Hybrid 17‐level inverters based on T‐type flying‐capacitor and switched‐capacitor

Abstract

The purpose of this work is to use fewer components to generate more output levels for power interfaces of low dc voltage sources such as fuel cells. First, two switched‐capacitor voltage lifters (SCVLs) with similar structure and same function are summarized. Each of them uses a single capacitor and has the advantage of identical voltage stress for all components. Then, the SCVLs are combined with a T‐type unit to develop two 17‐level inverters. The SCVLs is responsible for voltage boosting, while the T‐type unit uses two flying capacitors to increase the number of output levels. In addition to the use of three capacitors, the two 17‐level inverters employ 13 and 14 semiconductor switches respectively, and all components' voltage stresses do not exceed the dc input voltage. Simple structure, reduced capacitors' count, and low components' voltage stress are the main merits of the proposed inverters compared with other 17‐level inverters. Beyond theoretical analysis, both steady‐state and dynamic performances are verified experimentally, and the highest efficiency measured by the experiment is up to 97.8%.

Symmetric and Asymmetric Multilevel Inverter Topologies With Reduced Device Count

“…Various configurations of SCMLIs have been reported in the literature in recent years. Various 13 and 17-level SC-MLI with single-phase ac output voltage are reported in [7], [8], [9], [10], [11], [12], [13], [14], [15], [16], [17], [18], [19], [20], [21], [22], [23], [24], [25], and [26]. In [21], [22], [23], and [24], two-stage 13-level SC-MLI configurations are discussed, which involve the boosting operation dc voltage in one stage and the production of ac output voltage in another stage.…”

“…The 13 and 17-level SC-MLI requiring multiple sources are reported in [7], [8], [14], [15], [16], [19], [20], [21], and [27]. The 13 and 17-level SC-MLIs requiring only single source are discussed in [5], [10], [11], [12], [13], [17], [18], [22], [23], and [28]. In [5], two SC-MLI configurations are suggested, which are used to provide 13-level output ac voltage requiring switches having reduced values of voltage stresses and PIV or switch stress.…”

“…The suggested topology requires capacitors of reduced size. The 17-level SC-MLI, including single input dc source, is suggested in [17] and [18]. The SC-MLI configuration suggested in [17] offers a high value of TSV of the switch string.…”

“…The 17-level SC-MLI, including single input dc source, is suggested in [17] and [18]. The SC-MLI configuration suggested in [17] offers a high value of TSV of the switch string. To ensure 17-level output ac voltage using switches having low value of TSV, an improved 17-level SC-MLI topology is suggested in [18].…”

“…The SC-MLI configurations suggested in [5], [10], [11], [12], [13], [17], [18], [22], [23], and [28] require single dc input voltage source for generation of 13 and 17-level ac output voltage. A single source is used to charge the capacitors, and a series connection of this source and capacitors may be used to charge other capacitors.…”