Dual Output Power Management Unit for PV-Battery Hybrid Energy System

The tremendous evolution in the electronics industry has provided high performance portable devices. However, the high power demand and the limited capacity of batteries, prevent the devices from operating for a long time without the need of a power outlet. The ease of deploying Photovoltaic (PV) cells close to the device enables the user to harvest energy on the go, and get rid of the conventional power outlets. However, applying the PV power to the electronic devices is not as easy as the plug and play model, due to the unstable output voltage and power of the PV cells. In this thesis, a power management unit is proposed to provide dual regulated outputs using a PV module and a rechargeable battery. The main components of the unit are a Dual Input Multiple Output (DIMO) DC-DC converter and a digital controller. The converter is used to interface the battery and the PV module with the loads. Moreover, the proposed converter has the ability to step up or step down the input voltage. The controller maximizes the PV power using the fractional open circuit voltage Maximum Power Point Tracking (MPPT) method. Furthermore, the controller manages the amount of power supplied to or from the battery in order to satisfy the load demand and regulate the outputs at the required levels. The controller has been implemented and synthesized using VHDL. A prototype has been implemented using an FPGA and off the shelf components. The functionality of the system has been tested and verified under varying environmental conditions

An Energy Harvesting Solution for IoT Sensors Using MEMS Technology

The significant development of IoT sensors will play a critical role in a large number of applications. It is predicted that billions of IoT sensors will be used worldwide by 2020 [1]. Batteries are commonly utilized to power on sensors, but they are depleted and they require maintenance and replacement. Battery replacement for billions of sensors is a daunting task and battery disposal for IoT sensors can become an environmental problem. Energy harvesting from ambient sources presents a viable solution to overcome these problems. Among all energy sources, light is considered as one of the best sources due to its high energy density and availability in both indoor and outdoor environments. In order to make an energy harvesting system efficient, many methods have been proposed in the literature to extract the maximum energy while minimizing the power consumption by the energy harvesting circuitry. In this work, a boost converter circuit is designed using MEMS-based switches to reduce the leakage current and power loss caused by conventional transistor-based switches. A light energy harvesting method is also proposed utilizing available components of a typical IoT sensor. The reuse of available components in the proposed solution reduces the overall power consumption and the area overhead of the energy harvesting solution

Multi-Input Single-Inductor MPPT Regulator with Sliding-Mode Controller

abstract: A Multi-input single inductor dual-output Boost based architecture for Multi-junction PV energy harvesting source is presented. The system works in Discontinuous Conduction Mode to achieve the independent input regulation for multi-junction PV source. A dual-output path is implemented to regulate the output at 3V as well as store the extra energy at light load condition. The dual-loop based sliding-mode MPPT for multi-junction PV is proposed to speed up the system response time for prompt irradiation change as well as maximize MPPT efficiency. The whole system achieves peak efficiency of 83% and MPPT efficiency of 95%. The whole system is designed, simulated in Cadence and implemented in PCB platform.Dissertation/ThesisMasters Thesis Electrical Engineering 201

Implementation of standalone dynamic solar array fed permanent magnet synchronous motor drive using zero voltage switching resonant converter for the reduction of switching losses and oscillations

The Proposed research deals implementation of standalone dynamic solar array fed permanent magnet synchronous motor drive using zero voltage resonant switch converter for the reduction of switching losses and oscillations. The closed loop control voltage strategy has been proposed for power flow management between solar photovoltaic (PV), battery, motor load and to maintain constant load voltage to perform continuous MPPT operation of solar PV. For improving the efficiency and to reduce vibration across the load SPV array fed Zero Voltage Switching (DISOZVS) Resonant Converter with permanent magnet synchronous motor (PMSM) drive is proposed. The DISOZVS resonant converter with suitable switching operation accomplishes for the purpose of reducing the Switching losses. The ZVS converter is constructed by a buck-boost circuit, which is operated as a buck circuit when charging and a boost circuit when discharging. So, we can use many power related systems, which improves efficiency, lower losses and higher performance. The various dynamics and oscillations of standalone SPV array is analysed in the proposed research. The performance of the proposed system is simulated in MATLAB/Simulink atmosphere and various parameters outputs are carried. A hardware prototype of the proposed system has been fabricated for the proposed converter and various analysis were incorporated. The working of the proposed scheme for the different levels of input solar insolation and Load power demand has been satisfactorily demonstrated for both simulation and experimental compared to conventional it results more efficient with reduced losses and oscillations

Harvesting in electric vehicles: combining multiple power tracking and fuel-cells

Exploitation of green energy sources is essential to diminish the deterioration of our environment. The energy harvesting, represents an alternative to achieve greater range in electric and hybrid vehicles. An energy management strategy (EMS) must be optimized to obtain the best benefits in such vehicles, which is not a trivial task. If harvesting or energy recovery devices are added, the EMS becomes a dual-purpose algorithm: minimizing fuel consumption and maximizing energy harvest through maximum power point tracking (MPPT) controllers. Known studies consider separate EMS, one for traction and another for regenerative braking, without considering harvest devices such as solar panels, regenerative suspension, thermal generators, among others. Furthermore, the electronic power converters used, are not designed to handle such unequal power levels. In this article, an electronic platform to include multiple energy harvesting devices in a fuel-cell hybrid electric vehicle, was presented together with a multiple MPPT-EMS. The EMS is easily implementable, and considers quasiconstant cell energy extraction and filtering of current transients to the battery bank ensuring the longevity of the devices. A new mathematical model of the platform, a closed loop stability analysis, and numerical and Hardware-in-the-Loop (HIL) validations were presented. Some experimental validation results were also provided

An Improved DC-DC Boost Converter for Energy Harvesting

A novel dual-input DC-DC boost converter that can perform the integration of harvested energy from solar and vibrational input energy sources is proposed. Firstly, the background of a hybrid energy system that relates to multi-input DC-DC converters is discussed, and the limitations of the current designs of power converter ICs are highlighted. A detailed design analysis of the proposed converter was done to justify its performance. A current and voltage stress analysis has been performed to ensure suitable switching devices are selected for the converter. Two different power control strategies are proposed for the DIDCB converter to manage output voltage during source and load-side disturbances. Performance analysis of the circuit is carried out using MATLAB Simulink software. Different duty ratios for power switches in the converter were tested to determine the maximum boost ratio and the highest efficiency that can be achieved by the converter. To demonstrate the feasibility of the proposed converter, the performance of the converter is compared with existing converter topologies. The proposed converter achieved a high efficiency of 99.4%, had less fluctuation in the output voltage, and had reduced overshoot. In addition, the proposed converter demonstrated a simpler configuration and required fewer component counts, which helped reduce the cost and size of the system

Design of dual-input two phase dc/dc converter with modified pulse width modulation (mpwm)

Recently, hybrid energy source/renewable energy has attracted interest as the next-generation energy system capable of solving the problems of global warming and energy exhaustion caused by increasing energy consumption. Energy sources such as wind turbines and photovoltaic (PV) systems are intermittent, unpredictable and unregulated. For such systems, the use of multiple-input converter (MIC) has the advantage of regulating and controlling multiple-input sources. With multiple Pulsating Voltage-Source Cells (PVSC) configurations, the proposed converter can deliver power to the load individually and simultaneously. Also, it has the capability of operating either in buck, boost or buck–boost mode of operation. In addition, by proposing the enhanced Modified PWM (MPWM) switching scheme, it is able to solve the issues of the overlapping unregulated input sources. Furthermore, with the proposed multiphase configuration, the input current stresses in the switching devices are reduced and it has the benefit of a reduction in conduction losses. In addition, Zero-Voltage Switching (ZVS) technique is also employed in the proposed converter to reduce the switching loss. The proposed converter circuit is simulated by using MATLAB/Simulink and PSpice software programs. The duty cycle employed to regulate output voltage is reached from Altera DE2-70 board through dSPACE DS1103 board using by Proportional-Integral (PI) controller. The dual-input converter circuit model specification with output power at 200 W, input voltages that range from 10 to 60 V, and operating with dual switching frequencies of 50 kHz and 100 kHz is simulated to validate the designed parameters. Design guidelines, simulation and experimental results are presented. The results show that the proposed two-phase DC/DC converter with ZVS technique achieves 94% efficiency for all ranges of loads compared with the multiphase hard-switching. The total power losses across the power switches are reduced by approximately 37% in the proposed converter. Thus, the proposed converter circuit model offers advantages on input current stress and switching loss reductions. The proposed circuit configuration can be used in a standalone hybrid energy system under unregulated DC input voltages. However the major disadvantages of resonant circuit are increased peak current and voltage stress and not suitable for variable frequency operation

Advanced Control Techniques for Efficiency and Power Density Improvement of a Three-Phase Microinverter

Inverters are widely used in photovoltaic (PV) based power generation systems. Most of these systems have been based on medium to high power string inverters. Microinverters are gaining popularity over their string inverter counterparts in PV based power generation systems due to maximized energy harvesting, high system reliability, modularity, and simple installation. They can be deployed on commercial buildings, residential rooftops, electric poles, etc and have a huge potential market. Emerging trend in power electronics is to increase power density and efficiency while reducing cost. A powerful tool to achieve these objectives is the development of an advanced control system for power electronics. In low power applications such as solar microinverters, increasing the switching frequency can reduce the size of passive components resulting in higher power density. However, switching losses and electromagnetic interference (EMI) may increase as a consequence of higher switching frequency. Soft switching techniques have been proposed to overcome these issues. This dissertation presents several innovative control techniques which are used to increase efficiency and power density while reducing cost. Dynamic dead time optimization and dual zone modulation techniques have been proposed in this dissertation to significantly improve the microinverter efficiency. In dynamic dead time optimization technique, pulse width modulation (PWM) dead times are dynamically adjusted as a function of load current to minimize MOSFET body diode conduction time which reduces power dissipation. This control method also improves total harmonic distortion (THD) of the inverter output current. To further improve the microinverter efficiency, a dual-zone modulation has been proposed which introduces one more soft-switching transition and lower inductor peak current compared to the other boundary conduction mode (BCM) modulation methods. In addition, an advanced DC link voltage control has been proposed to increase the microinverter power density. This concept minimizes the storage capacitance by allowing greater voltage ripple on the DC link. Therefore, the microinverter reliability can be significantly increased by replacing electrolytic capacitors with film capacitors. These control techniques can be readily implemented on any inverter, motor controller, or switching power amplifier. Since there is no circuit modification involved in implementation of these control techniques and can be easily added to existing controller firmware, it will be very attractive to any potential licensees

Modeling And Design Of Multi-port Dc/dc Converters

In this dissertation, a new satellite platform power architecture based on paralleled three-port DC/DC converters is proposed to reduce the total satellite power system mass. Moreover, a fourport DC/DC converter is proposed for renewable energy applications where several renewable sources are employed. Compared to the traditional two-port converter, three-port or four-port converters are classified as multi-port converters. Multi-port converters have less component count and less conversion stage than the traditional power processing solution which adopts several independent two-port converters. Due to their advantages multi-port converters recently have attracted much attention in academia, resulting in many topologies for various applications. But all proposed topologies have at least one of the following disadvantages: 1) no bidirectional port; 2) lack of proper isolation; 3) too many active and passive components; 4) no softswitching. In addition, most existing research focuses on the topology investigation, but lacks study on the multi-port converter’s control aspects, which are actually very challenging since it is a multi-input multi-output control system and has so many cross-coupled control loops. A three-port converter is proposed and used for space applications. The topology features bidirectional capability, low component count and soft-switching for all active switches, and has one output port to meet certain isolating requirements. For the system level control strategy, the multi-functional central controller has to achieve maximal power harvesting for the solar panel, the battery charge control for the battery, and output voltage regulation for the dc bus. In order to design these various controllers, a good dynamic model of the control object should be obtained first. Therefore, a modeling procedure based on a traditional state-space averaging method is v proposed to characterize the dynamic behavior of such a multi-port converter. The proposed modeling method is clear and easy to follow, and can be extended for other multi-port converters. In order to boost the power level of the multi-port converter system and allow redundancy, the three-port converters are paralleled together. The current sharing control for the multi-port converters has rarely been reported. A so called “dual loop” current sharing control structure is identified to be suitable for the paralleled multi-port converters, since its current loop and the voltage loop can be considered and designed independently, which simplifies the multi-port converter’s loop analysis. The design criteria for that dual loop structure are also studied to achieve good current sharing dynamics while guaranteeing the system stability. The renewable energy applications are continuously demanding the low cost solution, so that the renewable energy might have a more competitive dollar per kilowatt figure than the traditional fossil fuel power generation. For this reason, the multi-port converter is a good candidate for such applications due to the low component count and low cost. Especially when several renewable sources are combined to increase the power delivering certainty, the multi-port solution is more beneficial since it can replace more separate converters. A four-port converter is proposed to interface two different renewable sources, such as the wind turbine and the solar panel, one bidirectional battery device, and the galvanically isolated load. The four-port converter is based on the traditional half-bridge topology making it easy for the practicing power electronics engineer to follow the circuit design. Moreover, this topology can be extended into n input ports which allow more input renewable sources. vi Finally, the work is summarized and concluded, and references are listed

Efficiency Optimization in Burst-Mode Buck DC/DC Converters for Sensor Nodes

© 2017 IEEE. Personal use of this material is permitted. Permission from IEEE must be obtained for all other uses, in any current or future media, including reprinting/republishing this material for advertising or promotional purposes,creating new collective works, for resale or redistribution to servers or lists, or reuse of any copyrighted component of this work in other works.In autonomous sensor nodes, switching dc/dc converters are usually employed to power the sensor electronics and also to maintain the operating voltage of an energy transducer around its maximum power point. In such a context, this paper optimizes the power efficiency of buck dc/dc converters when operating in burst mode, which is preferable than the conventional pulse-width modulation technique in lowpower sensor applications. The optimization is carried out by selecting an optimal inductor current to efficiently transfer the energy from the input to the output during the burst. Such optimization is applied when regulating the converter’s output voltage, which corresponds to the supply voltage of the sensor electronics, and also the input voltage, which corresponds to the operating voltage of the energy transducer that is here a photovoltaic module. The theoretical analysis and the experimental results reported herein prove the existence of such an optimal inductor current in both scenarios. Experimental tests with a commercial buck dc/dc converter (TPS62750) show that the use of this optimal inductor current provides up to 9% increase in efficiency, thus prolonging the operating lifetime of the sensor node.Peer ReviewedPostprint (published version