Integrated optical high-voltage sensor based on a polymeric Y-branch digital optical switch

An integrated optical high-voltage sensor is realized by fabricating a Y-branch digital optical switch in an electrooptic polymer. The measurement of ac high voltage is accomplished by using the linear transfer characteristics of the switch at zero bias voltage. Furthermore, the logarithmic ratio between the optical powers of two output ports may be used to remove the noise caused by the power fluctuations of a light source. The polymeric high-voltage sensor requires no electrical dc biases and no voltage dividers. It is also wavelength insensitive and fabrication-tolerant due to its use of mode evolution effects instead of interference. The measured sensing voltage range is as large as ac 500-V peak-to-peak.     

利用单块硅酸铋晶体同时测量交流电压和电流

设计并实验实现了利用单块硅酸铋(Bi12SiO20,BSO)晶体同时测量交流电压和电流的传感方案,其光学传感单元仅由起偏器、BSO 晶体和检偏器组成。BSO 晶体兼有Pockels 电光效应和Faraday磁光效应,在起偏器和检偏器的主透光方向互相平行或互相垂直的情况下,输出光信号中同时包含被测电压和电流传感信号,其中电压传感信号为被测电压的倍频信号,而电流传感信号则与被测电流同频率,因而可以利用电子滤波器从光电检测信号中分离出电压与电流传感信号,从而实现电压和电流的同时测量。利用一块尺寸为6.04.02.9 mm3 的BSO 晶体,实验实现了6 A、200 V 范围内工频电流与电压的同时测量。     

Small AC Driving Voltage for MZI-Based GaAs–GaAlAs Electrooptic Modulators/Switches With Coplanar Electrodes

We report a method to achieve a small ac driving voltage for high-speed multimode interference Mach-Zehnder interferometer GaAs-GaAlAs electrooptic modulators and switches with coplanar electrodes for polarization-insensitive operation. By biasing the devices in the reverse break-down region, the ac driving voltage can be as small as 3 V. Such a small ac driving voltage is important for high-speed optical modulators and switches. The physics behind this small ac driving voltage is also discussed.     

利用计时器芯片和脉冲占空比调制的光电式电压传感器

提出一种利用计时器芯片和脉冲占空比调制的光 电式电压传感器,用于测量直流高电压。利用计时 器芯片ICM7555,可以将被测直流高电压转换为脉冲占空比调制信号, 并驱动发光二极管(LED)产生脉冲光 传感信号;利用单根多模塑料光纤将光传感信号传输到光电探测器及信号处理电路,即可获 得光电传感信 号,通过测量其脉冲占空比,即可解调出被测高电压。分别采用输出脉冲频率和脉冲占空比 作为电压传感 信号,实验测量了10 kV直流高电压,并比较分析了测量结果的相对 误差。结果表明,采用输出脉冲占空 比作为电压传感信号时,传感器的相对误差更小,此时测量结果的引用误差低于0. 6%。     

Analysis and Demonstration of Mach–Zehnder Polymer Modulators Using In-Plane Coplanar Waveguide Structure

Analysis, design, and experimental demonstration of polymer Mach-Zehnder (MZ) modulators with a newly proposed in-plane coplanar waveguide (CPW) electrode are presented in this paper. Compared to the conventional CPW electrode, the new in-plane CPW configuration significantly enhances the overlap factor between microwave and optical wave by 40% from the theoretical calculations. Different from polymer modulators using the traditional microstrip electrodes, this structure can suppress dc bias voltage drift and widen modulation bandwidth. Using CLD1/APC and AJL8/APC electrooptic polymers, MZ modulators using the in-plane CPW are fabricated and tested. The measured Vpi's of the MZ with 15-mum gap spacing and 2 cm electrode length are 5.4 and 9.5 V at 1.55 mum for the AJL8/APC and CLD1/APC devices, respectively. The evaluated Upsi₃₃'s are 46 pm/V for the AJL8/APC and 26 pm/V for the CLD1/APC MZ. The dc bias stability is tested and compared for both the microstrip and the in-plane CPW electrode modulators. Experimental results show that the in-plane CPW modulator greatly improves the bias stability. From the microwave measurement, the microwave signal loss of the modulator using the in-plane CPW is much reduced to 0.2 dB/cmradicGHz, while 0.7 dB/cmradicGHz using the microstrip.     

Optical fiber current sensors in high electric field environments

This paper analyzes the response of optical fiber current sensors that are subjected to high electric fields, such as fields encountered in gas-insulated systems. This paper shows that through the electrooptic (EO) Kerr effect, these fields can cause harmonic distortion of the measured ac current waveform. This harmonic distortion was confirmed experimentally. Also, this paper shows that it is possible to simultaneously measure both current and voltage waveforms and the phase between them using this effect. To minimize the electrooptic Kerr effect, optical fiber current sensors must be screened from high-electric fields     

铌酸锂双面金属包覆波导电压传感特性

设计了一种利用铌酸锂作为波导基片的双面金属包覆平板光波导,利用波导中超高阶导模高敏感特性制成了一种反射型光学电压传感器。入射激光束采用小角度入射,当光波导处于导模共振状态时,选择一个恰当的工作点,再通过两金属电极对该器件施加直流电压,通过检测反射光强,获得相应的电压值变化。实验测量中所用的电压范围是-800～800V, 得到的线性度值为0.995,波导反射光的反射率变化灵敏度为0.2V-1,实验表明这种电压传感器具有较好的线性和灵敏度,该新型电压传感器具有结构与制作简单、调节方便和成本低廉等优点。     

Flexible and low cost design for a flyback AC/DC converter with harmonic current correction

This study presents a new simple flyback ac/dc converter with harmonic current correction and fast output voltage regulation. In the proposed ac/dc converter, an extra winding wound in the transformer provides two key advantages. The size of the bulk inductor used in the conventional boost-based power factor correction cell can be significantly reduced in the proposed converter. The voltage across bulk capacitor can be held under 450V by tuning the transformer winding ratio even though the converter operates in a wide range of input voltages (90 V/spl sim/265V/ac). This new converter complies with IEC 61000-3-2 under the load range of 200 W, and can achieve fast output voltage regulation.     

Single-Stage AC/DC Converter With Input-Current Dead-Zone Control for Wide Input Voltage Ranges

A single-phase single-stage ac/dc converter with input-current dead-zone control is proposed. It is based on flyback topology operating in discontinuous conduction mode (DCM). The current charging into the link capacitor is controlled according to line changes by adjusting the input-current blocking angle to alleviate an excessive increase of the link voltage. The reduced voltage stress can maintain an almost-constant voltage irrespective of load conditions by operating in dc/dc stage in DCM. Experimental results of a 60-W (5-V 12-A output) prototype converter show that the link voltage is limited within 384 V and that the measured power factor is more than 0.91 under universal voltage inputs and entire load conditions. In addition, the maximum efficiency is measured to be about 81% at the rated condition     

BGO晶体固有线性双折射及其温度特性的定量研究

BGO晶体的固有线性双折射及其温度特性严重制约着光学电压互感器(OVT)的实用化进程,对其进行定量研究有助于提高和改进OVT的性能。文中提出了一种晶体劈干涉条纹图像法,通过测量干涉条纹的移动实现对BGO晶体内部固有线性双折射及其温度特性的准确测量。文中采用琼斯矩阵对测量原理进行了推导,并给出了测量实例和验证结果。结果表明,单位长度的BGO晶体固有线性双折射会给OVT带来约1.0%的测量误差;考虑温度特性,误差约为1.2%,对于OVT必须具备0.2%的测量准确度是一个严重挑战。文中提出的方法与传统的光强法比较,不受光源功率波动的影响,在测量过程中无需调节光学元件,不会引入额外的误差,测量准确度提高了约一个数量级。     

Photonic Polarity-Switchable Ultra-Wideband Pulse Generation Using a Tunable Sagnac Interferometer Comb Filter

A photonic approach to polarity-switchable ultra-wideband (UWB) pulse generation is proposed. The proposed setup principally consists of an electrooptic phase modulator (EOPM) and a tunable optical comb filter constructed with another EOPM inside a Sagnac interferometer. The comb filter working at its linear region performs the phase-to-intensity conversion to generate UWB pulses with monocycle shape. By adjusting the bias voltage of the EOPM inside the Sagnac interferometer, a shift of the comb filter can be achieved, which is the key point for a pulse polarity switch. A pair of monocycle pulses with reversed polarities was experimentally obtained by applying the dc bias of 0 and 1.9 V, respectively. The convenience to electrically control the pulse polarity is favorable for biphase modulation in UWB impulse radio applications.     

Electrooptic ferroelectric Na/sub 0.5/K/sub 0.5/NbO/sub 3/ films

We report on waveguiding and electrooptic properties of epitaxial Na/sub 0.5/K/sub 0.5/NbO/sub 3/ films grown by radio-frequency magnetron sputtering on Al/sub 2/O/sub 3/(11_02) single crystal substrates. High optical waveguiding performance has been demonstrated in infrared and visible light. The in-plane electrooptic effect has been recorded in transmission using a transverse geometry. At dc fields, the effective linear electrooptic coefficient was determined to 28 pm/V, which is promising for modulator applications.     

New single-stage low dc bus voltage stress converter for universal line applications

A new single-stage power factor corrected ac–dc converter for universal line applications is proposed in this paper. This converter has a buck topology as a power factor corrector. The dc bus voltage of the proposed converter is always lower than the peak input voltage at any load condition. Therefore, the problem of high dc bus voltage under the light load condition for the single-stage converter is solved, especially in the case of universal line applications. The design equations are presented for the proposed converter and a design example for a 5V 12A application is presented. The theoretical analysis and experimental results show that the dc bus voltage can be limited within 260V and the line input current harmonics can meet IEC 61000-3-2 Class D requirements at any load conditions for the line input voltages from 90 to 260V_ac.     

Optical High DC Voltage Sensor Based on White-Light Interferometry

This letter reports an optical system for high dc voltage measurement utilizing a bulk$hboxLiNbO_3$crystal with specialized-orientation as a sensing element. White-light interferometry is employed to encode the electric voltage information in the optical spectrum instead of intensity. Measurement of dc voltage from 0 to 9 kV with resolution of 2.3 V has been experimentally demonstrated.     

Proposed electrooptical PCM multiplexer-demultiplexer

A reciprocal time multiplexer-demultiplexer for optical PCM is proposed. The device is based on the coincidence of an optical pulse and a modulating voltage pulse in an electrooptic crystal. Both a lumped and a traveling-wave configuration are described.     

Electrooptic temperature sensor based on a Fabry-Pe/spl acute/rot resonator with a liquid crystal film

An electrooptic (EO) temperature sensor based on a Fabry-Pe/spl acute/rot (FP) resonator with a nematic liquid crystal (NLC) film is proposed. A novel compensation scheme of the EO effect allows for precise determination of temperature by monitoring the resonant wavelength of the NLC FP sensor. The proposed EO temperature sensor provides good stability, high resolution, self-calibration capability, and low driving voltage.     

Hybrid Integrated Cascaded 2-bit Electrooptic Digital Optical Switches (DOSs)

Hybrid integrated cascaded 1 times 4 electrooptic (EO) polymeric digital optical switches (DOSs) are proposed and demonstrated. The hybrid integration of passive polymer on the same chip with EO polymer can lower the overall device loss without affecting the EO effects. The cascaded DOS can be controlled by only two voltage signal sources without bias stabling mechanism. The device can be operated as a 2-bit reconfigurable switch. The switching voltage is around 15 V for single arm driving with reasonable extinction ratio (9~12 dB) and the loss is improved by ~2.5 dB. This device is ideal for implementing variable optical delay network     

A new power converter for fuel cells with high system efficiency

This paper presents a new high-efficiency grid-connected single-phase converter for fuel cells. It consists of a two-stage power conversion topology. Since the fuel cell operates with a low voltage in a wide voltage range (25?V–45?V) this voltage must be transformed to around 350–400?V in order to be able to invert this dc power into ac power to the grid. The proposed converter consists of an isolated dc–dc converter cascaded with a single-phase H-bridge inverter. The dc–dc converter is a current-fed push-pull converter. The inverter is controlled as a standard single-phase power factor controller with resistor emulation at the output. Experimental results of converter efficiency, grid performance and fuel cell dynamic response are shown for a 1?kW prototype. The proposed converter exhibits a high efficiency in a wide power range (higher than 92%) and the inverter operates with a near-unity power factor and a low current THD.     

Amplitude distortion compensation for voltage source dc/ac inverters

The objective of this paper is to propose two different modified sinusoidal pulse width modulation (SPWM) control schemes, MPWM-S and MPWM-T, for the dc/ac inverter with a non-constant dc voltage source. The amplitude distortion of the pulse width modulated waveforms is caused by the input dc voltage source variation and has the most significant impact on the dc/ac inverter’s ac output voltage spectral errors. The proposed MPWM-S and MPWM-T can achieve the desired fundamental amplitude and eliminate the low order harmonic components caused by the dc voltage source variation. The mathematical analysis of the amplitude distortion and the systematic development of the MPWM-S and MPWM-T are presented in this paper. The proposed MPWM-S and MPWM-T are feed-forward compensation methodologies and can be integrated with any practical feedback control schemes. Hardware implementations of the proposed control schemes can be easily accomplished by adding one or two analog multipliers to the traditional SPWM control circuit. The performance of the two proposed modified SPWM control schemes is verified by experimental results.     

A mechanically biased electrooptic polymer modulator

Mechanical biasing of an electrooptic polymer modulator is proposed and demonstrated by heterogeneously integrating waveguide structures with a piezoelectric element. Biasing is achieved by changing the path-length of one arms of a Mach-Zehnder interferometer by mechanically bending the waveguide structure. Applying ac voltage to the piezoelectric element generates a pilot tone, which is used to monitor the bias point of the modulator, while applying dc tunes the modulator to quadrature. The method separates the biasing and RF modulation of the device, thus avoiding the need for external biasing components and eliminating electrical bias drift