A Compensation Technique for Smooth Transitions in a Noninverting Buck–Boost Converter

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.

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.

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 simple method for the microcontroller implementation of a noninverting buck-boost converter. The converter requires two switches, but only one set of controls. As compared to a cascaded buck converter/boost converter topology, the noninverting buck-boost converter requires one less capacitor and inductor. The system operates as a buck converter for duty cycles between 0-50% in the microcontroller, and as a boost converter (up to a gain of twice the input voltage) for duty cycles between 50-100%. The system is therefore also advantageous because the microcontroller algorithm prevents a dead short from occurring during operation in the boost converter mode. Experimental and PSpice results prove that both buck and boost operation are possible using this topology. The effect of the load resistance on the results is discussed.

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.

Based on the hierarchical control structure in islanded Micro-Grid (MG) systems, the coupling/tradeoff effects in different levels are analyzed in details. In the primary level, analyses of the coupling effects among droop control gains, line impedance differences, output reactive power and voltage magnitudes are provided specifically. In the secondary level, the tradeoffs between accurate reactive power sharing and voltage magnitudes regulation are further detailed. The analysis results can provide a guideline for the design of MG structure and its control parameters. In addition, novel containment-based controller is proposed to control the voltage into a reasonable range which is the first time to apply this algorithm in MG. Furthermore, dynamic-consensus-based controller is used to guarantee accurate reactive power sharing. The combination of controllers offers a coordinated distributed operation and enhanced system performance. Finally, experimental results are shown to validate the effectiveness of the proposed method.

This paper aims at obtaining fixed output voltage of frequency 50 Hz to the load by a Self Excited Induction Generator (SEIG) employed in Wind Energy Conversion System (WECS). The output voltage of a SEIG is a function of wind turbine’s speed, which varies with wind velocity. Due to the variation in shaft speed of the wind turbine, the output voltage and frequency of Doubly Fed Induction Generator (DFIG) will vary. In this paper, a new WECS is proposed in which the conventional PWM AC/ DC/ AC converter is replaced by a Matrix Converter (MC) topology and the DFIG machine is replaced by a low cost Squirrel Cage Induction Generator. MC eliminates bulky DC link capacitor, provides bi-directional power flow capability, independent control on the output voltage magnitude, frequency and phase angle as well as the input power factor. Space Vector Pulse Width Modulation (SVPWM) technique is used for controlling MC in such a way that output load voltage and frequency is kept constant for all wind velocities. The SVPWM technique provides higher voltage transfer ratio without lower order harmonics. SVPWM is digitally implemented using DSP processor (TMS320 F2407A). Switching times are pre-calculated offline. Semi soft commutation procedure for safe switching control of MC switches is also presented.

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.

A single-inductor four-switch non-inverting buck-boost dc-dc converter was designed. Compared to other conventional buck-boost typologies, the presented converter reduces the number of external passive components and chip/PCB area. The chip was implemented by using the TSMC 0.35um 3.3V/5V 2P4M polycide CMOS process. The input voltage range of the presented converter covers the full output voltage range of a Li-ion battery, its output voltage is 3.3V, and its maximal load current is 300 mA. The die area of the chip is 1.38 ×1.80 mm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> , packed with a 40 S/B package.

Objective: To design the trapezoidal pulse width modulation (TPWM) technique in order to reduce the total harmonic distortions at the output of the converter particularly the AC-AC frequency converter. Methods/Analysis: The proposed scheme of modulation technique is used as a modification as compared to that of an unmodulated converter. Two different parameters, namely frequency of the output from the converter and the frequency of the carrier wave, were varied to obtain the harmonic profile of the output voltage of the converter. Results were verified using MATLAB/SIMULINK software environment. Findings: The generalized 1 ϕ AC-AC frequency converter discussed, can be operated both as cyclo-converter (step down) and cyclo-inverter (step up). The output from these converters contain high THD values at the output. The techniques of filtering cannot be used due to numerous reasons. So the TPWM technique is implemented on the frequency converters. The least THD obtain was 0.983 % at 250 Hz for a step up configuration and THD was about 0.8019 % at 25 Hz in case of a step down converter. In addition to varying the output frequency, carrier frequency, f c , of the carrier wave was also varied to check the THD response of the converter and it was least at 1 kHz of about 0.9316 %. In all case, magnitude of output voltage was on higher side of fundamental frequency component. Novelty/Improvement: Simulation results shows that the THD values have been reduced with the application of modulation techniques as compared to that of the output from an unmodulated converter which can help in various application requiring AC-AC converters. Keywords: Cyclo-Converter, Cyclo-Inverter, Matrix Converter, Total harmonic distortion (THD), Trapezoidal Pulse Width Modulation Technique (TPWM)

This paper introduces a new current-programmed controller for non-inverting buck-boost converters. The controller facilitates tight voltage regulation and excellent transient convergence, all carried out through a simple CPM controller hardware. Steady-state operation for the full range of conversion ratios is supported with seamless transitions between modes and improved efficiency and ripple characteristics around unity conversion gain. In case of a load transient, an optimized boundary control scheme achieves near-optimal recovery, with programmable constrains for the voltage deviation and inductor current, covering the entire range of conversion ratios. The operation of the controller is experimentally verified on a 2-15V input to 3.3V output, non-inverting buck-boost converter, demonstrating significant improvement in steady-state around unity gain as well as fast convergence for load transients with programmable constraints for the output voltage deviation and inductor current.

Piezoelectric materials are essential to many technological applications because of their extraordinary capacity to transform mechanical energy into electrical signals and vice versa. The performance of several piezoelectric materials in transverse mode a mode in which the tangential of the induced stress is parallel to the material's surface is the main subject of this investigation. The piezoelectric materials show different output voltages in different operation modes as they possess different piezoelectric coefficients for different operation modes. In this study, the various piezoelectric materials, viz., AlN, ZnO, PZT-5A, PZT-5H, PZT-5J, and PVDF, are considered and find out which piezoelectric material produces a higher output voltage. These materials play a vital role in the development of sensors, actuators, and devices for harvesting energy. Many piezoelectric sensors, particularly those based on diaphragm, bridge, and cantilever structures, operate primarily in transverse mode. Therefore, it is essential to conduct thorough investigations or analyses to enhance the understanding of their performance and behaviour in transverse mode. In order to vary the performance of the sensors with different piezoelectric materials, a cantilever-shaped sensor is proposed in this study. A 3D model of the proposed sensor is modelled and simulated in COMSOL Multiphysics to verify the output voltages of the sensor. The results are studied by comparing the simulated output voltage for various piezoelectric materials for the applied voltage range from 0-10 kPa. It has been observed that the sensor's output is higher when the piezoelectric material has a higher voltage coefficient (g31).

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

One way to manage the complexity of the design and the implementation of large and adaptive real-time systems is to partition the design into modes of operation. This approach allows designers to break down the complexity of these systems into a number of layers of control (modes), which are then multiplexed in time (by means of mode changes) during system operation. However, due to a lack of a uniform view of modes within the literature, the task of successfully designing complex real-time systems with modes of operation becomes more difficult, if not compromised [1]. In this paper we consider the following recurring issues of modes in real-time systems, both from the application and design concerns: 1) What is a mode of operation, i.e. which features are exclusive to a particular mode of operation that allow its identification and distinction from other modes? 2) What can be understood by the concept of mode changes in realtime systems? The examination of these issues is lacking in the literature and will facilitate the analysis, design and construction of the next generation of complex real-time systems.

In this paper, a fuzzy logic based volume flow control method is proposed to precisely control the force of a pneumatic actuator in an electro-pneumatic system including four on-off valves. The volume flow feature, which is the relationship between the duty cycle of the pulse width modulation (PWM) period, pressure difference, and volume flow of an on-off valve, is based on the experimental data measured by a high-precision volume flow meter. Through experimental data analysis, the maximum and minimum duty cycles are acquired. A new volume flow control method is introduced for the pneumatic system. In this method, the raw measured data are innovatively processed by a segmented, polynomial fitting method, and a newly designed procedure for calculating the duty cycle is adopted. This procedure makes it possible to combine the original data with fuzzy logic control (FLC). Additionally, the method allows us to accurately control the minimum and maximum opening pulse width of the valve. Several experiments are performed based on the experimental data, instead of the traditional theoretical models. Only 0.141 N (1.41%) overshoot and 0.03 N (0.03%) steady-state error are observed in the step response experiment, and 0.123 N average error is found while tracking the sine wave reference.