Showing papers on "PWM rectifier published in 1997"
TL;DR: A new three-phase three-switch three-level pulsewidth modulated (PWM) rectifier system is developed that can be characterized by sinusoidal mains current consumption, controlled output voltage, and low-blocking voltage stress on the power transistors.
Abstract: Based on the combination of a three-phase diode bridge and a DC/DC boost converter, a new three-phase three-switch three-level pulsewidth modulated (PWM) rectifier system is developed. It can be characterized by sinusoidal mains current consumption, controlled output voltage, and low-blocking voltage stress on the power transistors. The application could be, e.g., for feeding the DC link of a telecommunications power supply module. The stationary operational behavior, the control of the mains currents, and the control of the output voltage are analyzed. Finally, the stresses on the system components are determined by digital simulation and compared to the stresses in a conventional six-switch two-level PWM rectifier system.
509 citations
TL;DR: In this article, a new topology for a PWM rectifier which achieves unity power factor on the AC supply side and ripple reduction on the DC output side is presented. But it does not require a large DC capacitor or a passive LC resonant circuit.
Abstract: This paper presents a new topology for a pulsewidth modulation (PWM) rectifier which achieves unity power factor on the AC supply side and ripple reduction on the DC output side. The main circuit of this rectifier consists of a conventional PWM rectifier and a pair of additional switches. The switches and PWM rectifier are controlled such that the ripple current on the DC line is reduced, and unity power factor is achieved on the AC line. As a result, this circuit does not require a large DC capacitor or a passive LC resonant circuit. Furthermore, control of the additional switches and PWM rectifier requires only a simple control circuit. The effectiveness of this circuit was confirmed by experiments and analysis. The rectifier is useful for uninterruptible power systems (UPSs) and DC power supplies, especially for cases in which batteries are connected to the DC line.
175 citations
03 Aug 1997
TL;DR: A new voltage source inverter without DC link components, whose rectifiers are controlled by suitable current feedback to adjust near-sinusoidal AC source current waveforms at unity power factor is proposed.
Abstract: The voltage-source inverters are normally equipped with an electrolytic capacitor in their DC link, the electrolytic capacitor has several disadvantages such as increasing size, limiting converter life and reliability. Therefore several approaches for removing the DC link capacitor have been studied. This paper proposes a new voltage source inverter without DC link components, whose rectifiers are controlled by suitable current feedback to adjust near-sinusoidal AC source current waveforms at unity power factor. The calculated characteristics are described for a 0.75 kW induction motor driven by this inverter.
58 citations
22 Jun 1997
TL;DR: A novel PWM strategy which minimizes the loss of a voltage-fed three-phase PWM rectifier is developed from the following two factors: low switching frequency ratio and absence of switching in the vicinity of peak input current.
Abstract: In this paper, the conduction and switching losses of a three-phase PWM rectifier are analyzed for various PWM schemes. On the basis of these results, a novel PWM strategy which minimizes the loss of a voltage-fed three-phase PWM rectifier is developed. This minimization results from the following two factors: (a) low switching frequency ratio; and (b) absence of switching in the vicinity of peak input current. The effectiveness of the proposed PWM strategy is verified by both simulation and experimental results.
40 citations
Patent•
21 Apr 1997
TL;DR: In this article, switching losses are distributed equally between multiple switching devices in a rectifier bridge (50) in which the rectifier bridging comprises at least a first pair of serially connected switching devices (56A, 56B) connected between positive and negative DC output buses (52, 54) and a second pair of SUs connected in parallel with the first SUs.
Abstract: Switching losses are distributed equally between multiple switching devices in a rectifier bridge (50) in which the rectifier bridge comprises at least a first pair of serially connected switching devices (56A, 56B) connected between positive and negative DC output buses (52, 54) and a second pair of serially connected switching devices (58A, 58B) connected in parallel with the first pair of switching devices. Only one of the switching devices in each pair of switching devices is pulse width modulated at any time at a frequency substantially higher than a frequency of the AC power applied to the rectifier bridge while another of the switching devices in each pair of switching devices is operated in synchronism with the waveform of the AC power applied to the bridge. Operation further involves periodically alternating the PWM operation of the switching devices between switching devices in each pair of switching devices so as to distribute the losses. Preferably, the process of alternating between PWM modulated switching devices occurs at zero crossings of the AC waveform so as to minimize transience generated in the switching process.
36 citations
23 Feb 1997
TL;DR: In this article, the topology of a new three-phase three-switch three-level PWM rectifier system is derived based on the basic structure of a DC-to-DC SEPIC power converter.
Abstract: In this paper, the topology of a new three-phase three-switch three-level PWM rectifier system is derived based on the basic structure of a DC-to-DC SEPIC power converter. The system is characterized by full controllability of the power flow (independent of the level of the output voltage) and by a sinusoidal mains current shape in phase with the mains voltage. The operating principle of the power converter is explained based on the conduction states of a bridge leg within a pulse period. The stationary operating behavior is analyzed by digital simulation based on the control of the mains phase currents by independent ramp-comparison controllers. Furthermore, a mathematical description of the operating behavior of the three-phase system including the coupling of the phase current controllers (given due to the floating mains star point) is discussed. Finally, results of an experimental investigation of a laboratory model of the power converter are presented.
34 citations
Patent•
21 Apr 1997TL;DR: In this paper, the authors proposed a method and apparatus for reduction of radio frequency interference caused by rectifier switching devices (56A, 56B, 58A, 58B) in multiple rectifiers 50 connected to a common power source.
Abstract: A method and apparatus for reduction of radio frequency interference caused by pulse width modulation of rectifier switching devices (56A, 56B, 58A, 58B) in multiple rectifiers 50 connected to a common power source. In general, the invention reduces radio frequency signals introduced into the power source by phase shifting operation of the rectifiers such that one of the rectifiers has switching devices which are gated into conduction during a first portion of a pulse width modulation cycle and switching devices in another rectifier are gated into conduction during another portion of the pulse width modulation cycle. In this manner, switching of devices in one of the rectifiers produces harmonic currents during one portion of a PWM cycle while the switching devices in the second rectifier produce harmonic currents during another portion of the cycle. The phase shifting of the harmonic currents prevents the harmonics from adding together into larger amplitudes and thereby reduces the amplitude of the harmonics. The system is particularly useful in transit car operation in which multiple cars may be train lined together and respond to the same train commands to apply power to electric motors on each of the cars. In this instance, the switching devices in each of the rectifiers in each of the cars may be phase shifted to prevent summation of harmonic currents; or the rectifiers within each car, if multiple rectifiers are used in each car, may be phase shifted.
21 citations
TL;DR: In this paper, a method for controlling a single-phase rectifier without any voltage sensors is proposed, where the ac-side voltage can be estimated from the input-reactor voltage when the ac side of the bridge is short-circuited; the reactor voltage is easily obtained by multiplication of the inductance of the reactor and the derivative of the source current measured.
Abstract: Pulsewidth modulation (PWM) control techniques for rectifiers are widely used to improve the source current waveform and the input power factor. Recently, methods to reduce the number of detectors are studied to simplify system configuration of such rectifiers and their control. It is known that a voltage detector on the ac-side can be omitted though a voltage detector on the dc-side is needed for adjustment of the dc-output of a PWM rectifier.In this paper, a method for controlling a single-phase rectifier without any voltage sensors is proposed. The ac-side voltage can be estimated from the input-reactor voltage when the ac-side of the bridge is short-circuited; the reactor voltage is easily obtained by multiplication of the inductance of the reactor and the derivative of the source current measured. On the other hand, the dc-side voltage can be estimated by calculating the difference between the source voltage at the beginning of every switching period and the reactor voltage sampled and held in the previous bridge conduction mode.This paper describes the control scheme and its implementation, and performance characteristics of the rectifier. The usefulness of the rectifier is confirmed by experiment. The method is applicable to various types of PWM rectifiers.
14 citations
23 Feb 1997
TL;DR: In this paper, a control strategy based on combining modulation index and phase shift control is proposed to achieve near unity input displacement factor (IDF) for a wide range of operating points, including a description of the proposed control strategy, investigation of IDF compensation limitations, and simulation and experimental results for various modes of operation.
Abstract: The current source rectifier (CSR) operated with selective harmonic elimination (SHE) method with low switching frequencies (300-420 Hz) can meet stringent input harmonic requirements and is therefore, a suitable front end for medium voltage CSI based AC drives. Regulation of the DC link current can be achieved by either phase shifting the gating pattern or varying the modulation index. Both of these methods however, result in unacceptably low values of input displacement factor (IDF) for light loads. A control strategy based on combining modulation index and phase shift control is proposed in this paper to achieve near unity IDF for a wide range of operating points. The paper includes a description of the proposed control strategy, investigation of IDF compensation limitations, and simulation and experimental results for various modes of operation. The paper also investigates the IDF values for the above three control strategies and for three different types of industrial loads. Results show that depending on the speed/torque characteristics of the load, a power factor correction system may not always be necessary for CSI based drives with PWM rectifier front end.
13 citations
09 Nov 1997
TL;DR: In this article, a mathematical model of the DC link voltage control for a three-phase to threephase VSI-PWM rectifier and inverter systems with eight switches is presented.
Abstract: Three-phase to three-phase VSI-PWM rectifier and inverter systems with eight switches have many advantages: capability of unity or even leading power factor; sinusoidal input current waveforms; bidirectional power flow etc. This paper derives a mathematical model of the DC link voltage control for such a system. The transient model for overall and difference voltages of split capacitor DC link is developed, and typical simulated and experimental results for dynamic responses are presented to illustrate important performance characteristics to verify the developed model.
11 citations
09 Nov 1997
TL;DR: In this paper, the authors describe the development of a simulation model for an actual PWM power converter system being used in trains recently introduced to the suburban rail transport system in Brisbane, Australia.
Abstract: This paper describes the development of a simulation model for an actual PWM power converter system being used in trains recently introduced to the suburban rail transport system in Brisbane, Australia. The simulation model was developed as a teaching aid in modern traction drive technology for railway technical staff. The model is constructed using the SIMULINK graphical simulation platform. To enable modelling of the electric circuit, the dynamic node technique is employed. The simulation may run on any PC and is interactive, making it an excellent educational tool.
22 Jun 1997
TL;DR: In this paper, a comparative analysis and design procedure of a four-pole (eight switches) three-phase rectifier having a neutral point to the input filter capacitor is presented.
Abstract: This paper presents a comparative analysis and design procedure of a four-pole (eight switches) three-phase rectifier having a neutral point to the input filter capacitor. Space vector modulation (SVM) is developed for this PWM rectifier including the neutral path. This topology is compared with the conventional PWM rectifier using three poles (six switches). The proposed rectifier structure shows the advantages of low current harmonic injection, low output voltage ripple, and better control flexibility for continuous service in electric system with low power quality. The feasibility and features of the proposed four-pole three-phase rectifier is verified by simulation and experimental results.
07 Jul 1997
TL;DR: In this paper, the authors present a control method for current-type PWM rectifiers based on a space vector modulation technique adapted to current inverters and a simple and efficient damping system.
Abstract: This paper presents a control method for current-type PWM rectifiers. This method is based on a space vector modulation technique adapted to current inverters and a simple and efficient damping system. PWM current converters have the same characteristics and the same problems as the PWM rectifiers. These power converters uses LC filters on the AC side, and as a consequence, undesired oscillations take place. These oscillations are not dependent on the PWM technique used but depend on the LC filter size. A simple, cost-effective and efficient damping system is presented in this paper. This damping system uses the voltages across the AC inductors as feedback variables. The system is analysed with a simplified model and analytical expressions are presented to synthesise the feedback loop. The results presented shows excellent behaviour in steady-state and in transient regimes.
TL;DR: In this article, a novel topology of the PWM rectifier is presented to accomplish the reduction of the low frequency ripple current, a novel circuit is constituted by adding only a pair of switching devices to conventional PWM converter circuit.
Abstract: The generation of harmonics and their subsequent propagation into power line is a topic of increasing concern to power supply authorities. To prevent obstacles on the power system, Unity-Power-Factor PWM converter is going to apply to AC-DC power conversion plant. However, PWM converter, especially at single phase circuit, has some serious defects, that is low frequency ripple current which flows into the DC line and low frequency ripple voltage which appears on the DC output In usual case, it is necessary to connect a very large capacitor or a passive L-C resonant circuit to the DC line for the reduction of low frequency ripple voltage. However, in case of the Batteries are connected with the DC output, most of the DC ripple current flows into the Battery even if previous circuits are used because the impedance of the Battery is very low compared with that of previous circuit. The low frequency ripple current cause power loss on the Battery and the temperature has risen. It is well known that the life of the Battery is deeply influenced by the temperature. The ripple current, therefore, should be reduced to as possible as low.To accomplish the reduction of the low frequency ripple current, a novel topology of the PWM rectifier is presented in this paper. The main circuit is constituted by adding only a pair of switching devices to conventional PWM converter circuit. With simple control technique, the ripple energy on the DC line is converted into the stored energy on the input AC capacitors though the additional switches. The theoretical characteristics are obtained by using statespace-averaging-method. The effect of the ripple reduction is confirmed by experiments using a bread board set-up.
TL;DR: In this article, a method for controlling a single-phase rectifier without any voltage sensors is proposed, where the ac-side voltage can be estimated from the input-reactor voltage when the ac side of the bridge is short-circuited; the reactor voltage is easily obtained by multiplication of the inductance of the reactor and the derivative of the source current measured.
Abstract: Pulsewidth modulation (PWM) control techniques for rectifiers are widely used to improve the source current waveform and the input power factor. Recently, methods to reduce the number of detectors are studied to simplify system configuration of such rectifiers and their control. It is known that a voltage detector on the ac-side can be omitted though a voltage detector on the dc-side is needed for adjustment of the dc-output of a PWM rectifier.In this paper, a method for controlling a single-phase rectifier without any voltage sensors is proposed. The ac-side voltage can be estimated from the input-reactor voltage when the ac-side of the bridge is short-circuited; the reactor voltage is easily obtained by multiplication of the inductance of the reactor and the derivative of the source current measured. On the other hand, the dc-side voltage can be estimated by calculating the difference between the source voltage at the beginning of every switching period and the reactor voltage sampled and held in the previous bridge conduction mode.This paper describes the control scheme and its implementation, and performance characteristics of the rectifier. The usefulness of the rectifier is confirmed by experiment. The method is applicable to various types of PWM rectifiers.
03 Aug 1997
TL;DR: The performance of the PWM rectifier with the proposed control strategy is confirmed by experiments, where the transient dynamic response was greatly improved, and stability analysis to determine optimum values of feedback gains is reported.
Abstract: A new control method for voltage type PWM AC to DC converters with reduced number of sensors is proposed. To reduce the waveform distortion and DC offset current of the supply current, state feedback control of the LC filter in the AC side is used. Analysis of the current control system, and stability analysis to determine optimum values of feedback gains are reported, The performance of the PWM rectifier with the proposed control strategy is confirmed by experiments, where the transient dynamic response was greatly improved.
07 Jul 1997
TL;DR: In this article, a connection controller is proposed to control a three-phase voltage-source controlled-current PWM rectifier, based on a particular analysis of dependencies between the switch states and the resulting converted electrical quantities.
Abstract: A particular analysis of dependencies between the switch states and the resulting converted electrical quantities is detailed in this paper. By using a nonlinear inversion of these relations, we deduce a connection controller which enables the proper control of modulated electrical variables. This method is then used to control a three-phase voltage-source controlled-current PWM rectifier. The generality of the proposed method points out the unification of this design to matrix converters of any dimension.
18 May 1997
TL;DR: A new software-based space vector control strategy, which can be used to convert a standard U/f-controlled motor inverter to work as a high performance PWM rectifier, is presented.
Abstract: The benefits of the PWM rectifier compared to diode rectifiers are outlined for AC motor drive applications A new software-based space vector control strategy, which can be used to convert a standard U/f-controlled motor inverter to work as a high performance PWM rectifier, is presented The operation is verified with a series produced industrial inverter
07 Jul 1997
TL;DR: In this paper, a comparative analysis and design procedure of a four-pole (eight switches) three-phase rectifier having a neutral point to the input filter capacitor is presented, where different space vector modulation (SVM) strategies are proposed for this PWM rectifier including the neutral path.
Abstract: This paper presents a comparative analysis and design procedure of a four-pole (eight switches) three-phase rectifier having a neutral point to the input filter capacitor. Different space vector modulation (SVM) strategies are proposed for this PWM rectifier including the neutral path. This topology is compared with the conventional PWM rectifier using three poles (six switches). The proposed rectifier shows the advantages of low current harmonic injection, low output voltage ripple and a feature of variable structure to achieve continuous service when it is powered from a utility with low power quality. The feasibility of the proposed four-pole three-phase rectifier is verified by simulation and experimental results.