Soft‐switching modulation of the multilevel cascaded H‐bridge inverter under DC source fault

Abstract

Cascaded H‐bridge inverter (CHBI) is widely used in the industry application for its outstanding features. However, CHBI needs a large number of isolated DC sources. If some of the DC sources are out of work, the DC voltage cannot maintain the desired value and even decreases to zero, thus degrading the quality of the output voltage of the CHBI. Thus, a soft‐switching modulation strategy based on the carrier phase shift SPWM is proposed in this paper to cope with the DC source failure. The strategy is proposed to achieve two goals: 1) one is to adjust the DC voltage of faulty cells back to the normal; 2) the other one is to make the pulse width modulation (PWM) pulses of each cell change without cell voltage level‐skip. The correction and efficiency are verified by a prototype of three‐cell CHBI built in the laboratory.

A Comprehensive Review of Compensation Control Techniques Suitable for Cascaded H-Bridge Multilevel Inverter Operation with Unequal DC Sources or Faulty Cells

“…Figure 2 illustrates the operation of the inverter under ideal conditions, assuming that all power cells have equal DC voltage sources in their input DC links. There has been a significant amount of research conducted by scholars and engineers on cascaded H-bridge multilevel inverters in recent decades [15][16][17][18][19], which can be summarized into four main aspects:…”

“…Energies 2024, 17, 722 3 of 18 bridge multilevel inverters in recent decades [15][16][17][18][19], which can be summarized into four main aspects:…”