Center-tapped Rectifier Research Articles

A Novel Center-Tapped Rectifier With Current-Balancing and Voltage-Clamped Capability for LLC Resonant Converter

A Novel Center-Tapped Rectifier With Current-Balancing and Voltage-Clamped Capability for LLC Resonant Converter

Analysis of two-section phase-controlled resonant voltage converter

Analysis of two-section resonant DC-to-DC converter with phase power control is carried out in this paper. Two-section converter is considered as a boundary case of the multi-section converter with only one controlled section and other uncontrolled sections. The converter sections are parallel resonant half-bridge voltage inverters with a common resonant capacitor connected to the load through a matching transformer, center-tapped rectifier and smoothing filter. One of the sections is the reference, relative to which the phase shift of the output pulses of the other section is adjusted. The switching frequency of the converter is constant, which improves its electromagnetic compatibility. Analysis is carried out by the fundamental harmonic approximation method. Analytical expressions for voltage and current phasors in both sections of the converters have been established. The dependence of the converter power on the phase shift between the pulses of the half-bridge inverter sections was obtained. The dependence of the efficiency of the converter on the power was analyzed. It is shown that the efficiency slightly decreases when the power is reduced in a wide range of powers and only at powers less than 10% of full load power it drops sharply. The problems of operation of section transistor switches in their zero-voltage switching mode is considered. Verification of the conducted analysis was carried out by simulation of the converter circuit using the PSIM program for modeling power electronics devices. The simulation results are in a good agreement with the analysis results.

Zero-Voltage Switching Full-Bridge Converter With Reduced Filter Requirement and Wide ZVS Range for Variable Output Application

In this article, a novel zero-voltage switching (ZVS) full-bridge converter is proposed to overcome the disadvantages of traditional phase-shifted full-bridge (PSFB) converter. In the proposed converter, a half-bridge (HB) converter with center-tap rectifier (CTR) is integrated into the traditional PSFB converter by sharing the lagging-leg switches and output filter. The HB converter operates with full duty cycle to ensure continuous energy transmission and the output voltage is regulated by adjusting the phase-shifted time of full-bridge (FB) converter. The proposed converter has many advantages such as reduced filter requirement, wide ZVS range and low primary circulating current. In addition, the rectifier in the proposed converter is composed of a full-bridge rectifier section and a CTR section. This feature makes the proposed converter well appropriate for the medium output voltage applications. Key operation principle and characteristics are fully discussed in this article. The effectiveness of proposed converter is verified using a 1.2 kW prototype circuit with 280 V input voltage and 60–120 V output voltage.

Voltage Multiplier with High Input/Output Voltage Gain from Center-Tap Rectifier-Voltage Tripler and Quadrupler

This paper proposes new rectifiers in the center-tap transformer to provide higher input/output (I/O) voltage gain with an equal transformer turns-ratio in the LLC resonant converter: a voltage tripler rectifier and a voltage quadrupler rectifier, which have simple structures with one capacitor and two diodes, and three and four times higher I/O voltage gain than a center-tap rectifier, respectively. Each rectifier is compared in terms of the transformer turns-ratio and the magnetizing offset current, and the voltage and current stresses in the capacitors and diodes. The validity of these proposed rectifiers in the half-bridge (HB) LLC resonant converter is confirmed by the experimental results from a 100 V/200 W output prototype.

Design and Current Unbalance Control Method for a Center-Tapped LLC Resonant Converter on UHD TV

This paper proposes a control algorithm for solving the unbalanced current of the primary side in an LLC converter that uses a center-tap rectifier on the secondary side in ultra-high definition TV applications. The current imbalance in the LLC converter using a center-tap rectifier causes thermal problems, low efficiency, and uncontrollability. The operational principle, primary side control algorithm, and design equation required to solve these problems are presented. The experimental results are presented to verify the efficiency and thermal improvement of proposed control algorithm.

A Dual Half-Bridge Converter With Hybrid Rectifier for DC Power Supply in Railway Systems

Dual half-bridge (DHB) converter is a recent innovation in the family of full-bridge converters, and it can achieve higher efficiency compared to the traditional converters. The DHB converters with center-tapped rectifier (CTR) and full-bridge rectifier (FBR) have been adopted in low ( 200 V) output voltage applications, respectively. However, the output voltage is between 100 and 200 V in some applications, such as auxiliary railway dc power supply, both CTR and FBR can be the candidate and it is very indistinct to select the matched rectifier. To suit for such specific application, this article proposes a DHB converter with hybrid rectifier (Hyb-R). The Hyb-R is composed of a CTR section and an FBR section, which are connected in series by sharing two diodes. As a combined structure, the voltage stress of Hyb-R is between that of FBR and CTR, which makes Hyb-R well appropriate for dc power supply in railway systems. In this article, the operational principle and performance of the proposed converter are analyzed in depth. Three prototypes based on the DHB converters with CTR, FBR, and Hyb-R are built and tested, respectively. Experimental results show that the proposed converter can achieve a superior efficiency compared with other converters.

Copper loss reduction for Plate Shape One Turn Coil in High Step-Down Center-Tapped rectifier Tomohide Shirakawa＊, Kazuhiro Umetani＊, Eiji Hiraki

In order to reduce copper loss, high step-down DC-DC converter often employs center-tapped rectifier. In addition, a plate shape one turn coil is utilized for transformer for making a high step-down ratio. We focused on the proximity effect in plate shape one turn coil, and investigate the cause of worsening the copper loss. In this paper, based on this investigation, we propose rectification method using winding integrated with rectifier. In addition, we discuss practical issues of the proposed method and present the solution strategy. The proposed method is verified by experiments, which suggests the effectiveness of the proposed method to high current applications.

Resonant Converter with Voltage-Doubler Rectifier or Full-Bridge Rectifier for Wide-Output Voltage and High-Power Applications

This paper presents a resonant converter with the benefits of wide output voltage, wide soft switching characteristics for power devices and high circuit efficiency. Since the series resonant circuit is adopted on the primary side, the power switches are turned on under zero voltage switching and power diodes on the secondary side can be turned off under zero current switching. To overcome the drawback of narrow voltage operation range in the conventional resonant converter, full-bridge rectifier and voltage-doubler rectifier topologies are employed on the secondary side for low-voltage output and high-voltage output applications. Therefore, the voltage rating of power devices on the secondary side is clamped at output voltage, rather than two times output voltage, in the center-tapped rectifier circuit. Synchronous power switches are used on the secondary side to further reduce the conduction losses so that the circuit efficiency can be further improved. To verify the theoretical analysis and circuit performance, a laboratory prototype with 1 kW rated power was built and tested.

Bidirectional DC Converter with Frequency Control: Analysis and Implementation

In this paper, a direct current (dc) converter with the abilities of bidirectional power transfer and soft switching characteristics is studied and implemented. The circuit schematic of the developed dc converter is built by a half-bridge converter and a center-tapped rectifier with synchronous rectifier. Under forward power transfer, a half-bridge circuit is controlled to regulate the low-voltage side at a stable value. For backward power transfer, a center-tapped rectifier with synchronous rectifier is regulated to control the high-voltage side at the desired voltage value, and the half-bridge circuit is operated as a voltage doubler rectifier. Active power devices are operated at zero-voltage switching using a series resonant technique on the high-voltage side with frequency modulation and inductive load operation. The practicability of the developed converter is established from experiments with a laboratory prototype circuit.

An Innovative Design: MOS Based Full-Wave Centre-Tapped Rectifier

A novel, more competent, low leakage and comparatively high speed full-wave centre-tapped rectifier is introduced with minimum distortion. Proficient and exploratory combinations of PMOS---PMOS or NMOS---NMOS logic are utilized to design full-wave centre-tapped rectifier. The scrupulous PMOS---PMOS logic with augmented stacked NMOS transistor is communal form of two PMOS and one NMOS transistor. The main motive of manipulating these circuits is to maintain the substrate biasing during circuit operation. The substrate biasing refers the exploitation in which substrate and drain/source terminal of a transistor is kept in reverse biasing mode. Due to utilization of modified MOS structure after replacing of diode, efficiency of full-wave centre-tapped rectifier is increased up to 20 % with compare to p-n junction diode based full wave centre-tapped rectifier and leakage power dissipation is reduced up to 57 %. The proposed circuit is designed to utilize the body effect properly to reduce the total leakage power of the circuit. The novelty of proposed circuit is the uniqueness of combination of MOS. Due to this; the proposed circuit has impressive resultant parameter with compare to other circuits and previous results. Proposed MOS based full-wave centre-tapped rectifier is optimized at 45 nm CMOS technology and cadence simulation experimental implementations of the leakage power and efficiency demonstrate better consistency through the proposed circuit.

Hybrid DC–DC Converter With Phase-Shift or Frequency Modulation for NEV Battery Charger

This paper suggests a new hybrid dc–dc converter for a neighborhood electric vehicle battery charger. The proposed converter is based on the conventional phase-shift full-bridge (PSFB) converter with center-tap rectifier. By integrating an $LLC$ series resonant converter into the conventional PSFB converter, the proposed converter has many advantages like wide soft-switching range without duty-cycle loss, zero-current-switching operation of rectifying diodes, minimized circulating current, reduced size of filter inductor, and much better transformer utilization than before presented hybrid dc–dc converters. The proposed converter can be modulated in phase-shift manner or frequency variation. The feasibility of the proposed converter has been verified with the experimental results under an output voltage range of 36–72 V dc at 1 kW.

A New Center-Tapped Half-Bridge Zeta Converter With Small Transformer DC-Offset Current and Low Voltage Stress

In this paper, an asymmetrical half-bridge (AHB) converter employing a new center-tapped zeta rectifier (CTZR) is proposed to achieve a high efficiency in wide-input-voltage and low-output-current applications. Due to the proposed CTZR with high dc conversion ratio and extended maximum duty cycle above 0.5, the transformer turns ratio of the proposed converter can be increased, which decreases the transformer dc-offset current compared with that of the AHB converter. Therefore, its transformer core size is decreased. Moreover, it has a wide zero-voltage-switching range with small transformer leakage inductor, which improves light and medium load efficiency. Furthermore, since it has low voltage stress on the secondary diode, its conduction loss can be reduced. In addition, due to the elimination of a diode, the snubber loss in the secondary side is reduced compared with the AHB converter. Therefore, the proposed converter can achieve a higher efficiency compared with the AHB converter without additional devices. To confirm the operation, features, and validity of the proposed converter, a 250–400 V input and 50 V/250 W output laboratory prototype is built and tested.

A High Step-Down Multiple Output Converter With Wide Input Voltage Range Based on Quasi Two-Stage Architecture and Dual-Output <italic>LLC</italic> Resonant Converter

In this letter, a quasi two-stage architecture is proposed for wide input voltage range (voltage ranges ≈ 1:2) and high step-down multiple output conversion. A dc-DCX, which operates as a dc-dc converter with regulated output when the input voltage is low and as a dc-dc transformer with unregulated output when the input voltage is high, is adopted in the first stage to provide optimized intermediate dc-bus voltages for the second-stage point-of-load converters. The input and output of the dc-DCX are in series and connected to the total input voltage. Hence, part of the input power is directly transferred to the intermediate bus without conversion. The devices' voltage stresses and the transformer turns ratio of the dc-DCX are reduced by using the proposed quasi two-stage architecture. Thus, the conversion efficiency is improved significantly. Furthermore, a dual-output LLC resonant converter with hybrid center-tapped and full-bridge rectifier is proposed for the dc-DCX to achieve high efficiency and high power density. A 100-W prototype with three outputs is built and tested to verify the analysis.

Parallel asymmetric pulse‐width modulation converters with same power switches for medium power applications

A new zero-voltage switching (ZVS) half-bridge converter with three circuit modules is presented in this study to reduce the switching losses of power switches and current stress of passive components for medium power applications. Three circuit modules with the same power switches are connected in parallel at input and output sides. Thus, the switch counts are reduced compared with the parallel half-bridge converter with the same power rating. Each circuit module supplies one-third of load power to output side. Owing to the half-bridge converter leg, the voltage stress of each power switch is clamped at input DC voltage. Three centre-tapped rectifiers are adopted at low voltage side to share load current and reduce the size of magnetic cores. Asymmetric pulse-width modulation is adopted to regulate output voltage at the desired voltage level. Owing to the resonant behaviour by resonant capacitance [or output capacitance of metal-oxide semiconductor field-effect transistors (MOSFETs)] and leakage inductance (or external inductance) at the transition interval, power MOSFETs can be turned on under ZVS. The system analysis, circuit characteristics and design example of the proposed converter are discussed in detail. Finally, experiments with a 1620 W prototype are provided to verify the effectiveness of the proposed converter.

Interleaved ZVS DC/DC Converter with Balanced Input Capacitor Voltages for High-voltage Applications

A new DC/DC converter with zero voltage switching is proposed for applications with high input voltage and high load current. The proposed converter has two circuit modules that share load current and power rating. Interleaved pulse-width modulation (PWM) is adopted to generate switch control signals. Thus, ripple currents are reduced at the input and output sides. For high-voltage applications, each circuit module includes two half-bridge legs that are connected in series to reduce switch voltage rating to <TEX>$V_{in}/2$</TEX>. These legs are controlled with the use of asymmetric PWM. To reduce the current rating of rectifier diodes and share load current for high-load-current applications, two center-tapped rectifiers are adopted in each circuit module. The primary windings of two transformers are connected in series at the high voltage side to balance output inductor currents. Two series capacitors are adopted at the AC terminals of the two half-bridge legs to balance the two input capacitor voltages. The resonant behavior of the inductance and capacitance at the transition interval enable MOSFETs to be switched on under zero voltage switching. The circuit configuration, system characteristics, and design are discussed in detail. Experiments based on a laboratory prototype are conducted to verify the effectiveness of the proposed converter.

Analysis and Implementation of a New ZVS DC Converter for Medium Power Application

This paper presents a new zero voltage switching (ZVS) converter for medium power and high input voltage applications. Three three-level pulse-width modulation (PWM) circuits with the same power switches are adopted to clamp the voltage stress of MOSFETs at <TEX>$V_{in}/2$</TEX> and to achieve load current sharing. Thus, the current stresses and power ratings of transformers and power semiconductors at the secondary side are reduced. The resonant inductance and resonant capacitance are resonant at the transition interval such that active switches are turned on at ZVS within a wide range of input voltage and load condition. The series-connected transformers are adopted in each three-level circuit. Each transformer can work as an inductor to smooth the output current or a transformer to achieve the electric isolation and power transfer. Thus, no output inductor is needed at the secondary side. Three center-tapped rectifiers connected in parallel are used at the secondary side to achieve load current sharing. Compared with the conventional parallel three-level converters, the proposed converter has less switch counts. Finally, experiments based on a 1.44kW prototype are provided to verify the operation principle of proposed converter.

Analysis and implementation of a zero‐voltage switching asymmetric pulse‐width modulation converter for high load current application

A soft-switching converter using low voltage and low current stresses of power components is presented for high input voltage and high output current applications. Two input capacitors and four power metal-oxide semiconductor field effect transistors (MOSFETs) are adopted at high voltage side in order to reduce the voltage stress of power switches. Thus, the voltage stress of MOSFETs is clamped at V in /2. Two flying capacitors are adopted at the AC side of two half-bridge converter legs to balance the two input capacitor voltages. Three centre-tapped rectifiers are used at low voltage side in order to share load current and reduce the size of magnetic core and current stress of passive components. Asymmetric pulse-width modulation is used to generate the gate signals of power MOSFETs and regulate output voltage. Based on the resonant behaviour at the transition interval, all power switches can be turned on under zero voltage switching. Finally, experiments are provided to verify the effectiveness of the proposed converter.

Zero voltage switching DC converter for high‐input voltage and high‐load current applications

A new DC/DC pulse-width modulation (PWM) converter with the functions of zero voltage switching (ZVS) for power switches and zero current switching (ZCS) for rectifier diodes is presented for high-input voltage and high-load current applications. Three-level PWM circuit with two clamped diodes and one flying capacitor is adopted to achieve ZVS turn-on for all power switches, to balance two input capacitor voltages and to limit the voltage rating of each switch at one-half of input voltage. Two three-level PWM circuits with the same power switches are used to share the load current for medium power applications. Series–parallel resonant converter or LLC (L r, L m and C r) converter is adopted to achieve ZCS turn-off for rectifier diodes. Thus, the switching losses of power switches are reduced and the reverse recovery losses of rectifier diodes are eliminated. In order to high load current application, four centre-tapped rectifiers are connected in parallel to reduce the current rating of rectifier diodes and transformer windings. Experiments are provided to verify the effectiveness of the proposed converter.

New ZVS DC--DC Converter With Series-Connected Transformers to Balance the Output Currents

A new zero-voltage switching (ZVS) dc converter for high input voltage and high output current applications is presented in this paper. Two three-level pulse-width modulation (PWM) circuits with the same active switches connected in parallel at the output side are adopted to achieve load current sharing and to decrease current stress of rectifier diodes. The center-tapped rectifiers are adopted at the secondary side to have only one diode conduction loss in the forward current path. The series resonant tank of three-level converter is used to achieve ZVS turn-on for all power switches and zero-current switching for all rectifier diodes within nearly entire load range. Thus, the switching losses of power switches are reduced and the reverse recovery losses of rectifier diodes are eliminated. In order to overcome the drawback of a wide range of switching frequency in conventional series resonant converters, the fixed frequency pulse-width modulation is adopted to regulate the output voltage. The series-connected transformers are used in the primary and secondary sides to share and balance the load current. Finally, experiments based on a laboratory prototype are provided to verify the operation principle and demonstrate the effectiveness of the proposed converter.

Analysis, Design, and Implementation of a Soft-Switching Converter With Two Three-Level PWM Circuits

This paper proposes a new soft-switching circuit for high-input-voltage applications to achieve zero voltage switching (ZVS), implement load current sharing, reduce the voltage stress of switches at <formula formulatype="inline" xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex Notation="TeX">$V_{\rm in}$</tex></formula> /2, and decrease current rating of the rectifier diodes and the output inductors. Two three-level pulse-width modulation (PWM) circuits with the same active switches are operated with the phase-shift PWM scheme. Two center-tapped rectifiers are adopted at the secondary side such that the current rating of the transformer windings, rectifier diodes, and output filter inductors are reduced and have only one diode conduction loss in the forward current path. Based on the resonant behavior by the output capacitance of active switches and the leakage inductance (or external inductance), all power switches are turned ON at ZVS. The operation principle, circuit analysis, and design example are discussed in detail. Finally, experiments with 1-kW prototype are provided to verify the effectiveness of the proposed converter.