Lyapunov-based high-performance controller for modular resonant DC/DC converters for medium-voltage DC grids

This study presents a high-performance controller based on the Lyapunov stability criterion that enhances the dynamic performance and disturbance rejection capability of resonant DC/DC converters when compared with classical PI control. The series–parallel resonant converter (SPRC) is used as the candidate converter to which this controller design is applied but the design can be generalised to other types of resonant DC/DC converters. By using a multiple module approach, low-power modules of this resonant converter are stacked to enable operation at medium-voltage DC (MVDC). The proposed controller design is applied to modular structure of the SPRC to verify its high-performance output in conjunction with active sharing control loops that ensure uniform current/voltage distribution across the multiple interconnected modules. Detailed controller design, closed-loop stability criteria, robustness and parameter sensitivity are investigated and controller performance is compared and verified against the classical PI control in simulation and low-scaled experimental prototype. Operations in single-module and two-module input-series output-parallel modes are both studied. The study affirms the selection of the modular DC/DC converter architecture and its associated proposed controls for high-performance MVDC applications

Bi-Directional DC-DC Converter

This project was developed with the purpose of creating an efficient energy management system for the DC House project, with a centralized 12V battery system fed by a 48V Multiple Input Single Output Source (MISO). The energy management system will consist of a bidirectional DC-DC converter. During the day when the renewable sources produce enough energy to fulfill the load’s energy demand, the converter will make use of the excess energy by taking a 48V DC input and stepping it down to a 12V DC output in order to charge a 12V 100 Ah battery. When renewable sources can no longer supply the energy required by the load the necessary energy will be pulled from the 12V battery. The converter at this time will take the 12V DC input from the battery and step it up to a 48V output connected to DC House load. The proposed design was tested using LTSpice simulation whose results showed that the converter can indeed provide the bi-directional power flow as desired. Due to COVID-19 pandemic, the originally planned hardware construction must be abandoned following campus shut-down and our inability to get access to lab equipment necessary to conduct the hardware development and testing. Simulation results also showed that the proposed design was able to meet the less than 2% line and load regulation requirements. Furthermore, the efficiency of the proposed converter was measured to be around 85% at full load

Efficiency Optimization of MISO Converter

In recent years, there has been a rapidly growing need for sustainable energy sources. This need comes from the increasing threat of climate change, significant population growth, as well as the effort to bring electricity to rural and underdeveloped areas across the world. The DC House project at Cal Poly aims to address these issues. The Multiple Input Single Output (MISO) converter is an integral part of the DC House project. The MISO converter is a system that connects multiple power sources to a DC bus. This allows the DC House to be powered by multiple types of renewable energy sources, including solar power, wind power, hydro power, and human power. The MISO converter has a nominal input of 24V and a nominal output of 48V with a maximum power rating of 150W. Improvements can be made to the current low-cost MISO to increase efficiency and decrease costs. Several considerations that can be implemented include but are not limited to component selections, board size and layout, and more relaxed design constraints especially for those requirements that were met with significant margin. This project entails the second revision of the low-cost MISO Boost converter incorporating improvements as previously mentioned. Simulation results of the proposed design show that the proposed design meet all design requirements including reduced cost and physical size. Hardware implementation unfortunately did not take place due to the COVID-19 pandemic which caused campus shutdown and thus our inability to access the power electronics lab

Control Strategy to Generate PWM Signals with Stability Analysis for Dual Input Power Converter System

The prime role of a renewable resource based DC hybrid power system is, to maintain the output voltage constant with higher efficiency. In order to achieve this the duty cycles of the converter switches are dynamically controlled. Multiple input single output (MISO) converter uses separate controller for adjusting the duty cycle, this complicates the design and implementation of the system. Hence, to overcome this limitation a centralized controller is used. The control strategy depends on the pattern of gating signals given to the converter switches. When independent controller is employed, then gating signals of any pattern can be used to drive the switches. However, if a single controller is used, and then a definite pattern is very much essential otherwise, the output voltage and efficiency gets affected. In this paper, an attempt is made to validate and evaluate the performance parameters of MISO converter with two pattern of gating signals; they are synchronized and unsynchronized pulses at their rising edge. The control strategy focusses on the generation of these gating pulses. PID controller is tuned appropriately to determine the gains to achieve the stability of the proposed converter.  The dual input power converter validated to show how the PWM pattern affects the efficiency, ripple and regulation of the converter. Using MATLAB SIMULINK platform the simulation of the proposed concept with dual input converter in closed loop is validated. Simulation results proves that synchronized pulses gives DC efficiency of 87% at designed output of 12V output. Converter with unsynchronized PWM pulses operates at lesser efficiency of 75% and the output voltage is of 10V

Design of Novel Fly-Back Converter Using PID Controller

ABSTRACT: Fly-back converters have been widely used because of the irrelative simplicity and their excellent performance for multi output applications. They can save cost and volume compared with the other converters, especially in moderate low power applications..In a fly-back converter, a transformer is adopted to achieve galvanic isolation and energy storage. Modelling is done without parasitic as well as with parasitic components. A detailed analysis, simulation and different control strategy are conferred for Fly-back converter. To verify the design and modelling at primary stage, study of the converter in for input AC voltage220V at 50Hz and output DC voltage of 440V and 150W output power rating. I.INTRODUCTION Fly-back converter is the most commonly used SMPS circuit for low output power applications where the output voltage needs to be isolated from the input main supply. The output power of fly-back type SMPS circuits may vary from few watts to less than 100 watts. The overall circuit topology of this converter is considerably simpler than other SMPS circuits. Input to the circuit is generally unregulated dc voltage obtained by rectifying the utility ac voltage followed by a simple capacitor filter. The circuit can offer single or multiple isolated output voltages and can operate over wide range of input voltage variation. In respect of energy-efficiency, fly-back power supplies are inferior to many other SMPS circuits but it's simple topology and low cost makes it popular in low output power range. The commonly used fly-back converter requires a single controllable switch like, MOSFET and the usual switching frequency is in the range of 100 kHz. A two-switch topology exists that offers better energy efficiency and less voltage stress across the switches but costs more and the circuit complexity also increases slightly. Parameters such as switching frequency, distortion, losses, harmonic generation and speed of response are typical of the issues which must be considered when developing modulation strategies for a particular family of converters .The DC converter is a device which transforms AC to DC i

MULTIPLE INPUT SINGLE OUTPUT CONVERTER WITH UNEVEN LOAD SHARING CONTROL FOR IMPROVED SYSTEM EFFICIENCY

This paper presents the development and study of multiple-input single-output converter (MISO) for the DC House project that utilizes a controller to maximize the overall converter’s efficiency. The premise of this thesis is to create uneven load current sharing between the converters at different loading conditions in order to maximize the efficiency of the overall MISO converter. The goal is to find a proper ratio of current from each converter to the total load current of the MISO system to achieve the greatest efficiency. The Arduino microcontroller is implemented to achieve this goal. The design and operation of the MISO converter with the proposed controller will be explained in this paper. The design and operation of the converter was tested and verified through simulation in LTSpice in addition to hardware implementation. Different ratios of current from each converter were used to fully test the MISO converter. For the 5A and 6A load current, the maximum efficiencies were reached with the 70% / 30% ratio case, with efficiencies of 94.91% and 95.07%, respectively. For 7A load current, the maximum efficiency was reached with the 60% / 40% ratio case, with an efficiency of 94.59%. The results were then compared with those obtained from the equal current sharing cases. For the cases tested, the efficiency of the unequal current sharing outperforms that obtained from the equal current sharing method

Multiport power electronics circuitry for integration of renewable energy sources in low power applications : a thesis presented in partial fulfilment of the requirements for the degree of Doctor of Philosophy in Electrical Engineering at Massey University, Palmerston North, New Zealand

The increasing demand for electricity and the global concern about environment has led energy planners and developers to explore and develop clean energy sources. Under such circumstances, renewable energy sources (RES) have emerged as an alternative source of energy generation. Immense development has been made in renewable energy fields and methods to harvest it. To replace conventional generation system, these renewable energy sources must be sustainable, reliable, stable, and efficient. But these sources have their own distinguished characteristics. Due to sporadic nature of renewable energy sources, the uninterrupted power availability cannot be guaranteed. Handling and integration of such diversified power sources is not a trivial process. It requires high degree of efficiency in power extraction, transformation, and utilization. These objectives can only be achieved with the use of highly efficient, reliable, secure and cost-effective power electronics interface. Power electronics devices have made tremendous developments in the recent past. Numerous single and multi-port converter topologies have been developed for processing and delivering the renewable energy. Various multiport converter topologies have been presented to integrate RES, however some limitations have been identified in these topologies in terms of efficiency, reliability, component count and size. Therefore, further research is required to develop a multiport interface and to address the highlighted issues. In this work, a multi-port power electronics circuitry for integration of multiple renewable energy sources is developed. The proposed circuitry assimilates different renewable sources to power up the load with different voltage levels while maintaining high power transfer efficiency and reliability with a simple and reliable control scheme. This research work presents a new multiport non-isolated DC-DC buck converter. The new topology accommodates two different energy sources at the input to power up a variable load. The power sources can be employed independently and concurrently. The converter also has a bidirectional port which houses a storage device like battery to store the surplus energy under light load conditions and can serve as an input source in case of absence of energy sources. The new presented circuitry is analytically examined to validate its effectiveness for multiport interface. System parameters are defined and the design of different components used, is presented. After successful mathematical interpretation, a simulation platform is developed in MATLAB/Simscape to conduct simulations studies to verify analytical results and to carry out stability analysis. In the final stage, a low power, low voltage prototype model is developed to authenticate the results obtained in simulation studies. The converter is tested under different operating modes and variable source and load conditions. The simulation and experimental results are compiled in terms of converter’s efficiency, reliability, stability. The results are presented to prove the presented topology as a highly reliable, stable and efficient multiport interface, with small size and minimum number of components, for integration of renewable energy sources

Linearized large signal modeling, analysis, and control design of phase-controlled series-parallel resonant converters using state feedback

This paper proposes a linearized large signal state-space model for the fixed-frequency phase-controlled series-parallel resonant converter. The proposed model utilizes state feedback of the output filter inductor current to perform linearization. The model combines multiple-frequency and average state-space modeling techniques to generate an aggregate model with dc state variables that are relatively easier to control and slower than the fast resonant tank dynamics. The main objective of the linearized model is to provide a linear representation of the converter behavior under large signal variation which is suitable for faster simulation and large signal estimation/calculation of the converter state variables. The model also provides insight into converter dynamics as well as a simplified reduced order transfer function for PI closed-loop design. Experimental and simulation results from a detailed switched converter model are compared with the proposed state-space model output to verify its accuracy and robustness

MPPT Control for Solar Splash Photovoltaic Array

This thesis demonstrates the ability to model and simulate the operation of Maximum Power Point Tracking, MPPT. Moreover, the MPPT technology is contextualized within the confines of the Solar Splash competition to provide the foundation for future model development and simulation for optimal competition performance. MatLab Simulink was used to model the solar panel\u27s operation. A MPPT algorithm was written using the perturb and observe method and was implemented in the model using a buck DC to DC converter. The performance of the model with hardware in the loop using Typhoon and dSPACE, which demonstrated how the actual hardware would operate in real time. The results showed that in Simulink, an idealized environment, the MPPT operates as expected. However, hardware simulation revealed inaccuracies of MPPT at lower irradiance values. For all cases, the driving force for changes in power is the value of irradiance