Integrated active rectifier and power quality compensator withreduced current measurement

This paper describes a three-phase integrated active rectifier and shunt power quality compensator (IPQC). The measurement of only three currents is required, and the control algorithm can be implemented using a low-cost controller. The IPQC improves the harmonic content of the supply current, displacement power factor, supply current balance, and can serve as a four-quadrant active rectifier for motor drives and other DC-link loads. The operation of the IPQC is experimentally verified using a conventional three-phase insulated gate bipolar transistor voltage-source inverter. A low-cost fixed-point DSP-based controller with fixed-band hysteresis current regulation is used for the implementation of the control algorithms     

An active power filter and unbalanced current compensator

This paper presents the synthesis and performance of a shunt active power filter based on the three-phase pulsewidth modulation (PWM) voltage converter connected to the AC mains. Current harmonics and asymmetries caused by nonlinear loads can be compensated. A decoupled system in Park's variables is achieved and so simple controllers with excellent performance can be used. The controllers are implemented directly in the Park's referential. Expressions for the controller's synthesis are derived. Experimental results from a 2 kVA IGBT prototype showing excellent dynamic and steady-state system's performances are presented. The control circuit is implemented with analog and digital electronic circuits. A considerable amount of electronic circuits are needed. The method presented in this paper can also be implemented with a digital signal processor     

A novel control algorithm for active power conditioner without load current sensor

A novel control algorithm for an active power conditioner (APC) is proposed. The operation of this APC can be divided into two modes: active power filter mode and back-up power mode. When the mains are normal, the proposed APC operates in the active power filter mode that provides the functions of active power filter and battery charger. Once the mains have failed, the proposed APC operates in the back-up power mode to supply power to the demands. In this circuit design, the control circuit is suitable for both operation modes except in the arrangement of feedback signals. Hence, the design cost can be reduced; also, no load current sensor is used in the circuit. The practicality of the method is, therefore, further enhanced.     

A novel design of line-interactive uninterruptible power supplies without load current sensors

In this paper, a new approach for the design of line interactive uninterruptible power supplies (UPS) without load current sensors is proposed. Based on the interactive structure, this system is constructed that includes the power factor improvement capability in anticipation of increasing the quality of supplying power. With the employment of such an approach, the power converter can be adaptively operated at the active power filter mode or backup mode, by which the power can be supplied to the connected load very reliably. Moreover, as the proposed circuit needs only one current feedback signal where the load current sensors can be saved, the circuit design can be thus simplified significantly. In order to confirm the effectiveness of this proposed design, the approach has been tested through the theoretical analysis and experimental validation under different test scenarios. Test results help support the feasibility and practicality of the method for the application considered.     

A novel high power self-commutated static var compensator for load compensation

A novel high power self-commutated static var compensator for load compensation is proposed. The harmonics are eliminated by combining low frequency high power devices and high frequency low power devices. A modified control strategy is also proposed for applications involving high and faster rates of change in var demand. Detailed simulation studies for single phase and three phase topologies are presented.     

Single-switch parallel power factor correction AC-DC converters with inherent load current feedback

Single-stage power factor correction (PFC) ac-dc converters usually suffer from high bulk capacitor voltage stress and extra switch current stress. Bulk capacitor voltage feedback with a coupled-winding structure can dramatically alleviate the stresses. However, this type of feedback is indirect because the feedback only occurs after the bulk capacitor voltage increases. This paper presents a family of single-switch single-stage parallel PFC ac-dc converters with inherent load current feedback. Unlike the bulk capacitor voltage feedback, which utilizes the decreased duty ratio and the increased bulk capacitor voltage to reduce the input power at light load, the load current feedback can reduce the input power automatically at light load while maintaining an unchanged duty ratio. The proposed converters combine the advantages of simple topology, low bulk capacitor voltage, and no extra current stress across the switch. The concept is verified using an ac-dc converter with universal-line input and 5-V, 60-W output power. The input current harmonics meet IEC1000-3-2 Class D requirements.     

考虑电力系统非线性负荷的电子式电流互感器谐波计量方法

传统电子式电流互感器谐波计量方法无法获取负荷参量特征,电流互感器谐波输出不稳定,导致该方法的计量性能不理想,电流互感器谐波干扰问题没有得到有效解决.因此,提出基于电力系统非线性负荷的电子式电流互感器谐波计量方法.构建电子式电流互感器谐波参数采集模型,融合电流互感器谐波振荡,提取自相关谱特征量.通过电阻元件敏感参数分析,...     

Control of power factor correcting boost converter withoutinstantaneous measurement of input current

This paper proposes a new control method for the constant-frequency control of power factor correcting boost power converter using a sinewave template modulated PWM signal which eliminates the need for instantaneous measurement of the line current for the switching control of the boost converter. The control strategy is based on the notion that the line current can be forced to trace a deterministic waveform such as a sinusoid by considering the implicit model of the sinewave in the boost converter controller structure. The modulating sinewave template is generated using the line voltage, the boost converter output voltage and the load current. The paper provides the analysis and the design of the controller and presents simulation and implementation results to demonstrate its effectiveness     

电阻负载系数的精密测量

电阻在负载状态下,由于电流作功发热而引起电阻的温升,从而使其电阻值发生变化.这种现象称为电阻的负载效应.因此电阻的温升和其负载之间的普通关系可以用一个负载的幂级数来描述.     

Integrated polarization compensator for WDM waveguidedemultiplexers

An integrated polarization compensator for wavelength-division-multiplexed waveguide demultiplexers is proposed and experimentally demonstrated. It is simple to fabricate, has many advantages over previously reported polarization compensation schemes, and is effective in both etched diffraction grating and arrayed waveguide grating based devices     

Quiescent power supply current measurement for CMOS IC defectdetection

Quiescent power supply current (I_DDQ) measurement is a very effective technique for detecting in CMOS integrated circuits (ICs). This technique uniquely detects certain CMOS IC defects such as gate oxide shorts, defective p-n junctions, and parasitic transistor leakage. In addition, I_DDQ monitoring will detect all stuck-at faults with the advantage of using a node toggling test set that has fewer test vectors than a stuck-at test set. Individual CMOS ICs from three different fabrication sites had a unique pattern or fingerprint of elevated I_DDQ states for a given test set. When I_DDQ testing was added to conventional functional test sets, the percentage increase in failures ranged from 60% to 182% for a sample of microprocessor, RAM, and ROM CMOS ICs     

Rapid detection and measurement of 3-phase reactive power, power and power factor

Established means for measuring or detecting reactive power, power or power factor have an inherent time delay, mainly because of the need for output filtering. This letter describes an arrangement employing sampling techniques, which, since no filtering is necessary, offers substantial advantages for control and monitoring applications.     

Single-phase integrated power quality compensator based oncapacitor-clamped configuration

A control scheme of an integrated power quality compensator, which employs an active rectifier to work simultaneously as an active power filter (APF) to decrease current harmonics, is proposed. The employed rectifier is based on a capacitor-clamped configuration to produce multilevel pulsewidth modulation waveforms which result in low voltage stress and low conduction loss on the power switches. The proposed active rectifier is controlled to track the supply current to be a sinusoidal wave with low current harmonics. The advantages of the proposed control scheme are high power factor, low current harmonics, no complicated calculations for current harmonics elimination, and no dedicated APF needed for harmonic elimination. The experimental results are used to verify the validity and effectiveness of the proposed control scheme     

AC line voltage harmonics compensator with excessive current control

We investigate an instantaneous common terminal voltage-controlled harmonics compensator constructed by a shunt active filter with an appropriate series inductance including the line impedance. This compensator can reduce or compensate both the ac line voltage distortion derived from the downstream utility source voltage harmonics and the upstream current harmonics by nonlinear loads at the same time. The control system can be easily constructed without directly detecting the common terminal voltage to be compensated. Therefore, the main circuit configuration and the control system are simple. The harmonics compensation level and the compensation current can be easily adjusted by changing the feedback gain for the sensing inductance voltage drop. In this paper, we describe the basic principle of the control method, the modified control method, the circuit construction by the pulsewidth-modulation-controlled shunt active filter and the control system of the compensator. Then, we show some operating waveforms for the cases of the downstream voltage distortion and the upstream harmonics current from the nonlinear loads by simulation analysis and experiments to verify the feasibility.     

Integrated ZCS quasi-resonant power factor correction converterbased on flyback topology

An integrated zero current switching (ZCS) quasiresonant converter (QRC) for the power factor correction with a single switch is presented in this paper. The power factor correction can be achieved by the discontinuous conduction mode (DCM) operation of an input current. The proposed converter offers good power factor, low level line current harmonics, and tight output regulation. The design equations are suggested and a prototype converter has been designed based on these equations and experimentally investigated. The input current waveform of the prototype shows less than 15% of total harmonic distortion. Also, the efficiency and power factor of about 84% and 0.977, respectively, can be obtained under the rated condition     

Single current sensor control for single-phase active power factor correction

This paper presents the realization of a boost-type active power factor corrector (APFC) using a single current sensor to sense the inductor current for input current shaping and output voltage regulation. Neither input voltage nor output voltage sensing is needed. The sensed inductor current is used for two main functions. The first one is for comparing with a sawtooth signal in order to shape the input current waveform. The second one is for determining the input and output voltages by processing the rate of change of the inductor current when the main switch is in on and off states, respectively. Compared with conventional APFCs, the proposed technique has several advantages. First, no dissipative voltage divider is required. Second, electrical isolation between the power conversion stage and the control stage can be achieved inherently. Finally, no complicated or sophisticated digital sampling and numerical computations are needed. The applicability and accuracy of the proposed technique have been studied experimentally. Steady-state behavior and large-signal response under output load disturbance are also investigated.     

Digital implementation of a line current shaping algorithm for three phase high power factor boost rectifier without input voltage sensing

In this paper the implementation of a simple yet high performance digital current mode controller that achieves high power factor operation for three phase boost rectifier is described. The indicated objective is achieved without input voltage sensing and without transformation of the control variables into rotating reference frame. The controller uses the concept of resistance emulation for shaping of input current like input voltage in digital implementation. Two decoupled fixed frequency current mode controllers calculate the switching instants for equivalent single phase boost rectifiers. A combined switching strategy is developed in the form of space vectors to simultaneously satisfy the timing requirements of both the current mode controllers in a switching period. Conventional phase locked loop (PLL) is not required as converter switching is self-synchronized with the input voltage. Analytical formula is derived to obtain the steady state stability condition of the converter. A linear, low frequency, small signal model of the three phase boost rectifier is developed and verified by measurement of the voltage control transfer function. In implementation Texas Instruments's DSP TMS320F240F is used as the digital controller. The algorithm is tested on a 10-kW, 700-V dc, three phase boost rectifier.     

Micromechanical gain slope compensator for spectrally linearoptical power equalization

We present a device which produces changes in the slope of its transmitted spectra via an applied bias, a spectrally linear optical power equalizer (SLOPE) device. This device may have application for equalizing power levels in optical networks when simple gain tilt is all that is required, for example in optical power amplifiers     

A novel digital compensation technique for current bias without additional power consumption

A new digital compensation technique is proposed for current reference. The current variations induced by deviations of temperature and process are calibrated through a digital method. The circuit structure is simplified, and the problem of instability in conventional analog current bias can be overcome since the digital part cut off the closed compensation loop. Designed with 0.18 μm CMOS technology, the output current can be calibrated to 100 μA with a maximum error of ±0.3 μA under all the process corners, no matter how the temperature changes in an ultra-wide range of ?116 to 160 °C. In addition, the current precision can be maintained as the load voltage varies in the range of 0.31–1.04 V, and the load sensitivity is about 8,000 ppm/V. The digital part can be shut down after the calibration phase, so no additional power will be consumed except the bias itself.