Harmonic resonant DC-DC converter for low coupling transformers

A new harmonic resonant DC-DC converter is proposed. The harmonic resonant converter is related to the multi-resonant converter and is used for transformers with low coupling. Two harmonic frequencies are present during any resonant state and the switch voltage can be less than two times the input voltage     

A novel self-excited forward DC-DC converter withzero-voltage-switched resonant transitions using a saturable core

A novel self-excited forward DC-DC power converter is proposed. The turn-on and turn-off of the switch are zero-voltage-switching with resonant transition. A saturable core is used to achieve the self-excitation and the zero-voltage-switched resonant transition. The voltage waveform across the switch is trapezoidal with sinusoidal transitions, and the current waveform flowing through the switch is quasisquare. The switching losses, the conduction losses and the stresses of the switch are significantly reduced in the proposed power converter. The output voltage is determined by the ON duty ratio of the switch as in a PWM converter. Two methods to modulate the ON duty ratio are proposed. Both methods results in variable-frequency operation. Experiments on two 5 V, 20 A DC-DC power converters show good performance     

Steady-state analysis of the series resonant DC-DC converter inconjunction with loosely coupled transformer-above resonance operation

This paper presents the steady-state analysis of the series resonant DC-DC power converter (SRC) in conjunction with loosely coupled transformer (LCT) operating above resonance (f_s/f_o>1). It is an extension of the conventional steady-state analysis of the SRC. Three operational modes other than the continuous current mode (CCM) have been identified, and the boundaries of all the operational modes are defined. Based on the well-defined operational plane, all the operational modes are analyzed. Results are given in normalized form and experimentally verified     

基于电流型DC-DC变换器建模与分析

为了推导建立电流型DC-DC变换器系统传递函数,采用电路平均法的处理方式对电流型正激DC-DC变换器进行平均和线性化处理,得到小信号等效电路模型,给出系统框图。应用网络分析仪Agilent4395A实测电路传递函数给出Bode图,从而去验证建模仿真的正确性。改变电路参数进一步验证建模仿真的通用性。实验结果验证了利用电路平均法得到的电流型DC-DC变换器模型的正确性和通用性。     

Phase control for resonant DC-DC converter with class-DE inverter and class-E rectifier

In this paper, a phase control scheme for Class-DE-E dc-dc converter is proposed and its performance is clarified. The proposed circuit is composed of phase-controlled Class-DE inverter and Class-E rectifier. The proposed circuit achieves the fixed frequency control without frequency harmonics lower than the switching frequency. Moreover, it is possible to achieve the continuous control in a wide range of the line and load variations. The output voltage decreases in proportion to the increase of the phase shift. The proposed converter keeps the advantages of Class-DE-E dc-dc converter, namely, a high power conversion efficiency under a high-frequency operation and low switch-voltage stress. Especially, high power conversion efficiency can be kept for narrow range control. We present numerical calculations for the design and the numerical analyses to clarify the characteristics of the proposed control. By carrying out circuit experiments, we show a quantitative similarity between the numerical predictions and the experimental results. In our experiments, the measured efficiency is over 84% with 2.5 W output power for 1.0-MHz operating frequency at the nominal operation. Moreover, the output voltage is regulated from 100% to 39%, keeping over 57% power conversion efficiency by using the proposed control scheme.     

A circuit model for the class E resonant DC-DC converter regulatedat a fixed switching frequency

An averaging circuit model is developed for the class E resonant DC-DC converter regulated at a fixed switching frequency. The regulation is achieved by use of an auxiliary switch. The model is obtained based on the circuit analysis using the Fourier series expansion. Steady-state and small-signal dynamic analysis is presented, which reveals that the DC output is well controlled by the control angle of the auxiliary switch and that there exists a right-half-plane zero in the control-to-output transfer function. The analysis results are verified by the experiments     

Electrothermal analysis of the self-excited push-pull DC-DC converter

The SPICE-aided electrothermal analysis of a self-excited push-pull DC-DC converter is considered in the paper. The new electrothermal model of a pulse transformer, which constitutes the basic component element of the considered converter, is proposed. This model contains among others: two different temperatures of the windings and the core, the influence of temperature on losses in the core and in the windings, the dependence of the magnetization curve on the core temperature, the Curie temperature, selfheating and mutual thermal interactions between the core and the windings. The semiconductor devices are described with the use of the hybrid electrothermal models. The measurements and electrothermal calculations of the characteristics of the investigated converter with the use of the models proposed in the paper are performed. A good agreement between the results of the calculations and the measurements achieved with this model testifies to correctness of the presented models.     

Steady-state analysis of a series-resonant DC-DC converter with abipolar power flow

A time-domain analysis for the steady-state model of a series-resonant power interface for both step-up and step-down modes is presented. The exchange of electrical energy between a source and the resonant circuit in order to stabilize the stored electrical energy is defined. The characteristics of a series-resonant converter with bilateral power flow are presented in normalized form, described by the output characteristics. The results obtained in a four-quadrant motor drive illustrate the characteristics of a high-frequency power interface     

Bidirectional phase-shifted DC-DC converter

A novel ZVS phase-shifted DC-DC converter is proposed. The converter operates at a constant switching frequency and the voltage conversion ratio is regulated by phase-shift control. It has bidirectional power flow capability and synchronous rectification, hence the on-state voltage drop of the devices is small. This is an ideal candidate for electric vehicles (EVs)     

Critical Q analysis of a current-fed resonant converter for ICPTapplications

Power electronic resonant converters designed for inductively coupled power transfer (ICPT) applications are normally controlled to switch at zero voltage switching (ZVS) frequencies and operate with minimal quality factor Q for economic and practical reasons. This Letter analyses various resonant frequencies and defines a new minimum bound on Q that ensures ZVS operation     

Design and analysis of switched-coupled-inductor switched-capacitor step-up DC-DC converter

The study presents a high-gain closed-loop configuration of switched-coupled-inductor switched-capacitor (SCISC) converter via integrating with a pulse-width-modulation-based (PWM) controller for the goal of step-up DC-DC conversion/regulation. The SCISC power part consists of switched-coupled-inductor booster (SCI booster) and switched-capacitor tripler (SC tripler), and the step-up voltage gain is performed by using appropriate duty ratio D of PWM and turn ratio n of coupled inductor. Although increasing n or raising D makes a higher gain, it often results in the larger weight/volume or magnetic bias/saturation of coupled inductor. Here, the SC tripler can provide for an extra gain to ease these stresses of the coupled inductor. Further, this controller is engaged not merely in doing topological operation and timing, but in enhancing output regulation and/or output robustness (against source/loading variation). The related studies are demonstrated as follows: modelling, steady-state response, voltage conversion ratio value, power efficiency, capacitance/inductance selection, system stability and control design. At the end, the simulation results are obtained to check the design/analysis validity, and the experimental results are verified on the prototype of SCISC to display the effect of the proposed scheme.     

驱动式DC-DC变换器设计

为了对直流电压进行变换,采用DC-DC技术,设计输出电压可调的直流电压变换器。变换器包括驱动式方波电路、功率管组成的调整电路、比较采样电路和滤波电路。在multisim软件环境下进行仿真,并在实际电路进行测试,获得的结果满足设计要求。实验证明,升压变换器可实现输入5 V直流电压,输出12 V直流电压;降压变换器可实现输入12 V直流电压,输出5 V直流电压;具有良好的直流变换功能。     

一种高效率双向DC-DC变换器的设计

文章以芯片TPS5430为核心构成DC-DC变换器,由51单片机组成测控电路,通过单元电路上的按键改变占空比来调节输出电压,辅助电源由直流稳压电源经过稳压芯片L7805CV输出5 V电源。整个系统充分利用了TPS5430过流保护和热关断功能,性能测试较为完善,比较好地实现了设计要求。     

A new ZVT-ZCT-PWM DC-DC converter

In this paper, a new active snubber cell is proposed to contrive a new family of pulse width modulated (PWM) converters. This snubber cell provides zero voltage transition (ZVT) turn on and zero current transition (ZCT) turn off together for the main switch of a converter. Also, the snubber cell is implemented by using only one quasi resonant circuit without an important increase in the cost and complexity of the converter. New ZVT-ZCT-PWM converter equipped with the proposed snubber cell provides most the desirable features of both ZVT and ZCT converters presented previously, and overcomes most the drawbacks of these converters. Subsequently, the new converter can operate with soft switching successfully at very wide line and load ranges and at considerably high frequencies. Moreover, all semiconductor devices operate under soft switching, the main devices do not have any additional voltage and current stresses, and the stresses on the auxiliary devices are at low levels. Also, the new converter has a simple structure, low cost and ease of control. In this study, a detailed steady state analysis of the new converter is presented, and this theoretical analysis is verified exactly by a prototype of a 1-kW and 100-kHz boost converter.     

A single-switch flyback-current-fed DC-DC converter

This work presents a novel DC-DC converter, whose significant advantages are the single power switch, single-input inductor, purely capacitive output filter, isolation, low current ripple through the output capacitor, and operation at constant frequency in a conventional pulse-width-modulation scheme. The new converter operates over a wide input-voltage range and can be employed in power factor correction and multiple-output power supplies. Theoretical analysis is presented along with experimental results taken from a laboratory prototype rated at 300 W/50 kHz     

A multiple-input DC-DC converter topology

A new topology for multiple energy source conversion is presented. The topology is capable of interfacing sources of different voltage-current characteristics to a common load, while achieving a low part count. A fixed frequency switching strategy is investigated and the resulting operating modes are analyzed. The analysis is verified by experimentation. The results show that the converter is an enabling technology for power diversification and optimization.     

A new ZVT-PWM DC-DC converter

In this paper, a new active snubber cell that overcomes most of the drawbacks of the normal "zero voltage transition-pulse width modulation" (ZVT-PWM) converter is proposed to contrive a new family of ZVT-PWM converters. A converter with the proposed snubber cell can also operate at light load conditions. All of the semiconductor devices in this converter are turned on and off under exact or near zero voltage switching (ZVS) and/or zero current switching (ZCS). No additional voltage and current stresses on the main switch and main diode occur. Also, the auxiliary switch and auxiliary diodes are subjected to voltage and current values at allowable levels. Moreover, the converter has a simple structure, low cost, and ease of control. A ZVT-PWM boost converter equipped with the proposed snubber cell is analyzed in detail. The predicted operation principles and theoretical analysis of the presented converter are verified with a prototype of a 2 kW and 50 kHz PWM boost converter with insulated gate bipolar transistor (IGBT). In this study, a design procedure of the proposed active snubber cell is also presented. Additionally, at full output power in the proposed soft switching converter, the main switch loss is about 27% and the total circuit loss is about 36% of that in its counterpart hard switching converter, and so the overall efficiency, which is about 91% in the hard switching case, increases to about 97%     

A multiple-switch high-voltage DC-DC converter

Series connection of power devices has evolved into a mature technique and is widely applied in HV DC power systems. Static and dynamic voltage balance is ensured by shunting individual devices with dissipative snubbers. The snubber losses become pronounced for increased operating frequencies and adversely affect power density. Capacitive snubbers do not exhibit these disadvantages, but they require a zero-voltage switching mode. Super-resonant power converters facilitate the principle of zero-voltage switching. A high-voltage DC-DC power converter with multiple series-connected devices is proposed. It allows the application of nondissipating snubbers to assist the voltage sharing between the multiple series-connected devices and lowers turnoff losses. Simulation results obtained with a circuit simulator are validated in an experimental power converter operating with two series-connected devices. The behavior of the series connection is examined for MOSFETs and IGBTs by both experimental work with a 2 kW prototype and computer simulation. Applications can be found in traction and heavy industry, where the soft-switching power converter is directly powered from a high-voltage source     

Characteristics of the multiple-input DC-DC converter

In the zero-emission electric power generation system, a multiple-input DC-DC converter is useful to obtain the regulated output voltage from several input power sources such as a solar array, wind generator, fuel cell, and so forth. A new multiple-input DC-DC converter is proposed and analyzed. As a result, the static and dynamic characteristics are clarified theoretically, and the results are confirmed by experiment.     

Steady-state analysis and design of the parallel resonant converter

Five basic operating modes of the parallel resonant converter are analyzed. Three of the modes occur when the output filter inductor is removed and the remaining two occur when the filter inductor is large. Closed-form solutions are found for the two most important modes. Analysis results are given graphically so that the designer can use them without lengthy calculation or computer iteration. Switching frequency, peak tank capacitor voltage, and peak tank inductor current are plotted in the output plane. These plots, with a load line superimposed, show how operating point, frequency, and peak stress vary as load conditions change. Use of the output plane plots to minimize component costs is explained. Comparison of the best designs found for the large and zero filter inductance cases shows that removing the filter inductor can reduce both parts count and tank circuit size while peak transistor current remains unchanged