Wenxun Xiao

A Z-Source Half-Bridge Converter

Applying an LC network into a half-bridge converter, a novel Z-source half-bridge converter is presented, in which less LC components are needed compared to the conventional one. This Z-source half-bridge converter can solve not only the problems of the shoot-through and limited voltage but also the problem of imbalance at the midpoint voltage of input capacitors. Furthermore, it can generate a broader range of output voltage values and much more kinds of waveforms, such as the varied positive or negative output voltages and the varied time ratio between positive and negative voltages, which are particularly desirable for some special power supplies, like the electrochemical power supply. Finally, the proposed converter is implemented in a prototype, and the experimental results can verify the effectiveness of the proposed converter.

Analysis and Design of an Automatic-Current-Sharing Control Based on Average-Current Mode for Parallel Boost Converters

This paper presents an automatic-current-sharing control method based on average-current mode for parallel boost converters. With the proposed method, the second-order system of the external loop of boost converter is reduced to a first-order in low frequency, which makes the design of the control circuit easy and improves the dynamic response of parallel boost converters. This paper presents detail analysis and improved design guidelines for the proposed control system. The multi-module parallel number is limitless in theory. Two 40 V/120 V/4.2 A boost converters have been designed for parallel experiment, verifying the correctness of the theory analysis

Control Strategy Based on Discrete-Time Lyapunov Theory for DC-DC Converters

This paper presents switched linear systems (SLS) model for DC-DC converters, and investigates the limit cycle existence and stability problems of SLS. By utilizing multiple-Lyapunov function, the sufficient condition of exponential stability and convergent rate in the form of linear matrix inequalities (LMIs) for SLS are developed. Combining limit cycle existence and LMIs formulation, the switching laws are designed such that the closed-loop system can be operated stably. At last, the design method for the control strategy of SLS in DC-DC converters is considered. The simulation results validate the effectiveness of the design method. The results in this paper offer a theory basis for the application of the SLS control theory on DC-DC converters.

A modified Z-source DC-DC converter

A modified Z-source dc-dc converter is proposed in this paper. Compared with the conventional Z-source dc-dc converter, the proposed converter can obtain higher voltage gain with lower voltage stresses of switch and the impedance network capacitor and operate with wide-range load. Therefore, the proposed Z-source dc-dc converter not only has lower cost but also has smaller weight and size. The operating principle is analyzed in detail and parameter design of the impedance network is introduced. An experimental prototype was built to verify the validity of the proposed Z-source dc-dc converter.

A single-switch high step-up DC-DC converter with coupled inductor

With the development of photovoltaic (PV), fuel cells and uninterruptible power supply (UPS), high step-up converter plays an important role in them. In this paper, a single switch high step-up DC-DC converter is proposed, which can achieve high voltage gain without extreme duty cycle and huge turn ratios of coupled inductor. The leakage energy of coupled inductor can be recycled and the voltage across the switch can be clamped. Moreover, the reverse recovery of some diodes can be reduced. All these characteristics make it possible to design appropriate parameters to realize high step-up gain and high efficiency. The operating mode, static analysis and simulation results have been presented, and a prototype circuit has been realized to verify the effectiveness of the proposed converter.

A novel single-switch cascaded DC-DC converter of Boost and Buck-boost converters

This paper proposes a novel single-switch dc-dc converter with voltage gain D/(1-D)2 by cascading a Boost converter and a Buck-boost converter. The proposed converter has the advantages of simple circuit structure and extended voltage conversion ratio. The operating principle and steady-state analysis of the proposed converter are discussed in detail. Finally, a prototype is implemented to verify theoretical analysis.

A quasi-Z-source DC-DC converter

A novel quasi-Z-source dc-dc converter is proposed in this paper. Compared with the conventional Z-source dc-dc converter, the proposed converter features high voltage gain with lower voltage stress of the impedance network capacitors and has common ground for input and output. Moreover, both the input source current and output load current of the proposed converter are continuous, which provides advantage for input and output filtering. Therefore, the proposed converter has lower cost and better performance. The circuit analysis of the proposed converter is illustrated in detail and the parameter design is introduced. Finally, simulation and experimental results are presented to verify the validity of proposed converter.

Phase-modular three-phase isolated bridgeless PFC converter

On the basis of summarizing the advantages and disadvantages of present phase-modular three-phase power factor correction (PFC) converters, this paper proposes the phase-modular three-phase isolated bridgeless Sepic and Cuk PFC converter. The proposed converters are implemented by star connection of single-phase isolated bridgeless Sepic and Cuk PFC converter. The proposed converters not only can reduce the conduction losses caused by rectifier diodes, but also can achieve zero voltage switching. Additionally, the proposed converters only use a simple control loop to regulate the output voltage and make the input current in phase with the input voltage in DCM, which sufficiently reduces the complexity of control strategy. Due to the same behavior of two proposed converter, only the detailed operating principle, simulation and experimental results of the phase-modular three-phase isolated bridgeless Sepic PFC converter are given.

A bridgeless PFC converter with high efficiency and universal input voltage range

In this paper, a bridgeless PFC converter in which two diodes in the rectifier-bridge are replaced by two switches is proposed, and its operating principles in both continuous conduction mode (CCM) and discontinuous conduction mode (DCM) are analyzed in detailed. The simulation results verify the theoretical analysis. Compared to other bridgeless PFC converter, the proposed converter has lower voltage stress, higher static gain and is more suitable for the universal input voltage application.