Distributed commutations pulse-width modulation technique for high-power AC/DC multi-level converters

Abstract

This paper presents a novel dedicated PWM technique for use with single-phase multi-level Cascaded H-Bridge Converters. The proposed modulation strategy aims to minimize the converter commutations and distribute them, for any amplitude of the voltage reference, amongst the different converter cells in order to evenly distribute the heating and stress on the power switches, improving their reliability without compromising the quality of the voltage waveform. Such characteristics are particularly important in high power grid-connected converters used as an interface for renewable energy sources or Smart Grid applications. The technique is described in detail along with the verification of the modulation effectiveness provided by a simulation comparison with other common modulation strategies. Finally, the proposed strategy is experimentally validated by means of different tests using a seven level Cascaded H-Bridge Converter

Review of Power Semiconductor Device Reliability for Power Converters

“…Compared with CPWM, the switching loss of the device is low if the DPWM is adopted, so that the junction temperature fluctuation is low. The 60° discontinuous pulse width-modulation strategies allow better thermal performance and increase the estimated lifetime of the converter compared with SPWM modulation, when FT60 modulation is adopted, the average junction temperature of the device is lower, thereby improving the converter energy conversion efficiency [103], [104]. Although DPWM can improve the lifetime of power devices, it will reduce the (a) (b) power quality of converter.In order to maximization reduction the impact of DPWM on the power quality, in the wind turbine system, a hybrid modulation method based on the wind speed distribution probability is proposed.…”

Multiobjective Modulated Model Predictive Control for a Multilevel Solid-State Transformer

“…In this paper a modulation scheme particularly suitable for high power converter control is implemented in M 2 PC. At every sampling period, only one leg of a single HB is allowed to switch, obtaining a total switching frequency of the CHB that is half of the sampling frequency [22], [23]. This modulation approach equally distributes the commutations amongst the HB modules and, in the case of a 7-Level CHB converter, allows to obtain a device switching frequency equal to one sixth of the sampling frequency.…”

Review of active thermal and lifetime control techniques for power electronic modules

“…In [40] a novel modulation technique is employed to distribute the commutations across multiple H-bridge cells composing a CHB converter. The algorithm counts the commutations of each cell, and tries to synthesize the desired output voltage in a switching cycle giving priority to the H-bridge which totaled fewer commutations.…”