Output Voltage Regulation Research Articles

Performance numerical evaluation of modified single-ended primary-inductor converter for photovoltaic systems

<span lang="EN-US">Single-ended primary-inductor converter (SEPIC) was considered a good alternative to a DC-DC converter for photovoltaic (PV) systems. The SEPIC converter can operate with an input voltage greater or less than the regulated output voltage, or as a step-up or step-down. As a step-up converter, SEPIC boosts PV voltage to specific levels. However, gain limitation and voltage stress continue to reduce the efficiency of conventional SEPIC converters. Because of this, researchers created a modified SEPIC converter to improve performance. In this paper, six modified SEPIC converters were compared and evaluated. To compare fairly, all modified SEPIC converters are non-isolated and use a single switch. Power simulator (PSIM) software was used to simulate each converter with a BISOL BMO-250 PV module and maximum power point tracking (MPPT) P&O controller. The converter with the highest static voltage gain and lowest duty cycle has been identified. It results in up to ten times voltage increment with a 0.8-duty ratio. All topologies have the same voltage stress, with maximum and minimum values of 30.1 and 29.5 V, respectively. On the other hand, each topology produces different average efficiencies, with the highest and lowest efficiency at 99.5% and 97.2%, respectively.</span>

Voltage Regulating Strategy of a New LCC/S+L Inductive Power Transfer System

In the voltage control of the inductive power transfer (IPT) system, a cascaded DC-DC converter is normally adopted which reduces the power density. However, the wireless communication between the transmitter and the receiver may lead to a delay of control as well as communication instability. This paper proposes a new LCC/S+L resonance topology for the IPT system, which can realize single-stage voltage regulation on the receiving side with both buck and boost capability. Based on the fundamental wave analysis method, this paper analyzes the working principle of LCC/S+L resonant topology. Then the control strategy of the phase shift angle between bridges and within bridges is obtained by the voltage of both ends of the series inductor and the load voltage vector. It is verified by simulation that the proposed new resonance topology and control strategy can achieve output voltage regulation of 300-500 V with a constant 375 V input DC voltage.

Fast Transient State Trajectory Control for Switched-Capacitor-Based Resonant Converter

This paper presents a state trajectory control scheme for switched-capacitor-based resonant converter consisting of two half-bridge circuits with four switches. The proposed technique can not only bring improved dynamic response of output voltage regulation, but ensure that the converter benefits from soft-switching operation. The analysis in the two state planes provides insight into the switching modes of the converter and creates an accurate behavior framework in the geometrical domain. As a result, a finite state-machine controller is designed based on the planning of the state trajectories. The switching conditions are exploited to obtain fast start-up and step-load transient responses. The proposed control method is verified with experimental results of a 14.5V, 5.8A converter prototype.

O Splines-Based Fixed-Frequency Integral Sliding-Mode Controller for PFC Rectifier

This paper proposes a fast-response sliding mode controller (SMC) for a semi-bridgeless boost converter under large and quick load fluctuations to ensure tight output voltage regulation and unity power factor correction (PFC) at the line side. In this sense, a novel approach for estimating the reference current profile is presented focusing on the real-time phasor estimation via the O-splines of the discrete-time Taylor-Fourier transform (DTTFT). This method allows for improving the computational efficiency and dynamic performance of the estimations of amplitude, frequency and phase of the network voltage used for the generation of the reference current profile. Several aspects of the controller design are discussed, including the choice of the sliding surface, the existence and stability conditions, and the implementation of an adaptive hysteresis band to fix the switching frequency and reduce zero-crossing distortion. Experimental results of a GaN-based prototype validate the theoretical predictions, exhibiting a PF close to 1 and a total harmonic distortion lower than 3.2% in presence of load changes of up to 50% and changes in the output voltage set point. Several comprehensive experimental comparisons between the proposed framework and the most widely used methods recently reported in the literature are accomplished in terms of transitory and steady-state responses. The robustness of the proposed control approach is experimentally demonstrated under sag conditions and a wide operating range of the input voltage.

A robust voltage control of dual active full bridge converter based on RBF neural network sliding mode control with reduced order modeling approach

This paper presents a control method of dual active full bridge (DAB) DC/DC converter based on neural network Sliding mode control under the reduced order modeling method, which is used to enhance the output voltage regulation and improve the system robustness. Sliding mode control (SMC) is famous for its robustness and improving the dynamic performance of nonlinear systems. However, it includes drawbacks such as complex modeling, chattering, and decreased tracking performance. Therefore, through the method of reduced order modeling, the Radial Basis Function neural network algorithm is selected to modify and design the traditional sliding mode variable structure controller, completing the design of neural network approximation terms and adaptive laws. The proposed reduced order modeling and RBF(Radial Basis Function Neural Network)-SMC scheme simplifies the dual active full bridge modeling process, completes the parameter approximation of the sliding mode controller, and eliminates the chattering problem. Firstly, through simulation and comparative analysis of commonly used modeling methods for dual active full bridge, a reduced order modeling method was adopted to simplify the design process. Then, by ingeniously designing the sliding mode surface and Radial Basis Function control law, and using neural network to modify the Sliding mode control technology, the chattering problem, load disturbance and voltage fluctuation influence of the sliding mode controller are improved. The stability of the control method is proved by Lyapunov stability theory. Finally, the proposed RBF-SMC method is compared with PI linear control and classical Sliding mode control methods through simulation and experiments to verify the effectiveness of the proposed control method.

Barrier function based adaptive sliding mode controller for the hybrid energy storage system of plugin hybrid electric vehicles

This paper proposes a hybrid energy storage system (HESS) and smart charging mechanism for plug-in hybrid electric vehicles (PHEVs) with the aim of reducing greenhouse gas emissions and fossil fuel consumption. The HESS includes a battery as the main energy source and an ultra-capacitor (UC) as an auxiliary source. Both the power sources are connected to the DC bus through power conditioning circuitry. To regulate the system’s output variable, a barrier function-based adaptive sliding mode controller is proposed, which will achieve finite-time convergence and robustness against disturbances and uncertainties without requiring prior knowledge of the upper bounds of the system. The controller aims to reduce chattering and ensure various control objectives, such as tight regulation of output voltage, perfect tracking of reference currents for the UC and battery, and power factor correction in the grid-to-vehicle (G2V) mode. Simulation results using MATLAB/Simulink show that the proposed controller outperformed sliding mode control (SMC) and finite-time synergetic control (FTSC). The proposed strategy has been validated through real-time hardware-in-the-loop (HIL) experiments using C2000 Delfino Microcontroller F28379D Launchpad.

Design and Implementation of Single-Phase Boost PFC Converter

In this paper, a single-phase boost type ac-dc converter with power factor correction (PFC) technique is designed and implemented. A current mode control at a constant switching frequency is used as a control strategy for PFC converter. The PFC converter is a single-stage singleswitch boost converter that uses a current shaping technique to reshape the non-sinusoidal input current drawn by the bulky capacitor in the conventional rectifier. This technique should provide an input current with almost free-harmonics, comply with the IEC61000-3-2 limits, and a system operates with near unity power factor. The other function of the boost converter that should beaccomplished is to provide a regulated DC output voltage. The complete designed system is simulated in MATLAB/SIMULINK and a hardware prototype has been built using analog devices. Simulation results and experimental results are presented to validate the proposed system.

Model predictive control for solid state transformer

The solid-state transformer (SST) is being presented as a technology that enables the construction of new power systems due to its many advantages. These benefits include reduced weight and volume compared to traditional transformers, power factor compensation, accurate output voltage regulation, harmonic mitigation, short-circuit current limitation, and voltage dip immunity, under certain conditions. Unlike other studies that only demonstrated the effectiveness of Model Predictive Control (MPC) in individual parts of the SST, this study shows the control of an entire SST using the MPC strategy. The performance of the SST during power system transients is evaluated to showcase the features of the SST by predictive control.

Output voltage regulation of a fuel cell/boost converter system with uncertain load: An adaptive PI‐PBC approach

SummaryIn this article, we consider the problem of voltage regulation of a proton exchange membrane fuel cell connected to an uncertain load through a boost converter. We show that, in spite of the inherent nonlinearities in the current‐voltage behavior of the fuel cell, the voltage of a fuel cell/boost converter system can be regulated with a simple proportional‐integral (PI) action designed following the passivity‐based control approach. The system under consideration consists of a DC–DC converter interfacing a fuel cell with a resistive load. We show that the output voltage of the converter converges to its desired constant value for all the systems initial conditions—with convergence ensured for all positive values of the PI gains. This latter feature facilitates the, usually difficult, task of tuning the gains of the PI. An immersion and invariance parameter estimator is afterward proposed which allows the operation of the PI passivity‐based control when the load is unknown, maintaining the output voltage at the desired level. The stable operation of the overall system is proved and the approach is validated with extensive numerical simulations considering real‐life scenarios, where robust behavior in spite of load variations and the presence of noise is obtained.

High-efficiency bidirectional resonant WPT system for electric vehicles

<p>The wireless power transfer (WPT) system has become popular given its safety and flexibility in electric vehicle (EVs) charging applications. Due to the increasing number of EVs, vehicle to grid (V2G) can be implemented in the future in which a bidirectional WPT is one of the key features. A high-efficiency bidirectional resonant WPT system is studied and implemented in this study. Besides bidirectional capability, single stage and regulated output voltage are other features of this work. It is done by using the variable frequency control without sacrificing efficiency and conforming to the typical frequency range of the WPT system for EVs application. The analysis of the series-series compensated WPT is presented, followed by the design consideration of the developed bidirectional WPT system. At last, the implementation and experimental results for a 3 kW laboratory prototype are also presented to show the validity and the feasibility of the proposed scheme. A 96.8% efficiency at a 210-mm gap and a 95% efficiency at a 250-mm gap can be achieved under a rated power condition.</p>

Auxiliary Power Supply for Input-Series Output-Parallel Medium-Voltage Solid State Transformers

Auxiliary power supply (APS) is an essential component of medium voltage (MV) solid state transformers (SSTs) feeding the auxiliary units, such as gate drivers, controllers and sensors. Usually APSs are obtained from the distributed bus, which may cause the input voltage imbalance before the main power transmission. This paper proposed a new design for isolated APS of an input-series output-parallel (ISOP) SST. The designed distributed MV APSs are galvanically isolated by flybacks, and the centralized APS on the low voltage (LV) side is supplied from the MV APSs via a decoupling four-port medium frequency transformer (MFT) with high isolation voltage. To solve the issue of input voltage imbalance posed by the ISOP system, a dual-loop control scheme based on APS-fluctuating is proposed, which can realize output voltage regulation (OVR) and input voltage sharing (IVS) simultaneously. The small-signal model, start-up strategy and parameter design of the proposed system are investigated. Finally, a 500 V/2.2 kW lab prototype of SST with APS has been built and the overall system efficiency reaches 95.1%.

An Improved One-to-Three WPT System With Tunable Compensation Network and Enhanced Pulse Density Voltage Control

In order to realize selective power transfer and output voltage regulation of LCC-S compensated one-to-three wireless power transfer (WPT) system, a novel control strategy based on dual switch-controlled capacitor (DSCC) and enhanced pulse density voltage control (EPDVC) is proposed in this paper. The improved series compensation network increases the selectivity of the receivers. Then, by introducing the DSCC into the LCC topology, both the load-independent current in the transmitting coil and the zero voltage switching (ZVS) of the inverter are maintained under different operating frequency. Besides, the common phase shift modulation (PSM) used to regulate the output voltage is substituted by a novel pulse density control strategy to overcome the hard switching issue when the system operates at light load. To verify the theoretical analysis, a 200-W prototype with 50-V input voltage is built and tested. The experimental results validate the selectivity of the one-to-three WPT system and the feasibility and stability of the proposed control strategy based on dual SCC and EPDM. The inverter achieves ZVS within the whole output power range under different operating frequencies and the peak efficiency reaches 90.57% with resistive load.

Voltage Control Strategy for Improving Disturbance Rejection Performance in Stationary Reference Frame During Parallel Operation of Multimodular UPS

This paper proposes a voltage control strategy to improve the disturbance rejection performance during the parallel operation of multi-modular uninterruptible power supply (UPS). In the standalone operation of UPS, feed-forward control can improve the dynamic performance of output voltage regulation. However, a circulating current can occur when feedforward control is applied in the parallel operation of UPS modules, causing uneven load sharing among the modules. In this study, the reason for the occurrence of the circulating current was analyzed using a circulating current impedance model. A partial feedforward control technique was proposed, which compensates for a portion of the load current by considering the circulating current impedance in the parallel operation of the UPS. However, this reduced the disturbance rejection performance compared with the standalone operation of the UPS, which uses full feedforward compensation gain. Therefore, an additional feedforward control technique was proposed to enhance the disturbance rejection performance. The effectiveness of the proposed control strategy was verified through the experimental result of the parallel operation of 500 W modular double-conversion UPSs.

A multi-level rectifier with voltage balancing capability for EV charging

ABSTRACT In two-stage electric vehicle (EV) battery chargers, ac-dc conversion stage contributes significantly in determining the power quality. At this stage, multilevel rectifiers (MLRs) featuring switches with lower voltage rating and better input voltage waveform quality can be adopted. However, balancing capacitor voltage in MLR is an important challenge. In this paper, a single-phase five-level power factor correction (PFC) rectifier with self-balancing capacitor is implemented for EV battery charging. The complimentary switching scheme adopted for rectifier reduces number of gate driver circuits and ensures capacitor voltage balancing. The rectifier shows added benefit of reduced voltage stress across switches and not requiring an external filter at the dc side as the load is parallelly connected with one of the capacitors. The operating principle, control strategy, modulation technique and design features of the implemented five-level rectifier is discussed in detail. The implemented control scheme enhances rectifier performance by establishing precise output voltage regulation during load fluctuations while maintaining unity power factor at input side. The five-level rectifier is validated experimentally and compared with other existing multilevel and non-multilevel rectifier topologies. The peak efficiency of 93.8% is achieved at 2 kW of output power.

State Feedback with Integral Control Circuit Design of DC-DC Buck-Boost Converter

The pulse-with modulated (PWM) dc-dc buck-boost converter is a non-minimum phase system, which requires a proper control scheme to improve the transient response and provide constant output voltage during line and load variations. The pole placement technique has been proposed in the literature to control this type of power converter and achieve the desired response. However, the systematic design procedure of such control law using a low-cost electronic circuit has not been discussed. In this paper, the pole placement via state-feedback with an integral control scheme of inverting the PWM dc-dc buck-boost converter is introduced. The control law is developed based on the linearized power converter model in continuous conduction mode. A detailed design procedure is given to represent the control equation using a simple electronic circuit that is suitable for low-cost commercial applications. The mathematical model of the closed-loop power converter circuit is built and simulated using SIMULINK and Simscape Electrical in MATLAB. The closed-loop dc-dc buck-boost converter is tested under various operating conditions. It is confirmed that the proposed control scheme improves the power converter dynamics, tracks the reference signal, and maintains regulated output voltage during abrupt changes in input voltage and load current. The simulation results show that the line variation of 5 V and load variation of 2 A around the nominal operating point are rejected with a maximum percentage overshoot of 3.5% and a settling time of 5.5 ms.

High-Frequency 12 V Regulated LLC Bus Converter With Integrated Multiphase Inverse Coupled Resonant Inductor

In the application of 48 V bus converter, the traditional multiphase regulated <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">LLC</i> converter has some shortcomings, such as insufficient gain range, low light-load efficiency, and difficult current sharing. In order to improve the performance, this article investigates a comprehensive design scheme of multiphase interleaved magnetic integrated <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">LLC</i> converter, which can extend the gain range and achieve active current sharing simultaneously. First, a new structure of multiphase inverse coupled resonant inductor and magnetic integrated transformer is proposed. Then, a high-precision magnetic circuit model is constructed to optimize the design of integrated inductor and transformer. On this basis, the three-phase interleaved magnetic-integrated <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">LLC</i> converter prototype is manufactured, which has a 36–75 V input voltage range and a 12 V regulated output voltage. In addition, the prototype can output 1080 W power in a quarter brick and has a power density of 716 W/in <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sup> . The maximum efficiency at rated input voltage is 97.5% and remains above 96% over the main input voltage range. As shown by the quantitative performance comparison results, the proposed converter is superior to other state-of-the-art solutions in terms of the comprehensive performance.

Impact of Space Vector Selection and Input Displacement Angle on Switch Voltage Stress of Current Source Rectifier

Three-phase current source rectifier (CSR) is concerned due to its flexible output voltage regulation, high reliability and fast dynamic response. Excessive voltage stress on the switch will increase the cost of the rectifier and reduce the reliability of the system. Therefore, it is essential to optimize the voltage stress of the switch. In this letter, the voltage stress of switch caused by each current vector in space vector modulation (SVM) is analyzed. Then, the vectors with low voltage stress are selected for combination to reduce the voltage stress of the switch without changing the topology. In addition, the vectors are re-optimized considering the effects of displacement angle. The re-optimized SVM can reduce the voltage stress by up to 13% under the leading or lagging power factor operation. Furthermore, the dc-link current ripple and modulation index range of different modulation methods are compared, and the effectiveness of the proposed modulation schemes are verified by experiments.

High Step-Up Gain Converter Based on Two-Phase Interleaved Coupled Inductor Without Right-Hand Plane Zero

This paper proposed a novel two-phase interleaved Coupled Inductor (CI) based high step-up gain converter without Right Half Plane (RHP) zeros for a wide operating range of duty cycle. A coupled inductor between input and output is used in the proposed converter to eliminate RHP zero. The energy of CI is transferred to output capacitor when switch is ON to eliminate RHP zero. Furthermore, the converter has a wide operating range to eliminate RHP zero with a coefficient coupling of CI near one. Thus, the converter achieves higher bandwidth and a wide range of control over output voltage. The small-signal model of proposed converter is derived to verify the proposed claim. The single loop voltage control is sufficient to regulate output voltage of the converter with a good stability margin and faster dynamic response for a wide range of load changes. In addition, proposed converter has a high voltage step-up gain and low voltage stress on switching devices compared to the boost converter. Moreover, interleaved operation at input side reduces ripple and increases power density. All theoretical findings are verified by simulation and experimental results. Experimental results are provided from implemented laboratory prototype of input voltage of 24 V to output voltage of 100 V and 200 W power.

Mode Switching Technique for High Efficiency Buck Converter

In order to achieve high efficiency in a wider load range, a PWM/PFM/Power-Saved mode dc–dc buck converter is proposed. The mode switching technique is based on an accurate power loss model consisting of critical components/parameters: The size of the power transistor and the ON/OFF status of power-hungry subcircuits. The circuit of mode switching technique is achieved by the reference, pulse skipped modulation (PSM) comparator and feedback resistors, and its own consumption of quiescent current is extremely low. At ultra-light load, by detecting the ZCD duration and the ripple of the output, the system can switch to the Power-Saved-Mode. The proposed buck converter was implemented by using a 0.18 [Formula: see text]m CMOS process. It achieves a peak efficiency of 97% and [Formula: see text]90% efficiency from 100 [Formula: see text]A to 600 mA. A 360 nA quiescent current is achieved. With a low output ripple of less than 60 mV, the input voltage range and regulated output voltage are 3.6–5 V and 1.2–3.3 V, respectively.

Konverter DC-DC Penstabil Tegangan Listrik Out Put Sel Surya Terhadap Perubahan Input Cahaya

The dc output voltage of the solar cell is regulated due to changes in the intensity of sunlight shining on the surface of the solar cell, so that in the treatment of storing the dc output voltage of the solar cell to an external electrical load energy saver becomes unstable. Testing the occurrence of regulation of the dc output voltage of the solar cell expressed as the Vo(cell) parameter is carried out by changing the distance of the white light intensity irradiation from the LED lamp to the surface of the solar cell. The research method of adding a dc-dc converter device to the output part of the solar cell produces a stable dc output voltage parameter from the dc-dc converter device. The results of the research on charging energy storage on HP charge batteries using (1) the output voltage supply without the dc-dc converter parameter Vo(cell) obtained the results of charging the electrical energy load of the hp charge battery at Wb1(bat.) = 1.408 watt.hours and ( 2) The use of the supply voltage output Vo(conv.) from the dc-dc converter results in charging the electrical energy load for charging the battery charge hp reaching Wb2(bat.) = 1.426 watt.hours. There is a difference in the length of time it takes for the results of electrical energy to fill the cell phone charge battery using an output voltage source supply originating from a dc-dc converter regulator compared to an output voltage source without using a dc-dc converter regulator.