Design of robust controllers for resonant DC/DC converters (original) (raw)
2010 1st Power Electronic & Drive Systems & Technologies Conference (PEDSTC), 2010
Robust performance controller design for duty-cycle controlled series resonant converter (SRC) is proposed in this paper. The uncertainties of the converter are analyzed with load variation and power circuit components tolerances are taken into consideration. Additionally, a nominal performance (NP) H ∞ controller is designed. Closed-loop system is simulated with Orcad and simulation results of robust controller are compared with H ∞ nominal performance controller. Although H ∞ nominal performance controller has better performance for nominal plant, the robust performance controller is advantageous in dealing with uncertainties.
Analysis and experimentation of nonlinear adaptive controllers for the series resonant converter
IEEE Transactions on Power Electronics, 2000
It is the purpose of this paper to explore the problem of regulating the output voltage of a dc-to-dc series resonant 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 we study. Therefore, we 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. We show here that-for constant control input-SRC's have a unique globally attractive periodic orbit, which motivates us to consider a first harmonic approximation of the system. We 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. We propose two different schemes, first a passivity-based controller which, as usual in these schemes, achieves asymptotically the inversion of the nonlinearity. We prove that, under some practically reasonable considerations, this control law reduces to the dissipative controller recently proposed by Stanković 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.
A novel hybrid modeling of DC-DC series resonant converters
IECON 2013 - 39th Annual Conference of the IEEE Industrial Electronics Society, 2013
A dc-dc resonant converter has the advantage of overcoming switching losses and electromagnetic interference which are the main limitations of high frequency power converters. Nevertheless, the modeling and stability analysis of dc-dc resonant converters are considerably more complex than pulsewidth modulation counterparts. The conventional averaged linearized model of the resonant converter has limitations due to averaging and linearization. First of all, the linearized model has large modeling error in presence of large variations of reference voltage and input voltage. Furthermore, Converging area for stabilizing controllers is smaller in the averaged model. In order to overcome these limitations, this paper presents a novel framework for modeling of dc-dc resonant converters. As dc-dc resonant converters are naturally switched systems with affine subsystems, a piecewise affine model is derived directly from the converter model. The new model is based on analysis of the resonant converter on state plane trajectories. It is also suitable for precise simulation and high performance controller design of resonant converters. In addition, a stability analysis theorem is provided for the proposed model. The simulation and experimental results on a dc-dc series resonant converter show the effectiveness of this modeling approach.
Nonlinear Modeling and Stability Analysis of Resonant DC-DC Converters
Resonant dc-dc converters have found increasing application in industry in recent times. Yet, the methods of dynamical analysis and parameter design for this kind of system are not well developed. The averaging method cannot be used in such converters as the small-ripple assumption does not hold. The sampled-data model, which seeks to obtain a closed form expression of the state at a clock instant in terms of that at the previous clock instant, also becomes unwieldy for converters with many topological modesa condition prevailing in all resonant converters. In this study the authors show that the Filippov method can be effectively applied for accurate s-domain small signal analysis as well as time domain stability analysis by locating the stability boundaries in the paramater space for such systems. The authors apply this method to three classes of resonant convertersthe switch resonant converter, the resonant transition converter and the load resonant converterand present the mechanisms by which these converters may lose stability as the parameters are varied. The theoretical results corresponding to the resonant transition converter are validated experimentally.
ieeexplore.ieee.org
This paper reports to determine the controller parameters for the stable operation of one member of a load resonant dc-dc converters by a newly developed tool. The study is confined to the series-parallel topology with capacitive output filter. The constant frequency phase shift modulation technique is employed with proportional-integral controller in the output voltage regulation. The analysis complexity is very high due to fact that nine topological modes and four switching surfaces give rise to several operation modes. In addition to the determination of the controller parameters for stable operation, different mechanisms of instability of period-1 limit cycle are predicted from the design curve which constitute an important help for any designer.
Stability analysis of a feedback-controlled resonant DC-DC converter
This paper reports on the stability analysis of one member of a dual-channel resonant dc-dc converter family. The study is confined to the buck configuration in symmetrical operation. The output voltage of the converter is controlled by a closed loop applying constant-frequency pulsewidth modulation. The dynamic analysis reveals that a bifurcation cascade develops as a result of increasing the loop gain. The trajectory of the variablestructure piecewise-linear nonlinear system pierces through the Poincaré plane at the fixed point in state space when the loop gain is small. For stability criterion the positions of the characteristic multipliers of the Jacobian matrix belonging to the Poincaré Map Function defined around the fixed point located in the Poincaré Plane is applied. In addition to the stability analysis, a bifurcation diagram is developed showing the four possible states of the feedback loop: the periodic, the quasi-periodic, the subharmonic, and the chaotic states. Simulation and test results verify the theory. Index Terms-Resonant dc-dc converter, stability. Octavian Dranga was born in Oradea, Romania, in 1971. He received the B.Sc., M.Sc., and Ph.D degrees from the
Control of resonant converters using the LQG/LTR method
PESC `92 Record. 23rd Annual IEEE Power Electronics Specialists Conference, 1992
In order to control resonant converters, it is necessary to design a robust controller. This has been achieved with classical methods by means of empirical rules. This paper proposes a method based on robust optimal control. This method is more powerful and systematic. The design procedure and the inprovement in th e dynamics response is shown in an aplication to a ZCS parallel half bridge resonant converter.