Output Voltage Control Research Articles

A new frequency control method to enhance fault ride-through capability of VSC-HVDC systems supplying industrial plants

• Voltage sags is the most important issue of power quality, which can disrupt industrial process and impose huge costs on industrial plants. • A new frequency control method is proposed for the VSC-HVDC in order to improve the voltage stability in industrial plants during voltage sag. • The performance of the proposed method is investigated under 3LGF, DLGF, and SLGF conditions. • The proposed method maintains the minimum AC voltage at an acceptable value for very sensitive loads, when voltage drop occurs under severe faults. Voltage sags is one of the most important issue of power quality, which can disrupt industrial process and impose huge costs on industrial plants. For improving disturbance ride-through capability of voltage source converter based on high voltage direct current (VSC-HVDC) supplying industrial plant, an auxiliary frequency controller is proposed to control output voltage frequency at inverter station. Since industrial loads are more sensitive to voltage drops compared to frequency deviations, output voltage frequency is slightly deceased based on DC-link voltage changes during disturbances in proposed control scheme in order to prevent voltage collapse and provide desirable voltage quality for industrial plants; hence, the continuity of industrial process will be ensured. The case study is a part of a real industrial plant and variations of DC-link voltage, AC buses voltages, induction motors speed, and performance of adjustable speed drive are investigated when the proposed method is used during faults. In proposed method, voltage drop across industrial plant during a severe fault is less than other methods and dynamic performance of system is improved. The case study is simulated under balanced three-phase fault, double line-to-ground fault, and single line-to-ground fault in PSCAD/EMTDC, and results verify the validity of the proposed control scheme.

Development of control algorithms for magnetoelectric generator with axial magnetic flux and double stator based on mathematical modeling

The object of this research is electromechanical processes in a generator with an axial magnetic flux and a double stator and an additional non-contact excitation winding operating as part of autonomous electric power systems. The power of the additional excitation system is about 2 % of the generator power. The presence of an additional non-contact winding, which is powered by direct current, makes it possible to control the generator voltage by changing the excitation current. This resolves the task to stabilize the output voltage of the generator with permanent magnets when the load and shaft speed change. This paper reports the construction of a three-dimensional field axisymmetric mathematical model of the generator under study, which has made it possible to calculate and investigate its characteristics and parameters, in particular the magnitude of magnetic induction in all structural elements. The model built takes into account the influence of finite effects, magnetic scattering fields, and the radial-axial nature of the closure of the main magnetic flux and the magnetic flux of the additional excitation winding. The use of a structure with a double stator makes it possible to more efficiently utilize the usable volume of the generator and to increase its power. A mathematical model of the generator in the d-q coordinate system was built, which has made it possible to synthesize algorithms for controlling the automatic voltage stabilization system of the generator voltage under conditions of change in load and shaft speed. Control algorithms were developed on the basis of the concept of inverse dynamics problems in combination with minimizing local functionalities of instantaneous energy values, which ensures that the system is robust when changing generator parameters and that regulators are implemented in a simple way, due to the lack of differentiation operations. Based on the models built and algorithms developed, the quality of control of the generator's output voltage when the load and frequency of the generator change was investigated by modeling in the MATLAB/Simulink environment. When setting a jump in the rated load and changing the rotational speed within ±15 % of the rated value, the automatic stabilization system provides astatic voltage control at a given level of 48 V. The results can be practically used in the design of autonomous electric power systems with high energy conversion efficiency, in particular wind turbines and hydraulic units

Comparison of Interleaved Boost Converter and Two-Phase Boost Converter Characteristics for Three-Level Inverters

A boost converter is used in various applications to obtain a higher voltage than the input voltage. One of the current main circuit systems for hybrid electric vehicles (HEVs) is a combination of a two-phase boost converter (parallel circuit) and a three-phase two-level inverter. In this study, we focus on the boost converter to achieve even higher efficiency and propose an interleaving scheme for a boost converter suitable for a three-level inverter (series circuit). The series circuit has two capacitors connected in series and makes it suitable as a power supply for a three-level inverter. We analyze the input current ripple of the series and parallel circuit in order to show the superiority of the series circuit. Furthermore, we propose a novel output voltage control strategy using an optimal regulator, namely a Linear Quadratic Regulator (LQR), for the series circuit. As a result, we found the input current ripple of the series circuit is smaller than the parallel circuit and demonstrated the superiority of the series circuit. The simulation and experimental results show the effectiveness of the proposed interleaving scheme and optimal regulator.

A Novel Control Scheme Based on Exact Feedback Linearization Achieving Robust Constant Voltage for Boost Converter

This paper presents a novel form of feedback linearization control (FBL) of boost-type DC/DC converter: to reach highly accurate output voltage control. Integral action has been inserted into the block diagram of the control scheme. The state-space model of the boost converter is highly nonlinear. Accordingly, the design procedure of the controller is more complex. The paper presents the state-space modeling of the boost converter and details the design procedure of the nonlinear FBL controller step by step. The main goal of this paper is to highlight the importance of the error integrator in the FBL control loop. The proposed method has been tested by a numerical example and compared with an existing and validated two-loop controller. Both the dynamical and steady-state behavior of the examined boost converter performed better than the reference system. The steady-state error of the output voltage is almost eliminated, while the dynamical error decreased to 5% in comparison to the two-loop controller.

Design of intelligence‐based optimized adaptive fuzzy PID controllers for a two chamber microbial fuel cell

AbstractThe output voltage of microbial fuel cells (MFCs) needs to be controlled effectively to improve the operating efficiency of MFC system against the load variations, disturbances, and uncertainties. The output voltage control is purposed to provide the MFC with an appropriate amount of fuel required to maintain the stability of output voltage. In the applications, the MFC output voltage can be requested to track the variable reference voltage or to track the constant output voltage under changing conditions such as load change. For this purpose, two adaptive fuzzy PID (FPID) controllers powered by optimization algorithms were designed in this study to keep the output voltage value of the MFC at the desired values. This study extends the previous works by using optimization algorithms, such as particle swarm optimization (PSO) and gray wolf optimization (GWO) algorithms, to adjust fuzzy logic parameters, which are used for tuning Proportional‐Integral‐Derivative (PID) controllers. The optimization‐based adaptive FPID controllers play an active role in efficient, fast, and robust tracking of the reference voltage value with its adaptive structure. The designed adaptive control algorithms were tested under different cases, which involve the variation of the reference voltage and load conditions. The results show that both of these controllers can effectively control the output voltage of a MFC by regulating the flow rate of the fuel. In addition, the performances of the designed controller strategies according to the results obtained vary according to the reference signal. While PSO‐based FPID gives more successful results for positive step changes, GWO‐based FPID gives more successful results for negative step changes. These two control strategies show more efficient, robust, successful, and faster performances compared to the traditional PID controller.

Quantitative Design for the Battery Equalizing Charge/Discharge Controller of the Photovoltaic Energy Storage System

The purpose of this paper is to develop a photovoltaic module array with an energy storage system that has equalizing charge/discharge controls for regulating the power supply to the grid. Firstly, the boost converter is used in conjunction with maximum power point tracking (MPPT) such that the photovoltaic module array (PVMA) can output maximum power at any time. The battery equalizing charge/discharge architecture is composed of multiple sets of bidirectional buck–boost soft-switching converters in serial connection in order to achieve zero-voltage switching (ZVS) and zero-current switching (ZCS) so that when the charge/discharge power is above 150 W, the converter efficiency can be increased by 3%. The voltage and current signals from the battery are captured and input into the digital signal processor (DSP) to establish an equalizing charge/discharge control rule. For the output voltage control of the bidirectional buck–boost soft-switching converter, the dynamic mode is derived by first using the step response at chosen operating point, then quantitatively designing the controller parameters for the converter, so that the output voltage response can meet the pre-defined performance specifications. Finally, actual test results prove that the equalizing charge/discharge time of the quantitative design controller is shortened by more than 10% when compared to the traditional proportional-integral (P-I) controller regardless of charging or discharging; this also proves that the design of the photovoltaic module array with an energy storage system (ESS) that has equalizing charge/discharge controls is valid.

Analysis and Fault-Tolerant Control for Dual-Three-Phase PMSM Based on Virtual Healthy Model

Dual-three-phase permanent magnet synchronous machines (DTP-PMSMs) are famous for their fault-tolerant capability. However, the complex modeling, high copper loss, and torque ripple under postfault operation limit their further application. In this article, a fault-tolerant control (FTC) strategy is developed for DTP-PMSMs under the open-phase fault (OPF) with straightforward modeling and smooth output torque. The virtual healthy DTP-PMSM model, where the coordinate transformation, the modulation strategy, and the controller structure remain unchanged under OPF, is adopted in the proposed FTC scheme. And the current references are derived in sinusoidal waves with minimum copper loss. The inaccurate transmission of control signals under OPF is also focused on. Comprehensive theoretical analysis shows the relationship between the controller output voltage and the actual stator voltage should be considered in the proposed FTC strategy; otherwise, distortion in torque and current will be introduced. The voltage compensation is utilized to compensate for the voltage difference and ensure the smooth torque output. Besides, a quasi proportional resonance controller is designed to further suppress the residual torque ripple. The proposed strategy will not induce complex implementation and heavy computation burden. The simulation and experimental results prove the analysis and the effectiveness of the proposed strategy.

A novel SVPWM for 3-phase to 5-phase conversion using matrix converter

<span>A novel matrix converter has been developed for 3-phase to 5-phase conversion using a novel space vector pulse width modulation. The matrix converter organized to generate 5-phase AC output voltage from 3-phase input voltage with help of SVPWM method; bidirectional power switches placed in matrix converter controlled by appropriate switching pulse. Space vector pulse width modulation (SVPWM) provides better utilization of applied input voltage, improved output voltage, reduced total harmonic distortion. The bidirectional switch used by the matrix converter decreases stress on the power switch and the influence of harmonic fluctuation in AC output voltage. When compared to traditional approaches, the suggested system offers improved output voltage and current control. Using MATLAB/Simulink and FPGA-cyclone controller, respectively, modelling and experimental results have been given to validate the proposed methodology.</span>

Modeling Analysis of Superbuck Converter in Dual-Loop Competition Control

A Battery Charge Regulator system based on the Superbuck converter is presented, the working principle of the Superbuck converter is analyzed and the small signal model is established. In order to meet the requirements of wide input range and high dynamic response of the Superbuck converter, a double closed-loop control system is designed with output voltage and output current dual loop control as outer loop and input current control as inner loop. The stability of the control loop is verified by the Bode plot, and the simulation result of the system in two working conditions are given to support the theoretical analysis.

Single Phase T-Type Multilevel Inverters for Renewable Energy Systems, Topology, Modulation, and Control Techniques: A Review

Multilevel inverters (MLI) consist of a wide range of power converters. They have many designs and have been introduced with different circuit topologies such as neutral point clamped, diode clamped, cascaded H-bridges, and flying capacitors. Some of these MLIs have disadvantages, including design complexity, size, and losses due to the large number of switching devices required when they produce many output voltage levels. They are also bulky in size and may require several DC power sources. This paper presents a review of the various topologies of single-phase T-Type MLIs (T-MLIs). These MLIs are used to convert DC power from renewable energy sources (RES)” into AC with a near-sine waveform and low total harmonic distortion (THD). Simple and complex MLI designs are discussed. The major types of modulation techniques are discussed, including sinusoidal pulse width modulation (SPWM), selective harmonic elimination (SHE), and preprogrammed PWM. Various methods of output voltage control are taken into consideration as well. The aim of this comprehensive survey is to identify T-MLIs for researchers and those interested in the power conversion field, as well as to discuss the many topologies, identifying designs with superior characteristics that can be efficiently implemented with RESs to obtain better AC voltage with enhanced power quality.

Cascaded Controller for Controlling DC Bus Voltage in Mismatched Input Powers

The lack of uniform production of panels in photovoltaic (PV) systems and snowball effects in fuel cell (FC) systems led us to use a separate dc–dc converter. In addition, in the PV and FC systems, the output voltage is low. Hence, dc–dc boost converters are commonly used in a series connection. Each small unit of a PV or FC operates independently. Therefore, another problem arises in the system that uses the series connection of the converter's output. Owing to the unequal electricity production of the cells, a voltage imbalance occurs at the output terminals. To create voltage balance, a modular structure grounded on a three-level boost converter was investigated. The main objective of this article is to design the control of a modular topology, allowing perfect control of the dc-bus voltage, even with mismatched input powers. The proposed control strategy ensures dynamical properties independent of the operating point, voltage balance, and robust control of the dc output voltage with respect to load perturbations. To ensure the balance of voltages and the control of currents, a sliding mode controller based on indirect synthesis was used. To control the dc–bus voltage, an energy controller is proposed that ensures dynamical performance independent of the operating conditions. The performance in terms of tracking and regulation, as well as its effect on the voltage balance of the output capacitors, was validated through simulations and experimental results. A comparison with a classical proportional integral (PI) approach for controlling the dc-bus voltage was performed.

Buck DC-DC 컨버터와 적응 퍼지 제어 시스템을 이용한 태양광 발전 어레이 출력 전압 제어

In solar PV generation, energy conversion efficiency is a very important problem. Hence several important MPPT(Maximum Power Point Tracking) schemes have been proposed and the PV array output voltage is required to track the desired reference voltage determined from the P&O(Perturb and Observation) algorithm of the MPPT cotrol scheme. PV array output voltage dynamic equations are very uncertain and nonlinear under variant atmospheric conditions such as solar radiation and ambient temperature. So the conventional simple control algorithm may not be appropriate to get the good transient performance of the PV array output voltage control. To cope with this problem, an adaptive fuzzy control system for the duty rate control of the Buck DC-DC converter is proposed in this paper and its usefulness is proved by some simulation studies.

A Simple Closed-Loop Test Based Control of Boost Converter Using Internal Model Control and Direct Synthesis Approach

In this article, a simple controller design method for output voltage control of dc–dc boost converter (BC) has been proposed. A simple closed-loop step test with proportional gain <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$k_{0}$ </tex-math></inline-formula> is performed. BC open-loop transfer function is obtained from the closed-loop step response test data, which does not require information of BC circuit parameters. Furthermore, the controller is designed from the open-loop model of the BC through the internal model control (IMC) scheme and direct synthesis (DS) approach. The robust stability analysis of both the control schemes has been carried out. The proposed modeling technique and controller design methods have been validated in the experimental setup. Both the controller design techniques work satisfactorily. Superior transient performance of the IMC scheme in comparison to the DS scheme has been observed.

Performance analysis of capacitor voltage balancing in modular multilevel converter by sorting algorithm

&lt;span lang="EN-US"&gt;Due to the modularity of modular multilevel converter (MMC), therefore it has been considered as a substitute for the diode-clamp multilevel inverter in applications of high-voltage high-power. Where it can obtain any level of voltage without imposing complexity on the control system. This study analyses in detail the operation principle and balances the capacitor voltage of sub-module (SM) in modular multilevel converter by sorting algorithm. The output voltage control and capacitor voltage balancing technique are confirmed by MATLAB/Simulink and the obtained result has been discussed, where the capacitor voltage of the sub-module has controlled within the acceptable deviation limit, which is 5-10%. In addition, the circulating current has been controlled and reduced.&lt;/span&gt;

Optimization design and analysis of permanent magnet synchronous generator based on Motor-CAD

With the development of the automotive industry, the demand for electricity for automotive equipment increases, which puts forward higher requirements for automotive generators. Compared with the traditional electric excitation generator, the permanent magnet synchronous generator (PMSG) has the characteristics of high efficiency, high power density, stable and controllable output voltage, and good heat dissipation performance, and is especially suitable for automotive applications. According to its characteristics, this paper makes an in-depth study on its design theory and main performance parameters. A high-efficiency rotor magnetic steel built-in vehicle permanent magnet synchronous generator is designed by using motor CAD, which eliminates the easily damaged collector ring and brush, improves the reliability of the motor, opens a ventilation hole in the rotor, enhances the heat dissipation effect, and adopts a skewed stator to effectively reduce the sinusoidal distortion rate of the output voltage waveform. The prototype has the characteristics of high power, small size and high reliability. The various performances of the prototype are analysed and verified on the simulation software. The results show that the performance of the prototype meets the design requirements, and the simulation results prove the rationality of the prototype design.

An Active Clamp Flyback Converter With High Precision Primary-Side Regulation Strategy

The active clamp flyback (ACF) converter has been widely adopted because of the feature of isolation, soft-switching, and high conversion efficiency. On the other hand, due to the characteristic of the circuit cost reduction and the fast control response, the primary-side regulation (PSR) has become a popular control method for isolated power converters. However, high precision PSR strategies for ACF converters are not exposed. Therefore, the aim of this article is to propose a high precision PSR strategy for the ACF converter. Relations between the primary-side current and the secondary-side current are analyzed and derived. Both of the continuous conduction mode operation and the discontinuous conduction mode operation will be considered. The output voltage control mode or the output current control mode can be selected via the proposed strategy. In addition, a secondary-side losses compensation (SSLC) strategy is developed to deal with the non-ideal circuit characteristics as well as to enhance the control accuracy. Operational principles and thorough mathematical derivations will also be revealed. Finally, both simulation and experimental results obtained from a 100 W prototype circuit demonstrate the performance and feasibility of the proposed PSR and SSLC strategy. Validations show that the control accuracy of the output voltage and the output current are 98.54% and 98.42%, respectively.

Analysis, Design, and Experimental Verification of a Parallel Wireless Power and Data Transmission Method for Rotary Steering Systems

In the rotary steering system of oil drilling, both power and data transmission are needed. This paper presents a parallel power and data transmission method for a rotating steering system with output voltage control. To reduce the size of the system, power and data are transmitted through the same rotational coupling mechanism. A power transfer resonance circuit is used to suppress the influence of the power transfer on data transmission. Therefore, crosstalk interference between the power and the data transmission channel is negligible. The experimental prototype is built, and the feasibility of the data transfer method and the closed-loop control method is verified. The experimental results are in good agreement with the theoretical analysis.

Active control of combustion oscillation with active disturbance rejection control (ADRC) method

This research aims to develop a novel method for the active control of combustion oscillation based on active disturbance rejection control (ADRC). The effectiveness of parameter tuning and the controller in suppressing combustion oscillation was studied by simulation and experiments. The control performance was verified using a Rijke tube and turbulent premixed swirling flame within a model combustor. For the former, the results show that the first-order ADRC can rapidly mitigate the limit cycle oscillation and maintain the effectiveness of the control when the oscillation frequency changes. For the latter, a system identification method based on an acoustic network was adopted. Combining the identification results with a thermoacoustic network, the formation process of the limit cycle oscillation and the effectiveness of the first-order ADRC were simulated by SIMULINK. The experimental results show that the first-order ADRC performs better than the proportional–integral–derivative (PID) controller. At the same time, the first-order ADRC and second-order ADRC achieve good outcomes when the equivalence ratio changes. However, the second-order ADRC exhibits a better pressure-suppression effect and smaller controller output voltage.

Modelling and output voltage distortion with capacitive current feedback control for single phase inverter powering non‐linear load

The pulse width modulation inverter is widely applied in independent PV renewable generation applications and uninterruptible power supplies. Many control schemes are investigated for the inverter feeding non-linear loads, aiming to achieve the desired performance. However, the model currently proposed is mostly based on a linear load, which is not suitable for the condition with the non-linear load. In this paper, the uncontrolled diode rectifier load model based on the AC and DC link power balances is analysed in detail first. Then, the rectifier inverter control system mathematical model is presented. The mathematical model derivation considers the rectifier load, especially non-linear dead zone circuit performance that is closer to practical application conditions. Based on the proposed model, the output voltage control strategy with capacitor current feedback is further given. The operating principle of the proposed model and control scheme is analysed in detail. Additionally, the conclusions are validated by simulations and experimental results.

Optimal trajectory exploration large-scale deep reinforcement learning tuned optimal controller for proton exchange membrane fuel cell

To accurately regulate hydrogen flow and guarantee satisfactory output voltage control performance, taking advantage of the high adaptability and robustness of large-scale deep reinforcement learning, an optimal fractional-order proportion integral differential (FOPID) controller for controlling proton exchange membrane fuel cell (PEMFC) output voltage is proposed in this paper. In addition, an optimal trajectory exploration large-scale multi-delay deep deterministic policy gradient (OTEL-MD3PG) algorithm, which naturally considers the baseline FOPID coefficients in the design objective and provides the online coefficient adjusting ability through learning, is designed as the tuner of the controller to improve adaptability and robustness. This algorithm adopts the optimal trajectory exploration policy, whereby a new agent (demonstrator) generates demonstration samples that instruct the agent to learn, and another agent (tracker) adds noise to the action of the demonstrator to explore the limits of its control trajectory, thereby obtaining a more robust control strategy. The simulation results show that this proposed algorithm offers a rapid response, strong anti-interference, and excellent control performance.