Novel modulator for the hybrid two-cell flying-capacitor based ANPC converter

Abstract

Abstract-Among the multilevel converters present in the industry, the hybrid flying-capacitor based active-neutral-pointclamped converter is very recent. It presents good features such as high quality output voltage, high modularity and easy extension to achieve a high number of levels with reduced number of power devices. This paper introduces a simple modulator for the single-phase two-cell hybrid flying-capacitor based activeneutral-point-clamped converter. The modulation technique is based on the determination of a switching sequence formed by two switching states which generate the two nearest voltage levels to the reference phase voltage. Some extra calculations are added to the modulation method to control the dc-link capacitors and the floating capacitor voltages. The computational cost of the modulation technique is low only including simple comparisons and mathematical expressions. Simulation results show the high quality output voltages and currents including the dc voltage control.

The seven-level flying capacitor based ANPC converter for grid intergration of utility-scale PV systems

“…This process requires active balancing of the two capacitors by selecting the corresponding states that regulate the voltages towards the reference values. A number of methods have been proposed in the literature including natural balancing of voltage level modulation [13], nearest voltage level [14] and a generalized modulator suitable for SPWM and selective harmonic elimination PWM techniques [16].…”

“…These configurations, also known as hybrid multilevel converters, have attracted research interest in the last decade and certain technologies are already commercially available. Hybrid multilevel converters include topologies based on the cascaded connection of H-bridges to the output of typical converters [6], [7] as well as the active NPC family of multilevel converters [8]- [14].…”

Topologically reduced multilevel power converters for alternative energy sources

“…The first 5L-ANPC technology, ACS 2000, has been successfully introduced by ABB Ltd in the industries for voltage drives up to 6.9 kV [104][105][106]. Over the recent years, several different modulation methods are implemented for the 5L-ANPC such as space vector PWM (SVPWM) [104,105,[107][108][109][110], selective harmonic elimination PWM (SHE-PWM) [106,111,112] and carrier-based PWM (CB-PWM) [74,[113][114][115]. Nonetheless, it should be noted that the quality of the synthesized output line-to-line voltage waveforms also depends on the operating conditions of the inverter.…”

“…There are reported control methods such as modifying the switching pulse width of PSC-PWM through a PI regulator [115], using redundant switching states based on SHE-PWM [112] or nearest-level modulator [108,109]. However, the computational efforts of these are increased especially for higher mL-ANPC.…”