State-plane Approach Research Articles

Unified design for ZVT PWM converters with resonant auxiliary circuit

Operation modes of zero-voltage transition (ZVT) PWM converters with resonant auxiliary circuit (RAC) are identified and analysed by means of a common topology. A novel state-plane approach is used to determine the soft-switching boundary for this sort of converter. A unified design criterion, based on the analytical definition of the soft-switching boundary, is described in detail. By means of the proposed criterion the time spent on repetitive numerical simulation of a given topology to define its design guidelines based on a set of particular features can be significantly reduced. The theoretical analysis is confirmed by means of experimental results obtained from ZVT-PWM boost converters, which operate at 1 kW, 100 kHz.

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.

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>

Steady-state analysis of the parallel resonant converter with LLCC-type commutation network

A novel converter topology known as LLCC-type parallel resonant converter (PRC-LLCC), in which the tank circuit consists of two inductors and two capacitors, is introduced. Using the state-plane approach, the steady-state analysis of the PRC-LLCC operating in the continuous conduction model is carried out. It is shown that by using the state variable transformation technique the steady-state response of the converter can be represented by two state-plane diagrams. Using these diagrams and the circuit equations, a set of control characteristic curves which are useful for converter design is derived. Based on these curves, a design procedure along with a specific design example is given. The correctness of the analysis results is verified via computer simulations.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

State plane approach to frequency response of resonant convertors

The steady state response of a resonant convertor can be represented graphically by the state plane diagram. On using the perturbation method on the steady state trajectory, a discrete small signal model for the convertor can be derived from the input voltage, controlled switching frequency and state variable perturbations. The conventional series resonant convertor is used as an example to demonstrate an analytical approach. However, this method of analysis can be applied to resonant convertors in general. From the small signal model derived, the frequency response of the convertor can be calculated.

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>