Harmonics reduction of three-phase boost rectifier by modulating duty ratio (original) (raw)
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Digital implementation of harmonics reduction of three-phase boost rectifier
2010
The line currents of three-phase diode bridge rectifier suffer from high THD. This THD is higher than IEEE standards. Injection of six harmonic components to the control signal of the boost converter connected to the three-phase diode bridge rectifier reduces the THD of the utility line current. In this paper a digital implementation of injecting six harmonic to the control signal of three-phase boost rectifier is shown. The digital implementation is carried out by using FPGA. In this study a sin-wave and a triangle-wave with six times the fundamental frequency and variable amplitude are digitally generated in the FPGA. Each signal is added to the dc control signal component of boost converter to be compared with digitally generated saw-tooth. The simulation and experimental results show that the THD of the utility line currents depends on the amplitude and phase-shift of the six-order component injected to the control signal of the boost converter and the angle of input three-phase voltage.
Minimizing Current Distortion of a Three-Phase Bridge Rectifier Based on Line Injection Technique
IEEE Transactions on Power Electronics, 2006
This paper demonstrates a new concept and a novel passive resonant construction, which is connected between the ac and dc sides of the three-phase bridge rectifier, for reducing line current harmonics. This resonant net connection, in combination with the conduction intervals of each diode, generates a circulating third harmonic current between the ac and dc sides of the diode rectifier. This will cause a significant reduction in line current harmonics. As a result of this, the shape of line current becomes nearly sinusoidal. Results of analytical, simulation, and experimental verification on a typical example are presented. The total harmonic distortion (THD) of the line current can be reduced from 32% to 5%. Therefore, based on this concept a very cheap, lossless, and passive rectifier with low THD and almost unity power factor has been developed.
Tikrit Journal of Engineering Sciences
The aim of this paper is to analyze the influence of adding serial inductance in AC side of the 3ph -6 pulse bridge rectifier on the reduction of harmonic distortion rate. A simulated model with serial inductance was analyzed. The 3-phase 6-pulse diode bridge rectifier was chosen because it corresponds to the operation of the 6-pulse thyristor bridge rectifier at maximum load (while keeping the angle α = 0). Both the total harmonic distortion (THDi) and the power factor (PF) for the circuit have been measured. The results obtained of the THDi has been recorded for four values of serial inductance and results was compared with the (IEEE 519-1992) standard. Comparison results indicates that for values of inductive reactance (Xi) up to 67% cause a reduction of THDi which is above the standard values, while for (Xi) more than 67% cause a reduction in THDi within the acceptable standard level. Analyzing of results prove that the adding of serial inductance at the AC side leads t...
Electric Power Systems Research, 2009
This paper presents a new approach to eliminate harmonics and to improve power factor of a three phase front-end uncontrolled rectifier. A high-power-factor is achieved by injecting high-frequency triangular current from the output of three-phase inverter. The high frequency (HF) current modulates the rectifier input voltage resulting in conduction of diodes into each switching cycle. The resulting ac input line current is continuous and sinusoidal in shape with significant reduction in current harmonics. All the switches are operated at zero-voltage switching (ZVS). The diodes of the rectifier are also operated with soft switching at turn-on as well as at turn-off. Varying switching frequency with fixed duty ratio regulates the output voltage. The proposed ac-to-dc converter also maintains high-power-factor even for unbalanced input supply voltages. The analysis of the converter is carried out on a single-phase basis, using different operating modes in one switching cycle of injected current. Theoretical results based on analysis are verified initially through digital simulation, and confirmed by using an experimental prototype of 2.5 kW.
Harmonics Issues of Three-Phase Diode Rectifiers with a Small DC Link Capacitor
This paper presents effects of DC link capacitor sizes in a three phase diode rectifier on input current harmonics at a system level. A small DC link capacitor generates a resonant frequency with a line inductor which can affect and increase the input current harmonics. According to IEC 61000-3-2 and IEC 61000-3-12 standards, low order current harmonics of a power electronic system should be controlled below a certain limits but at a power system level, voltage harmonics are important and should be reduced. SABER simulations have been carried out for a three phase motor drive system with different DC link capacitors and at different power levels in order to analyze the input current harmonics and the power quality of the power network.
A Novel Three-Phase Diode Boost Rectifier Using Hybrid Half-DC-Bus-Voltage Rated Boost Converter
IEEE Transactions on Industrial Electronics, 2000
A novel three-phase diode boost rectifier is proposed in this paper. The core of the proposed topology is a power conversion device [the loss-free transformer (LFT)] with two terminals; one input and one output. The input is parallel-connected with the dc bus capacitor, while the output is connected between the rectifier plus rail and the dc bus plus rail. The LFT is controlled in such a way to control the rectifier current and boost the dc bus voltage. In contrast to the ordinary boost rectifiers, the switches of the new boost rectifier are rated on a fraction of the dc bus voltage and a fraction of the input current. It makes this topology very compact and efficient. Power rating, size, and losses depend strongly on the ratio of the dc bus voltage to rectifier voltage (boosting factor). For example, if the boosting factor is low, below 1.5, the power converter efficiency could be 98-99%. The proposed boost rectifier has been analyzed and experimentally verified on a 5.5-kW prototype. The results are presented and discussed.
The design of duty-cycle modulated three-phase boost rectifiers
Orthodontic Waves, 1999
Duty-cycle modulation of single-switch three-phase boost rectifiers has been demonstrated to be an effective way of reducing their input current harmonics. But a converter design methodology for such control approach is not available yet. This paper intends to fulfill this lack, presenting a design approach for this operation mode. Design equations are provided for some operation conditions, and experimental results validate the approach