Showing papers on "PWM rectifier published in 2001"

Comparative evaluation of modulation methods for a three-phase/switch buck power factor corrector concerning the input capacitor voltage ripple

Abstract: For a three-phase three-switch buck-type PWM rectifier with unity power factor, the RMS value of the input filter capacitor voltage ripple is calculated for different modulation methods. A modulation method being optimal concerning the occurring switching losses and the RMS value of the capacitor voltage ripple is identified and guidelines for the dimensioning of the input filter are derived.

Four-step commutation strategy of PWM rectifier of converter without DC link components for induction motor drive

Abstract: In this paper, we describe a method of generating gate signals of the PWM rectifier section of the converter without DC link components, which is able to remove snubber circuits In the snubber circuits, losses have been dissipated every time the switches of the rectifier section are turned on and off The commutation strategy of the proposed method consists of four steps during the switching process The proposed method is verified by experimental tests on an induction motor drive It is concluded that it decreases losses in the rectifier section

Bi-directional AC/DC converter based on neutral point clamped

Abstract: A single-phase bi-directional AC/DC converter based on neutral point diode clamped configuration is proposed to draw a clean sinusoidal line current with nearly unity input power factor and to achieve DC bus voltage regulation. Based on the neutral point diode clamped scheme, the voltage stress of the power devices is clamped to half DC bus voltage instead of full DC link voltage in the conventional half and full bridge PWM rectifier. The line current command tracking, voltage regulation and balanced neutral point voltage are performed by the inner loop current controller, the outer loop voltage controller and voltage balance compensator, respectively. To generate a three-level PWM pattern on the AC terminal of the AC/DC converter, a region detector of the mains voltage is employed. The effectiveness of the proposed control scheme is confirmed by the experimental results.

Suppression of common-mode voltage in a PWM rectifier/inverter system

Abstract: This paper proposes a PWM rectifier/inverter system capable of suppressing not only supply harmonic currents but also electromagnetic interference (EMI) An active common-noise canceler (ACC) developed for this system is characterized by sophisticated connection of a common-mode transformer which can compensate for common-mode voltages produced by both PWM rectifier and inverter As a result, the size of the common-mode transformer can be reduced to 1/3, compared with the previously proposed ACC A prototype PWM rectifier/inverter system (22 kW) has been implemented and tested Some experimental results show reduction characteristics of the supply harmonic current and EMI

A novel concept for mains voltage proportional input current shaping of a VIENNA rectifier eliminating controller multipliers. I. Basic theoretical considerations and experimental verification

Abstract: Part I of 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 PWM (VIENNA) rectifier system. Furthermore, the concept features a low input current ripple amplitude as, e.g., achieved for space vector modulation, a low amplitude of the 3rd 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 PWM 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 and therefore is ideally suited as a basis for the development of an integrated control circuit for three phase power factor correction is presented.

A unity-power-factor buck-type PWM rectifier for medium/high-power DC motor drive applications

Abstract: This paper describes the application of a single-stage unity-power-factor buck-type pulsewidth modulation (PWM) rectifier to medium- and high-power variable-speed dc motor drives. The advantages of the developed system are low harmonic distortion in AC supply currents (complying with IEEE Std. 519 and IEC 555), nearly unity power factor over a wide operating shaft speed range, and nearly level armature current and voltage waveforms. These properties of output voltage and current quantities of the converter eliminate entirely any failure risk in current commutation even for oldest motor designs, and further motor problems such as accelerated aging in motor insulation, and mechanical failure due to circulating bearing currents. The design criteria and operating features and characteristics of the buck-type PWM rectifier employed in a unity-power-factor DC motor drive are discussed in the paper. The performance of the resulting system has been tested on 25-65-kW 100-150-A 10-20-kHz DC motor drives, used in various processes of an iron and steel plant.

Design of a novel multi-chip power module for a three-phase buck+boost unity power factor utility interface supplying the variable voltage DC link of a square-wave inverter drive

Abstract: The power semiconductors of one bridge leg of the buck-type input stage of a three phase buck+boost PWM rectifier are integrated into a novel power module. The basic function of the rectifier system is described, and the current stresses on the power semiconductors are calculated analytically. By an experimental analysis of the module, the switching losses of the power transistors are determined, and the system efficiency and the loss contributions of the different components are calculated. This gives a basis for the selection of advantageous operating parameters of the module in an industrial application.

Experimental analysis of a 5 kW wide input voltage range three-phase buck+boost power factor corrector

Abstract: In this paper the experimental analysis of a three-phase three-switch buck+boost PWM rectifier with unity power factor is discussed. The output voltage and the output current control are realized using a digital signal processor where a modulation scheme is employed which does provide minimum switching losses and minimum input capacitor voltage ripple rms value. The control design which is based on an equivalent DC/DC converter and state-space averaging is discussed briefly. Finally, the efficiency, the power factor, and the total harmonic distortion and the low-frequency harmonics of the mains current are gained in dependency on the output power by measurements on a 5 kW prototype of the system.

A new low-frequency state model of a three-phase three-switch three-level fixed-frequency PWM rectifier

Abstract: This paper presents a new dynamic model of a three-phase, three-switch, three-level, fixed-frequency Pulse-Width-Modulated (PWM) rectifier. The modeling approach uses the state-space averaging technique in continuous current mode. The averaging process is applied on two time intervals: the switching period for average current evaluation, and the mains period for average voltage computation. A basic mathematical model of the converter is first established. A simplified time-invariant model is then deduced using rotating Park transformation. The steady-state regime is analyzed on the basis of the obtained model, and converter design criteria are consequently discussed. Numerical simulations are carried out in order to demonstrate the effectiveness of the proposed modeling approach.

Common mode current reduction method

Abstract: PROBLEM TO BE SOLVED: To reduce a common mode current applied to a power converter comprising a PWM rectifier circuit and a PWM inverter circuit at a low cost. SOLUTION: Semiconductor devices Q 1 , Q 3 , and Q 5 of a PWM rectifier circuit and semiconductor devices Q 7 , Q 9 , and Q 11 of a PWM inverter circuit are simultaneously turned on (or off) or, semiconductor devices Q 2 , Q 4 , and Q 6 of the PWM rectifier circuit and semiconductor devices Q 8 , Q 10 , and Q 12 of the PWM inverter circuit are simultaneously turned off (or on) to reduce a change of a common mode voltage and hence reduce a common mode current. As a result, the dimensional reduction of a common mode filter and the dimensional reduction of a cooler of a common mode current suppressor can be realized, so that the cost can be reduced. COPYRIGHT: (C)2003,JPO

A low-cost system of variable-speed cascaded induction generators for small-scale hydroelectricity

Abstract: A novel variable-speed cascaded induction generator system is proposed for small-scale hydroelectric power plants, in which the second induction generator has double three-phase stator windings (or six-phase windings) The proposed low-cost system can provide a brushless, robust structure and less distorted currents without using an expensive PWM rectifier on the machine side and an expensive adjustable-blade water turbine The simulated results showed that the system has sufficient capabilities for practical use

A PWM Rectifier/Inverter System Being Capable of Suppressing Both Harmonics and EMI

Abstract: A PWM Rectifier/Inverter System Being Capable of Suppressing Both Harmonics and EMI Satoshi Ogasawara, Member, Masato Fujikawa, Student Member (Okayama University), Hirofumi Akagi, Member (Tokyo Institute of Technology) This paper proposes a new PWM rectifier/inverter system that is capable of suppressing not only supply harmonic currents but also electromagnetic interference (EMI). The conversion system consists of a PWM rectifier and inverter, and an active common-noise canceler (ACC) which has been proposed by the authors. The ACC developed for this system is characterized by sophisticated connection of a common-mode transformer which can compensate for common-mode voltages produced by both the PWM rectifier and inverter. As a result, the size of the common-mode transformer can be reduced to 1/3, compared with the previously proposed ACC. A prototype PWM rectifier/inverter system (2.2 kW) has been implemented and tested. Some experimental results show reduction characteristics of the supply harmonic current and EMI.

Source-voltage-sensorless scheme for PWM rectifier under voltage unbalance condition

Abstract: A simple and robust source-voltage-sensorless scheme for a PWM rectifier considering voltage unbalance conditions is proposed. When a voltage unbalance occurs in a three-phase system, the unbalance component deteriorates the performance of the voltage source estimator by generating AC disturbances. Since the the source voltage information is used to control the real/reactive power flow, the inaccurate information causes voltage fluctuation in the DC-link, the increase of reactive power, and furthermore, instability in a PWM rectifier. In this work, the proposed sensorless scheme estimates the normal components and the unbalance components of the source voltage separately by using a modified reduced-dimensional estimator. The use of the measurement's derivative quantity sensitizing the estimator to measurement noises is avoided by introducing an auxiliary variable. Thus, the proposed sensorless scheme yields better robustness to measurement noises, and it works well even in the transient state. The feasibility of the proposed sensorless scheme is confirmed through computer simulations and experiments.

A high-efficiency soft switching zero-voltage-transition converter using combined inductor energy recovery circuits

Abstract: This paper presents a novel single-phase high power factor soft switching PWM rectifier, featuring soft commutation of the main and auxiliary switches using a simplified combined inductor energy recovery circuit. Conventional soft switching PFC circuits require both a boost inductor and an additional transformer separately to achieve soft switching and energy recovery. In this paper, these two devices are combined together as one unit. The combined inductor with simple additional winding can work as a boost inductor and an auxiliary inductor at the same time. The input current shaping is achieved with average current mode, and continuous inductor current mode control. Principle of operation, theoretical analysis, a design example and experimental results from a laboratory prototype rated 2 kW with 400 VDC output voltage are presented. The measured efficiency and power factor were 97.63% and 0.998 respectively with an input current THD less than 2.5%. Thus the proposed topology can reduce the number of devices in the circuits while achieving high efficiency.

An improved output short-circuit protection for multilevel PWM rectifier

Abstract: This paper describes an improved short-circuit protection method with a boost type rectifier using a multilevel AC/DC power converter. Since the output DC capacitors of the proposed scheme have ability to keep a floating state, the DC capacitors do not discharge even in case of short-circuit of a DC load. The output DC power of the proposed converter can be disconnected from the load within several hundred microseconds at the instant of short-circuit fault. Once the fault has been cleared the DC power is reapplied to the load. The rising time of the DC load voltage is as small as several hundred microseconds, and there is no overshoot of the DC voltage because the DC output capacitors hold undischarged state. Therefore, the proposed converter can be used for a power supply, which requires a rapid disconnection of the load from the power supply in the case of a short circuit, as well as a rapid connection the load to the power supply after the clearance of the short circuit condition. The converter, which employs the proposed method, has the characteristics of a simplified structure, reduced cost, weight, and volume compared with a conventional power supply, which has frequent output short-circuits. Experimental results are presented to verify the usefulness of the proposed converter.

A new high-efficiency zero-voltage-switching AC-DC boost converter using energy recovery circuits

Abstract: This paper presents a novel single-phase high power factor soft switching PWM rectifier, featuring soft commutation of the main and auxiliary switches using a simplified combined inductor energy recovery circuit. In conventional soft switching PFC circuits, both a boost inductor and an additional transformer are required separately to achieve soft switching and energy recovery. In this paper, the two devices are combined as one unit. The combined inductor with simple additional winding can work as a boost inductor and an auxiliary inductor at the same time. The input current shaping is achieved with average current mode, and continuous inductor current mode control. Principle of operation, theoretical analysis, a design example, and experimental results from a laboratory prototype rated 2 kW with 400 VDC output voltage are presented. The measured efficiency and power factor were 97.63% and 0.998 respectively with an input current THD less than 2.5%. Thus the proposed topology can reduce the number of devices in the circuits while achieving high efficiency.

Sliding mode control of neutral point clamped PWM rectifier

Abstract: A sliding mode controlled single-phase neutral point clamped rectifier is proposed to achieve bi-directional power flow, regulate dc bus voltage, reduce line current distortion and obtain nearly unity power factor. Based on the neutral point clamped topology, the voltage stress of the power devices is clamped to half dc bus voltage instead of full dc link voltage in the conventional PWM rectifier. The line current tracking, dc link voltage regulation and neutral point voltage compensation are performed by the inner loop current controller, the outer loop voltage controller and voltage balance compensator, respectively. Based on the proposed control scheme, the rectifier can draw a clean sinusoidal line current with unity input power factor. The experimental results are presented to verify the effectiveness of the proposed control scheme.

A single-phase capacitor clamped converter operated simultaneously as a PWM rectifier and an active power filter

Abstract: A control scheme is proposed that employs an active rectifier to work simultaneously as an active power filter to decrease current harmonics. The adopted capacitor clamped rectifier is controlled to draw a sine wave line current with low current harmonics. A voltage controller, three capacitor voltage compensators and one current controller are used in the proposed control algorithm to achieve a constant DC bus voltage, balanced capacitor voltages and line current tracking. The validity of the proposed system is proved by the results of computer simulations and experimental tests.

Transformer Parasitic Inductor and Lossless Capacitor-Assisted Soft-Switching DC-DC Converter with Synchronous Phase-Shifted PWM Rectifier with Capacitor Input Filter

Abstract: This paper presents a new prototype of soft-switching DC-DC power converter with a high frequency transformer link which has two active power controlled switches in full bridge rectifier with capacitor input type smoothing filter. In this DC-DC converter, ZVS of the inverter in transformer primary side and ZCS of active rectifier area in secondary side can be completely achieved by taking advantage of parasitic inductor component of high-frequency transformer and lossless snubbing capacitors. Its operation principle and salient features are described. The steady-state operating characteristics of the proposed DC-DC power converter are illustrated and discussed on the basis of the simulation results in addition to the experimental ones obtained by 2kw-40kHz power converter breadboard set up.

A Transformerless Cascade Multilevel PWM Rectifier with Unity Power Factor

Abstract: This paper presents a cascade multilevel PWM rectifier without the isolation transformers for energy build-up at each inverter modules. The features and advantages of the proposed PWM rectifier can be summarized as follows; 1) It realizes the high power high voltage AC/DC power conversion, 2) It uses no transformer which is bulky and heavy, 3) It has hybrid structure so that switching devices can be effectively utilized, 4) It produces high quality AC current even in high power high voltage applications, 5) The input power factor remains unity by simple modulation index control. The multilevel rectifier is analyzed by using the circuit DQ transformation whereby the characteristics and control equations are obtained Finally, it will be shown that the system simulation reveals the validity of analyses.