Model Predictive Controlled Active NPC Inverter for Voltage Stress Balancing among the Semiconductor Power Switches

© Published under licence by IOP Publishing Ltd. This paper presents a model predictive controlled three-level three-phase active neutral-point-clamped (ANPC) inverter for distributing the voltage stress among the semiconductor power switches as well as balancing the neutral-point voltage. The model predictive control (MPC) concept uses the discrete variables and effectively operates the ANPC inverter by avoiding any linear controller or modulation techniques. A 4.0 kW three-level three-phase ANPC inverter is developed in the MATLAB/Simulink environment to verify the effectiveness of the proposed MPC scheme. The results confirm that the proposed model predictive controlled ANPC inverter equally distributes the voltage across all the semiconductor power switches and provides lowest THD (0.99%) compared with the traditional NPC inverter. Moreover, the neutral-point voltage balancing is accurately maintained by the proposed MPC algorithm. Furthermore, this MPC concept shows the robustness capability against the parameter uncertainties of the system which is also analyzed by MATLAB/Simulink

Active stabilization methods of electric power systems with constant power loads: a review

© 2014, The Author(s). Modern electric power systems have increased the usage of switching power converters. These tightly regulated switching power converters behave as constant power loads (CPLs). They exhibit a negative incremental impedance in small signal analysis. This negative impedance degrades the stability margin of the interaction between CPLs and their feeders, which is known as the negative impedance instability problem. The feeder can be an LC input filter or an upstream switching converter. Active damping methods are preferred for the stabilization of the system. This is due to their higher power efficiency over passive damping methods. Based on different sources of damping effect, this paper summarizes and classifies existing active damping methods into three categories. The paper further analyzes and compares the advantages and disadvantages of each active damping method

SPICE steady state modelling of thermoelectric generators involving the Thomson effect

During operation thermoelectric generators (TEGs) are subject to the following thermal effects; Heat conduction according to Fourier's law, Joule heating, Peltier heating and Thomson heating. Many SPICE-based models exist for TEGs however in the vast majority of them the Thomson effect is neglected due to its relatively small size compared to the other effects, as well as the complexity that results from including the Thomson effect in the model. This paper seeks to present a model that governs the steady state performance of a TEG that includes the Thomson effect whilst limiting the complexity of the SPICE model. © 2011 IEEE

A Simple Internal Resistance Estimation Method Based on Open Circuit Voltage Test under Different Temperature Conditions

© 2018 IEEE. State-of-charge (SoC) is one critical parameter for battery management system. SoC cannot be directly measured but it can be estimated according to some information of battery management system such as voltage and current. Two commonly used methods to estimate the SoC are 1) by using current times a constant internal resistance, and 2) by referring to a SoC-resistance lookup table to interface with an open-circuit-voltage (OCV)-SoC lookup table. However, these widely used testing methods of internal resistance have not considered the influence of SoC, temperature and current rate. which are in fact related to internal resistance. Therefore, ignoring the temperature and current rate factors will obtain inaccurate internal resistance measurement and battery SoC estimation. This paper hence proposes a dynamic resistance model with improved accuracy through combining SoC-OCV at different ambient temperatures with different discharging rates defined at the standard ambient temperature (25 degree) condition. The proposed method will not only improve the accuracy but also reduce the testing time

Non-Isolated Single-Inductor DC/DC Converter with Fully Reconfigurable Structure for Renewable Energy Applications

© 2017 IEEE. A novel non-isolated three-port converter (NITPC) is introduced in this brief. The purpose of this topology is to integrate a regenerative load such as DC bus and motor with dynamic braking, instead of the widely reported consuming load, with a photovoltaic (PV)-battery system. Conventional methods require either a separate DC-DC converter to process the reversible power flow or employing an isolated three-port converter (TPC), which allows bi-directional power flow between any two ports. However, these methods require many switches, which increases the converter size and control complexity. This brief hence presents a compact but fully functional design by combining and integrating basic converters to form a simplified single-inductor converter structure while keeping a minimum amount of switches. The resultant converter is fully reconfigurable that all possible power flow combinations among the sources and load are achieved through different switching patterns, while preserving the single power processing feature of TPC. This brief presents a design example of the proposed NITPC for a PV-battery powered DC microgrid. Detailed circuitry analysis, operation principles of both DC grid-connected and islanded modes, and experimental results of different modes in steady state and mode transitions are presented

Synthesis of dual-input single-output DC/DC converters

© 2019 IEEE This paper presents a topological study using power flow diagrams to derive all possible basic and non-isolated double-input single-output (DISO) converters. Unlike most reported DISO converters with one bidirectional port, this paper considers up to two bidirectional ports. The paper focuses on providing a general guideline of all power flow combinations and corresponding converter configurations. After eliminating the impractical configurations due to their indirect connection to some ports and their multiple conversion stages, three converter configurations have been identified and corresponding circuit realizations are demonstrated

Comparing effectiveness of hybrid mppt algorithms under partial shading conditions

© 2016 IEEE. For photovoltaic (PV) systems, a key area which can affect the amount of energy harvested is the effectiveness of the Maximum Power Point Tracking (MPPT) algorithm, which dynamically locates the operating point for maximum power output. Currently, there are many MPPT algorithms proposed and in use, however, they are not without problems. For example, algorithms such as the Fractional Open Circuit method are simple and effective, but their accuracy is poor. Other algorithms such as the Perturb & Observe (P&O) approach, although more accurate, will cause oscillations around the maximum power point. It is perceived that the use of two MPPT algorithms in tandem will help to overcome the drawbacks of individual MPPT algorithms used in isolation. This paper proposes two new versions of Hybrid MPPT algorithm; one being a combination of the Fractional Open Circuit Voltage and P&O methods, and the other a combination of the Power Increment and P&O techniques. Experimental results are reported to evaluate and compare the performance of the algorithms

A more accurate analog voltage-based photovoltaic maximum power point tracking technique

© 2017 IEEE. In this paper, an analog voltage based maximum power point tracking (MPPT) algorithm for individual photovoltaic (PV) panel is proposed. The fixed voltage reference method is the simplest method for tracking, but it does not give good MPPT efficiency because the MPP voltage point changes at different solar insolation levels. A roughly linear slope is formed when connecting the MPP points measured from the highest isolation level to the lowest. Utilizing this characteristic, a bipolar junction transistor BJT is used to implement a variable voltage reference that improves the accuracy of the maximum power point voltage when the insolation changes. The proposed circuit is simple and easy to implement and it can easily track the maximum power point without the need of a digital controller or PID controller, so the cost and circuit complexity is reduced

Totem-pole bridgeless boost PFC rectifier using series-parallel resonant network

A new series-parallel resonant bridgeless boost (SPBBR) power factor correction (PFC) rectifier is proposed in this paper. It is based on a totem-pole bridgeless boost (TPBLB) configuration which allows bi-directional current to flow during resonance to provide soft-switching for all semiconductor devices. Therefore, no additional active switch is needed. The resonant is produced by a resonant network which is placed before the output capacitor. A detailed analysis of the converter operation and control is presented. Design considerations and parameter values determination are also given. Simulation results is used to verify the theoretical analysis of the SPBBR

A single phase voltage regulator module (VRM) with stepping inductance for fast transient response

A single-phase fast transient converter topology with stepping inductance is proposed. The stepping inductance method is implemented by replacing the conventional inductor in a buck converter by two inductors connecting in series. One has large inductance and the other has small inductance. The inductor with small inductance will take over the output inductor during transient load change and speed up dynamic response. In steady state, the large inductance takes over and keeps a substantially small ripple current and minimizes root mean square loss. It is a low cost method applicable to converters with an output inductor. A hardware prototype of a 1.5-V dc-dc buck converter put under a 100-A transient load change has been experimented upon to demonstrate the merit of this approach. It also serves as a voltage regulator module and powers up a modern PC computer system. © 2007 IEEE.published_or_final_versio