共查询到20条相似文献,搜索用时 31 毫秒
1.
Sung-Chan Ahn Dong-Seok Hyun 《Power Electronics, IEEE Transactions on》2002,17(5):616-622
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. 相似文献
2.
Blaabjerg F. Casadei D. Klumpner C. Matteini M. 《Industrial Electronics, IEEE Transactions on》2002,49(2):289-296
In this paper, the input current performance of matrix converters is analyzed, especially with reference to the operating conditions determined by unbalanced supply voltages. The space-vector modulation (SVM) technique is utilized to calculate the duty cycles of the active voltage vectors that must be applied, in each switching cycle period, in order to satisfy the input and output requirements. A detailed theoretical analysis of the input current harmonic content under unbalanced input voltage conditions is presented for two different current modulation strategies. On the basis of numerical simulations as well as measurements on a laboratory prototype setup, the strategies' performance are compared and the validity of the theoretical investigation confirmed. It is concluded that, when the input voltages are unbalanced to a significant extent, a dynamic input current modulation strategy has to be preferred, since a lower harmonic line current distortion will appear 相似文献
3.
Vazquez N. Lopez J. Arau J. Hernandez C. Rodriguez E. 《Industrial Electronics, IEEE Transactions on》2005,52(1):132-138
In recent years, several AC/DC converters have been presented in order to meet the power quality regulations, while maintaining the lowest number of components with the purpose of minimizing the cost and complexity; for this purpose the active input current shaping technique was proposed. A new active input current shaper (AICS) is presented. Differently from the traditional series AICS, the proposed scheme connects the auxiliary output of the main converter in parallel with the rectified AC mains instead of the series connection. The proposed parallel scheme demands a current with a low harmonic content where the standard specifications are fulfilled. The operation, simulation, and experimental results of the proposed scheme are presented. 相似文献
4.
Ngandui E. Olivier G. April G.-E. Guimaraes C. 《Power Electronics, IEEE Transactions on》1997,12(2):332-342
Noncharacteristic harmonics of significant magnitude are produced at the output and input terminals of phase-controlled power converters under unbalanced voltage supply conditions. The concept of switching functions has been proposed before to evaluate the harmonics produced by a phase-controlled six-pulse power converter under both balanced and unbalanced power supply conditions. This paper extends the switching-functions approach to establish analytical equations for the DC output voltage harmonics produced by 12-, 18-, and 24-pulse power converters. The problem is approached from the standpoint of symmetrical voltage components. The increase in distortion under unbalance is caused by the appearance of a second harmonic component. A method, based on an asymmetrical firing angle, to cancel the second harmonic at the power converter output under unbalanced voltage supply is also presented. Cancellation of the second harmonic improves power converter DC output voltage quality 相似文献
5.
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 相似文献
6.
A three-phase pulse-width-modulated (PWM) half-controlled rectifier using a novel PWM control strategy whereby the low-order harmonic content in both the input current and the output voltage is reduced is presented. The circuit operates with a unity displacement factor at its input and uses minimum power components. The PWM strategy developed can be implemented on a three-phase half-controlled rectifier bridge with only three controlled switches to obtain PWM controlled rectification. Although the circuit operation is explained with force-commutated SCR switches, the basic controlled PWM operation is valid for any type of switch control. The circuit has wide applications ranging from rectifiers to battery chargers to motor drives. Even if an input current filter is desired, its size will be small due to the PWM pattern used 相似文献
7.
This paper proposes a novel mains voltage proportional input current control concept eliminating the multiplication of the output voltage controller output and the mains ac phase voltages for the derivation of mains phase current reference values of a three-phase/level/switch pulsewidth-modulated (VIENNA) rectifier system. Furthermore, the concept features low input current ripple amplitude as, e.g., achieved for space-vector modulation, a low amplitude of the third harmonic of the current flowing into the output voltage center point, and a wide range of modulation. The practical realization of the analog control concept as well as experimental results for application with a 5-kW prototype of the pulsewidth-modulated rectifier are presented. Furthermore, a control scheme which relies only on the absolute values of the input phase currents and a modified control scheme which does not require information about the mains phase voltages are presented. 相似文献
8.
A space vector-based rectifier regulator for AC/DC/AC converters 总被引:12,自引:0,他引:12
A voltage-sourced rectifier control scheme for use with AC/DC/AC variable speed drives is presented. A control scheme is derived that directly calculates the duration of time spent on the zero state and on each switching state adjacent to the reference vector, over a constant switching interval, in order to drive the line current vector to the reference vector. In addition, under transient conditions, when deadbeat control is not possible, a control scheme is presented that ensures that the line current vector is driven in the direction of the reference current vector. The current reference for the rectifier controller is derived from the bus voltage error and a feedforward term based on the estimated converter output power. The proposed space vector-based rectifier regulator is shown to exhibit improved harmonic and transient performance over existing per-phase duty cycle prediction methods, especially at modulation indices near unity. The deadbeat control of the rectifier input current is accomplished every half-cycle with constant switching frequency while still symmetrically distributing the zero state within the half-cycle period 相似文献
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10.
Applying the linear model of the high--power HF triode, the conditions of the optimal design are analyzed in the paper, proposing the injection of the second harmonic in the input and output circuits. The optimal content of the second harmonic is investigated assuming an equal injection of the second harmonic in the input and the output circuits. The results are compared to the similar results of the linear amplifier under the same conditions but without any injection and also with the amplifier with the injection of the third harmonics, previously published. 相似文献
11.
This paper presents a novel power factor correction technique for single-phase boost type AC-to-DC converters in continuous conduction mode. Instead of using the inductor current or switching device current, in this paper, the diode current in the boost converter is used to formulate the duty ratio of the switch in a special way which makes the input current sinusoidal and in phase with the input voltage. To improve the dynamic performance and minimize the input current harmonic components, a new double-injection compensation method is employed in the voltage feedback loop. The power factor corrector has the following advantages: (1) operation with constant switching frequency; (2) elimination of input voltage sensing, error amplifier in the current loop and multiplier in the output voltage feedback loop; (3) minimal total harmonic distortion in the input current; (4) fast dynamic response of the output voltage loop; and (5) simple implementation of the control circuit. The principles of operation of the proposed control scheme are explained. Simulation and experimental results are presented to verify the feasibility of the control strategy 相似文献
12.
In this paper, a high-performance single-phase AC-to-DC rectifier with input power factor correction is proposed. The proposed approach has many advantages, including fewer semiconductor components, simplified control, and high-performance features, and satisfies IEC 555 harmonic current standards. Simulation and experimental results obtained on a laboratory prototype are discussed. A hybrid power module of the proposed approach is also shown 相似文献
13.
A novel passive waveshaping method for single-phase diode rectifiers is presented. It is shown that application of the proposed method maintains high-input power factor, lowers rectifier current stresses, and lowers the volt-ampere (VA) rating of the associated reactive components as compared to the standard diode rectifier. Relevant input and output current waveforms, component ratings, and power factor values are derived. Different modes of operation are discussed as a means of obtaining high performance. Key predictions, such as input/output waveforms and associated harmonic spectra, have been verified experimentally on a 1 kVA laboratory prototype unit 相似文献
14.
Active front-end rectifiers with reduced input current harmonics and high input power factor will be required in the near future for utility interfaced applications. In order to meet the new and more stringent regulations with force-commutated switches, the voltage source inverter approach is superior to the conventional current source approach, in terms of number of components and control options. However, the straightforward power angle control of the rectifier is characterized by a slow response and potential stability problems. This paper proposes a current-controlled PWM rectifier as an alternative. It provides near sinusoidal input currents with unity power factor and a low output voltage ripple. Moreover, it produces a well-defined input current harmonic spectrum, exhibits fast transient response to load voltage variations, and is capable of regenerative operation. PWM pattern generation is based on a carrier technique and the current controller is implemented in the: (a) stationary (abc) frame; and (b) rotating (dqo) frame. The design and the performance of the two controller options are investigated and compared 相似文献
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16.
《Electron Devices, IEEE Transactions on》2006,53(8):1922-1928
Loss of efficiency and tube oscillations have been attributed to electrons returning from the output cavity in klystrons due to excessive output cavity voltages. It is generally believed that the retrograde electrons lead to a relatively large harmonic current component in the input cavity, which overwhelms the input drive. Here, for the first time, detailed simulations describing the dynamics of retrograde particles for a nominal klystron design and cases with the shunt impedance of the output cavity increased, which show persistent harmonic bunching induced by the penultimate cavity, are presented. The maximum retrograde harmonic current is comparable to the current induced in the input cavity without the retrograde particles and can significantly influence the overall klystron behavior. 相似文献
17.
Fonderie J. Maris M.M. Schnitger E.J. Huijsing J.H. 《Solid-State Circuits, IEEE Journal of》1989,24(6):1551-1559
A bipolar operational amplifier (OA) with rail-to-rail input and output ranges which can operate at supply voltages down to 1 V is presented. At this supply voltage, the input offset voltage is typically 1.0 mV in an input common-mode voltage range that extends beyond both supply rails for about 300 mV, with a common-mode rejection ratio (CMRR) between 38 and 100 dB, depending on conditions. The output voltage can reach both supply rails within 100 mV, the output current is limited to ±10 mA, the voltage gain is 100 dB, and the bandwidth is 450 kHz. The die is 2.5×5.5 mm2. Qualities such as offset, input-bias current, and CMRR are improved when the supply voltage is increased and the dynamic level shift is autonomically turned off. The OA has been protected against unintentional reversal of the output signal when the inputs are substantially overdriven. The output stage of the circuit consists of two full complementary composite transistors, whose HF characteristics have been improved by internal Miller compensation and linearization of the transconductance 相似文献
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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 相似文献
20.
Klaassens J.B. Moize de Chateleux W.L.F.H.A. van Wesenbeeck M.P.N. 《Power Electronics, IEEE Transactions on》1988,3(2):164-173
A method of decreasing the ripple on the output voltage of high-power AC-DC or DC-DC series-resonant converters without increasing the internal converter frequency or the capacity of the energy storage elements is discussed. This improvement is accomplished by subdividing the converter into two or more series-resonant power modules operated with a constant relative phase shift (phase-staggering control). The method of eliminating the harmonic components in the input and output currents of the conversion system, without increasing the internal pulse frequency, is justified by Fourier analysis of the current waveforms. The frequency spectra of the source and output waveforms for the continuous and discontinuous resonant current mode are shifted to higher frequency ranges, as computations show for both one single module and multiple paralleled modules. Inadequacies in the phase-staggering control method applied to series-resonant converters are indicated in relation to the dominant harmonic component, in particular for two modules and supported by experimentally acquired waveforms. High-frequency current components to the source and to the load are reduced. Resulting in smaller input and output filters. This improves the resolution of the control of the flow of energy from the source to the load, resulting in a faster system response 相似文献