Showing papers on "Flyback converter published in 1985"

A Novel Sinewave in AC to DC Converter with High-Frequency Transformer Isolation

Abstract: A novel Switch-Mode-Rectifier (SMR) structure is proposed and analyzed in this paper The proposed converter structure employs a high-frequency sine PWM cycloconverter to provide high-frequency ohmic isolation between the source and the load Furthermore, it draws high-quality current from the ac source thus requiring only small input reactive components Consequently, the proposed converter structure exhibits high power density and has low implementation cost

DC-AC inverter with overload driving capability

Abstract: A DC-AC inverter includes a bridge converter for converting an input DC into an output AC signal which uses field-effect transistors in the bridge circuit. The characteristics of the field-effect transistors enable the bridge converter to temporarily supply power in significant overload conditions. A DC-DC converter may also be included between the DC power source and the bridge converter to provide voltage boosting, when required. Field-effect transistors are also included in the DC-DC converter for power switching. The duration and amount of overload current output by the bridge converter is monitored and when an overcurrent condition beyond a predetermined amount or duration is detected, the bridge converter is disabled. The bridge converter is reenabled at a predetermined time thereafter. A plurality of field effect transistors may be connected in parallel at each location wherein a solid state power switching device is used in the inverter to thereby multiply the power handling capacity of the inverter as a whole.

Power converter for AC load

Abstract: A power converter that drives an AC motor includes a main circuit and a control circuit such that the main circuit includes a forward conversion circuit that forwardly converts AC power from an input AC power source into DC power, and an inverter circuit that inversely converts the thus forwardly converted and smoothed DC power into AC power of a specified voltage and frequency; the control circuit includes a calculation device that calculates a torque current component of the AC motor, a detection device that detects occurrence of an instantaneous interruption in the AC power source, a command device that commands a frequency to be fed into the AC motor, a control device that receives a signal relative to an output signal of the command device, so as to control a terminal voltage of the AC motor, and a compensation device that adjusts the output signal of the command device so that the output signal of the calculation device is caused to be substantially zero in response to the output signal of the detection device.

Power converter apparatus and control method thereof

Abstract: A power converter apparatus has at least two converters CONV1 and CONV2. The DC side of each of the converters CONV1 and CONV2 is connected to a filtering capacitor Cd which serves as a DC power source for a load device LOAD. The AC side of the converter CONV1 is connected to the secondary winding of a first transformer TR1. The AC side of the converter CONV2 is connected to the secondary winding of a second transformer TR2. The primary winding of transformer TR1 is connected in series to the primary winding of transformer TR2. The series circuit of the primary windings of transformers TR1 and TR2 is coupled to an AC power supply SUP via a single AC reactor Ls. A control method of the invention is adapted to the power converter apparatus in which plural PWM converters are used. The phase of a modulating wave (carrier) of one PWM converter differs by a predetermined degree from that of another PWM converter.

A DC to 3-Phase Series-Resonant Converter with Low Harmonic Distortion

Abstract: A type of dc to 3-phase series-resonant converter (s.r.converter) or potentially submegawatt industrial applications is presented. The converter provides variable-frequency sine-wave currents, with low harmonic distortion at the output terminals, and with the frequency ranging from -200 through dc to +200 Hz. The converter can transfer power in both forward and reverse power-flow directions to almost any type of load circuit. The methods of control are formulated such that they can be implemented easily with high-speed logical circuits. Test results for a 1-kW demonstration converter are supplied.

Charging control system in solar generating device

Abstract: PURPOSE: To obtain a charging control system high in working efficiency by removing a DC/DC converter when the ratio between the input voltage and the output voltage of the DC/DC converter is kept between the conversion efficiency of the DC/DC converter and the reciprocal of said conversion efficiency. CONSTITUTION: When an accumulator 3 has a level less than a full charge mode, the DC voltage generated by a solar battery 1 is raised or dropped via a DC/DC converter 5 after a switch 12 is closed. Then a charging current and a load current are supplied to the accumulator 3 and the load 4 respectively in response to the output voltage of the converter 5. While the rise and drop are nor required for the output voltage of the battery 1 by the function of the converter 5 when the ratio between the output voltage V 0 and the input voltage V i of the converter 5 is kept between the conversion efficiency FC of the converter 5 and its reciprocal 1/FC. Thus an input/output voltage comparison control circuit 9 opens the switch 12 and separates the converter 5 from the load 4. COPYRIGHT: (C)1987,JPO&Japio

The application of power MOSFETs at 10MHz

Abstract: The design and performance of a 10MHz dc/dc converter is discussed. The behavior of the power MOSFET at this frequency, and the integration of device parasitics into the circuit are described. The performance of a 50W converter is compared with the predictions of a detailed simulation. Losses are analysed and shown to be dominated by MOSFET switching.

DC/AC converter for feeding a metal vapour discharge tube

Abstract: The invention relates to a DC/AC converter (30 to 72) for feeding a low-pressure mercury vapour discharge tube (15). The converter comprises two series-connected main transistors (11 and 20) which in the operating condition are alternately conducting. According to the invention, the conduction times of the two transistors (11 and 20) are always kept equal to each other by means of an auxiliary circuit (70 to 72, 32a, 32b, 32c), whereby the operation of the timing circuit (32, 33) is influenced. Thus, inter alia no cataphoresis occurs in the lamp (15).

Current-source power converting apparatus with self-extinction devices

Abstract: A current-source power converting apparatus having a three phase AC-DC converter composed of self-extinction devices for converting an AC power furnished from an three phase AC power source into a DC power and a DC-AC inverter connected with the AC-DC converter through a DC reactor for re-converting the DC power into a three phase AC power to supply the re-converted power for a load. When the failure of the AC power source is detect according to one embodiment, the AC power source is detached from the AC-DC converter and a battery is connected between arbitrary two phases at the input end of the AC-DC converter. After that, the DC power of the battery is supplied for the DC-AC inverter intermittently by switching the corresponding self-extinction devices of the AC-DC converter and controlled by varying the duty ratio of the switching operation.

Method and system for controlling an AC-DC converter system

Abstract: In control of an AC-DC converter system including AC-DC converters (1A, 1B) having respective AC terminals connected to AC power systems (6A, 6B) and having respective DC terminals connected to each other, a fault in the AC power systems is detected, and upon occurrence of a fault in any of the AC power systems, the DC current of the AC-DC converter which is connected to the sound AC power system is adjusted in such a manner as to maintain the AC voltage of the AC-DC converter which is connected to the sound AC power system at a desired value.

Communication receiver system having a voltage converter with an operating frequency below the receiver IF

Abstract: A communication receiver system for receiving coded signals and of the type having at least one predetermined intermediate frequency (IF) signal comprising a decoder for detecting and decoding the received coded signals and a DC/DC voltage converter circuit, connected to the decoder, for generating a voltage greater than the supply voltage of the communication receiver system at a frequency below the frequency of the IF signal. The system further comprises a frequency trim circuit, connected to the voltage converter circuit, for controlling the operating frequency of the DC/DC voltage converter circuit whereby interference with the IF signal is prevented.

Switched power supply comprising a free-running flow converter and electrically separated control loop

Abstract: A switched power supply has a rectifier arrangement for generating a DC voltage from an input AC voltage. A converter arangement in the power supply has a switching transistor and a transformer. The converter arrangement is designed as a free-running flow converter, whereby the switching transistor is switched on in the current-free condition. A control stage with an electrically separated control loop is provided at the secondary side, whereby the control stage acquires the deviation of an output DC voltage from a prescribed value and sets the pulse duty factor for the switching transistor via the control loop.

Control apparatus of ac/dc power converter

Abstract: In the control apparatus of an AC/DC power converter, the occurrence of a single-phase line-open in the AC power line is detected by an open-circuit detector (14) so that a detection signal (E14) is generated. The control angle (a) of a converter (3) on the side of occurrence of the single-phase line-open is kept at a given value (a - 80 or 110 degrees) based on the detection signal (E14). At the same time, the current set value of the automatic current regulator (8) is also kept at a fixed value (E21) based on the detection signal (E14).

Focus voltage circuit for television apparatus

Abstract: The retrace pulse voltage developed by a horizontal deflection generator is applied to the primary winding of a flyback transformer. The voltage across a high voltage winding of the flyback transformer is rectified and filtered to produce an intermediate, DC high voltage. The voltage developed across the flyback transformer primary winding produces a leakage flux that links the winding turns of a coil in a dynamic focus circuit. The coil and a capacitor form an LC resonant circuit that waveshapes the induced voltage in the coil to produce a sinusoidal or an approximately parabolically shaped horizontal frequency voltage. The intermediate DC high voltage and the parabolically shaped horizontal frequency voltage are summed to produce the focus voltage.

Wide-band high voltage amplifier for telephone exchange subscriber line interface utilizing low voltage control circuitry

Abstract: A wide band high voltage and high power amplifier is particularly useful for telephony applications. The amplifier employs a flyback converter with the capacitor storage element coupled across the line. The subscriber line is characterized in having a definite load impedance which impedance is in parallel with the storage capacitor of the flyback converter. The subscriber lines are monitored by a differential amplifier which provides a single-ended output indicative of the levels across the lines. This output is summed with the input signal to develop an error signal. The input signal to the line circuit is the particular signal of concern such as ringing, the voice signal and so on. The error signal is supplied as one input to a comparator having another input coupled to a triangular reference waveform. The output of the comparator provides a pulse width modulated waveform where the width of the pulses are indicative of the error signal. These pulses are applied to a transistor coupled to the primary winding of the transformer associated with the flyback converter to enable flyback operation during the pulse and hence to transfer energy to the storage capacitor as a function of the error signal.

Opto-electrical signal converter with stabilization

Abstract: The invention relates to an opto-electrical signal converter for linearly converting a signal consisting of an alternating current superimposed on a direct current into a signal consisting of an alternating voltage superimposed on a direct voltage. Such a converter comprises the combination of a light diode and a photosensitive element optically coupled therewith, which combination is designated as optocoupler. The invention has for its object to provide a converter having a good linear signal transmission, the value of the output signal of the converter being independent of the properties of the optocoupler used. For this purpose, the converter is provided with a transistor, of which a semiconductor junction connected to the base of the transistor is AC-connected parallel to the base-emitter junction of the transistor and is DC-connected in series with a stabilization circuit. As a result, a linear AC and DC transmission, respectively, is reached independently of ageing and of the temperature behaviour of the optocoupler used.

Electronic ballast with low frequency AC to AC converter

Abstract: A gas discharge lamp is started with a high frequency AC signal from an oscillator and then operates on a low frequency AC signal provided by an AC to AC converter synchronously with the AC supply line. The low voltage switching devices of the converter are protected from the high voltages of the high frequency oscillator by locking the converter in a single phase during starting.

Switch-mode power supply having a free-running forward converter

Abstract: A switch-mode power supply has a rectifier for producing a small d.c. voltage from an input a.c. voltage, and a converter which comprises a switching transistor and a transformer. The converter arrangement is a free-running conductive converter and the switching transistor is switched on in the currentless state.

Apparatus for generating a multi-frequency signal

Abstract: An appartus for generating a multi-frequency signal includes a D/A converter, two converter circuits connected to the D/A converter for determining a respective connecting instant, two controlled waveform counters each being connected to a respective one of the converter circuits, a D/A cycle control connected to the converter circuits for monitoring the converter circuits, a sample-and-hold circuit having divider capacitors and being connected to the D/A converter, and holding capacitors connected to the sample-and-hold circuit.

Reactive power to DC signal converter

Abstract: The output from a capacitor, which shifts a voltage output by π/2, and a detected frequency output, are multiplied by a pulse width modulation circuit, and a current input is switched by the multiplied output to convert a reactive power to a corresponding DC signal. The converter has improved frequency characteristics.

DC/AC converter for igniting and operating a discharge lamp

Abstract: A DC/AC converter (8) having a half bridge circuit for igniting and feeding a gas and/or vapour discharge tube (1). A starting capacitor (94) of this converter is connected between a junction (A) between two branches--each comprising a semiconductor circuit element (60 and 61)--of the half bridge circuit on the one hand and a center tapping (E) of a voltage divider (90, 91) on the other hand. As a result, the converter (8) starts satisfactorily and hence the discharge tube (1) readily ignites, moreover undesired starting pulses during the operating condition are avoided.

A novel sine wave in AC to DC converter with high frequency transformer isolation

Abstract: A novel Switch-Mode-Rectifier (SMR) Structure is proposed and analyzed in this paper. The proposed converter structure employs a High-Frequency Sine PWM cycloconverter to provide high frequency ohmic isolation between the source and the load. Furthermore, it draws high quality current from the AC source thus requiring only small input reactive components. Consequently, the proposed converter structure exhibits high power density and has low implementation cost.

Remote Power Feeding of ISDN-Terminals at the Basic Access

Abstract: In this paper some principles of power feeding are discussed. For power supply of digital telphone sets the use of a DC/DC converter is a reasonable solution. With the implementation of the DC/DC converter into the terminal some problems must be solved like noise problems, decoupling problems and stabilized operation. A realization of a DC/DC converter is shown which has a good efficiency with loads from 10 mW to 1W. The converter can be used for the S -interface as well as for the U-interface in PABX applications.

Power supply with free oscillating forward converter and electrically insolated control loop

Abstract: The invention relates to a switching power supply having a rectifier arrangement (BG) for generating a DC voltage (UG) from an alternating input voltage (UE), and having a switching transistor (T1) and a transformer (U) having converter arrangement. According to the invention provides that the converter arrangement is designed as a freely oscillating forward converter, wherein the switching transistor (T1) is turned on in the currentless state, and in that a secondary-side regulating stage is provided with an electrically isolated control loop, wherein the control step, the deviation of a DC output voltage (UA) of a predetermined detected value, and adjusts via the control loop, the duty ratio for the switching transistor (11).

Switched power pack with free-wheeling flow converter and switched controller at a secondary side

Abstract: A switched power supply has a rectifier arrangement for generating a DC voltage from an input AC voltage. A converter arrangement thereof has a switching transistor and a transformer. The converter arrangement is designed as a free-running flow converter wherein the switching transistor is switched on in a current-free condition. A secondary side of the converter arrangement comprises a secondary switch controller which is synchronized by the transformer and which regulates an output DC voltage.

Ferrite substrates for high-frequency switching DC-to-DC converter applications

Abstract: A hybrid IC of small capacity DC-to-DC converter was formed on a ferrite substrate which also serves as a core for inductors. The converter has characteristics of 80% in efficiency, 1.2 W/cm3in output power and a switching frequency of 500 kHz. To optimize both the magnetic property and mechanical strength of the substrate, a Ni-Cu-Zn ferrite was employed and LiO 2 and WO 3 were added to improve high mechanical strength.

Circuit arrangement for a flyback converter switched-mode power supply

Abstract: The flyback converter contains a switching transistor (Tr1) which is driven by an integrated circuit (IS). This circuit receives its supply voltage during the blocking phase from a winding (supply winding 3/4) on the primary side. A further winding (control winding 5/6) on the primary side supplies the control variable for the integrated circuit (IS) during the flow phase. It is proposed to connect the supply input (9) of the integrated circuit (IS) via a transistor (Tr2) and a diode (BY 360) to the control winding (3/4), and to bias the transistor base via a zener diode (Z11). In the starting phase, in which the voltage of the supply winding (3/4) initially builds up, this circuit supplies the required operating voltage, and switches off again when the power supply is in the steady state. Main field of application: switched-mode power supplies with an expanded mains voltage range.

High voltage generator for television apparatus

Abstract: OF THE DISCLOSURE A high-voltage stabilizer circuit cooperates with the flyback transformer in a cathode ray tube display system to prevent level variations in the video signal from producing corresponding variations in the high-voltage output from the flyback transformer to the cathode ray tube, such high-voltage variations being undesirable because they result in changes in the electron beam position on the phosphor screen that produce shifts in the resultant picture. The current flowing through the video circuit is controlled inversely in relation to variations in the cathode current of the cathode ray tube so that the high-voltage output from the flyback transformer remains constant. This high voltage stabilizer involves specific choices of circuit element values and is particularly suitable for so-called flat-tube television receivers.

Circuit arrangement for harmonic-free DC voltage supply of a load from an AC voltage source via a converter and an active filter

Abstract: In order to produce a harmonic-free voltage of alternating polarity with low circuitry complexity and with high control accuracy and with a high control dynamic range at the same time, a converter (1) which is supplied from an AC voltage source is connected in series with an active filter on the DC voltage side. The active filter consists of at least one switching cascade amplifier (2A) having a plurality of switching stages (61, 62...67) which can be driven independently of one another and/or of one or more linear amplifier stages. The active filter (2A) injects an AC voltage into the DC voltage circuit of the converter (1), which AC voltage corresponds to the AC voltage which is superimposed on the output DC voltage of the converter (1), but with the opposite mathematical sign. The circuit arrangement can be used advantageously in the case of a power supply for magnets in a particle accelerator.