Showing papers on "Rectifier published in 2001"

Design and control of an LCL-filter-based three-phase active rectifier

Abstract: This paper proposes a step-by-step procedure for designing the LCL filter of a front-end three-phase active rectifier. The primary goal is to reduce the switching frequency ripple at a reasonable cost, while at the same time achieving a high-performance front-end rectifier (as characterized by a rapid dynamic response and good stability margin). An example LCL filter design is reported and a filter has been built and tested using the values obtained from this design. The experimental results demonstrate the performance of the design procedure both for the LCL filter and for the rectifier controller. The system is stable and the grid current harmonic content is low both in the lowand high-frequency ranges. Moreover, the good agreement that was obtained between simulation and experimental results validates the proposed approach. Hence, the design procedure and the simulation model provide a powerful tool to design an LCL-filter-based active rectifier while avoiding trial-and-error procedures that can result in having to build several filter prototypes.

A novel control method for input output harmonic elimination of the PWM boost type rectifier under unbalanced operating conditions

Abstract: This paper presents a new control strategy to improve the performance of the PWM boost type rectifier when operating under an unbalanced supply. An analytical solution for harmonic elimination under unbalanced input voltages is obtained resulting in a smooth (constant) power flow from AC to DC side in spite of the unbalanced voltage condition. Based on the analysis of the open loop configuration, a closed loop control solution is proposed. Simulation results show excellent response and stable operation of the new rectifier control algorithm. A laboratory prototype has been designed to verify the discussions and analyses done in this paper. Theoretical and experimental results show excellent agreement. Elimination of the possibility of low order AC and DC side harmonics due to unbalance is expected to materially affect the cost of DC link capacitor and AC side filter. The proposed method is particularly useful in applications where the large second harmonic at the DC link may have a severe impact on system stability of multiply connected converters on a common link.

A simplified functional simulation model for three-phase voltage-source inverter using switching function concept

Abstract: In this paper, a functional simulation model for the voltage-source inverter (VSI) using the switching function concept is studied and the actual implementation of the model is proposed with the help of Matlab Simulink. Also, this concept is extended to the voltage-doubler-type pulse width-modulated (PWM) AC-DC rectifier and the PWM AC-DC-AC converter. With the developed functional model, the simplification of the static power circuits can be achieved so that the convergence and long run-time problems can be solved. Also, in the functional model, the design parameters, such as voltage and current ratings of the power semiconductor switches and load current, can be easily calculated. The general switching function concept is reviewed in brief and the proposed functional models for the VSI, voltage-doubler rectifier, and PWM AC-DC-AC converter and their implementations using Matlab Simulink are explained in detail. Also, several informative simulation results verify the validity of the proposed models.

A multimodule parallelable series-connected PWM voltage regulator

Abstract: This paper presents the analysis and design of a single-phase voltage regulator (VR) and its multinodule parallel control. The VR employs the pulsewidth modulation three-arm rectifier-inverter topology. The inverter side adjusts the load voltage with the series regulating structure aiming to minimize converter capacity and attain higher efficiency. The rectifier side regenerates the load power and executes the active power filter function to achieve unity power factor. Based on such high-performance VR, a resistive droop method combined with the P-V droop and Q-/spl delta/ shift scheme is then proposed to control the current sharing such that multiple VRs can be paralleled directly without any control interconnection. The proposed parallel control technique possesses the features of fast response, precise voltage regulation, equal fundamental and harmonic current sharing, tolerance for parameter mismatch, and so on. Two prototype 1 KVA VRs are implemented, and the effectiveness is demonstrated by some simulation and experimental results.

Power convertor with low loss switching

Abstract: A welding power supply includes an input rectifier that receives sinusoidal or alternating line voltage and provides a rectified voltage. A pre-regulator provides a dc bus and a convertor, such as a boost convertor, provides a welding output. The pre-regulator is an SVT (slow voltage transition) and an SCT (slow current transition) switched convertor. It may include a snubber circuit having a diode that is SVT switched. Also, the boost convertor may be SVT and SCT switched. The pre-regulator preferably includes a power factor correction circuit. The power source includes, in one embodiment, an inverter having a snubber circuit having a first switch in anti-parallel with a first diode, and a second switch in anti-parallel with a second diode. The first switch and first diode are connected in series with the second switch and the second diode, and the first and second switches are connected in opposing directions, to form a switched snubber.

Evaluation of input current in the critical mode boost PFC converter for distributed power systems

Abstract: This paper presents the analysis and evaluation of the input current in the critical mode single-phase boost power-factor-correction (PFC) converter. First, the switching-frequency ripple of the input current is derived and the differential-mode EMI filters of the critical and continuous mode PFC rectifiers are calculated and compared. Next, the benefits and challenges of interleaving the critical mode PFC rectifiers are discussed. Finally, the low-frequency input current distortions are analyzed with respect to the switching-frequency limits of the critical mode boost PFC rectifier.

Method And Apparatus For Receiving A Universal Input Voltage In A Welding Power Source

Abstract: A method and apparatus for providing a welding current is disclosed. The power source is capable of receiving any input voltage over a wide range of input voltages and includes an input rectifier that rectifies the ac input into a dc signal. A dc voltage stage converts the dc signal to a desired dc voltage and an inverter inverts the dc signal into a second ac signal. An output transformer receives the second ac signal and provides a third ac signal that has a current magnitude suitable for welding. The welding current may be rectified and smoothed by an output inductor and an output rectifier. A controller provides control signals to the inverter and an auxiliary power controller that can receive a range of input voltages and provide a control power signal to the controller.

Power supply apparatus for ARC-utilizing apparatuses

Abstract: One of commercial AC voltages is coupled to power supply terminals from one of commercial AC power supplies The AC power supplies belong to either a first group providing higher voltages or a second group providing lower voltages A rectifier rectifies the AC voltage applied to the power supply terminals, and a rectified voltage is developed between two rectifier output terminals A switching unit operates to connect voltage-boosting converters selectively in series and in parallel between the rectifier output terminals Inverters are connected in the output sides of and in association with the respective voltage-boosting converters for converting DC voltages from the associated voltage-boosting converters to high-frequency voltages The high-frequency voltages are voltage-transformed by associated voltage-transformers, and the voltage-transformed high-frequency voltages are converted into a DC voltage by a rectifier circuit and a reactor The DC voltage is developed between output terminals of the apparatus A switching control unit controls the switching unit so as to connect the voltage-boosting converters in series between the rectifier output terminals when a commercial AC power supply of the first group is connected to the power supply terminals, while connecting the voltage-boosting converters in parallel between the rectifier output terminals when a commercial AC power supply of the second group is connected to the power supply terminals

Modular structure of an apparatus for regulating the harmonics of current drawn from power lines by an electronic load

Abstract: Modular apparatus for regulating the harmonics of current drawn from power lines by electric equipment, comprising a first rectifier circuit module, consisting of an array of rectifying diodes; a second Switch and Controller Assembly (SCA) module, which comprises a power switch and controller and their interconnections; an input inductor for filtering the current drawn from the rectifier module; and an output capacitor, for filtering the output voltage ripple at the load. The inlet of the rectifier is connected to the power line and an outlet of the rectifier module is connected to the SCA. The inlet of said SCA is connected to the rectifier, via an inductor and the outlet of said SCA is connected to the output capacitor. The inlet of the inductor is connected to the rectifier, the outlet of the inductor is connected to the inlet of said SCA, and the capacitor is connected in parallel with the load.

Three-phase PWM boost-buck rectifiers with power-regenerating capability

Abstract: Three-phase pulsewidth-modulated (PWM) boost-buck rectifiers with power-regenerating capability are investigated. The converters under consideration are capable of: (1) both voltage step-up and step-down; (2) bidirectional power processing; and (3) almost unity-power-factor operation with nearly sinusoidal AC current. Expected advantages are: (1) applicability to lower voltage applications, e.g., direct retrofit to replace diode or thyristor rectifiers; (2) switching loss reduction in the inverter load; (3) low-order harmonic control in the inverter load output voltage; (4) blanking time effect mitigation in the inverter load; and (5) a modest level of voltage sag/swell compensation. In this paper, firstly, a step-by-step power stage derivation process is described. Then, taking the Cuk-Cuk realization as an example, its operating principle and modulation scheme are described. A steady-state model and dynamic model for controller design are also described. Representative results of circuit simulations and hardware experiments are presented. Through these procedures, the feasibility of the presented three-phase PWM boost-buck rectifier with power-regenerating capability is demonstrated.

Electrochemical conversion system

Abstract: An electrochemical conversion system (110) is disclosed having a housing (111) defining an opening (112) and an internal chamber (113). An electrochemical cell (116) is mounted within the opening (112) which is electrically coupled to a circuit (117). The circuit (117) includes a load (127) and a battery (128) electrically coupled in series. The system may also be adapted to generate DC power with the addition of a rectifier.

A three-phase soft-transition inverter with a novel control strategy for zero-current and near zero-voltage switching

Abstract: This paper proposes a new soft-transition control strategy for a three-phase zero-current-transition (ZCT) inverter circuit. Each phase leg of the inverter circuit consists of an LC resonant tank, two main switches, and two auxiliary switches. The proposed strategy is realized by planning the switching patterns and timings of these four switches based on the load current information. It enables all the main switches and auxiliary switches to be turned on and turned off under zero-current conditions, and achieves a near zero-voltage turn-on for the main switches. Compared with existing ZCT strategies, the diode reverse recovery current and switching turn-on loss are substantially reduced, the current and thermal stresses in the auxiliary devices are evenly distributed over every switching cycle, and the resonant capacitor voltage stress is reduced from twice the DC bus voltage to 1.3-1.4 times the DC bus voltage. The proposed strategy is also suitable for three-phase power-factor-correction (PFC) rectifier applications. The operation principles, including a detailed analyst based on the state-plane technique, and a design rule are described in this paper. The circuit operation is first verified by a computer simulation, and is then tested with a 50-kW three-phase inverter to the full power level together with a three-phase induction motor in a closed-loop speed/torque control. Significant reductions in switching losses and voltage/current stresses over existing techniques have been experimentally demonstrated.

Alternator control circuit and related techniques

Abstract: An alternator system having an alternating current (ac) voltage source includes a switched-mode rectifier (SMR) coupled to the ac voltage source and having an output port coupled to an output of the alternator system, and a controller coupled to said switched-mode rectifier so as to provide a controlled pulse sequence synchronized with an angular rotor position of the (ac) voltage source to activate and deactivate the switched-mode rectifier The controller further includes a PWM generator having a first input to receive a total duty ratio signal synchronized with an angular rotor position of the (ac) voltage source The switched mode rectifiers are controlled to increase power output levels at lower speeds near idle The controller combines improved idle speed power output levels with load matching improvements from PWM control for more efficient operation when compared to circuits using conventional control or PWM load matching control alone

Operation of InGaAs/InP-Based Ballistic Rectifiers at Room Temperature and Frequencies up to 50 GHz

Abstract: Novel semiconductor rectifiers based on ballistic electron transport are fabricated from a high electron-mobility InGaAs/InP wafer. Because the device sizes are sufficiently small, operations at room temperature are achieved. Furthermore, the devices are shown to work not only at least up to 50 GHz but also with a sensitivity roughly the same as commercial microwave diodes, despite the fact that the devices have not yet been optimized. Aspects of using the devices in microwave applications are discussed in terms of the physical mechanism of the novel rectifying effect.

Switching power supply

Abstract: A switching power supply which includes a sychronous rectifier circuit that performs sychronous rectification with a main switching element by using rectifying switching elements. When a current begins to flow into the rectifying switching element 6, the rectifying switching element 6 builds up rapidly by the voltage induced in the auxiliary winding 21 of low impedance. Accordingly, the rectifying switching element 6 turns on rapidly at a point showing an approximately maximum current so that the ON-state resistance of the rectifying switching element 6 can be smaller. The voltage induced in the auxiliary winding 21 is fed directly as a drive signal of the rectifying switching element 6 so that the drive signal is not influenced by an output voltage.

Fail-safe leak detection and flood prevention apparatus

Abstract: A fail-safe leak detection and flood prevention apparatus includes an induced current, transconductive darlington amplifier and tuned-frequency standing water detector mounted at a lowest point of a potential leak plane for sensing variations of standing water conditions on the potential leak plane, and an induced current amplifier in communication with the standing water detector. A sensitivity control device for controlling sensitivity of the standing water detector for humidity, or dampness, level and for detecting a standing water leak; the sensitivity control device being in communication with the induced current amplifier. A latching relay driver connected to the sensitivity control device with the latching relay driver being able to memorize a leak condition when electrical power is lost. A control rectifier driven by the latching relay driver, with the control rectifier driving a 120-volt AC line voltage load. A normally closed 120-volt AC line operated fail-safe water cutoff device is connected with the control rectifier, so that when the standing water detector becomes wet, the induced current generated by the standing water detector changes the transconductance of the input darlington amplifier causing the induced current amplifier to indicate the leak condition, which removes electrical power from the normally closed 120-volt AC line operated fail-safe water cutoff device for shutting off water flow.

A full-wave rectifier using a current conveyor and current mirrors

Abstract: The realization of a full-wave rectifier using a current conveyor and current mirrors is presented. The proposed rectifier is composed of a voltage-to-current converter, a current mode full-wave rectifier, and a current-to-voltage converter. A voltage input signal is changed into a current signal by the voltage-to-current converter. The current mode full-wave rectifier rectifies this current signal resulting in the current full-wave output signal that is converted into a voltage full-wave output signal by one grounded-resistor. The theory of operation is described. The simulation and experiment results are used to verify the theoretical prediction. Simulated results show that the proposed rectifier yields the minimum voltage rectification to 94µV. Experimental results demonstrate the performance of the proposed rectifier for 50mVpeak signal rectification.

An integrated DC link choke for elimination of motor common-mode voltage in medium voltage drives

Abstract: An integrated DC link choke with common-mode voltage suppression is proposed for use in medium voltage (2300 V-7200 V) induction motor drives. The choke has an integrated magnetic core on which both differential and common-mode windings are placed. The differential winding is used to reduce the DC link current ripple while the common-mode winding is employed to suppress the motor common-mode voltage generated by the rectifier and inverter. The operating principle of the integrated DC choke is introduced. The calculation of the differential and common-mode inductances is presented. Experimental results based on a 5 hp induction motor drive are provided. A special issue concerning common-mode LC resonances is investigated. It is demonstrated that the proposed choke can be used to replace the isolation transformer normally used in medium voltage drives for common-mode voltage elimination, resulting in significant cost savings.

A generalized control method for input-output harmonic elimination for the PWM boost rectifier under simultaneous unbalanced input voltages and input impedances

Abstract: Under severe fault conditions in the distribution system, not only input voltages, but also input impedances must be considered as unbalanced. This paper presents a new control method for input-output harmonic elimination of the PWM boost type rectifier under conditions of both unbalanced input voltages and unbalanced input impedances. The range of unbalance in both input voltages and input impedances, for which the proposed method is valid, is analyzed in detail. An analytical approach for complete harmonic elimination shows that PWM boost type rectifier can operate at unity power factor under extreme unbalanced operating conditions resulting in a smooth (constant) power flow from AC to DC side. Based on the analyses in the open loop configuration, a feed-forward control method is proposed. Elimination of harmonics at AC and DC side of the converter affects the cost of DC link capacitor and AC side filter. The proposed method is very useful when PWM boost type rectifier is subject to extreme unbalance due to severe fault conditions in the power system. In addition, by using the proposed method, the PWM boost type rectifier can be operated from the single-phase supply in cases where three-phase source is not available. Simulation results show excellent response and stable operation of the PWM boost type rectifier under the proposed control algorithm.

Control loop and method for variable speed drive ride-through capability improvement

Abstract: A variable speed drive (VSD) having a rectifier, an inverter, an inverter modulator, an inverter controller, and a control loop, for controlling a motor load, wherein the control loop reduces an amount of power transferred to the inverter during a voltage sag. The control loop may include a reference generator, a filter, a regulator, and a ride-through corrective algorithm. A method for controlling a VSD to improve voltage sag ride-through by monitoring a voltage applied to the VSD, generating a control signal representative of losses in a motor load when a voltage sag is detected in the voltage applied to the VSD and applying less power to the load of the inverter.

Method and apparatus for a Reduced parts-counts multilevel rectifier

Abstract: A method and apparatus for a multilevel rectifier with fewer switching components is provided. The method reduces the required number of switching devices in an n level switching device and clamp diode rectifier. The method is valid for any positive integer number of levels equal to or greater than three. The method is also applicable to any phase system. The method reduces the number of switching devices required for an n-level rectifier from the standard 2(n−1) by 2 switching devices for every phase leg. A multilevel uni-directional power converter system including a multilevel rectifier that has a reduced number of switching devices is provided. The system comprises an input to a multilevel rectifier with at least one phase leg. The rectifier is composed of switching device and anti-parallel diode pairs and clamping diodes. The number of switching devices required depends on the given number of voltage levels according to the equation 2(n−1) where n is the number of voltage levels. This number of required devices is then reduced in accordance with the present invention by removing the top and the bottom switching devices from the rectifier circuit. The anti-parallel diodes remain in the rectifier circuit. There is no performance degradation from this reduction in the number of switching devices to the rectifier.

Comparative theoretical and experimental evaluation of bridge leg topologies of a three-phase three-level unity power factor rectifier

Abstract: In this paper a theoretical and experimental analysis of the voltage stress on the power semiconductors employed in a bridge leg of a unidirectional three-phase three-level PWM (VIENNA) rectifier is given. Furthermore, a new turn-on snubber is proposed which does improve the rectifier efficiency by 0.3% as verified by an experimental analysis and a detailed loss breakdown.

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

Synchronous bridge rectifier

Abstract: The present invention provides a synchronous full-wave AC rectifier connectable to an AC voltage source. In one embodiment, the synchronous rectifier includes a full-wave diode bridge having four bridge diodes. A power switch is coupled in parallel with each bridge diode, and each power switch has a power switch control gate. A power switch control circuit is coupled in parallel with each bridge diode. Each power switch control circuit provides a first control voltage to its associated power switch control gate to cause the power switch to turn on when the parallel-connected bridge diode is forward biased. Each power switch control circuit provides a second control voltage to its associated power switch control gate to cause the power switch to turn off when the parallel-connect bridge diode is reverse biased. The power switch control circuits turn their associated power switches on and off synchronously with the AC voltage source to provide the full-wave rectified AC output.

Voltage regulator for alternator and method of controlling power generation of alternator

Abstract: In an alternator, failure in a power supply line connected to an output terminal of a rectifier is detected. Upon detection of a failure in this power supply line, power generation is suppressed for a predetermined period that is longer than the time constant of a field winding of the alternator. Preferably, a high voltage pulse is detected to discriminate a first condition where a single high voltage pulse is generated when an electrical load connected to the power supply line is cut off and a second condition where a high voltage pulse is repeatedly and frequently generated when a failure occurs in the power supply line. Only when the second condition is discriminated, power generation suppression control of the alternator is conducted.

Implementation of a novel control concept for reliable operation of a VIENNA rectifier under heavily unbalanced mains voltage conditions

Abstract: The practical realization of a novel concept for output voltage control and mains voltage proportional guidance of the input currents of a three-phase/switch/level PWM (VIENNA) rectifier system being connected to a heavily unbalanced mains is presented. The control is investigated experimentally for a wide input voltage range 6.5 kW prototype of the VIENNA rectifier.

Power supply device, power supply method, portable electronic apparatus, and electronic timepiece

Abstract: In a rectifier circuit that rectifies an alternating current voltage generated by a generator and supplies the alternating current voltage to a capacitor as a power storage unit, a plurality of level shifters supplies a voltage level-shifted by an offset voltage to respective comparators when the comparators corresponding to transistors perform an on-and-off control, based on voltages across terminals of each of a plurality of transistors forming the rectifier circuit. The offset voltage is set accounting for a response delay time of each comparator. Each transistor is reliably turned off at the time the transistor should be turned off in relation to the voltage across the output terminals of the generator. As a result, a reverse current from the capacitor is thus prevented. A delay in the timing of turning off each transistor is eliminated.

Coupling rectifier systems with harmonic cancelling reactors

Abstract: This paper shows that double-diode rectifiers can generate 12-step voltages by using well-designed line-side reactors, although with relatively large self-inductances. The usage of three-level rectifiers can alleviate this disadvantage. The double three-level rectifier system proposed features the following advantages over conventional transformer-coupled systems: small in size, light in weight, and more economical; control capabilities of output DC voltage in a limited range; low current and voltage ratings required for additional circuits; and highly reliable operation due to 12-step operation capability without additional circuits.

Active rectifier for medium voltage drive systems

Abstract: A uni-directional three-level active rectifier topology is investigated and evaluated for medium voltage applications. The topological differences mandated by different power semiconductors are shown. Switching functions for a harmonic elimination modulation scheme are derived and discussed. The performance of the uni-directional active front-end is investigated and compared to that of a passive rectifier for a 1.8 MVA, 4.16 kV medium voltage converter system.

Infrared inductive light switch using triac trigger-control and early-charging-peak current limiter with adjustable power consumption

Abstract: An electronic switch can replace a standard mechanical light switch for 110-240 volt alternating-current (A.C.) devices. A triac switches the A.C. current to an A.C. device such as a light. A rectifier bridge generates a direct-current (D.C.) voltage that is applied to a special current limiter. The special current limiter generates a large current peak at low voltages, but limits current at high voltages. The large current peak from the special current limiter charges a capacitor when voltage is low at the beginning of each A.C. half-cycle, before the triac turns on. The capacitor has enough charge to supply D.C. current to an Infrared detector and trigger control logic for the rest of the A.C. half-cycle. When the detector detects a person nearby, it signals the trigger control logic. The D.C. voltage from the rectifier bridge is filtered to generate a sync pulse to the trigger control logic when adds a phase delay to the sync pulse which triggers the triac.