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A new method for reducing harmonics involved in input voltages of a three-phase voltage source diode rectifier is proposed. It is applied to the conventional 6-step diode rectifier with a three-phase autotransformer. By injecting harmonics to the neutral point of the autotransformer from an auxiliary circuit, input voltages of the proposed diode rectifier can be almost the same as a conventional 36-step...
In two-level PWM rectifiers, two common control strategies are respectively VOC (Voltage Oriented Control) and DPC (Direct Power Control). In high power applications, the converter performance may suffer seriously from the non-ideal characteristics of the sampling and control system. The effects of the non-ideal characteristics will be analyzed in this paper for classic VOC, DPC and PDPC (Predictive...
This paper presents a model predictive control strategy to control the active and reactive powers for three-phase three-level NPC PWM rectifier directly. This method is based on converter model. It uses voltages and currents of the converter and does not use hysteresis or PI controllers for active and reactive powers control loop. This algorithm is robust against to tolerances of input inductances...
The characteristic to shield harmonics of the novel converter transformers is presented in this paper. Then design the DC transmission system of the novel transformer to achieve harmonics shielding function, by adopting the novel transformer on the rectifier side. Based on the calculation method of harmonic content in the HVDC system, calculate and allocate the reactive power compensation on both...
This paper proposes a control method of DC-link shunt compensator (DSC) located to DC-node in three-phase diode rectifier system. The circuit can substitute for bulky components such as DC reactor filter and DC-link capacitor from conventional three-phase system. Hence the system can be miniaturized and becomes lighter by reducing heavy passive components. DSC supplies harmonic current into diode...
The matrix converter (MC) is an alternative ac-ac power converter by connecting directly input to output phases through bidirectional switches and without using any dc-link or energy storing element, therefore is called an all-silicon converter. Two topologies of matrix converter are established such as direct topology and the indirect topology. This paper is devoting to presents the topology of the...
In this paper, an active interphase transformer is implemented in 12-pulse diode bridge rectifier system. This system draws near sinusoidal supply from the utility. In this paper, simulation results are provided for two schemes. Scheme I consists of an autotransformer (0.2 P0 (PU)), two active interphase transformer, two diode bridge rectifiers & PWM VSI. A PWM VSI injects triangular shaped current...
This paper proposes a constant instantaneous power based controller for a shunt active power filter system (SAPF). A SAPF has been designed, built to work under balanced; unbalanced and distorted supply conditions to meet IEEE 519 recommended harmonic standards. The shunt active filter is controlled by a constant instantaneous power based controller to act as a harmonic isolator among the supply and...
In this paper a new control method is introduced for grid-connected inverter (GCI) to inject sinusoidal current to grid in presence of nonlinear load and distorted grid voltage conditions. The proposed control method consists of two parts: current reference generation and current controller. To generate current reference, a new algorithm, based on Recursive Discrete Fourier Transform, is proposed...
In this paper, the asymptotic tracking and disturbance rejection algorithm is revisited. It is applied in voltage source converter controller design to realize steady-state error when the reference is a sinusoidal signal. Detailed design procedures are also developed and described. Circuit level simulations are carried out, and results show the effectiveness of reference tracking and disturbance rejection...
Low-voltage high-current electrolysis rectifier systems are widely used in large-scale electrolysis factories. It consists of several rectifier transformers in a parallel mode with proper phase shifts. The increased pulse numbers of the rectifier system can eliminate harmonics of certain orders. In this paper, an 84-pulse rectifier system applied in aluminum electrolysis factories is designed according...
This paper relies on the development of a model for an urban electric transportation system. This model is used to simulate the system operation both in normal and abnormal (short circuit) regimes. The simulation results are compared with the results of some theoretical studies presented in the technical literature and also with some experimental results. Unlike the theoretical idealized studies our...
High efficiency and low Total Harmonic Distortion (THD) rectifiers have become a standard in the telecom industry. This paper describes the development of a digitally controlled Delta three-phase PFC to meet this standard. One way of improving efficiency is to reduce switching losses of the switching devices. This reduction could be achieved by modulation of the control output. This paper analyzes...
This paper presents a control of single-phase grid-interactive inverters with nonlinear loads. The utility-connected inverter should operate at both stand-alone and grid-connected modes. However, the waveform qualities of the grid current in grid-connected mode and the output voltage in stand-alone mode are poor under the nonlinear critical load with the conventional control. The impact of the nonlinear...
High-power single-phase PWM rectifiers for medium voltage drives operate at low switching frequency to maintain the switching losses of the power semi-conductor devices at an acceptable level. For these applications, selective harmonic eliminated pulse width modulation and synchronous optimal pulse width modulation methods permit a good trade-off between switching losses and harmonic distortion of...
New efficiency-improving technique applicable for all types of shunt-diode rectifier is presented. The proposed technique using a harmonic-termination circuit improves the efficiency of conventional shunt-diode rectifiers by nearly 10% at 13.56 MHz. The efficiency of a shunt-diode rectifier was analyzed by using Fourier transform and it is concluded that the efficiency loss can be significantly reduced...
Harmonic armature reaction in brushless exciter is studied and simulated in this paper, and it is proved that harmonic armature reaction can effect the property of Brushless Exciter, such as changing voltage wave of armature, increase the loss of pole and armature energy in generator, but can not change the phase sequence. Harmonic armature reaction can be used to judge the fault diagnosis of rotating...
This work relates to active power filtering of line-commutated HVDC system using the definitions of active, reactive, and distortion power presented in one of the several power theories. The behavior of the rectifier terminal of a six-pulse, line-commutated, series compensated HVDC system is analyzed for instantaneous power oscillations. Shunt compensation is done based on the power theory under discussion...
The fundamental theory and control methods of Active Power Factor Correction (short for APFC) are introduced in this paper. It analyzes and studies the APFC based on the average current control single-phase Boost type APFC circuit. In addition, the simulation model is built on the MATLAB and the results are shown in this paper. The results show the average current control single-phase Boost type APFC...
In this paper, The rectifier and inverter in three phase PWM drive motor system is studied. Based on Fourier Transform, Mathematical models of common mode noise source of rectifier are builded. A general modeling method for common mode noise source of inverters is presented based on the principle of the double Fourier integral. PWM carrier wave and fundamental wave function are described by two independence...
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