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This article proposes a controller for dc–dc converters to achieve fast load-transient responses. The controller is developed for both continuous conduction mode (CCM) and discontinuous conduction mode (DCM) of operation. The main idea is developed for buck converters, but it is shown that the proposed controller can be applied to other topologies, such as the noninverting buck–boost converter. The controller derivation, analysis, and experimental verifications are provided in both CCM and DCM, and its performance is compared with other methods. The main advantage of the proposed controller is that it minimizes the recovery times associated with load-transient responses in dc–dc converters while maintaining component sizes and other system parameters within the acceptable range. The proposed controller can be used to minimize load transients in electronic portable devices and electric vehicle charging. [ABSTRACT FROM AUTHOR]

Steady-state models of power converters that provide accurate closed-form expressions for converter waveforms are extremely valuable for converter analysis and design, and enable comparative evaluation of different converter topologies. An obstacle in the development of such models is the inherent nonlinearity of switching power converters. This article presents a systematic procedure to model a broad class of power converters using ordinary differential equations (ODEs) with periodic and discontinuous inputs, and provides an approach to determine closed-form expressions for their steady-state waveforms. The formal mathematical proof of the proposed approach to finding closed-form expressions for the steady-state solution of ODEs with periodic and discontinuous inputs, Laplace-based theorem (LBT), is also presented. The presented modeling procedure and LBT, collectively called Laplace-based steady-state modeling (LBSM), serves as an effective analysis and design tool for power converters. The value of LBSM is demonstrated by using it to obtain closed-form expressions for the steady-state waveforms of different types of converters. In particular, two commonly used topologies—the series resonant converter and the phase-shift converter—are analyzed and compared using LBSM and their optimum operating conditions and applications are discussed. The converter waveforms, soft switching ranges and other characteristics obtained using LBSM are also validated through simulations and experiments. [ABSTRACT FROM AUTHOR]

A new distributed control scheme and charge flow analysis is presented for voltage balancing of series connected battery cells using nondissipative modular power electronics. Each modular bridge is connected across two battery cells using a high frequency transformer and an asymmetrical half-bridge. This results in using one switch and one diode per battery cell. Intrabridge charge transfer equalizes the voltage of two battery cells within a module using coupled transformer windings. Each modular bridge is connected to adjacent bridges by connecting transformer windings within each module. This allows interbridge charge transfer and the balancing of pairs of battery cells, both within adjacent bridge modules and modules more removed. The proposed controller uses a distributed control strategy whereby the control of each modular bridge monitors its own battery cell voltages and also those of adjacent bridges, thus reducing the number of feedback sensors. Detailed analysis is presented that quantifies the flow of charge between a number of series connected battery cells ($ N$ battery cells). A per-unit design methodology is used to illustrate the system charge flow characteristics. Simulations, design guidelines and experimental results are presented to validate the proposed method. [ABSTRACT FROM AUTHOR]

A fast and robust fixed switching frequency peak current controller for DC–AC converters is presented. The proposed method tends to mimic the switching behavior of pulse width modulation (PWM) techniques, so it features all the advantages of peak current controllers (such as simplicity, fast transient, and optimum dynamic response), with the superiority of fixed switching frequency and harmonic free output. The proposed method is a generalized approach that can be applied to different PWM schemes. The method is specifically elaborated for single-phase distributed generation applications, using various inverter topologies and mimicking different PWM schemes. Moreover, adaptive bands are proposed to provide active damping for the controller, to extend use of the proposed method for inverters with LCL output filters. Feasibility and performance of the controller is shown by means of simulations and experiments. [ABSTRACT FROM AUTHOR]

A new bidirectional multilevel converter topology called the sparse modular multilevel converter suitable for high power ac/ac applications is presented. The proposed topology has fewer insulated-gate bipolar transistor switches and capacitors compared with conventional approaches. Moreover, a salient feature of the proposed topology is that more than half of the switches are operating in soft switching conditions, which considerably decreases the switching losses of the converter. The theoretical calculations and simulation results are provided to verify the feasibility of the proposed topology. [ABSTRACT FROM PUBLISHER]