一种高效率升压型ＤＣ－ＤＣ转换器设计

设计了一种基于PWM/PFM调制模式的全负载高效率升压型DC-DC转换器。根据负载不同,实现PWM和PFM模式的自动切换。轻载时,进入PFM模式,降低开关损耗,并加入电感峰值限流,减小输出电压纹波。在DCM状态下,利用休眠模式电路,降低静态功耗,同时提出一种抗振铃电路,进一步提升轻载转换效率。芯片实测结果表明,1mA轻载条件下,效率依然达到91.6%,输出电压纹波约为6.6 mV。全负载最高效率可以达到93.1%。     

可实现DVS的单电感双输出降压型直流-直流转换器

设计了一款单电感双输出(SIDO)的降压型直流-直流转换器,一个输出电压可以进行动态电压转换,在0.725～1.2V直接变化,另一输出电压可实现1.2V和1.8V,两路输出最大可实现500mA负载电流。转换器根据负载的不同在脉冲宽度调制(PWM)和脉冲频率调制(PFM)之间自动切换。采用死区时间自适应调整的技术来提高系统的转换效率,分段开关则用来降低输出端毛刺。基于TSMC0.25μm CMOS工艺,测试结果证明该系统输出电压纹波低、毛刺小,系统峰值效率可达90%。     

采用分段式自适应PWM/PFM调制的Buck型DC-DC转换器设计北大核心

为了在轻重负载条件下获得更高的转换效率，采用分段式结构和导通电阻更小的NMOS作为输入级，并采用PWM/PFM双调制方式，设计了一种Buck型DC-DC转换器。为解决PWM/PFM调制信号切换问题，采用零电流检测方式进行切换。利用断续导通模式(DCM)和连续导通模式(CCM)下端NMOS管导通时电感电压的不同，检测下端NMOS在导通时电感电压大于零的周期。当电感电压大于零的周期大于2时，则处于DCM模式并自动采用PFM调制模式，关闭一部分功率管以减小开关频率和功率管寄生电容，优化轻载效率；反之则处于CCM模式并采用PWM调制。仿真结果表明，在负载电流10～1 000 mA范围内，该电路可以在两种调制模式平稳切换，在800 mA时峰值效率可提升到96%以上。     

带纹波控制的全载高效率DC-DC变换器的设计

便携式通信设备对DC-DC变换器的轻载效率及输出电压纹波的要求较高,轻载时,降低频率可以提高效率,但会带来纹波的恶化。针对这种缺陷,深入研究了轻载下纹波与频率之间的关系,得到一种降低纹波的新颖方法—带电感电流峰值控制的PFM技术。基于CSMC 0.5μm标准CMOS工艺,完成了电路设计。仿真结果表明,与传统PFM相比,该方法显著减小了轻载时的输出电压纹波,减小幅度最高可达80%。     

一种PFM控制模式高效反激转换器的设计

设计了一种不连续导通模式(DCM)下高效反激式转换器的控制方案。该方案通过电压检测(VS)端电感检测功率MOS管的导通状态,通过控制电路对VS信号进行采样和保持,采样值输入至降频电路产生降频电流,降低振荡器的工作频率,从而减少功率MOS管的开关损耗,提高转换器的工作效率。在不同的输出负载下,VS的采样值产生不同大小的降频电流不同程度降低振荡器的工作频率,实现对系统的脉冲频率调制和脉冲宽度调制的结合控制。本电路采用0.5μm BiCMOS工艺,利用Hspice和Cadence软件对设计的电路进行仿真。仿真结果表明,转换器的效率高达86%,在0.1 A轻载情况下效率也达到了72.1%,较高的工作效率满足设计要求。     

轻载高效Buck转换器设计及其纹波控制方案

提出了一种峰值电流模式PWM下的轻载高效Buck DC-DC控制方案。该方案根据负载大小来自适应调节开关频率和电感电流峰值,实现宽负载范围内高的转换效率和对输出纹波的控制。把误差信号与负载自适应的门限相比较,以判定转换器工作模式。在轻载模式下,通过循环开启或者关闭振荡器来降低转换器的开关频率,降低开关损耗。详细推导了在保持输出电压纹波不变的情况下,负载自适应门限与负载大小之间的关系,并在典型应用下得到二者呈线性关系的结论。采用0.5μm BCD工艺进行仿真,结果显示,在输入电压12 V,输出电压3.3 V下,轻载时最高有94.2%的转换效率,在负载从10 mA到500 mA变化时,轻载模式纹波为120~140 mV,与理论分析的控制纹波130 mV较为符合。     

用于降压型DC-DC转换器的新颖过零检测电路

针对降压型DC-DC转换器需要工作在电感电流不连续导通模式(DCM)下的场合,设计了一个输出电压自适应的过零检测方案。该方案通过采集输出电压信息来调整检测到电感零电流后的响应时间,使其在输出电压很大时倒灌电流仍然很小。采用0.5μm BCD工艺,在8V输出电压下进行芯片级仿真,结果显示,与传统过零检测电路相比,新电路的倒灌电流减小了66%。     

电源

电源管理器AP3591在100~700k Hz之间的电阻编程固定频率下工作,其自适应恒定导通时间控制算法能够应付非常宽广的输入输出电压比,并有助于减少外部部件数量。这款器件的输入和输出电压范围分别为4.5~26V及0.75~5.5V;输出电流则高达25A。该控制器提供两种工作模式选择,包括可在轻载情况下自动降低频率和提升效率的二极管仿真模式,以及有效防止轻载输出纹波的恒定频率连续导通模式。新控制器采用了十四引脚QFN3535     

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。     

用于神经刺激器的单电感双极性直流电压转换器

提出了一种应用于神经电刺激器的单电感双极性输出(SIBO)的直流电压转换器,具有良好的轻载效率和较低的设计复杂度。提出的SIBO系统只使用一个电感,通过两相控制同时输出正负电压,降低了控制复杂度,减少了开关通断次数,提高了效率。同时使用数模混合电路、固定导通时间调制方式实现逻辑控制,提高了系统效率,降低了设计复杂度。SIBO系统采用单节锂电池供电,输入电压为3 V到4.2 V,输出电压在不同模式下可以分别输出 ±16 V、±12 V、±8 V、±4 V。后仿真结果表明,SIBO系统在输出电压为±16 V、负载电流为1 mA时,V_OP、V_ON的纹波分别为4.5 mV和3.4 mV;在负载电流为1.3 mA时,能够达到的最大效率为94.8%。具有效率高、纹波小、复杂度低等优势。     

A novel low quiescent current PFM method with independent threshold for buck switching converters

Efficiency is the key parameter of switching converters. Pulse frequency modulation (PFM) is often used to reduce the dynamic loss at the light load condition, while Pulse width modulation (PWM) is used in heavy load case. The efficiency at the heavy load is usually process dependent, however there are many circuits design considerations for the efficiency and other electrical performances improvement in the light load case. This paper will propose a method which can operate in the PWM in heavy load condition and automatically change to the PFM in light load condition with accurate PFM current threshold independent to input voltage, output voltage, switching frequency and inductor value. The adaptive accurate zero cross comparator (AAZCC) for DCM (discontinuous mode) and the method to achieve very low quiescent current consumption in the skip period are also introduced, those two are the points to further improve the efficiency in light or medium load conditions. A prototype has been designed with a 0.18 μm CMOS process.     

新颖的含PFC的PWM ZVS AC-DC变换器

提出了一种新的具有功率因数补偿(PFC)功能的零电压开关(ZVS)AC-DC变换器,该变换器基于不连续导电模式(DCM)下的Boost环节实现PFC功能,但其具有ZVS机制,从而解决了DCM下因开关关断大的峰值电流引起的关断损耗高、EMI严重的问题,同时还消除了由于开关的寄生电容引起的开通损耗.该变换器可以采用通用控制芯片并工作在PWM模式.文中分析了提出变换器的工作原理,并给出了基本设计原则.模拟和实验结果证明了提出的电路是可行的.     

The zero Voltage switching (ZVS) critical conduction mode (CRM) buck Converter With tapped-inductor

The critical conduction mode (CRM) control has some disadvantages such as the increase of switching loss and conduction loss of the main switch at extreme high/low voltage conversion applications. In this paper, a CRM buck converter with tapped inductor is proposed to overcome these problems. In this converter, both the active switch and the diode have soft switching operation by the resonance between the switch parasitic capacitors and the filter inductor. Furthermore, the peak current of the main switch is reduced by tapped inductor operation, thus the conduction loss and switching loss levels of the main switch are lowered. Consequently, this tapped inductor scheme with CRM control alleviates the severe power stress and enhances device utilization. For the proposed converter evaluation, this paper provides the operation analysis and design procedures of the converter, and also presents the hardware verification for a 50-W prototype operating at maximum 70 kHz. Finally, a new topology family derived by combination of CRM operation with the basic tapped-inductor converter is included.     

ZVT-PWM AC-DC boost converter with ZCS auxiliary circuit

A low conduction loss, low-cost zero-voltage-transition-pulsewidth modulation (ZVT-PWM) boost converter with a zero current switching (ZCS) auxiliary circuit is developed to achieve high-conversion-efficiency operation. The unique locations of the resonant capacitor and inductor ensure that low switching stress and commutation losses are obtained in this converter. It is very suitable for high power-factor-correction pre-regulators     

Analysis and Design of a Novel Three-Phase AC–DC Buck-Boost Converter

This paper proposes a novel three-phase ac-dc buck-boost converter. The proposed converter uses four active switches, which are driven by only one control signal. This converter is operated in discontinuous conduction mode (DCM) by using the pulsewidth modulation (PWM) technique, and the control scheme very easily and simply achieves purely sinusoidal input current, high power factor, low total harmonic distortion of the input current and step-up/down output voltage. Also, the proposed converter provides a constant average current to the output capacitor and load in each switching period. Thus, the ripple component of sixth times line frequency will not appear in the output voltage. Therefore, a smaller output capacitor can be used in the proposed converter. Moreover, the steady-state analysis of voltage gain and boundary operating condition are presented. Also, the selections of inductor, output capacitor and input filter are depicted. Finally, a prototype circuit with simple control logic is implemented to illustrate the theoretical analysis.     

MPPT控制Boost变换器的一种软开关实现策略

提出了最大功率点跟踪MPPT(Maximum Power Point Tracking)控制Boost变换器的一种软开关实现策略:将MPPT控制Boost变换器设计在断续导通模式DCM(Discontinuous Conduction Mode)下。首先推导了MPPT控制Boost变换器的等效负载,然后借助工作模式分析推导得到输入电感的临界值。设计输入电感为临界值就可以使得变换器在全输入电压范围内工作在DCM模式下,开关器件实现自然的软开关。最后,在PSIM软件中完成了仿真验证。     

一种BUCK型开关稳压器负载电流检测电路

针对Buck型开关稳压器的断续工作模式(DCM),基于CSMC0.5μm CMOS工艺设计实现了一种新颖的负载电流检测电路。同传统的电感电流采样方式不同,该结构直接应用与负载电流变化几乎同步的同步管栅极驱动信号作为"电流采样"信号,实现了负载平均电流的检测。经投片验证,提出的电流检测电路工作良好,且面积仅占芯片的1.5%,同传统采样方式相比,面积减小了21%,静态时的耗电仅为原来的40%。     

Fuzzy Switching Technique Applied to PWM Boost Converter Operating in Mixed Conduction Mode for PV Systems

Due to the variation of the maximum power point (MPP) of photovoltaic (PV) generators with solar radiation and temperature, boost DC-DC converters placed between PV modules and inverters in grid-connected PV systems have to be controlled in a variable operating-point condition. In addition, inductor current dynamics changes suddenly when moving from continuous to discontinuous conduction mode. The previous difficulties make the design of reliable and fast control laws for the input voltage of boost converters complicated. The aim of this paper is to propose a control algorithm based on cascaded-loop control. The input voltage is controlled by the outer loop. The inductor current is controlled by an inner loop strategy which is able to perform in mixed conduction mode, owing to the fuzzy switching technique. Simulation and experimental results for a 10-kW boost converter show that the proposed strategy achieves an accurate and robust performance at every operating point, even if the inductor value varies in a wide range; thus, fast MPP tracking techniques can be implemented. An additional advantage is that constant switching frequency is achieved.     

An Accurate, Low-Voltage, CMOS Switching Power Supply With Adaptive On-Time Pulse-Frequency Modulation (PFM) Control

Integrated switching power supplies with multimode control are gaining popularity in state-of-the-art portable applications like cellular phones, personal digital assistants (PDAs), etc., because of their ability to adapt to various loading conditions and therefore achieve high efficiency over a wide load-current range, which is critical for extended battery life. Constant-frequency, pulsewidth modulated (PWM) switching converters, for instance, have poor light-load efficiencies because of higher switching losses while pulse-frequency modulation (PFM) control in discontinuous-conduction mode (DCM) is more efficient at light loads because the switching frequency and associated switching losses are scaled down with load current. This paper presents the design and integrated circuit prototype results of an 83% power efficient 0.5-V 50-mA CMOS PFM buck (step-down) dc-dc converter with a novel adaptive on-time scheme that generates a 27-mV output ripple voltage from a 1.4- to 4.2-V input supply (battery-compatible range). The output ripple voltage variation and steady-state accuracy of the proposed supply was 5 mV (22-27 mV) and 0.6% whereas its constant on-time counterpart was 45 mV (10-55 mV) and 3.6%, respectively. The proposed control scheme provides an accurate power supply while achieving 2%-10% higher power efficiency than conventional fixed on-time schemes with little circuit complexity added, which is critical during light-loading conditions, where quiescent current plays a pivotal role in determining efficiency and battery-life performance