On Current THD Extreme Switching Sequences for a Single-Phase Cascade H-Bridge Inverter with Phase-Shifted PWM and Non-Equal DC Sources

Polichshuk, Ruslan; Zhuldassov, Nurzhan; Ruderman, Alex; Reznikov, Boris

doi:10.1109/epepemc.2018.8521991

Cited by 1 publication

(5 citation statements)

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“…While this effect has a minor impact for singlephase CHB inverters with PS PWM, it causes a significant deterioration of voltage and current THD for three-phase CHB inverters with PS PWM (non-nearest level switching) because source phase voltage synchronization becomes different from the optimal one provided by LS PWM. 3 For a three-phase CHB inverter with PS PWM and more than three unequal DC sources per phase, simulations demonstrated that the best (worst) current THD is obtained by phase switching performed according to the best (worst) DC sources switching sequences for a singlephase CHB inverter, as recently suggested in [11,12]. There is another degree of freedom to be potentially exploited, that is, different carrier sequences in three converter phases by circular permutation of optimal ones.…”

Section: Resultsmentioning

confidence: 65%

“…For a three-phase CHB inverter with more than three DC sources per phase, the single-phase current THD optimal DC source switching sequences reported in [11,12] also work well. Swapping the carriers among the different phases (changing the carriers order) could be considered as an additional degree of freedom that may be used to improve the current THD .…”

Section: Introductionmentioning

confidence: 80%

“…Compared with LS PWM for the same modulation index m = 0.9 (Figure 6), the switching frequency spectrum is spread, and the THD value is slightly larger. In the recent papers [11] and [12], asymptotic formulas of [8] are generalized for a single-phase CHB inverter with PS PWM and non-equal DC sources. Moreover, it is shown that for more than three H-bridges, there are extreme DC source (H-bridge) switching sequences (carrier orders in Figure 1b that minimize (maximize) current THD.…”

Section: Current Thd For a Single-phase Chb Inverter With Ps Pwm And mentioning

confidence: 99%

“…It can be noticed that in the case of four and more CHB cells, the THD with PS PWM is strictly dependent on the DC sources switching sequences. As shown in [11,12], for four H-bridges, the best and worst sequences from the current THD perspective become 1423 and 1243. The switching sequences for the different numbers of H-bridge cells are given in Table 2 with respect to the best and the worst cases.…”

Section: Current Thd For a Single-phase Chb Inverter With Ps Pwm And mentioning

confidence: 99%

“…In addition, minimal current THD requires matching LS PWM bands to DC source voltages that may be difficult to implement in real-life applications. For a single-phase CHB inverter with PS PWM and non-equal DC sources, the optimal current THD for more than three sources is achieved by a proper selection of carrier order (DC sources switching sequence), as recently shown in [11,12].…”

Section: Introductionmentioning

confidence: 99%

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On PWM Strategies and Current THD for Single- and Three-Phase Cascade H-Bridge Inverters with Non-Equal DC Sources

et al. 2019

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Cascade H-bridge (CHB) inverter is an attractive choice for integration of DC sources of different nature, e.g., for distributed generation with energy storage, photovoltaic generation, etc. In general, non-equal DC voltage sources can affect the total harmonic distortion (THD) of the CHB by introducing undesirable low-frequency subharmonics. This paper investigates different level-shifted (LS) and phase-shifted (PS) pulse width modulation (PWM) strategies for single-and three-phase cascade H-bridge inverters with non-equal DC sources from the load current THD minimization perspective. The best current quality is provided by LS PWM, as reported in the literature. The paper provides a simple time domain explanation of LS PWM superiority. However, PS PWM may be a preferable choice for practical applications due to fair power and loss sharing across individual H-bridges. The paper explains how to obtain the best current quality by PS PWM carriers' order arrangement (DC sources switching sequence selection).The paper is organized as follows. Section 2 presents the current THD calculation methodology for non-uniform voltage levels applicable to a single-phase cascade inverter in the case of LS PWM and non-equal DC sources. The analysis of the current THD with PS PWM and non-equal DC sources for the cascade H-bridge inverter is presented in Section 3. The analysis of current THD has been extended to a three-phase cascade H-bridge inverter with non-equal DC sources and presented in Section 4. Section 5 presents the conclusion. Current THD for a Single-Phase CHB Inverter with LS PWM and Non-Equal DC SourcesCurrent THD for a single-phase CHB inverter with LS PWM and equal DC sources can be calculated as suggested in [8] for uniformly distributed voltage levels. In this section, the results of [8] are generalized to acquire non-equal DC sources. For the best harmonic performance (minimal current THD), LS modulation bands must be adjusted to match non-equal DC source voltages (Figure 2).

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Section: Resultsmentioning

confidence: 65%

Section: Introductionmentioning

confidence: 80%

Section: Current Thd For a Single-phase Chb Inverter With Ps Pwm And mentioning

confidence: 99%

Section: Current Thd For a Single-phase Chb Inverter With Ps Pwm And mentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

On PWM Strategies and Current THD for Single- and Three-Phase Cascade H-Bridge Inverters with Non-Equal DC Sources

et al. 2019

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show abstract

On Current THD Extreme Switching Sequences for a Single-Phase Cascade H-Bridge Inverter with Phase-Shifted PWM and Non-Equal DC Sources

Cited by 1 publication

References 13 publications

On PWM Strategies and Current THD for Single- and Three-Phase Cascade H-Bridge Inverters with Non-Equal DC Sources

On PWM Strategies and Current THD for Single- and Three-Phase Cascade H-Bridge Inverters with Non-Equal DC Sources

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