Zhixiang Yu

Bio: Zhixiang Yu is an academic researcher from Anhui University of Technology. The author has contributed to research in topics: Inverter & Capacitor. The author has an hindex of 2, co-authored 4 publications receiving 11 citations.

A Hybrid Cascaded High Step-Up DC–DC Converter With Ultralow Voltage Stress

Abstract: A novel hybrid cascaded dc–dc converter is proposed for high voltage gain applications in this article, which is characterized by the hybrid series-parallel connection based on coupled inductors and voltage multiplier cells. The input current ripple is decreased due to the interleaved operation and the voltage stress of the switches is only 1/6 of the output voltage when the turn ratio is 1. So the high-performance MOSFETs with low ON-state resistance can be used to reduce the conduction losses. The reverse-recovery problem of the output diode can be suppressed by the leakage inductance of the coupled inductors. The leakage inductance energy of the coupled inductors is absorbed and recycled to the output, which can largely improve the efficiency of the proposed converter. The working principle and steady-state characteristics of the converter are analyzed in detail. Finally, the correctness of the theoretical analysis is verified through experimental results of a 400-W laboratory prototype.

A Transformerless Boost Inverter for Stand-alone Photovoltaic Generation Systems

Abstract: a novel transformerless boost inverter for standalone photovoltaic generation systems is proposed in this paper. The proposed inverter combines the boost converter with the traditional bridge inverter. The switch S1 can not only realize the boost function but also participate in inverting process. The inverter has a higher voltage gain and good characteristics when the inductor L 1 is operated in discontinuous mode (DCM) and the nonpolarized capacitor can be chosen as bus capacitor, which makes the volume smaller and the service life of the inverter is increased. The inverter consists of five switches in which only two switches are operated at high frequency state and a monopole SPWM strategy is used. Therefore, the modulation strategy of switches is very simple and the switching loss is reduced. The principle of inverter is described in detail and the correctness of the theoretical analysis is verified by simulation and experiment.

Converter and modulation method thereof

Abstract: The invention discloses a converter and a modulation method thereof, and belongs to the technical field of power electronic converters. One end of the DC side of the converter is connected with one end of an inductor Lin, the other end of the inductor Lin is connected with a terminal 1 of a power switch transistor S1 and a conduction end of a switching device, a cut-off end of the switching deviceis connected with terminals 1 of power switch transistors S2, S4 and one end of a capacitor C1, the other end of the capacitor C1 is connected with terminals 2 of power switch transistors S3, S5, theother end of the DC side of the converter, terminals 2 of the power switch transistors S1, S2, a terminal 1 of the power switch transistor S3 and one end of the AC side are all grounded, a terminal 1of the power switch transistor S5 and a terminal 2 of the power switch transistor S4 are connected at the other end of the AC side. In addition, the invention further provides a corresponding modulation method, a bidirectional converter and a corresponding modulation method thereof. In allusion to a problem of high-frequency leakage current existing in the traditional boost inverter, the converter disclosed by the invention has the advantages of high integration degree and small volume and can effectively solve the problem of high-frequency leakage current.

A Three-Winding Coupled Inductor-Based Interleaved High-Voltage Gain DC–DC Converter for Photovoltaic Systems

Abstract: In this article, an interleaved high-voltage gain dc–dc converter is proposed for use with photovoltaic (PV) systems. By integrating two three-winding coupled inductors (CIs) with switched capacitor cells, the voltage gain is further extended. Through passive diode-capacitor clamp circuits, the energy stored in the leakage inductances is absorbed; additionally, the voltage stress of the power switches is clamped to a value far lower than the output voltage, which enables designers to select switches with low-voltage ratings. Due to the interleaved structure of the proposed converter, the input current has a small ripple, which leads to the increased lifespan of the PV panels. In addition, the current stress on the components is reduced. Thanks to the leakage inductances of the CIs, the zero-current switching condition is intrinsically provided for the diodes; accordingly, the adverse impact of the diodes’ reverse-recovery is alleviated. The operating principles, steady-state analyses, and design considerations of the proposed converter are presented in this article. A comparison with other similar converters is carried out to verify the merits of the proposed converter. Finally, the theoretical analyses are confirmed through the experimental results of a 400-W prototype with an output voltage of 400 V.

A High Step-Up Z-Source DC-DC Converter for Integration of Photovoltaic Panels into DC Microgrid

Abstract: This paper presents a Z-source-based high step-up DC-DC converter that benefits from high voltage gain, low voltage stress on the semiconductor devices and the capacitors. The switched-capacitor cells are integrated with the conventional Z-source impedance network resulting in a new high step-up DC-DC converter. The proposed converter is suitable for photovoltaic (PV) applications where PV panels are linked to a 400 V DC bus in a DC microgrid. The proposed converter reduces the voltage stress on the diodes and the power switch to less than half the output voltage and achieves a high-voltage gain without imposing a limitation on the duty cycle and requiring a large number of components. The operating principles, the steady-state analysis, and a comparison with other similar high step-up DC-DC converters are presented. The simulation and experimental results validate the performance and the applicability of the proposed converter.

A Three-Winding Coupled Inductor-Based Interleaved High-Voltage Gain DC–DC Converter for Photovoltaic Systems

Abstract: In this article, an interleaved high-voltage gain dc–dc converter is proposed for use with photovoltaic (PV) systems. By integrating two three-winding coupled inductors (CIs) with switched capacitor cells, the voltage gain is further extended. Through passive diode-capacitor clamp circuits, the energy stored in the leakage inductances is absorbed; additionally, the voltage stress of the power switches is clamped to a value far lower than the output voltage, which enables designers to select switches with low-voltage ratings. Due to the interleaved structure of the proposed converter, the input current has a small ripple, which leads to the increased lifespan of the PV panels. In addition, the current stress on the components is reduced. Thanks to the leakage inductances of the CIs, the zero-current switching condition is intrinsically provided for the diodes; accordingly, the adverse impact of the diodes’ reverse-recovery is alleviated. The operating principles, steady-state analyses, and design considerations of the proposed converter are presented in this article. A comparison with other similar converters is carried out to verify the merits of the proposed converter. Finally, the theoretical analyses are confirmed through the experimental results of a 400-W prototype with an output voltage of 400 V.

Analysis and Design of a Transformerless Boost Inverter for Stand-Alone Photovoltaic Generation Systems

Abstract: A novel transformerless boost inverter for standalone photovoltaic generation systems is proposed in this paper. The proposed inverter combines the boost converter with the traditional bridge inverter. The switch S1 not only realizes the boost function but also participates in inverting process. The inverter has a higher voltage gain and good characteristics when the inductor L1 is operated in discontinuous mode (DCM) and the nonpolarized capacitor can be chosen as bus capacitor, which makes the volume smaller and the service life of the inverter is increased. The inverter consists of five switches in which only two switches are operated at high frequency state and a monopole sinusoidal pulse width modulation (SPWM) strategy is used. Therefore, the modulation strategy of switches is very simple and the switching loss is reduced. The principle of inverter is described in detail and mathematical models are built by small-signal analysis. Finally, the correctness of the theoretical analysis is verified by simulation and experiment.