Series Resonant Power Converter Research Articles

Design and Analysis of Series Loaded Resonant Converter fed by Standalone/PV Source

The deficiency of power is an enormous issue due to higher growth demands among the utility customers which led the focus on renewable energy sources for electricity generation. Solar energy has gained high popularity due to highly abundant, clean, economical and sustainable when compared to other alternative energy sources. The DC-DC converter topologies are used in solar photovoltaic (PV) applications for power conversion due to less cost, highly reliable, highly efficient, and robust operation. These converters incorporate a wide variety of voltage variations and protection against overvoltage. In the recent times, solar power converters using various soft switching techniques due to high switching frequencies which reduce the size, cost, weight and loss of the converter. The series resonant power converters are one such soft switching converter which is widely employed due to their high - efficiency with the benefit of low switching losses. The paper confers on the analysis of Series Loaded Resonant Converter with low loss switching by applying solar PV as an input source. The converter behaviour is observed in various operating modes concerning the resonant frequency. The design parameters of the proposed converter are validated in MATLAB/SIMULINK environment.

Analytical Switching Model of a 1200V SiC MOSFET in a High-Frequency Series Resonant Pulsed Power Converter for Plasma Generation

The circuit parasitic components have a significant effect on switching performance in the high-voltage and high-frequency pulsed power converter. The SiC MOSFET has better electrical characteristics than Si MOSFET and it is preferable in this application. In this paper, the characteristics of comparative study between Si and SiC MOSFET is provided first. Then, a converter-level analytical switching model for a 1200 V SiC MOSFET is proposed in a high-frequency series resonant pulsed power converter for the application of plasma generation. To increase the accuracy of predicting the behavior of the SiC MOSFET, the proposed analytical model involves all parasitic components in the converter, including the nonlinearity of the junction capacitances and transconductance, stray inductances from the package, printed circuit board (PCB) and transformer, parasitic capacitances from the transformer, and the capacitive load of plasma. The turn-on and turn-off transitions are analyzed in detail and the modeling mathematical equations are resolved by the MATLAB ode-45 command. The accuracy of this model is validated by comparing the analytical, LTspice simulated and experimental waveforms of a 400 VDC input, −8.2kV output prototype. The proposed model enables us to evaluate and optimize the switching solution of a SiC MOSFET for the pulsed power converter.

Resonant inductive power transfer for an E-bike charging station

This paper presents the design and the experimental tests of an E-bike 300-W battery charger for a cyclo-station based on wireless power technology. In particular, a series resonant inductive power converter with an E-geometry magnetic core topology is proposed. A mathematical model is developed and a performance analysis is conducted to determine the voltage transfer function, maximum power transfer capability, efficiency for different air-gaps (1–3cm), and misalignments (0.5–1.5cm). Also, it is performed analytical and experimental investigations of the minimum and maximum relative frequency points of active input power and efficiency in order to determine how these points changed as the resistance load varied. The results of the analyses indicated that the maximum frequency points of active input power are different from the maximum frequency points of efficiency and the zero-frequency points of reactive input power. This means that maximum power transfer and efficiency conversion are not obtained in correspondence with the resonant frequency. For this purpose, it is conducted a wide frequency characterization of 30–50kHz around the designed resonant frequency of 40kHz. An iterative electrical and magnetic design procedure is proposed based on 3D finite element analysis. Simulation and experimental results are presented for a full-sized prototype. The design of the E-bike battery charger is validated in terms of rated input voltage and output power for different air-gap configurations.

Research on Inductive Power Charging Device of Unmanned Ground Vehicle

It is important to charge accumulator automatically on unmanned ground vehicles. A kind of inductive power charging system, with rotary type coupler and series-resonant power converter of full bridge, is designed. The working progress of resonant circuit and main circuit is simulated. The result of experiments shows that the simulation model of main circuit agrees well with practice and can instruct design of power converter in the future. The efficiency of power transferring decreases with coupler air gap increasing. The designed inductive charging device can charge accumulator with constant current while the air gap is 1.2 mm.

Series resonant ZCS‐PFM DC‐DC power converter with high‐frequency high‐voltage transformer link for high‐power magnetron drive

AbstractThis paper presents a single lossless inductive snubber‐assisted ZCS‐PFM series resonant DC‐DC power converter with a high‐frequency high‐voltage transformer link for industrial‐use high‐power magnetron drive. The current flowing through the active power switches rises gradually at a turned‐on transient state with the aid of a single lossless snubber inductor, and ZCS turn‐on commutation based on overlapping current can be achieved via the wide range pulse frequency modulation control scheme. The high‐frequency high‐voltage transformer primary side resonant current always becomes continuous operation mode, by electromagnetic loose coupling design of the high‐frequency high‐voltage transformer and the magnetizing inductance of the high‐frequency high‐voltage transformer. As a result, this high‐voltage power converter circuit for the magnetron can achieve a complete zero current soft switching under the condition of broad width gate voltage signals. Furthermore, this high‐voltage DC‐DC power converter circuit can regulate the output power from zero to full over audible frequency range via the two resonant frequency circuit design. Its operating performances are evaluated and discussed on the basis of the power loss analysis simulation and the experimental results from a practical point of view. © 2005 Wiley Periodicals, Inc. Electr Eng Jpn, 153(3): 79–87, 2005; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/eej.20126

Series Resonant ZCS-PFM DC-DC Power Converter with High-Frequency High-Voltage Transformer Link for High-Power Magnetron Drive

This paper presents a single lossless inductive snubber-assisted ZCS-PFM series resonant DC-DC power converter with a high-frequency high-voltage transformer link for industrial-use high power magnetron drive. The current flowing through the active power switches rises gradually at a turned-on transient state with the aid of a single lossless snubber inductor, and ZCS turn-on commutation based on overlapping current can be achieved in wide range pulse frequency modulation control scheme. The high-frequency high-voltage transformer primary side resonant current always becomes continuous operation mode, by electromagnetic loose coupling design of the high-frequency high-voltage transformer and the magnetizing inductance of the high-frequency high-voltage transformer. As a result, this high-voltage power converter circuit for the magnetron is possible to achieve a complete zero current soft switching under a condition of the broad width gate voltage signals. Furthermore, this high-voltage DC-DC power converter circuit can regulate the output power from zero to full over audible frequency range because of two resonant frequency circuit design. Its operating performances are evaluated and discussed on the basis of the power loss analysis simulation and the experimental results from a practical point of view.

Design of a contactless battery charger for cellular phone

In this paper, the design of a contactless charger for the lithium-ion battery of a cellular phone is presented. In this charger, the primary core of the transformer is in the charger unit and the secondary core is in the telephone. The gap (3 mm) between them is the thickness of the two plastic cases. The transformer core design for the maximum coupling coefficient with the size constraint on the secondary side is presented. Analysis of the primary-side series resonant power converter with the loosely coupled transformer is performed, and the design optimization is presented. For the battery-charging control, a simple control circuit is presented and its performance is verified from the experimental results.

Analysis and experimentation of nonlinear adaptive controllers for the series resonant converter

It is the purpose of this paper to explore the problem of regulating the output voltage of a DC-to-DC series resonant power converter (SRC). These converters have highly nonlinear dynamics fed by a bipolar square signal generator whose commuting frequency is the only accessible control variable in the control architecture that the authors study. Therefore, they are confronted with the problem of controlling a nonlinear switched system by means of a modulating frequency signal. Two more complications that make this problem more challenging are that the full state is typically not available for measurement, and that the output load, usually represented by a resistance, is unknown. They show here that-for constant control input-SRCs have a unique globally attractive periodic orbit, which motivates them to consider a first harmonic approximation of the system. They then prove that this reduced model consists of a known static nonlinearity in cascade with a first order system with unknown parameters, for which adaptive output feedback solutions can be derived. They propose two different schemes, first a passivity-based controller which, as usual in these schemes, achieves asymptotically the inversion of the nonlinearity. They prove that, under some practically reasonable considerations, this control law reduces to the dissipative controller recently proposed by Stankovic et al. The second scheme directly inverts the static nonlinearity and applies standard adaptive techniques to the resulting linear system. The three controllers are implemented in an experimental setup and the results are presented as a comparative study.

Robust controller design for a series resonant converter via duty-cycle control

Robust controller design for a series resonant power converter is presented when load variation and unregulated input line voltage perturbation are taken into consideration. The perturbation of unregulated line voltage is treated as an exogenous disturbance and the load variation as a structured uncertainty of the converter. An averaged model, including disturbance and model uncertainty, is then derived. Two kinds of /spl mu/ synthesis-D-K and /spl mu/-K iteration schemes-are applied to design robust controllers to diminish the susceptibility of the regulated voltage to perturbations of load variation and unregulated line voltage. In addition, a classical controller is also designed for performance comparison. Finally, simulations and experimental results are presented to verify the feasibility of the robust control theory.

Steady-state analysis of the series resonant DC-DC converter in conjunction with loosely coupled transformer-above resonance operation

This paper presents the steady-state analysis of the series resonant DC-DC power converter (SRC) in conjunction with loosely coupled transformer (LCT) operating above resonance (f/sub s//f/sub o/>1). It is an extension of the conventional steady-state analysis of the SRC. Three operational modes other than the continuous current mode (CCM) have been identified, and the boundaries of all the operational modes are defined. Based on the well-defined operational plane, all the operational modes are analyzed. Results are given in normalized form and experimentally verified.

Reducing IGBT losses in ZCS series resonant converters

The fundamental operational parameter that controls the losses in series resonant power converters was found to be the reflected DC voltage transfer ratio. Losses which are a function of the average current (such as conduction losses of insulated gate bipolar transistors and diodes) are independent of the switching frequency. Losses which are associated with the RMS current are a function of both the reflected DC voltage ratio and the switching frequency ratio. Universal and normalized graphs, derived in this paper, can be conveniently used to assess the expected RMS and average current conduction losses under any given operational conditions. The residual switching losses in zero-current-switching series resonant power converters operating in continuous current mode can be reduced by simple current snubbers placed in the commutation circuits. The experimental results of this paper confirm the theoretical predictions and demonstrate that the turn-on snubbers can reduce switching losses by about 1.5% at a switching frequency of 65 kHz.

PWM series resonant DC-link converter with current clamping by the use of saturable core

A series resonant DC link power converter with pulsewidth modulation (PWM) capability and current peak limiting is proposed. When desired, a resonant transition creates notches in the DC link current, allowing the switches of the power converter to synchronize with external PWM strategy. For that, it requires only an additional bidirectional switch. A saturable core (SC) achieves current peak limiting of which the clamping level is automatically adjusted by the current load. Analysis and design procedure are presented for the proposed topology, which does not use any dedicated devices for startup. Simulated and experimental results corroborate the theoretical studies.

Wide-load-range resonant converter supplying the SAE J-1773 electric vehicle inductive charging interface

The recommended practice for electric vehicle battery charging using inductive coupling (SAE J-1773), published in January 1995 by the Society of Automotive Engineers, Inc., outlines values and tolerances for critical vehicle inlet parameters which must be considered when selecting a coupler driving topology. The inductive coupling vehicle inlet contains a significant discrete capacitive component in addition to low magnetizing and high leakage inductances. Driving the vehicle interface with a variable-frequency series-resonant power converter results in a four-element topology with many desirable features: unity transformer turns ratio; buck/boost voltage gain; current-source operation; monotonic power transfer characteristic over a wide load range; throttling capability down to no load; high-frequency operation; narrow modulation frequency range; use of zero-voltage-switched MOSFETs with slow integral diodes; high efficiency; inherent short-circuit protection; soft recovery of output rectifiers; and secondary d/spl nu//dt control and current waveshaping for the cable, coupler and vehicle inlet, resulting in enhanced electromagnetic compatibility. In this paper, characteristics of the topology are derived and analyzed using two methods. Firstly, the fundamental mode AC sine-wave approximation is extended to battery loads and provides a simple, yet insightful, analysis of the topology. A second method of analysis is based on the more accurate, but complex, time-based modal approach. Finally, typical experimental results verify the analysis of the topology presented in the paper.

Current-clamped, modified series resonant DC-link power converter for a general purpose induction motor drive

A new AC/AC power converter topology, in which all the switches operate in a resonant fashion to reduce switching losses, is proposed. The topology enables conduction-period control of individual current pulses, whereby pulse-width modulation (PWM) could be achieved to a fair degree of accuracy with the associated controller. The scheme implements current peak (resonant) limiting by a simple diode clamp. Improved switch utilization (voltage /spl times/ current) and reduced part-count could be cited as the merits of the circuit over the previous soft-switched current-sourced AC/AC configurations. It is experimentally verified that the output PWM controller could be used to implement constant V/F operation, and the results are presented. In-depth design criteria for the topology that gives optimized voltage stresses are presented. A charge-based, line current feed-forward, mode-controller is introduced at the input and digitally verified. Feasibility of the simultaneous control over both input power-factor and smooth input-output line currents are studied and the digital verification is presented.

Energy based closed form solution of ZCS multiresonant series-parallel converters

Under-resonant operation of an ideal multi-resonant series-parallel power converter (MRSPC) with a capacitive output filter is modeled in this paper. This operation allows zero current switching (ZCS), which is convenient for bipolar devices. The capacitive output filtering reduces the recovery effect of the rectifier diodes and is suitable for high output voltage applications. A closed-form solution is found for this power converter, based on state space analysis using energy concepts. This approach simplifies the mathematical operations and gives better physical insight of the system variables. Based on the model, the steady-state characteristics of this power converter are derived by a simulation program, which are discussed and compared with the series resonant half-bridge power converter (SRHC). The optimum power converter parameters are found for given design requirements using computerized optimization routines. Several design examples are presented and compared with SRHC. The validity of the model is verified by SPICE simulations.

Input power factor control of AC-DC series resonant DC link converter using PID operation

This paper proposes a method of power factor control for the three-phase input current of AC-DC series resonant DC link power converter systems. The proposed system has fast response, using high frequency resonance, soft switching (zero current switching), and natural commutation of thyristor switches. By implementing the PID operation strategy for switching control, the system performs reliable operation in the input power factor control, and the elimination of higher harmonic components can be achieved dramatically. The numerical and experimental results are presented in this paper.

Decoupled output voltage control of quantum series resonant converter for improved buck-boost operation

A new output voltage control technique is proposed to obtain the improved buck-boost operation of the quantum series resonant power converter (QSRC). The new nonlinear dynamic model of QSRC is first derived and the cross-coupled nonlinear term existing in the output voltage dynamics is decoupled by using control methods such as the periodic control of the boosting switch (PCBS) and the resonant current control (RCC). By applying the state-space averaging concept to the decoupled dynamics, two linear large signal averaged models are obtained for PCBS and RCC schemes. Using the proposed technique, the flux imbalance problem of the isolation transformer and the robustness of the output voltage response can be easily considered. This technique can also be widely applicable to the cascade buck-boost power converter, which can be implemented by inserting a boosting switch between the output filter inductor and the ripple capacitor of the forward power converter. The validity of the proposed scheme is confirmed by the computer simulations and the experiments.

Super-resonant converter with switched resonant inductor with PFM-PWM control

The efficiency of the series-resonant power converters is proved to increase with the improvement of the current form factor of the resonant current. The application of "soft-switching" reduces the switching losses. The maximum value for the pulse frequency in a super-resonant converter is limited by the introduction of a method of pulse width modulation. To improve the current form factor a second inductance is placed in the output side of the converter. This inductance is alternately included in the resonant circuit. The paper offers graphical presentation of the characteristics made to select the choice of the best suitable relationship between the resonant and output inductances and to support the design. The role of the parasitic elements of a transformer is specified.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

A multiphase series-resonant converter with a new topology and a reduced number of thyristors

Multiphase series resonant (SR) power converters provide a flexible way to transform power between a utility grid and a multiphase load or source. The current implementations all suffer from a high component count, which makes the use of these power converters unattractive from an economical point of view. A new topology for multiphase SR power converters has been proposed in the literature in a simulation context. This topology uses half the number of power semiconductors compared to the existing multiphase SR power converters. The present paper addresses the implementation of the new topology in a prototype power converter. The old and new topologies are presented. The operation of the new topology is explained. In the new topology the resonant circuit is grounded at one side, which compared to the old topology imposes a restriction on the operation. The paper shows both simulation data and measured waveforms. It is explained that the economical gain due to the reduction in component count is offset by a lower power rating. The paper finishes with conclusions and acknowledgments.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

An ultrasonic series resonant converter with integrated L-C-T

The concept of an integrated structure for the capacitor, inductor and transformer of the series resonant power converter is presented. It is shown that the necessary capacitance can be achieved by using a bifilar primary and the leakage inductance of the transformer replaces the physical inductor. By integrating three components into one it would be possible to save space, mass, volume and cost.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>