Output Voltage Regulation Research Articles

Passivity‐based control for a DC/DC high‐gain transformerless boost converter

AbstractIn this work, an adaptive passivity‐based controller for a DC‐DC high‐gain transformerlessdouble‐inductor boost converter is fully detailed. The proposed current‐mode control scheme results in two feedback loops, a current controller for tracking the inductor current considering damping injection and energy shaping, and a voltage loop composed by a proportional‐integral action to guarantee output voltage regulation. Furthermore, a parametric uncertainty estimator using immersion‐invariance approach is designed to improve the robustness of the current loop. As a result, a multi‐loop adaptive nonlinear energy‐based controller, which ensures regional asymptotic stability via Lyapunov analysis is accomplished. In addition, considering practical conditions, real‐time numerical simulations, using a 1 kW case‐study converter, are carried out in order to assess the effectiveness of the proposed control scheme. Results for output voltage regulation, current tracking, and parametric uncertainty estimation under input voltage and load step changes are shown.

Pendulum energy harvester with torsion spring mechanical energy storage regulator

This paper presents the integration of a novel mechanical torsion spring regulator into a pendulum energy harvester system. This regulator was designed to provide the same voltage-smoothing benefits of a flywheel without the start-up issues caused by increasing system inertia. In addition, the introduction of the spring between the input and output stages of the device acts as a buffer for any sudden impacts, which not only allows the energy from such events to be fully absorbed and dissipated slowly through the output but significantly reduces the torque stress and torque fluctuation stress on critical components to improve the reliability of the system. Through experimentation and simulation, the transducer was shown to reduce the voltage fluctuation range from 13.85 to 28.16 V to 16.41 to 23.59 V for the pendulum energy harvester at resonance, and comparison of start-up response to that of a device with a flywheel shows a significant improvement in initial acceleration of the output when subjected to excitation. The energy harvester with spring has demonstrated a maximum normalised average power output of 12.09 W/g2, a maximum normalised average voltage of 109.96 V/g, and a maximum normalised power density of 7.8 W/g2/kg, at a resonant frequency of 1.2 Hz. The effectiveness of the spring mechanism for regulating output voltage and power, improving start-up performance, and reducing stress on critical components has significant implications for the real-world viability of pendulum energy harvesters, with the potential to improve their reliability in often unpredictable environments.

Comparison of sliding mode controller application for buck-boost converter based on linear sliding surface

In the utilization of photovoltaic (PV), the output voltage produced is unstable because the conditions of irradiation received by PV is not uniform. Therefore, a direct current (DC) voltage converter is needed as an output voltage regulator. In this research, buck-boost converter is proposed to regulate the desired output voltage. The proposed controller in this research is a sliding mode controller (SMC) and employ a linear sliding surface to maintain the regulated voltage stable. This research was conducted by determining the component parameters and state space model of the buck-boost converter. Proportional integral derivative (PID) controller with integral of time-weighted absolute error (ITAE) method is used as a comparison of the proposed method. The performance results were observed from the buck-boost converter by performing 3 fault scenarios, variation in supply voltage, resistor in load side, and the desired output voltage. The results obtained of SMC has a faster settling time than PID controller. The voltage deviation of buck-boost converter exhibits that SMC is smaller than the PID control. In addition, under some experiment conditions, the PID control could not or did not fit in some scenarios while the output control values of SMC matched the changes in the entire scenarios.

Robust control technique in power converter with linear induction motor

Induction motors are widely used in industrial applications as actuators, thanks to their simplicity of construction, which is subsequently reflected in low-cost maintenance. This paper shows the behavior of a three-phase power converter with a linear induction motor (LIM) as load, using a quasi-sliding control technique for output voltage regulation and a new control technique to control chaos. Digital pulse width modulation (DPWM) techniques are widely used to control electronic power converters. The controller proposed in this paper was designed using zero average dynamic (ZAD) and fixed point inducting control (FPIC) techniques. The ZAD-FPIC control strategy was designed and applied to a three-phase converter with linear induction motor load. Since it is not possible to measure the secondary currents, a secondary current observer was included in the system. Finally, bifurcation diagrams are shown as a technique for tuning controller parameters in ZAD-FPIC controllers. For the illustration of numerical results a simulation of the linear induction motor drive controlled was made by MATLAB/Simulink. The designs were tested in a rapid control prototyping (RCP) system based on digital signal processing (DSP) for dSPACE platform, using the 1103 controller card and control desk interface.

Control of a Modified Switched-Capacitor Boost Converter

Switched-capacitor converters and their alternatives have been shown to provide high efficiency with high power densities on smaller volumes, and can thereby be a suitable choice for energy harvesting. This paper proposes a hybrid power architecture based on a switched-capacitor topology and a boost converter that can be used for such purposes. A switching capacitor circuit can achieve any voltage ratio, allowing a boost converter to increase the input voltage to higher voltage levels. The first stage is unregulated with high-efficiency voltage conversion. The boost stage provides a regulated voltage output on such a converter. Rather than cascading two converters, their operation is integrated for the output voltage regulation. One major problem of switched-capacitor converters is output voltage regulation, which is solved by the interconnection of the power stages. The simplicity and robustness of the solution provide the possibility to achieve higher voltage ratios than cascading boost converters and provide higher efficiency. The converter’s size and cost can be improved with the integration of switching capacitors in DC-DC converter structures. A converter prototype has been designed, modelled, and built for the input voltage level of 2 V and power level of 5 W.

Minimization of Circulating Currents in Parallel DC-DC Boost Converter Using Non-Linear Droop Control for Battery Energy Storage System

Battery is considered the most dominant energy storage device for renewableenergy-based DC microgrid systems (RE-DCMG) because of its ability tostore energy for a longer duration. Here the power electronic converter playsa vital role, which acts as a bridge between the energy storage system and DCmicrogrid. One of the main reasons for the failure of battery systems due tothe failure of the power electronic converters. To improve the redundancy andconverter failure issues of battery energy storage systems (BESS), paralleloperation of multiple converters are required. However, the parallel operationfaces an issue of voltage imbalance between the converters which gives rise toan input circulating current. To address these issues, in this paper, we proposea nonlinear droop control based parallel DC-DC boost converter for battery energy storage system. The nonlinear droop control strategy ensures theequal battery current sharing between the parallel converters and good outputvoltage regulation. Moreover, SOC based controller avoids over-charging andover-discharging of the battery and the parallel converters ensure the redun-dancy in operation. The proposed system is designed and implemented in theMATLAB/Simulink and compared with the existing linear droop control.

Design and development of multiphase buck converters for voltage regulator modules

<p>Modern microprocessors in high-power applications require a low input voltage and a high input current, necessitating the use of multiphase buck converters. As per microprocessor computing complexity, the power requirements of the switching converter will also be more important and will be increasing as per load demand. Previous studies introduced some methods to achieve the advantages associated with multiphase regulators. This paper presents an effective closed closed-loop control scheme for multiphase buck converters that reduces ripple and improves transient response. It is suitable for applications that require regulated output voltage with effectively reduced ripple. The analysis began with a simulation of the entire design using the OrCAD tool, followed by the construction of a hardware setup. Experiments on a 200 Khz, 9 V, 12 A, 2-phase buck voltage regulator were conducted and the proposed experiment found to be useful.</p>

Design and Analysis of a Voltage-Mode Non-Linear Control of a Non-Minimum-Phase Positive Output Elementary Luo Converter

The positive output elementary Luo (POEL) converter is a fourth-order DC–DC converter having highly non-linear dynamic characteristics. In this paper, a new dynamic output voltage feedback controller is proposed to achieve output voltage regulation of the POEL converter. In contrast to the state-of-the-art current-mode controllers for the high-order boost converters, the proposed control strategy uses only the output voltage state variable for feedback purposes. This eliminates the need for the inductor current sensor to reduce the cost and complexity of implementation. The controller design is accompanied by a strong theoretical foundation and detailed stability analyses to obtain some insight into the controlled system. The performance of the proposed controller is then compared with a multi-loop hysteresis-based sliding-mode controller (SMC) to achieve the output voltage-regulation of the same POEL converter. The schemes are compared concerning ease of implementation, in particular, the number of state variables and current sensors required for implementation and the closed-loop dynamic performance. Experimental results illustrating the features of both controllers in the presence of input reference and load changes are presented.

Quasi Single-Stage Three-Phase Filterless Converter for EV Charging Applications

This paper presents a novel converter concept of the off-board electric vehicle (EV) charging, which is based on an unfolding rectification approach where the three-phase Vienna rectifier-based unfolder (VRU) is followed by two identical isolated current-source converter (CSC) modules in input-series output-parallel configuration. The VRU operates at low frequency and thus features negligible switching losses, while the CSCs are responsible for the synthesis of the high-quality sinusoidal grid current and output voltage regulation. The proposed configuration features two time-varying soft DC-links, thus no bulky electrolytic capacitors are required. Input inductors of the CSCs limit the input current ripple, eliminating the need for separate grid filter inductors. Another notable advantage lies in the simplicity of the control system. Each CSC operates at a fixed frequency and provides the required current wave-shaping using only a single independent control variable, while no high-frequency synchronization between the two modules is required. The proposed configuration features a modular structure and was verified with a 5 kW experimental prototype based on two identical 2.5 kW dc-dc modules and a common unfolding stage. During the experiments, the system provided power factor above 0.97 and THD below 5%. At rated power, the maximal efficiency of 94.8% was obtained.

Sliding-Mode Control of a Quadratic Buck Converter With Constant Power Load

This paper analyzes for the first time a two-loop sliding-mode control (SMC) of a high-order converter supplying a constant power load (CPL). The converter is a single-switch quadratic buck structure (QBC) interfacing a domestic 380 V DC bus to a CPL requiring a regulated voltage of 48 V DC. The converter is unstable in the absence of control and even after the insertion of an inner loop based on SMC of the input inductor current. The addition of an appropriate linear outer loop establishing the reference to the inner loop stabilizes the system and provides output voltage regulation. The regulated QBC shows a fast recovery of the output voltage with negligible overshoot in response to step-type changes of the output power or the input voltage. It is also shown that the implemented regulator for CPL supply can be used directly in the case of a constant current load (CCL) or a constant resistance load (CRL) resulting in similar performance to the CPL case. PSIM simulations and experimental results in a 400 W prototype are in good agreement with theoretical predictions.

Evaluation and Perspective of Analog Low-Dropout Voltage Regulators: A Review

Low-dropout regulators (LDOs) are widely adopted in power management integrated circuits (PMICs) and serve as a bridge between the switching regulators and individual on-chip modules to provide a smooth, regulated output voltage. Compared to digital LDOs (DLDOs), analog LDOs (ALDOs) lead in the advantage of low output ripple and large power supply rejection (PSR). However, the preference of achieving high performance in terms of load transient, high PSR, good load and line regulation, while maintaining a low quiescent current and low dropout voltage for high efficiency, remains the key challenge in ALDO design. For operation with a low quiescent current, the bandwidth is reduced due to low transconductance, resulting in the limited gate driving capabilities in terms of charging and discharging the large gate capacitance of the pass or output transistor. In addition, the preference for system-on-chip design in the absence of large off-chip capacitors arises stability issues. In this paper, recent reported state-of-the-art architectures for ALDOs are revisited and reviewed. The performance of these ALDOs is compared and their applications are investigated.

Soft switched DC-DC converter for hybrid power generation photo voltaic panels using fuzzy logic controller

Maximum Power Point Tracking (MPPT) with a Z source cascaded inverter based on Fuzzy Logic Control (FLC) is proposed in this research for a hybrid photo-voltaic (PV) and wind turbine (WT) system. In the absence of PV or WT power generation, the suggested system offers an uninterrupted power supply to the grid. PV functions as a current source and creates maximum power at maximum power point (MPP), supplying just the deficiency power. This FLC-integrated technique minimises the complexity of typical PID controllers while also improving overall performance. To reduce switching losses, current, and voltage switching stress, a traditional dc/dc boost converter with soft switching has been introduced. To reduce switching stress, a boost converter with zero voltage switching is used. This research focuses on a Zero Voltage Switching (ZVS) technique that uses fuzzy logic control to meet the PV system's MPPT and output voltage regulation requirements. All these PV and wind hybrid systems, a Z-Source network, and a five-level cascaded inverter are part of the proposed topology. The advantages of a Z-source inverter outweigh the disadvantages of a traditional voltage-source inverter. The required stepped output voltage is achieved by boosting the DC link voltage from the PV system using a shoot through state. The suggested system has been simulated with MATLAB/SIMULINK, and the closed loop control technique has been investigated and verified.

Hybrid-Mode PFM Control for LLC Resonant Converter

This article presents a new hybrid-mode pulse-frequency-modulation control method for an <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">LLC</i> resonant converter. In the proposed control method, the primary-side resonant current sensing signal of the current-mode control variable is combined with a ramp signal of the voltage-mode control variable to determine an operating frequency. Then, the proposed control method mainly modulates the ramp signal in accordance with the output load condition. Therefore, the control-to-output voltage transfer function has both the current <bold xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">-</b> mode control and voltage-mode control characteristics that provide fast frequency response and stable output voltage regulation in a light-load condition. In addition, since the ramp signal is also used for slope compensation of the resonant current sensing signal, an external slope compensation circuit is not required. A small-signal ac modeling and loop analysis of the proposed method verify the advantages. The proposed control method is implemented into a field programmable gate array (FPGA) board with an analog front-end board. An experiment is carried out on a 288-W <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">LLC</i> resonant converter. The result shows that the proposed control method provides fast dynamic performance and stable operation under a light-load condition without an additional slope compensation circuit.

Inrush Current Management During Medium Voltage Microgrid Black Start With Battery Energy Storage System

This paper addresses the black start of medium voltage distribution networks (MV-DNs) by a battery energy storage system (BESS). The BESS consists of a two-level voltage source inverter interfacing MV-DN which has limited overcurrent capability. On the other hand, MV-DN normally includes several step-up and step-down transformers that are drawing sympathetic inrush current in energizing stage. Therefore, the major difficulty to perform black start by BESS during MV-DN island operation lies in the fact that the inverter has to simultaneous control the network voltage and its output current. This paper presents two control approaches for a BESS in order to control the inrush current during MV-DN black start. The proposed control schemes consist of droop, voltage and current loops in the stationary reference frame. The droop loop is used to generate the voltage reference. An intermediate voltage and inner current loops are designed for output voltage regulation, current reference generation as well as current tracking, respectively. New reference modifiers are included into droop and voltage loops to limit inrush current. The proposed control schemes are experimentally tested for energizing Ingå MV-DN in Finland by 1 MVA BESS, and their performance is compared in terms of inrush current value and voltage quality. The obtained results prove that both methods are able to feed the load with a fixed voltage in the steady-state as well as to limit the transformer inrush current considering the inverter overcurrent limit.

Sliding Mode Control-Based MPPT and Output Voltage Regulation of a Stand-alone PV System

Abstract When it comes to reducing emissions caused by the generation of electricity, among different renewable energy sources, the solar energy gains prominence, due to its geographical availability, simplicity of implementation, and absence of physical moving parts. However, the performance of photovoltaic systems is dependent on environmental conditions. Depending on temperature and solar irradiation, the photovoltaic (PV) system has an operating point where maximum power can be generated. The techniques that are implemented to find this operating point are the so-called maximum power point tracking (MPPT) algorithms. Since weather conditions are variable in nature, the output voltage of the PV system needs to be regulated to remain equal to the reference. Most of the existing studies focus either on MPPT or on voltage regulation of the PV system. In this paper, the two-stage PV system is implemented so that both MPPT and voltage regulation are achieved simultaneously. Additionally, an improved version of the perturb and observe (P&amp;O) algorithm based on artificial potential fields (APF), called APF-P&amp;O, is presented. According to the results of the simulations carried out in MATLAB/Simulink software, the APF-P&amp;O method is more efficient than the conventional method.

Second-Order Rotating Sliding Mode Control With Composite Reaching Law for Two Level Single Phase Voltage Source Inverters

In the recent past, the integration of distributed generation via power electronic interface like voltage source inverter (VSI) allows attaining the desired voltage quality by adopting appropriate control law. This paper presents sliding mode control (SMC) with composite reaching law technique for regulating output voltage under variable load conditions for single phase VSI. Inherent properties of SMC like robustness are achieved usually at the cost of chattering along the sliding surface. To handle this trade-off, optimal sliding surface selection mechanism is applied with adoptive reaching law based on state variables magnitude to set the value of control gain. The novelty of the proposed technique is related to composite reaching law that overcomes constraints associated with SMC. The proposed reaching law is a combination of exponential, power, and difference function. The intelligent mix of these functions makes the suggested reaching law more effective in achieving a high-speed convergence rate of system states and significant chattering reduction. Moreover, the sliding surface is chosen using a time-varying slope based on error variables. Comparative study of SMC with cosine exponential reaching law (Cos-ERL) results, fractional power rate reaching law (FPRRL) and proposed composite reaching law with rotating sliding surface(C-RL-RSS) applied on single phase voltage source inverter under variable load conditions validates the effectiveness of the proposed C-RL-RSS based SMC. It is revealed that the proposed C-RL-RSS based SMC is proficient in achieving very low %THD in the output voltage along with reduced chattering and minimum tracking time.

A Moth-Flame Optimized Robust PID controller for a SEPIC in Photovoltaic Applications

The paper presents a robust proportional integral derivative (PID) controller improved by the metaheuristic moth-flame optimization (MFO) technique for a DC-DC single-ended primary inductor converter (SEPIC) to achieve aimed user output performance in photovoltaic systems. Having non-linear dynamics, SEPIC with the conventional linear PID controllers possessing constant tuning gains cannot exhibit robust performance under the input and load variations. To confront the problem, a process-adaptive PID controller, whose tuning gains are adjusted by the MFO algorithm to ensure the continuity and stability of output voltage and the power, is designed and simulated. Comparative performance analysis of MFO tuned PID controller compared with the classic PID controller is conducted. The simulation results reveal a substantial performance improvement of the MFO-PID controller over the traditional PID controller in terms of maintaining constant regulated output voltage and having excellent setpoint tracking capability with minimal settling times and overshoot under considerable input and load disturbances.

An IDA-PBC Design with Integral Action for Output Voltage Regulation in an Interleaved Boost Converter for DC Microgrid Applications

This paper describes the output voltage regulation control for an interleaved connected to a direct current (DC) microgrid considering bidirectional current flows. The proposed controller is based on an interconnection and damping passivity-based control (IDA-PBC) approach with integral action that regulates the output voltage profile at its assigned reference. This approach designs a control law via nonlinear feedback that ensures asymptotic stability in a closed-loop in the sense of Lyapunov. Moreover, the IDA-PBC design adds an integral gain to eliminate the possible tracking errors in steady-state conditions. Numerical simulations in the Piecewise Linear Electrical Circuit Simulation (PLECS) package for MATLAB/Simulink demonstrate that the effectiveness of the proposed controller is assessed and compared with a conventional proportional-integral controller under different scenarios considering strong variations in the current injected/absorbed by the DC microgrid.

Robust nonlinear control of a quasi‐resonant DC‐DC converter with turn‐on and turn‐off zero current switching

In this paper, a new robust control strategy is proposed to regulate the output voltage of a quasi-resonant converter. The proposed approach completely eliminates the switching losses and the electromagnetic interferences due to high current changing rates. The circuit structure is simple and affordable and does not have many auxiliary switches. The regulated output voltage of a buck converter must be robust to input voltage variations. Moreover, the controller must be robust to the circuit parameter uncertainties. In this paper, a new control strategy with nonlinear structure is used with the advantage of robustness, and turn-on and turn-off zero current switching. The robustness of the converter to the input voltage variations and the parameter uncertainties is investigated. The new proposed control strategy can be implemented using different controller types. Therefore, a comparison between the proposed nonlinear controller and a conventional PI controller, which is most widely used in practice, is performed. The simulation results show the efficiency and robustness of the proposed method. Finally, the simulation results are verified by the experimental tests.

Development of a Digitally Controlled Inductive Power Transfer System with Post-Regulation for Variable Load Demand

Inductive Power Transfer (IPT) is an emerging technology enabling a contactless charging process in manifold applications such as electric vehicles, wearable and portable devices, or biomedical applications. Such technology can be profitably used to develop enhanced electronic solutions in the framework of smart cities, homes and smart workplaces. This paper presents the development and realization of a series–series compensated IPT System (IPTS) followed by a post-regulator implemented by means of a DC–DC converter. Such a system is modeled through a first harmonic approximation method, and a sensitivity analysis of the IPTS performance is carried out with respect to the variations of the primary inverter switching frequency and phase-shift angle. As an element of novelty of this work, the bias points are determined which allow the efficiency maximization while ensuring system controllability. An enhanced dynamic modeling of the system is then performed by means of a coupled mode theory, including the inverter phase-shift modulation and extending its validity to whatever operating frequency. A digital control of the post-regulator is implemented by means of a commercial low-cost microcontroller enabling the output voltage regulation under both fixed and variable load conditions through a voltage mode control technique. An IPTS prototype is eventually realized, which is able to correctly perform the output voltage regulation at the desired nominal value of 12 V for static resistive loads in the range [5, 24] Ω, yielding the output power in the range [6, 28.8] W and the experimental efficiencies going from 72.1% (for 24 Ω) to 91.7% (for 5 Ω). The developed system can also be effectively used to deliver up to 35 W output power to variable loads, as demonstrated during the battery charging test. Finally, an excellent output voltage regulation is ascertained for load transients between 5 Ω and 24 Ω, with limited over- and undershoot amplitudes (less than 3% of the nominal output voltage), thus enabling the use of the proposed system for both fixed and variable loads in the framework of smart homes and workplaces applications.