Interconnection and damping assignment passivity-based controller for multilevel inverter

This thesis proposes an Interconnection and Damping Assignment Passivity- Based Controller (IDA-PBC) to control a 5-level Cascaded H-Bridge Multilevel Inverter (CHMI). The proposed IDA-PBC uses the Port-Controlled Hamiltonian (PCH) theory to modify the CHMI system energy by adding damping, thereby modifying dissipation structures related to dynamics and stability. The objective is to maintain output voltage regulation, resulting in fast response and low Total Harmonic Distortion (THD) values. Although the proposed IDA-PBC control algorithm showed outstanding performance during transient and nonlinear load condition, further improvements are required during no-load condition. To address this, improvements in the form of modification to the proposed IDA-PBC algorithm was made by adding a single loop Proportional-Integral (PI) controller at the voltage side, which was aimed at regulating the voltage before it was fed back into the IDAPBC. In order to verify the viability of the proposed IDA-PBC-PI controller for the CHMI, a simulation study was conducted using MATLAB/Simulink at a 20 kHz switching frequency and 1 µs sample time. The controller was tested at five load conditions, namely, steady state, no-load to full-load, load uncertainty, structural uncertainty and nonlinear load condition. The performance of the proposed controller showed regulated output voltage while maintaining THD values below 5% in all load conditions and a maximum of 220 µs response time during load uncertainty. The simulation results revealed the superiority of the proposed controller compared to the conventional double loop PI controller and the conventional IDA-PBC in terms of transient response, THD value, as well as regulation of the output voltage. The feasibility of the proposed IDA-PBC-PI controller was validated by developing its proof-of-concept hardware prototype. The simulation and experimental results obtained based on a 3 kHz switching frequency and 38 µs sample time were found to be consistent, which confirmed the capability of the proposed controller in controlling the 5-level CHMI output voltage

Visualization of Academic Quality Assurance Metamodel Through the Creation of Academic Quality Assurance Metamodel Information System

Academic quality assurance metamodel information system (AQAMIS) is a mobile-web-friendly system designed to manage academic quality assurance (AQA) knowledge structure for higher education using the AQA metamodel structure. This research describes the development and functionality of AQAMIS, as well as how it visualizes the AQA metamodel on a system-based level. The AQAMIS system transformed the metamodel class diagram design into a user-friendly design, making it easier for any non-technical user to understand the metamodel design. The AQAMIS is composed of two major parts: the AQA metamodel and the knowledge repository system. The metamodel addresses the issue of managing knowledge for quality assurance in higher education. While the system resolves the issue of sharing best practices in higher education AQA. The AQAMIS system assists in ensuring that academic quality assurance systems are implemented more efficiently and effectively in higher learning institutions (HLIs). AQAMIS is also a one-stop center for respective users such as HLI top management, policymakers, auditors, and quality assurance personnel to access their expertise and share best practices in AQA endeavors

Investigation of power transfer in QAB converter via phase shift modulation

In line with high demand of renewable energy as well as the energy storage, the multiport DC-DC converters topology have recently received a lot of attention due to its own advantages. In this paper, a bidirectional quad active bridge (QAB) DC-DC converter with high frequency transformer is presented. Full bridge power converter is employed and the phase shift modulation is used in investigating the power transfer of QAB converter. In applying this proposed modulation, the changing or amount of delivering and receiving power in the QAB converter are influenced by the phase shift. Multiple cases of QAB config-uration have been evaluated by 1) Multi-input single-output (balanced voltage source); 2) Multi-input single output (unbalanced voltage source); 3) Multi-input multi-output (balanced voltage source); and 4) Single-input multi-output (unbal-anced load). The simulation results of a 2.5 kW system is analyzed through MATLAB/Simulink. Also, the power efficiency is discussed through this simu-lation. It is found out that maximum power can be achieved at 90° phase shift

PSO tuning pi controller for multilevel inverter output voltage regulation

In recent decades, renewable energy production has been an underlying trend in the energy sector. Multilevel inverter has been used especially in renewable energy aspects in order to assess Total Harmonics Distortion (THD). Multilevel inverters have shown superior performance in terms of reducing harmonic disturbances, torque pulsations, and voltage stress through switching devices. Conventionally, PI controller are preferable to be applied in multilevel inverter due to its simplicity. However, it has a limitation of optimization when it comes to increase of loads under working condition. This paper focuses on developing a Particle Swarm Optimization (PSO) algorithm for optimal tuning of PI controller for Cascaded H-Bridge Multilevel Inverter (CHMI) in order to regulate a smooth output voltage of the system. PSO controller is implemented to produce an optimum regulated output voltage using MATLAB/Simulink. The system will go under three load variation conditions. The PSO-PI controller have been applied to a 7-level CHMI that uses 12 IGBTs with 20kHz switching frequency and 0.9 modulation index with 0.4 μs of sample time. As compared PSO-PI to conventional PI controller during nominal load, 20 % reduction in THD is observed. In addition, voltage drop and transient time during no load to full load shows an improvement after applying PSO-PI. During load variation was halved and varied at certain point, PSO-PI also exhibit improvement in transient time and reduction in THD is observed compared to conventional PI controller

Time-variant online auto-tuned pi controller using pso algorithm for high accuracy dual active bridge dc-dc converter

The proliferation of clean energy and environmentally friendly transportation has contributed to the development of electric vehicles (EVs) including the EV DC charger system. A dual active bridge (DAB) is a DC-DC converter that has the required features for an EV DC charger. A proportional-integral (PI) controller is a common method in power electronics applications, including DAB. However, the manual tuning of PI parameters using Ziegler-Nichols (ZN) needs a lengthy time and the tuning values are practical and well-functioning at the tuning point only. Moreover, the fixed gains in offline tuning cannot fully control the system output as needed and do not guarantee the robustness of the system. This paper proposes a time-variant online auto-tuned PI controller using a particle swarm optimization (PSO) algorithm for the 200 kW DAB system. The DAB performance with the proposed controller is evaluated in terms of steady-state error, eSS and dynamic performance under various reference voltages at different loads and load step changes. Comparative analysis between the proposed method and manual tuning performance are presented. A hardware-in-the-loop (HIL) experimental circuit is built to validate the simulation results. The DAB with the proposed method produces 64% higher accuracy and 40% faster response compared to manual tuning. tuning

A high accuracy control of dual active bridge DC-DC converter using PSO online direct tuning

The dual active bridge (DAB) is amongst the popular DC-DC converter in literature due to its attractive feature such as bidirectional power flow, galvanic isolation and high power density. The conventional proportional-integral (PI) controller is a controller that has been widely used in power electronics field including DAB converter due to its reliability. However, it has less performance especially at the condition that far from the point of tuning. This paper proposes an online tuning of phase-shift angle using particle swarm optimization (PSO) algorithm for the 200 kW 20 kHz DAB system. The system is controlled directly by PSO without the existence of PI controller. Simulation has been carried out with the objective to minimize the steady-state error, eSS of the DAB. The DAB performance with the proposed solution is evaluated in terms of eSS by testing the system under various reference voltages at different loads. Comparative analysis between the proposed method and the PI using Ziegler-Nichols (ZN-PI) method performance are presented. In order to validate the simulation results, a hardware-in-the-loop (HIL) experimental circuit is built in Typhoon HIL-402 to verify the steady state performance of the system. The DAB system with proposed method produces higher accuracy by producing smaller eSS as compared to the DAB system with ZN-PI method

Adaptive online auto-tuning using Particle Swarm optimized PI controller with time-variant approach for high accuracy and speed in Dual Active Bridge converter

Electric vehicles (EVs) are an emerging technology that contribute to reducing air pollution. This paper presents the development of a 200 kW DC charger for the vehicle-to-grid (V2G) application. The bidirectional dual active bridge (DAB) converter was the preferred fit for a high-power DC-DC conversion due its attractive features such as high power density and bidirectional power flow. A particle swarm optimization (PSO) algorithm was used to online auto-tune the optimal proportional gain (KP) and integral gain (KI) value with minimized error voltage. Then, knowing that the controller with fixed gains have limitation in its response during dynamic change, the PSO was improved to allow re-tuning and update the new KP and KI upon step changes or disturbances through a time-variant approach. The proposed controller, online auto-tuned PI using PSO with re-tuning (OPSO-PI-RT) and one-time (OPSO-PI-OT) execution were compared under desired output voltage step changes and load step changes in terms of steady-state error and dynamic performance. The OPSO-PI-RT method was a superior controller with 98.16% accuracy and faster controller with 85.28 s-1 average speed compared to OPSO-PI-OT using controller hardware-in-the-loop (CHIL) approach

Detection of back-side cracks in steel structure using a differential Eddy

Eddy current testing (ECT) is a technique that is used to identify deficiencies and faulty in metallic components including aircraft, piping, bridges, and other civil engineering structures. Early detection of cracks is essential for ensuring structural integrity, safety, and reliability before it reaches the point of fracture. ECT method becomes common in NDT because it can detect a defect in conductive materials. Crack can exist in any form of size and shape either on surface or subsurface components where it can contribute to the complete fracture. The development of an ECT probe for the evaluation of backside defects in the galvanized steel plate is discussed in this paper. The ECT probe is developed based on fluxgate sensors for identifications of defects. The ECT probe that was created is assessed by executing a phase-sensitive detection technique at the excitation field of 70 Hz to 310 Hz. The efficiency of the magnetic probe is estimated by identifying the existence of slits based on the changes of the magnetic response where the induced eddy current is caused. Using the developed magnetic probe, the signal intensity is evaluated on the backside of the sample plate. The results show a signal change in the crack area. The integrated ECT probe is expected to be applied for the evaluation of backside inaccuracies

Detection of back-side cracks in steel structure using a differential eddy current testing probe

Eddy current testing (ECT) is a technique that is used to identify deficiencies and faulty in metallic components including aircraft, piping, bridges, and other civil engineering structures. Early detection of cracks is essential for ensuring structural integrity, safety, and reliability before it reaches the point of fracture. ECT method becomes common in NDT because it can detect a defect in conductive materials. Crack can exist in any form of size and shape either on surface or subsurface components where it can contribute to the complete fracture. The development of an ECT probe for the evaluation of backside defects in the galvanized steel plate is discussed in this paper. The ECT probe is developed based on fluxgate sensors for identifications of defects. The ECT probe that was created is assessed by executing a phase-sensitive detection technique at the excitation field of 70 Hz to 310 Hz. The efficiency of the magnetic probe is estimated by identifying the existence of slits based on the changes of the magnetic response where the induced eddy current is caused. Using the developed magnetic probe, the signal intensity is evaluated on the backside of the sample plate. The results show a signal change in the crack area. The integrated ECT probe is expected to be applied for the evaluation of backside inaccuracies