This paper proposes a new single-phase single-stage switched-boost inverter with four switches. Like the quasi-Z-source inverter (qZSI) and quasi-switched boost inverter (qSBI), the proposed inverter has the main features as continuous input current, buck/boost voltage with single-stage conversion and shoot-through immunity. Compared to the qSBI, the proposed inverter uses one more capacitor and one less switch. This paper presents the operating principles, PWM control strategy, parameter design guidelines, and simulation results for the proposed inverter. To verify the performance of the proposed inverter, an 800 W prototype was built with an 110 V/50 Hz output voltage in stand-alone and grid-connected modes. The simulation and experimental results matched those of the theoretical analysis.

In this paper, a modified three-phase two-level voltage source inverter is proposed. By combining the conventional three-phase H-bridge inverter with a switched-capacitor-voltage-doubler network, the DC-link voltage of the proposed inverter is double with respect to the input DC voltage. As a result, the output voltage of the proposed inverter can be higher than the input DC voltage. Furthermore, a common-mode voltage (CMV) of the proposed inverter can be reduced through controlling the two additional switches based on the space vector pulse-width modulation. Compared to the existing modulations and topologies, the variation in CMV can only be up to 16.6% of DC-link voltage. Furthermore, the voltage stress across additional switches and diodes is equal to half of DC-link voltage. Mathematical analysis, operating principles, and comparison of the proposed three-phase two-level voltage source inverter with the conventional three-phase voltage source inverters are presented. The simulation results based on PLECS software verify a good performance of the proposed inverter. Finally, a laboratory prototype based on a TMS320F280049 DSP is developed and experimental tests are carried out to validate the effectiveness of the proposed three-phase inverter topology

This paper proposed a novel family of PWM strategies for single-phase quasi-switched boost inverter (qSBI). By combining shoot-through mode in the inverter's switches and the turning-on state of an additional switch, the qSBI produced a high voltage gain without adding any passive components. Compared to the conventional PWM strategy for the same input and output voltage gain, the introduced PWM strategies for qSBI could reduce voltage stress across semiconductors and capacitor with the following additional merits: having smaller high-frequency inductor current and capacitor voltage ripples, using high modulation index with low shoot-through duty cycle, and having higher efficiency. Circuit analysis, operating theories, and simulation results of the single-phase qSBI with the introduced PWM5 strategy are shown. A 500-W laboratory prototype was constructed and the effectiveness of the introduced PWM strategy was validated. The qSBI with the proposed PWM strategies is suitable for applications where the required voltage gain lies between 2 and 3.

In grid-connected photovoltaic (PV) systems, a transformer is needed to achieve the galvanic isolation and voltage ratio transformations. Nevertheless, these traditional configurations of transformers increase the weight, size, and cost of the inverter while decreasing the efficiency and power density. The transformerless topologies have become a good solution. However, the problem is that commode-mode voltage and leakage current can occur via the stray capacitors between the PV array and the ground of the inverter. Various transformerless inverters have been introduced with different techniques, such as reducing the common-mode voltage or eliminating the leakage current. Furthermore, to introduce the development of transformerless PV inverters, especially in three-phase two-level inverter systems, this paper provides a comprehensive review of various common-mode voltage reduction three-phase two-level inverters.

This article introduces a new switched-capacitor-based multilevel inverter topology. The proposed structure consists of six switches with a single dc voltage source and three floating capacitors, and it is capable of producing a six-level output voltage waveform with voltage boosting gain of 2.5. Moreover, the voltages of the capacitors are constructively balanced because they are directly charged to fixed voltage by the input dc voltage source. The operating principles, circuit description, and pulsewidth modulation control technique for the proposed topology are presented, along with the selection of components. A comparative study between the proposed inverter and other existing multilevel inverter topologies is also discussed. The simulation results are provided to confirm the theoretical analysis. Furthermore, the experimental results obtained from a laboratory-built prototype under different conditions are presented as a comparison to assess the performance of the proposed inverter.

In a single-stage buck-boost quasi-switched boost inverter (qSBI), the shoot-through state insertion causes high amplitude common-mode voltage. Consequently, the qSBI becomes less attractive in transformerless photovoltaic (PV) systems. In this paper, a novel space vector pulse-width modulation for a modified qSBI is introduced to reduce the magnitude of common-mode voltage and push the modulation index up to 1. By properly choosing the shoot-through interval time, shoot-through states are considered to be inserted for boosting voltage and also reducing the THD value of the output voltage. The mathematical analysis and operating principles of the converter are discussed and verified through PSIM simulations. Finally, an experimental prototype is validated based on a TMS320F28335 DSP microcontroller and a DE0-Nano FPGA digital control platform.