A constant output current three-phase diode bridge rectifier employing a novel "Electronic Smoothing Inductor"

This paper presents an improvement of the well-known conventional three-phase diode bridge rectifier with dc output capacitor. The proposed circuit increases the power factor (PF) at the ac input and reduces the ripple current stress on the smoothing capacitor. The basic concept is the arrangement of an active voltage source between the output of the diode bridge and the smoothing capacitor which is controlled in a way that it emulates an ideal smoothing inductor. With this the input currents of the diode bridge which usually show high peak amplitudes are converted into a 120/spl deg/ rectangular shape which ideally results in a total PF of 0.955. The active voltage source mentioned before is realized by a low-voltage switch-mode converter stage of small power rating as compared to the output power of the rectifier. Starting with a brief discussion of basic three-phase rectifier techniques and of the drawbacks of three-phase diode bridge rectifiers with capacitive smoothing, the concept of the proposed active smoothing is described and the stationary operation is analyzed. Furthermore, control concepts as well as design considerations and analyses of the dynamic systems behavior are given. Finally, measurements taken from a laboratory model are presented.     

Application of genetic algorithm to sample balance analysis ofnonlinear circuits

A genetic algorithm has been applied for the first time to the sample balance method for nonlinear circuit analysis. Results for a circuit containing an ideal diode show this to be a viable approach which does not suffer from the limitations of other techniques for solving sample balance and harmonic balance equations. The algorithm does not require a good initial estimate nor does it need a Jacobian formulation of the circuit equations     

10 MHz CMOS OTA-C voltage-controlled quadrature oscillator

A quadrature-type voltage-controlled oscillator with operational transconductance amplifiers and capacitors (OTA-C) is presented. A monolithic integrated CMOS test circuit is introduced to verify theoretical results. The attainable frequency range of oscillation of the chip test circuit is 3-10.34 MHz. The total harmonic distortion (THD) is 0.20-1.87% for corresponding peak-to-peak amplitude voltages between 100 mV and 1 V. This amplitude can be controlled either by using a diode connection of two MOS transistors or a proposed nonlinear resistor.<>     

1.9 GHz low loss varactor diode pre-distorter

Pre-distorters implemented at circuit level using series diodes have a high loss. The method presented here combines source/load second harmonic control with a parallel connected varactor diode. A reduction of 15 dB in the spectral regrowth at 1.9 GHz is achieved with a low loss of 2 dB due to the varactor diode     

Investigation of Intermodulation in a Tuning Varactor

2nd and 3rd order intermodulation distortions of a tuning varactor are analyzed by using nonlinear parameters P2 and ￠3 which are determined by the measured values of the diode capacitance. The calculated values by using ￠agree quite well with the experimental results for actual diodes. In addition, the methods of compensating the distortion by a fixed capacitor or another diode with appropriately divided bias voltage are discussed and it is shown that the nonlinearity is compensated even in the case of n greater than 0.5. These methods are particularly effective for a circuit with greater Q.     

A Novel Circuit Architecture for High Performance of High-order Subharmonic Mixers

A novel circuit architecture for high performance of high-order subharmonic (SH) mixers is proposed in this paper. According to the specified harmonic mixing order, one or more mixer diodes sub-arrays and corresponding power divider as well as phase shift network for RF and LO signals are arranged in the circuit. This proposed SH mixer circuit has improved conversion loss, wide dynamic range and high port isolation for high-order SH mixers. By phase cancellation of idle frequencies, the proposed SH mixer circuit can eliminate complicated design procedure of idle frequency circuits; by phase cancellation of leakage LO power to RF and IF port, and leakage RF power to LO port, the mixer circuit can get high port isolation in LO-IF/RF and RF-LO. The increased antiparallel diode pairs in each sub-array will also lead to well performance by lowering effective series resistance. The proposed SH mixer circuit can be easily realized with power divider and phase shift network for RF and LO signals.     

An exact analysis of a parametric subharmonic oscillator

An analysis of a subharmonic oscillator using an ideal nonlinear capacitor is given in which the variables are so chosen that the problem reduces to a set of linear equations. The resulting solutions are exact, but multivalued, and the choice of the correct one is made as a result of experiments using a step-recovery diode. The method of analysis should be applicable to a wider range of piecewise-linear problems.     

迫弹激光引信用脉冲半导体激光电源的设计与应用

设计了适应于迫弹激光近炸引信的小体积、低电压、窄脉宽、高功率的脉冲半导体激光电源.采用电容充放电的模式,选用高速大功率MOSFET管作为开关,设计了相应的高速开关控制电路.激光电源模块的重复频率高达50kHz,常规热电池供电电压条件下的输出脉冲激光峰值功率为9W,光脉冲上升沿为4.2 ns,光脉宽为10 ns,为有效提...     

An ideal harmonic generator

A class of nonlinear resistive harmonic generators is considered in this paper. These generators are ideal in the sense that they generate only the desired harmonic into a resistance load and that they have power gain. Experimental results for tunnel diode approximations to the ideal curves are given for harmonics up to five.     

Nonlinear circuit analysis of harmonic and intermodulationdistortions in laser diodes under microwave direct modulation

A microwave nonlinear circuit analysis technique which can account for all known steady-state responses has been developed and applied to the large-signal characterization of directly modulation laser diodes. An equivalent circuit derived from the rate equations is used to model the laser diode. The proposed technique is based on a harmonic balance algorithm which represents two-tone inputs by describing frequencies. Second-harmonic and third-order intermodulation distortion results for a single-mode GaAlAs diode have been compared with corresponding measured data to validate the method. Aperiodic responses are detected by means of bifurcation theory prior to the harmonic balance analysis and are simulated in the time domain. Simulated results are shown to agree well with published measurements, and indicate the capability of using this approach for the computer-aided design of microwave fiber-optic transmitters     

串并联谐振逆变器的研究

文章针对串并联谐振拓扑在光伏发电中的应用,提出用高次谐波的阻抗去抵消基波的容性阻抗,从而减少开关管在关断时的续流电流,进而减少电磁干扰,提高输出电压的功率因数,最后通过仿真和试验验证了该方法的正确性。     

A novel approach to practical matrix converter motor drive system with reverse blocking IGBT

This paper proposes a novel control strategy and a protection circuit and shows the advantage of utilizing a newly developed reverse blocking insulated gate bipolar transistor (RB-IGBT), to solve several practical problems of the matrix converter. The proposed control strategy is based on a virtual indirect control method with a virtual rectifier and a virtual inverter. Pulse-width modulated (PWM) pulses for the matrix converter are obtained by combining PWM pulses for the virtual rectifier and inverter. As a result, the control part of the input current and output voltage can be clearly separated. Thus, the conventional inverter control algorithms can be applied to the virtual inverter control. The advantage of this method is confirmed by experimental results with a 22-kW induction motor drive system. Good sinusoidal waveforms are obtained for the input and output currents, and the total harmonic distortion (THD) of the input and output current are 5.1% and 1.4%, respectively. The conduction loss of the RB-IGBT is decreased to about two-thirds of the conventional ac switch with series connection diode. Thus, the converter loss is about a half to the conventional PWM rectifier-inverter system with the same capacity. Furthermore, the protection problem is solved by a dynamic clamp method without an electrolytic capacitor. This protection circuit directly dissipates reactive load energy by dynamic clamp operation of an IGBT.     

Design of Ka-band antipodal finline mixer and detector

This paper mainly discusses the analysis and design of a finline single-ended mixer and detector. In the circuit, for the purpose of eliminating high-order resonant modes and improving transition loss, metallic via holes are implemented along the mounting edge of the substrate embedded in the split-block of the WG-finline-microstrip transition. Meanwhile, a Ka band slow-wave and bandstop filter, which represents a reactive termination, is designed for the utilization of idle frequencies and operation frequencies energy. Full-wave analysis is carried out to optimize the input matching network of the mixer and the detector circuit using lumped elements to model the nonlinear diode. The exported S-matrix of the optimized circuit is used for conversion loss and voltage sensitivity analysis.The lowest measured conversion loss is 3.52 dB at 32.2 GHz; the conversion loss is flat and less than 5.68 dB in the frequency band of 29-34 GHz. The highest measured zero-bias voltage sensitivity is 1450 mV/mW at 38.6 GHz,and the sensitivity is better than 1000 mV/mW in the frequency band of 38-40 GHz.     

FD MOS SOI circuit to enhance the ratio of illuminated to dark current of a co-integrated a-Si:H photodiode

In this paper we first present the integration of amorphous silicon photodiodes with a fully depleted silicon on isolator (FD SOI) MOSFET circuit. Taking the advantage of the better subthreshold characteristic of FD SOI MOSFETs with respect to bulk devices, a very simple SOI circuit integrated with the amorphous silicon photodiode is presented to significantly improve the ratio of the circuit output current when the diode is illuminated to when it is not. The use of one additional reference source voltage to adjust the operating point of the photodiode, allows to obtain a very significant increase in this current ratio, much higher than what can be obtained using a simple diode. Circuit solutions used to amplify the diode current under illumination are usually more complicated and involve a capacitor or more transistors than the circuit we present. All the other properties of the photodetector, as its spectral characteristic and linear dependence of detection with light intensity are maintained. The circuit can also be used in conjunction with other circuits for further amplification and/or processing.     

Perturbation-Based Stochastic Modeling of Nonlinear Circuits

This paper presents a general model for a nonlinear circuit, in which, the circuit parameters (e.g. resistance and capacitance) are subject to random fluctuations due to noise, which vary with time. The fluctuating amplitudes of these parameters are assumed to be Ornstein–Uhlenbeck (O.U.) processes and not the white noise owing to temporal correlations. The nonlinear circuit is represented by a system of nonlinear differential equations depending upon a set of parameters that fluctuate slowly with time. To model these fluctuations, we use the theory of Ito’s stochastic differential equations (SDEs). Then the driving force of the circuit dynamics is in accordance with the general perturbation theory decomposed into the sum of a strong linear component and a weak nonlinear component by the introduction of a small perturbation parameter. The circuit states are expanded in the powers of this small perturbation parameter and recursive solutions to the various approximates obtained. Finally, the approximate expressions for the output states are obtained as stochastic integrals with respect to Brownian motion processes. The proposed method is applied to a half-wave rectifier circuit which is built out of a diode, a resistor and a capacitor. The diode is represented by nonlinear voltage–current equation, and resistance and capacitance are subject to random fluctuations due to noise, which vary slowly with time. The results, obtained using the proposed method, are compared with those obtained via the conventional perturbation-based deterministic differential equations model for a nonlinear circuit. Hence, the noise process component, present at the output, is obtained.     

Spreading Resistance as a Function of Frequency

The equivalent circuit applicable to most semiconductor diodes contains a term R/sub s/ called the spreading resistance which is a very critical parameter of any diode. In a mixer diode, R/sub s/ limits the conversion efficiency and increases the noise temperature. In parametric amplifiers, R/sub s/ affects the overall impedance levels and determines the minimum noise figure of which the amplifier is capable. In harmonic generators it drastically affects the conversion efficiency, as it dissipates power not only at the input and output harmonic frequencies but also at every idler frequency for which current may flow through the diode. This paper details more specifically the problems encountered when high frequency operation must be evaluated. The cylindrical capacitor is examined with emphasis on the configuration which applies to the variable-capacitor diode, which is used primarily for harmonic power generation. The point-contact diode configuration is examined and the field equations are derived in terms of the oblate spheroidal coordinates. It is shown that this is the natural coordinate system for such an analysis and that the spreading resistance is quite easily derived in this system.     

PIN光电探测器等效电路模型研究

本文给出一个新的PIN光电二极管的等效电路模型，该模型基于速率方程和微波端口特性并在TMS（TsinghuaMicrowaveSpice）中完成，可以进行线性、非线性信号分析和噪声分析。利用该模型对其非线性谐波特性进行了预测，模拟结果表明和文献数值求解结果基本一致，最后讨论了适用于金属－半导体－金属（MSM）光电二极管的修正模型．     

TRAPATT oscillations in a p-i-n avalanche diode

The characteristics of TRAPATT oscillations in a p-in diode are discussed and an approximate semi-analytical solution for the diode voltage waveform is derived when the diode current is a square wave. It is shown that a traveling avalanche zone is not necessary to generate a dense "trapped" plasma and that the boundary conditions prevent the trapped plasma from completely filling the depletion layer. Typical voltage waveforms and corresponding diode power, efficiency, and impedance at the fundamental and higher harmonics are presented. When the diode current is a square wave the diode does not necessarily exhibit a negative resistance at all higher harmonics. A computer program for TRAPATT oscillations in a p-i-n diode is described. Its running time is two or three orders of magnitude less than more exact time domain computer analyses. Typical results of diode power, dc to RF conversion efficiency, and required circuit impedances are presented for several different current waveforms which are composed of up to the seventh harmonic of a square wave and the first two harmonics of a half-wave sine wave. It is shown that high-efficiency oscillations are possible with diode currents composed of only the fundamental and one harmonic.     

A novel PWM scheme for single-phase three-levelpower-factor-correction circuit

This paper presents a control scheme for a single-phase AC-to-DC power converter with three-level pulsewidth modulation. A single-phase power-factor-correction circuit is proposed to improve the power quality. The hysteresis current control technique for a diode bridge, with two power switches is adopted to achieve a high power factor and low harmonic distortion. A control scheme is presented where the line current is driven to follow the reference sinusoidal current which is derived from the DC-link voltage regulator, the capacitor voltage balance compensator and the output power estimator. The blocking voltage of each power device is clamped to half of the DC-link voltage. The high power factor and low current total harmonic distortion are verified by computer simulations and hardware tests