一种宽恒流范围数字控制LED驱动电路

为提高发光二极管(LED)驱动电路恒流稳定性,设计一种基于原边反馈反激变换器的数字恒流源作为驱动电路。采用数字软启动电路消除浪涌电流,避免了输出电压过冲。软开关技术的应用使得系统在整个恒流范围内的平均效率高达80.49%。逐周期的峰值电流控制实现了恒流输出。基于SMIC 0.18 μm CMOS工艺进行物理设计,版图面积为14 370 μm²。仿真结果表明,该LED驱动电路可根据用户需求,通过调整电路参数,在提高输出电流稳定性的基础上实现400~1 000 mA的恒流输出,输出电流纹波仅为0.28%。     

一种原边控制恒流LED驱动电路设计

提出了一种应用于LED照明的原边控制电路,通过控制变压器初级峰值电流与tDIS/TS(占空比)的乘积为一个常数,从而实现平均输出电流恒流;通过检测电压谷底来开启原边功率管,大大减小了导通开关损耗。仿真结果表明,该电路成功实现了平均输出电流的恒流控制,效率为93.3%,说明驱动反激变换器工作在准谐振模式有较高的转换效率。     

一种基于原边反馈控制的LED恒流驱动芯片

基于原边反馈控制技术,提出了一种具有功率因数校正功能的反激LED恒流驱动控制芯片。分析了原边反馈控制的反激LED驱动电路的原理,提出一种新颖、结构简单的恒流控制电路,提高了输出恒流精度。采用谐振谷底开通的开关方式,降低了功率MOS管的开关损耗。该LED驱动芯片基于CSMC 1 μm 40 V BCD工艺设计。仿真结果表明,在90~270 V输入范围内,该LED驱动电路的功率因数大于0.98,输出电流误差小于0.5%。     

NCL30081：3．6W反激式阶梯可调光LED设计方案

0nSemi公司的NCL30081是一款定他任隔离反激式拓扑和非隔离恒流拓扑的PWM电流模式控制器。该控制器采用准谐振模式提供高效率,这种新颖的控制方法可以从原边精确控制输出恒定LED电流,该控制输出通过副边反馈电路系统、偏置电路和一个光耦合器实现。     

蝶形半导体激光器恒流驱动设计与实现

蝶形半导体激光器驱动电流的稳定性直接决定了其输出波长的稳定性,进而影响检测精度。为了满足气体浓度检测中对激光器输出波长稳定可调的要求,设计了数字与模拟电路混合的恒流驱动电路。以STC90C51为主控芯片数控模块完成扫描键盘、DA转换;模拟电路主要由负反馈运算放大、高精度CMOS管和反馈电阻构成,完成电压到电流的转换,输出至蝶形半导体激光器,实现蝶形半导体激光器恒流驱动。输出电流在0~300 mA范围内连续可调,输出驱动电流误差小于±0.003 mA,满足系统对恒流驱动±0.005 mA的误差精度要求。     

一种原边控制的小功率反激式LED恒流驱动电路

介绍了一种具有功率因数校正功能的原边反激式LED驱动变换器。分析了原边控制的反激式变换器恒流输出的原理与输出电流线性调整率衰退的主要原因;设计了一种自适应的片内功率管关断延时检测与补偿电路,改善了输出电流的线性调整率。设计的单级反激式变换器在90~260 V交流输入电压范围内,功率因数大于0.9,输出功率范围为5~13 W。通过采用改进的峰值电流采样技术与内置自适应关断延时补偿技术,输出电流的线性调整率由23.3%减小到小于1.2%。     

LLC谐振半桥DC-DC电路设计

LED驱动电源的后级DC-DC恒流电路采用LLC谐振半桥的拓扑结构,并通过输出的电流电压双环反馈来实现恒流限压功能。LLC谐振半桥DC-DC恒流电路的功率部分包括了谐振电路和输出整流电路,控制部分有芯片供电电路、控制芯片外围电路、输出反馈回路等,经试验证明该系统输出稳定好,能够长时间高效工作。     

一种新型原边反馈反激式数字控制LED驱动电源设计

设计了一种采用新型数字控制方法的原边反馈反激式LED恒流驱动电源。该电源电路运用拐点检测法测量副边电路放电时间,运用增量式PID算法调节恒流和功率因数,实现对电路的精确恒流控制和保持较高的功率因数。通过分析其控制原理,给出设计流程,最终基于FPGA实现控制,进行了样机设计和算法验证。实验结果表明所提出电路全工作范围内恒流精度达到6%,功率因数高于0.97,整机效率超过80%。本电路结构简单,控制精度高,具有较高的实用价值。     

采用自适应滞环控制的LED恒流驱动芯片

设计了一种降压型LED恒流驱动芯片。该芯片采用电流滞环控制技术对输出电流进行恒流控制,实现输出高达2 MHz的开关频率。通过比较外部反馈电阻上的压降与芯片内部的滞环电压,使输出电流的波形为滞环变化三角波。采用了全新的自适应滞环电压产生电路,以补偿芯片内部的延时,实现了在2 MHz的开关频率下小于3%的恒流精度。该LED恒流驱动芯片采用ASMC 0.35 μm 5 V/60 V BCD工艺,工作电源电压范围为5~60 V,最高工作频率为2 MHz,典型平均输出电流为700 mA。该芯片具有PWM调光功能,通过DIM信号的占空比来调节LED的亮度。     

用于原边反馈反激变换器的电压采样电路设计

设计了一种用于原边反馈反激变换器的电压采样电路,该电路利用一个具有正温度系数的电流去补偿输出整流二极管正向压降的负温度系数,以消除由二极管正向压降的温度系数导致的误差和系统的误操作,电路具有过零检测功能,能够检测次边二极管电流的过零位置,减小由二极管正向压降引起的误差。本电路采用0.5μm BiCMOS工艺,利用Hspice对电路进行仿真。结果表明,本电路能够有效抵消整流二极管80%的温度系数值并准确检测次边电流零点,提高采样精度。     

大功率电弧加热器电源的设计研究

研究了63MW等级的大功率电弧加热器交直流电源的主电路设计和控制策略。提出了一种相移叠桥组合晶闸管整流主电路结构,使得该电源输出直流电压从1kV到21kV的不同工况时,其输入端的功率因数不小于0.9,且高功率时THD小于5%。根据主电路相移叠桥结构的特点,提出了一种非线性反馈控制器和前馈控制器相结合的复合稳流控制策略,稳流精度能够达到0.1%。实验结果表明,相移叠桥组合晶闸管主电路结构达到了电源电能质量设计指标;采用复合稳流控制策略后,稳流精度不仅能够达到设计指标,而且可以去掉主电路中的稳流电阻,从而减小了电源系统1.8MW的电阻热耗。     

A new state feedback based transient control of PWM AC to DCvoltage type converters

This paper presents a new state feedback based control strategy for a PWM AC to DC voltage type converter with phase and amplitude control. In this control strategy the state variables of the LC filter connected to the AC side of the converter are fed back to the PWM pattern generator, thereby eliminating a DC offset of the AC input currents as well as oscillations of the DC output current during transients. Computer simulation of the converter system with the proposed control strategy shows that the transient waveforms of AC input and DC output currents are improved greatly even if the damping effect of the AC side resistance can not be expected. The DC voltage regulation with good dynamic response is also achieved even if DC capacitance is substantially reduced. Experimental results from a low power laboratory model are also included to confirm the simulated results and to demonstrate the effectiveness of the proposed control strategy     

基于注入电流扰动法的光伏直流模块的防孤岛控制

传统的交流型并网发电系统中,可以通过检测电网电压或频率,采用有功扰动、无功扰动或频率扰动等方法实现防孤岛控制。而在共直流母线系统中,母线直流电压是唯一可检测的变量,因此传统的防孤岛控制策略无法适用。以共直流母线分布式系统中光伏直流模块的防孤岛控制为研究对象,建立了模块正常运行和孤岛运行时的数学模型,推导得到了在两种工况下模块输出电压的时域表达式,并在此基础上提出了一种基于注入电流扰动法的新型防孤岛控制策略。该控制策略的核心思路是通过控制模块输出电流和扰动步长来改变在扰动时间内模块的输出电压特性,并根据检测判据来决策是否发生孤岛。最后,本文以Boost+FB-LLC的两级式结构作为光伏直流模块的工作拓扑,并设计了一台1000W的实验样机,样机实验结果验证了本文所提出的防孤岛控制策略的有效性。     

A single-switch AC/DC converter with voltage regulated storage capacitor

A single-stage power-factor-corrected AC/DC converter (SSPFC) usually causes high voltage stress on the intermediate storage capacitor, due to the lack of control of this voltage. The storage capacitor voltage varies largely with line voltage, and load current and is usually higher than the peak line voltage. This paper presents a new single-switch SSPFC based on a flyback topology for which the storage capacitor voltage is loosely regulated by the output voltage. Without using extra power switches to increase the control dimension, the proposed converter uses a flyback converter with dual-output transformer to achieve the control purpose. The range of storage capacitor voltage change against the change of input voltage and load current is significantly reduced. Moreover, the maximum storage capacitor voltage can stay below the peak line voltage at high line condition. Experimental results verifying the operation of the proposed SSPFC are also reported.     

Adaptive current-threshold detector for an adaptive on-time Buck converter at light load

The adaptive on-time control technique has been tremendously utilized in DC–DC converters for its fast transient response, easier design and high efficiency at light load. In some applications the output voltage ripple of DC–DC converters has to be maintained within an acceptable level to achieve superior performance, which depends largely on the load current for adaptive on-time buck converters when operating in discontinuous conduction mode. This paper proposes an adaptive current-threshold detection method for reducing the output voltage ripple. An actual detector circuit is presented to implement the method. This circuit monitors the relationship between the peak inductor current and the load current at light load. Then it outputs a logic signal which controls the turn-on time of the main power MOSFET and hence the peak inductor current. Therefore, the magnitude of the output voltage ripple is controlled. The current-threshold detection method has been verified in an adaptive on-time buck converter by simulation and experimental results. The proposed method can also be used in other constant on-time converters.     

Quasi current resonant DC link AC/AC converter

A new quasi current resonant DC link (QCRDCL) topology has been developed in this paper. Although prototype current resonant DC link topologies for AC/AC power conversion have had such problems as irregular high current peaks, uncontrollable pulse width, etc., this new topology enables the AC/AC conversion system to have the properties wherein the current peak is limited and the pulse width is adjustable. The system begins to assume an adjustable-width flat-topped current shape, whereby the system becomes particularly suitable for high power application. With control of the pulse width a very fine load current regulation can be obtained. In this system, an open loop PWM control has been adopted and almost the same quality of output waveforms as the conventional current source inverter has been achieved     

电压不平衡时基于改进无差拍控制的VSC-HVDC系统

VSC-HVDC在电网电压不平衡情况下,输出功率及直流母线电压会产生二倍频波动,进而影响系统的稳定运行。文中研究了柔性直流输电系统在电压不平衡情况下的改进无差拍控制策略,该策略以瞬时有功功率波动分量为零为约束条件,推导了正负序参考电流表达式。针对传统无差拍控制算法存在的控制延时及对交流侧电感参数变化鲁棒性差的问题,提出了一种改进无差拍控制策略。该控制策略利用拉格朗日插值法预测出下一个采样时刻的参考电流;对电网电压进行了线性预测;对网侧电流进行了非线性预测。最后借助MATLAB/Simulink平台搭建相应的仿真模型,仿真结果证明了该控制策略的正确性和有效性。     

高精度激光器电流驱动与交流温控系统设计

半导体激光器作为原子磁强计的重要组成部分,其波长和功率主要由电流和温度决定,而传统的直流温控系统会对磁强计产生磁场干扰。针对高精度电流控制、温度控制和磁场干扰问题,设计了一种激光器恒流源驱动和交流控温系统。首先,设计基于功放的高精度激光器恒流源驱动系统;然后,设计交流温度调制解调检测和交流加热驱动系统;最后,采用STM32控制器、高精度AD采集和DA输出结合温度模糊自适应PID控制算法进行高精度温度控制。实验结果表明:在42℃温度下控制精度为0.005℃,在32 mA电流下稳定度为0.5 A,为激光器光功率和波长稳定性奠定基础。     

Linearly controllable boost voltages from Tri-Level PWMcurrent-source inverter

The peak line-to-line inverter AC voltage, in general, cannot exceed the supply DC voltage and transformers have to be used when voltage step-up is required. This paper describes how the necessity of using a Tri-Level PWM strategy in the current source inverter can be turned into an advantage by producing a voltage boost so that transformers are no longer required. During the frequent occurrence of the “shoot-through” states, which is the characteristic of the Tri-Level PWM-controlled inverter, magnetic energy builds up in the DC link inductor. At the end of these periods, the L_dcdI_dc/dt voltage across the inductor augments the inverter output voltage in the same way as in the basic boost type DC/DC power converter. The paper describes the circuitry required to ensure linear control. Analytical, simulation, and experimental results are given. Applications are found in all instances where the AC voltage is higher than the available supply DC voltage