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POWER ELECTRONICS 2018 PROJECTS

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A Family of PWM Control Strategies for Single-Phase Quasi-Switched-Boost Inverter

Abstract:

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.

Modified L-Z-source inverter with high gain inversion and inductive load compatibility

Abstract:

This paper proposes a modified L-Z-source inverter (L-ZSI), which is derived from L-ZSI with addition of few more elements to overcome the limitations of L-ZSI. The modified L-ZSI gives higher boosting capability at low shoot-through duty ratio and improved AC output voltage at reduced harmonic distortions unlike conventional L-ZSI. Due to its higher boosting capability at low duty ratio, it is appropriate to connect low input voltage sources to grid or standalone systems at reduced harmonic distortions. Detailed mathematical modelling is carried out and a scaled down laboratory prototype is developed to verify the performance of the proposed inverter.

New interleaved single-phase quasi-Z-source inverter with active power decoupling

Abstract:

This paper is devoted to a new topology of a single-phase interleaved quasi-z-source inverter with active power decoupling circuit. The inverter comprises two classical completely interleaved quasi-z-source inverters to gain the benefits of passive component reduction and power quality improvement. The modulation technique applied allows maximum boost control for better utilization of the dc-link. At the same time, the input power ripple was significantly reduced. Due to the applied approach, total requirements for capacitive energy storage were decreased by 37 times as compared to the simple boost and maximum boost control without active power decoupling. As a result, the quasi-z-source stage capacitance was reduced while the output power quality was kept high. The proposed topology is ideally suitable for standalone and grid-connected single-phase photovoltaic applications.

New switching technique for quasi-Z-source resonant converter

Abstract:

The Quasi-Z-Source (QZS) inverters are the promising topology for the renewable integration with the grid. QZSI achieves the MPPT during the shoot through state, without additional DC-DC converter, and simultaneously delivering the AC power to the grid or motor load. The quasi components (L and C) sizes are reduced by increasing the switching frequency of the converters. But the switching losses of the converter will dominate at the higher frequencies. To minimize the switching losses of the converter, this paper proposes reduced switching loss single stage inverter for high power applications. Using only six devices rated at supply voltage, the QZS resonant converter can operate properly by adding resonant inductor and capacitor to the ac side of each phase. The proposed converter can control the output with true pulse width modulation (PWM) at high frequency and the Zero Voltage Switching (ZVS) and Zero Current Switching is achieved at every switching cycle. The detailed analysis, modulation and simulation are presented to verify the operating principle of the QZS resonant converter.

Design of SiC-based single-phase quasi-Z-source inverter

Abstract:

Silicon Carbide (SiC)-based single-phase quasi-Z-source inverter (qZSI) is proposed in this paper to provide a high power density and cost benefit solution for the Photovoltaic (PV) power application. Bulky qZS impedance network is unavoidable in conventional single-phase qZSI even with SiC power devices, due to handling double-line-frequency (2ω) ripple. The design of SiC-based single-phase qZSI is addressed in this paper through power loss evaluation and impedance parameters determination with active power filter’s phase leg for compensting the 2ω ripple. All passive components are small in size and weight under the high switching frequency of SiC devices. Power devices’ losses of SiC and Si-based inverter are compared. Simulation results at the designed parameters are introduced to validate the proposed solution.

Efficiency and loss distribution analysis of the 3L-Active NPC qZS inverter

Abstract:

Quasi-Z-source (qZS) inverters have been found very suitable in boost operation applications. As a result, studies have focused on the three-level neutral-point-clamped (3L-NPC) qZS inverters. However, this topology has a shortcoming of loss distribution among the switches. Focus in this article is on the application of the 3L-Active NPC (3L-ANPC) to the qZS inverters. Our study will show the impact of this topology on the efficiency of the system as well as on the distribution of the switching losses. A shoot-through sinusoidal pulse with modulation adapted to the 3L-ANPC was used. A modified modulation was also implemented and tested. Several simulation tests were performed to analyze the adopted topology and modulation strategies.

Single-phase qZS-based PV inverter with integrated battery storage for distributed energy generation

Abstract:

This paper presents an experimental setup of quasi-Z-source-based inverter for photovoltaic application solution with storage integration. It fully describes the industrial prototype experimental setup considering its complete functionalities. The specifications of this system were made taking into consideration the context of smart-grids and the support of low voltage networks. Experimental results are presented. The main pros and cons are discussed.

An energy stored improved Y-source single-phase inverter for photovoltaic system applications

Abstract:

The family of Z-source inverters (ZSI) equipped with battery are able to balance probable fluctuations of photovoltaic (PV) power injected into the grid/load, but their existing topologies have voltage gain limitations, draw discontinuous current from PV panels, and need to use higher battery capacity and PV voltage. This paper proposes a new single-phase topology called Battery Energy Storage Improved Y-Source Inverter (BES-IYSI) to overcome these disadvantages. The operating principles of the proposed topology is analyzed in detail and compared to the existing topologies. In addition, a control scheme is proposed in order to extract maximum power from PV panels, control the injected power into the grid, and manage the power of resources. Simulation results are also presented using the MATLAB/Simulink software, which show the performance of the proposed system.

High efficiency operation control of quasi-Z-source based permanent magnetic synchronous motor drive

Abstract:

In recent years, with the research of indirect matrix converter (IMC) and Z-source / quasi-Z-source (ZS/QZS) boost converters proposed, the relevant scholars combine the two and put forward the QZS-IMC. The topology can greatly expand the voltage gain range, and enhance the anti-interference capability, especially the ability to ride through the grid voltage sag. It has been proved to be a promising converter. However, the research and application of the new converter is still in the exploration stage, and it lacks of in-depth analysis and control. In this paper, the optimal operation control of QZS-IMC is studied and proposed for the QZS-IMC motor drive system, to fulfill high efficiency. Simulation results show that after the drop of input voltage, the system can automatically and optimally regulate the output voltage through optimization of D, so as to improve the performance of IMC in the field of AC speed regulation, and better promote the IMC circuit and QZS circuit to be practical.

Integrated Dual Output L-Z Source Inverter for Hybrid Electric Vehicle

Abstract:

A single stage converter, simultaneously supplying the power to DC and AC load is an interesting solution. Cost saving, better efficiency and independent control of both outputs(in restricted range) is the key feature achieved in a single stage converter. Switched boost, Boost, and LZSI derived hybrid converter are the potential solutions reported in literature. These converters have restricted range of controlling the output voltage independently. To widen the range of independent control, this paper presents a three winding mutual coupled inductor based L-Z source inverter(MCL-ZSI). Initially, this topology is developed as dc-dc converter which is further extended for hybrid output applications. Though the duty cycle is varied in the range of 0 < D < 1, the gain achieved using this topology is higher than its counterparts. The gain of proposed inverter is derived analytically and validated experimentally. To investigate the characteristics of the inverter, the open loop transfer function is derived which is further utilized to design the closed loop control. The theoretical design of closed loop is validated experimentally.

Encoder-less speed control of PMSM drive using adaptive observer

Abstract:

This paper mainly focuses on the full order state observer for the vector control (field-oriented control) of a surface mounted Permanent Magnet Synchronous Motor (PMSM) without the use of a speed sensor. Space Vector Pulse Width Modulation (SVPWM) technique has been used to generate three phase voltages from the dc link source. The inverter switches are designed here with no dead time compensation. The rotor speed is treated as an unknown parameter and the adaptation law for driving the estimated rotor speed is being carried out by the use of Popov’s Hyper stability criteria. The proposed observer and the whole other system except the PWM generation block and the PMSM has been discretized i.e., the whole system is running at a variable sampling rate and rate transitions blocks have been used to make the bridges between the continuous and discrete subsystems. For making the observer to become dynamically faster the observer poles are fixed proportionally to its motor poles using pole placement technique. The whole system is being verified using MATLAB/Simulink environment.

IGBT Open-Circuit Fault Diagnosis in a Quasi-Z-Source Inverter

Abstract:

In this paper, a fast and practical method is proposed for open-circuit (OC) fault diagnosis (FD) in a three-phase quasi-Z-source inverter (q-ZSI). Compared to the existing fast OC FD techniques in three-phase voltage-source inverters (VSIs), this method is more cost-effective since no ultra-fast processor or high-speed measurement is required. Additionally, the method is independent of the load condition. The proposed method is only applicable to Z-source family inverters and is based on observing the effect of shoot-through (SH) intervals on the system variables during switching periods. The proposed algorithm includes two consecutive stages: OC detection and fault location identification. When both stages of the OC FD algorithm are done, a redundant leg is activated and utilized instead of the failed leg. The accuracy of the proposed method is confirmed by the experimental results from a low-voltage q-ZSI prototype.

Single-Phase Z-Source\/Quasi-Z-Source Inverters and Converters: An Overview of Double-Line-Frequency Power-Decoupling Methods and Perspectives

Abstract:

In this article, we investigate power-decoupling methods used in single-phase Z-source/quasi-Z-source inverters (ZSIs/qZSIs) to handle inherent double-linefrequency (2ω) power by comparing their implementation approaches and performances. Passive methods can be used to suppress 2ω ripples within the range of engineering tolerance by designing impedance networks, modifying modulation methods, or using closed-loop damping controls. Active power-decoupling methods eliminate 2ω ripples from the dc side by employing an active filter that buffers the 2ω ripple power. After we address the pros and cons of all methods, we apply a typical active method to a single-phase qZSI and a single-phase qZS matrix converter to demonstrate their high performance, promising perspectives, and potential applications.

A control method of three-phase Z-source integrated charger with motor windings

Abstract:

The driving system and the charging system of a electric vehicle cannot work simultaneously. The charging system shuts down when a electric vehicle is running and the driving system shut down when a electric vehicle is being charged. Therefore, the power converter of driving system can be used as a rectifier module to reduce the volume, weight and cost of a electric vehicle. Three-phase Z-source converter is researched in this paper, as it can not only drive motors in inverter mode but can also charge the battery in rectifier mode. In the three-phase Z-source charger, the range of output voltage is wider due to its Buck characteristic. In order to enhancing the integration level of the driving system and charging system, connection type of motor windings is modified to replace the filter inductors in the three-phase Z-source integrated charger. A charging control method is proposed and experimental platform is built to verify this method.

PMSM driving system design for electric vehicle applications based on bi-directional quasi-Z-source inverter

Abstract:

When operating up the base speed, permanent magnet synchronous motor(PMSM) is usually controlled by flux-weakening methods, which is realized by generating d-axis demagnetization current and then lowers the system efficiency. Limited by inverter voltage and current level, the motor output power has also been limited. In this paper, we proposed a bus voltage variable PMSM drive system based on quasi-Z-source, expecting to improve the system efficiency. Experimental results prove the feasibility of this scheme.

Control strategy for parallel-connected three-phase inverters

Abstract:

In this paper, a control strategy for parallel connected three-phase voltage source inverters is presented. The control strategy is based on the droop control method, which does not require interconnection and communication between individual inverters of parallel connected system. In each of the parallel connected inverters, the inner control structure in Direct-Quadrature (DQ) rotating frame is used. The outer control loop ensures appropriate loads sharing. The whole control system is described, and dynamic and static behavior is verified by simulations.

Control of a three-port DC-DC converter for grid connected PV-battery applications

Abstract:

A control strategy for an energy management system (EMS) of a household nanogrid is presented in this paper. The proposed EMS is based on a state diagram. A three port converter (TPC) with direct storage capability is chosen and the states together with the state transitions are defined. The state diagram signals to two algorithms of which one calculates the battery current reference and the other allows the photovoltaic (PV) system to operate at the maximum power point (MPP) at all times. An extensive model has been implemented in MATLAB/Simulink using generic models to test the proposed control method. Results show a system which at all times follows a specified power exchange with the grid with a overshoot in power of 500W and worst case settling time of 500ms.

Design of wide input voltage range high step-up DC-DC converter based on secondary-side resonant tank full bridge LLC

Abstract:

Battery are widely utilized in uninterruptible power supply (UPS) to provide the power temporarily during power failure. In applications up to a few kilo watts, low voltage battery stack are typically used since it is not economically feasible to use high voltage battery stack in such application. To interface the battery to the dc-link of the UPS, power electronic converter are widely used. Due to the wide voltage variation at battery terminal that are mainly caused by battery state of charge and battery stack current, power converter for battery application are required to be capable to interface with wide battery voltage range. In this paper, a wide input range high step up converter was designed based on LLC converter. To significantly reduce the resonant capacitor current, secondary side resonant tank LLC converter was proposed. Finally, a 2 kW prototype was designed for 36 V~ 72 V input voltage and 410 V output voltage, built, and from experimental test 93.59% peak efficiency was measured.

Performance improvement for DC boost converter with fuzzy controller

Abstract:

This paper presents the improved performance of a fuzzy PD controller than a conventional PD controller to control DC-DC Converter. The experimentation in fuzzy domain using five and seven membership functions with the proposed input and output variables. A fuzzy controller can be implemented where linear control techniques fail. The experimental results of the proposed boost converter using fuzzy control are evaluated in comparison with PD controller. All the analysis and simulations were performed using MATLAB software. The comparison of both the results indicate that the fuzzy controller is able to obtain better dynamic response. The results confirm the capability of the control methods in the improvement of the above-mentioned converter functioning.

A ZVS and ZCS DC-DC converter based on weinberg topology for high voltage applications

Abstract:

This paper proposed a zero voltage and zero current switching (ZVS, ZCS) dc-dc converter based on Weinberg topology. The voltage spike at turn off instant is suppressed by active clamp snubber (ACS), and this circuit is also take part in soft switch operation. With the simple active clamp circuit, high efficiency and power density could be achieved under 800V output voltage. And the conclusion is combined with experimental results for analysis.

DC-DC converter based on the bipolar boost converter and Dickson voltage multiplier

Abstract:

A novel modification of DC-DC converter with a high voltage ratio is proposed. The converter consists of an input boost converter, bridge commutator and Dickson voltage multiplier. The circuit is characterized by a high voltage gain. An important advantage of the circuit is its practically rigid external characteristic in the continuous current mode (CCM). This is achieved by the absence of active power losses in the process of capacitors’ recharging. An additional advantage of the proposed scheme is the low required capacitance of the voltage multiplier capacitors A detailed analysis of the proposed converters has been produced. The results of theoretical analysis are confirmed by the simulation in MATLAB/SIMULINK. Circuit verification has been made in a laboratory prototype with the output power 200W.

Design and development of current source fed full-bridge DC-DC converter for (60V/50A)telecom power supply

Abstract:

This paper addresses a dual input converter (DIC) for telecom power system of 3 kW using digital control algorithm. The proposed system gives an alternative way of fusing the sources of DC in magnetic form, instead of combining in the DC electrical form, by the addition of magnetic flux that is produced in the transformer magnetic core, which works on the principle of flux additivity. A detailed design, operation and control strategy of the proposed dual input isolated full-bridge step down DC-DC converter has been completely evaluated and presented in this paper. A constant frequency phase shifted PWM switching strategy have been preferred for the generation of gate pulses using FPGA controller board. The simulation analysis of the proposed converter has been executed utilizing MATLAB Simulink environment. A prototype for the proposed converter of 1.5 kW has been developed and experimental results are presented to validate the theoretical waveform of the proposed converter.

Bidirectional dual-active-bridge DC-DC converter for vehicle-to-grid applications in DC microgrids

Abstract:

This paper covers the application of a Dual-Active-Bridge (DAB) DC-DC Converter in Vehicle-to-Grid (V2G) technology for DC Microgrids. It comprises of a detailed study of the converter’s behavior in order to achieve soft-switching in the whole operating range independently of the electric vehicle’s battery state-of-charge while also ensuring stability of the Microgrid voltage port regardless of load or generation conditions.

A converter based on energy injection control for AC-AC, AC-DC, DC-DC, DC-AC conversion

Abstract:

Unlike the traditional converter, this paper analyses the feature of the converter based on energy injection control, which can achieve the AC-AC, AC-DC, DC-DC and DC-AC conversion. The detailed operations of the switches in energy injection mode and free oscillation mode are described. Simulations are developed to analyze the feature of the four conversions. The simulation results verify the correctness and effectiveness of the converter.

Hybrid Switched-Capacitor/Switched-Quasi-Z-Source Bidirectional DC-DC Converter with Wide-Voltage-Gain Range for Hybrid Energy Sources EVs

Abstract:

In this paper, a hybrid switched-capacitor/ switched-quasi-Z-source bidirectional dc-dc converter is proposed for electric vehicles (EVs) with hybrid energy sources, which has a wide voltage gain range in the bidirectional energy flows. Compared with the traditional quasi-Z-source bidirectional dc-dc converter, the proposed converter only changes the position of the main power switch, and employs a switched-capacitor cell at the output of the high voltage side. Therefore, the advantages of the wide voltage gain range and the lower voltage stresses across the power switches can be achieved. The operating principle, the voltage and current stresses across the power switches and the comparisons with other converters are analyzed in detail. Furthermore, the parameter design of the main components, the dynamic modelling analysis and the voltage control scheme are also presented. Finally, the experimental results obtained from a 400W prototype validate the characteristics and the theoretical analysis of the proposed converter.

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