Power Factor Correction Rectifier Research Articles

Modeling and Experimental Validation of Broad Input-Output Range Three-Voltage-Level Rectifier

A new type of single–conversion–step wide–input–range versatile step–up/down three–voltage–level power–factor correction stage is presented in this manuscript. The rectifier can operate both in continuous–conduction mode and discontinuous–conduction mode. First, the rectifier’s principle of operation is described, and then the innovative rectifier is analyzed in continuous and discontinuous–conduction modes. After, an average model for the innovative rectifier is developed. Lastly, the proposed theory is experimentally validated using a multiplier–less dual–control–loop mode at discontinuous–conduction modes. It is shown that although no multiplier is used in the control circuitry, the power factor is near unity. It is revealed that the rectifier can swing the output voltage from 50 V to 900 V while the input voltage is 230 Vrms. Although the rectifier output has a split DC bus with three voltage levels, the required control effort is low, and the output voltage is balanced. The innovative topology suits any standard power–factor correction rectifier application, dual–stage low–voltage power supply, and three–level voltage supplement for low–harmonic inverters. Since the rectifier’s output–voltage swing is extremely wide, energy storage systems and electric vehicle batteries are suitable applications.

SWISS rectifier structure sector boundary current distortion suppression based on multi‐step predictive control

AbstractThe SWISS rectifier is a three‐phase BUCK type Power Factor Correction rectifier with the advantages of adjustable output full voltage range, low voltage stress in the back stage devices, and high efficiency. However, because the voltage ripple of the input filter capacitor will cause the input current deviation, the input current of the SWISS rectifier will produce distortion at the sector boundary, which will affect the system performance. To this end, a multi‐stage predictive model method based on the spherical algorithm is presented. By predicting the grid‐side capacitor voltage and the input current state of the rectifier, the harmonic injection network switching tube is controlled in advance to supplement the grid‐side capacitor voltage, so that the grid‐side capacitor voltage approximately tracks the input voltage. Meanwhile, considering the current step that may be generated after the current distortion returns to normal, which leads to the resonance problem with the pre‐stage filter, this problem is incorporated into the value function and damping is optimized according to the feedback value. Finally, a 10‐kW SWISS rectifier on the SIMULINK platform is used to verify the feasibility of the new control method.

A 5-kW unidirectional wireless power transfer EV charger with a novel multi-level PFC boost converter on front-end side

The greatest advantages of wireless power transfer (WPT) are its absence of severe environmental hazards, its portability, and its independence from other factors. The wireless charging system for electric vehicles has a serious problem with the amount of misalignment it can tolerate. This study explores the usage of a novel multi-level boost power factor correction (PFC) rectifier with less switch count to improve the efficiency of power conversion of a 5-kW wireless electric vehicle (EV) charger. Especially in the context of wireless charging, which provides convenience and flexibility, there is a pressing need for efficient and dependable charging infrastructure to keep up with the rising demand for electric vehicles. In contrast to wired EV chargers, wireless chargers often have poorer power conversion efficiency because of losses in power semiconductor devices. An innovative multi-level boost PFC rectifier design is offered as a solution to this problem since it uses fewer switches while retaining high-performance levels. The suggested rectifier achieves much higher power conversion efficiency. In addition, power factor correction capabilities are improved, making it comply with global rules. Simpler, cheaper, and more dependable rectifiers improve the whole system.

New single‐stage bidirectional three‐phase ac‐dc solid‐state transformer

AbstractHigh‐power applications with low‐voltage (LV) dc loads, for example, fast charging stations for electric vehicles (EVs), are typically supplied from the medium‐voltage (MV) grid. Aiming for low volume, MVac‐LVdc solid‐state transformers (SSTs) that provide galvanic separation with medium‐frequency transformers (MFTs) are thus considered, which are conventionally realized as two‐stage systems that consist of an ac‐dc power‐factor‐correction (PFC) rectifier and an isolated dc‐dc converter. This letter extends a new single‐stage isolated bidirectional PFC rectifier concept to MV levels, resulting in an SST that performs MVac‐LVdc conversion in a single converter stage and, unlike many modular SST concepts, employs only a single MFT. The SST's primary side operates modular‐multilevel‐converter (MMC) bridge legs, whose input voltages contain large ac components, in the quasi‐two‐level mode to minimize the cell capacitors. The secondary side employs a standard LV three‐phase rectifier, and a dual‐active‐bridge‐(DAB)‐like modulation strategy allows power flow regulation and ensures sinusoidal grid currents. The concept is explained and validated using detailed circuit simulations of an exemplary 1‐MW system operating between a 10‐kV three‐phase grid and an 800‐V dc output. The component stresses are evaluated, and an efficiency of 98.1% and a power density of up to 0.6 kW/dm3 are estimated.

Reduction in the Number of Current Sensors of a Semi-Bridgeless PFC Rectifier Based on GaNFET Characteristics

The semi-bridgeless power factor correction (PFC) rectifier is widely used due to its high power factor, high efficiency, and low electromagnetic interference. However, in this rectifier, the inductor current will flow through the body diode of the metal–oxide–semiconductor field-effect transistor (MOSFET) when the MOSFET does not work, causing a problem in detecting the inductor current. Consequently, the current transformers are generally used as current sensors. This means that using many current sensors will make the cost and the peripheral detection circuit complicated. In this paper, our new method is to use a gallium nitride field-effect transistor (GaNFET) to replace the metal–oxide–semiconductor field-effect transistor (MOSFET) in the main switch selection. The reverse-biased conduction voltage of the third quadrant of the GaNFET is higher than the forward-biased conduction voltage of the diode, which solves the problem in detecting the inductor current, reduces the number of current sensors, and simplifies the corresponding peripheral circuits and components. Eventually, via mathematical deduction and hardware implementation, a semi-bridgeless PFC prototype with a GaNFET was built to verify the effectiveness of the proposed structure.

Model Predictive Control of a PUC5-Based Dual-Output Electric Vehicle Battery Charger

In this study, a model predictive control (MPC) technique is applied to a packed-u-cell (PUC)-based dual-output bidirectional electric vehicle (EV) battery charger. The investigated topology is a 5-level PUC-based power factor correction (PFC) rectifier allowing the generation of two levels of DC output voltages. The optimization of the MPC cost function is performed by reducing the errors on the capacitors’ voltages (DC output voltages) and the grid (input) current. Moreover, the desired capacitors’ voltages and peak value of the input current are considered within the designed cost function to normalize the errors. In addition, an external PI controller is used to generate the amplitude of the grid current reference based on the computed errors on the capacitors’ voltages. The presented simulation and experimental results recorded using a 1 kW laboratory prototype demonstrate the high performance of the proposed approach in rectifying the AC source at different levels (dual rectifier), while drawing a sinusoidal current from the grid with low THD (around 4%) and ensuring a unity power factor operation.

Extension of OCC Controller for High-Voltage-Gain PFC Applications

Single-stage single-switch power factor correction (PFC) rectifiers for high output voltage applications are investigated. Considerations for selecting a power stage for high-gain PFC are suggested and discussed. Accordingly, several candidate topologies for high-step-up DC/DC converters are identified and overviewed. A modified PFC OCC control scheme with extended capabilities is suggested to control the proposed high step-up PFC rectifiers. The proposed controller provides a simple and low-cost solution that can accommodate a wide range of rectifiers. Theoretical analysis is supported by simulation and experiments.

A single‐stage bridgeless isolated positive output Cuk configuration‐based unidirectional onboard battery charger

SummaryAs power factor correction rectifiers play a key component of electric vehicle (EV) battery charger, the advancements in designing of improved power quality‐based EV charger become more significant in modern era. This article exposes a single‐stage bridgeless isolated positive output (BIPO) Cuk PFC converter with a noninverted output signal. The input diode rectifier present at the input is redeemed by the bridgeless topology that eliminates the serious power quality (PQ) issues and proffers the eminent charging solution for the light electric vehicles (LEV). Unlike the conventional Cuk converter, the noninverted outcome of the BIPO converter does not require a separate amplifier for converting negative to positive output voltage. The preferred charger utilizes a single voltage and current sensor to synchronize the battery charging control in the constant current (CC) and constant voltage (CV) phases of charging. Therefore, the converter encompasses intrinsic zero current switching (ZCS) and offers low‐cost solution to the charger with reduced control complexities. The extensive state space approach is executed to analyze the marginal stability of the presented system. Moreover, the detailed loss modeling is addressed to show the charger's efficacy curve at the standard conditions. A hardware prototype of 350 W, 60 V/4 A charger is implemented to validate its steady‐state and dynamic performance.

A quasi‐two‐switch power factor correction converter for on‐board battery chargers

SummaryThis paper describes a quasi‐two‐switch buck‐boost power factor correction (PFC) converter for use in on‐board battery chargers to create a variable output voltage that is less than or greater than the peak input voltage. A two‐stage converter links the input grid power to the battery pack both in battery‐operated electric cars (BEVs) and plug‐in hybrid electric vehicles (PHEVs), with battery pack voltages ranging from 100 to 500 V depending on vehicle size and capacity. A universal charger that can manage such a wide range of battery pack voltages is appropriate for all vehicle designs. This requirement is met by supplying a changeable DC link voltage at the input of the DC/DC converter, which is a major obstacle in battery chargers when it comes to achieving universal output voltages. The major contribution of this research is the analysis and design of a dual‐control technique for a cascaded buck‐boost converter suited for a power factor correction (PFC) rectifier. The control loop is designed to allow a seamless transition from buck‐boost operation while putting less stress on the devices. The converter's power loss and small‐signal model are also investigated. From an economic standpoint, this concept allows the automobile industry to manufacture a single power converter, which is flexible and capable of charging numerous vehicle variants. Results have been verified both with a PSIM (11.0) simulation model and an experimental setup for a 1‐kW PFC converter suitable for universal input voltages of 85–265 Vrms and broad output voltages.

SR Control With Zero Current Detection Delay Compensation for GaN CRM Totem-Pole PFC Rectifier

An SR control with ZCD delay compensation is proposed to reduce the high reverse inductor current and input current distortion caused by the zero current detection (ZCD) delay in critical mode totem-pole power factor correction (PFC). The basic idea of the proposed control is to calculate the SR turn-off instant considering the ZCD delay. Accurate operation model in VOT control is analyzed with ZCD delay compensation to realize the proposed control. A prototype of 2 kW GaN CRM totem-pole PFC converter is built to verify the proposed control. The total harmonic distortion (THD) with full load decreases to 3% by mitigating the current distortion caused by the ZCD delay, 1.6% lower than that before compensation. The high reverse inductor current near the zero-crossing of input voltage is avoided since the length of the zero-current platform is shortened by 87.5%. The prototype achieves 99% efficiency at full load (2 kW) and a power density of 120 W/inch <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sup> .

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.

Burst Mode Control of Active-Power-Decoupling Integrated Active Clamp Flyback PFC Rectifiers

To mitigate the bulky and heavy twice-line frequency power buffer in single-phase power-factor-correction (PFC) rectifiers while maintaining a lower cost, active-power-decoupling integrated active clamp flyback (iACF) PFC rectifier is recently proposed in the literature. The solution inherits all the benefits of conventional ACF converters such as low component count, leakage energy recycling, and soft-switching while being able to reduce the size of the power buffer in the system without hardware modifications. However, existing modulation and control strategies, based on Continuous-Conduction-Mode (CCM), can only achieve a high efficiency at heavy load but not at light load. This paper proposes a new modulation to improve the light-load efficiency of iACF PFC rectifiers. By combining CCM and burst mode of operation, this new modulation method can maintain all good features of CCM while effectively reducing the operating frequency, thus reducing the switching losses of the system at light load. This paper firstly reviews the existing light-load modulation methods for ACF converters and limitations of applying these methods to iACF are highlighted. The detailed operating principles of the proposed modulation method are explained, and controller implementation that supports simultaneous full-load, medium load and ultra-light load operation is developed. A 100-W laboratory iACF prototype is developed to verify the feasibility of the proposal, showcasing a 4-point average efficiency 91.9%, superior to the conventional two-stage solutions.

A Novel Single/Multiple Output Multilevel Buck Rectifier for EV-Battery Charging

An electric vehicle (EV) charging system is usually implemented in two stages: a power factor correction (PFC) rectifier stage, followed by a DC-DC converter. For such power conversion, multilevel rectifiers (MLRs) offer advantages compared to a two-level rectifier, such as reducing voltage ratings of power switches and yielding high-quality input voltage waveform. In MLRs, one of the most challenging aspects is balancing the capacitors’ voltages. This article proposes a self-balancing five-level PFC rectifier with the possibility of single/multiple outputs. The proposed rectifier performs buck operation and offers a wide output voltage regulation, which is suitable for EV battery charging. The five-level operation of proposed buck rectifier with continuous conduction mode (CCM) leads to elimination of the inductive filter on the DC side and the capacitive filter on the AC side. This article presents the operating principle, modulation strategy, closed-loop control and experimental validation of the proposed topology.

A Topology-Reconfigurable Fault-Tolerant Two-and-Single Stage AC–DC Converter for High Reliability Applications

A novel topology-reconfigurable two-and- single stage ac–dc converter with fault-tolerant capability for high reliability applications is proposed in this article. In the proposed converter, two bidirectional switches are used to connect the midpoints of the bridge branches between the rectifier stage and the dc–dc stage, and the proposed converter can be configured from the two-stage structure into the single-stage structure by turning on the bidirectional switches for the postfault conditions, therefore, the reliability of the power supply is reinforced. The two-stage structure for the normal condition works with an interleaved bridgeless power factor correction (PFC) rectifier and resonant dc–dc converter. The single-stage structure working under the postfault condition is made up of a PFC half-stage and resonant dc–dc half-stage, and the single-stage structure still has the same working performance as the two-stage structure. Operational principles, control scheme, and characteristics analysis of the topology-reconfigurable converter are analyzed. Finally, experimental results for both normal condition and postfault condition based on 1 kW prototype are provided to verify the effectiveness of the proposed converter.

High-Efficiency Interleaved Totem-Pole PFC Converter With Voltage Follower Characteristics

High power density, efficiency, control simplification, and robustness are highly demanded for power factor correction (PFC) converters. This paper proposes a totem-pole rectifier based on the switching cell with switching frequency modulation (SC-SFM). The SC-SFM features interleaved operation, soft commutation, and resistive characteristics with continuous conduction in the input inductor. The converter operates without needing sensors and a control loop for the current. Unlike conventional solutions or some sensorless converters, the converter does not require a fast control loop to shape the current since the current naturally follows the input voltage. Only one output voltage sensor and one input half-line cycle detector are required to achieve unitary power factor and regulated DC output voltage. A detailed analysis of the converter operation, including the operating principle, mathematical analysis, a small signal model, and control method, is presented, including the differences in operation from the conventional PFC rectifier with the diode bridge. Experimental results evaluate a 1-kW prototype with different switch technologies (IGBT, SiC, and GaN).

Third-Harmonic-Type Modulation Minimizing the DC-Link Energy Storage Requirement of Isolated Phase-Modular Three-Phase PFC Rectifier Systems

A three-phase ac/dc converter with high-frequency isolation can be realized as a monolithic three-phase or as a phase-modular system by combining three single-phase Power Factor Correction (PFC) rectifier modules with individual isolated dc-dc converters. Advantageously, for a phase-modular system the module configuration can be changed depending on the instantaneous input-output voltage ratio (i.e., a star-(Y)- or a delta-(Δ)-arrangement such that wide voltage ranges can be covered without a massive over-dimensioning of the main power components. However, the main disadvantage of a phase-modular converter realization is the fact that the input power of each PFC rectifier module pulsates at twice the mains frequency (which is inherent to single-phase power conversion) such that large dc-link capacitors are required. Recent literature predicts a substantial power pulsation reduction enabled by means of third-(3 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">rd</sup> )-harmonic injection modulation which is applicable for the Y-connection (where a common-mode (CM) / zero-sequence (ZS) voltage is injected), and for the Δ-connection of the three single-phase PFC rectifier modules (where a CM / ZS current is injected). This changes the distribution of the power flow in the three-phase system and the power pulsation is shifted to higher frequencies. This paper experimentally verifies and extends the dc-link energy storage requirement reduction of the 3 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">rd</sup> -harmonic injection modulation concept: In a first step, the derivation of the harmonic injection concept is recapitulated and suitable control methods are discussed for both CM voltage (Y-arrangement) and CM current (Δ-arrangement) injection. Further, an alternative CM voltage injection strategy with simplified reference generation based only on the instantaneous grid voltage measurements is presented and compared to the pure 3 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">rd</sup> -harmonic injection modulation. Measurement results obtained from a 6 kW prototype reveal a dc-link voltage variation and/or energy buffering reduction by up to 38.6 % enabled by the harmonic injection modulation compared to conventional operation without 3 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">rd</sup> -harmonic injection modulation.

Single-Phase Hybrid Switched-Capacitor PFC Boost Rectifier With Low Voltage Gain

Power factor correction (PFC) rectifiers based on the classic boost topology have become widespread owing to their current input features, and can obtain optimal results in terms of power quality. However, several applications require an output dc voltage lower than the ac input voltage. In such cases, two-stage topologies provide lower voltage values at the output, which increases the number of components. Moreover, such topologies tend to incur higher losses and are costly. Therefore, a unidirectional hybrid single-stage single-phase PFC boost rectifier with a switched-capacitor cell and low voltage gain is proposed. Furthermore, the proposed topology has two active switches, and natural balance exists between the voltages of the capacitors. Therefore, an additional control system is not required. The proposed topology was theoretically analyzed and experimentally validated using a 1 kW prototype with two different operational situations: (A) 127 V ac and 100 Vdc; (B) 220 Vac and 200 Vdc, input and output voltages, respectively. The experimental results essentially reveal that the power factor is approximately one, and the total harmonic distortion of the input current is 4.6%. The maximum efficiency achieved was 96.5% in the operational situation (B).

DC-Link Capacitance Reduction in PFC Rectifiers Employing PI+Notch Voltage Controllers

It is well-known that adding a notch filter in series with the typically employed type-II (or PI) regulator allows improving the tradeoff between dc-link voltage dynamics and grid-side current total harmonic distortion (THD) in practical single-phase power factor correction rectifiers. The article demonstrates that notch filter utilization alternatively allows reducing the value of dc-link capacitance in case hold-up time requirement is absent. The revealed value of minimum capacitance is expressed by explicit function of possible mains frequency values range, maximum expected grid voltage magnitude, rated system power, dc-link voltage set point, maximum tolerable grid-side current THD, and the desired phase margin (PM) of dc-link voltage loop. It is demonstrated that the proposed approach yields fourfold reduction of dc-link capacitance for typical values of 5% tolerable grid-side current THD under 40° PM constraint. Experimental results exhibit close-fitting resemblance to corresponding analytical predictions, verifying the proposed methodology.

Selection of PI + Notch Voltage Controller Coefficients to Attain Desired Steady-State and Transient Performance in PFC Rectifiers

The well-known trade-off between dc link voltage dynamics and ac-side current quality in power factor correction (PFC) rectifiers limits attainable dc link voltage loop bandwidth. It has been shown that adding a notch filter in series with the typically employed PI or type-II regulator allows improving dc link voltage dynamics without sacrificing total harmonic distortion (THD). However, clear quantitative guidelines for PI + Notch (PI + N) controller design to attain prescribed values of ac-side current THD and dc link voltage undershoot (response to a step-like load power increase) were not established so far. Consequently, analytical expressions linking the coefficients of the PI + N controller with the above-mentioned performance merits for a given value of dc link capacitance are revealed in this article. Corresponding dc link voltage loop gain phase margin and crossover frequency expressions are derived and the feasibility region of the proposed design guidelines is clearly indicated. Simulations and experimental results validate the proposed design methodology.

Independent Current Control With Differential Feedforward for Three-Phase Boost PFC Rectifier in Wide AC Input Frequency Application

Independent current control of the three-phase boost power factor correction (PFC) rectifier with differential feedforward is proposed for wide ac input frequency application. When conventional independent current control with proportional controller (P-controller) is used for digital-controlled three-phase boost PFC rectifier, the time delay of digital control brings phase leading of input currents. Such a phase leading is proportional to the ac input frequency. To achieve high power factor in wide ac input frequency application, differential feedforward is introduced to the input current control in the proposed control strategy to suppress the phase leading of input currents. The analysis and the design of the proposed control strategy are illustrated and a 2-kW experimental prototype is built to verify the analysis results. Experimental results show that the power factor of the three-phase boost PFC rectifier is improved significantly within wide ac input frequency range, e.g., 360–800 Hz. The proposed control strategy achieves satisfied performance when the ac input frequency varies.