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This study addresses the calculation of current total harmonic distortion (THD) for three-phase (3P) pulse-width modulation (PWM) inverters. First, it demonstrates how an analytical approach to PWM current ripple normalised mean square (NMS) calculation introduced in the late 1980s for a two-level (2L) inverter can be used for current THD evaluation. Second, it is shown how to evaluate current THD for a three-level (3L) 3P inverter using the current ripple NMS concept. Though considered is a 3P cascaded inverter with one H-bridge per phase, the results are applicable to popular 3L neutral point clamped (T-type) and flying capacitor inverters. [ABSTRACT FROM AUTHOR]

Here, accurate transresistance calculations for the coupled case and mathematical modelling are provided for dual input–output switched capacitor converter (SCC). This converter offers two different output voltages and produces 36 voltage conversion ratios. The dual input–output SCC is portable and operates by considering either sources or the combination of both Vs1 and Vs2 as input sources. The proposed dual input–output SCC has the ability to vary 54 voltage ratios. An efficient low‐power SCC is designed for an input voltage range of 1.5–5 V and it gives dual‐output voltages of 1–10 V. The proposed converter can operate in both buck and boost modes. The SCC has high drive capability of load current in the range of 10 µA to 100 mA that is adjusted by varying the operating frequency. The accurate equivalent resistance for both coupled and decoupled load cases is found and validated. The results are verified through PSIM simulations and validated experimentally. The mathematical, simulation, and experimental results give excellent proof for proposing the newly designed converter for applications requiring large conversion ratios eliminating inductors. [ABSTRACT FROM AUTHOR]

Reported capacitor average natural voltage balancing dynamics analysis methods are mostly based on frequency-domain Fourier transformations that involve infinite series. Therefore, these methods require high mathematical skills, are not truly analytical and difficult to use in engineering practise. This study suggests a time-domain power averaging-based approach to the analysis of a multilevel DC–DC flying capacitor converter (or, more generally, switched capacitive converter) aperiodic (non-oscillating) average voltage balancing dynamics. Simple analytical solutions are illustrated by single and dual capacitor converter examples that include pure resistive load and balance booster circuit. Theoretical results are supported by simulations and experimental verification. [ABSTRACT FROM AUTHOR]

ABSTRACT Flying capacitor converters (FCCs) are recently attracting considerable interest because of their inherent natural voltage balancing property. We develop a sampled-data model for a single-phase single-leg three-level FCC. This provides a closed-form expression for the system dynamic behavior after each switching cycle. Analysis of this model provides considerable insight on the FCC and its natural balancing property. In particular, we prove that the natural balancing property indeed holds whenever the switching frequency is sufficiently high. We also rigorously analyze dynamic properties such as the capacitor time constant and relate them to the parameter values of the load, carrier frequency and duty ratio. These results shed light on the intricate relationship between the FCC parameters and its short- and long-term dynamic behavior. Copyright © 2011 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]