High-gain bidirectional dc–dc converters are so popular in many applications, such as drives, photovoltaic systems, electric vehicles (EVs), etc. This article proposes an extendable bidirectional common-ground dc–dc converter suitable for high-gain applications, such as EVs. The proposed converter uses fewer number of switches to provide high step-up and high step-down voltage converting capabilities in both power flow directions. Since the input and output of this converter share the same ground, the electromagnetic interface is alleviated. In order to assess the versatility of the proposed dc–dc converter and to achieve a fast response, by equipping this converter with an input–output feedback linearization (IOFL) controller, its performance is analyzed in EV applications. To this end, the steady-state calculations are worked out for both charge and discharge directions, then dynamic analysis and control design are presented based on nonlinear controller by IOFL. Simulation and experimental results are provided to prove the feasibility of the proposed converter.

This paper proposes a 1-ϕ transformer-less inverter for grid-tied PV systems. The proposed inverter has the capability to produce five distinct voltage levels at the output stage. Moreover, it is a compact switched-capacitor (SC) based design that incorporates eight power switches, an ultra-fast power diode, and two electrolytic SCs. This topology reduces the number of power electronic components, resulting in decreased cost and weight. Due to the direct connection of the negative dc line of the proposed inverter to the null of the grid voltage, the leakage current is completely removed for PV application. Another advantage of this topology is that it can easily boost the output voltage by a factor of two without the need for any magnetic or active devices. During the grid voltage period, the SC's are charged in series with the input voltage, resulting in automatic balancing. As a result, the proposed inverter eliminates the need for a complex control method to balance the SC's. Design guidelines have been developed for the proposed inverter. Also, the quantitative comparative study with similar five-level topologies is presented to show superiority of the proposed inverter. Moreover, the proposed inverter alongside a PV system is simulated to demonstrate the capability of the proposed inverter in a closed-loop D-Q control system. This topology is validated using a laboratory prototype for a 1 kW system at a grid-tied connection.

This paper presents a novel single-phase inverter with six switches and five levels that shares a common ground and does not require a transformer. The proposed inverter is intended for use in photovoltaic systems that are connected to the grid. The proposed inverter is derived from the concept of a capacitive voltage divider (CVD) circuit, so that, the leakage current will be eliminated. The CVD circuit produces three levels of output voltages in the proposed inverter. The proposed novel inverter has several significant advantages, such as the elimination of leakage current without the need for additional components, the ability to transfer reactive power fully, and the use of fewer components compared to current five-level transformer-less inverters. Additionally, the voltage stress is evenly distributed across power switches, resulting in higher efficiency. Furthermore, the inverter is designed to automatically balance voltage in capacitors without requiring an additional control system. The proposed inverter achieves these advantages using a suitable switching scheme. The paper also includes an explanation of the proposed circuit, the process for designing minimum capacitors, theoretical loss calculation, and a comparison of features with similar topologies todemonstrate the efficiency of the proposedinverter. Inaddition, a 1 kVA experimental prototype is constructed to showcase the effectiveness of the proposed inverter.

In this article, a new inverter unit is proposed. It is a compact switched-capacitor-based inverter, which is combined of four switches, two diodes, and four capacitors. Since this inverter unit is a mid-point-clamped inverter, it can mitigate the capacitive leakage current in many applications. One of the main applications of the proposed inverter is in grid-tied photovoltaic systems, where the common-mode current brings many challenges. Other than the mentioned feature, the proposed inverter includes the following advantages: 1) spontaneous balancing of the voltage across the capacitors without needing any control system or auxiliary circuits; 2) capability of full reactive power transfer; 3) low voltage stress on the capacitors compared to common three-level inverter topologies (NPC, T-type-NPC, FC, etc.); and 4) symmetric switching sequence, which causes a continuous input current. The feasibility and versatility of the proposed inverter unit is validated by experimental tests, which are conducted by using a lab-scale prototype.

This paper introduces a new single phase transformerless photovoltaic (PV) inverter for grid connected PV systems using the concept of a charge pump. It consists of four power switches, two diodes, two capacitors and an LC filter at the output stage. The neutral of the grid is directly connected to the negative terminal of PV panel. This common ground creates a constant Common Mode (CM) voltage and zero leakage current. Meanwhile, the charge pump circuit generates the negative bus voltage for the inverter during the negative power cycle. A unipolar Sinusoidal Pulse Width Modulation (SPWM) technique is applied to the proposed inverter with three level output voltage to reduce the output current ripple and the filter requirements. The main advantages of the proposed inverter are (1) the negative polarity of the PV is directly connected to the grid, so the leakage current eliminated, (2) it has a compact size, (3) peak of output voltage is equal to input dc voltage (unlike Neutral Point Clamped (NPC) inverter, Active NPC (ANPC) and some topologies, which requires two times of the peak ac-voltage magnitude), flexible grounding configuration and high efficiency. The operating principle and analysis of the proposed topology are presented in details. Experimental results of a 500 W prototype are demonstrated to validate the proposed topology and the overall concept. The obtained results clearly verify the performance of the proposed inverter and its practical application for grid connected PV systems.