Resonant Converter Operating Research Articles

Averaged large-signal model of quantum series-parallelresonant converter

An averaged large-signal model of the quantum series-parallel resonant converter operating in continuous conduction mode is developed and verified using cycle-by-cycle simulations. The model can be used to both derive simple design tools under steady-state conditions and predict large-signal transient responses by using any modern circuit simulator.

Resonant converter in high power factor, high voltage DC applications

The performance of the high-frequency high-order series resonant converter operating in high power factor mode is presented. The pulsating DC voltage obtained from a single phase uncontrolled diode bridge rectifier is applied to the high-frequency full-bridge configuration of the resonant converter. Such an AC–DC converter operates at a high power factor without any active control of the input line current. High frequency (HF) transformer nonidealities (i.e. leakage inductance and magnetising inductance) are incorporated for analysis of the basic operation of circuit. This configuration is well-suited for higher output voltage applications such as high voltage DC power supplies. The lower order harmonics present in input line current are minimised by removing the gating pulses to the HF switches for a predetermined duration known as modulating window. A useful analytical technique, based on classical complex AC circuit analysis is suggested for designing the high-order series resonant tank circuit. The output voltage is regulated by independently using variable frequency control and duty ratio control. This AC–DC converter is simulated using TUTSIM and PSPICE packages, and an experimental prototype unit is developed using high frequency switches (MOSFETs).

High power factor operation of resonant converters on the utility line

Operation and characteristics of resonant converters on the utility line are presented. Series-parallel (LCC-type) resonant converter operating with discontinuous current mode and continuous current mode (variable frequency control as well as fixed-frequency) are considered. Design examples are presented. SPICE simulation and experimental results obtained for the designed converters (rated at 150 W) are presented to verify the theory. It is shown that high line power factor (>0.95) and line current total harmonic distortion (THD) of <25% are obtained for the LCC-type converter for a wide load range (from full load to 10% rated load) without any active control, and the switch peak current decreases with the load current. With active line current control, low distortion and zero voltage switching for the entire cycle are realized.

Dynamic analysis of LCC-type parallel resonant converter operating in discontinuous current mode

A discrete time-domain model for the LCC-type parallel resonant converter, operating in discontinuous current mode (DCM), is derived. This model, which makes use of some practical approximations, simplifies the calculations, reduces the computer simulation time and is adequate to predict some of the basic design constraints (peak component stresses, etc.) which are governed by the dynamics of the converter during large-signal transients. PROMATLAB software was used to solve the discrete-model equations on the computer. Theoretical results are verified by SPICE simulation and experiments. An approximate small-signal model is also derived and used to predict the small-signal behaviour of the converter.

Small signal analysis of the LCC-type parallel resonant converter

In this paper, the small signal analysis of the LCC-type parallel resonant converter (LCC-PRC) operating in the continuous conduction mode is given. This analysis is based on both the state-plane diagram, which has been successfully used to obtain the steady state response for resonant converters, and the Taylor series expansion. Applying perturbation directly to the steady state trajectory, a discrete small signal model for the converter can be derived in terns of the input voltage, switching frequency, and the converter state variables. Based on this analysis, closed-loop form solutions for the input-to-output and control-to-output transfer functions are derived. It is shown that the theoretical and computer simulation results are in full agreement.

State-plane approach for the analysis of half-bridge parallel resonant converters

Generalised state-plane analysis for a half-bridge parallel resonant converter (PRC) operating in continuous conduction mode is presented. It is shown that a PRC circuit of any order can be analysed in terms of simple two-dimensional state-plane diagrams, without having to use any sinusoidal approximation. The approach presented makes use of the state-variable transformation technique previously used for the analysis of second- and third-order resonant converters. This method is applied to a specific example of a sixth-order parallel resonant converter operated in the continuous conduction mode.

Dynamic analysis of LLCC parallel resonant converter under pulse-width modulation control

The large and small signal dynamic analysis of LLCC-type parallel resonant converter operating in continous-conduction mode under fixed frequency, variable duty-ratio (pulse-width modulation) control is presented in this paper. The nonlinear and small-signal equations of the converter including the supply and output rectifiers are derived. The influence of the converter operation on the supply input power factor and how the input rectifier affects the small-signal dynamics of the converter are discussed.

Generalized approach to the small signal modelling of DC-to-DC resonant converters

A generalized small-signal analysis approach that is based on both the Taylor's series expansion and the state-plane diagram is presented. A generalized discrete small-signal model for a double-ended DC-to-DC resonant converter operating in the continuous conduction mode is also given. Based on the model derived, the frequency responses for two transfer functions, namely, the line-to-output and the control-to-output transfer functions, are obtained. The technique is verified by applying it to the conventional series resonant converter whose small-signal analysis is known. >

Analysis, design, and optimization of a secondary-side resonant converter operating in the discontinuous capacitor voltage mode

A high-frequency link parallel resonant DC/DC power converter (PRC) operating in the lagging power factor mode with the resonating capacitor on the secondary side of the high-frequency (HF) transformer is analyzed for operation in the discontinuous capacitor voltage mode (DCVM) using a state-space approach. Converter equations are solved for operation under steady-state condition. Based on the analysis, design curves are obtained for DCVM operation. A method of obtaining the optimum operating point under certain constraints for DCVM operation is developed and is used to develop a simple design procedure. Experimental results obtained with a MOSFET-based 1 kW PRC are presented to support the theory. >

Frequency response for the conventional parallel resonant converter based on the state-plane diagram

The small-signal analysis of the conventional parallel resonant converter (PRC) operating in the continuous conduction mode is given. This analysis is based on the state-plane approach that has been successfully used to obtain the steady-state response for resonant converters. Applying perturbation directly to the steady-state trajectory, a discrete small-signal model for the converter can be derived in terms of the input voltage, switching frequency, and the converter state variables. Furthermore, this method can be applied to resonant converters in general, regardless of the order of their resonant tanks. Based on the derived closed-form solution, the frequency responses of input-to-output and control-to-output transfer functions are obtained. Computer simulation and experimental results are reported.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

Analysis of series-parallel resonant converter

A frequency-domain steady-state analysis is given for a series-parallel resonant converter (SPRC) operating in the continuous conduction mode (CCM) using Fourier series techniques. Equations for performance parameters are derived under steady-state conditions to provide simple design tools. The topology of the SPRC combines the advantageous properties of both the series resonant converter (SRC) and the parallel resonant converter (PRC). The key results of the work are: a novel half-wave rectifier SPRC, conditions for obtaining high part-load efficiency; and several boundary frequencies and limiting conditions such as the capacitive/inductive load boundary and open-circuit and short-circuit cases. Experimental results measured for an 80-W converter above the resonance at different load resistances and input voltages show excellent agreement with the theoretical performance predicted by the equations. >

Commutation Modes in Resonant Converters Control and Safety In DC-DC Conversion

SummaryIn this paper the authors present the two different soft commutation modes for DC-DC power conversion and resonant systems.Spontaneous commutations become possible in a resonant converter.Two basic function are studied: thyristor for a zero-current-switching mode(ZCS)and dual-thyristor for a zero-voltage switching mode(ZVS).The dual-thyristor for a voltage inverter structure whereas the thyristor mode is usually used in current inverters.For this last mode a control strategy is proposed which ensures safe operation in voltage inverter.Then, this control is applied on a series resonant DC-DC converter operating in ZCS mode.In that case the switching frequency is below the resonant frequency.The theoretical study is carried out with snubbers(sreies inductance)which don’t disturb the normal operation for all nthe loads.

Theoretical and experimental studies of the LCC-type parallel resonant converter

Using the state-plane approach, the steady-state analysis and design of a high-frequency LCC-type parallel resonant converter (LCC PRC) operating in the continuous conduction mode are carried out. On the basis of this analysis, a set of steady-state characteristic curves for the LCC PRC is plotted. Various design curves for component value selection and device ratings are also presented. A simple design procedure is given, and a design example for a 150 W, 140 kHz multioutput LCC PRC power supply is presented for illustrative purposes. A prototype unit has been built and verifies the theoretical results.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

State-plane analysis of zero-voltage-switching resonant DC/DC converters

The state-plane analysis technique is established for the zero-voltage-switching resonant DC/DC power converter family of topologies, namely the buck, boost, buck-boost, Cuk, sepic, and dual-sepic converters. The state plane provides a compression of information, which allows the designer to examine the nonlinear dynamics of resonant converter operation. Utilizing the state plane, modes of resonant converter operation are examined. Expressions are derived for the switching frequencies at the boundaries between these modes and at the boundary of energy conversion.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>