Showing papers on "Switched-mode power supply published in 1985"

Topics in multiple-loop regulators and current-mode programming

Abstract: Some general considerations about multiple-loop feedback are discussed, and it is concluded that incorporation of a current-programmed power stage into a “new” power stage model is both justified and useful. A new circuit-oriented model of the current feedback path is derived which augments the well-known power stage canonical circuit model.

A Systematic and Unified Approach to Modeling Switches in Switch-Mode Power Supplies

Abstract: This paper describes a new, systematic, and unified approach to model the low-frequency behavior of power switches in Switch-Mode Power Supplies (SMPS). This approach starts with a simplification of the switching converter circuit to a Minimum Separable Switching Configuration (MISSCO) containing all power switches but a minimum number of other components, before analysis on the MISSCO is carried out. Then by making use of an impulse-response method and averaging technique, a set of equations describing the low-frequency behavior of the MISSCO are derived. The resultant equations can be used to generate a low-frequency equivalent circuit of the MISSCO, which can then be combined with the rest of the SMPS circuit to form a complete equivalent circuit.

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

Power source device for a load with a stand-by power supply system

Abstract: A power source device according to this invention comprises a voltage and phase detector for detecting the voltage and phase of a power supply system, a first controller for controlling an inverter so that an output of the inverter may agree with either a reference voltage and a reference phase or with the voltage and the phase of the power supply system, a second controller for switching the inputs of the first controller from the reference voltage and phase to the power supply system voltage and phase, or vice versa, when the phases of a reference oscillator and the power supply system have agreed, and a third controller for switching the power to a load from the inverter to the power supply system, or vice versa, when the synchronism between the inverter output and the power supply system has been detected.

Buck boost switching regulator with duty cycle limiting

Abstract: In a buck-boost, switching regulator, separate signals are developed to control duty cycles of regulator switches. Control exercised by a pair of feedback-determined reference signal voltages through which a ramp signal is swept at inputs of separate comparators, comparator outputs control respective switches. A predetermined maximum voltage difference is permitted between the reference signal voltages. The reference used to control switching of one end of the regulator inductance is limited to a minimum voltage corresponding to a minimum duty cycle greater than 0% while the other reference is used to control the other end of that inductance and is limited to a maximum voltage corresponding to a minimum duty cycle less than 100%. A current limiting feedback from one of the switches is operated in response to current in excess of a predetermined level to force the ramp signal to a level corresponding to 0% duty cycle for both switches at the same time.

High switching frequency converter auxiliary magnetic winding and snubber circuit

Abstract: An integrated magnetic assembly for use in the direct current output circuit of a high frequency electronic switching power supply, comprising magnetic core sections for the output transformer and inductor windings and a common magnetic core segment completing the magnetic flux paths for the transformer and inductor windings An auxiliary winding on one or both of the core sections is supplied with energy from the capacitor of a snubber circuit connected across the primary side of the magnetic output circuit This auxiliary winding is magnetically coupled to the secondary side of the magnetic circuit to transfer energy to the power supply output during a portion of the switched current cycle

A low voltage power source power inverter for an electroluminescent device

Abstract: A power inverter for an electroluminescent device is disclosed which enables the electroluminescent device to be powered from a low voltage DC power source. Switching transistors convert the low voltage DC power to low voltage AC power which is subsequently increased and coupled to a resonant circuit including the electroluminescent device. Current in the resonant circuit is sampled, referenced to half the low voltage DC power, and coupled back in phase to an amplifier and switching transistors to create an oscillator which oscillates at a frequency determined by the resonant circuit.

Power supply system and a control method thereof

Abstract: A power supply system including an inverter, a reserved power source and changeover switches for outputting one of outputs of the inverter and reserved power source to supply a load current to a load. The system further includes a control circuit for controlling a phase, a frequency and a voltage of the output of the inverter to coincide with a phase, a frequency of the output of the reserved power source and a specified voltage, respectively. The specified voltage is determined to be a predetermined reference voltage when the load current is below a detection level and to be a reduction voltage decided between zero volt and the voltage of the reserved power source when the load current is equal to or more than the detection level. A method for controlling a power supply system described above is also disclosed.

Soft-start capacitor discharge circuit

Abstract: In a switched mode power supply during start-up, an increasing charge on a soft-start capacitor controls a pulse width modulator for increasing the length of drive pulses provided to a pair of switching transistors until a reference voltage level is reached, after which stable power supply operation ensues. Detection circuitry senses a low power supply output voltage such as arising from input line interruptions and rapidly discharges the soft-start capacitor and prevents the recurrence of the soft-start mode of operation before the soft-start capacitor is fully discharged to prevent overloading of power supply output semiconductor devices upon the resumption of normal input voltage to the power supply.

Memory device having backup power supply

Abstract: A memory device includes a reset signal generator for generating a reset signal when the output voltage from a main power supply circuit to supply a driving voltage to a memory decreases to a first predetermined voltage, and a switching circuit for allowing a data holding voltage from a backup power supply to be supplied to the memory in place of the driving voltage from the main power supply circuit in response to the reset signal. This memory device further includes a comparator for generating an inhibiting signal when it detects that the data holding voltage from the backup power supply following generation of the reset signal is lower than the voltage necessary to hold the data in the memory, and a control circuit for setting the memory into an operation inhibition state when it detects that the inhibiting signal was generated from the comparator following the reset signal.

Reserve power source with power failure detection apparatus

Abstract: A reserve power source, switchably connected to a network between a primary power supply and a load, provides an auxiliary power signal to the load when a power failure condition is detected in the signal from the primary power supply. The reserve power source includes a circuit for instantaneously detecting and switching upon the occurrence of a power outage. An overvoltage/noise detector circuit is included to detect when either a sustained overvoltage condition or a high, short duration overvoltage condition occurs. A low voltage detector circuit is included for detecting a low voltage, or brown-out, condition. When an overvoltage or low voltage condition is detected, a preferred embodiment of the invention switches the load to the auxiliary power signal within one-half cycle of, but in zero-crossing synchronization with, the primary power signal.

Study of a resonant converter using power transistors in a 25KW x-rays tube power supply

Abstract: This paper describes a converter whose purpose is to feed an χ-rays tube (25 KW, 140 KV) from the industrial main power supply (380 V, 50 Hz). The authors justify the structure of this generator that is constituted by an inverter using power transistors and a transformer-voltage multiplier set which are connected by a series resonant circuit. The control logic of the transistors gives them the dual properties of these of thyristors. An accurate analytical study of this system allows to predetermine the characteristics of this converter now in its industrialization phase.

Computer-attached uninterruptable DC power supply

Abstract: A DC power supply comprising a sealed lead-acid battery, a charging regulator, a discharge pass element, an output power switch for disconnected the power supply from the computer and four light-emitting diode indicators which display the condition and trend of the battery charge state. The power supply may be permanently attached to an Apple IIc brand computer without marring the computer's plastic housing by means of tabs on upper and lower projections of the power supply housing which interlock with slots on the upper and lower surfaces of the computer's housing. The power supply also features an electronic "sleep" switch which not only prevents battery drain when the power output switch is turned off, but also prevents deep discharge of the battery and possible damage to the powered equipment when battery voltage drops below a preset value while the output switch is turned on and adequate voltage from the power line is unavailable. The sleep switch disables all of the power supply's circuitry save an input-deactivated driver transistor and a CMOS logic circuit required for both disabling and reawakening the circuitry. A one-shot awakening feature is triggered for approximately one second whenever the output power switch is closed. If the battery is adequately charged, the power supply remains awake; if not, it reverts to sleep. When connected to an adequate DC source, the unit functions as an on-line uninterruptible power supply; when disconnected, the computer becomes a battery-powered portable.

Battery-powered radio communication apparatus capable of prolonging the communicable state thereof

Abstract: A battery-powered radio communication apparatus is disclosed which comprises a power amplifier and a power detector for detecting the output power of the power amplifier. A supply voltage detector compares a standard voltage with the output voltage of a battery supplying power to the power amplifier. A gain control circuit controls the gain of the power amplifier in response to the output of the power amplifier and to the output of the supply voltage detector so as to prolong, by a certain time, the communicable state of the apparatus prior to battery depletion.

Power supply employing low power and high power series resonant converters

Abstract: A power supply is provided for supplying regulated power to an output from an unregulated DC voltage source. The supply includes low and high power series resonant converters, each including a pair of power switches which are alternately turned on and off for completing a series resonant circuit with the source and with a primary winding of a transformer coupled to the output. A switch control responds to loading of the output and drives the switches on and off at an operating frequency that varies with the loading. A converter control monitors the operating frequency and controls operation of the converters such that one or both converters operate in dependence upon loading to avoid operation within a particular frequency range.

The design of a high efficiency, low voltage power supply using MOSFET synchronous rectification and current mode control

Abstract: The power supply described in this paper was developed for use in systems utilizing VHSIC integrated circuits which require voltages between two and three volts at substantial levels of current. The philosophy guiding this design, the pertinent trade-offs which were examined, and the data taken are presented.

Inductive transmission of power and data

Abstract: The application relates to the inductive transmission of power and data, in which a supply voltage after rectification (1) is transmitted via an inverter (2) and a transformer (U) for supporting a battery (8) and switching signals in both directions. This transmission device is preferably intended for pipelines composed of pipe sections. For further simplification of known transmission devices each pipe head is designed as a transformer into which a coil (26) is sunk, and the pipe (21) serves as the transformer core. The transmitted alternating voltage is rectified in a power supply unit (5, 6) on the secondary side of the transformer and is converted to the battery voltage.

Power supply with power factor correction

Abstract: A power supply circuit for feeding a load (1,2), such as one or more fluorescent lamps, from an alternating current source (5) comprises a first bridge rectifier circuit (4) for connection to the a.c. source to provide a unidirectional current supply, and a half-bridge inverter (3) which passes a cylically-reversing current through a load supply circuit (17,19) from the unidirectional supply. For power factor correction, the primary winding (18) of a voltage transformer (19) is connected in the load supply circuit, and the secondary winding (92) of the transformer is coupled to a second bridge rectifier circuit (80) which is connected in series between the first bridge rectifier circuit and the unidirectional supply. Magntic amplifier means (82,83) is connected in series with the secondary winding of the voltage transformer. A current transformer (90) monitors the current flowing from the source, and the monitored current is compared with the current in the load supply circuit. An error signal is derived from the comparison to control the level of magnetisation of the magnetic amplifier means, so that the secondary winding of the voltage transformer extracts current from the a.c. supply, in dependence upon the error signal, to improve the form factor of the current taken from the source. A saturable transformer (17) feeds the lamps, and the level of magnetisation of the transformer can be varied by adjustment of a variable resistance network (71,72), so that the brightness of the lamps can be varied.

Bipolar transistor RF power amplifier

Abstract: A bipolar transistor R.F. power amplifier in which feedback is used to control simultaneously amplitude and phase distortion. The bipolar transistor R.F. power amplifier is operated by determining a set of collector supply voltages located at the onset of gain saturation in the bipolar transistor and using feedback to adjust the collector supply voltage in response to variation in input drive level to operate the bipolar transistor in a mode where gain, phase shift and input impedance are simultaneously linearised, found at the onset of gain saturation. A circuit for determining the selection of collector supply voltages comprises oppositely polarised diode detectors (36, 38) which are connected to the input and output circuits of the amplifier (24). Outputs of the diode detectors (36,38) are applied to a differential amplifier (44) which controls a modulated power supply unit (46) for varying the collector voltage. Preferably the power supply unit is a switched mode power supply unit.

Semiconductor device having an arrangement for preventing operational errors

Abstract: This invention relates to a semiconductor device formed on a semiconductor chip which is provided with at least a voltage transformation arrangement for transforming an external power supply voltage into an internal power supply voltage. At least a portion of circuits formed in the chip operate by using the internal power supply voltage rather than the external power supply voltage. Semiconductor devices, in particular DRAMs (dynamic random access memories), in which said internal power supply voltage is supplied are controlled so that the starting time of the internal power supply voltage at the moment of the switch-on of the external power supply is later than the starting time of the external power supply voltage, and/or the time necessary for the internal power supply voltage to increase to a predetermined operational level at said moment is longer than that required for said external power supply voltage to increase to a predetermined operational level.

Power supply having dual ramp control circuit

Abstract: A power supply (100) includes a first lead (12) for receiving an input voltage (Vin) and an inductor (L1) and a switching transistor (Q1) coupled in series between the input lead and ground. The node (N1) between the inductor (L1) and switching transistor (Q1) is coupled through a diode (D1) to an output terminal (14). When the switching transistor is on current flow causes energy to be stored in the inductor. When the switching transistor turns off, the energy stored in the inductor is provided to a load (RL) coupled to the output terminal. The on-time of the transistor is controlled by a comparator (20) which receives a first voltage (V3) proportional to the current through the switching transistor and a second voltage (V4). The second voltage decreases linearly with respect to time at a rate dependent on the difference between the voltage at the output terminal (Vout) and a reference voltage (Vref). Because of this, the power supply is insensitive to voltage spikes which may appear on the first input lead of the comparator.

Dual operating mode switching power supply

Abstract: A power supply circuit of switching regulator type includes a converter transformer defined by a first winding for receiving input power from a DC source and second winding for producing output power, a switching transistor for alternately making and breaking electric connection between the DC source and the first winding by alternate turn on and off operations of the switching transistor, and a rectifying circuit connected to the second winding for rectifying the output power. A power supply circuit further includes a first error detector for detecting a drift in the rectified output DC current and for producing a first control signal, a second error detector for detecting a drift in the rectified output DC voltage and for producing a second control signal, and a controller for controlling the on and off operations of the switching transistor based on either one of the first control signal and the second control signal so as to stabilize the rectified output power.

Current surge limited power supply

Abstract: An inrush current limited power supply includes a regulator with a capacitor coupled across its input terminals. If voltage to be regulated is suddenly applied by a switch to the input terminals of the regulator, an undesirably large current surge occurs as the capacitor charges. The magnitude of the current surge is limited by a surge limiting resistor coupled in series with the switch. This limits the surge current, but undesirably causes power dissipation in the resistor during normal operation. The channel of a FET is connected across the resistor. The FET has a conductivity which is low when the gate-to-source voltage is low, for preventing large inrush current immediately after turn-on. A control voltage generator generates a control voltage by rectifying an alternating voltage, and it is coupled to the gate and source of the FET. In one embodiment, the control voltage generator is referenced to an input terminal of the regulator. In another embodiment it is referenced to output terminal. The alternating voltage may be generated by an oscillator, or it may be derived from operation of a switching regulator.

A 600 watt four stage phase-shifted-parallel DC-to-DC converter

Abstract: This paper introduces an unconventional SMPS power stage architecture which is developed as four 150w buck-boost or flyback type switching stages which are operated in phase-shifted-parallel (PSP). The flybacks are operated in the continuous mode with intersecting conduction on both input and output sides; they are switched in cyclic sequence with one-fourth of a switching period following turn-on of one stage before turn-on of the next stage. PSP operation provides substantial improvements in intermediate power level SMPS for spacecraft applications.

Pulse position modulated regulation for power supplies

Abstract: A power supply regulator in which a control pulse is generated at a position in time which varies in accordance with the voltage or current supplied by the power supply. The control pulse can be fed back across an isolation boundary with a simple device such as a pulse transformer with little or no loss of accuracy. Such a control signal is particularly adaptable to varying the duty cycles of transistor switch drive signals for switched-mode power supplies.

Power on/off reset generator

Abstract: A power on/off reset generator (5) for monitoring a power supply (10) for a logic system powered from the monitored power supply. A precision-voltage sensor (20) produces a control signal for a time delay circuit (30) when the power supply rises above a preselected threshold voltage (E T ). A delay signal is generated which maintains an active-LOW control signal to the logic system and causes a Schmitt trigger circuit (40) to produce a HIGH control signal to the logic system at the end of the delay signal.

Control circuit for diode-or connected power supplies

Abstract: A control circuit which monitors the output voltage of multiple power supplies connected to each other in a diode-or arrangement. When one power supply provides a higher voltage than the others the control circuit causes the lower output power supplies to operate in a standby mode. The control circuit includes voltage dividers on both sides of the output diode of the power supplies. These voltage dividers provide indications of the voltage output of their associated power supply and the other power supplies. A voltage comparator monitors the output voltage of its associated power supply and the other diode-or connected power supplies as indicated by the voltage dividers. The voltage comparator to adjust the voltage output of the associated power supply to a level just below the high output power supply, thereby leaving it in a standby mode of operation. If the high output power supply provides a reduced level of output voltage the voltage comparator in the standby power supply causes that power supply to then supply power to the load without any interruption in supply of the power.

Shutdown circuit for blocking oscillator power supply

Abstract: A protective circuit arrangement is provided for shutting down a power supply at the occurrence of a fault condition. The circuit arrangement allows current limiting in a switching transistor during a power on and/or power off cycle, but shuts down the power supply if current limiting occurs at any other time.