Two-phase Interleaved Buck Converter Research Articles

Discontinuous Conduction Mode Analysis of Two-Phase Interleaved Buck Converter With Inversely Coupled Inductor

Discontinuous Conduction Mode Analysis of Two-Phase Interleaved Buck Converter With Inversely Coupled Inductor

A Compact Double-Sided Cooling 650V/30A GaN Power Module With Low Parasitic Parameters

Compared with silicon and silicon carbide devices, the unique electrical and structural characteristics of gallium nitride high electron mobility transistors (GaN HEMTs) make them have different requirements for power module integration. This article proposes a novel integration scheme for the high-voltage lateral GaN HEMT dies without bonding wires. Based on the proposed integration scheme, a compact 650 V/30 A GaN power module with low parasitic parameters and high thermal performance is designed. The GaN dies are sandwiched between two ceramic substrates to improve thermal performance and ensure consistent thermal expansion coefficients. The multiple copper layer structure is used to increase wiring flexibility to reduce parasitic parameters. The design of gate and power loop layouts is discussed, and the common-mode (CM) capacitance is optimized. A comprehensive reliability evaluation is also carried out for this integration scheme. Finally, a double-sided cooling 650 V/30 A full-bridge GaN power module with 2.4 cm×1.3 cm×0.17 cm is fabricated. The thermal resistance is reduced by 30%–48% compared with the conventional single-sided cooling module. The power loop and gate loop inductances are reduced to 0.94 nH and 2 nH, respectively, and the CM capacitance is limited to 2.5 pF. The maximum d <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">v</i> /d <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">t</i> of the drain–source voltage is high as 150 V/ns with only 10% overshoot. Based on the power module, a 3.3-kW two-phase interleaved buck converter is developed. It has 820 W/in <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sup> power density and 98.85% peak efficiency.

Minimization of Output Voltage Ripple of Two-Phase Interleaved Buck Converter with Active Clamp

A control technique combining pulse width modulation (PWM) and pulse amplitude modulation (PAM) is presented herein to reduce the output voltage ripple of the converter as little as possible. Such a converter requires a two-stage cascaded structure. The first stage is the buck-boost converter, which is used to adjust the output voltage of the second power stage, whereas the second stage is the two-phase interleaved buck converter, which is used to reduce the output voltage ripple. In theory, the two phases of the second stage operate under the condition of individual duty cycles of 50% with a phase difference of 180° between the two, and hence, the currents in the two phases are cancelled for any period of time, thereby making the output voltage of the converter almost voltage-free. Moreover, in order to improve the overall efficiency further, the proposed soft-switching technique based on an active clamp is presented and applied to these two stages to render the main and auxiliary switches turned on with zero-voltage switching (ZVS). Finally, the operating principles and control strategies of the proposed converter are described, and then, their effectiveness is verified by experimental results.

Two‐phase high efficiency interleaved buck converter with improved step‐down conversion ratio and low voltage stress

A two-phase interleaved buck converter (IBC) providing a high step-down conversion ratio is proposed in this study. The proposed IBC uses a switch-capacitor cell to achieve a high step-down conversion ratio compared to the conventional IBC. The cell consists of two parallel switches and two crossly placed identical capacitors. These identical capacitors are charged in series and discharged in parallel by producing a lower output voltage compared to the conventional IBC at the same duty ratio. The proposed converter provides less voltage and current stresses. The operation principle, the ripple and the average current through the inductors are described in continuous conduction mode. The boundary load condition is also determined. By describing the charging and discharging of the two identical capacitors of the cell, the capacitance value is determined. The losses and efficiency are analysed, and 96.33% efficiency is achieved. Finally, the proposed converter is implemented and experimental results are provided.

Optimal Design of Planar Magnetic Components for a Two-Stage GaN-Based DC–DC Converter

This paper develops a 200-W wide-input-range (64-160-to-24-V) rail grade dc-dc converter based on gallium nitride devices. A two-stage configuration is proposed. The first regulated stage is a two-phase interleaved buck converter (>400 kHz), and the second unregulated stage is an LLC (2-MHz) dc transformer. In order to achieve high frequency and high efficiency, the critical-mode operation is applied for the buck converter, and the negative coupled inductors are used to reduce the frequency and the conduction losses. Then, a systematical methodology is proposed to optimize the planar-coupled inductors. For the unregulated LLC converter, it can always work at its most efficient point, and an analytical model is used to optimize the planar transformer. Finally, the proposed dc-dc converter, built in a quarter brick form factor, is demonstrated with a peak efficiency of 95.8% and a power density of 195 W/in <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sup> .

Mechanism Analysis and Closed Loop Simulation of Two-phase Interleaved BUCK Converter

Interleaved Buck converters can increase power level and improve converter efficiency under the same stress conditions. Based on the two-phase interleaved buck converter model, several working conditions are analyzed in detail. The current ripple is deduced by the current-voltage relationship. Then the loss model is established to calculate and compared the efficiency of the the single phase and two intersecting converter. Finally, the closed-loop simulation analysis is carried out by MATLAB. The experimental results show that the converter combined with the double closed loop algorithm reduces the ripple current and improves the robustness of the system.

Soft Switching Converter with Output Voltage Ripple Minimized

In this study, a control technique combining the pulse amplitude modulation (PAM) and the pulse width modulation (PWM) is presented to minimize the output voltage ripple of the proposed converter. The proposed converter is a two-stage structure. The first stage, used to adjust the input voltage of the second stage, is an active clamp buck-boost converter, and the second stage, used to reduce the output voltage ripple, is a two-phase interleaved buck converter with an active clamp based on only one resonant circuit. Furthermore, the output voltage ripple can be cancelled when the two-phase interleaved buck converter operates under the condition of individual duty cycles of 50% with a phase shift of 180o. Moreover, both the first stage and second stage converters can achieve zero voltage switching (ZVS). Therefore, compared with hard switching control, the efficiency can be improved. Above all, the number of phases can be extended. Finally, the operating principles and experimental results are provided to verify the performance of the proposed converter.

A Novel Transformerless Interleaved High Step-Down Conversion Ratio DC–DC Converter With Low Switch Voltage Stress

In this paper, a novel transformerless interleaved high step-down conversion ratio dc-dc converter with low switch voltage stress is proposed. In the proposed converter, two input capacitors are series-charged by the input voltage and parallel-discharged by a new two-phase interleaved buck converter for providing a much higher step-down conversion ratio without adopting an extreme short duty cycle. Based on the capacitive voltage division, the main objectives of the new voltage-divider circuit in the converter are for both storing energy in the blocking capacitors for increasing the step-down conversion ratio and reducing voltage stresses of active switches. As a result, the proposed converter topology possesses the low switch voltage stress characteristic. This will allow one to choose lower voltage rating MOSFETs to reduce both switching and conduction losses, and the overall efficiency is consequently improved. Moreover, due to the charge balance of the blocking capacitor, the converter features automatic uniform current sharing characteristic of the interleaved phases without adding extra circuitry or complex control methods. The operation principles and relevant analysis of the proposed converter are presented in this paper. Finally, a 400-V input voltage, 25-V output voltage, and 400-W output power prototype circuit is implemented in the laboratory to verify the performance.

Design of Ultrathin LTCC Coupled Inductors for Compact DC/DC Converters

It is found out that using reverse coupled inductors could effectively improve power density and dynamic performance of multiphase interleaved point of load converters. Thus, it is of great significance to conduct a research about design and fabrication of ultrathin coupled inductors for system 3-D integration. The aim of this paper is to explore the structures, modeling, and fabrication of ultrathin coupled inductors based on low-temperature cofired ceramic (LTCC) technology. Four structures classified by shapes and relative positions of windings are introduced and compared. Simple but effective analytic models are set up to calculate self-inductance, leakage inductance, and coupling coefficient for quick design, and a design guideline is summarized according to the models. We made a 1.3-mm-thick LTCC coupled inductor and two competing coil coupled inductors, and compared their characteristics and performance. They are tested in a 12-V input and 1.2-V/40-A output two-phase interleaved buck converter at three different switching frequencies. Core loss and winding loss of the inductors are quantified by simulation. Compared with conventional coil coupled inductors, the LTCC coupled inductor has higher power density and light load efficiency. Besides, it could also help to improve the transient performance of converters for its higher coupling coefficient.

Current Sharing and Sensing in $N$-Paralleled Converters Using Single Current Sensor

Current sensing is one of the important functions in a dc-dc converter. It may be used for overcurrent protection, current control, or load sharing among paralleled converters. Current sharing (CS) can be achieved by sensing the output currents of individual converters, but it requires current sensors. In this paper, a current-sensing and CS scheme that uses a single sensor to sense the individual currents is presented. The scheme is independent of the number of converters in the paralleled system. The proposed scheme can be implemented easily on a digital platform and provides various functionalities of a voltage-regulating module. The analysis and implementation issues for such a scheme are presented and experimentally verified on a 1-V/25-A two-phase interleaved buck converter with digital control.