一种PWM/伪PFM双模调制的降压型DC/DC开关电源

利用根据负载电流的大小变换调制模式的方法实现了一种降压型高转换效率的DC/DC开关电源.当控制电压占空比小于20%时,采用伪PFM(pseudo-pulse-frequency modulation)模式调制;占空比大于20%时,采用PWM(pulse-width modulation)模式调制,平均转换效率约为90%,输出电流范围为0.01～3.0A.控制芯片采用0.5μm DPDM CMOS工艺制造,并采用二次集成的方式在封装内部集成了功率p-MOSFET.     

Dual sepic PWM switching-mode DC/DC power converter

A steady-state analysis and experimental results for a dual sepic pulse-width-modulated (PWM) DC/DC power converter for both continuous and discontinuous modes of operation are presented. The converter is dual to a sepic converter, but it can also be derived from a forward converter by replacing one of its rectifier diodes with a coupling capacitor. The circuit acts as a step-down or step-up converter, depending on the value of the ON switch duty cycle. The transformerless version of the converter has a positive DC/DC voltage transfer function. Therefore, the circuit is suitable for distributed power systems. Design equations for all circuit components are derived. Experimental results measured at 100 kHz were in good agreement with theoretical predictions     

一种同步整流DC-DC转换器PWM控制电路设计

设计了一种改进的PWM控制电路,将电流采样电路和PWM比较器归结为一个PWM电流比较器,减少了电路规模。将误差放大器输出与锯齿波斜坡补偿信号叠加,产生叠加输出电流,并通过PWM电流比较器输出一个占空比信号,以控制功率管的通断。电压信号转换为电流信号,从而使控制回路反应速度更快。将PWM控制电路应用于一款BUCK型DC-DC同步整流开关电源稳压器中。HSPICE仿真表明,稳压器输出纹波电压为±4mV,输出电压精度为±1%。     

Spectral characteristics of randomly switched PWM DC/DC convertersoperating in discontinuous conduction mode

This paper addresses a comparative study of the spectral characteristics of four random-switching schemes that apply to the basic pulsewidth-modulation (PWM) DC/DC converters operating in discontinuous conduction mode (DCM). They include randomized pulse position modulation, randomized pulsewidth modulation, and randomized carrier frequency modulation with fixed duty cycle and with fixed duty time, respectively. Mathematical models that characterize the input current and output voltage of the three basic PWM converters operating in DCM are derived. In particular, the effectiveness of spreading the dominant switching harmonics in the input current that normally exist in the standard PWM scheme and the introduction of low-frequency harmonics in the output voltage with respect to the randomness level are investigated. The validity of the models and analyses are confirmed experimentally by using a DC/DC buck converter     

水情遥测系统电源设计

文章介绍了一种供水情遥测系统使用的开关电源电路,利用脉宽调制的方法,将发电系统输出的直流信号变换成一个有可变占空比的方波信号,通过改变DC／DC变换电路的占空比,调节负载特性,从而将输出电压稳定在12V。试验证明：该电路稳定性好、输出电压精度较高并且能很快稳定,能较好地满足水情遥测系统供电需求。     

Technique for sensing inductor and DC output currents of PWM DC-DCconverter

The design, analysis and trade-offs of a novel method to sense the inductor and DC output currents of PWM converters are presented. By sensing and adding appropriately the currents in the transistor, rectifier and capacitors of a converter using current transformers, the waveforms of inductor and DC output currents can be reconstructed accurately while maintaining isolation. This method offers high bandwidth, clean waveform, practically zero power dissipation and simple circuit. The technique is applicable to all PWM converters in both continuous and discontinuous modes, and is most suitable for the implementation of current mode control schemes like hysteretic, PWM conductance control, and output current feedforward. This approach has been experimentally verified at a wide range of current levels, duty cycles, and switching frequencies up to 1.4 MHz     

A voltage mode buck DC–DC converter with automatic PWM/PSM mode switching by detecting the transient inductor current

This paper presents a voltage mode buck DC–DC converter that integrates pulse-width modulation (PWM) and pulse-skipping modulation (PSM) to achieve high efficiency under heavy and light load conditions, respectively. Automatic mode-switching is implemented simply by detecting the voltage drop of high-side power switch when it is on, which indicates the transient current flowing through the inductor. Unlike other methods based on average current sensing, the proposed auto-mode switching scheme is implemented based on voltage comparison and simple control logic circuit. In order to avoid unstable mode switching near the load condition boundary, the mode switching threshold voltage is set differently in PWM and PSM mode. Besides, a 16-cycle counter is also used to ensure correct detection of the change in the load condition and fast response of the converter. In addition, a dual-path error amplifier with clamp circuit is also adopted to realize loop compensation and ensure 100 % duty cycle operation. Fabricated in a 0.18-μm standard CMOS technology, the DC–DC converter is able to operate under supply voltage from 2.8 to 5.5 V with 3-MHz clock frequency. Measurement results show that the converter achieves a peak efficiency of 93 %, and an output voltage ripple of less than 40 mV, while the chip area is 1.02 mm².     

一种应用于DC/DC转换器的高效PWM控制电路的设计

本文提出一种用于DC/DC转换器的高效PWM控制电路。该控制电路采用电流控制模式,在宽范围内有着良好的瞬态响应。斜坡补偿信号与误差放大器的输出信号进行叠加,叠加后的信号与电流采样信号进行比较,产生一个占空比信号控制功率管的通断。并且本PWM控制电路中的误差放大器与软启动结合在一起,实现输出电压平滑稳定上升,有效减少了输入电流和输出电压过冲现象,保护了系统安全。     

Parallel resonant DC link circuit-a novel zero switching losstopology with minimum voltage stresses

A parallel resonant DC link (PRDCL) circuit topology is proposed as an approach to realizing zero switching loss DC-AC high switching frequency power conversion. The proposed circuit is used as an interface between the DC voltage supply and a voltage source pulse width modulated (PWM) inverter to provide a short zero voltage period in the DC link of the inverter to allow zero voltage switchings to take place in the PWM inverter. The peak voltage stress on the PWM inverter switches is limited to the DC supply voltage. Another significant advantage of the circuit is that the inverter can be controlled by the conventional PWM strategy. The proposed circuit is systematically analyzed and its operation principle is explained. Design considerations and design formulas are presented. A complete zero voltage switching DC-AC system consisting of the proposed circuit and a PWM inverter was simulated on a computer     

PS—FB—ZVSPWM DC／DC变换器中副边占空比丢失问题的研究

移相控制ZVSPWM DC／DC全桥变换器是变换器的一个研究热点,诸如高性能、高效率、低噪声、低污染等理论问题急待研究。副边占空比丢失是移相全桥PWM DC／DC变换器中的一个重要现象,文章以移相全桥ZVSPWM DC／IX;变换器电路模型为基础,结合变换器谐振电路的工作特点,对变换器副边占空比丢失的原因进行了详尽的分析,阐述了全桥变换器滞后臂比超前臂更难实现ZVS的原因,最终得到了移相全桥ZVSPWM DC／DC变换器死区时间和工作频率的设置条件与解决副边占空比丢失的措施。     

直流电机PWM调速系统中控制电压非线性研究

研究了直流电机PWM调速系统中控制电压的非线性,以实现精确的控制。通过实验和理论分析研究了空载情况下电机端电压平均值与电机转速、PWM波占空比与电机端电压平均值之间的非线性关系。实验表明,在不带电机情况下,PWM波占空比与控制输出端电压平均值之间呈线性关系;加入电机后,由于PWM在低电平期间电压的底端值不为0,所以占空比与电机端电压平均值之间呈抛物线关系。     

Switching flow-graph nonlinear modeling method formultistate-switching converters

Switching power converters operating in a multistate switching mode (more than two states) feature multidimensional control over their state variables. In this paper, a large-signal multistate modeling method is developed based on the switching flow-graph method to study the steady-state and dynamic properties of pulse-width-modulated (PWM) multistate-switching power converters for the continuous conduction mode. This modeling method translates a switching power converter directly to its graphic dynamic model and uses graphical representation to reveal the cause and effect relationship of the dynamics within a multidimensional power converter. A three-state buck-boost circuit is conceived with two duty ratios controlling two outputs as an example to test this modeling method. Experimental results confirm the theoretical prediction. This multistate-switching flow-graph modeling method is very general, easy to use and accurate, and it provides deep physical insight for engineering design     

Decoupled technique for the simulation of PWM switching regulatorsusing second-order-output extrapolations

A hybrid time-domain simulation technique for pulse-width-modulated (PWM) switching regulators is presented. The methodology integrates the advantages of the simulation concepts for switched and nonswitched networks. A regulator is decoupled into dual-analysis components, namely, the power conversion stage (PCS) and feedback network (FN). The former component is simulated by a time-domain digital integration technique with stepwise analysis of the switches' state and automatic determination of correct topological configuration in the PCS operation while the latter one is analyzed by formulating a modified system difference equation and defining at each switching period with second-order extrapolations and corrections of the PCS and error amplifier outputs. Other superior features of this approach include: (1) elegant numerical method of determining the gate signals from the PWM modulator; (2) simple manipulations of numeric and algebraic equations; and (3) applicability to simulate regulators with multiple parameters feedback from PCS. The proposed methodology is illustrated with several examples. The simulated steady-state and large-signal transient waveforms are favorably verified with experimental measurements and available literature     

一种高效的PWM开关电源控制新技术

研究了一款新型的脉宽调制(PWM)控制电路,该电路结构将传统的误差放大器,斜坡补偿和峰值电流检测电路转化为一个多输入的求和比较器来实现。从而使DC/DC转换结构变得简单,并且能够避免传统结构在PWM比较器输出的占空比大于50%时的稳定性问题。经HSpice仿真验证后得出该电路可适用于各种高精度DC/DC开关电源。     

用于电压模式的DC-DC转换器的前馈电路

提出了一种应用于电压模式的DC-DC降压转换器的前馈电路.传统DC-DC中,工作状态的变化,通过输出端反馈后才能对占空比做出调整;输入电压跳变时,调整时间就比较长.通过引入输入电压前馈通路,克服了传统结构调整时间过长的缺点.该电路应用在一种高效率、低功耗双模式DC-BC降压转换器芯片中,芯片采用CSMC公司的0.5 μm CMOS混合信号工艺设计和流片.实际测试结果表明在反馈环路中引入前馈支路后,没有影响系统环路的稳定性,而使线性调节性能(Line Regulation)得到显著的改善.     

A novel high efficiency low ripple switched-capacitor DC/DC converter

This paper presents a new method to improve light load efficiency and minimize output ripple of switched-capacitor (SC) DC/DC converters. In order to improve light load efficiency, this paper proposes adaptive frequency modulation to scale down gate-drive losses as load current reduces. Adaptive duty cycle modulation is proposed to minimize output ripple as the converter works under different gain hopping mode. Furthermore, this work optimized switching frequency, the dead time of 2-phase non-overlapping clocks and switching transistor size for efficiency enhancement. A new compensation circuit is also proposed to make system stable. A transistor level implementation of the proposed SC converter in Chartered 0.35 μm CMOS process is provided. Measurement results shows: maximum ripple voltage is <8 mV and efficiency is up to 87%.     

Steady-state analysis and design of a buck zero-current-switchingresonant DC/DC converter

An analytic basis is provided for a buck high-efficiency high-frequency zero-current-switching resonant DC/DC power converter. The current and voltage waveforms are derived for the steady-state operation. Design equations are then introduced for the switch duty cycle, maximum switching frequency, DC transfer function, peak currents and voltages, output power, and power conversion capability. Finally, the design procedure is presented along with the advantages and disadvantages of the converter, which are discussed in detail     

A novel PWM control for a bi-directional full-bridge DC–DC converter with smooth conversion mode transitions

A novel CMOS integrated pulse-width modulation (PWM) control circuit allowing smooth transitions between conversion modes in full-bridge based bi-directional DC–DC converters operating at high switching frequencies is presented. The novel PWM control circuit is able to drive full-bridge based DC–DC converters performing step-down (i.e. buck) and step-up (i.e. boost) voltage conversion in both directions, thus allowing charging and discharging of the batteries in mobile systems. It provides smooth transitions between buck, buck-boost and boost modes. Additionally, the novel PWM control loop circuit uses a symmetrical triangular carrier, which overcomes the necessity of using an output phasing circuit previously required in PWM controllers based on sawtooth oscillators. The novel PWM control also enables to build bi-directional DC–DC converters operating at high switching frequencies (i.e. up to 10?MHz and above). Finally, the proposed PWM control circuit also allows the use of an average lossless inductor-current sensor for sensing the average load current even at very high switching frequencies. In this article, the proposed PWM control circuit is modelled and the integrated CMOS schematic is given. The corresponding theory is analysed and presented in detail. The circuit simulations realised in the Cadence Spectre software with a commercially available 0.18?µm mixed-signal CMOS technology from UMC are shown. The PWM control circuit was implemented in a monolithic integrated bi-directional CMOS DC–DC converter ASIC prototype. The fabricated prototype was tested experimentally and has shown performances in accordance with the theory.     

PWM/PFM双模调制的高效率DC/DC开关电源

利用根据负载电流的大小改变调制模式的方法实现了一种降压型高转换效率的DC/DC开关电源,并采用二次集成的方式在芯片内部集成了功率p-M O SFET。当控制电压占空比小于20%时,采用PFM(Pu lse-F requency M odu lation)模式调制;占空比大于20%时,采用PWM(Pu lse-W idth M odu lation)模式调制,平均转换效率约为93%,输出电流范围可以从0.01 A到3.0 A。当输出驱动电流为3.0 A时,整个调制控制电路的功耗仅为6.0 mW。输入电压为5 V时,负载调整率小于1.5%;负载电流为0.01 A时,线性调整率小于0.5%。