A novel active snubber for high-power boost converters

A technique which improves the performance of the boost converter by reducing the reverse-recovery-related losses in the boost switch and rectifier with an active snubber that is implemented with a minimum number of components is presented. This minimum-component-count snubber consists of a snubber inductor, an auxiliary switch, and a rectifier. The proposed technique reduces the reverse-recovery-related losses by controlling the turn-off di/dt rate of the rectifier current with the snubber inductor connected in series with the boost switch and rectifier. The voltage and current stresses of the components in the proposed active-snubber boost converter are similar to those in its conventional “hard-switched” counterpart     

A soft switching active snubber optimized for IGBT's in singleswitch unity power factor three-phase diode rectifiers

This paper describes a soft switching active snubber for an IGBT operating in a single switch unity power factor three-phase diode rectifier. The soft switching snubber circuit provides zero-voltage turn-off for the main switch. The high turn-off losses of the IGBT due to current tailing are reduced by zero-voltage switching. This allows the circuit to be operated at very high switching frequencies with regulated DC output voltage, high quality input current and unity input power factor. Simulation and experimental results are included     

软开关隔离型升压DC-DC变换器设计与实现

为了满足升压型变换器低成本和大功率密度的需求,本文提出了一种软开关单极隔离型DC-DC变换器。该变换器电路包含一个无损耗缓冲器,通过漏电感固定住开关的电压峰值,从而实现开关的ZVS关断。在失谐状态下,使用Lr-Cr串联谐振电路来实现二极管的ZCS关断。由于磁化电流低,相较于传统的基于反激的变换器,变压器的容量更少。在输出功率250W和开关频率100kHz的条件下进行了实际测试,提出的变换器的最大测量效率为97.0%。     

A zero voltage transition boost converter employing a soft switching auxiliary circuit with reduced conduction losses

This paper presents a zero-voltage-transition (ZVT) boost converter using a soft switching auxiliary circuit for power factor correction (PFC) applications. The improvement over existing topologies lies in the positioning of the auxiliary circuit capacitors and the subsequent reduction in the resonant current and therefore the conduction losses as compared to other similar topologies. The proposed converter operates in two modes - Mode 1 and Mode 2. It is shown in the paper that the converter should be designed using the constraints obtained in Mode 1 to achieve low-loss switching. The converter is analyzed and characteristic curves presented which are then used in a detailed design example. Experimental results from a 250 W, 127 V input laboratory prototype switching at 100 kHz verify the design process and highlight the advantages of the proposed topology. The proposed converter is suitable for single-phase, two stage power factor correction circuits with universal input voltage range and power levels up to 3 kW.     

A novel Z-source boost derived hybrid converter for PV applications

Analog Integrated Circuits and Signal Processing - This paper proposes a novel Z-source boost derived hybrid converter (ZSBDHC) that produces high gain dual output from a single DC input, which is...     

A novel tri-state boost converter with fast dynamics

A challenging problem in the design of boost converters operating in continuous-conduction mode is posed by the dynamically shifting right-half-plane (RHP) zero in the converter's small-signal control-to-output transfer function. The paper proposes a novel tri-state boost converter without such a zero in the transfer function. The additional degree of freedom introduced in the converter in the form of a freewheeling interval has been exploited through an easy control technique to achieve this elimination. The absence of the RHP zero allows the control scheme to achieve larger bandwidth under closed-loop conditions, resulting in fast response. Analytical, simulation and experimental results of the tri-state boost converter have been presented and compared with those of the classical boost converter both under open-loop and under closed-loop operating conditions. The results clearly demonstrate the superior dynamic performance of the proposed converter. The proposed converter can be used in applications wherever fast-response boost action is needed.     

A single-switch continuous-conduction-mode boost converter with reduced reverse-recovery and switching losses

A single-switch continuous-conduction-mode boost converter with reduced reverse-recovery and switching losses is proposed. By utilizing the leakage inductances of a pair of coupled inductors and two additional rectifiers, the turn-off rates (di/dt) of the boost output rectifier and the additional rectifiers are slowed down to reduce the reverse-recovery loss. The boost power transistor is also operated under a low-voltage turn-on condition to reduce the switching loss. Experimental results are presented to confirm the theoretical analysis and the performance of the proposed converter.     

A zero-voltage transition boost converter using a zero-voltage switching auxiliary circuit

A soft switching boost converter with zero-voltage transition (ZVT) main switch using zero-voltage switching (ZVS) auxiliary switches is proposed. Various operating intervals of the converter are presented and analyzed. Design considerations are discussed. A design example with experimental results obtained from a 300-W, 250-kHz, 300-V output DC-DC converter is presented. A modified gating scheme to utilize the auxiliary switch in the main power processing is discussed. A 600-W, 100-kHz, 380 V output, 90-250 V AC, power factor corrected, AC-to-DC, boost converter with the modified gating scheme is presented. Results show that the main switch maintains ZVT while auxiliary switches retain ZVS for the complete specified line and load conditions. Parasitic oscillations existing in the converters proposed in the literature are completely removed.     

新型无源软开关变换器

普通的PWM变换器具有结构简洁、控制简单、频率恒定、输出特性好等优点,故广泛应用于社会生活的各个领域中.本文以boost基本电路为基础,采用简单的无源谐振网络,设计实现了开关管的软开关.这种新型的无源软开关解决了输出二极管反向恢复问题,具有结构简单、高频率、高效率、易于控制等优点.该设计可用于以IGBT为开关器件的高压场合.分析了该变换器的工作原理、实现条件、设计谐振网络的参数、并进行了仿真.     

一种新型交错并联同相降压升压DC/DC转换器

为了有效降低电流纹波和提高转换器效率,提出一种新型交错并联同相降压升压DC/DC转换器。提出的结构通过采用输入/输出（I/O）磁耦合交错并联和阻尼网络技术,降低了开关的电压应力、内部电压振荡和I/O电流纹波,并提升了转换器的效率。采用状态空间平均法,在连续导通模式下分析了提出转换器的稳态运行,从理论上证明了其优势。样机的功率设置为360W,输出电压为36 V,模拟结果以及实验结果显示,当输出电流为6A时,转换效率最高达到96%,最大输入电流纹波百分比仅为9.4%,相较于其他类似转换器,提出的转换器具有效率较高和I/O电流纹波较低的优势。     

Improved active power-factor-correction circuit using azero-voltage-switching boost converter

In this paper, a zero-voltage-switching (ZVS) scheme for a boost power converter is proposed and discussed. This lossless zero-voltage scheme is shown to improve the performance of active power factor correction circuits. The results are validated by both simulation and experimental results     

A generic soft switching converter topology with a parallelnonlinear network for high-power application

A soft switching concept that derives from the resonant link and resonant pole power converters and combines the best features of resonant and hard switching converters is applied to a phase arm. The inductor of the resonant LC is designed to saturate, thus having effectively two inductance values: a very large value during the conduction period and a small value that is only active during switching. The advantage of this technique is that a resonant tank with smaller continuous ratings can be used without giving up the component count advantage of resonant power converters. Another feature, contrary to other resonant topologies, is that semiconductor switches need not be overdimensional for voltage and current rating     

A new active clamping zero-voltage switching PWM current-fed half-bridge converter

A new active clamping zero-voltage switching (ZVS) pulse-width modulation (PWM) current-fed half-bridge converter (CFHB) is proposed in this paper. Its active clamping snubber (ACS) can not only absorb the voltage surge across the turned-off switch, but also achieve the ZVS of all power switches. Moreover, it can be applied to all current-fed power conversion topologies and its operation as well as structure is very simple. Since auxiliary switches in the snubber circuit are switched in a complementary way to main switches, an additional PWM IC is not necessary. In addition, it does not need any clamp winding and auxiliary circuit besides additional two power switches and one capacitor while the conventional current-fed half bridge converter has to be equipped with two clamp windings, two ZVS circuits, and two snubbers. Therefore, it can ensure the higher operating frequency, smaller-sized reactive components, lower cost of production, easier implementation, and higher efficiency. The operational principle, theoretical analysis, and design considerations are presented. To confirm the operation, validity, and features of the proposed circuit, experimental results from a 200-W, 24-200Vdc prototype are presented.     

A generalized Undeland snubber for flying capacitor multilevel inverter and converter

This paper proposes a snubber circuit for a flying capacitor multilevel inverter and converter. It also explains the concept of constructing a snubber circuit for a multilevel inverter and converter. The proposed snubber circuit makes use of an Undeland snubber as a basic snubber unit, and thus can be regarded as a generalized Undeland snubber for a flying capacitor multilevel inverter and converter. It has such an advantage of Undeland snubber used in the two-level inverter. Compared with a conventional RLD/RCD snubber for multilevel inverter and converter, the proposed snubber keeps such good features as fewer number of components, reduction of voltage stress of main switching devices due to low overvoltage, and improved efficiency of system due to low snubber loss. In this paper, the proposed snubber is applied to a three-level flying capacitor inverter, and its features are in detail demonstrated by computer simulation and experimental result.     

A novel lossless passive snubber for soft-switching boost-typeconverters

A novel lossless passive snubber is proposed for soft switching boost-type converters. The proposed snubber does not use any auxiliary switches, but uses two identical snubber capacitors which are charged in parallel at turn off of the main switch and discharged in series at turn on automatically, and the discharged energy is recovered effectively (more than 95% recovery) into the output capacitor. Thus, the snubber provides zero-voltage switching for the converter main switch, reducing both the turn-off losses and the electromagnetic interference (EMI) noise, which improves the converter performance. The experimental results of a 20 kHz 600 W DC-DC boost converter and a single-phase AC-DC boost rectifier with the new snubber are presented     

新型开关电源控制方法研究

VRM作为电压调节模块具有快速的动态响应性能,但传统的V2C控制方法有其固有的缺点。为了提高VRM的动态性能和鲁棒性,在此分析了传统控制方式的固有缺陷,并以传统Buck变换器为平台提出新的双闭环模糊PID控制方法,最终希望提高VRM的抗干扰性。提出的控制方法通过引入非线性的模糊PID控制器闭环稳定输出电压并引入PID负载电流控制器加快动态响应,同时在参数设置中尝试兼顾稳定性、快速动态响应性能和鲁棒性。最后通过仿真得到可以稳定输出的变换器电路并证明了该新型控制器具有良好的动态性能和控制精度。     

一种高效的同步整流Boost软开关变换器

针对同步整流Boost变换器的效率问题,提出一种同步整流Boost软开关拓扑。在辅助电路的帮助下,实现了主开关管的零电压通断和辅助开关管的零电流通断,显著改善了因开关管导致的变换器损耗严重的问题,使变换器的效率得到了有效提高。详细分析了所提变换器的工作原理并对主要参数的选取和变换器的特性进行了讨论,最后通过Pspice仿真实验对理论分析进行了验证。     

A high efficiency, soft switching DC-DC converter with adaptive current-ripple control for portable applications

A novel control scheme for improving the power efficiency of low-voltage dc-dc converters for battery-powered, portable applications is presented. In such applications, light-load efficiency is crucial for extending battery life, since mobile devices operate in stand-by mode for most of the time. The proposed technique adaptively reduces the inductor current ripple with decreasing load current while soft switching the converter to also reduce switching losses, thereby significantly improving light-load efficiency and therefore extending the operation life of battery-powered devices. A load-dependent, mode-hopping strategy is employed to maintain high efficiency over a wide load range. Hysteretic (sliding-mode) control with user programmable hysteresis is implemented to adaptively regulate the current ripple and therefore optimize conduction and switching losses. Experimental results show that for a 1-A, 5- to 1.8-V buck regulator, the proposed technique achieved 5% power efficiency improvement (from 72% to 77%) at 100 mA of load current and a 1.5% improvement (from 84% to 85.5%) at 300 mA, which constitute light-load efficiency improvements, when compared to the best reported, state-of-the-art techniques. As a result, the battery life in a typical digital signal processing microprocessor application is improved by 7%, which demonstrates the effectiveness of the proposed solution.     

一种新型软开关DC-DC PWM升压变换器设计

为提高转换效率并降低电源开关的电流应力,提出一种基于新型有源缓冲电路的PWM DC-DC升压变换器。该有源缓冲电路使用ZVT—ZCT软开关技术,分别提供了总开关ZVT开启及ZCT闭合、辅助开关ZCS开启及ZCT闭合。消除了总开关额外的电流及电压应力,消除了辅助开关电压应力,且有源缓冲电路的耦合电感降低了电流应力。另外,通过连续将二极管添加到辅助开关电路,防止来自共振电路的输入电流应力进入总开关。实验结果表明,相比传统的PWM变换器,新的DC-DC PWM升压变换器在满负荷时电流应力降低且总体效率能达到98.7%。     

Robust nonlinear control for boost converter

The standard current loop is modified for a boost converter to eliminate sensitivity of the control-to-output transfer function to the nature, and magnitude of resistive load. An additional term directly proportional to the load current and output voltage, and inversely proportional to the input voltage is added to the current loop. This results in practically invariant loop gains for different resistive loads, including constant power load