Ultra-low voltage common-mode voltage detector circuit

A new common-mode voltage detector circuit to be used in the common-mode feedback loop of ultra-low voltage fully differential amplifiers is presented. The proposed circuit behaves linearly for most of the signal range and is able to operate with supply voltages as low as 0.4 V. The design issues and simulation results of the circuit in 0.18 m CMOS technology are presented.     

消除共模电压的放大器

有史以来(或至少是有精密电子以来),模拟设计者最头痛的问题之一就是CMV(共模电压)带来的误差,或称之为可怕的地回路.尽管恐惧冲击着工程师们的心灵,但CMV并没有什么特别神秘之处.CMV误差的产生原因很简单:不同位置上电路的公共电压基准(即:地),如一个机箱的传感器和另一个机箱的ADC,两个基准电位是不同的.     

Design and performance of a passive EMI filter for use with a voltage-source PWM inverter having sinusoidal output voltage and zero common-mode voltage

This paper deals with integrating a small-sized passive electromagnetic interference (EMI) filter with a voltage-source pulse-width modulated (PWM) inverter. The purpose of the filter is to eliminate both high-frequency common-mode and normal-mode voltages from the three-phase output voltages of the inverter. A laboratory system consisting of a 5-kVA inverter, a 3.7-kW induction motor, and a specially-designed passive EMI filter was constructed to verify the viability and effectiveness of the filter. As a result, both line-to-line and line-to-neutral output voltages look purely sinusoidal as if the inverter were an ideal three-phase variable-voltage, variable-frequency power supply when viewed from the motor terminals. This results in a complete solution to serious EMI issues related to high-frequency common-mode and normal-mode voltages produced by the PWM inverter.     

三相电压型准阻抗源AC～AC变换器

摘要：为了克服传统三相斩控式交流调压器的不足,提出了一种三相电压型准阻抗源变换器电路拓扑。研究了其拓扑结构和工作原理,推导了输出电压与占空比的定量关系。运用matlab对电路进行了仿真,并根据仿真结果建立了实验电路,采用脉冲宽度调制法（PWM）对电路进行总体控制,得到占空比为0.2与0.8时的三相电压波形。实验结果验证了三相电压型准阻抗源电压调节的的可靠性和可行性。     

Modeling and analysis of common-mode voltages generated in medium voltage PWM-CSI drives

Common-mode voltages appear in pulse-width modulated current-source inverters (PWM-CSIs) drives due to the operating principles of the input rectifier and the output inverter. This paper presents the modeling and analysis of a medium voltage current-source inverter drive, using the Matlab software. Simulated results of the model are in close agreement with experimental waveforms obtained from an industrial AC drive, which shows overvoltages of up to 100%, generating important insulation stresses at the motor stator terminals.     

An instantaneous peak detection method for three-phase sinusoidal signals

This paper presents a new amplitude detection method for three-phase sinusoidal signals. The proposed detection method is based on calculation of the Park transformation. This method measures the amplitude of three-phase signals instantaneously and the ideal and non-ideal conditions are analysed. An electronic circuit for implementing this method is developed and tested to demonstrate the performance of the proposed method.     

An active circuit for cancellation of common-mode voltage generatedby a PWM inverter

This paper proposes an active common-noise canceler (ACC) that is capable of eliminating the common-mode voltage produced by a pulsewidth modulation (PWM) inverter. An emitter follower using complementary transistors and a common-mode transformer are incorporated into the ACC, the design method of which is also presented in detail. Experiments using a prototype ACC, whose design and construction are discussed in this paper, verify its viability and effectiveness in eliminating common-mode voltage in a 3.7 kW induction motor drive using an insulated gate bipolar transistor (IGBT) inverter. Some experimental results show that the ACC makes significant contributions to reducing a ground current and a conducted electromagnetic interference (EMI). In addition, the ACC can prevent an electric shock on a nongrounded motor frame and can suppress motor shaft voltage     

Direct model-based predictive control scheme without cost function for voltage source inverters with reduced common-mode voltage

This paper presents a direct model-based predictive control scheme for voltage source inverters (VSIs) with reduced common-mode voltages (CMVs). The developed method directly finds optimal vectors without using repetitive calculation of a cost function. To adjust output currents with the CMVs in the range of –V_dc/6 to +V_dc/6, the developed method uses voltage vectors, as finite control resources, excluding zero voltage vectors which produce the CMVs in the VSI within ±V_dc/2. In a model-based predictive control (MPC), not using zero voltage vectors increases the output current ripples and the current errors. To alleviate these problems, the developed method uses two non-zero voltage vectors in one sampling step. In addition, the voltage vectors scheduled to be used are directly selected at every sampling step once the developed method calculates the future reference voltage vector, saving the efforts of repeatedly calculating the cost function. And the two non-zero voltage vectors are optimally allocated to make the output current approach the reference current as close as possible. Thus, low CMV, rapid current-following capability and sufficient output current ripple performance are attained by the developed method. The results of a simulation and an experiment verify the effectiveness of the developed method.     

基于三相电压追踪法的动态电压恢复器仿真研究

电力系统中电压骤升或骤降、电力谐波、三相不平衡等状况都可能导致电子、电机设备无法工作,甚至损坏。动态电压调节器,能在1~2毫秒之内产生补偿电压,抵消系统电压所受干扰,使负荷侧电压感受不到扰动,保证了敏感负荷的安全可靠运行。文章设计了一种基于三相电压追踪法的动态电压恢复器,采用MATLAB/SIMULINK建立仿真模型,仿真结果表明在电压发生骤降时,可以有效补偿电压损失,保证输出电压的稳定,证明了该方法的有效性。     

A new peak detection method for the three-phase sinusoidal signals

An instantaneous amplitude detection method for the three-phase sinusoidal signals is proposed. The proposed method can measure the amplitude of the three-phase signals without any delay by using only two of the three-phase signals. The performance of this method under the ideal and nonideal conditions is analyzed. To demonstrate the performance of the proposed method, an electronic circuit for implementing this method is developed and tested     

Memcapacitor response under step and sinusoidal voltage excitations

Recently, mem-elements have become fundamental in the circuit theory through promising potential applications based on the built-in memory-properties of these elements. In this paper, the mathematical analysis of the memcapacitor model is derived and the effect of different voltage excitation signals is studied for the linear dopant model. General closed form expressions and analyses are presented to describe the memcapacitor behavior under DC step and sinusoidal voltage excitations. Furthermore, the step and sinusoidal responses are used to analyze the memcapacitor response under any periodic signal using Fourier series expansion where the effect of the DC component on the output response is investigated. In addition, the stored energy in the memcapacitor under step, sinusoidal and square wave excitations is discussed. Moreover, the analysis of series and parallel connection of N non-matched memcapacitors in general is introduced and special cases of matched memcapacitors are discussed. The derived equations are verified using SPICE simulations showing great matching.     

Extension of inductor voltage control to three-phase buck-typeAC-DC converter

A novel inductor voltage control (IVC) method capable of achieving near unity power factor is being proposed for buck-type AC-DC pulsewidth-modulated (PWM) converters. In this method, the input inductor voltages are kept within a hysteresis band about a sinusoidal template, thus ensuring sinusoidal input currents. This control method is much less sensitive to parameter and control variations than the existing delta modulation control (DMC) method. A companion paper has introduced the IVC method for the case of a single-phase buck-type converter. In the present paper, problems involved in direct extension of the IVC method to a three-phase buck converter are discussed first. Following this, a new switching logic scheme is proposed which enables these problems to be overcome and for IVC (as well as DMC) to be extended to a three-phase converter as well. Detailed simulation and experimental results have been provided to verify the expected good performance with IVC. The proposed IVC method has potential in applications such as those requiring AC-DC rectifiers with current limiting     

Small-signal modeling of pulse-width modulated switched-mode powerconverters

The state-space averaging method, associated with power converters, is discussed, Emphasis is on the motivation and objectives of modeling by equivalent circuits based on physical interpretation of state-space averaging. The discussion is limited to pulse-width-modulated DC-to-DC converters     

Application of a sinusoidal internal model to current control of three-phase utility-interface converters

Three-phase voltage-source converters are used as utility interfaces. In such a case, the converter line currents are required to track sinusoidal references synchronized with the utility grid without a steady-state error. In this paper a current control method based on a sinusoidal internal model is employed. The method uses a sine transfer function with a specified resonant frequency, which is called an S regulator. The combination of a conventional proportional-integral (PI) regulator and an S regulator is called a PIS regulator. The PIS regulator ensures that the steady-state error in response to any step changes in a reference signal at the resonant frequency and 0 Hz reduces to zero. An experiment was carried out using a 1-kVA prototype of three utility-interface converters, a voltage-source rectifier, an active power filter, and static synchronous compensator. Almost perfect current-tracking performance could be observed.     

AC voltage and current sensorless control of three-phase PWM rectifiers

In this paper, a novel control scheme of three-phase PWM rectifiers eliminating both the AC input voltage and current sensors is proposed. The phase angle and the magnitude of the source voltage are estimated by controlling the deviation between the rectifier current and its model current to be zero. The input currents can be reconstructed from switching states of the PWM rectifier and the measured DC link currents. To eliminate the calculation time delay effect of the microprocessor, the currents ahead one sampling period are estimated by a state observer and then are used for feedback control. The proposed control scheme reduces the system cost and improves its reliability. The feasibility of the proposed AC sensorless technique for three-phase PWM rectifiers has been verified through experiments using a high performance DSP chip.     

Indirect current control of a unity power factor sinusoidal currentboost type three-phase rectifier

The indirect current control scheme has evolved from the success of the hysteresis current controlled voltage regulated rectifier, which has been shown to be capable of: unity and even leading power factor operation; near sinusoidal current waveforms; and bilateral power transfer without the need of bi-directional solid state power switches. The advance consists of replacing the inner hysteresis current feedback loop by the standard sinusoidal PWM control and in the process saving the cost of the current measuring transducers. The scheme is evaluated through tests on 1 KW size laboratory models and through digital simulations. A theory of the system dynamics is developed and stability boundaries are presented     

Unifying the concepts of offset voltage and common-mode rejection ratio [bipolar differential amplifiers]

A unified treatment of offset voltage and common-mode rejection ratio (CMRR) of bipolar differential amplifiers using large signal models is presented. The offset voltage expressions for the differential pair and 741 stages are first calculated in terms of transport model parameters. CMRR may then be calculated from these expressions. Two distinct mechanisms contributing to CMRR are identified.     

Electronically tunable sinusoidal oscillator circuit with current and voltage outputs

A new circuit configuration for the realisation of an electronically tunable sinusoidal oscillator is presented. The proposed circuit uses only one current backward transconductance amplifier (CBTA), two grounded capacitors and one resistor. Using current controlled CBTA (CC-CBTA) instead of the CBTA, the resistor can be completely removed. It has also current-mode (CM) and voltage-mode (VM) outputs, simultaneously. The workability of the proposed structure has been demonstrated by both simulation and experimental results.     

A carrier-based PWM method for three-phase four-leg voltage source converters

In this paper a voltage modulation method based on a triangular carrier wave for the three-phase four-leg voltage source converter is described. The four-leg converter can produce three output voltages independently with one additional leg. The proposed modulation method for the four-leg converter can be implemented with a single carrier by a simple but useful "offset voltage" concept. The method is equivalent to the so called three-dimensional space vector PWM method, but its implementation is much easier. The maximum magnitude of the balanced three-phase voltage and the maximum magnitude of zero sequence voltage, which can be synthesized simultaneously, are derived. The feasibility of the proposed modulation technique is verified by computer simulation and experimental results. These results show that a proposed carrier-based pulsewidth modulation (PWM) technique can be easily implemented without conventional computational burden.