and 250–400 V output voltage was built and the experimental results show that the peak efficiency can reach 96.1%. Compared with the conventional variable frequency (VF) control, the hybrid control method proves that an additional control variable can fulfill the control target in a more flexible manner, which makes the switching frequency close to the resonant frequency during the charging process, minimizing the reactive current in the resonant tank and improving system efficiency.

Investigation of resonant tank topologies performance in wireless power transfer applications

ABSTRACT Wireless power transfer (WPT) has been developed as a suitable candidate for energy transfer in various applications, recently. Resonant tank is the main passive part of such systems and various topologies are introduced to improve WPT systems performance. Characteristics of these topologies definitely affect system overall performance. Therefore, each topology’s specification and performance indexes should be evaluated and compared to choose a suitable one for a required application. In this paper, the characteristics and behaviour of voltage gain, input admittance and efficiency of well-known compensation topologies are thoroughly investigated for the first time. By calculating the voltage gain sensitivity, some analysis are performed on typical compensation including SS, SP, LCL-S, LCL-P, LCC-S, LCC-P and double-sided LCC under key parameter variations such as load resistance, switching frequency and coupling coefficient. In addition, by introducing a new formula for efficiency, the effect of resonant tank elements on efficiency is studied analytically which has not been performed before. In order to evaluate the theoretical analysis, the performance of all compensation topologies is investigated in MATLAB environment. By employing prototype SS and SP compensated inductive power transfer (IPT) test-bed system, some experimental verification are performed and the results confirm the analytical and numerical simulation findings.

Battery Internal Temperature Measurement Using LC Resonant Tank for Battery Management Systems

This paper suggests an embedded battery impedance measurement based on an Inductor Capacitor (LC) resonant tank to measure the battery’s internal temperature for battery management systems (BMS). The purpose of the BMS is to provide state-of-charge (SoC) balancing and the preheating mechanism at sub-zero temperatures. Battery Impedance Spectroscopy (BIS) for battery internal temperature measurement is achieved by an LC resonant tank connected to the batteries in parallel to induce created resonant current and voltage into the battery. The peaks of the voltage and current waveforms are measured and recorded. Then, the resistance of the battery can be calculated by comparing the peak voltage and current waveforms. Since the resistance of the battery is affected by the battery’s internal temperature, the internal temperature of the battery can be estimated. The benefit of using the LC tank for the battery’s internal temperature is to reduce data processing since no window and Fast Fourier Transform (FFT) is needed for this method. In addition, the proposed method measures the battery’s internal temperature without any internal or external temperature sensor. Power Simulation (PSIM) simulation software is used in this proposed method. Panasonic batteries 18650 and a dSPACE DS1104 are used for the experiment to verify the proposed method. The proposed method shows that the LC resonant tank can measure three batteries B1, B2, and B3 internal resistance with 17.87%, 18.14%, and 17.73% errors compared to the Frequency Response Analyzer (FRA). In addition, the total time needed for balancing is 400 s, and the total energy consumed by the preheating mechanism is 0.214%/°C to preheat the lithium-ion batteries (LIBs) from −5 °C to 10 °C.

Uniform and Simplified Small-Signal Model for Inductive Power Transfer Systems

This article explores the unification and simplification of the small-signal model for representative inductive power transfer systems. Various famous compensations are included, such as the S–S, LCC–S, and LCC–LCC. Through system decomposition, the uniform model concept is applied to the inverter, rectifier, and resonant tank. Meanwhile, the model complexity and similarity are discussed for various resonant tanks, and proper simplification is used to reduce the model order. The uniform equivalent circuit model is finally proposed for the target systems, based on which the explicit transfer function can be represented by a general polynomial equation. The model order of the S–S, LCC–S, and LCC–LCC systems are five, two, and five, respectively. The experiment shows the model is accurate up to one-fifth of the switching frequency for all the target systems.

A Three-Phase Single-Stage ac/dc Converter Based on Swiss Rectifier and Three-Level LLC Topology

<italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">LLC</i> resonant converter is widely used due to its soft switching, high power density, and high efficiency. To incorporate the merits of the <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">LLC</i> resonant tank into a three-phase single-stage ac/dc converter, this article proposes a three-phase single-stage ac/dc converter based on Swiss rectifier and three-level <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">LLC</i> topology. It takes advantage of the high-efficiency Swiss rectifier to convert three-phase ac voltages into three variable dc voltages and interface a three-level <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">LLC</i> resonant circuit. With help of the <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">LLC</i> resonant tank, all the high-frequency three-level switches achieve soft switching. To both regulate the output voltage and achieve three-phase power factor correction, the frequency modulation in combination with the duty cycle control strategy is employed by splitting the resonant current into three parts and then forming three phase sinusoidal currents. The proposed converter's detailed operation principles, steady-state characteristics, and design considerations are given. Finally, a 10 kW experimental prototype with three-phase 220 Vac inputs and 500 Vdc output is built to verify the effectiveness and feasibility of the proposed topology and its control strategy.

High-Gain Bidirectional LCLC Resonant Converter With Reconfigurable Capability

A reconfigurable gain circuit is proposed for an <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">LCLC</i> resonant converter with bidirectional capability considering wide varying redox flow battery source. A suitable hybrid control scheme for <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">LCLC</i> resonant converter with secondary synchronous rectifier is proposed in this work. The proposed reconfigurable circuit enables to configure secondary bridge as an active voltage doubler, full-bridge circuit during forward power transfer mode and reverse power transfer mode, respectively. The reconfigurability helps significantly to design a transformer with lower secondary turns and achieve desired high gain. The reduced transformer secondary turns result in reduced transformer parasitics. The presence of <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">LCLC</i> resonant tank helps to provide the additional gain; the hybrid control scheme ensures zero-voltage switching turn- <sc xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">on</small> for the primary, and secondary synchronous <sc xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">mosfets</small> throughout the operating range. The proposed converter is analysed using fundamental harmonic approximation. The proposed reconfigurable gain circuit and hybrid control scheme is verified experimentally for an 800 V/1 kW hardware prototype fed from 24 to 54 V input.

Pulse Frequency Modulated Interleaved Boost-Integrated LC Series Resonant Converter With Frequency-Free Designed Transformer

In this article, we propose a novel interleaved boost-integrated <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">LC</i> series resonant converter, in which the series resonant tank is located on the secondary side. Moreover, the input and output of the interleaved boost unit are in series directly, which is helpful to reduce the voltage stress of the output filter capacitor of boost unit. With the proposed pulse frequency modulation, except for that the output voltage can be controlled as constant under different input voltages, another feature is that the high-frequency transformer design is related to the series resonant frequency instead of the switching frequency. Hence, the proposed converter can operate under a very wide switching frequency range with a constant maximum magnetic flux density. The zero voltage switching and zero current switching can be achieved for all switches diodes. Finally, a 500-W prototype with a switching frequency range from 60 to 200 kHz is built to verify the operation principles of the proposed converter and modulation.

A Novel Bidirectional Wider Range of Boost-Buck Three-Level LCC Resonant Converter as an Energy Link

In order to maintain different voltage levels between the front and rear dc terminal bus derived from new energy industry, a novel bidirectional wider range of boost-buck three-level LCC resonant converter as an energy link is proposed by combining the LCC resonant tank module with a particular three-level coupling cascaded neutral point clamping active bridges, which is composed of two three-level neutral point clamping bridge arms. Furthermore, the converter can, respectively, establish forward LCC and backward SRC working modes to maintain unified wider bidirectional voltage gain range between the input and output by asymmetric structure of LCC resonant tank module that boost-voltage is enabled by equivalent principle of conventional LCC resonant converter and buck-voltage is enabled by equivalent principle of conventional series resonant converter, while, a unified bidirectional boost-buck voltage gain matching control strategy is designed with an optimization about parameters of LCC resonant tank module under realizing of zero voltage switching-on and reducing of reactive power losses. Finally, according to the simulation platform and experimental prototype, it can be shown that the practical voltage gain is closed to the theoretical designed gain and converter has good dynamic performances after realizing of soft-switching in each mode.