Average Current Mode Control Research Articles

An approximate dynamic model of double-sided LCC resonant converter in wireless power transmission based on average current model

Wireless Power Transmission (WPT) system could realize a non-contact power transmission through the air gap weak magnetic coupling. This paper aims at analyzing a dynamic model of the WPT system based on a double-side LCC. Firstly, in the multivariable framework, the dynamic characteristics of double-side LCC resonant compensation topology are analyzed by the mutual inductance model. The approximate small-signal model of double-side LCC resonant converter is derived by generalized state-space averaging (GSSA). Additionally, a double-side LCC compensation topology based on double closed-loop average current mode control approach is proposed. By contrasting the behavior of the WPT system under various operating conditions, the efficacy of the suggested dynamic model is illustrated. Finally, a wireless power transmission system experiment platform with a resonant frequency of 85 kHz and an output power of 3 kW was built. Through the experiments, it is determined that the model has a certain ability to predict the dynamic behavior of the wireless charging system. So, it can be utilized as a useful instrument for the transient's analysis and the controller development optimization.© 2017 Elsevier Inc. All rights reserved.

A Control Circuit Small Wind Turbines with Low Harmonic Distortion and Improved Power Factor

This paper presents the application of average current mode control to reduce the THDi and increase the PF in a Three-Phase Boost Rectifier driving a small wind turbine. It is used as input stage of small wind turbines with permanent magnet synchronous generators operating at variable speed. The Boost Rectifier´s output is connected to an inverter which feeds the energy to a distribution power grid. The operation in discontinuous conduction mode allows significantly reducing the Total Harmonic Distortion of the current in the small wind turbine. However, it is necessary to add an input filter so that the switching ripple doesn´t arrive to the small wind turbine. It is evaluated the convenience of the current sensors placement in the DC side of the rectifier or at the output of the generator. The results demonstrate that it is better to place the sensors in the output of the generator, because it is achieved smaller THDi and higher PF.

Average current mode controller for bridgeless PFC SEPIC converter with second-order model reduction operated in continuous conduction mode.

This paper proposes an average current mode controller (ACMC) for a single-phase bridgeless power factor correction (PFC) circuit using a single ended primary inductor converter (SEPIC) via second-order model reduction. The superiority of the proposed controller is PFC accomplished at power up to 350 W with high efficiency via the second-order model reduction. The design and implementation of ACMC on the converter operated with continuous conduction mode (CCM) is explained in detail. ACMC forces input current to follow sinusoidal current reference at different power levels and sustain high power factor (PF). The proposed controller is designed based on the theoretical analysis operation of the circuit. For verification, MATLAB/Simulink simulations are carried out and validation through an experiment test rig for 110-220 Vrms input, 100 Vdc/ 350 W output prototype at 20 kHz switching frequency. It is proven that the proposed controller strategy accomplishes high PF, high efficiency and conformity with the simulation.

A Discrete Average Current Mode Control CCM Boost PFC Converter With Hybrid Pulse Train Modulation and Dual Edge Modulation

In this paper, a discrete average current mode (ACM) control method with hybrid modulation, which is composed of pulse train modulation (PTM) and dual edge modulation (DEM), is proposed for boost power factor correction (PFC) converters operating in continuous conduction mode (CCM) to achieve both fast dynamic response and high power factor (PF). The proposed discrete ACM control is special in that fast and accurate control are achieved by directly generating discrete duty cycles to fit a unity PF duty cycle. The target duty cycle consists of two components <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">d</i> <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">1</sub> ( <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">t</i> <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">n</sub> ) and <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">d</i> <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> ( <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">t</i> <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">n</sub> ) related to output voltage and inductor current respectively. Based on <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">d</i> <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">1</sub> ( <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">t</i> <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">n</sub> ), the voltage control loop adjusts the output voltage by applying PTM in every half-line cycle. And based on <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">d</i> <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> ( <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">t</i> <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">n</sub> ), the current control loop, which is independence from the voltage control loop, regulates the inductor current to track reference current in every switching cycle to achieve high PF. Therefore, the voltage and current control loops of the proposed control are decoupled. The control principle, parameters design and control performances of the proposed discrete ACM control method are developed. Experimental results of 320-W prototype are presented to validate the proposed control method.

A non-inverting single-switch buck-boost converter based LED driver

&lt;span lang="EN-US"&gt;This paper focuses on a single-switch buck-boost (SSBB) converter for light emitting diode (LED) lighting applications. The proposed LED driver with power factor correction (PFC) shows enhanced performance in terms of input power factor, efficiency and reduced voltage stress across the switch. The presented LED driver is operated in discontinuous conduction mode (DCM). The input PFC is carried out using average current mode control (ACMC) and the controller is optimized using artificial bee colony (ABC) algorithm. A hardware prototype of 50W LED driver with ACMC for PFC is implemented using a programmable interface circuit (PIC) microcontroller. The experimental results are presented and the performance is compared with a conventional buck boost LED driver. The proposed SSBB LED driver achieves an input power factor of 0.96 with an efficiency of 98%.&lt;/span&gt;

Virtual Admittance Feedforward Compensation and Phase Correction for Average-Current-Mode-Controlled Totem-Pole PFC Converters

This paper explores a current distortion problem in totem-pole bridgeless power factor correction (PFC) converters with average current mode (ACM) control. With in-depth modeling for the current and voltage loops, it was found that the current distortion is caused by the limited current loop bandwidth and input filter capacitor. These factors lead to the presence of a susceptance component in the input admittance, which degrades the power factor (PF) and total harmonic distortion (THD) of the PFC converter. To solve this problem, this paper proposes virtual admittance feedforward compensation (VAFC) and phase correction methods to adjust the input admittance to pure conductance. The VAFC can generate virtual admittance that compensates for susceptance components in the input admittance, while phase correction can generate an equivalent current source that offsets the current in input capacitors. Furthermore, a phase lock loop (PLL) is introduced to realize the VAFC, which reduces the feedforward interference caused by input voltage sampling noise. Finally, an experimental prototype was built to verify the effectiveness of the proposed strategies. According to the test results, the proposed compensation strategy improves the PF by 1.23%, while reducing the THD by 2.52% and achieving a peak efficiency of 98.69%.

Fractional fuzzy PI controller using particle swarm optimization to improve power factor by boost converter

The power circuit of AC voltage controller capable of operating at a leading, lagging, and unity power factor is studied by a lot of researchers in the literature. Circuits working with high switching frequency are known as power factor correctors (PFCs). The single-phase boost converter has become the most popular topology for power factor correction (PFC) in general purpose power supplies. Power factor correction circuit provides conventional benefits to electric power systems. The benefits are the reduction of power factor penalty and utility bill and power loss. Therefore, a boost converter power factor correction scheme is presented in this paper. A PI, fuzzy logic PI and fractional order PI (FOPI) controllers are used to fix an active shaping of input current of the circuit and to improve the power factor. The controller parameters (coefficients) are optimized using the Particle Swarm Optimization (PSO) algorithm. Average current mode control (ACMC) method is used in the circuit. The converter circuit consists of a single-phase bridge rectifier, boost converter, transformer and load. A mathematical model of the plant is required to design the PI controller. A model for power factor correction circuit is formed in MATLAB/Simulink toolbox and a filter is designed to reduce THD value. The proposed model is simulated using a combination of PI, fuzzy logic and FOPI controllers. The control scheme is applied to 600 Watt PFC boost converter to get 400 Volt DC output voltage and 0.99 power factor. The input voltage is 230 VRMS with 50 Hz. The combination of FOPI and PI controller has the best solution to control the power factor according to PI and fuzzy controllers.

Photovoltaic Systems Based on Average Current Mode Control: Dynamical Analysis and Chaos Suppression by Using a Non-Adaptive Feedback Outer Loop Controller

This paper deals with the modeling and theoretical study of an average-current-mode-controlled photovoltaic power conversion chain. It should be noted that current mode control is a superior scheme for controlling DC–DC power electronic converters for photovoltaic applications. Bifurcation diagrams, largest Lyapunov exponents, Floquet theory, and time series are used to study the dynamics of the system. The theoretical results show the existence of subharmonic oscillations and period-1 oscillations in the system. The results of the numerical simulations showed that when the battery voltage at the output of the converter is fixed and ramp amplitude is taken as a control parameter, the photovoltaic power system exhibits the phenomenon of period doubling leading to chaotic dynamics. Furthermore, bifurcation diagrams showed that both the critical value of ramp amplitude for the occurrence of border collision bifurcation and the critical value of ramp amplitude for the occurrence of period-1 in the proposed system increased with the value of the battery terminal voltage. The numerical results are in accordance with the theoretical ones. Finally, an external control based on a non-adaptive controller having a sinusoidal function as a target is applied to the overall system for the suppression of chaotic behavior.

Performance Improvement by Sampling Position Approach in Dual Loop Digital ACM Controlled DC-DC Boost Converter

In DC-DC boost converter mostly discontinuous voltage ripple is associated with Equivalent Series Resistance (ESR) of the output side capacitor. This voltage ripple makes the design of digital controllers challenging in deciding the appropriate sampling position in one switching period. The necessity of Right Half Plane Zero (RHPZ) elimination, which impacts the stability is managed by shifting the sampling position to OFF-time duration. This is mostly analyzed in the frequency domain. The proposed work provides the time-domain analysis in consideration of ESR impacting the RHPZ. A dual loop Digital Average Current Mode (DACM) controller which has two sampling position freedom is considered in this brief. The ESR value of the output capacitor for extracting the benefits of RHPZ elimination is proposed with help of the discrete-time modeling technique. An analytical discussion about the influence of RHPZ elimination with time-domain characteristics such as, voltage deviation, peak-to-peak inductor current oscillations, and efficiency is presented. Finally, two 60W boost converters prototype with different output capacitor (C) and its ESR <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$(r_{C})$ </tex-math></inline-formula> values are developed to validate the proposed analysis.

Design, modelling, and simulation of bridgeless SEPIC-fed three-level soft switched converter for EV battery charging

ABSTRACT This paper discusses the design and analysis of a three-level LLC (TL-LLC) resonant converter for an electric vehicle (EV) charging application. The proposed two-stage onboard charger comprises an ac-to-dc power factor correction (PFC) stage, followed by the second stage required to provide galvanic isolation and dc-to-dc conversion. The PFC stage uses a bridgeless SEPIC converter with average current control and voltage mode control algorithm for achieving unity power factor (pf) operation with constant DC link voltage. In contrast, the dc/dc stage uses a three-level LLC resonant converter with a frequency control algorithm to control the output voltage. A 1 kW, 360 V output model of the proposed onboard charger is implemented and simulated in PSIM, and the obtained results are investigated and examined in detail. Results obtained from the simulation show a power factor greater than 0.99 with THD less than 5 % at the input side. For TL-LLC, both zero voltage switching (ZVS) for primary MOSFETs and zero current switching (ZCS) for secondary side rectifier diodes are achieved.

Design, implementation and performance evaluation of different digital control techniques for current controlled DC-DC Buck converter

The paper presents modelling, control architecture, analysis and design of digital compensators for single feedback-loop voltage mode control as well as two feedback-loop average current mode control and peak current mode control of current controlled DC-DC Buck converter operating in continuous conduction mode with output current as control variable. The compensators are derived using digital redesign approach, simulated on MATLAB, implemented as control algorithms on Texas Instruments' 32-bit TMS320F28069M microcontroller platform, and experimentally validated by testing with a laboratory prototype of current controlled Buck converter. Simulation and experimental results are discussed, compared and evaluated for converter output current performance in tracking reference current signal as well as in regulation against input voltage and load disturbances. Salient features of each control technique are identified and described to determine its suitability in applications of DC-DC converters requiring controlled output current.

Average Current Mode Control of a DC–DC Boost Converter to Reduce the Decoupling Capacitance at the PV Array Output

Due to the full-wave AC–DC power conversion, second-order frequency oscillations of current and voltage are created in single-phase PV-grid-connected inverters. These oscillations propagate toward the input and adversely affect the PV power utilization ratio. Large power decoupling capacitors are the preliminary solution for coping with voltage ripples across PVs, and they decrease the lifetime of the overall system. This paper proposes the average current mode control (ACMC) of the input inductor in a DC–DC boost converter in a double-stage PV power conversion system. Through extensive explanations of the modeling and control of a DC–DC boost converter, it is shown that the ACMC reduces the propagation of the second-order frequency components (SOFCs) toward the input PV array. Two controllers—a proportional–integral controller and an integral single-lead controller—are considered to adjust the average value of the PV output current in a single-loop control structure. This control approach is simple to implement and exhibits high impedance to current oscillatory components, which, in turn, reduces the size of the required capacitance.

Improved dynamic performance with discrete sampling in digital ACM controlled DC‐DC boost converter with capacitor ESR inclusion

AbstractA classical symmetrical carrier‐based digital Average Current Mode (ACM) control has two sampling choices, peak point and valley point, to control the average inductor current. If it is employed to regulate the DC‐DC boost converter, there will be a difference in the dynamic performance at peak and valley point sampling instants because of discontinuous output voltage ripple due to Equivalent Series Resistance (ESR) of the output capacitor. Therefore, this paper investigates the effect of sampling instant on the dynamic performance of the PWM DC‐DC boost converter in consideration of capacitor ESR. The small‐signal transfer functions of a boost converter for both sampling positions are prominent to analyze each sampling impact on its dynamics. They are derived by using discrete‐time modeling. Further, the choices of sampling instant are investigated related to the RHP zero elimination, voltage stability, and peak‐to‐peak ripple current of the DC‐DC boost converter. The boost converter has improved stability performance by synchronizing the ADC sampling at starting position (valley point) of the symmetrical carrier signal, as evident by the analytical and hardware results of both sampling techniques working from 25% to 100% load working conditions.

Design of an Integrated, Six-Phase, Interleaved, Synchronous DC/DC Boost Converter on a Fuel-Cell-Powered Sport Catamaran

This paper describes the preliminary analysis, design and implementation phases of a DC/DC boost converter dedicated to the Futura catamaran propulsion chain developed by the UniBoAT team at the University of Bologna. The main goal of the project was the reduction of the converter’s weight by eliminating the use of heat sinks and by reducing the component size, especially inductors and capacitors. The obtained converter is directly integrated into the structure containing the fuel-cell stack. The realized converter was based on an interleaved architecture with six phases controlled through the average current mode control. The design was validated through simulations carried out using the LT-Spice software, whereas experimental validations were performed by means of both bench tests and on-field tests. Detailed thermal and efficiency analyses were provided with the bench tests under the two synchronous and non-synchronous operating modes and with the adoption of the phase-shedding technique. Prototype implementation and performance in real operating conditions are discussed in relation to on-field tests. The designed converter can be used in other applications requiring a voltage-controlled boost converter.

Guest Editorial Special Issue on Power Electronics Systems for Aerospace Applications

Aerospace applications have been a major driver for the development of power electronics. The demand of light and efficient power supplies, common both for space and aeronautic applications, spearheaded the research and development efforts around switching mode power systems. Major seminal works in the field, such as those pioneered by Prof. R. D. Middlebrook, were developed under funding from National Aeronautics and Space Administration (NASA). Another example is that average current mode control or transconductance control was developed in the European Space Agency (ESA) laboratories while at the same time peak current mode control was invented in U.S. institutions.

Performance Analysis and Improvement of PI-Type Current Controller in Digital Average Current Mode Controlled Three-Phase Six-Switch Boost PFC Rectifier

In this article, the performance of the proportional–integral-type (PI-type) current controller in the digital average current mode (ACM) controlled three-phase six-switch (3ph-6s) boost PFC rectifier is analyzed with the consideration of the effect of the dead time, the time delays, and the dc offsets of the sampled input voltages/currents. Current control model is established to analyze the effect of the time delays and the dead time on the inductor currents. Analysis results show that both the time delays and the dead time lead to the phase shift of the inductor currents. The design principle of the current controller to suppress the negative effects of the time delays and the dead time on the phase of the inductor currents is given, and the PI-type current controller is found to considerably restrain the negative effects of the time delays and the dead time. However, in the traditional ACM control scheme with the PI-type current controller, the dc offsets of the sampled input voltages/currents lead to serious inductor current distortion. The current distortion is discussed, and the average line current control scheme is proposed to eliminate it. The analysis results are verified by simulation and experimental results of a 4-kW prototype.

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.

A High-Frequency Dynamically Coordinated Hybrid Si/SiC Interleaved CCM Totem-Pole Bridgeless PFC Converter

A high-frequency dynamically coordinated Si/SiC hybrid continuous conduction mode (CCM) totem-pole bridgeless PFC (TPBPFC) converter is reported in this article. The proposed hybrid TPBPFC converter is interleaved with a low-current high-frequency SiC phase and a high-current low-frequency Si phase, in comparison to the prior-art design of two half-capacity SiC phases, resulting in a considerable cost reduction. A coordinated Si/SiC control strategy is proposed to address the un-compensable range issue in hybrid-frequency interleaving topologies, and to dynamically distribute power load between the Si and SiC phases for optimal efficiency and performance. An average current mode control (ACMC) based control algorithms and sequences are discussed in detail to enable the unique operation. A 3.3-kW hybrid TPBPFC prototype made of Si IGBTs and SiC MOSFETs is built and tested to validate the proposed design concept. Compared to the prior art two-phase all-SiC interleaved TPBPFC design, the proposed hybrid TPBPFC has demonstrated nearly identical power efficiency, THD, power factor, and effective frequency, while offering 33.5% device cost and 15.1% total cost reductions.

Online Broadband Battery Impedance Spectroscopy Using Current-Mode Boost Converter

In this paper an online method of broadband battery impedance spectroscopy is proposed in which the excitation signal is injected through the inner feedback loop of a DC/DC boost converter with average current-mode control (ACMC). By deriving the average state-space model of the conventional boost converter, it is shown that an open-loop converter exhibits a resonant frequency response in regards to the injected signal, whereas the compensated current loop in ACMC produces a controllable, flat-gain closed-loop transfer function that allows broadband current excitation signals to be injected into the battery without the distortion that is seen in the open-loop configuration. In the presented method, the converter is set to discharge the battery at a constant C-rate during impedance measurement while a broadband signal is superimposed onto the loop reference current. A low-dropout regulator is then used to filter out disturbances caused in the converter output. The proposed approach is experimentally implemented and a discrete-interval binary sequence signal is utilized to measure the impedance of two 18650 lithium-ion batteries in several arbitrary frequencies at once in the 0.1Hz-1kHz range. The measured spectra are validated by a commercial impedance analyzer.

Implementation and Optimization of Two Degree of Freedom H∞ Loop Shaping Control for Average Current Mode Control Buck Converter using Genetic Algorithm

Implementation and Optimization of Two Degree of Freedom H∞ Loop Shaping Control for Average Current Mode Control Buck Converter using Genetic Algorithm