A novel control method for input output harmonic elimination of thePWM boost type rectifier under unbalanced operating conditions

This paper presents a new control strategy to improve the performance of the PWM boost type rectifier when operating under an unbalanced supply. An analytical solution for harmonic elimination under unbalanced input voltages is obtained resulting in a smooth (constant) power flow from AC to DC side in spite of the unbalanced voltage condition. Based on the analysis of the open loop configuration, a closed loop control solution is proposed. Simulation results show excellent response and stable operation of the new rectifier control algorithm. A laboratory prototype has been designed to verify the discussions and analyses done in this paper. Theoretical and experimental results show excellent agreement. Elimination of the possibility of low order AC and DC side harmonics due to unbalance is expected to materially affect the cost of DC link capacitor and AC side filter. The proposed method is particularly useful in applications where the large second harmonic at the DC link may have a severe impact on system stability of multiply connected converters on a common link     

Space vector-based analytical analysis of the input currentdistortion of a three-phase discontinuous-mode boost rectifier system

In this paper the low frequency harmonic distortion of the mains current of a three-phase single-switch discontinuous-mode boost-rectifier is calculated. The system analysis is based on application of space vector calculus and on substitution of discontinuous time shapes within a pulse period by quasicontinuous time shapes. The quasicontinuous time shapes are defined by averaging over the pulse period. The dependency of the shape of the input currents on the voltage transformation ratio is given for various control methods in analytical form. The results of the theoretical analysis are verified by digital simulation and by measurements on a laboratory model. A good consistency of the results has been found     

A DSP-based implementation of a new nonlinear control for a three-phase neutral point clamped boost rectifier prototype

This work presents the design and implementation of a nonlinear control strategy for a three-phase three-level neutral-point-clamped boost rectifier. The adopted control consists of nonlinear feedback linearization technique. The nonlinear state-space model of the rectifier was obtained in the dq0 reference frame. The input/output feedback linearization is then applied and the linearizing control law is derived. Therefore, the resulting model is linearized and decoupled in three independent subsystems. Afterwards, the stabilizing controllers are designed based on linear techniques to control line currents, output, and neutral point voltages. The control law is designed using Simulink/Matlab and applied to the converter via a 1.8-kHz pulsewidth modulator (PWM). Both control law and PWM signals are executed in real time using the DS1104 DSP of dSPACE. A 1.2 kW laboratory prototype is built for validation purposes. The proposed control law robustness is validated for diverse severe load and system parameter variations. It shows robust performance in terms of high power factor, low total harmonic distortion and output voltage ripples, small overshoot, and short settling time.     

A method for calculating harmonic currents of a three-phase bridgeuncontrolled rectifier with DC filter

A practical method is proposed for calculating the harmonic currents of a three-phase bridge uncontrolled rectifier with a DC filter, taking into account the AC source reactance. The method is based on the frequency-domain method and the rectifier switching functions. Analytical equations for the harmonic currents on both the DC and AC sides are derived. The validity of the method is demonstrated by comparison with the results of time simulation. The approach can be extended to the harmonic analysis of a thyristor rectifier as well as a rectifier with unbalanced line conditions     

A DSP-based implementation of a nonlinear model reference adaptive control for a three-phase three-level NPC boost rectifier prototype

In this paper, the design and the implementation of a model reference adaptive control (MRAC) applied to a three-phase three-level neutral-point-clamped (NPC) boost rectifier are presented. This control strategy is developed with a view to regulate dc output and neutral point voltages and to reduce the influence of parameter variations while maintaining unity power factor. A nonlinear multiple-input multiple-output (MIMO) state space model of the rectifier is then developed in dq0 reference frame. The proposed controller is based on the use of a feedback linearization technique followed by a robust MRAC scheme allowing the design of a suitable controller applied to the plant. The control law is designed in Simulink/Matlab and applied to the converter via a 1920-Hz pulse width modulator both executed in real time using the DS1104 DSP of dSPACE. A 1.25 kW laboratory prototype is developed for validation. The experimental results are given for different operating conditions: nominal power operation, balanced and unbalanced dc load steps, boost inductor variation, and reactive power control. The proposed control law performs perfectly in a wide operation range giving low output voltage ripple, low line-current THD, a small overshoot and a fast settling time under system parameters variation.     

A new control strategy to improve the performance of a PWM AC to DCconverter under unbalanced operating conditions

Abnormal harmonics of significant magnitude are generated at the output and input terminals of a PWM (pulse-width-modulated) AC-to-DC power converter under unbalanced operating conditions. A new control strategy is presented to selectively cancel the generated lower-order abnormal harmonics at the output and input terminals and thereby to preserve the high-performance features of a PWM AC-to-DC power converter. The proposed technique essentially involves computing the sequence components of the unbalanced input supply and suitably counter-unbalances the PWM gating signals of the power converter switches to cancel the generated abnormal harmonics. The technique is essentially a feedforward approach and is suitable for higher-power GTO (gate turn-off thyristor) type PWM AC-to-DC power converters. A procedure for implementing this technique in real time is discussed. Selected results are verified experimentally on a prototype PWM AC-to-DC power converter     

具有智能PowerPath控制的18V降压-升压型转换器以95%的效率从双输入提供>2A的电流

LTC3118通过整合一个双通道、低损耗的PowerPath控制器和一个高效率降压-升压型转换器解决了电源通路中的损耗、输入电源的优先级确定、以及源于电感电缆插入的电压尖峰均会增加系统的成本和复杂性的问题.     

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.     

A common mode voltage reduction in boost rectifier/inverter systemby shifting active voltage vector in a control period

This paper proposes a new space-vector pulse width modulation (SVPWM) strategy that can reduce the number of common mode voltage pulses in a three-phase boost rectifier/inverter system using a synchronized switching sequence. In the proposed SVPWM strategy, it is possible to eliminate one common mode voltage pulse in every control period by shifting the active voltage vectors of the inverter to align to those of the boost rectifier. Thus, a reduction in the total number of common mode voltage pulses and RMS motor leakage current can be obtained without extra hardware. Since the proposed SVPWM strategy can be simply implemented in software, it is widely applicable regardless of the power capacity of the converter and results in no increment of converter volume, weight and price. Moreover, because the proposed SVPWM strategy maintains the magnitude of the active voltage vector required for motor control and simply changes the distribution of the zero, voltage vector, it does not effect the control performance of the power converter     

New control scheme of three-phase PWM AC/DC converter without phase angle detection under the unbalanced input voltage conditions

In general, three-phase PWM AC/DC power converters have been implemented in the synchronous frame model to eliminate steady state errors effectively and to obtain fast transient response characteristics. However, controllers designed in such way would have input current harmonics and DC-link voltage ripples under the unbalanced input voltage conditions due to the assumption of the balanced input voltage conditions. This paper describes a new control scheme to minimize harmonic distortions of the input current and DC-link voltage in the converter under the unbalanced input voltage. conditions. The synchronous frame input voltage, which is considered as the input side back-EMF component, is regulated pertinently according to the input voltage conditions. The current command is selected to eliminate the reactive power and the second order harmonic component of active power. In this case, the analysis of the input voltage is implemented in the synchronous frame without detecting the phase angle and magnitude of each phase voltage. The proposed control scheme is simple and effectively minimizing the harmonic distortions in the input and output system under the unbalanced input voltage conditions.     

Regulation of a PWM rectifier in the unbalanced network state usinga generalized model

This study concerns the modeling and control of a pulse-width-modulated (PWM) rectifier in the case of network variations. The aim is to limit and stabilize variations of DC output voltage and line currents in such circumstances. Network variations can result in costly damage to power converters and their loads but a power converter such as the PWM rectifier, using cascade digital control, offers many capabilities to stabilize the system with optimized control. A generalized model of the PWM rectifier is first presented using the Clarke notation in order to separate the positive and negative sequences. The model is also extended to the harmonics. The cases of harmonic disturbance and an unbalanced network are then analyzed and an optimized regulation is presented for the latter case, validating the generalized model. Experimental results are proposed. The line current compensation loop method coupled with identification of network parameters offers a good solution to stabilize the PWM rectifier in an unbalanced network     

A novel load current control method for a leading power factorvoltage source PWM rectifier

A novel PWM voltage source rectifier, controlled by the load DC current instead of the DC voltage, has been developed. Its main characteristics are: (a) there is neither input current sensors nor DC voltage sensor; (b) it works with an unchangeable and predefined PWM pattern; (c) it presents a very strong stability; (d) its stability does not depend on the size of the DC capacitor; (e) it can work at leading power factor for all load conditions; and (f) it can also work with zero regulation for all load conditions. Digital simulations, analyses, and experiments confirm all these characteristics of the control method     

A scheme to improve PCE of differential-drive CMOS rectifier for low RF input power

In this paper, a scheme to improve power conversion efficiency (PCE) of differential-drive CMOS rectifier for low RF input power is proposed. Auxiliary transistors are utilized to provide forward body biasing for the primary transistors of the rectifier. As a result, the threshold voltages of the primary transistors are reduced. Hence, higher PCE is achieved for lower RF input power. The circuits are designed in a standard 180 nm CMOS technology. Measurement results exhibit a considerable PCE improvement by the proposed design at the RF input frequency of 916 MHz in the three-stage configuration. For 50 K\(\mathrm{{\Omega }}\) resistive load, the proposed rectifier has a maximum 10.9 % PCE improvement and requires 2 dB less RF input power to achieve the comparable peak PCE.     

峰值电流控制提高三相整流功率因数的方法

在对大电容滤波的三相不控整流电路仿真研究的基础上,指出了该电路存在的工程应用局限性。在分析电流谐波畸变与功率因数之间的理论关系的基础上,提出了一种峰值电流控制提高三相不控桥式整流电路功率因数的方法,并进行了试验验证,证明其在提高功率因数的同时,有效地降低了滤波电感的体积及重量,实现三相整流滤波电路的小型化设计,具有一定的工程应用价值。     

A novel control method for forced commutated cycloconverters usinginstantaneous values of input line-to-line voltages

The authors present a novel control method for forced commutated cycloconverters (PWM cycloconverters). Using this control method the sinusoidal input and output current waveforms and the unity input displacement factor can be obtained. Moreover, the compensation of the asymmetrical and/or harmonic contaminated input source voltages is easily realized. This control method allows the input displacement factor not to be controllable, but to be fixed at approximately unity. Since a unity input displacement factor is desirable for motordrive use for the PWM cycloconverters, this constraint is not a new obstacle. Feasibility of the proposed control method is verified by simulations and experiments     

A method to control the instability of a class of Laplace transform inversion algorithms

A simple method is presented for controlling the numerical instability, inherent in the Laplace transform inversion techniques, which are based on the truncation of Legendre function series expansions. A criterion characterizing the quality of the approximation is also proposed.     

一种IDC现网设备快速替换与网络优化方法

运营商的IDC网络运行时间过长,需要集中针对老旧设备进行网络接入平台设备替换和网络结构优化.本文采用3种新技术进行现场割接,最大限度的提高割接速度,减少对客户业务的影响.可有效缩短割接时间,使业务平滑过渡, 割接时间从30 min左右缩短至l～2 min,极大的减少了对客户业务的影响,从而提高了服务质量,保障公司收入.     

On a generalization of the extended boundary condition method

The elementary problem of scattering of an E-polarized plane wave by a circular perfectly conducting cylinder is used for verifying the efficiency of the boundary deformation method (BDM) that has recently been proposed as a generalization of the extended boundary condition method (EBCM). It is shown that the BDM can ensure the highly accurate fulfillment of the null-field condition on an interior contour spaced from the boundary in accordance with this method. However, when the accuracy of the fulfillment of the aforementioned condition on the contour near the boundary or on the boundary itself corresponds to the solution found for the current, this accuracy is substantially worse than the accuracy achieved in the case when the standard EBCM with a contour located near the boundary is applied. In addition, it is shown that, when the singularities of the wave field are enclosed by the contour chosen according to the BDM, a correct solution to the problem is not guaranteed.