Resonant Power Converter Research Articles

Isolated bidirectional DC-DC Converter: A topological review

Bidirectional DC-DC converters (BDCs) are certainly an important power electronic converter for managing bidirectional power flow in various applications. It offers the ability to flow power in both directions, which is useful in systems with renewable energy sources and energy storage. BDCs are becoming increasingly important in various applications, including renewable energy systems, electric vehicles, and energy storage. The development of new BDC topologies and control strategies is expected to further improve their efficiency and performance. Non-Isolated Bidirectional DC-DC Converters (NBDCs) and Isolated Bidirectional DC-DC Converters (IBDCs) are the two main types of BDCs with different isolation properties and trade-offs in terms of size, cost and performance. Topological classification of BDCs further distinguishes various BDC types based on their configurations and voltage-boosting techniques. IBDCs are preferred over NBDCs due to high-power applications, and wide voltage range with higher efficiency; the performance of IBDCs is improving day by day. To provide a framework for comparison in implementing novel configurations or identifying the best converter for a given application, this study is concentrated on each topology and its usual applications. Soft switching converters are also discussed pointed to Resonant Power Converters (RPCs) for the application into Electric Vehicles (EVs). It is worth noting that the choice of BDC depends on the specific requirements of the application, such as power level, voltage range, efficiency, and cost. A detailed comparison, application, advantage and disadvantage table can be useful in comparing the characteristics of different BDCs and selecting the most suitable one.

Maximum Efficiency Point Tracking Algorithm for Resonant Full-Bridge Converter in Charging Applications

In this paper, a novel maximum efficiency point tracking algorithm is proposed for a resonant DC-DC power converter in charging applications. Based on a total harmonic analysis (THA), a method for minimizing the harmonic content of the input AC current is investigated. An online algorithm is proposed for achieving the maximum efficiency at the whole charging spectrum, by controlling the angle under which zero-voltage switching occurs. The suggested control algorithm is simple to implement with very low computational complexity. Additionally, an effective winding method is proposed for increasing the leakage inductance without greatly increasing the air gap, thus eliminating the need for additional resonant inductors. A prototype converter of 2kW|20A is implemented for verifying the proposed method and 98% maximum efficiency is achieved.

A Reconfigurable Two-Stage 11 kW DC–DC Resonant Converter for EV Charging With a 150–1000 V Output Voltage Range

In this paper, a reconfigurable two-stage DC/DC resonant topology with a wide output voltage range of 150-1000V is proposed for Electric Vehicle (EV) charging with high efficiency over the entire load range. The proposed topology consists of an LLC resonant converter with dual secondary sides; two interleaved triangular current mode buck converters, and three additional auxiliary switches for reconfiguration. Two possible arrangements of the proposed topology are considered and compared. The analytical model of the topology is developed, which is used for the efficiency estimation of different configurations and the design of the prototype converter. An 11kW hardware demonstrator is built and tested. The maximum measured efficiency of the converter is 97.66%, with a >95% efficiency over the complete 150-1000V range at full power. The proposed two-stage converter achieves the widest output voltage range reported in literature for resonant power converters, thereby capable of charging existing and future EVs very efficiently over any charging cycle.

Heat Distribution Analysis of Resonant Power Converter in Non-starting Air Conditioner of Commercial Vehicles

Heat Distribution Analysis of Resonant Power Converter in Non-starting Air Conditioner of Commercial Vehicles

Research on parallel control strategy of power converters based on fuzzy neural network

As pure electric vehicles shift toward intelligent technology, the energy demand for onboard equipment is on the rise. In this study, a parallel control strategy for two 3-kW DC–DC power converters was proposed to meet the power requirements of pure electric vehicle loads in this paper. First, the operation mode of the resonant power converter was analyzed. The operation mode of the power converter adopted the advantageous frequency conversion–phase shift control mode. Second, a parallel control method for Takagi–Sugeno-type fuzzy neural network converters with four inputs and a single output first-order was designed to meet the power demand based on the advantages of fuzzy control and neural networks. The neural networks can be trained automatically based on the established requirements, and the fuzzy rules formulated through fuzzy neural networks were more detailed and accurate. Finally, the proposed control strategy was validated by experiments. The experimental results showed that the proposed control strategy can ensure the stable operation of the power converter during switching under the set load. The output power of the primary and sub converters varies linearly, which can meet the load’s demand for high power. There is no need to develop higher-power power converters. These results can provide a new idea for the research of high-power power converters and reduce development costs.

Next generation induction heating: GAN vs. MOSFET based resonant power converter for residential use

Next generation induction heating: GAN vs. MOSFET based resonant power converter for residential use

A Self-Oscillated Feedback Network for Push–Pull Resonant Power Converters

A Self-Oscillated Feedback Network for Push–Pull Resonant Power Converters

Characterization of an energy efficient pulsed current TIG welding process on AISI 316 and 304 stainless steels

This paper presents the characterization of a TIG welding process carried out by means of an arc welding power supply able to provide dc or pulsed current. The arc welding power supply is based on resonant power converters and an FPGA-based control circuit. Dc and multiple pulsed operations up to 1 kHz with different pulse widths have been tested. The operation of the proposed welding power supply has been compared to that of a high-quality commercial welding machine. Regarding performance, the investigated electrical parameters are: power factor, power conversion efficiency and the energy consumption of the process. The radiography and mechanical properties of the welds have been examined. The mechanical properties of the welded joints characterized through tensile tests are the yield stress, tensile strength and the strain under maximum stress. In addition, the impact properties of the joints were determined through Charpy tests and the curves relating energy absorbed and temperature were obtained. The results show an improved performance of the proposed arc welding power supply over the commercial counterpart, with higher efficiency and power factor, as well as lower energy consumption. The yield stress and tensile strength results indicate that the welded plates using pulsed modes with the proposed power supply are comparable to the reference weld performed with dc operation using the commercial welder. Remarkably, it was observed that the ductility of the welded plates using pulsed modes with the proposed power supply outperforms those of the reference weld carried out with dc arc using the commercial welder.

A Turn-Ratio-Changing Half-Bridge CLLC DC–DC Bidirectional Battery Charger Using a GaN HEMT

This paper presents a 250 kHz bidirectional battery charger circuit using a GaN HEMT. The charger is subjected to a high-/low-side constant voltage at 200 V/20 V. The charger circuit is a hybrid of the LLC and flyback circuit topologies. Both the power output analysis and efficiency control of this circuit are simplified when the magnetization current is minimized using the low-resistance GaN HEMT. The switching frequency is controlled to match the series resonance in a way that is analogous to conventional LLC circuit controls, while the duty ratio that determines the power output and the dead time, which determines the zero voltage switching, is controlled in an analogous manner to the flyback circuit control. The charging and discharging modes were altered by applying a double-throw relay that changes the transformer turn ratio, which is different from conventional LLC designs using the switching frequency adjustment. A nominal turn ratio with Np = 35 and Ns = 3.5 for a 200 V/20 V converter can only produce an internal series resonance with no current flowing in any charging direction. The proposed circuit using a transformer with multiple windings (Np = 35, Ns,F = 4, and Ns,R = 3) was fabricated to deliver 125 W output power from the power grid battery to the vehicle battery in the forward (charging) mode and 90 W in the reverse (discharging) mode. The conversion efficiency was calculated to be as high as 97% in the forward mode and 95% in the reverse mode. The high conversion efficiency is due to the characteristics of the GaN HEMT, including low resistive and switching losses. The equations derived in this paper associate these losses with the series resonant frequency and power conversion rate, which highlight the advantages of using a GaN HEMT in this CLLC design.

Real‐time electro‐thermal modelling and predictive control design of resonant power converter in full electric vehicle applications

AbstractIn this paper, a resonant converter model is proposed that takes into account the thermal and electrical dynamics of the main components. With respect to state‐of‐art, where model‐based design approaches are often implemented off‐line, the proposed model has a low computational complexity such that it can be simulated in real‐time. This real‐time electro‐thermal model enables also the design of a predictive control algorithm, that is proposed to optimize the current control of a SiC‐based resonant converter by handling both thermal and electrical operating limits of its components. To validate the interaction between the converter model and the predictive control algorithm, validation is proposed via real‐time processor‐in‐the‐loop, with application to the on‐board charger for high‐voltage Li‐ion battery pack, typical of modern fully electrified vehicles.

GaN-Based Matrix Resonant Power Converter for Domestic Induction Heating

Flexible-surface induction cooktops must operate with a variety of induction heating loads with different behavior and power setpoints to be heated simultaneously. In this context, multi-output inverter topologies aim at achieving independent power management while featuring low power-device count and high power density. However, they suffer from limitations when applying classical modulation strategies to ensure soft switching, which is required to reduce transistor losses and achieve efficient operation. In this scenario, wide band-gap devices reduce switching losses, opening a new paradigm in power conversion where soft switching is not mandatory in order to achieve high efficiency. This paper proposes an implementation of a multi-output resonant inverter based on GaN HEMTs and evaluates various modulation strategies in terms of efficiency under different switching modes. The proposed approach is designed and experimentally validated by means of a 2-coil 2000 W prototype implementation.

Nonlinear voltage error analysis and control of resonant high precision converter

The current nonlinear distortion of power converter can cause motion trajectory error and positioning error of motor, and affect the nano motion and positioning accuracy of ultra-precision system. The resonant pole-based dual buck soft-switching power converter (RPDBSPC) topology does not​ suffer current distortion caused by blanking time, and can support the high-frequency operation. It is suitable for the field of high dynamic and high-precision motion control. In order to realize the low nonlinear distortion current, the dual buck soft-switching topology should possess high linear output characteristics, and its nonlinear voltage error needs to be suppressed. This paper analyzes the operation principle of resonant power converter, and establishes its state space average model. Based on this, the nonlinear voltage error related resonant process of soft-switching topology is researched. Combined with the resonant equivalent circuit under unbalanced voltage sharing condition and the nonlinear characteristics of switching output capacitance, the expressions of nonlinear voltage error and zero voltage time are deduced, and a nonlinear voltage error suppression method based on zero voltage time control is proposed, which effectively reduces the current nonlinear distortion of resonant power converter.

A modulation strategy for eliminating zero-crossing distortion of dual buck high-precision resonant converter

Due to no current distortion caused by blanking time, the resonant pole dual buck soft-switching power converter (RPDBSPC) can be applied to ultra-precision motor drive. The soft-switching operation can expand the switching frequency and improve the current response. Based on the resonant pole soft-switching topology, this paper proposes an in-phase modulation strategy. By analyzing the output voltage characteristics of switching nodes under different inductance current states, it reveals the mechanism of in-phase modulation to achieve nonlinear voltage suppression by adjusting the common conduction region. According to the correlation of modulated signals, the mathematical model of modulation algorithm is established, then the strategy feasibility and system stability are researched. Finally, the total harmonic distortion of output current can reach to 0.134% by applying the in-phase modulation when the bus voltage is 500V and the switching frequency is 100 kHz.

Series RLC Resonant Circuit Used as Frequency Multiplier

Currently, the design of resonant power converters has only been developed while operating in the steady state, while the design operating in the transient stage has not been considered nor reported. This paper is interested in testing the performance of the resonant circuits operating in the transient stage and finding applications where benefits can be obtained from this form of operation. One application in which it is possible to obtain benefits from designing resonant circuits in the transient state is in the area of frequency multiplication. Usually, to achieve frequency multiplication, it is necessary to resort to complex methods and special devices that increase the complexity of the design and the total cost of the circuit. This paper evaluates the performance of a series RLC resonant circuit operating in the transient stage and with an underdamped response acting as a frequency multiplier, where the oscillation frequency of the current in the resonant tank is “n” number of times the switching frequency of the square voltage source at the input with a duty cycle of D = 50%. To validate the analysis, a circuit was designed to deliver an output power of 30 watts to a resistive load, where the switching frequency of the square voltage source at the input was 500 kHz. Since a multiplier value “n” equal to fifteen was chosen, the current in the resonant tank reached an oscillation frequency of 7.5 MHz. The design methodology was validated by simulations in SPICE, complying with the established design parameters.

Electrical Schemes of Resonant Conversion of Reactive Power to Active

Problem. Today, it is extremely important to solve the problems of efficient conversion of various types of energy (solar, wind, thermal, etc.) into electricity, which is a non-alternative factor in the comfort of the existence and development of all mankind. In this regard, the undoubted interest in practically accessible technical developments aimed at solving the above problems of the modern electric power industry should be highlighted. So, for example, the transformation of reactive power into active power, which can be used to perform work for various purposes, is of interest. Goal. The purpose of this work is to propose and theoretically substantiate the effectiveness of possible schemes for a resonant reactive power to active power converter, combined by the presence of two inductively coupled active-reactive circuits and different ways of creating resonant conditions in each of them. Methodology. The calculated ratios for the theoretical substantiation of the effectiveness of the considered converter circuits are based on physically clear phenomenological provisions and a rigorous mathematical approach using the apparatus of the theory of electrical circuits. Results. For a circuit where resonance excitation is carried out by an appropriate choice of its parameters, the conditions are determined, the fulfillment of which minimizes the influence of the proposed circuit on the processes in the reactive power source at the maximum current in the converter load. The real parameters of the circuit are calculated, where, with the proper choice of its parameters, it is possible to carry out a real conversion of the input power (conversion coefficient ~ 1.0) with a minimal effect on the current in the reactive power source (decrease to ~ 8,5%). For a circuit with an additional source of harmonic voltage, it is shown that with an appropriate setting of a third-party source, it is possible to completely eliminate the negative effect of electromagnetic processes in the converter circuit on the output voltage and current of the reactive power source. Originality. The scientific novelty of this work lies in the proposal and analysis of possible schemes of the resonant converter of reactive power into active power, combined by the presence of two inductively coupled active-reactive circuits and different ways of creating resonant conditions in each of them. Practical value. The theory and numerical assessments of the characteristics of the processes occurring in the proposed circuits of the resonant reactive power converter are important for further experimental studies, as well as for formulating recommendations for the manufacture of various options for operating devices for the appropriate purpose.

Design of Electric Vehicle Battery Charger With Reduced Switching Frequency Variation

This article presents the design of an electric vehicle (EV) battery charger isolation stage for minimizing switching frequency variation with the proposed duplex control. Traditionally, the realization of an EV charger with a resonant power conversion stage involves extreme frequency variation in the constant voltage (CV) mode resulting in switching losses, imposes severe constraints on the optimal design of magnetics, and presents control complexities due to secondary resonance and degraded pulsewidth modulation resolution. In this context, reported hybrid control strategies are complex and entail the simultaneous variation of control variables. In order to simplify control complexity and design constraints, the EV charger isolation stage with the quadruple rectifier and employing the proposed duplex control is presented with notable frequency reduction. Furthermore, the effect of high-frequency transformer nonidealities on the soft-switching range is delineated. The proposed duplex control contributes to the efficiency enhancement of the EV charger over a comprehensive range during CV charging, ensures soft switching, and prevents secondary resonance. It also offers continuous resonant current to overcome the underutilization of the transformer arising from high-frequency distortions. To validate the presented analysis, a 1.25-kW hardware prototype is designed and tested in the laboratory, and experimental results are presented.

Generalized Average Modeling of a Dual Active Bridge DC-DC Converter with Triple-Phase-Shift Modulation

This paper shows an elaboration of an equivalent electrical circuit of a Dual Active Bridge (DAB) and its application as a versatile tool for steady-states analysis in wide range of operating conditions. This work analyses the converter which is controlled with a coherently defined Triple Phase-Shift (TPS) modulation which allows appropriate switching functions to be written, thus enabling the circuit’s state-space equations to be derived. Due to this approach, a Fourier series expansion may be easily applied to utilize Generalized Averaged Modeling (GAM)—a convenient method for modeling resonant and quasi-resonant power converters. Moreover, this paper shows the utilization of the GAM model higher harmonics’ complex magnitudes to calculate the steady-state power characteristics for bidirectional operation; additionally, a method for a particular state variable waveform signal reconstruction is presented. All the discussed model properites are validated with a 1.5 kW 100 kHz SiC-based DAB prototype.

SiC-Based Resonant Converters With ZVS Operated in MHz Range Driving Rapidly Variable Loads: Inductively Coupled Plasmas as a Case of Study

Wide band-gap resonant converters operating with zero voltage switching (ZVS) recently proved the conversion of up to <inline-formula><tex-math notation="LaTeX">$25 \,\mathrm{k}\mathrm{W}$</tex-math></inline-formula> at <inline-formula><tex-math notation="LaTeX">$3 \,\mathrm{M}\mathrm{Hz}$</tex-math></inline-formula> with an efficiency of <inline-formula><tex-math notation="LaTeX">$\approx$</tex-math></inline-formula><inline-formula><tex-math notation="LaTeX">$94 \%$</tex-math></inline-formula>. This is of special interest for any application where power in middle frequency range is required since typically achieved efficiencies for those frequencies are in the range of <inline-formula><tex-math notation="LaTeX">$60\% \hbox{--}70\%$</tex-math></inline-formula>. Inductively coupled plasma (ICP) based applications would significantly benefit from this fact, but they entail special driving challenges. ICP loads exhibit strong impedance variations during ignition and operation, which means a high limitation factor when driving them with resonant converters. This article offers a deeper look into this topic through the example of a <inline-formula><tex-math notation="LaTeX">$10 \,\mathrm{Pa}$</tex-math></inline-formula> Xenon lamp. The ignition transient is measured and analyzed while driving the system with a Silicon Carbide (SiC)-based resonant converter. An FEM simulation modeling the electromagnetic, thermal, mechanical, and plasma properties is also performed. The results are contrasted with the corresponding measurements showing as well the simulation usefulness as a design tool. Theoretical calculations of the intrinsic limits for ZVS resonant power conversion are also offered. This provides an insight into which analysis and control methods would make ICP loads compatible with these converters and, therefore, able to benefit completely from their efficiency and power density benefits.

Wireless Power Transmission by Resonant Power Converters for Charging of EVs

Wireless Power Transmission is gaining traction as a versatile, safe, convenient and self-contained charging option for electric vehicles and plug-in hybrids. The separation between the transmitter coil and the vehicle mounted receiver coil contributes to WPT's safety. Wireless charging may also be used in extreme weather without being impacted by snow or rain, and without the use of bulky cables or heavy-duty plugs. Wireless power transmission is flexible and convenient not just because wires or connectors are not required, but also because charging becomes completely self-contained. As advances in this domain continues, it's not impossible to imagine a vehicle capable of sensing magnetic field or a parking assist capable of positioning itself over a primary pad for optimal alignment and autonomous charging. By incorporating WPT into EVs, the challenges of charging time, range, and cost may be easily overcome. In the broad market adoption of electric vehicles, battery technology is no longer significant. It is believed that the cutting-edge results would inspire academics to continue developing WPT and expanding EV.

Research on current‐type high frequency resonant power converter based on magnetic energy recovery switch

LCL resonant converters have been widely used to get a constant current output. This paper proposes an LCL resonant converter based on the magnetic energy recovery switch (MERS), which adjusts the output current of the converter by controlling the paralleled equivalent capacitance, as responding to the parameter errors or input voltage disturbance. Firstly, based on the equivalent model of the LCL resonant converter, the effect of variable capacitive impedance on the output current characteristics of the converter is analysed. Then the topological structure of MERS is introduced and its working principle as a controllable capacitive impedance controller is further explained. On this basis, the operating characteristics and soft switching characteristics of the proposed topology in each complete working cycle are analysed in detail. By controlling the phase shift angle between the output voltage of bridge and the fundamental component of MERS voltage, the equivalent capacitance of the MERS is changed, and the resonant frequency of the converter is accordingly adjusted to accurately compensate the output current against the input voltage disturbance. Finally, the effectiveness and feasibility of the MERS applied to the LCL resonant converter are verified by simulation and experiments. Besides, its operating characteristics are analysed and evaluated.