Synchronous Rectifier Circuit Research Articles

High-Performance Light Emitting Diode Lighting Circuits and Their Interior Design Applications

This study explores the application of the half-bridge Inductor-Inductor-Capacitor (LLC) resonant converter in Light Emitting Diode (LED) lighting driver power supplies, with a specific focus on improving efficiency and dimming capabilities. The investigation begins with an analysis of the sliding mode control (SMC) method, utilizing a constant-current design with a fixed switching frequency (FWF). A novel fuzzy frequency-selective SMC dimming strategy is proposed to recognize the challenge of significant output voltage ripple during dimming under a FSF. To address the ripple issue during dimming, an electromagnetic filtering circuit is designed, and a zero-voltage turn-on Metal—Oxide—Semiconductor (MOS) tube is introduced, incorporating a synchronous rectification scheme to mitigate losses in the secondary-side rectification diode. The study comprehensively considers a current-mode self-driven method, specifically tailored to the LLC circuit’s different operating modes. The LLC resonant circuit, along with the subsequent synchronous rectification circuit, is meticulously designed for a 252 W LED driver power supply prototype. A closed-loop simulation circuit model is developed using PSIM software in experimental validation. The feasibility of SMC based on a FSF is affirmed through a comparative analysis of SMC signal waveforms, steady-state output current (OC) models, and resonant tank current waveforms. The investigation into the OC under various SMC conditions demonstrates the half-bridge LLC resonant converter’s ability to achieve stable output with minimal ripple. The designed LED lighting circuit is applied to indoor design, providing adjustable LED brightness and switch status at different power levels. Although obstacles slightly impact the communication quality of the circuit, it remains suitable for the majority of users’ needs.

Optimized Design Method of RC Damper Based on Modified Negative Conductance Model to Suppress Switching Oscillations in Synchronous Rectifier Circuits With GaN Devices

Optimized Design Method of RC Damper Based on Modified Negative Conductance Model to Suppress Switching Oscillations in Synchronous Rectifier Circuits With GaN Devices

Phase-Shifted Full-Bridge ZVS DC-DC Converter with Synchronous Double Rectifiers for Battery Charging Applications

This paper presents a phase-shifted PWM-controlled DC to DC power converter with a synchronous double rectifier. The power switches can be directed to achieve the zero-voltage switching condition using the technology of the full-bridge power converter and increase the efficiency of the converter on the secondary side of the transformer. A current doubling rectifier with low current ripple and synchronized rectifier circuits are also adopted. The secondary side of the high-frequency transformer uses the synchronous double rectifier. The synchronous double rectifier circuit converts AC voltage to DC voltage to enable high-current applications with two filtering inductors to reduce losses and dissipate heat, resulting in an efficient system. The proposed method can control the input DC voltage of the phase-shifted power converter at 400 V and achieves the required DC voltage of 24 V for battery charging applications under the zero-voltage switching condition. The results of simulations and experiments show 86.7% efficiency at 40% load condition and 91.8% efficiency at full load condition.

Power-Estimation-Based Synchronous Rectification Solution for Bidirectional DAB-LLC Converter

An LLC-DAB bidirectional converter with reduced switch count as a DC-DC transformer (DCX) is proposed in this paper. It can achieve voltage regulation, full load range zero voltage switching (ZVS) for eight main switches and wide load range ZVS for four auxiliary switches, with consideration of the switch junction capacitors under different power direction. A part portion of total power is transferred through an auxiliary DAB circuit to achieve voltage regulation and bidirectional power conversion. The main power is transferred through LLC circuit with an easy PWM scheme achieving high conversion efficiency. Different from the existing LLC-DAB DCX structure, the two secondary side transformer outputs are in parallel, and connected to the same full-bridge circuit. In this way, the auxiliary DAB circuit can not only adjust the output voltage, but also can inject current into the secondary side to help achieving ZVS of switches without synchronous rectifier (SR) circuit. The converter operation principle is analyzed under different power directions, and ZVS is analyzed with the consideration of all the switch junction capacitors. Based on the analysis, the design consideration is introduced. Finally, a 2-kW prototype with 750V input and 400V output is built up to verify the effectiveness of the proposed solution.

An LLC-DAB Bidirectional DCX Converter With Wide Load Range ZVS and Reduced Switch Count

An LLC dual active bridge (DAB) bidirectional converter with reduced switch count as a dc–dc transformer (DCX) is proposed in this article. It can achieve voltage regulation, full load range zero voltage switching (ZVS) for eight main switches and wide load range ZVS for four auxiliary switches, with consideration of the switch junction capacitors under different power direction. A part portion of total power is transferred through an auxiliary DAB circuit to achieve voltage regulation and bidirectional power conversion. The main power is transferred through LLC circuit with an easy PWM scheme achieving high conversion efficiency. Different from the existing LLC -DAB DCX structure, the two secondary side transformer outputs are in parallel, and connected to the same full-bridge circuit. In this way, the auxiliary DAB circuit can not only adjust the output voltage, but also can inject current into the secondary side to help achieving ZVS of switches without synchronous rectifier circuit. The converter operation principle is analyzed under different power directions, and ZVS is analyzed with the consideration of all the switch junction capacitors. Based on the analysis, the design consideration is introduced. Finally, a 2-kW prototype with 750 V input and 400 V output is built up to verify the effectiveness of the proposed solution.

Self-Driven Current-Doubler Synchronous Rectifier and Design Tuning for Maximizing Efficiency in IPT Systems

A novel driving circuit for a current-doubler synchronous rectifier (SR) to inductive power transfer (IPT) applications is proposed in this article using only auxiliary windings in the existent rectifier output filter inductors to drive active switches. The proposed SR overcomes the limitations of the traditional driving schemes because it does not require any processing, analog circuits, gate driver circuits, or current measurement, normally used in the conventional SR applied to IPT systems. The proposed configuration presents a simple and robust operation considering usual parametric variation in IPT systems, such as coupling factor, misalignment, load variation, and component tolerances. Moreover, the same size and weight of the conventional diode rectifier board are maintained due to the simplicity of the self-driven circuit. The proposed configuration allows increasing the global efficiency by reducing the conduction losses of the output rectifier and previous stages. A resonant circuit design procedure using an iterative process to find the maximum efficiency point considering the self-driven SR is proposed to maximize the global system efficiency. A 100-W resonant series–parallel IPT prototype is developed to validate the performance of the proposed self-driven SR circuit presenting a maximum global efficiency equal to 94.8%.

Non-Linear Switching Circuit for Active Voltage Rectification and Ripples Reduction of Piezoelectric Energy Harvesters

This paper describes an improved non-linear switching circuit (INLSC) for active rectification of voltage and reduction of ripples in the voltage waveform for the piezoelectric energy harvesting (PEH) system. The proposed converter controls the alternating current (AC) generated by the piezoelectric device (PD) under mechanical vibration. The proposed circuit combines the boost and buck-boost processes through a switching process, which functions in both positive and negative cycles. In addition, it controls the voltage and frequency of the load capacitor. In this process, the passive components in the circuit are energised by being short with the AC voltage using switching signals, which facilitates the active rectification of ultra-low AC voltage. Design considerations, theoretical analysis, simulations and experimental results are presented. It was shown that the circuit was able to control the switching signal and to convert low AC voltage (0.44 Vi) to high direct current (DC) voltage (6.5 Vdc) while achieving an output power of 469 µW which outperforms the existing similar circuits and synchronous rectifier circuit. The ripples in the rectified voltage were also comparatively less. Application-wise, the proposed circuit could power a manually connected 7-segments display, commonly used for traffic applications.

Novel coupled analysis methods of automotive alternators considering synchronous rectification circuit

PurposeThe purpose of this paper is to develop a novel coupled analysis method for synchronous rectification alternators.Design/methodology/approachAn ideal diode module is embedded in a rectification circuit. The resistance of the diode module is set such that it is equal to the on-resistance of the MOS-FET modules in the generation mode. In a mode without power generation, the motor voltage is less than the bus voltage; a sufficiently large value is defined for simulating the infinite resistance.FindingsBecause there is no need to decide the switch timing in advance, only one round of coupled analysis is needed to evaluate the synchronous rectification alternators.Research limitations/implicationsAs limited case study is denoted in this paper, much more case studies are needed to be discussed.Practical implicationsBy using the proposed method, it can be fulfilled that generation characteristic of automotive alternators can be evaluated without using the control simulation or pre-conducted analysis to decide the switch timing.Social implicationsBy using the proposed method, it can be fulfilled that generation characteristic of automotive alternators can be evaluated without using the control simulation or pre-conducted analysis to decide the switch timing.Originality/valueIn the proposed methods, the definition of diode module differs from that of a conventional coupled analysis.

An integrated multimode battery charger in a Qi compliant wireless power receiver

In this paper, an integrated multimode battery charger in a Qi-compliant wireless power receiver is presented. The proposed wireless battery charger includes a synchronous rectifier circuit and a multi feedback low dropout regulator. The charging circuit automatically switches trickle current, constant-current, and constant-voltage mode corresponding to battery voltage. Through control of the target rectified voltage from the perspective of the wireless power receiver, the synchronous rectifier circuit can generate an adaptive rectified voltage to closely track the battery voltage, which significantly reduce the power loss in the charging circuit. The wireless battery charger was implemented with a TSMC 0.18 µm BCD 1P5M process and the experimental results show the charging current of constant-current mode is 1 A and the final voltage of the wireless battery charger is 4.2 V. The maximum efficiency of the overall system is 78%.

Feed‐forward control scheme to improve light‐load power factor for single‐stage flyback PFC converters

In this Letter, the author proposes a new feed-forward controller for single-stage flyback power factor correction (PFC) converters. By compensating the phase-lead effect caused by input capacitor current, the proposed feed-forward control duty improves the displacement factor as well as the distortion factor, and so the flyback PFC converter has high power quality. By means of the synchronous rectification circuit, the flyback PFC converter can operate in reverse when the negative current is required. To confirm the theoretical analysis and validity of the proposed control scheme, the author demonstrated the proposed control algorithm with 80 W flyback PFC converter prototype.

Duty-Ratio Feedforward Controller Design to Minimize the Capacitor Effect of the Flyback Inverter Under the Light-Load Condition

We propose a new duty-ratio feedforward controller for the flyback inverter with a synchronous rectifier (SR) circuit. For grid-connected photovoltaic power systems, the power factor (PF) of the output current must be high under most of the load conditions. To improve the PF of the flyback inverter even under light load, we propose a compensation method for the output capacitor current. The proposed method improves the displacement factor as well as the distortion factor, so the flyback inverter with the SR circuit has high power quality. By means of the SR circuit, the flyback inverter can operate in reverse when the negative current is required. The derivation of the proposed method is presented based on time-domain analysis. We also provide the boundary of the region where the proposed scheme should be adopted. The effectiveness of the proposed method is demonstrated in experiments with a 120-W rated power prototype.

DC Polarity Control in Radio Frequency Synchronous Rectifier Circuits

In this letter, two different switching modes are identified for RF synchronous rectifier circuits which lead to a change in the polarity of the rectified output voltage. The operation of the two modes is defined in terms of the dynamic current-voltage (I-V) characteristics of the switching device and the polarity of the output load voltage. In one mode, the dc output voltage is positive and associated with a switching condition where the device is ON in quadrant-III and OFF in quadrant-I. This mode of operation has been reported widely in the literature. In the second mode, the quadrants associated with the on- and off-state are swapped leading to a polarity reversal across the load. Theoretical justification for the two modes is given and the experimental results are shown to confirm the two different switching modes in the synchronous rectifier. Experiments with a GaN inverse class-F rectifier were made to verify the theory, and both modes have similar measured peak rectification efficiencies of 77% at a frequency of 1.8 GHz.

High-Efficiency Transcutaneous Energy Transfer for Implantable Mechanical Heart Support Systems

Inductive power transfer technology is a promising solution for powering implantable mechanical circulatory support systems, due to the elimination of the percutaneous driveline, which is still the major cause of severe infections. However, at the present time, no transcutaneous energy transfer (TET) system is commercially available and ready for long-term use. Specifically, the heating of the tissue due to power losses in the TET coils and the implanted electronic components are a major problem. The focus of this paper is, therefore, on the design and realization of a highly efficient TET system and the minimization of the power losses in the implanted circuits in particular. Parameter sweeps are performed in order to find the optimal energy transmission coil parameters. In addition, simple and meaningful design equations for optimal load matching are presented together with a detailed mathematical model of the power electronic stages. To achieve highest efficiencies, a high-frequency self-driven synchronous rectifier circuit with minimized volume is developed. Extensive measurements are carried out to validate the mathematical models and to characterize the performance of the prototype system. The optimized system is capable of transmitting 30 W of power with an efficiency greater than 95 %, even at a coil separation distance of 20 mm (0.79 in) and 70 mm (2.76 in) coil diameter.

A New Current-Driven Synchronous Rectifier for Series–Parallel Resonant ( $LLC$) DC–DC Converter

A new synchronous rectifier (SR) driving method is proposed using primary current sensing in this paper. Because the magnetizing current of transformer is included in the primary winding of transformer, it cannot be used to generate the driving signals of SRs directly. A current-compensating winding in current transformer (CT) is used to cancel out the magnetizing current and generate suitable driving signals for SR. Therefore, one CT is used to generate two driving signals for two SRs in LLC converter with a center-tapped rectifier. This current-driven method is simple and low cost for high-output-current dc-dc application. A 150-W dc-dc prototype using LLC half-bridge converter with the proposed SR circuit is built up to verify the theoretical analysis.

A low-cost CMOS dual-mode AC/DC data converter for signal measuring technique

A low-cost CMOS dual-mode AC/DC data converter for signal measuring technique is newly proposed. Instead of traditional full wave rectification, the realized synchronous rectification circuit is more attractive due to the easier integration and lower cost. In this paper, the design strategies of implementing the signal processing of AC and DC modes in the integrated circuit are discussed completely. Proven through SIMULINK in system level and SPICE simulations in circuit level, simulation results show that the proposed dual-mode AC/DC data converter achieves 8-bit resolution in DC mode and 7-bit resolution in AC mode. Measurement results have successfully verified the correct functions and performance of the proposed data converter and confirmed it for AC/DC signal measuring technique. The area of this chip is 710 × 630 μm2 and the measured power consumption is 5.1 mW. The proposed dual-mode AC/DC data converter is suitable for the system of analog and mixed-signal boundary scan.

Piezoelectric Micro-Power Generation Interface Circuits

New power conversion circuits to interface to a piezoelectric micro-power generator have been fabricated and tested. Circuit designs and measurement results are presented for a half-wave synchronous rectifier with voltage doubler, a full-wave synchronous rectifier and a passive full-wave rectifier circuit connected to the piezoelectric micro-power generator. The measured power efficiency of the synchronous rectifier and voltage doubler circuit fabricated in a 0.35-/spl mu/m CMOS process is 88% and the output power exceeds 2.5 /spl mu/W with a 100-k/spl Omega/, 100-nF load. The two full-wave rectifiers (passive and synchronous) were fabricated in a 0.25-/spl mu/m CMOS process. The measured peak power efficiency for the passive full-wave rectifier circuit is 66% with a 220-k/spl Omega/ load and supplies a peak output power of 16 /spl mu/W with a 68-k/spl Omega/ load. Although the active full-wave synchronous rectifier requires quiescent current for operation, it has a higher peak efficiency of 86% with an 82-k/spl Omega/ load, and also exhibits a higher peak power of 22 /spl mu/W with a 68-k/spl Omega/ load which is 37% higher than the passive full-wave rectifier.

Thin film magnetic field sensor utilizing Magneto Impedance effect

Recently, the Magneto Impedance effect found in amorphous wires with soft magnetic properties is noticeable as a new principle for sensing magnetic filed. According to this effect, the impedance of the wire in the range of high frequencies over 10 MHz changes remarkably with the external magnetic field. This effect is expected to be promising for magnetic field sensor with high sensitivity. Therefore, we have attempted to introduce this effect into amorphous thin films to extend application fields, and a novel thin film sensor sensitive to small magnetic field based on the Magneto Impedance effect has been proposed. The sensor consists of half bridge of the individual detecting element with FeCoSiB/Cu/FeCoSiB multi-layer, which exhibits the large impedance change ratio more than 100% when an external magnetic field is applied. By the optimization of the operating point due to bias field and the signal processing with a synchronous rectifier circuit, no hysteresis, good linearity and good stability against temperature variation as well as high sensitivity in the sensor characteristics have been achieved. The variation of the sensor output with the temperature is largely reduced to one-third, compared to the conventional thin film sensor we developed formerly. The detection resolution of 10 −3 Oe order higher than those of any other conventional thin film sensors is obtained.

A simple method for detecting torque of an induction motor with a synchronous rectifier circuit

A simple method for detecting torque of an induction motor with a synchronous rectifier circuit

A simple method for detecting torque of an induction motor with a synchronous rectifier circuit

There are many torque measuring methods for an induction motor. Some applications require a simple and easy method to detect torque change rather than a precise method to measure the torque of the motor. The torque of an induction motor is roughly estimated by the input current. This is the simplest method of measuring torque. The input current of the induction motor is the sum of the torque current and the exciting current. The torque current is proportional to the synchronous wattage and the motor torque. The exciting current has a phase lag of almost 90° behind the torque current, is variable with the input voltage, and is larger than the torque current, especially at a light load. Therefore, it is difficult to find the motor torque from the input current of the motor at a light load. In this paper, we propose a simple and easy torque measuring method with a synchronous rectifier circuit. The synchronous rectifier circuit can find the vector component at the detection angle from the input current of the induction motor and can detect the torque current in the input current of the motor. By adjusting the detecting angle of the synchronous rectifier, the rectified signal is mixed with the torque current and the exciting current in proper proportions and compensated for the fluctuation of the input voltage. This serves as a simple and easy torque measuring method suitable for trouble detection at loads such as in life testing. © 1999 Scripta Technica, Electr Eng Jpn, 126(3): 83–90, 1999

Simple Method for Detecting Torque of an Induction Motor With a Synchronous Rectifier Circuit.

There are many torque measuring methods for an induction motor. Some applications require a simple and easy method to detect torque change rather than a precise method to measure the torque of the motor. The torque of an induction motor is roughly estimated by the input current. This is the most simple method of measuring torque.The input current of the induction motor is the sum of the torque current and the exciting current. The torque current is proportional to the synchronous-watt and the motor torque. The exciting current has a phase difference of almost 90 degree lag to the torque current, is variable with the input voltage and is larger than the torque current especially at a light load. Therefore, it is difficult to find motor torque from the input current of the motor at a light load.In this paper, we propose a simple and easy torque measuring method with a synchronous rectifier circuit. The synchronous rectifier circuit can find a vector component at the detecting angle from the input current of the induction motor and detect the torque current in the input current of the motor. Adjusting the detecting angle of the synchronous rectifier, the rectified signal is mixed with the torque current and the exciting current in proper persentage and compensated for the fluctuation of the input voltage. It serves as a simple and easy torque measuring method suitable for trouble detection of the load such as under the life test.