一个易于系统集成的变步长反馈数字DC-DC变换模块

提出了一种采用单比较器变步长反馈控制和占空比抖动方法的数字DC-DC变换模块.它用6位二进制分辨率占空比的PWM信号实现了7位的电压分辨率.变步长反馈控制的使用使得它具有比恒定步长方案更好的动态性能,而且没有过多增加控制器的复杂度.在1MHz的开关频率下,控制器自身功耗小于0.5mW(不含功率开关及驱动部分).由于电路的模拟部分极少,因此易与数字系统进行单芯片集成.     

一种无需ADC的变步长反馈DC-DC 转换器数控方式

数控DC-DC变换器由于其自身的特点,易于与数字系统进行单片集成.DC-DC的数字控制算法有很多种,其中比较复杂的算法(如PID)需要在片内集成ADC,增加了设计难度.较为简单的控制方案只使用单一的比较器作为反馈输入部件,但动态性能较差.本文在已有的单比较器恒定步长反馈数控Buck转换器的基础上,提出了一类变步长反馈的方案.由于仍使用单比较器或窗口比较器,它的结构简单且易于集成.它借鉴了对分搜索的思路,能根据输出电压反馈的结果动态地改变占空比的变化步长,从而明显地提高了原有恒定步长反馈数控变换器的动态性能.     

模糊逻辑直接转矩控制的研究

本文提出了一种基于模糊逻辑的直接转矩控制方案,它由传统直接转矩控制部分选择出有效的开关电压状态,由模糊逻辑占空比控制器给出最优占空比,以完成相应的电压状态与零电压状态之间的调制,以此算法为基础设计了以数字信号处理器为核心的试验样机。并给出了实验结果。实验证明，该系统能够有效的减少直接转矩控制系统的转矩纹波，具有良好的动静态特性。     

一种新型移相谐振型开关控制器的研制

基于移相式全桥ZVS-PWM控制的原理和特点，对移相谐振控制IC的内部电路进行了分析。研制了一种新型的移相谐振开关控制器，它具有0～100%的占空比控制和1MHz的工作开关频率。     

一种电流反馈型三相无刷直流电机控制器

基于经典的闭环反馈控制理论和PWM理论在电机控制中的应用,设计了一种三相无刷直流电机控制器.该电路可实现对三相无刷直流电机的驱动和控制,具有功率电压高、驱动电流大、零点精确等优点,同时具有高边占空比100％可调和过流保护等功能,是一款真正的四象限扭矩电机控制器.     

双闭环反馈控制半桥DC-DC变换器设计

桥式拓扑广泛用于直流供电电压高于晶体管的安全耐压值的离线式变换器中,针对双闭环反馈控制半桥DC-DC变换器电路,为了得到稳定的直流电压、电流输出,采用电压闭环回路和电流闭环回路的反馈放大最终实现对半桥开关PWM波信号的控制,进而影响半桥变换器的轮流导通MOS开关管的导通占空比的方法,通过闭环网络仿真实验和硬件电路功率实验,验证了双闭环反馈控制可以满足半桥电路3.6 kW功率输出的要求.     

一种改进型太阳阵最大功率点跟踪方法

鉴于卫星上太阳阵使用的实际情况和现有太阳阵最大功率点跟踪理论,本文提出一种基于三点比较理论的改进型变步长控制方法,通过时占空比的简单控制,达到对最大功率点的快速跟踪逼近.它不但克服了常规控削方法存在的不足,而且对降低卫星生产和发射成本有着积极的意义.     

Ku波段GaN T/R一体多功能MMIC的研制

<正>首次研制了国内第一块Ku波段GaN T/R一体多功能全单片芯片,该芯片集成了T/R的接收通道和发射通道。接收通道含功率输出开关、前级低噪声放大器、5位数字衰减器、后级低噪声放大器、小信号开关和5位数字移相器;发射通道含5位数字移相器、小信号开关、驱动放大器、功率放大器和功率开关,如图1所示。在16~17 GHz工作频率内测得接收通道增益≥20±0.5 dB,噪声系数≤3.5 dB;发射通道增益约44 dB,饱和功率41 dBm(脉冲宽度100μs,10%占空比),功率附加效率约30%。在芯     

基于C8051F064单片机的高速数据采集与存储系统

利用C8051F064单片机实现数据采集与存储系统,它体积小,重量轻,性价比较高.介绍了单片机和其它相关器件的使用方法.说明了数字交叉开关、DMA控制器和ADC转换器的软件配置方法.分析了ADC转换器单端模式下对电压信号的采集过程和DMA控制器对外部存储器写入数据的过程.对数据采集的时间间隔进行了分析.数据采集与存储系统采样频率可以达到1Ms/s,并有16位A/D采样分辨率.介绍了如何利用两个相同系统级联的方法获得2Ms/s的采样频率.     

压缩感知相移数字全息术

相移数字全息图用传统数字再现可以消除零级像与共轭像,但数字全息术记录的全息图及数字再现像的分辨率被CCD的分辨率所限制.将新兴的压缩感知算法用于数字全息图的稀疏重建,以实现由部分全息图数据得到高分辨率再现像.分析了压缩感知用于重建数字相移全息图的原理,并利用该算法对计算机模拟的相移全息图进行了重建.结果表明,压缩感知算法能够对数字全息图稀疏重建,利用50％的部分全息图数据重建出了较高质量的再现像,并消除了零级像和共轭像.当选用合适的观测器如数字微反射镜器件或随机位相片实现随机观测矩阵时,可以实现单像素成像,从而突破记录全息图CCD分辨率的限制.     

基于有效占空比的ZVZCS全桥变换器建模与仿真

分析了零电压-零电流开关(ZVZCS)全桥脉宽调制(PWM)变换器的工作原理,引入变压器副边电压有效占空比的概念并考虑电路元件的寄生参数,在Buck变换器的PWM开关等效模型的基础上,建立了ZVZCS全桥软开关变换器的小信号等效模型,该方法通用于任何可以计算出有效占空比的全桥变换器.通过对小信号传递函数的幅频和相频特性...     

Measurement of Loop Gain with the Digital Modulator

A loop gain measurement technique for switching regulators using a digital modulator is introduced. While the conventional technique injects and measures the analog signals, the proposed digital modulator injects a digital perturbation and measures the resultant duty cycle modulation. Since the duty cycle signal, derived from all feedback loops, provides the ultimate control of a switching regulator, the loop gain defined at the duty cycle modulator is unique. Employing the digital modulator, this loop gain can be measured even with a switching regulator employing the current injected control. Furthermore, this new technique overcomes false measurement problems found in the conventional technique when the feedback signal at the point where the loop gain is measured contains a pulsating nature.     

Digital control of a voltage-mode synchronous buck converter

A digital control algorithm capable of separately specifying the desired output voltage and transient response for a synchronous buck converter operating in voltage mode was developed. This algorithm is based on superimposing a small control signal onto a voltage reference at each switching cycle to cancel out the perturbations. A zero steady-state error in the output voltage can be obtained with the aid of additional dynamics to allow the controller to track a load change and update the reference to a new load state. The specifications of the control algorithm are achieved by pole placement using complete state feedback. The control algorithm was implemented on a digital signal processor (DSP)-controlled synchronous buck converter.     

Single switch dual output DC-DC converter performance

The performance of the single-switch dual-output DC-DC converter is evaluated. This converter regulates two independent DC outputs supplied from a single DC voltage source using a power semiconductor switch. Two discrete proportional feedback control loops regulate the duration of on switching and off switching. The duty cycle of the switch controls one output voltage, supplied from a low-pass filter, while the switching frequency regulates the other output voltage, supplied from a higher-frequency bandpass filter. The control algorithm is implemented with an Intel 8096 microcontroller. The experimental data demonstrate the actual circuit performance and confirm the simulation results. Both experiments and simulation show that an increase in the load current on the 12 V output results in an increase in the duty cycle, whereas an increase in the load current on the 5 V output results in a change in the switching frequency. The experimental prototype demonstrates operation over a load current range from about 40% to 100% with a ±25% variation in the 24 V input. Full load currents are 12 A and 2.5 A on the 12 V and 5 V outputs, respectively. The switching frequency ranged from approximately 29 kHz to 264 kHz, and the duty cycle ranged from 0.35 to 0.72     

Frequency tunable low ripple and fast response on-chip DC–DC converter for DVFS

Dynamic voltage and frequency scaling (DVFS) is an efficient method to reduce the power consumption in system on-chip. To support DVFS, multiple supply voltages are generated based on different work load frequencies and currents using on-chip DC–DC voltage converter. In this paper a frequency tunable multiple output voltage switched capacitor based dc–dc converter is presented. An analog to digital converter and phase controller is used in the feedback to change the switching frequency and duty cycle of the converter. An input voltage of 1.8 V is converted to 0.6 and 0.8 V for low and high signal frequency respectively. The proposed 2-phase switched capacitor architecture with gain setting of 1:2 is designed with the 90 nm technology. An output ripple of 45 mV is observed and the maximum transient response time of the converter is 17.3 ns (= 58 MHz).     

Limit-Cycle Oscillations Based Auto-Tuning System for Digitally Controlled DC–DC Power Supplies

This paper introduces a new method and system for parameter extraction and automated controller adjustment, suitable for low power digitally controlled DC-DC switch-mode power supplies (SMPS). The system allows closed-loop calibration throughout regular converter operation. During a short-lasting test phase, SMPS parameters, such as output capacitance and load, are estimated by examining the amplitude and frequency of intentionally introduced limit cycle oscillations in duty ratio control variable as well as from its steady state value. Accordingly, a digital compensator is automatically constructed to provide fast dynamic response and good output voltage regulation. In addition, the load estimation data are used for improving efficiency of a converter having segmented transistors. It is performed through a selection of driving sequence resulting in minimized sum of switching and conduction losses. The effectiveness of the system is demonstrated on an experimental 400 kHz, 9 V-to-3.3 V, 10 W, digitally controlled synchronous buck converter.     

Optimized piezoelectric energy harvesting circuit using step-down converter in discontinuous conduction mode

An optimized method of harvesting vibrational energy with a piezoelectric element using a step-down DC-DC converter is presented. In this configuration, the converter regulates the power flow from the piezoelectric element to the desired electronic load. Analysis of the converter in discontinuous current conduction mode results in an expression for the duty cycle-power relationship. Using parameters of the mechanical system, the piezoelectric element, and the converter; the "optimal" duty cycle can be determined where the harvested power is maximized for the level of mechanical excitation. It is shown that, as the magnitude of the mechanical excitation increases, the optimal duty cycle becomes essentially constant, greatly simplifying the control of the step-down converter. The expression is validated with experimental data showing that the optimal duty cycle can be accurately determined and maximum energy harvesting attained. A circuit is proposed which implements this relationship, and experimental results show that the converter increases the harvested power by approximately 325%.     

A new algorithm for rapid tracking of approximate maximum power point in photovoltaic systems

This paper presents a new algorithm for tracking maximum power point in photovoltaic systems. This is a fast tracking algorithm, where an initial approximation of maximum power point is (MPP) quickly achieved using a variable step-size. Subsequently, the exact maximum power point can be targeted using any conventional method like the hill-climbing or incremental conductance method. Thus, the drawback of a fixed small step-size over the entire tracking range is removed, resulting in reduced number of iterations and much faster tracking compared to conventional methods. The strength of the algorithm comes from the fact that instead of tracking power, which does not have a one-to-one relationship with duty cycle, it tracks an intermediate variable /spl beta/, which has a monotonically increasing, one-to-one relationship. The algorithm has been verified on a photovoltaic system modeled in Matlab-Simulink software. The algorithm significantly improves the efficiency during the tracking phase as compared to a conventional algorithm. It is especially suitable for fast changing environmental conditions. The proposed algorithm can be implemented on any fast controller such as the digital signal processor. All the details of this study are presented.     

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.