Showing papers on "Precision rectifier published in 2003"

Self-tuning digitally controlled low-harmonic rectifier having fast dynamic response

Abstract: This paper describes a completely digitally controlled high-performance low-harmonic rectifier. It is shown that the dynamics of the outer voltage loop can be significantly improved using a self-tuning digital comb filter. Low input current harmonics and fast voltage transient responses are experimentally verified on a 200 W universal-input boost rectifier operating at the switching frequency of 200 kHz.

A low-power wide dynamic range envelope detector

Abstract: We report a 75-dB 2.8-/spl mu/W 100-Hz-10-kHz envelope detector in a 1.5-/spl mu/m 2.8-V CMOS technology. The envelope detector performs input dc insensitive voltage-to-current converting rectification followed by novel nanopower current-mode peak detection. The use of a subthreshold wide linear range transconductor allows greater than 1.7-V/sub pp/ input voltage swings. We show theoretically that the optimal performance of this circuit is technology independent for the given topology and may be improved only by spending more power due to thermal noise rectification limits. A novel circuit topology is used to perform 140-nW peak detection with controllable attack and release time constants. We demonstrate good agreement of experimentally measured results with theory. The envelope detector is useful in low-power bionic implants for the deaf, hearing aids, and speech-recognition front-ends.

12-pulse rectifier for more electric aircraft applications

Abstract: A high power density 10 kW three-phase 12-pulse rectifier is analyzed for applications in future more electric aircrafts. The experimental results, which are in good accordance with the theory, show high efficiency and low input current harmonics for a wide operating range. Furthermore, two novel rectifier topologies, which are formed by combining the passive 12-pulse rectifier with a boost stage on the DC side are proposed. This allows to guarantee a constant output voltage and/or to overcome the problem of the dependency of output voltage on the mains voltage amplitude and output power level.

Circuit for boosting DC voltage

Abstract: A bias circuit that includes a rectifier having an input, an output and a DC control voltage input, wherein the rectifier is configured to produce the rectifier output, while providing a substantially high input impedance at the rectifier input, a rectified voltage from an alternating input signal applied at the rectifier input; and a bias extractor having an extractor input, a control voltage input and an extractor output, coupled to the rectifier output, and being configured to produce at the extractor output a DC voltage that is greater in magnitude than the DC control voltage input.

Analog wavelet transform employing dynamic translinear circuits for cardiac signal characterization

Abstract: An analog QRS complex detection circuit, for pacemaker applications, based on the Wavelet Transform (WT) is presented. The system detects the wavelet modulus maxima of the QRS complex. It consists of a wavelet transform filter, an absolute value circuit, a peak detector and a comparator. In order to achieve the low-power requirement in pacemakers, we propose a new method for implementing the WT in an analog way by means of the Dynamic Translinear (DTL) circuit technique. Simulations indicate a good performance of the WT and the QRS complex detection. The resulting circuit operates from a 2-V supply voltage, dissipates at most 55 nW per scale and can be fully integrated.

High performance CMOS current-mode precision full-wave rectifier (PFWR)

Abstract: This paper presents a high performance CMOS current-mode precision full-wave rectifier. The circuit operates under 3V supply voltage and is designed based on an improved Wilson current mirror. All MOS transistors are biased at low current resulting in small power dissipation. Negative feedback has been employed to reduce the input impedance of the circuit (236/spl Omega/). HSPICE is used to perform the simulation and the result shows the frequency of operation as high as 100 MHz with a standard 0.5 /spl mu/m CMOS technology. The mismatch obtained from the input and rectifier's output is 0.21% for an input current of /spl plusmn/150/spl mu/A. The DC transfer characteristic shows good linearity, very sharp corner at zero crossing point and good symmetry during positive and negative input cycle while power dissipation is 5.8/spl mu/W.

Auxiliary active clamp circuit, a method of clamping a voltage of a rectifier switch and a power converter employing the circuit or method

Abstract: The present invention is directed to an auxiliary active clamp circuit and a method of clamping a voltage of a rectifier switch associated with a power converter. The power converter includes a main active clamp circuit associated with a main power switch coupled to a primary winding of a transformer and a rectifier switch coupled to a secondary winding of the transformer. The main power switch conducts during a main conduction period of the power converter and the rectifier switch conducts during an auxiliary conduction period of the power converter. In one embodiment, the auxiliary active clamp circuit includes an auxiliary clamp capacitor, coupled across the rectifier switch, that stores a clamping voltage substantially equal to an off-state voltage of the rectifier switch. The auxiliary active clamp circuit also includes an auxiliary clamp switch, coupled in series with the auxiliary clamp capacitor, that receives a drive signal from a secondary winding and conducts during the main conduction period thereby clamping a voltage across the rectifier switch at about the clamping voltage.

Adaptive speech filter

Abstract: An adaptive speech filter ( 10 ) for conditioning speech signals to increase signal to noise ratio in a relatively noisy environment. The adaptive speech filter ( 10 ) has a preamp circuit ( 12 ), a high pass adaptive filter circuit ( 14 ), an output buffer circuit ( 16 ), a peak detector amplifier/filter circuit ( 18 ), a peak detector circuit ( 20 ) and a voltage regulator circuit ( 22 ), embodied in an application specific integrated circuit ( 24 ). The adaptive speech filter ( 10 ) is intended for input to telephones, radios, and the like.

Front-end ASIC for a GEM based time projection chamber

Abstract: A time projection chamber for experiments with the laser electron gamma source is being developed. It is composed of a can and a single-ended, dual-stage gas electron multiplier, with associated anode plane pixellated into about 8000 pads. The front-end electronics must provide energy, timing, and address information from those pads involved in measuring each track. For center of gravity determination this information must be sampled from the above-threshold pad and from the two adjacent ones. An efficient scheme for readout of the /spl ap/8000 front-end channels between each measurement cycle is also required. A 32-channel front-end application-specific integrated circuit has been developed to serve this detector. Fabricated in 0.25 /spl mu/m CMOS technology, it dissipates 41 mW. Each channel implements a low noise charge preamplifier with continuous reset of new concept, shaping amplifier with bandgap referenced baseline stabilizer, single threshold discriminator, dual-phase peak detector, timing detector, and logic for neighbor enabling. The readout process is based on token passing and flag.

Contactless IC card

Abstract: A contactless IC card having an antenna, a transmit/receive circuit for recovering data (clock) and electric power from a carrier signal received by the antenna, a logic circuit operated with the electric power supplied thereto from the transmit/receive circuit, and a memory. The transmit/receive circuit has a rectifier circuit for outputting data (clock) and rectifier circuits for electric power in such a manner that the carrier signal is inputted to each of the rectifier circuit for outputting data (clock) and the rectifier circuit for electric power. With this configuration, high frequency matching can be optimized separately for the rectifier circuit for outputting data (clock) and the rectifier circuit for electric power. It is also possible to separately optimize adjustments to a voltage of recovered data (clock) and a recovered supply voltage.

A predictive switching modulator for current mode control of high power factor boost rectifier

Abstract: In this paper, a new variation of current mode control for high power factor operation of boost rectifier is presented. The general features are no input voltage sensing, no use of multiplier, and no inner loop current regulator. It therefore follows the same control structure as that of the linear peak current mode control and the nonlinear carrier control. However, it implements a different switching law for the modulator that extends the range of continuous conduction mode of operation. The switching principle of the modulator is predictive, as the actual current equals the reference current at the end of each switching period. The no. of reset integrators required in this modulator for generation of the carrier waveform is two. The steady-state stability analysis of the boost rectifier with the proposed predictive switching modulator (PSM) is presented in this paper. A low-frequency small-signal model of the boost rectifier switched by the PSM is developed for evaluation of the control transfer function. Experimental results on a 400-W boost rectifier prototype are presented.

Direct power control for three-phase PWM rectifier with active filtering function

Abstract: A novel virtual flux based direct power control space vector modulated (DPC-SVM) for 3-phase PWM rectifier with compensation of higher harmonics function is presented. The active and reactive power is used as a control variables for the PWM rectifier and active filtering operation. As a result several coordinate transformations are eliminated. Simulated and experimental steady state and dynamic performance for PWM rectifier and active filtering operation are presented. Among the main advantages of DPC-SVM are: simple algorithm, good dynamic and operation at constant switching frequency. Additionally a line voltage sensors were replaced by the virtual flux estimator which also help to achieve sinusoidal line current in case of distorted line voltage.

Three-phase active harmonic rectifier (AHR) to improve utility input current THD in telecommunication power distribution system

Abstract: Modern telecommunication power supply systems have several parallel-connected switch-mode rectifiers to provide -48 V DC. A typical switch-mode rectifier configuration includes a three-phase diode rectifier followed by a DC-DC converter. Such a system draws significant harmonic currents for the utility, resulting in poor input power factor and high total harmonic distortion. In this paper, a three-phase active harmonic rectifier (AHR) scheme is proposed. In the AHR scheme, a diode rectifier module is replaced by a six-insulated-gate-bipolar-transistor pulsewidth-modulation rectifier to supply load harmonics as well as its own active power. Each DC-DC converter module is connected to a shared 48-V DC link. The AHR module together with parallel-connected switch-mode rectifiers is controlled to achieve clean input power characteristics. The VA ratings of the AHR scheme is compared with an active power filter approach. The control design is based on the synchronous reference frame approach. Analysis, simulation, and experimental results show that the AHR offers several advantages such as lower VA rating, better current control response, efficient use of the AHR DC link, small size, and stable DC-link voltage control.

Modeling and control strategy for a single-phase PWM rectifier using a single-phase instantaneous active/reactive power theory

Abstract: This paper deals with a fast dc voltage control strategy for a single-phase PWM rectifier. The PWM rectifier must control the active and reactive powers for regulating the dc voltage. Then, in this paper, a single-phase instantaneous active/reactive power theory (the ps-qs theory) is applied to a control strategy of a single-phase PWM rectifier. In addition, the stability of a single-phase PWM rectifier is analyzed, and a novel circuit topology and control strategy using a dc active filter is proposed. Some significant characteristics on our proposal are verified by using a 100 V/1.8 kVA experimental system.

Simple and Advanced Methods for Calculating Six-Pulse Diode Rectifier Line-Side Harmonics

Abstract: This paper proposes different methods for estimation of the harmonic currents of the six-pulse diode rectifier, which is a very commonly used topology in industry. Both simple and advanced models are compared and the models are put into a context of practical use for calculating the harmonic distortion in a typical industrial application. Finally, the different models are compared to measurements of a real application and convincing results are achieved concluding that the proposed methods can be used.

Capacitively coupled power supply

Abstract: A power supply includes a supply inductor and a first capacitor coupled to form a resonant circuit to generate a resonant waveform in a resonant operation, during a first portion of an operation cycle of the power supply. A charge storage element develops an output voltage to energize a load. A rectifier is coupled to the charge storage element and to the resonant circuit and is responsive to the resonant waveform for applying the output voltage back to the resonant circuit to interrupt the resonant operation, at an end time of the operation cycle first portion, when the resonant waveform produces a first change of state in the rectifier. A first sensor senses when the first change of state in the rectifier occurs. A source of a supply current is coupled to the rectifier and rectified in the rectifier to produce a rectified current that is coupled to the charge storage element to replenish a charge therein, during a second portion of the operation cycle. A switching transistor is responsive to an output signal of the first sensor for enabling the supply current to be coupled to the rectifier, during the operation cycle second portion, and for disabling the supply current from being coupled to the rectifier, during the operation cycle first portion.

Circuit and method for controlling a synchronous rectifier in a power converter

Abstract: A control circuit and corresponding method, particularly for power converters in a system having paralleled power converters, for rapidly and efficiently controlling a free-wheeling synchronous rectifier, so as to prevent any large negative current flow that might cause damage to components of the converter during a fault condition where the PWM signal turns off or has missing cycles. Preferably, clock signal and the gate drive output of a PWM controller are compared in order to recognize a failure condition and to rapidly provide control of the synchronous rectifier so as to prevent the large negative current flow. Control of the free-wheeling synchronous rectifier is provided in a way that is dependent on the gate drive output of the PWM controller and independent of timing, current sense signals, voltage sense signals, the current share system, and the operation of the forward synchronous rectifier of the power converter.

Active rectifier module for three-phase generators of vehicles

Abstract: The invention relates to a rectifier for rectifying alternating current into direct current, in which a three-phase generator comprises a three-phase stator winding (9). The phases (11, 12, 13) of the stator winding (9) are controlled by means of switching elements (15.1, 15.2; 16.1, 16.2; 17.1, 17.2) of a power circuit (8). The latter (8) is controlled by a control part (2), which comprises a regulator module (3, 55). The rectifier (1) comprises a control part (2) (control module), equipped with control connections (30) and a power circuit (8) (power module), which is controlled by said part, optionally provided with a cooling device (23, 24) and in which all the power conducting components (15.1, 15.2, 16.1, 16.2; 17.1, 17.2; 13) are configured as power MOS components (28) and integrated in a stacked construction (20).

Digital control of an integrated series active filter and diode rectifier with voltage regulation

Abstract: The integration of a series active filter with a 12-pulse diode rectifier can provide a cost-effective and efficient means of supply current harmonic-free AC/DC conversion. Controlling the series active filter as a frequency-selective impedance requires low delays and is not well suited for digital control. This paper suggests a current-mode control strategy to allow full digital control of the active filter. The suggested current-mode control method for supply current balancing and voltage regulation is verified experimentally.

Multiple output converter with improved cross regulation

Abstract: A cost effective circuit improves the cross regulation of multiple outputs converter, especially for that output chokes are coupled and a synchronous rectifier is applied to one of the outputs. A DC/DC converter includes a transformer having a primary winding and two secondary windings. The first secondary winding is coupled to a synchronous rectifier and a first output choke. The second secondary winding is coupled to a diode rectifier and a second output choke. The first output choke and the second output choke are coupled. A low power MOSFET switch is added to the diode rectifier for avoiding the diode rectifier operating in DCM when light loaded.

Arc-machining power supply with switching loss reducing element

Abstract: A power supply for performing arc-machining operation includes a primary rectifier connected to the commercial AC power source and an inverter coupled to the rectifier. A switching device is provided between the rectifier and the inverter. By controlling the power supplied from the rectifier to the inverter, the switching device prevents a large switching loss from occurring in the inverter.

Bi-directional single-phase half-bridge rectifier for power quality compensation

Abstract: A single-phase half-bridge rectifier with a capacitor clamped scheme is proposed. Four power switches and one flying capacitor are employed in the proposed rectifier. Bipolar and unipolar PWM control schemes are used to perform power factor correction and achieve low total harmonic distortion of line current. A neutral point voltage balance compensator, hysteresis current controller and DC link voltage regulator are used to balance neutral point voltage, to track line current command, and to maintain the constant DC bus voltage. The proposed control scheme and the circuit configuration can also perform a shunt active power filter operation to eliminate the harmonic currents and compensate the reactive power generated from the nonlinear load. Analytical and experimental results are presented to illustrate the validity and effectiveness of the proposed control scheme.

Soft-start with back bias conditions for PWM buck converter with synchronous rectifier

Abstract: A circuit that efficiently prevents the turning on of the synchronous rectifier in a buck converter during a predetermined condition, so as to prevent current reversing through the synchronous rectifier during that time. In one embodiment, the circuit provides control of the synchronous rectifier during the soft-start time for a non-isolated DC-DC buck converter, thereby preventing current reversing (sinking), referred to as the back bias condition, during its soft start process. In another embodiment, a circuit uses a signal indicative of a soft-start condition for a converter to prevent the turning on of the synchronous rectifier during the soft-start time. A corresponding system solves the aforementioned synchronous rectifier back bias problem for converters used in a paralleled converter configuration.

A smart synchronous rectifier for 12 V automobile alternators

Abstract: A new gate control unit for power MOSFETs is presented in this paper, which is especially suited for synchronous rectifiers in 12 V automobile vehicle-nets to replace inefficient silicon diodes. Unlike known control units for such synchronous rectifiers based on comparator circuits or external timing control, the proposed circuitry is inexpensive and insensitive, as it consists of only one operational amplifier and some passive components per MOSFET. Measurements taken on a prototype synchronous rectifier connected to a standard passenger car's alternator prove a major increase of the rectification efficiency as well as a higher output current of the alternator compared to a standard diode rectifier. This synchronous rectifier operates at load currents up to 120 A and up to a maximum alternator speed of 15000 rpm. The entire gate drive circuit is described, providing information about the desired properties of its components. The switching processes of the presented circuit as well as the parameters that determine its operational performance are explained in detail.

Power circuit and method for controlling drive and control voltages of an image formation apparatus

Abstract: Synchronous rectifier circuits are provided for each secondary windings of a transformer. Field-effect transistors of which ON voltage is lower than the forward voltage of a diode are provided in each of the synchronous rectifier circuits. In an energy saving mode, the field-effect transistors in the synchronous rectifier circuit that outputs a diving voltage are turned OFF. A comparator circuit outputs a signal corresponding to a difference between a control voltage output from one of the synchronous rectifier circuits and a reference voltage. Based on this signal, a pulse-width modulation control circuit ON/OFF controls a field-effect transistor provided corresponding to a primary winding of a transformer in such a manner that the control voltage the reference control voltage attain predetermined levels.

Synchronous rectifier gate drive circuits for zero voltage switching power converters

Abstract: Synchronous rectifier gate drive mechanisms are revealed which are universally applicable to zero voltage switching power converters which rely on an auxiliary inductor to drive the critical turn on transition of the main switch of the power converter. One of the gate drive mechanisms revealed can also be used to improve the ZVS load range of the converter and to increase the power capability of the converter. Voltage limiting circuits that clamp the gate voltage of a synchronous rectifier during the turn off transition of the synchronous rectifier, preventing inadvertent turn on of the synchronous rectifier, are revealed.

Power factor correction circuit with high-voltage semiconductor component

Abstract: A switching power supply including a power factor correction circuit comprises a rectifier, an inductor coupled in series with the rectifier, a semiconductor switch formed by a compensation device coupled in parallel with the rectifier and the inductor. The output circuit comprises a diode coupled in series with a capacitor both coupled in parallel with the semiconductor switch. An input current sensor, and a control unit for controlling the compensation device are provided.

A CMOS current-mode squarer/rectifier circuit

Abstract: In this paper, a new current squarer and precision full-wave rectifier based on a CMOS class AB amplifier that modified to receive a differential input current has been presented. The proposed circuits are simulated with HSPICE level 49. From a /spl plusmn/1.5 V supply voltage, the power consumption of the rectifier and the squarer at the quiescent point are about 210 nW and 120 /spl mu/W, respectively. The total harmonics distortion of the-squarer is less than 1%, with a input signal of 24 /spl mu/A.