Buck-boost Power Converter Research Articles

Power Management of Wideband Code Division Multiple Access RF Power Amplifiers With Antenna Mismatch

This paper focuses on a combination of adaptive power supply and adaptive impedance tuning for WCDMA RF power amplifiers (RFPA) in wireless handsets in order to improve the system efficiency under different transmit power levels and antenna mismatch. The adaptive power supply is a noninverting buck-boost power converter. It is shown that precise output voltage positioning and low output voltage ripple over a wide output voltage range, including buck, boost, and buck/boost transition modes, can be accomplished using ?-? modulation in combination with a small, low-resolution DPWM core. A two-mode digital controller is presented, in which the compensator parameters are changed upon buck/boost mode transitions in order to improve closed-loop dynamic performance. Furthermore, improvements in system efficiency are demonstrated using this adaptive power supply combined with an adaptive RF impedance tuner between the RFPA and the antenna. The results are verified on an experimental test bed that consists of a discrete RFPA, impedance tuner, a prototype 0.5 ?m CMOS power stage IC that integrates power MOSFETs, drivers and deadtime control logic, and a digital power management controller implemented on an FPGA.

Experimental confirmation of frequency correlation for bifurcation in current-mode controlled buck-boost converters

Frequency scaling in pulse-width modulated buck-boost power converters can be used to predict the first bifurcation point at various frequency operations. This letter first derives novel frequency correlation for the power converter. This is then examined by experimental results at high-frequency operation.

Sliding mode control of boost and buck‐boost power converters using the dynamic sliding manifold

AbstractNon‐minimum phase tracking control is studied for boost and buck‐boost power converters. A sliding mode control algorithm is developed to track directly a causal voltage tracking profile given by an exogenous system. The approximate causal output non‐minimum phase asymptotic tracking in non‐linear boost and buck‐boost power converters is addressed via sliding mode control using a dynamic sliding manifold (DSM). Use of DSM allows the stabilization of the internal dynamics when the output tracking error tends asymptotically to zero in the sliding mode. The sliding mode controller with DSM links features of conventional sliding mode control (insensitivity to matched non‐linearities and disturbances) and a conventional dynamic compensator (accommodation to unmatched disturbances). Numerical examples demonstrate the effectiveness of the sliding mode controller even for a known time‐varying load. Copyright © 2003 John Wiley & Sons, Ltd.

Sliding mode control of boost and buck-boost power converters using method of stable system centre

Nonminimum phase tracking control is studied for boost and buck-boost power converters. The sliding mode controller is designed to track directly a causal voltage tracking profile given by an exogenous system. The nonminimum phase output tracking problem is reduced to a state tracking problem. Bounded state tracking profiles are generated by equations of stable system centre. Numerical examples demonstrate the effectiveness of the sliding mode control design.

ANN based peak power tracking for PV supplied DC motors

This paper presents an application of an Artificial Neural Network (ANN) for the identification of the optimal operating point of a PV supplied separately excited dc motor driving two different load torques. A gradient descent algorithm is used to train the ANN controller for the identification of the maximum power point of the Solar Cell Array (SCA) and gross mechanical energy operation of the combined system. The algorithm is developed based on matching of the SCA to the motor load through a buck-boost power converter so that the combined system can operate at the optimum point. The input parameter to the neural network is solar insolation and the output parameter is the converter chopping ratio corresponding to the maximum power output of the SCA or gross mechanical energy output of the combined PV system. The converter chopping ratios at different solar insolations are obtained from the ANN controller for two different load torques and are compared with computed values.

Analysis and design of a high power factor, single-stage electronic dimming ballast

This paper presents the analysis, design and practical consideration of a single-stage electronic dimming ballast with unity power factor. The power stage of the ballast is derived from combining a buck-boost power converter and a half-bridge series-resonant parallel-loaded inverter (SRPLI). With the plasma model of the lamp, the analysis of the ballast is carried out, from which the key equations used for dimming control are derived. Starting performance and dimming consideration are also addressed in the paper. In this dimming ballast, both pulsewidth modulation (PWM) and variable-frequency control strategies are employed. The discussed ballast with the controls can save a controller and a switch driver, reduce size and cost, and possibly increase system reliability over conventional two-stage systems in the applications with moderate power level. Simulated and experimental results of the ballast for an OSRAM T8 32-W lamp are used to verify the discussion.

A new control strategy to achieve sinusoidal line current in a cascade buck-boost converter

This work presents a detailed theoretical analysis and experimental results of a novel means of obtaining sinusoidal input current and unity power factor (UPF) via a cascade buck-boost power converter. Using the new configuration, sinusoidal line current in phase with the bus voltage is achieved, thanks to a new and simple to implement control strategy. Comparison between the input and output voltages is used to select the instantaneous operating mode of the converter. Offline references are calculated and stored in two EPROM circuits and then compared to measured currents to generate the gating signals of the appropriate switches. Complete theoretical analysis, simulation results and experimental data on a 500 W power converter are presented, to demonstrate the superiority of the new control strategy. Low order harmonics in the input current are eliminated and the input power factor is found to be over 0.99.

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.

Computer Simulations of Optimum Boost and Buck-Boost Converters

The development of mathematical models suitable for minimum weight boost and buck-boost converter designs are presented. The facility of an augumented Lagrangian (ALAG) multiplier-based nonlinear programming technique is demonstrated for minimum weight design optimizations of boost and buck-boost power converters. ALAG-based computer simulation results for those two minimum weight designs are discussed. Certain important features of ALAG are presented in the framework of a comprehensive design example for boost and buck-boost power converter design optimization. The study provides refreshing design insight of power converters and presents such information as weight and loss profiles of various semiconductor components and magnetics as a function of the switching frequency.