一种基于求和比较器的峰值电流控制结构

提出了一种基于求和比较器的峰值电流控制结构。该结构使用一个PWM求和比较器,同时实现了电压和电流的双环反馈及斜坡补偿。对求和比较器的外围电路进行了匹配和优化设计,该结构使开关电源的输出电压精度、稳定性和动态响应速度都得到了提高。经验证,采用该控制结构,输出电压精度可达到±1%以内,输入调整率和负载调整率分别为0.1%/V和0.1%/mA。该控制结构可广泛用于各种高性能DC/DC开关电源。     

应用于DC/DC变换器的模拟伪三型补偿结构

介绍了一种采用模拟伪三型的补偿电路,该补偿电路可应用于DC/DC变换器中。通过在PWM比较器前把一个产生低频极点的全差分电路和一个产生低频零点的电路相加,得到两个低频零点和一个低频极点,进而得到快速的负载响应速度。在标准CMOS工艺下仿真了一个应用了伪三型补偿结构的DC/DC变换器,结果表明,在400 mA的负载电流阶跃时,负载调整率和线性调整率均小于2%。     

一种基于DC/DC变换器的LED驱动电路的设计

提出一种基于电流模式DC/DC变换器的驱动控制电路。该电路可以与恒流电路结合在一起,用作LED驱动。电路由误差放大器、斜坡信号产生电路、电流采样与叠加电路以及PWM比较器四部分构成。采用华虹BCD350工艺进行仿真验证,结果显示,电路成功实现了电流采样信号与斜坡补偿信号的叠加,在Vea信号的控制下,输出了控制功率管关断的PWM脉冲信号。     

一种DC/DC转换器的短路保护电路设计

针对负载短路会对DC/DC造成性能不稳定或损坏的情况,提出一种新型短路保护电路,有效地避免了传统电路在短路时大电流输出造成的能量浪费。该保护电路采用在负载短接时,通过改变电流限比较器输入端基准电压达到降低电路最大输出电流的措施。采用0.35 μm BCD工艺将该电路应用于一款高压同步BUCK型DC/DC转换器中,specter仿真结果表明,当负载短路时,该芯片的短路电流只有30 mA,与传统保护电路相比,降低了短路时的输出电流,达到节约能量的目的。     

全桥PWM—DC／DC变换器谐振技术的发展动态

介绍高频隔离全桥PWM DC/DC变换器电路结构,谐振软开关技术发展趋势。     

一种采用双极工艺设计的过流过压保护电路

文章提出了一种基于2μm双极型工艺设计的过流过压保护电路,本电路采用一个带迟滞比较器电路结构思想实现其保护功能的,本电路的结构新颖、电路简洁、性能优良.通过Cadence Soectre仿真工具对电路的工作状态进行仿真,结果表明该电路功能良好、敏感度高、便于集成.本过流过压保护电路通常用于集成在DC/DC转换器的控制芯...     

降压型PWM DC/DC中的峰值电流环电路的设计

设计了一种用于PWM降压型DC/DC的峰值电流环电路,详细地阐述了电路工作原理以及相关计算公式,设计了与之配套的功率管MOSFET的版图布局布线。该电流检测与信号放大电路结构简单,比传统的设计更精确地反映了峰值电流的大小。仿真结果表明,电路的电源调整率达到0.1%;在较大的电源范围内(4.75V~15V)增益保持不变。     

一种电流模式多输入可控PWM比较器设计

提出了一种用于PWM(Pulse Width Modulation)控制器的比较器输出电路的设计,该电路基于电流模式控制,能够同时对三路输入信号进行比较输出并对输出信号进行锁存。为了在PWM控制电路启动的时候让输出脉冲占空比从小到大逐渐变化,比较器电路设计采用了一个反相输入端,两个同相输入端,其中一个同相输入端控制PWM比较器是否产生输出信号,从而可以降低开关频率,对PWM控制电路起到保护作用。仿真和测试结果显示该比较器能有效地控制PWM输出,并且占空比范围宽、延迟时间短。     

单片降压型DC-DC转换器的控制电路设计

基于峰值电流检测脉宽调制技术原理,设计了一种新颖的应用于单片降压型DC-DC转换器的控制电路。针对峰值电流采样和PWM比较器电路技术,提出了一种新颖的电路结构。其中,PWM比较器和逻辑及驱动电路由升压电路驱动,节省了一个电平转换电路,降低了电路功耗;PWM比较器直接对功率管和镜像管电流采样,无需使用运算放大器,简化了电路结构。采用华虹宏力BCD350GE工艺进行设计,流片测试表明,电路可实现3V到36 V宽幅输入,500 mA满载输出。在输入24 V电压,输出3.3 V电压时,纹波为2.3 mV。     

基于动态参考的超低功耗动态PWM比较电路

提出了一种具有动态参考功能的高灵敏度、超低功耗PWM比较电路。该电路采用动态参考和多路径正反馈动态比较器,使连续的输入信号比较后生成一串离散数字信号,逻辑处理后转成占空比变化的脉冲。基于65 nm CMOS工艺,在1.2 V电源电压、200 MHz时钟频率下,对该电路进行了验证。结果表明,该电路的整体延迟时间有所增加,平均电流为5.958 μA,分辨率为800 μV。功耗仅8.1 μW,为传统静态PWM比较器的5.2%。     

单相两级有源功率因数校正变换器的研究

文中对两级有源功率因数校正变换器进行研究,设计了一台510W两级式开关电源。该电源前级采用平均电流控制的Boost型PFC电路,实现功率因数校正;后级采用不对称半桥型DC／DC变换器,实现开关管的零电压开关。控制电路采用PFC／PWM复合控制芯片ML4824,缩小电源体积。通过实验证实该开关电源具有高功率因数与高效率的特点。     

电流型零电压开关节能整流器

为解决电流型脉冲宽度调制（Pulse Width Modulation,PWM）整流器在高开关频率下硬切换时的开关损耗问题,提出了一种电流型零电压开关节能整流器,其辅助谐振电路位于直流环节,且与直流母线并联,只有1个辅助开关.在换流过程中,主开关能实现零电压切换,辅助开关能实现零电流切换,而且当整流器采用多电平PWM控制策略时,辅助电路在每个开关周期只需工作1次.分析了谐振换流过程,仿真结果表明特征仿真波形符合理论分析,开关器件切换时处于软开关状态,整流器能平稳运行.该电流型零电压开关节能整流器可以在高开关频率和大功率的应用场合实现高效率运行.     

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.     

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     

DC/DC开关变换器滑模变结构控制的新方案

本文在滑模等价控制的基础上,考虑实际控制中的非理想切换条件,提出了一种适合PWM型DC/DC开关变换器的滑模变结构控制算法简单的新方案.该控制算法依开关工作周期,动态地对滑模误差进行修正,从而动态地补偿控制量的大小,将有利于近似地保证系统沿着切换面运动,并可以减少系统稳态误差,达到削弱乃至消除高频抖动的目的.以Boost变换器为例的仿真结果表明,本文的控制方案可以减少系统超调,缩短过渡过程时间,改善系统的动态品质,并有效地解决滑模控制中的高频抖动问题.     

High efficiency, unity power factor VVVF drive system of aninduction motor

A high-efficiency, unity-power-factor VVVF (variable voltage, variable frequency) drive scheme for an induction motor is presented. A unity-power-factor PWM (pulsewidth modulated) converter regulates DC voltage. An inverter circuit with the magnetic flux control PWM method generates VVVF PWM waveforms. The modulation factor of the inverter PWM control with controllable DC link DC voltage is studied. As a result, the distortion factor and the switching frequency are reduced by over-modulation with low DC link voltage. A high-efficiency and unity-power-factor VVVF induction motor drive has been achieved using the control strategy     

A single-stage three-phase boost-buck AC/DC converter based ongeneralized zero-space vectors

In this paper, first a set of generalized zero-space vectors is proposed. Based on this concept, a novel single-stage three-phase pulsewidth modulation (PWM) boost-buck AC/DC converter is then proposed to achieve clean sinusoidal input current, unity power factor, adjustable DC voltage and fixed switching frequency and to be insensitive to input voltage distortion as well as simplify the control of all switches. By choosing proper switching sequences such that the largest magnitude line current is conducted through the antiparallel diodes without switching action, the switching loss and thermal stress can be reduced greatly. Finally, a prototype is constructed, and experimental results are given to validate the proposed converter     

Performance improvement of soft-switched PWM rectifiers withinductive load

A new soft-switched AC/DC pulse width modulation (PWM) converter structure is presented. It is useful for current-fed inverters and PWM rectifiers. Typical applications are magnet power supplies, high-power AC motor drives, and active power filters with magnetic energy storage. Soft switching is provided at the expense of a limited increase of the circuit complexity as compared to usual hard-switching solutions. A discussion of the soft commutation process is presented. By a proper switching sequence, overvoltages across the converter switches can be fully eliminated. Moreover, light-load operation can be achieved. Both typical limitations of soft-switched current-fed topologies are therefore overcome. Simulation and experimental results demonstrate the actual converter capabilities     

Resonant link bidirectional power converter. I. Resonant circuit

This paper proposes a novel resonant circuit capable of PWM operation with zero switching losses. The resonant circuit is aimed at providing zero voltage intervals in the DC link of the PWM converter during the required converter device switching periods, and it gives minimum DC bus voltage stresses and minimum peak resonant current. It requires only two additional switches compared to a conventional PWM converter. It is observed that the resonant circuit guarantees the soft switching of all the switching power devices of converters including the switches for resonant operation. Simulation results and experimental results are presented to verify the operating principles     

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