This paper proposes an H7 current source inverter (CSI) consisting of a single shunt-connected silicon carbide (SiC) switch and a traditional silicon (Si) H6 CSI circuitry, which could employ the superior characteristics of SiC switch to significantly increase the whole switching frequency with expected low losses simultaneously. In order to reduce the switching counts and also realize the zero current switching (ZCS) ability for rear-end CSI circuitry, two kinds of H7 CSI modulation schemes have been proposed with either superior output performance or minimal switching counts. Consequently, the proposed H7 current source inverter can perform as an all-SiC-switch circuitry, and guarantee high performance and high efficiency with a reduced DC inductance. It could be a cost-effective solution to address the efficiency issue of current source inverters. MATLAB simulations and experimental verifications have been presented in order to show the performance of the proposed inverter.

Two-dimensional transition metal dichalcogenides (2D TMDs), such as WS₂, are considered to have the potential for high-performance gas sensors. It is a pity that the interaction between gases and pristine 2D WS₂ as the sensitive element is too weak so that the sensor response is difficult to detect. Herein, the sensing capabilities of Al- and P-doped WS₂ to NO, NO₂, and SO₂ were evaluated. Especially, we considered selectivity to target gases and dopant concentration. Molecular models of the adsorption systems were constructed, and density functional theory (DFT) was used to explore the adsorption behaviors of these gases from the perspective of binding energy, band structure, and density of states (DOS). The results suggested that doping atoms could increase the adsorption strength between gas molecules and substrate. Besides, the sensitivity of P-doped WS₂ to NO and NO₂ was hardly affected by CO₂ or H₂O. The sensitivity of Al-doped WS₂ to NO₂ and SO₂ was also hard to be affected by CO₂ or H₂O. For NO detection, the WS₂ with 7.4% dopant concentration had better sensitive properties than that with a 3.7% dopant concentration. While for SO₂, the result was just the opposite. This work provided a comprehensive reference for choosing appropriate dopants (concentration) into 2D materials for sensing noxious gases.

This paper proposes an eight-switch, three-phase, five-level current source inverter (CSI), which employs only one traditional H6 inverter and two shunt branches at the dc side to realize the five-level switching. The corresponding space-vector-modulation (SVM) strategy for the proposed CSI topology is also presented, which uses the two shunt-connected power switches to add certain special modulation-state segments to ensure the switching instants completed under lower current stresses and lower power dissipation. Compared with the state-of-the-art CSI solutions, the proposed topology has a comparable hardware cost as the three-level H6 CSI, while outputs five-level currents. The low-output total harmonic distortion (THD) may help to reduce the sizes of the passive components in the system, and the modulation scheme reduces the switching and conduction losses of the semiconductor switching devices in the H6 CSI module, which can make it possible to increase the output current rating of the system in a certain degree. Simulation and experimental results verified the performance of the proposed CSI.

Nowadays, one of the major challenges to develop the HVDC grid is the effective and economical dc fault protection technique, which is normally realized by the dc circuit breakers (DCCBs). However, the dc circuit breaker is quite complex and expensive. Therefore, to explore an alternative solution, this paper proposes a bipolar cascaded modular H7 current source converter for HVDC grid with simple dc fault ride through capability and then analyzes its dc fault behavior and consequently proposes the protection scheme, which can reduce the design requirement of DCCBs, even handle dc faults only with mechanical switches. PSCAD simulation and experiment results are demonstrated to validate the feasibility of the proposed topology and fault protection scheme.

In order to achieve low carbon emissions in the power grid, the impact of new energy grid connections on the power grid should be reduced, as well as the peak-to-valley load difference caused by large-scale electric vehicle grid connections. This paper proposes a two-tier, low-carbon optimal dispatch master–slave game model involving virtual power plant operators as well as electric vehicle operators. Firstly, the carbon flow is tracked based on the proportional sharing principle, and the carbon emission factor during the charging and discharging process of electric vehicles is calculated. Secondly, the node carbon potential and time-sharing tariff are used to guide and change the charging behaviour of electric vehicles and to construct a master–slave game model for low-carbon optimal scheduling with the participation of multiple subjects, with economic scheduling at the upper level of the model and demand response scheduling at the lower level. Finally, the IEEE30 node system is used as an example to verify that the method adopted in this paper can effectively reduce the peak-to-valley difference of loads, reduce the carbon emissions of the grid, and reduce the cost of each participating entity.

The current source inverter (CSI) is essentially a converter with inherent boost capability and has been preliminarily applied in the field of renewable energy generation systems. However, conventional CSIs are mostly operated independently. Several existing multilevel CSI topologies entirely rely on parallel combinations, which seems to be not very suitable for capacity expansion. To solve this issue, this paper proposes a concept of three-phase boost-stage coupled current source inverter (BSC-CSI) through the duality principle, which can output multi-level currents with a reduced number of switches as well as hardware costs. Compared with the state-of-the-art CSIs, the proposed BSC-CSI can notably simplify the implementation of the multi-level modulation scheme and meanwhile ensure the power devices switch under lower current stress. To further take full advantage of the modularity and scalability, the BSC-CSI can be constructed by hybrid using silicon-carbide (SiC) and silicon (Si) based semiconductor switches for improving efficiency. The experimental results have verified the theoretical findings.