A noninverting buck-boost converter with reduced components using a microcontroller

With the advent of battery-powered portable devices and mandatory adoption of power factor correction, noninverting buck-boost converters are garnering lots of attention. Conventional two-switch or four-switch noninverting buck-boost converters choose their operation modes by measuring input and output voltage magnitude. The criterion for the selection of the operation mode can cause higher output voltage transients in the neighborhood, where input and output are close to each other. For the mode selection, due to the voltage drops raised by the parasitic components, it is not enough just to compare the magnitude of input and output voltages. In addition, the difference in the minimum and maximum effective duty cycles between controller output and switching device yields discontinuity at the instant of mode change. Moreover, the different properties of output voltage versus a given duty cycle of buck and boost operating modes contribute to the output voltage transients. In this paper, the effect of the discontinuity due to the effective duty cycle derived from the device switching time at the mode change is analyzed. A technique to compensate the output voltage transient due to this discontinuity is proposed. In order to attain additional mitigation of output transients and a linear input/output voltage characteristic in buck and boost modes, the linearization of DC gain of the large-signal model in boost operation is analyzed as well. Analytical, simulation, and experimental results are presented to validate the proposed theory.

This paper focuses on the non-inverting buck- boost converter operated as either buck or boost converter. It is shown that a pulse-width modulation (PWM) discontinuity around buck/boost mode transition can result in substantial increases in output voltage ripple. The effect of the PWM nonlinearity is studied using periodic steady state analysis to quantify the worst case ripple voltage in terms of design parameters. Furthermore, a bifurcation analysis shows that the PWM discontinuity leads to quasi- periodic route to chaos, which results in erratic operation around the buck/boost mode transition. The increased ripple is a very significant problem when the converter is used as a power supply for an RF power amplifier, as is the case in WCDMA handsets. An approach is proposed to remove the discontinuity which results in reduced output voltage ripple, at the expense of reduced efficiency, as demonstrated on an experimental prototype.

In this paper, a non-inverting buck-boost derived hybrid converter (NIBBDHC) is proposed. It is derived from conventional two switch non-inverting buck-boost converter topology. Here, a parallel switch in conventional two-switch non-inverting buck-boost converter has replaced by a bridge type voltage source converter (VSC). Thus, the proposed converter topology can give both DC and AC outputs simultaneously and has fewer number of semiconductor switches. The presented topology has two major features. First, it can supply both higher and lower voltages than input voltage as per the requirement without inversion. Secondly, the shoot-through problem of conventional inverter can be well utilized for the operation of the converter. The brief explanation of converter operation along with steady state analysis is presented. Further, modification is carried out in unipolar sinusoidal pulse width modulation technique as a control scheme for the operation of converter. Finally, results are validated through simulations.

Many electronic power distribution systems have strong needs for highly efficient AC-DC conversion that can be satisfied by using a buck-boost converter at the core of the power factor correction (PFC) stage. These converters can regulate the input voltage in a wide range with reduced efforts compared to other solutions. As a result, buck-boost converters could potentially improve the efficiency in applications requiring DC voltages lower than the peak grid voltage. This paper compares SEPIC, noninverting, and versatile buck-boost converters as PFC single-phase rectifiers. The converters are designed for an output voltage of 200 V and an rms input voltage of 220 V at 3.2 kW. The PFC uses an inner discrete-time predictive current control loop with an output voltage regulator based on a sensorless strategy. A PLECS thermal simulation is performed to obtain the power conversion efficiency results for the buck-boost converters considered. Thermal simulations show that the versatile buck-boost (VBB) converter, currently unexplored for this application, can provide higher power conversion efficiency than SEPIC and non-inverting buck-boost converters. Finally, a hardware-in-the-loop (HIL) real-time simulation for the VBB converter is performed using a PLECS RT Box 1 device. At the same time, the proposed controller is built and then flashed to a low-cost digital signal controller (DSC), which corresponds to the Texas Instruments LAUNCHXL-F28069M evaluation board. The HIL real-time results verify the correctness of the theoretical analysis and the effectiveness of the proposed architecture to operate with high power conversion efficiency and to regulate the DC output voltage without sensing it while the sinusoidal input current is perfectly in-phase with the grid voltage.

Multimode power processing interface for fuel cell range extender in battery powered vehicle

In this paper, a modified boost converter topology for electric vehicle charging from a photovoltaic source is proposed. The proposed topology offers higher voltage gain and lower ripple content over the conventional boost converter. Investigations into the characteristics of lithium battery load, selection of the photovoltaic panel rating are discussed. Simulation studies on the performance of conventional and modified boost converter are performed with a resistive load using MATLAB/ Simulink. Experimental results validate the simulation studies. The proposed topology has a single switch and results indicate higher voltage gain with a 22 V input stepped up to 51 V and higher output voltage with a 48 % moderate duty cycle.

Analysis, control and design of a non-inverting buck-boost converter: A bump-less two-level T–S fuzzy PI control

This paper presents a new single phase front-end ac-dc bridgeless power factor correction (PFC) rectifier topology. The proposed converter achieves a high efficiency over a wide range of input and output voltages, a high power factor, low line current harmonics and both step up and step down voltage conversions. This topology is based on a non-inverting buck-boost (Zeta) converter. In this approach, the input diode bridge is removed and a maximum of one diode conducts in a complete switching period. This reduces the conduction losses and the thermal stresses on the switches when compare to existing PFC topologies. Inherent power factor correction is achieved by operating the converter in the discontinuous conduction mode (DCM) which leads to a simplified control circuit. The characteristics of the proposed design, principles of operation, steady state operation analysis, and control structure are described in this paper. An experimental prototype has been built to demonstrate the feasibility of the new converter. Simulation and experimental results are provided to verify the improved power quality at the AC mains and the lower conduction losses of the converter.

The existence of operational dead zone during mode switching in noninverting buck-boost converter results in oscillation of the output voltage and instability of the system during high power operation. The mechanism and effect of the operational dead zone are analyzed, the conditions that need to be met when eliminating the operational dead zone are researched, and a multimode smooth switching control strategy which can completely eliminate the operational dead zone is proposed. The converter works with three operating modes, the method of theoretical analysis combined with experimental correction is used to set the mode switching parameters, to ensure that the actual voltage gains of the converter on both sides of the mode switching points are equal. A single-degree-of-freedom buck-boost mode is designed to replace the pass-through mode to maintain the converter's stable output. And the converter's operating power level and overall power transmission efficiency can be improved, when the control parameters are designed to reduce the interval length of the boost mode and the single-degree-of-freedom buck-boost mode. Finally, a 700-W experimental prototype is built to verify the effectiveness of the proposed solution.

11 - Adaptive control for second-order DC–DC converters: PBC approach

This paper presents the verification and implementation of non-inverting buck-boost converter in the application of energy-harvesting battery charger which is widely used in multiple power source embedded system. Simplified models for PV and rechargeable battery have been used for theoretical analyzing. Buck and boost topologies have been analyzed to obtain the MPP (Maximum Power Point) under different supply voltages and several Power-Duty cycle curves have been obtained. The combination of the curves verifies the feasibility of the usage of non-inverting buck-boost converter in such application. Hardware circuit is also constructed and the experimental results match the theoretical data precisely.

This work is aimed at making an objective comparison of the mode transition techniques reported for the non-isolated bidirectional dc-dc converters (BDCs) such as synchronous buck converter, non-inverting buck-boost converter, dual active bridge (DAB), etc. The analysis is carried out by creating a mathematical models for these transition techniques. A comparison has been made based on the type of transition technique, time requirement, and other important factors to achieve a smooth transient response during start-up and mode transition (i.e., during reversal of power flow) operations. The analysis of the transition techniques has been validated through PSIM simulations as well as experimentation for 132 V and 330 V voltages at the input and output ports for 1.5 kW of output power.

This paper studies boundary control for a multiple-input buck-boost (MIBB) converter topology with equal voltages at each input leg. In addition to not requiring different input voltages as in previously suggested MIBB converters, when input voltages are equal the proposed controller eliminate the need for forward-conducting bidirectional-blocking switches (FCBBs) also present in previous MIBB topologies. The prescribed controller makes the closed loop MIBB system to behave as a single-input buck-boost converter so that a solution to in the sense of Filippov can be defined in reflective mode. Large-signal asymptotic stability of the desired operating point is subsequently established using Lyapunov's direct method. The state-dependent switching strategy presented ensures that the system avoids certain limitations that occur when multiple-input converters that operate based on switching period-sharing. These restrictions include different input voltages, and limited number of input legs. A lower parts count and better efficiency may then be achieved. Robustness and other attributes of boundary control make the proposed strategy favorable. Both pros and cons of the proposed scheme are discussed and design recommendations are given. The analysis is verified by simulations and an experimental setup with four input legs.

Patients with heart failure may utilize Left Ventricular Assist Devices (LVADs), which are critical life-support equipment that enhance cardiac function. The efficacy and safety of these devices are primarily contingent upon the efficiency, reliability, and precision of their Brushless DC (BLDC) motor drives. This paper presents a methodology for designing a wireless power transfer (WPT) system to power a left ventricular assist device (LVAD), using a non-inverting buck-boost converter and a PI controller to regulate blood flow rate by controlling the motor speed. Particle Swarm Optimization (PSO) Algorithm is employed to optimize the controller parameters for a PI control scheme. The reengineered controller ensures minimal speed ripple, enhanced torque responsiveness, and superior efficiency in both steady-state and transient conditions. The simulation outcomes in MATLAB/Simulink indicate that this procedure outperforms conventional tuning methods. It enhances system efficiency, reduces strain on components, and increases reliability for prolonged LVAD use. A maximum transmission efficiency of 76% was achieved at a 30 mm transmit-receive coil spacing, with a good dynamic response of (0.32-0.54)% overshoot, (1.8-2.34)% undershoot, and a rise time of (68-76) ms.

This manuscript details a design method for a 500kW solar power based microgrid system for space applications. The design method utilizes multi-objective optimization with the Genetic Algorithm considering four parameters that characterize solar power based microgrids (battery voltage, PV maximum power, PV maximum power point voltage, and number of panels per string). The final optimization metric is the ratio of daily average deliverable power to total system mass (W/kg) metric. The microgrid system is composed of a number of modular DC-DC micro-converters, of which four topologies (buck, boost, buck-boost and non-inverting buck-boost) are evaluated and compared. The non-inverting buck-boost converter is determined to be the best candidate, and the optimal system characteristics are provided and analyzed. The final system design achieves a specific power of 35.56W/kg, with optimized result of 743.7V battery voltage, 439.5W PV maximum power, 182.7V PV maximum voltage, and three panels per string. Based on the optimizations results, a prototype is designed, tested, and analyzed in terms of efficiency and low temperature reliability. The converter achieved a peak efficiency of 98.4%, a power density of 3.54W/cm3, a specific power of 3.76W/g, and operated for over 267 hours of Ll-minute low temperature cycles from 0°C to -140°C.