Showing papers on "Precision rectifier published in 2004"

Far-field RF power extraction circuits and systems

Abstract: A method and apparatus for performing far-field power extraction are presented. The method includes receiving an electromagnetic radiation signal, rectifying the signal to produce a direct current (D.C.) voltage and providing the D.C. voltage to a circuit. A far-field power extraction circuit includes an antenna for receiving an electromagnetic radiation signal, a rectifier for rectifying the electromagnetic radiation signal. The circuit may further include a charge pump for amplifying the rectified voltage, an impedance matching network for coupling the antenna to the rectifier and a feedback tuning circuit for optimizing performance of the extraction circuit.

Diode receiver for radio frequency transponder

Abstract: A passive radio frequency transponder (RF tag) having a diode rectifier receiver circuit outside the tag power rectification circuit, the tag power rectification circuit supplying power to the electronics of the RF tag. An additional innovative low current circuit protect the signal capacitor from overvoltage produced by the signal diode. An innovative circuit also clips the signal and sharpens it. An innovative low current circuit is used as a comparator to sharpen the signal pulses.

Boost rectifier with half-power rated semiconductor devices

Abstract: A rectifier has two half-controlled bridge rectifiers which are connected in parallel to provide DC power to DC bus lines. Each bridge rectifier receives AC power through inductances such as series inductors or an isolation transformer with a single primary and two secondaries. Each bridge rectifier has a full bridge of diodes, with active switching devices connected in parallel with half of the diodes in the bridge. The switching devices can be controlled to provide unity power factor at the AC input lines, allowing lower rated diodes and switching devices to be used.

A novel single-phase soft-switched rectifier with unity power factor and minimal component count

Abstract: A novel, single-phase soft-switched boost AC-DC rectifier that operates with power-factor correction is proposed in this paper. The rectifier is a modified boost voltage-doubler converter well suited for low-line-input applications. It operates with fewer conduction losses and half the switch voltage stresses found in a standard boost converter. Soft switching in the converter is achieved using a zero-current-switching quasi-resonant technique. In the paper, the converter and its modes of operation are discussed and analyzed. The method of control is explained, and a design procedure is derived and then demonstrated with an example. The feasibility of the converter is shown with experimental results obtained from a prototype.

Comparative evaluation of three-phase high power factor AC-DC converter concepts for application in future more electric aircrafts

Abstract: A passive 12-pulse rectifier system, a two-level, and a three-level active three-phase 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 aircrafts. Weight, volume and efficiency of the concepts are compared for an input phase voltage range of 98 V to 132 V and an input frequency range of 400 Hz to 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 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.

Forward converter with synchronous rectifier and reverse current control

Abstract: A control circuit for use in a power converter having a synchronous rectifier for producing substantially direct current including a sensor for sensing a characteristic of the power converter, detection circuitry capable of using the characteristic to develop a control signal for controlling the power converter, and synchronous rectifier control circuitry connected to the detection circuitry wherein the control circuitry is adapted to modify a duty cycle of the power converter as a function of the control signal thereby to turn off a freewheel switch of the synchronous rectifier before turning off a forward switch of the synchronous rectifier during a reverse current period.

Regenerative drive converter with line-frequency switched rectifier and without DC link components

Abstract: The presented regenerative drive converter consists of a line-side three-phase rectifier and a motor-side three-phase inverter. Antiparallel to the rectifier diodes there are six IGBTs, which conduct the DC link current, if it flows from the inverter to the rectifier. In the DC link there are no components: neither an inductor or an electrolytic capacitor nor a braking resistor or a braking chopper. Between the line and the rectifier there is a filter, comprising a three-phase inductor and three capacitors. As the antiparallel IGBTs are switched with line frequency, their switching pattern is very simple, because it is synchronized with the line voltage. Because of the low additional effort this converter type is very advantageous, when regenerative operation is expected and when low frequency harmonic content of the line current is not critical and does not require a converter with pulsed active front end. The proposed paper describes the basic function of this type of converter. It is shown, that the simple switching pattern for the line-side IGBTs can be generated very easily. The requirements for the line-side filter, its topology and its design are illustrated. A test set-up of this converter with an induction-motor of 7.5 kW is described and experimental results hereof are presented. The DC-link voltage is not ideal, but superimposed by the line-harmonics caused by the rectifier. The resulting influences for the motor can be minimized by means of the PWIV1 strategy of the motor-side inverter. The experimental results show, that the waveforms and the spectrum of the motor voltages and'currents and the waveforms and the spectrum of the line currents confirm the theoretical considerations. Measurements of the efficiency of the rectifier show, that its losses are low because of the absence of switching losses. The experimental results show as well, that additional losses of the motor due to the fluctuating DC link voltage are negligible.

A new single-phase ZCS-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 PWM, soft commutation and instantaneous average line current control. A new zero-current-switching pulse-width modulation (ZCS-PWM) auxiliary circuit is configured in the presented ZCS-PWM rectifier to perform ZCS in the active switches and ZVS 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. Seven 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 60 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 98.3% and power factor over 0.99 has been measured. Analysis, design, and the control circuitry are also presented in this paper.

Single-phase half-bridge rectifier with power factor correction

Abstract: A single-phase half-bridge switching mode rectifier is presented to draw a sinusoidal line current, to achieve power factor correction and to maintain the DC-link voltage constant. Four active switches are used in the proposed rectifier to generate a unipolar pulse width modulation (PWM) voltage waveform on the AC terminal voltage. There is no clamping diode in the proposed rectifier (as compared with the neutral point clamped (NPC) converter) so as to achieve three-level PWM operation. Two control loops are used in the proposed control scheme. In the outer control loop, a proportional integral voltage controller is used to regulate the DC-link voltage. A phase lock loop circuit is adopted to generate a sinusoidal waveform in phase with mains voltage to achieve power factor correction. In the inner control loop, a carrier-based current controller is used to track the line current command. To compensate the neutral point voltage due to the load variation, a neutral point voltage compensator is used in the control scheme. Three voltage levels are generated on the AC terminal of the adopted rectifier. Computer simulations and experimental results are presented to verify the effectiveness of the proposed control algorithm.

DC-link capacitor reduction of a controlled rectifier supplying N inverter-motor drive systems by compensating the load variations

Abstract: This paper deals with the compensations of the load variations in the control of DC-link voltage of the cascade of one rectifier-N inverter motor drive systems. The objective is to reduce the capacitance of the DC-link capacitors without affecting the stability of the DC-voltage control; so, the rectifier controllers should anticipate the load variation of the N inverter-motor drive systems. This is achieved by introducing compensating structures in the rectifier controllers; then, the DC-link voltage becomes almost insensitive to the load variations. This makes possible to design independently the controllers of the controlled rectifier from those of the inverter-motor assemblies. The presented simulation results validate the efficiency of the proposed methods.

Dual mode rectifier, system and method

Abstract: A system for generating an output power to a load is provided. The system comprises a generator configured for generating a variable frequency output power and a dual mode rectifier coupled to the generator and configured for being switched between a passive mode and an active mode. The dual mode rectifier comprises a passive rectifier coupled to output terminals of the generator and configured for operating in the passive mode and an active converter coupled to tappings from windings of the generator and configured for operating in the active mode.

A simplified algorithm for space vector modulation of three-phase voltage source PWM rectifier

Abstract: A simplified algorithm is proposed in this paper for space-vector modulation (SVM) of three-phase voltage source PWM rectifier. The transfer function and control loop design of the rectifier are detail described. For three-phase voltage source PWM rectifier, the space-vector modulation scheme has excellent features such as increased utilized voltage, easy implementation via microprocessor etc. In this paper the duty cycles of space voltage vectors are calculated directly to track the reference voltage vector in each sector of the space vector plane. It avoids the look-up tables of sine and/or arctangent and complex calculations needed in the conventional methods. Based on experimental platform for Power Electronics "PE-PRO / VC33", the experimental results demonstrated that the proposed system also has the advantages including unity input power factor and greatly reduced input line current harmonic distortion due to nearly sinusoidal input line current attainable with controlled rectifiers.

Vector controller for a polyphase synchronous rectifier, method of vector-controlling a polyphase synchronous rectifier and synchronous rectifier incorporating the same

Abstract: A vector controller for a polyphase synchronous rectifier, a method of vector-controlling a polyphase synchronous rectifier, and a synchronous rectifier incorporating the vector controller or the method. In one embodiment, the vector controller includes: (1) an input line voltage detector configured to detect voltages on at least two rectifier input lines and produce therefrom a neutral excursion vector and (2) a neutral excursion compensator, coupled to said input line voltage detector, that applies said neutral excursion vector to a partially compensated drive vector to yield an excursion-compensated drive vector suitable for generation of excursion-compensated pulse-width modulated drive signals for said synchronous rectifier.

A low-power wide dynamic range envelope detector system and method

Abstract: An envelope detector system is disclosed for detecting an envelope in a system input signal. The envelope detector system includes an input node for receiving an input voltage signal, a transconducting amplifier for receiving the input voltage signal and producing an input current signal, a current mirror network for receiving the input current signal and for producing a current output signal, a capacitor for receiving the current output signal, and a rectifier output node for providing a rectifier output current signal. The capacitor is coupled to an input of the transconducting amplifier. The rectifier output current signal is fed into the current-mode wide-dynamic-range peak detector. The peak detector produces the envelope detector output current signal.

Switching electric source device

Abstract: A switching electric source device includes a first synchronous rectifier control circuit, which detects the resonance state developed based on the exciting energy of the primary winding after the main switching element switches off, and causes a first synchronous rectifier to switch on earlier during the time period from the completion of the resonance state to the switching on of the main switching element. Thus, the first synchronous rectifier switches on during the time period, and thus, current is prevented from flowing through a body diode, so that a voltage caused by the voltage drop in the body diode is prevented from being induced in the secondary winding and the third winding. As a result, variations in the output voltage, which is caused by the induced voltage of the third winding, can be prevented. The output voltage can be stabilized.

Synchronous rectifier gate drive shutdown circuit

Abstract: A power converter that includes a transformer, a bridge input circuit, a self-driven synchronous rectifier circuit, a gate drive circuit, and a gate drive shutdown circuit. The transformer includes a primary winding connected to the bridge input circuit, a first secondary winding, and a second secondary winding. The self-driven synchronous rectifier circuit is connected to the first secondary winding and includes a first synchronous rectifier for rectifying a voltage across the first secondary winding. The first synchronous rectifier includes a control terminal responsive to a voltage across the second secondary winding. The gate drive circuit includes a first diode connected to the control terminal of the first synchronous rectifier for introducing a dc level shift thereto. The gate drive shutdown circuit is connected to the first diode of the gate drive circuit and includes a switch for removing the dc level shift from the control terminal of the first synchronous rectifier when operation of the bridge input circuit is terminated.

Transimpedance amplifier with differential peak detector

Abstract: A method and apparatus to provide automatic gain control and offset correction in a transimpedance amplifier.

A novel driving scheme for synchronous rectifier suitable for modules in parallel

Abstract: This paper presents a driving scheme for synchronous rectifier, which maintains the performance of synchronous rectifier as self-driven, while solves the problem of short circuit when modules run in parallel. In addition, the amplitude of synchronous rectifier driving voltage can be adjusted by using the proposed scheme. So, it is more attractive in some occasions that the driving voltage is too high if self-driven is adopted. The principle of operation and the characteristics of the scheme are analyzed and verified on a 36 V/spl sim/75 V input 1.8 V/60 A output experimental prototype, whose size is 1/4 brick and efficiency is above 90% under rating condition.

A multilevel active front-end rectifier with current harmonic compensation capability

Abstract: This paper presents a multilevel active front-end rectifier that can absorb current harmonics generated by nonlinear loads connected to the same power distribution bus. That is, the proposed active front-end converter can operate as an active power filter and simultaneously as a rectifier. The control scheme is simple and forces the power system line current to be sinusoidal and in phase with the respective phase to neutral voltage, and is designed for the application in multilevel rectifiers. The control scheme is described in terms of principles of operations, dynamic modeling, and design. Simulated results are tested for steady state and transient operating conditions on a 10 kVA laboratory prototype.

An auxiliary-supply-assisted twelve-pulse diode rectifier with reduced input current harmonics

Abstract: Diode rectifiers have been widely used for an ac-to-dc converter. One of their problems is that they include large harmonic contents in its input current. A 12-pulse diode rectifier is useful for reducing them, but it still includes the (12m/spl plusmn/1)/sup th/ (m: integer) current harmonics in its input. In order to further reduce the input current harmonics a single-phase square wave auxiliary voltage supply is inserted in the middle dc bus of a 12-pulse diode rectifier. The purpose is to obtain a 12-pulse diode rectifier whose harmonic contents are equivalent to those of a 24-pulse diode rectifier. Theoretical analysis of the combined 12-pulse diode rectifier with the auxiliary supply is presented, and a control method of the auxiliary supply in accordance with the dc load current is proposed. The reduction in the harmonic contents in the output currents is verified by simulation and experimental results.

Capacitive moisture sensor

Abstract: A moisture sensing apparatus includes an oscillator for supplying an AC signal to a driven ring of a sensor having a pad inside the ring, and a ground plate around the ring. An amplifier forms part of a temperature-compensated, precision rectifier, and is connected to the pad. A first diode connected to the output of the amplifier in a feedback loop of the amplifier, where the amplifier nullifies temperature variation effects upon the diode, and supplies a rectified signal which is a function of moisture content of material in contact with the sensor. A second diodes is connected between the amplifier output and other input of the amplifier. The sensor has a rounded configuration to avoid electrostatic field fringing effects, and a passive impedance with both resistive and capacitive members is connected in parallel with the sensor to provide a functional baseline for the rectified signal.

An auxiliary-supply-assisted twelve-pulse diode rectifier with reduced input current harmonics

Abstract: Diode rectifiers have been widely used for an ac-to-dc converter. One of their problems is that they include large harmonic contents in its input current. A 12-pulse diode rectifier is useful for reducing them, but it still includes the (12m±1) th (m: integer) current harmonics in its input. In order to further reduce the input current harmonics a single-phase square wave auxiliary voltage supply is inserted in the middle dc bus of a 12-pulse diode rectifier. The purpose is to obtain a 12-pulse diode rectifier whose harmonic contents are equivalent to those of a 24-pulse diode rectifier. Theoretical analysis of the combined 12-pulse diode rectifier with the auxiliary supply is presented, and a control method of the auxiliary supply in accordance with the dc load current is proposed. The reduction in the harmonic contents in the output currents is verified by simulation and experimental results.

Multistage amplifier for rapid acquisition and random received signal power applications

Abstract: A method and apparatus for signal amplification and decision device operation on a signal which has a magnitude, peak value, or other average power that varies over time. In general, a peak detector detects the peak value of a received signal and responsive to the peak value, selectively enables a decision device when the signal is amplified to increase decision device accuracy. The decision may occur before the amplification forces the signal into saturation. Multi-stage amplification in combination with controlled switching or multiplexing may be utilized to selectively IO amplify the signal and selectively initiate decision device operation. The peak detector value may also control signal amplification levels in a multi-stage amplifier. Responsive to the peak value, a switch, which receives as its input the output from one or more amplifier stages, may be controlled to output the signal after a desired amount of amplification.

The investigation of PWM rectifier control method

Abstract: In general, power electric device is fed by AC/DC rectifier rather than by direct DC source and the inherent default of the rectifier has more bad influence on the power network. As a result, the PWM-rectifier has been paid more and more attention for unity input power factor, greatly reduced input line current harmonic distortion and bidirectional power flow capability. The paper present the topology of the main circuit, deduce the math model both in a-b-c and a - /spl beta/ reference frame, propose the direct current control scheme, get the current and voltage waveform and analyze the result of simulation which is processed by SIMULINK software on the base of math model.

Method of controlling half-controlled rectifier, and rectifier structure

Abstract: A method of controlling a half-controlled rectifier, and a rectifier structure, which comprises an n-phased half-controlled converter bridge, a DC intermediate circuit and a capacitor of the DC intermediate circuit. The converter structure further comprises an auxiliary intermediate circuit and a non-controlled n-phased diode rectifier bridge which feeds the auxiliary intermediate circuit and is connected to the DC intermediate circuit by isolating diodes.

Power converter for an electric engine start system

Abstract: An electric engine starting system includes a permanent magnet motor that is used to start the engine and then to generate power for powering a load while the engine is running. A disclosed system includes a first phase controlled rectifier in series with a power converter and a second phase controlled rectifier. During an engine starting operation, the first phase controlled rectifier is switched to couple the permanent magnet motor to a power source for starting the engine. Once the engine is running, the first phase controlled rectifier is switched off and the second phase controlled rectifier is switched on. The second phase control rectifier converts variable AC power from the motor into DC power. The power converter converts the DC power into an appropriate power for driving the load. One disclosed example includes a filter between the power converter and the load to ensure that the load receives a selected quality of power.

Self-excited induction generator with simple voltage regulation scheme for wind energy

Abstract: In this paper, a three-phase induction-machine-based wind power generation scheme is proposed. This scheme uses a low-cost three-phase diode bridge rectifier circuit connected to the induction machine via the AC load voltage regulator (AC-LVR) to transfer DC power with voltage regulation. The AC-LVR is used to regulate smoothly the output voltage of the three-phase self-excited induction generator (SEIG) connected to the diode bridge rectifier circuit. The excitation to the three-phase SEIG is supplied by a static VAr compensator (SVC) composed of the fixed excitation capacitor and the thyristor controlled capacitor. This simple method for obtaining a full variable-speed wind turbine system by applying a bi-directional power converter to a conventional induction generator is useful for wind power generation with a wide speed variation. The dynamic performance responses and the experimental results of a 5-kW 220-V three-phase SEIG directly connected to a three-phase diode bridge rectifier circuit at various loads are presented. Moreover, the experimental results of the PI closed-loop feedback voltage regulation scheme prove the practical effectiveness of this simple proposal for a wind turbine system.

Motor drive inverter control apparatus

Abstract: A motor drive inverter control apparatus includes a rectifier circuit for rectifying an AC power supply, an inverter circuit driven by an output from the rectifier circuit, a motor driven by an output from the inverter circuit, a first capacitor coupled in parallel to the output of the rectifier circuit, and a second capacitor coupled in parallel to the first capacitor via a diode. The second capacitor has capacitance not less than three times that of the first capacitor. Although the second capacitor shows a ripple content not less than 90% during practical use, it well absorbs regenerative energy produced by the motor. As a result, elements of the apparatus can be prevented from degrading caused by an over-voltage, and the apparatus can be downsized and reduced its cost.

Output voltage control of a synchronous rectifier

Abstract: The trend towards more digital signal processing in mains-powered devices causes an increasing variety of supply voltages at ever decreasing levels and at higher currents. At present, the secondary side architecture provides a separate ac-dc conversion and dc-dc down-conversion stages in order to obtain stabilized voltages at those low levels. According to the present invention, a controlling synchronous rectifier is provided, comprising a power MOSFET and a control unit which allow to integrate both stages. In particular, according to the present invention, the output voltage of the synchronous rectifier is controlled by controlling the channel switching of the MOSFET. Advantageously, this provides for a very simple and efficient rectification and voltage control.

Protection method for power circuit, and its device

Abstract: PROBLEM TO BE SOLVED: To easily and surely detect the presence or absence of a supply voltage abnormality and perform control necessary for protecting a component of a power supply circuit. SOLUTION: A three-phase full-bridge diode rectifier circuit 3 whose input terminal is connected to a three-phase AC power source 1 via a main relay 2 and a reactor 4 between output terminals of the three-phase full-bridge diode rectifier circuit 3 are provided. A capacitor 5 connected via the input terminal, a PWM (pulse width modulation) inverter 6 that receives the voltage across the capacitor 5 as an input, one output terminal of the three-phase full-bridge diode rectifier circuit 3, and a corresponding terminal of the capacitor 5. A current detection unit 8 including a current transformer, an abnormality detection unit 9 for detecting an abnormality by inputting the detected current value, and outputting an abnormality detection signal, and a PWM inverter with an inverter input voltage as an input 6 is controlled, and each switching element of the PWM inverter 6 is connected to the three-phase And an inverter control unit 11 for controlling to cause the supply voltage abnormality addressed the bridge diode rectifier circuit 3. [Selection] Figure 1