Dual Buck Half Bridge Inverter Research Articles

Transformerless Grid-Connected PV Inverter Without Common Mode Leakage Current and Shoot-Through Problems

As there is shoot-through problem and common mode leakage current in conventional transformerless grid-connected PV inverters, a transformerless grid-connected PV inverter without common mode leakage current and shoot-through problems is proposed. The proposed inverter consists of a buck-boost converter and a dual-buck half-bridge inverter, so there is no shoot-through problem in the proposed inverter. As grounds of the input source and the grid are shorted, there is no common mode leakage current. No current flows through the body diodes of switches, so efficiency of the system is improved. Operating principle of the proposed inverter is elaborated in detail. Experimental results of a 350 W proposed inverter validate the theoretical analysis.

Non‐circulating‐current magnetic‐integrated three‐bridge dual‐buck inverter

A novel non-circulating-current magnetic-integrated three-bridge dual-buck inverter (DBI) is proposed. By adding the third bridge, the proposed inverter can remove two input capacitances and enhance the utilisation of input voltage in traditional dual buck half-bridge inverter (DBHBI). In addition, the partly coupled inductors with non-dotted ends connected are applied to elevate the power density. The dc link diode is utilised to eliminate circulating current caused by magnetic induction absolutely. The generating principle of circulating current and operating principle of the proposed inverter have been analysed in detail. Finally, experimental results are obtained on a 1 kW prototype to verify the practical application of the proposed inverter.

Modelling and control of a novel zero‐current‐switching inverter with sinusoidal current output

This study presents a novel topology of charge-transferring zero-current-switching (CT-ZCS) inverter to improve the efficiency. Its operating principle, optimal zero-current-switching (ZCS) frequency and design guidelines are elucidated in detail. A reduced-order modelling method of time-charge discretisation, which treats a set of two separate ZCS as one combined switch cell, is put forward and the topology can be simplified to dual-buck half-bridge inverter (DBHBI) topology. Since the DBHBI-derived CT-ZCS inverter permits higher comparison frequency of hysteresis control than traditional hard-switching inverters, the three-level relay control with high-frequency pulse modulation is recommended. Compared with two-level and three-level hysteresis control, the proposed control can achieve effective output harmonic reduction, decreasing from 2.335 to 1.66%, and minimise the size of inverter under the same output condition. In addition, a current controller is designed to optimise the system and enhance its anti-disturbance performance. Finally, the experiment on a 35-V 2-A prototype verifies the validity of the proposed method.

Three‐bridge buck inverter

On the basis of dual-buck half-bridge inverter, a three-bridge buck inverter is proposed, which not only remains the advantages of dual-buck half-bridge inverter, but also improves the inverter's performance such as avoids shoot-through problem, removes the reverse recovery losses of body diodes and so on. By adding a new bridge, the three-level modulation and the single power supply are realised, which increase the DC voltage utilisation rate. In addition, smaller volume and weight of the system and higher system integration can be achieved using only one filter inductor compared with other dual-buck-type inverters. The unipolar sinusoidal pulse width modulation scheme is adopted in the inverter system, so the switching frequency is fixed, which is beneficial to the design of filter. The operating principle and characteristics of the proposed inverter are analysed in detail. A 1 kW prototype is established and tested, and the results of simulation and experiment verify the good performance of the proposed inverter.

Simulation Analysis of Improved Construction and Control Strategy for Programmable AC Power Source

Novel circuit topology and advanced control technique of inverter are research focus for programmable AC power source. An improved dual buck half bridge inverter topology is introduced and the central symmetrical pulse width modulation mode is proposed to double the output current ripple frequency. High output precision can be achieved by optimizing the output waveforms of inverter. Then, a hybrid digital control scheme combining PID control with repetitive control as well as inductance compensation deadbeat control is presented for the closed loop voltage regulation of the mentioned inverter. Besides, an inductance saturation characteristic mathematic model is established for accurate simulation. Simulation results show that the theoretical analysis of the special switching sequence and hybrid control scheme is true.

A Family of Five-Level Dual-Buck Full-Bridge Inverters for Grid-tied Applications

Dual-buck inverters feature some attractive merits, such as no reverse recovery issues of the body diodes and free of shoot-through. However, since the filter inductors of dual-buck inverters operate at each half cycle of the utility grid alternately, the inductor capacity of dual-buck inverters is twice as much as H-bridge inverters. Thus, the power density of dual-buck converters needs to be improved, as well as the conversion efficiency. In this paper, the detailed derivation process of two five-level full-bridge topology generation rules are presented and explained. One is the combination of a conventional three-level full-bridge inverter, a two-level capacitive voltage divider, and a neutral point clamped branch. The other method is to combine a three-level half-bridge inverter and a two-level half-bridge inverter. Furthermore, in order to enhance the reliability of existing five-level DBFBI topologies, an extended five-level DBFBI topology generation method is proposed. The two-level half-bridge inverter is replaced by a two-level dual-buck half-bridge inverter; thus, a family of five-level DBFBI topologies with high reliability is proposed. The operation modes, modulation methods, and control strategies of the series-switch five-level DBFBI topology are analyzed in detail. The power device losses of the three-level DBFBI topology and five-level DBFBI topologies, with different switching frequencies, are calculated and compared. Both the relationship between the neutral point potential self-balancing and the modulation index of inverters are revealed. A universal prototype was built up for the experimental tests of the three-level DBFBI topology, the five-level H-bridge inverter topology, and the existing three five-level DBFBI topologies. Experimental results have shown that the five-level DBFBI topologies exhibit higher efficiency than the five-level H-bridge inverter topology and the three-level DBFBI topology. As well, the higher power density has been achieved by the five-level DBFBI topologies compared with the three-level DBFBI topology.

A Cascaded Dual Buck Half-Bridge Inverter for Efficient Power Flow Control in Grid

This paper presents a single phase 7-level half bridge cascade dual buck multilevel grid-tied inverter with both active and reactive power flow control in a wide range under two types of renewable energy. The power flow is controlled by varying the switching pulse of the power semiconductor device used in the half bridge cascade dual buck multilevel grid-tie inverter. The multicarrier sinusoidal pulse width modulation (SPWM) is used by which the power angle can be varied, by changing the switching pulse. By varying the power angle, the voltage and current at the grid side is changed. Active and Reactive power consumed or injected by each unit is depending on the shift angle between the current and modulated voltage in the each single unit of cascade dual buck inverter. Thus by varying the power angle, the power flow can be controlled effectively. The Total Harmonic Distortion (THD) is reduced, when compared with the 11-level cascade H-bridge grid-tie inverter. This is proved by using FFT analysis in MATLAB SIMULINK. The simulation is carried out for both type I and type II system in MATLAB SIMULINK. The experimental results have proved the effectiveness of the designed grid-tie control for both type I and type II system.

Transformerless Split-Inductor Neutral Point Clamped Three-Level PV Grid-Connected Inverter

Characterized by low leakage current and low voltage stress of the power device, a neutral point clamped three-level inverter (NPCTLI) is suitable for a transformerless photovoltaic (PV) grid-connected system. Unfortunately, the shoot-through problem of bridge legs still exists in an NPCTLI, so its operation reliability is degraded. An improved three-level grid-connected inverter is proposed based on the NPCTLI and the dual-buck half-bridge inverter (DBHBI), and which avoids the shoot-through problem. The proposed topology guarantees no switching-frequency common-mode voltage and no shoot-through risk. Furthermore, the freewheeling diode of bridge legs of the DBHBI can be removed taking into consideration the unity power factor of grid current, and a straightforward topology is thus derived. The new topology is referred to as split-inductor NPCTLI (SI-NPCTLI). The operation mode, common-mode characteristic, and control strategy are analyzed. Finally, both the simulation and the experimental results of a 1-kW SI-NPCTLI prototype verify the analysis.

A SPWM Control Method for Dual Buck Half Bridge Inverter Based on the Direction of Inductor Current

The Dual Buck Half Bridge inverter has been widely researched because of no bridge arm shoot-through problem and higher efficiency. Because the switch frequency always varies, the output filter parameters are very difficult to optimally design by using hysteresis current control. In this paper, a SPWM control method is proposed. The control method not only can be easy realized, but also get the no-biased current model. Finally, the proposed SPWM control method is verified by the simulation and experiment results.

Research on Dual Buck Half Bridge Five-Level Inverter for Rooftop Solar System

This paper presents a novel design for dual buck half bridge five-level inverter (DBHBFLI), which based on field-programmable gate array (FPGA), and was used for photovoltaic power system. This topology is derived from dual buck half bridge inverter (DBHBI), which has the characteristics of no shoot-through problem, no body diode reverse-recovery problem, and current half-period work mode, these merits are retained in the proposed inverter. FPGA logic device is chosen for the hardware implementation of control circuit. The FPGA controller consists of six main modules: the sine wave generator module, the triangle wave generator module, the voltage proportion integration (PI) module, the current proportion (P) module, sinusoidal pulse width modulation (SPWM) module, and SPWM distribution module. VHDL is used in the design of each module. The simulation and experiment results which confirm the validity and performance of the design are shown in the paper.

Dual-Buck Full-Bridge Inverter With Hysteresis Current Control

This paper presents a dual-buck full-bridge inverter (DBFBI) to solve the shoot-through problem in conventional bridge-type inverters and reduce the voltage stress of the power device in the dual-buck half-bridge inverter (DBHBI). Hysteresis current control is used in the DBFBI. All switches and diodes operate at each half line cycle, and the freewheeling current flows through the independent freewheeling diodes instead of the body diodes of the switches, so the efficiency can be increased potentially. As the shoot-through problem does not exist in the DBFBI, dead time between the switches need not be set. The input-voltage utilization rate of the DBFBI is twice that of the DBHBI under the same output-voltage condition, i.e., the voltage stress of the power device in DBFBI is half that in the DBHBI. The operating principle, stability and relative stability analyses, and design guidelines and example are provided. Experimental results of a 1-kVA DBFBI verify the theoretical analysis. The comparisons among other inverters and the DBFBI show that the proposed inverter is very promising in 220-240-V <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">rms</sub> output-voltage and high-reliability applications, such as uninterruptible power supplies and grid-connected inverters.