共查询到20条相似文献，搜索用时 31 毫秒
1.
Voltage source converter high-voltage direct current （VSC-HVDC） is a new power transmission technology pref- erable in small or medium power transmission. In this paper we discuss a new control system based on space vector modulation （SVM） without any voltage line sensors. Using direct power control （DPC） SVM and a new double synchronous reference frame phase-locked loop （DSRF-PLL） approach, the control system is resistant to the majority of line voltage disturbances. Also, the system response has accelerated by using a feed forward power decoupled loop. The operation of this control strategy was verified in a SIMULINK/MATLAB simulation environment. To validate this control system, a 5 kV.A prototype system was constructed. Compared to the original controllers, the current total harmonic distortion （THD）, the active and reactive deviations and the DC voltage overshoot were lowered by 2.5%, 6.2% and 8%, respectively. The rectifier power factor in the worst condition was 0.93 and the DC voltage settling time was 0.2 s. 相似文献
2.
This paper describes a prototype power delivery system developed for high voltage electronic current transformer (ECT) that uses laser light to transfer power to and communicates with the primary converter. The design is based on optical-to-electrical power converters, solid-state diode lasers and optical fibers. Command signals are transmitted via the same up-fiber used to send power from secondary power supply to primary converter. The upward data transmission is completed during the brief interruption of power delivery without affecting steady power-supply. A simple comparator added to the primary converter can take the command data. Experimental results show that the fibers can provide reliable up-link for data transmission at 200 kb/s from the secondary to the primary converter. Based on the delivery system, the secondary converter can control three auxiliary channels to provide additional information. These monitoring channels are used in a time-multiplexing mode to provide information about the operation temperature, voltage and current at the remote unit for monitoring the ECT. This preventive maintenance or built-in test can increase reliability by giving early warning for necessary maintenance request. 相似文献
3.
半导体激光器恒流驱动电路的研制 总被引：1，自引：0，他引：1
阐述了大功率半导体激光器恒流源的设计方法.该恒流源采用功率MOSFET作电流控制元件,运用负反馈原理稳定输出电流.应用结果表明该恒流源对激光器安全可靠,输出电流的短期稳定度达到1×10-5. 相似文献
4.
提出了一种两阶段多功能光伏逆变器(QMFI),有功功率借助于该结构可以在一个功率转换器内从光伏阵列直接传输到电网或负载,从而提高转换效率.此外,考虑QMFI最大功率点跟踪(MPPT)的实现和非有功电流的补偿,提出了QMFI的数学模型,从而获得有效的控制参数.在求解过程中,采用基于旋转坐标系的分析模型,并推导了QMFI的... 相似文献
5.
采用负电源纯模拟电路方案对掺铒光纤放大器(EDFA)泵浦电源的激光二极管(LD)的驱动电路和温度控制电路进行了设计,设计结果符合激光二极管驱动电源的工作要求. 相似文献
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7.
新型高精度数控恒流源的设计 总被引：2，自引：0，他引：2
针对传统数控恒流源恒流校正方法复杂、调整时间较长等缺点,利用PWM技术设计了一种新型的高精度数控恒流源.该恒流源以SoC单片机C8051F020为主控芯片,采用负反馈闭环控制的方法,由PWM信号实时调整输出设定的电流.测试结果表明,该恒流源在输出电流10mA-4A范围内,控制精度为1mA,电流输出值与设定值的相对误差小于0.1%,具有精度高、控制简单、响应快、自适应能力强等特点. 相似文献
8.
A diode-triggered silicon controlled rectifier （DTSCR） is being developed as an electrostatic discharge （ESD） protection device for low voltage applications. However, DTSCR leaks high current during normal operation due to the Darlington effect of the triggering-assist diode string. In this study, two types of diode string triggered SCRs are designed for low leakage consideration; the modified diode string and composite polysilicon diode string triggered SCRs （MDTSCR ＆ PDTSCR）. Compared with the conventional DTSCR （CDTSCR）, the MDTSCR has a much lower substrate leakage current with a relatively large silicon cost, and the PDTSCR has a much lower substrate leakage current with similar area and shows good leakage performance at a high temperature. Other DTSCR ESD properties are also investigated, especially regarding their layout, triggering voltage and failure current. 相似文献
9.
This work applied the ultrasonic bonding to package flip chip GaN-based light emitting diodes (flip chip LEDs) on Si substrates.
The effects of ultrasonic bonding parameters on the reliability of flip chip GaN-based LED were investigated. In the sequent
aging tests, samples were driven with a constant current of 80 mA for hundreds hours at the room temperature. It was found
that the electroluminescence (EL) intensity variation had a large correlation to the ultrasonic power, and then to the bonding
temperature and force. A high bonding temperature and ultrasonic power and a proper bonding force improved the EL intensity
significantly. It was contributed to a strong atom inter-diffusion forming a stable joint at the bonding interface. The temperature
fluctuation in the aging test was the main factor to generate a high inner stress forming delamination at the interface between
the chip and Au bump. As a result, delamination had retarded the photons to emit out of the LED packaging and decay its EL
intensity. 相似文献
10.
慢启动半导体激光器驱动电源的设计 总被引：2，自引：0，他引：2
根据半导体激光器的光功率与电流的关系,通过慢启动电路、纹波调零电路、功率稳恒电路等解决了使用中的电源在工作温度范围内其输出功率不稳定的问题。设计的电路稳定度达到4×10-4。 相似文献
11.
为解决便携式拉曼光谱仪进行定量分析时易受半导体激光器输出光功率以及波长稳定性影响问题,设计了一种基于 STM32 的高稳定度半导体激光器驱动电路系统。该系统采用高功率密度的恒流芯片 TPS54200为激光器提供稳定的恒流源,采用集成温度控制芯片 MAX1978 对激光器工作温度进行精确控制,结合主控芯片 STM32 对激光器输出光功率以及工作温度进行高精度调节和控制。实验结果表明,该系统对驱动电流 0~1500mA 可调,电流线性度为 0.17%|工作时间 1 小时内温度控制最大误差为 0.09℃|输出的峰值光波长偏差在0.02nm 以内|输出光功率范围宽,稳定性达到 0.08%。该设计满足光谱仪工作要求,系统稳定性较好,对同类型激光器适用性较强。 相似文献
12.
郑莹莹 《广东广播电视大学学报》2012,21(4):108-111
一种新型氦氖激光器电源以直流12V输入,并采用开关电源逆变、倍压整流等技术;摒弃了传统的大电阻恒流的方式,采用了负反馈电路控制电流,减少了功耗,且稳流精度高于2％;还增加了稳功率电路,稳功率精度可达3％以上。 相似文献
13.
In this paper, a 10 GHz radio over fiber system is analyzed. The Brillouin fiber-optic ring laser is used in the
center station (CS) to suppress the optical carrier for the modulation depth enhancement. Simultaneously, the Stockes wave
induced by the Brillouin amplification injects and locks the Fabry-Perot (FP) laser to output a signal-mode optical source,
which works as the uplink optical carrier. 相似文献
center station (CS) to suppress the optical carrier for the modulation depth enhancement. Simultaneously, the Stockes wave
induced by the Brillouin amplification injects and locks the Fabry-Perot (FP) laser to output a signal-mode optical source,
which works as the uplink optical carrier. 相似文献
14.
The magamp （magnetic amplifier） is widely used in power supplies due to its low cost, simplicity and other advantages. This paper discusses a novel application of the magamp in switching power supplies, where the magamp is used to regulate pulse width modulation （PWM） instead of power signal in the main circuit. This method extends the application of the magamp in power supplies, and makes it possible to further regulate control signal when PWMs have been generated. Based on this applica- tion, a new current-sharing （CS） scheme using the magamp is proposed, which uses a modified inner loop CS structure. In this scheme PWMs are generated by one main controller, and CS is achieved by regulating PWMs using a magamp in each module. Compared with traditional application of the magamp, the new CS scheme can be used in most topologies and only requires magamps of low power capacity. Then a test circuit of parallel power supply is developed, in which CS is achieved by a PWM regulator with the magamp. The proposed scheme is also used to upgrade an electroplate power to make it capable of paralleling supplies. Experimental results show that the proposed scheme has good CS performance. 相似文献
15.
有源电力滤波器（active power filter, APF）补偿电流跟踪控制要求具有较高的稳态精度和较快的动态响应速度。文章将自适应预测滤波算法应用于无差拍控制,实现APF补偿电流精确控制。根据APF时域数学模型,推导滤波系统的无差拍控制离散方程;通过自适应(finite impulse response filter, FIR)预测滤波算法实现基波电流预测,消除控制系统的计算延迟,给无差拍控制提供所需的指令电流预测值。对预测算法进行MATLAB仿真,验证预测算法的稳态精度和动态跟踪快速性;实验室样机验证控制实验结果证明所提出的控制策略有效的,具有一定的实用性。 相似文献
16.
本文首先基于三相静止坐标系的典型控制方案与基于d-q同步旋转坐标系的矢量控制方案作了比较,然后运用功率平衡的原理对本文给出的矢量控制方案进行了系统设计,并在此基础上提出一种前馈控制策略并进行了仿真验证。 相似文献
17.
A new PWM converter based on soft-switching is introduced.The converter uses a minimum number of devices,and requires less switching operations than conventional techniques,Switching is realized solely in a ZVS)zero voltage switching)mode,therefore the loss is reduced and EMI(electromagnetic interference)is suppressed.The paper analyzes the operation of ZVS,and discusses the methods for maintaining a unit power factor and constant DC voltage.Changing the modulation index M and the phase angle θ keeps the input current in phase with the voltage.It also keeps the current sinusoidal,and ensures a constant output voltage. 相似文献
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19.
Quasi-phase-matching(QPM) periodical poled LiNbO3 （PPLN） is designed and successfully fabricated to enable second harmonic generation (SHG),The samples were Z-cut 0.5 mm thick and grating period is A=6.8 μm for the first order QPM of contimual wave λ=1.064μm which is emitted by Nd:YAG laser at room temperature 27℃,The output single-pass SHG power was tested by an authorized optical system.The normalized max conversion efficiency is calculated to be 0.25% (W.cm)^-1,The fabrication and parameters calculated method are introduced,and testing scheme is described in this paper,Even some ideas to improve conversion efficiency are offered. 相似文献
20.
Calculating the current distribution in circular loop scatterers commonly involves complicated computation. In this paper,
based on the theory of Maxwellian circuits (MC), we propose a fast algorithm by solving a wave equation with constant parameters
corresponding to the circular loop. Our method prodeces similar results compared to the methods using method of moments (MoM)
with lower computational complexity. It is effective when there are parallel multiple circular loop scatterers. Experimental
results show accuracy of the method. 相似文献