Harmonic cancellation for a twelve-pulse rectifier using DC bus modulation

Abstract

This paper presents a new method to eliminate harmonics drawn by a twelve-pulse rectifier through modulation of the dc bus. A PWM converter with low ratings is inserted in the dc link and controlled in a fashion that results in sinusoidal currents at the input. The bulk of the power transfer is handled by the diode bridges, while the additional PWM converter deals only with a ripple voltage.Circuit implementations applicable for series and parallel connections of the two constituent six-pulse sections are described. The proposed approach offers a low-cost alternative to PWM rectifiers or 18-pulse rectifiers. Operation of the circuit is verified through computer simulations.

A Rapidly Reconfigurable DC Battery for Increasing Flexibility and Efficiency of Electric Vehicle Drive Trains

“…The concept of quasi-stationary dc-link voltage adjustment was studied with monolithic dc/dc stages, reflecting the topology of Toyota's hybrid synergy drive and other in-production vehicles [54]. A modulation of the dc voltage can substantially reduce the switching loss in the subsequent drive inverter [7], [25], [54], [55], [80], [81]. However, the monolithic dc/dc stage still switches the full system voltage and current, requiring highvoltage, high-current components, suffers from a trade-off between control instabilities and dynamics, and does only solve some of the issues discussed in Section I.…”

“…The concept of shared modulation was also studied previously. Raju and colleagues as well as Klumpner and Zargar, for instance, insert a full-bridge circuit between the backend dc link and the frontend inverter to shape the dc-link waveform-the use of the full-bridge relegates the high-voltage switching to low-voltage parts [54], [55], [80]. However, when used for EV drive trains with batteries, those topologies only offer a narrow dc-link voltage range, losing the ability for adjusting the overall voltage to the needs of the drive, although that was one of the initial motivations of dc-link modulation.…”

“…In equivalent terms, no zero-voltage vectors are required. The frontend inverter therefore spares 2 /3 of switching compared to conventional space-vector pulse-width modulation (SVPWM), or 1 /2 compared to discontinuous pulse-width modulation (DPWM) and still without the distortion issues of DPWM [25], [54], [55]. The spared switching duty is relegated to the adaptive dc battery backend, but the latter incurs much less switching loss due to the fractionized switching voltage and the use of fieldeffect transistors (FETs) and can generate higher output quality due to a higher number of output levels.…”

“…In contrast to previous approaches with monolithic dc/dc stages and other separate units [7], [25], [54], [55], [80], [81], we use a modular adaptively reconfigurable multilevel dc battery as the backend connected to the frontend inverter through a dc link (Fig. 1).…”

Closed-Loop Sinusoidal Input-Current Shaping of 12-Pulse Autotransformer Rectifier Unit With Impressed Output Voltage

“…This would result in a relatively higher overall system efficiency as the main power conversion would be still performed purely passive by the rectifier bridges. An according concept is described in [7] for a conventional transformer-isolated 12-pulse rectifier systems, but has not been analyzed for hybrid ATRU so far.…”