Showing papers on "Rectifier published in 1983"

A Quantitative Analysis of Induction Motor Performance Improvement by SCR Voltage Control

Abstract: Minimum input power and maximum efficiency operation occur at characteristic slip values which can be realized for any induction motor operating at part load by properly adjusting the amplitude of the applied stator terminal voltages. These two criteria are shown to yield perceptibly different results when the motor is driven from a silicon-controlled rectifier (SCR) voltage controller. In addition, it is demonstrated that a constant power factor controller results in an operating regime which is substantially poorer than operation at either minimum input power or maximum efficiency. It is further shown that minimum stator current and minimum power factor angle criteria yield results which are closer to the ideal than the constant power factor controller.

Reduction of harmonics in gas discharge lamp ballasts

Abstract: A gas discharge lamp ballast circuit operates at high frequency and is fed from a mains supply through a rectifier having a smoothing capacitor. The invention provides for the load to include an inductor and to return to the rectifier supply at a position isolated from the smoothing capacitor by one or more diodes, and for there to be a discharge path from the smoothing capacitor through the load to charge a control capacitor, and lower the load voltage to allow a rectifier current flow to the load. The smoothing capacitor is charged by current flowing from the inductor during a relaxation phase, to a voltage higher than the peaks of the rectifier. The smoothing capacitor voltage is maintained by proportioning the control capacitor size to cause rectifier current, and not smoothing capacitor discharge, to supply circuit and load losses.

Analog telemetry system for biomedical implant

Abstract: An analog data transmission circuit for a biomedical implant employs a linear amplifier to modulate the impedance of a resonant circuit tuned to an externally generated constant carrier frequency. The resonant circuit comprises a tuned coil in circuit with a linear modulating switch and a digital modulating switch. The digital switch is gated by the digital data output from digital control circuitry within the implant. The linear amplifier output drives the linear modulation switch. The switches are preferably matched pairs of MOSFET's of opposite polarity having complementary parasitic diodes which form a phantom diode bridge. The bridge acts as a full wave rectifier and boosts the bias voltage on the sources of the FET pair forming the linear modulation switch such that the radiated amplitude is independent of the distance of the programming head. A timed power-up circuit supplies power to the amplifier and starts a square wave calibration period in response to the approach of the programming head. For ICEG transmission, a charge dump circuit depolarizes the lead before it is coupled to the amplifier.

Device for detecting metallic objects in a flow of non-metallic material

Abstract: A device for detecting metallic objects in a material flow, comprising as sensing member a scanning coil consisting of a primary coil and, for example, two oppositely connected secondary windings arranged symmetrically around the primary winding so that the voltage induced in the secondary winding becomes zero as long as no conducting objects appear in the scanning area. To eliminate irrelevant signals from conducting objects in the vicinity of the scanning coil but not in the material flow or from weakly conducting objects in the material flow, the primary winding is fed with at least two alternating currents having different frequencies. The corresponding secondary voltages are rectified in phase-controlled rectifiers, and in a calculating circuit the difference is derived between the output of one rectifier voltage and the output of another rectifier multiplied by a constant factor which includes the relation between the frequencies of the corresponding alternating voltages.

Power supply device

Abstract: A power supply device includes a plurality of switching regulators and a waveshaping circuit, or, a switching circuit for converting an input voltage to switching pulses, a transformer for transforming the voltage of the pulses generated in the switching circuit, a rectifier circuit for rectifying the switching pulses provided through the transformer, a switching regulator into which the resulting dc input is supplied from the rectifier circuit and a waveshaping circuit The former waveshaping circuit shapes the waveform of switching pulses generated within one switching regulator of the plurality of switching regulators and supplies the shaped output to the other switching regulators as an input reference waveform The latter waveshaping circuit shapes the waveform of the switching pulses provided from the transformer and supplies the resulting function waveform to a pulse control unit in the switching regulator as an input reference waveform In the case of a plurality of switching regulators of the separately excited type, a reference waveform supplied each switching regulator may be provided from a common waveform generator

Novel topological alternatives to the design of a harmonic-free, utility/DC interface

Abstract: Circuit designs previously proposed for utility/DC power conditioning interfaces that draw a harmonic-free, unity power factor ac current have, for the most part, followed a certain topological approach. This paper discusses several alternative approaches that can greatly improve the interface's simplicity, performance, and cost. One suggestion involves the use of a dc current source instead of a voltage source. Another concerns the use of a tuned passive filter to remove the ripple from the dc system's waveforms. Results from an experimental 6 kW rectifier are included to demonstrate the feasibility and usefulness of the approaches suggested.

Class-E resonant regulated DC/DC power converters: analysis of operation, and experimental results at 1.5 MHZ

Abstract: We present analytical results, design considerations and experimental results at 1.5 MHZ, for a novel, resonant, high-frequency de/de converter. The circuit works virtually without dynamic losses at several-MHz switching frequency. The analysis gives the permissible area of the equivalent load impedance for lossless operation, presents a model for regulation by narrow-band frequency control, and characterizes the output full-wave rectifier. Experimental data from a 1.5-MHz, 40-W converter verify the results of the theoretical analysis. The measured efficiency was 85%.

Bridge rectifier circuit

Abstract: A bridge rectifier circuit comprises a bridge of switching transistors 1 to 4 having their control terminals connected to switch the transistors to provide either full wave rectification of an a.c. input voltage or polarity correction of a d.c. input voltage of either polarity appearing at terminals A and B. The switching transistors are all of the same polarity type and at least two floating drivers 6 and 7 are connected to generate and supply control potentials to the control terminals respectively of a pair of the switching transistors. In a preferred embodiment the switching transistors comprise field effect transistors. The floating drivers can comprise at least one respective bridge rectifier 12 capacitively linked to a source of voltage pulses 10 when the input voltage has a predetermined polarity, to generate the control potentials. Alternatively the floating drivers can comprise a voltage doubler or quadrupler capacitively linked to the source of voltage pulses. Such bridge rectifier circuits can be employed in a telephone instrument.

Circuit arrangement for operating a high-pressure gas discharge lamp

Abstract: A circuit arrangement for operating a high-pressure gas discharge lamp (3) with a pulsatory direct current produced from an alternating voltage supply (A, B) via a full-wave rectifier (1). The output of the full-wave rectifier is shunted by a series arrangement of a diode (4) and a capacitor (5). The capacitor (5) has a value of 10 nF to 1 μF and a resistor (6), which is high-ohmic with respect to a current limiter (2) in series with the lamp (3), is connected in a current circuit between the end of the capacitor facing the diode and the lamp (3). As a result, a low re-ignition voltage is attained during the head-up phase of the lamp.

A Microprocessor-Based Controller for a Three-Phase Controlled Rectifier Bridge

Abstract: A complete design of a microprocessor-based control circuit for a three-phase controlled rectifier bridge is presented. The Motorola M6802 microprocessor is used, and a flowchart and program listing are provided. Practical problems such as synchronization with noisy references are discussed, and modifications to the basic program are indicated. The basic control' philosophy developed can be extended to. the entire class of phase controlled systems, e.g., cyclo- converters, ac-voltge controllers, etc.

Variable speed AC motor control system

Abstract: AC mains voltage input is directed to a bridge rectifier and converted to a DC voltage output. This DC power supplies an inverter which reconverts it to variable frequency AC output, used to drive a variable-speed AC motor. A microprocessor-based control unit generates firing pulses for SCR's in both the rectifier and inverter. It maximizes the efficiency of the rectifier by generating phase delay and sequencing data in advance of each line-to-netural zero-crossover of the AC mains voltage input; it makes the voltage and frequency of the inverter AC output both proportional to the value of the DC voltage output, enabling the system to maintain a constant volts/Hertz ratio between the AC output voltage and the AC output frequency. Appropriate fault protection circuits are included with the control unit to prevent fault conditions from damaging the system.

Vehicular direct-current three-wire electric system

Abstract: A vehicular charging and starting system is improved by providing first and second a.c. generators, rectifiers and voltage regulators, the negative terminal of the first rectifier and the positive terminal of the second rectifier being connected to a neutral or body grounded conductor. A pair of batteries are respectively positively and negatively connected to said neutral or grounded conductor. Protection circuits may be provided for overcurrent protection of the rectifiers or electrical loads, and for preventing the starter motor from rotating at an excessive speed once the engine is started.

The Newton-Raphson Load Flow Applied to AC/DC Systems with Commutation Impedance

Abstract: Existing conditions in industrial ac-dc power systems may result in significant commutation resistances. If the resistance to reactance ratio of the commutation impedance is high, significant errors can result in load-flow studies which neglect the resistive portion. A method is presented for inclusion of a resistance-inductance fed bridge rectifier in a Newton-Raphson (N-R) load flow program. Polar form of the power flow equations is assumed. An example problem is provided for comparison.

Bidirectional insulated-gate rectifier structures and method of operation

Abstract: Bidirectional IGR structures include MOS gates at both the device anode and the device cathode, thereby allowing control of current conduction for both polarities of applied voltage. The bidirectional structures may alternatively be operated in an active anode shorting mode whereby higher switching speeds are achieved without either the loss of reverse blocking capability or decrease in forward current density.

Variable frequency induction generator

Abstract: The invention is a combination induction generator/synchronous generator power system which finds particular use in aircraft environments. The power system includes an induction generator (36) and a tandem generator (38) enclosed in a single housing (34). The tandem generator (38) includes a tandem synchronous generator (46) which optionally excites the induction generator (36) or provides power to the aircraft systems upon activation of the three-phase contactor (48). The tandem generator (38) also includes a tandem synchronous generator (44) which produces, via a phase controlled rectifier bridge (42), 270 VDC power for the aircraft systems.

Capacitive discharge drive for electric stapler

Abstract: An electrically operated stapling apparatus is disclosed having a circuit utilizing a capacitor for driving the solenoid actuator for the apparatus. The circuit includes a fullwave rectifier for charging the capacitor with closely spaced dc pulses and includes circuitry for producing a plurality of charging levels for the capacitor depending upon the number of sheet material to be stapled. A reference circuit is also provided to insure the voltage level of charging is such that the operation of the apparatus is immune to line source voltage fluctuations.

Apparatus for operating HID lamp at high frequency with high power factor and for providing standby lighting

Abstract: Ballast apparatus operates a HID lamp at high frequency and high power factor. Series-connected current-limiting input inductor and input capacitor connect across apparatus input and are tuned off resonance to pass predetermined lagging current. An additional input capacitor is connected across input terminals to that input power factor approaches unity. Full-wave diode bridge has input connected across series-connected input capacitor and filter capacitor connects across bridge rectifier output. During normal operation, the filter capacitor develops a DC potential which is current limited by series-connected inductor and capacitor. Inverter has input connected across filter capacitor and inverter an output that drives the HID lamp through a high-voltage generating and variable impedance resonant circuit. When HID lamp is not operating, resonant circuit impresses high voltage across lamp to start same in warm or cold condition and resonant circuit exhibits relatively low impedance which decreases current-limited potential across filter capacitor. When HID lamp is normally operating, resonant circuit exhibits relatively high impedance which increases DC potential across filter capacitor. Additional pair of series-connected diodes connect across bridge rectifier output and incandescent lamp connects between predetermined input terminal and voltage responsive control and switching means, which connects to interconnection of additional diodes. Voltage responsive switching means responds to decreased voltage across filter capacitor when HID lamp is not operating to energize standby incandescent lamp. When HID lamp is operating, voltage-responsive switching means responds to increased voltage across filter capacitor to maintain incandescent lamp de-energized.

Television receiver standby power supply

Abstract: In a power supply for a remote controlled television receiver, a bridge rectifier includes first and second unidirectional current conducting devices, an output terminal, a current return terminal and two input terminals. A remote control circuit generates an on/off command signal. A source of alternating voltage available during both states of the command signal is coupled between the two input terminals. A first direct voltage is developed between the output and current return terminals during both the on and the off states of the command signal upon alternate conduction of the two unidirectional current conducting devices. A first power supply is coupled between the bridge rectifier output and current return terminals and is responsive to the command signal for developing an operating potential from the first direct voltage only during the on-state of the command signal. A load circuit is energized by the operating potential to draw power from the bridge rectifier output terminal. The remote control circuit is energized by a standby DC power supply that employs one of the bridge rectifier unidirectional current conducting devices to develop a second, lower magnitude direct voltage that energizes the remote control circuit during both the on and off states of the command signal. The standby power supply includes a filter circuit having an input terminal coupled to one of the unidirectional current conducting devices of the bridge rectifier for half-wave rectifying and filtering the alternating voltage. The second direct voltage is developed between the filter output and current return terminals.

Electronic still camera

Abstract: PURPOSE:To realize electronically easily the shutter speed extending from an ultra-high speed to a comparatively low speed by providing a gate circuit between a photoelectric conversion section and a storage transfer section of an image pickup element, adjusting the opening time of the gate circuit to control the exposure time substantially. CONSTITUTION:Light emitted from an object is made incident to the photoelectric conversion section of a solid-state image pickup element 13 via a lens 11 and aperture blades 12. The photoelectric conversion section generates a current in response to the light and this current goes to an output video signal of the element 13 for only the gate pulse's width inputted via a buffer circuit 20 from a gate pulse generating circuit 18. This video signal is outputted from an output terminal 23 after the amplification, and required conversion and compensation are done at a video processing circuit 14. This video signal is branched, the photometric area is limited at a photometric area selection circuit 15, rectified at a rectifier circuit 16, compared with a reference voltage at a comparison amplifier circuit 17 and a positive voltage is outputted when the video output is larger than a suitable value and a negative voltage is outputted when smaller. A gate pulse generating circuit 18 changes the gate pulse width in response to the output of the circuit 17.

Controller of pwm inverter

Abstract: PURPOSE:To reduce the magnetic sound of a motor on the basis of a PWM control by varying the hysteresis width of comparing means having hysteresis characteristic for comparing a current command signal with a current detection signal by an AC signal such as a triangular wave. CONSTITUTION:An induction motor 4 is driven by a PWM inverter 3 connected to a rectifier 1. A current command signal iu*, iv* formed of a speed command 14 and a signal of a speed detector 5 and iw* added by an adder 7, and a signal added by an adder 9 with the signals of current detectors 8U, 8V are applied to comparators 10U, 10V, 10W having hysteresis characteristic, an inverter 3 is controlled to be fired, and a triangular AC signal from a signal generator 12 is applied to a hysteresis width regulator 13 to regulate the hysteresis width of the comparators 10. Accordingly, the harmonic waves of the motor current are reduced, the magnetic sound of a motor can be largely reduced particularly at the low speed rotation time.

Electronic ballast for fluorescent lamps

Abstract: The electronic ballast for supplying a fluorescent lamp (25) has a push-pull switch arrangement (15, 16) which drives an operating tuned circuit (18, 19) for the fluorescent lamp (25) in the correct phase. The push-pull switch arrangement (15, 16) controls a further series tuned circuit (30, 31) which supplies the capacitor (14) of a DC voltage supply circuit via a coil (33) and a second rectifier circuit (34).

Voltage loss sensor and alarm

Abstract: A sensor for monitoring loss of voltage on a monitored conductor includes first and second capacitors, each of which is charged by a rectifier circuit which derives operating power from the monitored conductor. Upon loss of voltage on the conductor, a discharge circuit discharges the first capacitor, while allowing the second capacitor to remain charged. When the voltage difference between the two capacitors exceeds a predetermined threshold level, an SCR discharge circuit discharges the second capacitor to provide an output signal.

Electronic ac induction motor brake

Abstract: A braking control circuit for an alternating current motor is disclosed as having a winding and adapted to be coupled to an energizing control circuit for connecting a source of AC voltage to and for disconnecting the source of AC voltage from the winding. The braking control circuit comprises a selectively controlled rectifier operative in a first conductive mode for applying rectified current to the winding to brake the motor and in a second non-conductive mode, and a switching circuit coupled to the rectifier and responsive to the disconnecting of the source of AC voltage from the winding for switching the rectifier between its first and second modes at a first switching rate to brake the motor rotation at a corresponding first braking rate, and thereafter for switching the rectifier between its first and second modes at a second switching rate different from the first switching rate to brake the motor at a corresponding second braking rate.

Full-wave rectifier circuit

Abstract: In a full-wave rectifier circuit, a sinusoidal signal is applied to a differential amplifier, first and second current mirror circuits obtain outputs from the differential amplifier which are opposite in phase to each other. Outputs of the first and second current mirror circuits are applied respectively to the input and output sides of a third mirror circuit and other outputs of the first and second current mirror circuits are applied respectively to the input and output sides of a fourth mirror circuit. The connecting point of the first and fourth current mirror circuits is connected to the base of a first emitter-follower-connected transistor, while the connecting point of the second and third current mirror circuits is connected to the base of a second emitter-follower-connected transistor. The connecting points are connected to a current source circuit. The first and second emitter-follower-connected transistors have their emitters connected together, to provide a full-wave-rectified output.

Alternator-rectifier unit with economical connections to wires embedded in a circuit board

Abstract: A wire conductor embedded in a circuit board for interconnecting rectifier diodes passes through a cut-out of the circuit board and is bent out of the cut-out beyond the surface of the circuit board so as to provide a U-shaped connection piece in which the end of a generator winding wire can be laid and clamped until it is soldered. The U-shaped connection piece can also be provided by a clip affixed to the embedded wire where it is accessible in a cut-out of the circuit board.

Illumination installation, especially for use underground in mining

Abstract: The invention relates to an illumination installation, especially for use underground in mining, in which fluorescent tubes (13) are operated with a high-frequency voltage, the high-frequency being generated in the housing (12) of the light, and the supply voltage being generated in a rectifier power supply (2), and energy being transferred between the DC power supply and the housing (12) of the light via an intrinsically safe DC cable (8).

Electronic tripping circuit for a delayed fault current protection circuit

Abstract: The fault current protection circuit comprises a current transformer, which detects the fault current and whose secondary winding (1) supplies a rectifier bridge circuit (3) downstream of which there are connected an energy storage device (7) and a time-delay circuit (8, 12, 13), by means of which a switching device (14) is driven which is connected in series with the coil winding (17) of a tripping device. The bridge circuit (3) contains semiconductors (5) which protect the circuit against overvoltages. The time-delay capacitor (13) is charged via a constant-current regulating element (8). The switching device (14) is connected to a reference voltage (23) which is formed by a resistor (19) and a zener diode (20).

Rf power switches

Abstract: RF switches, for use with radio frequencies, are fast, and require practically no DC energy for maintaining the ON and OFF positions. The switches include a rectifier in series with a capacitor, or with another rectifier in a back-to-back position, or facing each other, or a transistor instead of these two, the rectifier and transistor having an adequate reverse recovery time, these elements being arranged between the RF power source and the load. An inductive element is disposed in series with either the elements of the switch or between the base of the transistor and ground. There may be provided a further diode in series with the inductive element and the switch and in the connection to ground.

Input regulated high voltage D.C. power supply system

Abstract: According to the invention, the system comprises a resonance type inverter, a diode rectifier bridge and single regulation loop controlling controlled switching means, forming a chopper, interconnected between the rectifier bridge and the inverter. The system is applied to X-ray equipment.

Full-wave rectifier for CMOS IC chip

Abstract: A full-wave rectifier is implemented in CMOS integrated circuit chip technology. Two transistors are used in a bridge arrangement with two diodes to implement the rectifier while avoiding parasitic transistor action which previously provided an unwanted current path through the chip substrate to defeat full-wave rectification.