One-cycle Control Research Articles

Analog One-Cycle Control Strategy for Stable Battery Charging in Photovoltaic Systems

The growing adoption of photovoltaic systems for direct electricity generation from solar radiation has underscored the importance of efficient energy storage solutions. Batteries are the predominant method for storing energy from photovoltaic systems, especially for applications such as electric vehicle (EV) charging. However, these systems face significant challenges, particularly regarding battery longevity, as fluctuations in solar irradiation can lead to harmful voltage spikes. This paper introduces an Analog One-Cycle Control (OCC) strategy designed to mitigate these issues by stabilizing the battery voltage against varying input voltages. The proposed control scheme aims to enhance battery life by preventing damage caused by voltage overshoots. Experimental results demonstrate the effectiveness of the OCC strategy in maintaining steady-state conditions and optimizing power management.

Unified One-Cycle Control for Fully Digitalized ZVS Four-Switch Buck–Boost Converter During Bidirectional Power Flow Transition

Unified One-Cycle Control for Fully Digitalized ZVS Four-Switch Buck–Boost Converter During Bidirectional Power Flow Transition

Novel cascaded switched-diode five level inverter for renewable energy integration

This research presents the usage of a unique five-level cascaded switching diode for medium voltage integration of renewable energy sources. Its primary purpose is to decrease the quantity of gate drivers and switches. In addition to that, the cost and space for the installation of multilevel inverters are less. The inverter topology of novel cascaded multilevel inverters and switched diodes will combine both benefits. One-cycle control (OCC), which is used for clock phase-shifting (CPS) to regulate a two-stage container security device (CSD) multilevel inverter of renewable energy integration, was created to address issues with the multilevel inverter's direct current (DC) source variations. The topology also provides efficiency, harmonic distortion reduction, and voltage output quality. Waveforms are created, and a robust resistance to DC source variations is attained. The viability of the unique five-level inverter using cascaded switched diodes is confirmed by discussing the results of both simulation and experiment.

Airport Microgrid and Its Incorporated Operations

This paper presents the development of an airport bipolar DC microgrid and its interconnected operations with the utility grid, electric vehicle (EV), and more electric aircraft (MEA). The microgrid DC-bus voltage is established by the main sources, photovoltaic (PV) and fuel cell (FC), via unidirectional three-level (3L) boost converters. The proposed one-cycle control (OCC)-based current control scheme and quantitative and robust voltage control scheme are proposed to yield satisfactory responses. Moreover, the PV maximum power point tracking (MPPT) with FC energy-supporting approach is developed to have improved renewable energy extraction characteristics. The equipped hybrid energy storage system (HESS) consists of an energy-type battery and a power-type flywheel; each device is interfaced to the common DC bus via its own 3L bidirectional interface converter. The energy-coordinated operation is achieved by the proposed droop control. A dump load leg is added to avoid overvoltage due to an energy surplus. The grid-connected energy complementary operation is conducted using a neutral point clamped (NPC) 3L three-phase inverter. In addition to the energy support from grid-to-microgrid (G2M), the reverse mcrogrid-to-grid (M2G) operation is also conductible. Moreover, microgrid-to-vehicle (M2V) and vehicle-to-microgrid (V2M) bidirectional operations can also be applicable. The droop control is also applied to perform these interconnected operations. For the grounded aircraft, bidirectional microgrid-to-aircraft (M2A)/aircraft-to-microgrid (A2M) operations can be performed. The aircraft ground power unit (GPU) function can be preserved by the developed microgrid. The MEA on-board facilities can be powered by the microgrid, including the 115 V/400 Hz AC bus, the 270 V DC bus, the switched-reluctance motor (SRM) drive, etc.

PV-MPPT-based one-cycle control of LV-DC-fed three-leg single-phase STATCOM for high-quality grid current

PV-MPPT-based one-cycle control of LV-DC-fed three-leg single-phase STATCOM for high-quality grid current

Linear–Assisted DC/DC Converters with Modified Current-Mode Control Applied to Photovoltaic Solar Systems

This article shows the proposal of a current-mode one-cycle control for linear-assisted DC/DC converters. Linear assisted DC/DC converters are structures that allow to take advantages of the two classic alternatives in the design of power supply systems: voltage linear regulators (classic NPN topology or LDO –low dropout–) and switching DC/DC converters. The current-mode one-cycle control technique is proposed in order to obtain the duty cycle of the linear-assisted converter switch. The proposed structure can provide an output with suitable load and line regulations. Thus, the paper shows the design and simulation results of the proposed current-mode one-cycle linear-assisted converter.

Global Maximum Power Point Tracking of Photovoltaic Systems Using Bio-inspired Algorithm-Based MPPT and One-Cycle Control

Global Maximum Power Point Tracking of Photovoltaic Systems Using Bio-inspired Algorithm-Based MPPT and One-Cycle Control

Cycle Skipping-Induced Bifurcation Analysis of Single-Inductor Bipolar-Output DC–DC Converters With One-Cycle Control

Due to strong nonlinear coupling effect amongst input/output ports and special cycle skipping effect, single-inductor bipolar-output (SIBO) DC-DC converters with one-cycle control may exhibit various bifurcation phenomena with complex border collision. This brief aims to investigate the cycle skipping effect and explore the occurrence mechanism of these nonlinear behaviors for stability improvement. On account of the cycle skipping effect, a set of the discrete-time mathematical expressions are derived to describe the dynamic characteristics of the one-cycle controlled (OCC) SIBO converter in discontinuous state space. Then, bifurcation analysis is performed by numerical simulation and eigenvalue trajectories. It is shown that cycle skipping effect activates more multi-cycle modes except single-cycle modes. Interestingly, the same slow-scale bifurcations in different operation region present various oscillatory form, which leads to hybrid-scale instability. Especially, the stability boundaries are presented in multi-mode space to guide optimal design. Finally, some experiment results are provided to verify the theoretical analysis.

One‐cycle controllability of high step‐up Boost converter with coupled inductor

SummaryComparing with traditional pulse width modulation technique, the transient performances of the high step‐up DC/DC converters can be significantly improved by one‐cycle control (OCC) technique, which is an appropriate control strategy for interface converters directly connecting the renewable energies to the DC microgrid. However, the suitability of OCC for these converters is rarely studied. One‐cycle controllability of the high step‐up DC/DC Boost converter with coupled inductor is studied with theoretical researches and experimental verifications. First, with the analysis on the operating modes of the converter, its periodic switched linear system model and the criterion for OCC are established. Furthermore, one‐cycle controllability of the converter is calculated in detail. Final, a prototype of the high step‐up converter from 48 to 380 V is prepared. Experimental results indicate that the disturbances in the input of the high step‐up converter can be depressed within only one switching cycle. Ideal dynamic characteristic for the converter under disturbance in the output is also achieved. Results of this paper are meaningful for investigations on the transient characteristics of high step‐up DC/DC converters applied to DC microgrid.

Bridgeless PFC Converter without Electrolytic Capacitor Based on Power Decoupling

Due to fewer conduction devices in operating condition, the bridgeless power factor correction (PFC) converter is more efficient than the traditional PFC circuit. However, to achieve a low output voltage ripple on the DC side, a large electrolytic capacitor must be connected in parallel to the output end. To reduce the value of capacitance, this paper proposes a dual-boost bridgeless PFC converter with a bidirectional buck/boost power decoupling converter in the latter stage. The bidirectional converter absorbs double-line-frequency ripple, lowering the power pulsation at the output end while realizing power decoupling. The one-cycle control is adopted in bridgeless PFC converter, so that the input current can follow the input voltage to achieve power factor correction and decrease harmonic pollution. The power decoupling circuit is designed with a voltage outer loop using PI control and a current inner loop using model predictive current control, which alleviates the output voltage fluctuation caused by the reduction of the capacitance value of the filter capacitor, for the purpose of realizing non-electrolytic capacitor. Finally, the topology and control strategy involved in this paper are simulated and experimented to verify the validity and superiority of the theory.

Dynamical Analysis of Hybrid-Scale Bifurcation in One-Cycle Controlled Single-Inductor Dual-Output Buck DC–DC Converters

In this paper, the hybrid-scale bifurcation evolutionary phenomena in one-cycle controlled (OCC) single-inductor dual-output (SIDO) Buck DC–DC converter are investigated thoroughly. First, the single-cycle and crossing-cycle iterative mapping models of the OCC SIDO converter in four operation modes are derived to describe the dynamical information under different topology switching sequences. Second, the evolutionary trend of hybrid-scale bifurcation behaviors is identified by numerical simulation. Third, bifurcation analysis based on the proposed models is performed by the trajectories of the eigenvalues, and significantly, the occurrence mechanism of hybrid-scale bifurcations in the evolutionary phenomena is explained in detail. And then, the participation factor is used to analyze the relationship between the variables and the eigenvalues. Especially, the relative parameter sensitivity of the iterative mapping model is proposed to evaluate the influence of such key parameters as load resistors on the eigenvalues so that plenty of design-oriented information will be provided to avoid the hybrid-scale bifurcation behaviors. Finally, PSpice circuit simulation and hardware experiments are carried out to verify the analysis results.

An Improved One-Cycle Control Algorithm for a Five-Phase Six-Leg Switching Power Amplifier in Active Magnetic Bearings

To achieve levitation in active magnetic bearing (AMB) systems, levitation coils must be driven by a switch power amplifier (SPA). Therefore, SPA performance is important to stable levitation. In previous studies, five-phase six-leg (5P6L) SPA topology was proposed to reduce hardware costs. However, current tracking performance degrades due to the coupling problem of the five-phase current and freewheeling loss. Then, the rotor may deviate markedly from the balance position, affecting rotor stability. The keys to solving these problems lie in the duty cycle control of the common leg and the compensation of freewheeling loss. This article proposes an improved one-cycle control (OCC) algorithm in which the duty cycle of the common leg is optimized by finite control set model predictive control (FCS-MPC), and the freewheeling loss is compensated for by a high-precision mathematical model. In addition, the parameter uncertainty of the FCS-MPC model is analyzed, and the convergence of the optimization algorithm is investigated. Simulations and experiments show that the proposed algorithm is effective, and the high dynamic response and low steady-state error performance of SPA are achieved.

Performance Analysis and Comparison of Non-Inverting Buck-Boost Converter Using PI, OCC, and Hybrid OCC-PI Control

The study compares and analyses the performance of the one-cycle control (OCC), hybrid one-cycle-proportional integral control (OCC-PI), and the conventional PI control method applied to the non-inverting buck-boost converter. The hybrid OCC-PI control method combines the OCC and PI control techniques to provide a hybrid non-linear closed-loop control technique for regulating the buck-boost converter. The MATLAB/Simulink equivalent system model was simulated with design parameter variations using a wide input voltage range of 9 – 36 V, a nominal output voltage of 28 V, and a fixed switching frequency of 250 kHz to validate the control response speed, reliability, and robustness of the proposed control technique. The simulation results due to input voltage, output voltage, and load variations were carried out whiles recording the settling time, overshoots, efficiency, output voltage, and inductor current ripples due to each applied control technique. The simulation results indicated that the Hybrid OCC-PI control provides better response speed and a lower output voltage overshoot relative to the PI. It also provides better reference voltage tracking compared to the OCC control method.

One-Cycle Control for Pulse Power Generator in Electrical-Discharge-Machining

Due to a short-time gap breakdown in electrical discharge machining (EDM), a high dynamic response and flexible discharge current control ability are required for a pulse power generator. Therefore, a one-cycle control(OCC) of output current for a buck-type EDM pulse power generator is proposed. Considering the inductor current operating state, a full-range OCC current control is presented, and the Taylor expansion method is used for the duty cycle calculation. A duty cycle optimization strategy is proposed for transient states. Based on the small signal modeling, the dynamic response ability of the system is analyzed. The discharge current can switch from many transient states to a steady state in a few switching cycles without a current overshoot, and follow the average current reference well in the steady state.

Performance Evaluation of Fuzzy One Cycle Control Based Custom Power Device for Harmonic Mitigation

Custom power devices (CPDs) provide better harmonic minimization when they are connected in parallel with the distribution network. Power switches have a hard impact on harmonic production in distribution networks, which leads to aging effects. Techniques used to control CPD’s provide full switching in various ways. A pulse width modulation (PWM) scheme requires a reference frame transformation that tracks source and load currents to produce a control signal. The voltage de-coupler is installed in the power device's current controllers to minimize fast current harmonics and remove complexity. One-cycle control (OCC) operates in dual boost converter mode and requires only source currents to produce a control signal. Minimum distortions are obtained by the output voltage feedback compensator. The proposed approach compares the performance of two methodologies based on total harmonic distortion (THD) analysis of the same grid voltage. The performance of the CPD using PI and fuzzy one-cycle control techniques is illustrated by simulation, which gives accurate results.

An Improved Swiss Rectifier and Its Nonlinear Control for Lower THD

Three-phase power factor correction (PFC) converters capable of step-down voltage are attractive in lower components voltage stress, and optimal design of following dcdc stage, which is an alternative for next-generation datacenter power conversion. An improved three-phase step-down PFC converter (swiss rectifier) based on harmonic-current-injection (HCI) concept is proposed. It improves input current quality by eliminating switching dead zone of HCI network and avoids short circuit fault from hardware level. According to one-cycle control (OCC), a novel nonlinear control strategy (termed as closed-loop OCC) is presented, which reduces the impact of dc inductor current ripple on input current. The principles of the improved swiss rectifier and closed-loop OCC are analyzed in detail, verified by simulation and on an 80 kHz, 300 V/2 kW prototype with digital controller. At rated condition, input current THD < 2%.

Power Management Using One Cycle Control Strategy for Triple Input Single Output Fly Back DC–DC Converter

Traditional multi-input converters have simpler configuration, but they have some disadvantages like multiple primary winding, high voltage stresses across the switches and also transfer of energy to the load occurs only from anyone of the input sources. This article proposes an isolated converter with reduced number of primary winding, and the load can be supplied by the sources either individually or simultaneously. The main objective of this work is to inject power into the grid using a three input single output Fly back DC–DC converter with closed loop control using one cycle controller (OCC) and PI controller. For power management, the inductor current is measured and the duty ratios of respective sources are controlled in such a manner that the average current flowing through the switch is proportional to power delivered by respective sources. In order to maintain the output voltage to be constant, the duty ratio of any one source is to be controlled by using outer voltage controller and inner current controller. Here, the duty ratios of first two sources are controlled by current mode control using OCC and the duty ratio of third source is controlled by using voltage controller with inner OCC current control. Since OCC is a nonlinear technique, only one PI controller is needed by the system. The system has only two sensors, one for measuring the output voltage and one for measuring the inductor current.

A Hybrid Islanding Detection Method for One Cycle Controlled PV Inverter System

Features like phase locked loop free implementation, simple-structure, grid voltage sensor-less operation, and its feedback response make one cycle control (OCC) inverters suitable and cost-effective for small single-phase photovoltaic distributed generator units. The feedback nature of OCC makes passive islanding detection more effective in comparison with other control methods. A novel hybrid islanding detection method (IDM), which is suitable for OCC inverters, is proposed in this article. The hybridization is done in two levels and is aimed at reducing the nondetection zone of the existing feedback-based passive IDM. The passive first level defense, which is always present, is due to the feedback nature of OCC. When islanding is suspected, the active second level defense is initiated by injecting a short real power disturbance. This accelerates the feedback action and helps in timely detection of islanding. Unlike other active methods, the disturbance is injected only when an islanding condition is suspected. The induced disturbance in real power is momentary, and the inverter goes back to the normal operation under nonislanded conditions. Simulation and experimental studies are performed to verify the effectiveness of the proposed IDM.

A Novel Improved Coordinate Rotated Algorithm for PWM Rectifier THD Reduction

In this paper, a novel algorithm with a rotating coordinate system is proposed to improve the total harmonic distortion (THD) of PWM rectifiers. Aiming at solving the disadvantages of poor dynamic response, unstable switching frequency, and a large calculation burden in some current control methods, the proposed method employs the rotating coordinate system to control the active current and reactive current separately while modifying the calculation error. The proposed method is verified through a single-phase PWM rectifier. Based on the measured results and compared with many other algorithms, such as the peak current mode control (PCMC), average current mode control (ACMC), one cycle control (OCC), and modulating duty ratio (MDR), the proposed method not only effectively reduces the intermediate variables during calculation, but also improves the THD and reliability of the circuit. The proposed method can be applied in single-phase PWM rectifiers applied in household-distributed energy storage systems.

Dynamical Analysis of Border Collision Bifurcation in One-Cycle Controlled Single-Inductor Dual-Output Boost DC-DC Converters

In this paper, the evolution of three types of border collision bifurcations are investigated thoroughly for a high-order single-inductor double-output DC-DC converter with one-cycle control (OCC). Multi-piecewise inductor current with more than one border and cross-coupling effect between different output ports are prominent features of the system, resulting in unexpected period incrementing cascade and transition from periodicity to chaos as a parameter is varied. A high-order nonlinear iterative map model is proposed, which reveals the underlying mechanisms of those complicated nonstandard and unsmooth bifurcations in the multiple-output system. Additionally, theoretical analysis shows that those nonstandard bifurcations arise from the boundary collisions, and more specifically, a fixed point suddenly appears in the borderline between various regions. Besides eigenvalue loci changes abruptly at the bifurcation point, the characteristic of border collision bifurcation is the topology sequence changes. Furthermore, the parameter boundaries are given to provide useful guidance for design. Finally, PSpice circuit experiments are performed to verify the above theoretical and numerical results.