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In this paper, a fifth-order boost point-of-load converter is developed by cascading a modified fourth-order boost converter with a combination of L–C and diode. This topology has the following salient features: Single-switch topology, common ground between source and load, low-voltage stress across intermediate capacitors, and voltage gain same as other reported fifth-order boost converters with no common ground. Steady-state and dynamic analyses demonstrate the proposed converter's boosting feature and dynamic performance, respectively. A contoured robust Bode plot methodology is employed to design the robust voltage-mode controller to ensure load voltage regulation in the presence of uncertainties. The necessary and sufficient conditions under which the designed controller guarantees the load voltage regulation and robust stability are obtained. A step-by-step robust controller design procedure is outlined. The salient features of the proposed converter and its robust performance are studied analytically, using the MATLAB platform, and validated experimentally on a 60-W prototype module. [ABSTRACT FROM AUTHOR]

Flyback/forward derived power converters offer operational simplicity, but require active clamping circuits to reduce switch voltage stress and improve the converter efficiency. This paper presents an active clamping circuit technique, which additionally ensures enhancement in the converter voltage gain. This is enabled by the proposed auxiliary circuit, which introduces a charged capacitor in series with the primary source during the energizing interval. Two circuits are designed on this principle, and design and operation of both are presented for discontinuous conduction modes. It is shown that the voltage gain of these circuits increases with increase in the leakage inductance, which is an improvement over existing converters. Also, in one circuit primary (secondary) winding, rms current is similar to (lower than) that in a typical ideal flyback converter, leading to improvement in power density. Operation and analyses of this variant are experimentally verified with a 400-V laboratory prototype. [ABSTRACT FROM AUTHOR]

This paper investigates a multilevel inverter composed of series/parallel-connected H-bridges. The presented structure can be used for applications in which the use of semiconductor switches with low-voltage and low-current ratings is intended. A comprehensive system model, an overall control strategy to adjust the output voltage with constant magnitude and frequency, and a level-shifted PWM (LS-PWM) strategy based on a voltage vectors unidimensional analysis and a plane analysis are presented. The LS-PWM is capable of mitigating the low-frequency circulating current, thus generating multilevel voltage signals with low harmonic distortion, maximum number of levels, and low dv/dt. In addition, considering a wide range of values of voltages and currents and various power levels, the total converter losses are reduced compared with the conventional multilevel converters. Two multilevel conventional inverters with the same number of semiconductor switches are used for comparison. Simulation and experimental results demonstrate the feasibility of the studied converter. [ABSTRACT FROM AUTHOR]

This paper presents a power factor correction (PFC)-based bridgeless Luo (BL-Luo) converter-fed brushless dc (BLDC) motor drive. A single voltage sensor is used for the speed control of the BLDC motor and PFC at ac mains. The voltage follower control is used for a BL-Luo converter operating in discontinuous inductor current mode. The speed of the BLDC motor is controlled by an approach of variable dc-link voltage, which allows a low-frequency switching of the voltage source inverter for the electronic commutation of the BLDC motor, thus offering reduced switching losses. The proposed BLDC motor drive is designed to operate over a wide range of speed control with an improved power quality at ac mains. The power quality indices thus obtained are under the recommended limits of IEC 61000-3-2. The performance of the proposed drive is validated with test results obtained on a developed prototype of the drive. [ABSTRACT FROM PUBLISHER]

This paper deals with the design, analysis, simulation, and development of a power-factor-correction (PFC) multiple-output switched-mode power supply (SMPS) using a bridgeless buck–boost converter at the front end. Single-phase ac supply is fed to a pair of back-to-back-connected buck–boost converters to eliminate the diode bridge rectifier, which results in reduction of conduction losses and power quality improvement at the front end. The operation of the bridgeless buck–boost converter in discontinuous conduction mode ensures inherent PFC operation and reduces complexity in control. The performance of the proposed multiple-output SMPS is evaluated under varying input voltages and loads by simulating this circuit in MATLAB/Simulink environment, and the results obtained through simulation are validated experimentally on a developed prototype. Both simulation and experimental results demonstrate the improved performance of the proposed SMPS. [ABSTRACT FROM AUTHOR]

Digital average current controllers for boost power factor correctors (PFCs) are usually designed for continuous conduction mode (CCM). However, discontinuous conduction mode (DCM) appears in the inductor current near the zero crossings of the input current at light loads, resulting in input current distortion. It is caused by inaccurate average current values obtained in DCM and by the linear CCM PFC controller that is unable to ensure input current shaping in DCM whereby the converter exhibits nonlinear characteristic. This paper proposes a simple digital DCM control scheme that is achieved with minimal changes to the CCM average current control structure. It is mathematically and computationally simple. The result of all arithmetic operations in the proposed current control loop to obtain the desired control output can be achieved in a single clock cycle, whereas other DCM control schemes require multiple clock cycles. Good input current shaping is achieved in both CCM and DCM with the proposed CCM–DCM digital controller. [ABSTRACT FROM AUTHOR]