Modular double‐cascade converter for high‐power medium‐voltage drives

Abstract

The modular double-cascade converter (MDC) is a new multilevel AC/AC converter topology, which has a modular structure. The proposed topology can be used in medium-voltage motor and generator drives, and in interfacing of grids of different voltages and frequencies. MDC is formed with two sets of cascaded H-bridges where the isolation of the power modules is carried out with medium-frequency multiwinding transformers. Although the transformers have a transformation ratio of one, the presented topology can be used to transform the voltage level by using different connections for the input and output H-bridges. The number of steps of input and output voltages can be varied by connecting the modular units of MDC in series or in parallel. The functionality of the topology is verified by simulations of a seven-level version for a 3.3 kV, 1.1 MW application and experimental results are shown for a 400 V, 76 kW three-level inverter. In particular, an inherent submodule energy sharing capability through the transformer is analysed and assessed by simulations and experimental tests.

Review of dc–dc converters for multi‐terminal HVDC transmission networks

“…For many decades researchers have recognised the possibilities multi-terminal high-voltage dc (HVDC) transmission networks can offer when compared with well-established high-voltage ac systems [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15]. For the majority of this period, the difficulty of power reversal in complex multi-terminal networks based on line commutating converter high-voltage dc (LCC-HVDC) technology has prevented development of generic dc grids with seamless control over the power flow in any of its branches [16].…”

A novel fault‐detection methodology of proposed reduced switch MLI fed induction motor drive using discrete wavelet transforms

“…Multilevel inverter (MLI) itself influences the several advantages over the standard square‐wave inverter, such as RMS quality voltage and current wave‐shapes, low dv / dt stress, low electromagnetic interference compatibility, greater working efficiency, low harmonic profile, and so on. Additionally, a MLI furnishes high‐power status and enables to control the speed of the induction motor drive 3,4 . The traditional MLI topologies are neutral‐clamped type, 5 flying‐capacitor type, 6 and cascaded H‐bridge (CHB) type, 7,8 and play a significant role in many applications.…”

Wavelet Transform Based Fault Identification and Reconfiguration for a Reduced Switch Multilevel Inverter Fed Induction Motor Drive

“…Multilevel inverters have gained importance in the past few decades since they are suitable for high voltage and high-power applications by virtue of their ability to synthesize waveforms with improved harmonic spectrums and lower total harmonic distortions (THD). Compared to the classical square-wave or quasi-square wave inverters, the multilevel inverter has a number of advantages such as near-sinusoidal wave-shapes, low common-mode voltage, low dv/dt voltage stress, low harmonic profile, low electromagnetic interference effects, good operating efficiency, and regulation of the drive speed [3,4]. Various formal multilevel inverter structures are the diode-clamped multilevel inverter [5], the flying-capacitor multilevel inverter [6], and cascaded H-bridge multilevel inverter (CHB-MLI) [7].…”