Showing papers on "Precision rectifier published in 2005"

Comparative evaluation of three-phase high-power-factor AC-DC converter concepts for application in future More Electric Aircraft

Abstract: A passive 12-pulse rectifier system, a two-level, and a three-level active three-phase pulsewidth-modulation (PWM) rectifier system are analyzed for supplying the dc-voltage link of a 5-kW variable-speed hydraulic pump drive of an electro-hydrostatic actuator to be employed in future More Electric Aircraft. Weight, volume, and efficiency of the concepts are compared for an input phase voltage range of 98-132 V and an input frequency range of 400-800 Hz. The 12-pulse system shows advantages concerning volume, efficiency, and complexity but is characterized by a high system weight. Accordingly, the three-level PWM rectifier is identified as the most advantageous solution. Finally, a novel extension of the 12-pulse rectifier system by turn-off power semiconductors is proposed which allows a control of the output voltage and, therefore, eliminates the dependency on the mains and load condition which constitutes a main drawback of the passive concept.

A model for /spl mu/-power rectifier analysis and design

Abstract: This paper proposes a linear two-port model for an N-stage modified-Greinacher full-wave rectifier. It predicts the overall conversion efficiency at low power levels where the diodes are operating near their threshold voltage. The output electrical behavior of the rectifier is calculated as a function of the received power and the antenna parameters. Moreover, the two-port parameter values are computed for particular input voltages and output currents for the complete N-stage rectifier circuit using only the measured I-V and C-V characteristics of a single diode. To validate the model a three-stage modified-Greinacher full-wave rectifier was realized in an silicon-on-sapphire (SOS) CMOS 0.5-/spl mu/m technology. The measurements are in excellent agreement with the values calculated using the presented model.

Integrated torsional mode damping system and method

Abstract: An integrated torsional mode damping method for a current source converter, including a rectifier, an inverter, and a DC link inductor coupled between the rectifier and the inverter, includes sensing a signal representative of torque on a shaft coupled to the inverter or rectifier; using the sensed signal for detecting a presence of a torsional vibration on the shaft; and damping the torsional vibration by modulating active power through the respective inverter or rectifier.

A novel zero-Voltage-switching PWM boost rectifier with high power factor and low conduction losses

Abstract: This paper proposes a new single-phase high-power-factor rectifier, which features regulation by conventional pulsewidth modulation (PWM), soft commutation, and instantaneous average line current control. A new zero-voltage-switching PWM (ZVS-PWM) auxiliary circuit is configured in the presented ZVS-PWM rectifier to perform ZVS in the main switches and the passive switches, and zero-current switching in the auxiliary switch. Furthermore, soft commutation of the main switch is achieved without additional current stress by the presented ZVS-PWM auxiliary circuit. A significant reduction in the conduction losses is achieved, since the circulating current for the soft switching flows only through the auxiliary circuit and a minimum number of switching devices are involved in the circulating current path, and the proposed rectifier uses a single converter instead of the conventional configuration composed of a four-diode front-end rectifier followed by a boost converter. Nine transition states for describing the behavior of the ZVS-PWM rectifier in one switching period are described. A prototype rated at 1 kW, operating 80 kHz, with an input ac voltage of 220 V/sub rms/ and an output voltage of 400 V/sub dc/ has been implemented in the laboratory. An efficiency of 96.7% and power factor over 0.99 has been measured. Analysis, design, and the control circuitry are also presented in this paper.

A constant output current three-phase diode bridge rectifier employing a novel "Electronic Smoothing Inductor"

Abstract: This paper presents an improvement of the well-known conventional three-phase diode bridge rectifier with dc output capacitor. The proposed circuit increases the power factor (PF) at the ac input and reduces the ripple current stress on the smoothing capacitor. The basic concept is the arrangement of an active voltage source between the output of the diode bridge and the smoothing capacitor which is controlled in a way that it emulates an ideal smoothing inductor. With this the input currents of the diode bridge which usually show high peak amplitudes are converted into a 120/spl deg/ rectangular shape which ideally results in a total PF of 0.955. The active voltage source mentioned before is realized by a low-voltage switch-mode converter stage of small power rating as compared to the output power of the rectifier. Starting with a brief discussion of basic three-phase rectifier techniques and of the drawbacks of three-phase diode bridge rectifiers with capacitive smoothing, the concept of the proposed active smoothing is described and the stationary operation is analyzed. Furthermore, control concepts as well as design considerations and analyses of the dynamic systems behavior are given. Finally, measurements taken from a laboratory model are presented.

A bidirectional and isolated three-phase rectifier with soft-switching operation

Abstract: A bidirectional-power-flow three-phase rectifier with high-frequency isolation and all-digital control, based on the matrix converter topology, is analyzed in this paper. The selected topology consists of a bidirectional three-phase-to-single-phase reduced matrix converter with power-factor correction and a bidirectional active rectifier. The inclusion of the isolation transformer at the switching frequency permits the reduction of volume and weight. By synchronizing the commutation of both converters and adding a saturable inductor and a blocking capacitor it is possible to achieve soft commutation for most of the semiconductor elements. An all-digital control based on a digital-signal-processor and a field-programmable gate array was used to implement space-vector modulation and output current regulation. This power converter is intended to feed the low-energy correction magnet of a particle accelerator. Experimental results of a 1.5-kW 20-kHz prototype are presented to illustrate the performance of the proposed topology.

Regenerative medium-voltage AC drive based on a multicell arrangement with reduced energy storage requirements

Abstract: Multicell power circuit topologies have proved to be an effective alternative to medium-voltage ac drives. The main advantage is the improved power quality at both the ac system and the motor sides. However, several drawbacks are present in these configurations, such as a lack of sustained regenerative operating mode, uncontrolled input reactive power, and a large second current harmonic that is injected by the load into the dc link of each cell, which leads to a bulky electrolytic capacitor. This paper proposes to replace the input diode-based front-end rectifier with an active front-end rectifier in all cells of the topology and a novel control strategy in order to overcome the aforementioned drawbacks. In fact, the active front-end rectifier allows the topology to regenerate and the control strategy handles the reactive input power and reduces the large second current harmonic from the dc-link capacitor, thus reducing its size. These features are achieved without any penalties in the quality of both the ac input current and the motor voltage waveforms. Experimental results confirm the theoretical considerations.

Unity power factor control for three phase three level rectifiers without current sensors

Abstract: Three level rectifiers with reduced number of switches (such as the Vienna rectifier) have been receiving wide interest in the past years to improve the input power quality of rectifier systems. In this paper, a new carrier-based pulse width modulation (PWM) control algorithm is proposed for such converters to eliminate the low frequency harmonics in the line current while achieving unity power factor at the rectifier input terminals. The operating constraints of the Vienna rectifier with the carrier-based modulation strategy are examined carefully and the proposed control algorithm ensures that appropriate voltage/current directional constraints are met. A promising cost reduction opportunity can be seen with elimination of input current sensing to operate the Vienna rectifier. The control algorithm is verified via Saber simulation and experimental results.

A 950 MHz rectifier circuit for sensor networks with 10 m-distance

Abstract: A high-sensitivity rectifier is fabricated in a 0.3 /spl mu/m CMOS technology. The circuit can rectify an RF signal less than the NMOS threshold voltage by using a bias voltage between the gate and the drain terminals of a transistor. The IC achieves a 950 MHz signal rectification over -14 dBm corresponding to 10 m-distance communication and recharges a 1.2 V secondary battery.

A Full-Wave Rectifier using a Current Conveyor and Current Mirrors with Improved Efficiency

Abstract: A full-wave rectifier using a current conveyor and current mirrors proposed by Monpapassorn e/ al. (2001) is improved. The improved rectifier uses two voltage sources in place of two transistordiodes and three constant current sources of the original rectifier. The improvement yields better performance in view of device number, power consumption and operation frequency. Simulation results that agree with theory are included.

A 70GHz cascaded multi-stage distributed amplifier in 90nm CMOS technology

Abstract: An offset-compensation method uses a peak detector and multiple tap feedback to achieve 1000/spl times/ improvement in settling time compared to prior art. Measurement results for a 3.125 Gbit/s limit amplifier with 42dB gain implemented in a 0.18 /spl mu/m CMOS process are presented.

A novel ZCS-PWM power-factor preregulator with reduced conduction losses

Abstract: This paper proposes a new single-phase high-power-factor rectifier, which features regulation by conventional pulsewidth modulation (PWM), soft commutation, and instantaneous average line current control. A new zero-current-switching PWM (ZCS-PWM) auxiliary circuit is configured in the presented ZCS-PWM rectifier to perform ZCS in the active switches and zero-voltage switching in the passive switches. Furthermore, soft commutation of the main switch is achieved without additional current stress by the presented ZCS-PWM auxiliary circuit. A significant reduction in the conduction losses is achieved, since the circulating current for the soft switching flows only through the auxiliary circuit and a minimum number of switching devices are involved in the circulating current path and the proposed rectifier uses a single converter instead of the conventional configuration composed of a four-diode front-end rectifier followed by a boost converter. Nine transition states for describing the behavior of the ZCS-PWM rectifier in one switching period are described. The PWM switch model is used to predict the system performance. A prototype rated at 1 kW, operating 50 kHz, with an input ac voltage of 220 V/sub rms/ and an output voltage 400 V/sub dc/ has been implemented in laboratory. An efficiency of 97.3% and power factor over 0.99 has been measured. Analysis, design, and the control circuitry are also presented in this paper.

A clean four-quadrant sinusoidal power rectifier using multistage converters for subway applications

Abstract: A special 27-level four-quadrant rectifier for subway applications is analyzed. The arrangement uses only three H-bridges per phase, common dc bus, and independent input transformers for each H-bridge. The transformers allow galvanic isolation and power escalation to obtain high-quality voltage waveforms, with total harmonic distortion of less than 1%. Some advantages of this 27-level rectifier are: 1) only one of the three H-bridges, called the main converter, manages more than 80% of the total active power in each phase and 2) it switches at fundamental frequency, reducing the switching losses at a minimum value. The rectifier analyzed in this paper is a current-controlled voltage-source type, with a conventional feedback control loop. Some simulations in a rectifier substation, including power reversal at full load are displayed (750 Vdc, 1200 A). The rectifier shows the ability to produce clean ac and dc waveforms without any ripple, and fast reversal of power. Some experimental results with a small prototype, showing voltage and current waveforms, are finally displayed.

A three-phase unity-power-factor diode rectifier with active input current shaping

Abstract: This paper proposes a new three-phase diode rectifier that actively shapes the input current by means of two direct current dc-dc converters operating at continuous conduction mode. The proposed approach draws sinusoidal input current at unity power factor and has output voltage regulation capability. The size and weight of the magnetic devices is reduced since a low-kilovolt-ampere three-phase autotransformer is incorporated and dc outputs of two bridges are directly connected without using low-frequency interphase transformers (IPTs).

Three-phase single-stage four-switch PFC buck-boost-type rectifier

Abstract: This paper proposes a new three-phase single-stage power-factor corrector buck-boost-type rectifier topology. The typical topology uses a bridge configuration with six switches. This new topology only requires four switches, improving the rectifier efficiency as only one reverse-blocking power semiconductor conducts at any time. A vector-based sliding-mode control method for the three-phase input currents is also proposed. This fast and robust technique uses sliding mode to generate /spl alpha//spl beta/ space-vector modulation, which forces the input line currents to track a suitable sinusoidal reference. A near-unity power-factor operation of the rectifier is obtained using a sinusoidal reference in phase with the input source voltages. A proportional-integral controller is adopted to regulate the output voltage of the converter. This external voltage controller modulates the amplitude of the current references. The characteristics of the new rectifier are verified with experimental results.

Bi-directional ESD protection circuit

Abstract: An electrostatic discharge (ESD) device for protecting an input/output terminal of a circuit, the device comprising a first transistor with an integrated silicon-controlled rectifier (SCR) coupled between the input/output (I/O) terminal of the circuit and a node and a second transistor with an integrated silicon-controlled rectifier coupled between the node and a negative terminal of a supply voltage, wherein the silicon-controlled rectifier of the first transistor triggers in response to a negative ESD voltage and the silicon-controlled rectifier of the second transistor triggers in response to a positive ESD voltage.

Semiconductor circuit for driving light emitting diode, and light emitting diode driving apparatus

Abstract: A light emitting diode drives a semiconductor circuit in order to drive a light emitting diode that emits light by applying the output voltage of the rectifier circuit. The light emitting diode includes a switching element connected between the light emitting diode and the ground potential. An input voltage detection circuit detects the output voltage of the rectifier circuit to output a light emitting signal or a extinction signal. A current detection circuit detects the current flowing into the switching element. A control circuit intermittently controls on/off of the switching element at a predetermined oscillating frequency based on the output signal of the current detection circuit while the input voltage detection circuit is outputting the light emitting signal.

GaN semiconductor based voltage conversion device

Abstract: A converter is provided having an AC input and a DC output. The converter includes a rectifier that receives the AC input and that provides a rectifier output, a series connected current to magnetic field energy storage device and current interrupter connected across the rectifier output and a series connected gallium nitride diode and output charge storage device connected between a midpoint of the series connected magnetic field energy storage device and current interrupter and a terminal of the rectifier output and wherein the converter is characterized in not needing a transient voltage suppression circuit.

A new three-phase harmonic-free rectification scheme based on zero-sequence current injection

Abstract: This paper proposes a new three-phase harmonic-free rectification scheme based on a zero-sequence injection technique. The proposed scheme incorporates two half-bridge inverters and two single-phase transformers to actively and individually shape the positive and negative dc rail currents of the rectifier. The shaped zero-sequence harmonic currents are then circulated through the ac side of the rectifier via a zigzag transformer, resulting in pure sinusoidal input currents in the three-phase diode rectifier. A design example along with component ratings calculation are detailed. Experimental results on a 1.5-kVA prototype are provided to validate the proposed technique.

Three Phase Z-Source Rectifier

Abstract: This paper makes the research on an impedance-source rectifier (abbreviated as Z-source rectifier), describes the operating principle, operating modes, and its concept and superiority. Analysis and simulation results show that the three-phase Z-source rectifier can buck-boost voltage by using the shoot-through state, which is harmful for the conventional VSR. It needs small dc-link inductor L and capacitor C, and makes the input unity power factor become possible without any additional circuits, minimize component count, and increase efficiency

A novel unity power factor input stage for AC drive application

Abstract: In this paper, a new method of improving the input current total harmonic distortion (THD) as well as power factor of a three-phase suppressed-link rectifier-inverter is presented. This proposed method makes use of a novel controlled diode rectifier. The technique involves the use of bidirectional switches across the front-end rectifier, and a dSPACE based intelligent control algorithm. The operation of the converter is fully analyzed and design example provided. The main feature of the topology is low cost, small size, high efficiency and simplicity, and is excellent for retrofitting front-end rectifier of existing ac drives, UPS etc.

A Novel Unidirectional Hybrid Three-Phase Rectifier System Employing Boost Topology

Abstract: This paper presents a new hybrid rectifier composed by the parallel association of a single-switch three-phase boost rectifier with a PWM three-phase unidirectional rectifier. According to this proposal, each rectifier processes about a half of the output rated power. Thus, it allows to improve the robustness and to provide a high efficiency to the system. The hybrid rectifier is capable of providing output voltage regulation and power factor correction. An overview of some high power rectifier topologies and the mathematical analysis, the control scheme and the simulation results of the proposed hybrid rectifier are also presented in this paper

Efficiency comparison of voltage source and current source drive system for medium voltage applications

Abstract: This paper calculates and compares the efficiency and loss distribution in three most popular state-of-the-art types of medium voltage drive systems; current source drive with active front-end rectifier, current source drive with 18-pulse thyristor rectifier, and three-level voltage source drive with 12-pulse/24-pulse diode rectifier. Based on the proposed simple and accurate method of calculating switching losses, snubber and filter losses, three-level voltage source drive system has been found to produce the highest efficiency of 98.77% under the rated load of 1.6 MW

New precision rectifier circuits with high accuracy and wide bandwidth

Abstract: Two new circuits for precise full-wave rectification are presented. The first is based on a current feedback amplifier with a new current-mode absolute-value circuit in its feedback loop. The second utilizes an operational conveyor working in conjunction with a current-mode absolute-value circuit in a new configuration. Both circuits have high accuracy and wide bandwidth, giving undistorted rectified waveforms up to 500 kHz in the first case and 1 MHz in the other. Additionally, both systems have high sensitivity, being able to full-wave rectify signals with amplitudes as small as 5 mV peak at 100 kHz. Finally, the new systems have excellent temperature stability, low offset output voltage and are suitable for IC fabrication.

New Multi-Phase Diode Rectifier Average Models for AC and DC Power System Studies

Abstract: More power semiconductors are applying to the aircraft power system to make the system smaller, lighter and more reliable. Average models provide a good solution to system simulation and can also serve as the basis to derive the small signal model for system-level study using linear control theory. A new average modeling approach for three-phase and nine-phase diode rectifiers with improved ac and dc dynamics is proposed in this dissertation. The key assumption is to model the load current using its first-order Taylor Series expansion throughout the entire averaging time span. A thorough comparison in the time domain is given of this model and two additional average models that were developed based on different load current assumptions, using the detailed switching models as the benchmark. The proposed average model is further verified by experimental results. In the frequency domain, the output impedance of a nine-phase diode rectifier is derived, and the sampling effect in the average model is investigated by Fourier analysis.

Digital implementation of a unity-power-factor constant-frequency DCM boost converter

Abstract: A DSP implementation of digital control for constant-frequency, unity-power-factor, and discontinuous-conduction-mode boost rectifier is described. By employing variable-duty-cycle control, the power factor of over 0.99 is achieved in the entire universal line-voltage range (90-264 V). In addition, the transient response of the rectifier is optimized by utilizing a nonlinear PI-controller with anti windup that is independently optimized for U.S. line-voltage range (90-132 V) and for European line-voltage range (180-264 V) and by temporarily increasing the bandwidth of the control loop during transients. The performance of the proposed DSP control was verified on a 100-kHz, 400-W unity-power-factor rectifier prototype

Improving efficiency of the active-clamped SEPIC rectifier at high line frequencies

Abstract: The performance of a conventional isolated SEPIC rectifier can be improved with an active voltage clamp. Relatively high efficiency and low total harmonic distortion (THD) can be achieved with an active-clamped SEPIC rectifier in high-line-frequency (360-800 Hz) avionics applications. However, it is observed that a diode conduction problem affects the rectifier efficiency as the line frequency increases. This paper explains the diode conduction problem and presents a solution that is based on a variation of the same topology. An efficiency of 90% has been achieved for a power level of 100 W over the entire line frequency range. Additionally, the solution offers the possibility of high-voltage bulk energy storage

Novel Direct-Power-Control Strategy of Current-Source PWM Rectifier

Abstract: This paper describes a novel control strategy of a current-source PWM rectifier, which is based on relay control of instantaneous active and reactive power, and presents its experimentally examined operation characteristics, followed by a theoretical derivation of the control algorithm The most important feature of this strategy is a direct selection of switching modes of the PWM rectifier to restrict errors between the feedback values and the command values of the active and reactive power Therefore, a theoretical analysis on relationship between the instantaneous power and the switching modes of the PWM rectifier is deeply investigated, which is essential to compose a switching mode table in the controller Feasibility of the proposed strategy is experimentally verified, using a prototype setup As a result, 927-% maximum efficiency and 999-% maximum total power factor are confirmed through the experimental tests

System linking apparatus for generated electric power

Abstract: A system linking apparatus for generated electric power which may be made smaller and more efficient. The system linking apparatus is intended for connecting an electric power system to an output of a power generator through a linking inverter (PWM inverter). The system linking apparatus includes a magnetic energy regenerating circuit, a diode rectifier, and a capacitor. The magnetic energy regenerating circuit has a capacitor for condensing magnetic energy condensed in the power generator. The diode rectifier is connected with the magnetic energy regenerating circuit and operates to dc convert electric power generated by the power generator and output the converted power to the linking inverter. The capacitor is connected with the diode rectifier and operates to keep a dc output to the linking inverter at a predetermined voltage.