Time filter

Source Type

Petah Tikva, Israel

Ruderman A.,Elmo Motion Control Ltd | Reznikov B.,General Satellite Corporation
IEEE International Symposium on Industrial Electronics | Year: 2010

Voltage total harmonic distortion and related quadratic criteria are accepted as figures of merit of a multilevel PWM converter voltage quality. The dominating frequency domain voltage quality evaluation approach, in fact, is essentially numerical as it involves infinite double Fourier series expansion with Bessel function coefficients and requires high switching harmonics count. Suggested time domain approach for multilevel PWM converter voltage quality evaluation delivers simple piece-wise analytical solutions that clearly reveal the dependence on modulation index for an arbitrary number of voltage levels. The results are applicable to any type of multilevel converters with optimal nearest three space vector PWM allowing for fast comparative evaluation of voltage quality for filterless grid-connected converters with different levels count. © 2010 IEEE. Source

Thielemans S.,Ghent University | Ruderman A.,Elmo Motion Control Ltd | Reznikov B.,General Satellite Corporation | Melkebeek J.,Ghent University
IEEE Transactions on Power Electronics | Year: 2012

Flying-capacitor converters (FCCs), like most multilevel converter topologies, require a balancing mechanism of the capacitor voltages. FCCs feature natural voltage balancing when a special modulation technique is used. The classic methods, such as phase-shifted pulse width modulation (PS-PWM), result in very slow balancing for some duty-ratio ranges. Previous work has shown that for a single-leg five-level FCC, one time constant is infinite for a zero desired output voltage. In this paper, a modified PS-PWM scheme for a single-leg five-level FCC is presented, which results in faster balancing over the total duty-ratio range. The modified PS-PWM scheme is studied, resulting in an averaged voltage-balancing model. This model is verified using simulations and experiments. The modified PS-PWM scheme solves the slow-balancing problems of the normal PS-PWM method for odd-level FCCs, while maintaining the passive control property, and it provides a self-precharge capability. © 2012 IEEE. Source

Ruderman A.,Elmo Motion Control Ltd | Reznikov B.,General Satellite Corporation
IEEE International Symposium on Industrial Electronics | Year: 2010

Accepted voltage balancing dynamics research methods flying capacitor converters are based on frequency domain transformations that involve double Fourier series with Bessel function coefficients. Therefore, these methods require high mathematical skills, are not truly analytical and difficult to use in engineering practice. In this paper, a "physical" approach to switched systems analysis based on stitching analytical solutions for consecutive switching subintervals, is applied to flying capacitor average voltage balancing dynamics analysis. It is shown that time domain averaging methodology generates simple analytical solutions that reveal the dependences on load parameters, carrier frequency, and normalized DC voltage command (AC modulation index). The power of suggested approach is demonstrated using single-leg converter voltage balancing dynamics analysis examples. © 2010 IEEE. Source

Busquets-Monge S.,University of Barcelona | Ruderman A.,Elmo Motion Control Ltd
IEEE International Symposium on Industrial Electronics | Year: 2010

This paper presents four carrier-based PWM strategies for diode-clamped converters of any number of levels and any number of legs (phases). These carrier-based PWM strategies guarantee the dc-link capacitor voltage balance in every switching cycle without the need of additional hardware and with low dc-link capacitance values for any modulation index and load, provided that the sum of leg currents equals zero. The performance of the presented carrier-based PWM strategies, in terms of dc-link capacitor voltage balance and total harmonic distortion in the output line-to-line voltages, is evaluated through simulation, showing a tradeoff between the simplicity of the carrier-based PWM implementation and its total harmonic distortion performance. © 2010 IEEE. Source

Ruderman A.,Elmo Motion Control Ltd | Reznikov B.,General Satellite Corporation
Proceedings of EPE-PEMC 2010 - 14th International Power Electronics and Motion Control Conference | Year: 2010

Voltage source converter Pulse Width Modulation common-mode voltages have an adverse affect of inducing motor shaft voltages and bearing currents that result in premature bearings failure. Common-mode voltage cancellation PWM strategies significantly compromise the optimal voltage quality of the nearest three space vector modulation. The paper presents a quantitative estimation of associated motor PWM loss increase for a three-phase multilevel converter. © 2010 IEEE. Source

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