Abstract: Two power transistors operating in push-pull, connected in series with respective halves of a transformer primary across a d-c source, are alternately rendered conductive by driving pulses generated during fractions of corresponding half-cycles of a square-wave oscillator. Two integrating networks, connected across these primary halves or across resistors in series therewith, work into a comparator whose output signal, reflecting a dissymmetry between the transistor currents, unbalances the square-wave oscillator to vary the relative width of the two sets of driving pulses until the dissymmetry substantially disappears.

Abstract: Improved start-up circuitry is disclosed for a switching power supply including transformer inverting circuitry that is responsive to a pulse-width-modulated gating signal for providing a DC output voltage from an AC input voltage. The switching power supply further includes comparing circuitry for comparing the DC output voltage to a reference voltage and providing an error signal proportional to the difference therebetween, and control circuitry for pulse-width modulating the gating signal in response to the error signal. After initial AC power turn-on or after subsequent AC power interruptions, the start-up circuitry momentarily enables the control circuitry to pulse-width modulate the gating signal at a maximum duty cycle. The gating signal is otherwise pulse-width modulated at a minimum duty cycle by the control circuitry until the error signal is established.

Abstract: Disclosed is an overcurrent protection apparatus in a switching power supply, including a power switching element for interrupting the primary current of a transformer, and a control circuit for generating control pulses which are modulated in pulse width in accordance with a variation in the rectified output voltage on the secondary side of the transformer, the opening and closing of the power switching element being controlled by the control pulses to maintain the rectified output voltage at a constant value. The overcurrent protection apparatus further includes overcurrent detection means which issues an overcurrent detection signal after detecting that a current flowing into the power switching element has exceeded a prescribed value; memory means set by the overcurrent signal; a gate circuit for blocking the passage of control pulses when the memory means has been set; and reset means for resetting the memory means in response to the trailing edge of a control pulse.

Abstract: A high voltage power supply whose output is regulated even though the line voltage input may vary. The power supply comprises essentially a circuit which receives the line voltage and converts it to a square wave form which is supplied to the primary of a step-up transformer. The output of the step-up transformer is directed to a voltage multiplier and feedback unit. The output of the feedback portion of the unit is compared and controlled so that a constant high voltage output is achieved. The balance of the voltage from the multiplier and feedback unit is used to power a load.

Abstract: A switching regulated push pull converter which includes voltage and current feedback loops to provide a highly regulated output voltage throughout a 100 percent load range. This circuit also provides a semi-regulated auxiliary output voltage which can be loaded beyond 100 percent of its load range with no minimum load requirement on the highly regulated output voltage. A direct current drive circuit for the push-pull power switches provides a transformerless proportional drive and means are provided to compensate for transformer asymmetry.

Abstract: A DC to DC converter is shown having an inductor with primary and secondary windings whose primary winding is serially connected to the center tap of the primary winding of a push-pull transformer. The primary of the transformer is then connected through its ends by a pair of transistor switches to ground while the ends of the secondary of the transformer connect through diodes to an output terminal. The ends of the secondary of the transformer also connect through diodes to the inductor secondary and then to the output terminal. The presence of the inductor prevents the voltage across the switches from becoming twice the input voltage as in conventional circuits. By equalizing the secondary to primary turns ratio between the inductor and transformer, it is possible to equalize the voltage output during the time intervals when the switches are on and off.

Abstract: The unbalance in currents flowing alternately in the two halves of a doubended, push-pull inverter is obviated by means of a parallel resonant network, comprised of an inductor and capacitor, placed in series with the power supply voltage applied to the center tap of the inverter transformer primary winding. The network component values are selected to provide relatively a high impedance of the inverter fundamental operating frequency while providing a low impedance at twice the fundamental operating frequency.

Abstract: A fixed frequency pulse width modulated current fed inverter power supply with imbalance compensation provided by means of a primary inductor in the input circuit. Energy is coupled between the primary inductor in the input and secondary inductor windings in the output circuits to provide a balanced power supply with good efficiency.

Abstract: A switched mode power supply employs a pulse width modulation controlled DC-to-DC converter to change a first voltage from a source of DC power into a regulated power source providing direct current at a second DC voltage. A transformerless current-sensing device is adapted for connection in the path between said source and said converter and provides a control signal which is representative of the current flowing in said path. A current-limiter control circuit is responsive to said control signal and provides an enabling output state when the sensed-current exceeds a predetermined value. The enabling state overrides the pulse width modulator control and inhibits the converter, thus terminating the output pulse when the sensed current exceeds said predetermined value.

Abstract: A switching mode power supply provides a D.C. output voltage having a value related to the duty cycle of the supply's controlled oscillator produced signal. The inventive shutdown circuit inhibits operation of the supply if the duty cycle increases to a value indicative of failure of the supply to produce a minimum desired output voltage. Operation of the supply is inhibited for a predetermined shutdown interval following which a restart cycle deactivates the shutdown circuit for a period to allow the supply to attempt to establish its desired output.

Abstract: DC to DC converter having DC input and DC output, a first switching element to repetitively connect and disconnect the DC input to an inductance winding connected through the first switching element. A source of pulse width modulated signal provides a control signal based on the detected output voltage of the converter. A second detector which detects a variation in the output load. A second switching element which controls the inductance of the winding is actuated based on the second detected signal.

Abstract: A ramp generator has a capacitor connected via a resistor to charge toward 2-volts on the clock lead. The other side of the capacitor is connected to a voltage divider between the control voltage input and ground, to give the initial value of the ramp, which determines the pulse width output. The ramp output is connected to the set input of a D type flip-flop, whose output is the desired pulse width. Another flip-flop is toggled by each clock pulse, to control the alternating selection of two output gates. Three diodes in series from the clock lead to the ramp conductor, across the capacitor, and then to ground are used to reset the ramp when each clock pulse goes to ground potential.

Abstract: A switched DC-to-DC converter in a power supply is powered by input line current from an external power source and driven by voltage pulses from a variable duty cycle pulse width modulator for converting a DC input voltage to a DC supply voltage of a different value that is applied to a load impedance. A comparator monitors the supply voltage for producing an error voltage that biases the modulator for adjusting the width of the voltage pulses, and thus the duty cycle of the converter, for maintaining the supply voltage relatively constant. An RC circuit integrates the voltage pulses for producing an indication of the average value thereof, which is directly related to the value of line current drawn by the converter. When the average value of voltage pulses exceeds a reference voltage, the value of bias voltage is limited for establishing the maximum width of voltage pulses and duty cycle of the converter, and thereby limit the maximum line current drawn by the power supply.

Abstract: An inverter power supply circuit that compensates for variations in the power supply's output voltage, which variations are due to variations in output loading, is disclosed. The input side of the circuit's DC-DC Converter-Inverter-Converter coupling transformer incorporates a compensation network having an impedance that is equivalent to the power supply's output impedance. Variations in the output loading cause corresponding proportional changes in the currents passing through the load and the compensating network. The changing current in the compensating network on the input side of the coupling transformer generates a corresponding changing voltage that is coupled, as a positive feedback, to the chopping transistor of the power supply to provide compensation for the variation in loading on the output side of the coupling transformer.

Abstract: Current spikes in a buck power converter due to commutating diode turn-off time is eliminated by using a tapped inductor in the converter with the tap connected to the switching transistor, without the commutating diode in the usual place, and instead connected to conduct current from one end of the tapped inductor remote from the load during the interval in which the transistor is not conducting. In the case of a converter having a center-tapped (primary and secondary) transformer between two switching power transistors operated in a push-pull mode and two rectifying diodes in the secondary circuit, current spikes due to transformer saturation are also eliminated by using a tapped inductor in the converter with the tap connected to the rectifying diodes and a diode connected to conduct current from one end of the tapped inductor remote from the load during the interval in which the transistors are not conducting.

Abstract: In a duty cycle modulated power regulating apparatus, loss of regulation is anticipated by monitoring the duty cycle of the regulating means.

Abstract: A self-balancing d-c/a-c converter comprises a transformer whose primary winding is split into a pair of symmetrical halves each connected in series with a respective transistor and an associated resistor across a supply of direct current. A differential amplifier, with inputs connected across the two resistors through a pair of low-pass filters, generates an unbalance signal d in the form of a voltage of either polarity which is additively and subtractively superimposed upon a reference voltage e to provide two control signals e+d and e-d fed to respective inputs of two comparators. Two synchronized signal generators produce a sawtooth oscillation a and a square wave f, the latter having a period which is twice that of the former. Sawtooth wave a is fed in parallel to the other inputs of the two comparators while the square wave f and its complement g alternately unblock a pair of AND gates in cascade with these comparators.

Abstract: A switching regulator includes a DC voltage source having a pair of DC output terminals, a switching transformer having first and second primary windings connected in series, a magnetic core and a secondary winding, a first switching transistor connected in series between the pair of DC output terminals through the first primary winding, a second switching transistor connected in series between the pair of DC output terminals through the first and second primary windings, a rectifier circuit connected across the secondary winding. A pulse width modulator is provided to produce a PWM (pulse width modulated) control signal the duty of which is proportional to the voltage of the rectifier circuit and the PWM control signal is selectively supplied to one of the first and second switching transistors in accordance with the low or high circumstance of the load.

Abstract: A regulated power supply system is disclosed including a source of unidirectional electric current, and at least one switch device including a saturable reactor controlled between a saturated condition and an unsaturated condition in a duty cycle such that the load voltage tends to remain constant with varying load current. In one embodiment, a pair of switch devices are coupled, respectively, between the ends of a center-tapped secondary winding of a transformer having a primary winding fed from an inverter, and a pair of rectifier devices coupled to provide the unidirectional current to the load. Control of the switch devices is effected by applying an appropriately varying control voltage to like electrodes of respective inverted control diodes each coupled to the junction between a respective switch device and its associated rectifier device. The control diodes are driven from the output of a comparator amplifier responsive to the difference between the load voltage and a reference voltage.

Abstract: A switching regulator includes a chopper circuit and a DC-DC converter. A switching signal for use with the chopper circuit is derived from an inverter portion of the DC-DC converter so as not to use an external pulse oscillator. A DC voltage feedback circuit is provided from the output of the DC-DC converter to the chopper circuit so as to stabilize the DC output signal of the DC-DC converter. Alternatively, the DC voltage feedback is provided from an output of the chopper circuit.

Abstract: An inverter drive circuit is disclosed wherein the inverter is a pulse width modulated inverter. The inverter includes a regulator circuit to regulate the width of the pulses which control the conduction of first and second controllable semiconductors in the inverter. The regulator is controlled by the output of the inverter in a feedback arrangement with a current limit circuit as well as an instant current limit to limit the output. A turn-on circuit is utilized to act through a drive transformer to turn on the controllable semiconductors as required. A turn-off circuit acts on the drive transformer and turns off the turn-on signal. A set and reset circuit is provided using first and second drive transformers for first and second controllable semiconductors in the inverter. One transformer is set in order to provide the turn-on and then this transformer is energized in the opposite direction to saturation to obtain a reset.

Abstract: An essentially non-dissipative, strap-free, continuously adjustable power unit inherently impervious to shorts and open circuits for powering repeaters in a T1 or similar telephone span line is disclosed. The unit uses a pulse-width modulated inverter in the converter input circuit to produce a variable-voltage D.C. output to the span line. The pulse width or duty cycle of the inverter is controlled by a control logic which senses the span line current and maintains it at a selectable predetermined level without any apreciable power dissipation.

Abstract: A power supply arrangement that substantially eliminates the effects of the sidebands and harmonics at the switching frequency of the power supply on the RF carrier of an amplifier or other unit being supplied power. The switching frequency of the power supply arrangement is continuously varied in frequency at an appropriate rate and deviation with the result that a band of frequencies replaces the fundamental switching frequency of the power supply and all harmonics so that noise created by the switching frequency signal and the RF signal are then similarly diffused. The net power present as spurious noise in the amplifier unit is constant with the maximum amplitude of the noise as viewed, for example, in a doppler filter being substantially reduced. In a radar transmitter, for example, the transmitted pulse frequency appears as PRF sidebands of the CW frequency and the extraneous modulation from the switched power supply provides sidebands of the PRF sidebands.

Abstract: A pulse width modulated DC-to-DC converter circuit is disclosed having a el means for permitting each of the switching transistor duty cycles to exceed 50% without the occurrence of current spikes at the input winding of the output transformer. These current spikes result when both switching transistors are on when each of the transistors switch operating states at an instantaneous point in time. As a result, a wide range of input power source voltages can be utilized for a given output voltage thereby resulting in a wide range of voltage regulation. This result is achieved by utilization of an energy storage choke between the battery means and the input winding of the output transformer. Whenever there exists an instantaneous current spike, the choke absorbs the spike.

Abstract: An improved series inductor/parallel inverter power stage and power staging ethod for a transistor controlled DC-DC power converter in which the integrating capacitance is located in the output of the power stage transformer and the series inductor has a secondary winding connected across this capacitance for transferring stored energy from the inductor primary directly to the transformer output rather than through the transformer, and current flow through the transformer primary is controlled by two parallel, alternately conducting pulse-width-modulated transistors in a manner such that only a single transistor is located in the main current flow path at any given time. The improved power stage is characterized by reduced power dissipation and peak voltage stresses on the transistors, increased simplicity, and improved reliability.

Abstract: A pulse width modulation (PWM) converter circuit for transforming a first DC voltage into a secondvoltage (AC or DC), wherein the magnitude of the second voltage is regulated by the converter circuit. The converter circuit comprises a clock circuit, a master pulse width modulator (PWM) circuit and n slave pulse width modulator (PWM) circuits. The clock circuit provides a symmetrical train of rectangular pulses on each of n+1 conductors, wherein only one pulse occurs on any one of the conductors at one time. The master PWM means is responsive both to the train of pulses on one of the n+1 conductors and to a feedback signal indicative of the magnitude of the second voltage; the master PWM means controls the flow of current, due to the first DC voltage, through a portion of a transformer primary winding.

Abstract: A digitally regulated power supply for the corona charging unit of an electrostatic copying machine in which a sample of the ionic current of the corona unit is utilized in conjunction with a digital regulator to regulate the power supply establishing the charge of the corona. The digital regulator in conjunction with at least one pulse width modulated power supply permits very fast rise and fall times of the power supply current. Further, between duty cycles of the machine, the digital regulator stores a representation of the correct operating point of the corona charging unit determined in the immediately prior duty cycle. In the next duty cycle, the representation is utilized by the digital regulator to initially regulate the power supply.

Abstract: A regulated DC to DC power supply which minimizes input bus current changes caused by low frequency cyclical load variations is disclosed. The power supply includes a regulator connected to the input bus and controlled by a pulse width modulator. The regulator converts the DC voltage on the input bus to a higher, regulated DC voltage which is supplied to a variable load. A voltage feedback circuit is connected to the output of the boost converter and generates a control voltage which is supplied to the pulse width modulator to regulate the output voltage for variations in line voltage and load. The voltage feedback circuit includes an operational amplifier having a reference voltage supplied to a positive input terminal, and the output of the regulator supplied to a negative input terminal. A frequency response shaping network is connected between the output and the negative input terminal of the operational amplifier.

Abstract: A current balance arrangement for the power switching devices of a push-pull converter circuit is disclosed. A dynamic dead band circuit is incorporated into a pulse width modulation current balance and output voltage regulation control circuit to prevent current imbalance from causing saturation of the power transformer core for all operating conditions of the converter including input voltage falling below its rated low-line value, sudden load surges, or turning off of the converter power supply. Whenever the dynamic dead band circuit determines that inverter current flow is being terminated by the dead band interval of the converter clock, a control signal is sent to the pulse width modulation circuitry of the converter to effect inverter current termination prior to initiation of the clock dead band interval in subsequent cycles of converter operation. The invention eliminates the need for providing inverter power switching devices having closely matched electrical characteristics.

Abstract: A DC to DC converter is disclosed wherein the output voltage is regulated by the control of current pulses in an inverter stage. The converter output voltage and a defined reference voltage are compared to generate error signals and current flow in the inverter stage is monitored to generate proportional current signals. The error signals are directly compared to the current signals by a comparing circuit which comprises a voltage ampliflier and a current source. The error signals are coupled to the voltage amplifier which maintains a corresponding voltage on one side of a resistor. The current signals are coupled to the current source which is connected to the other side of the resistor and maintains the current flow through the resistor at a level equal to the current signals.

Abstract: A DC to DC converter has an unregulated input and provides a pair of regulated outputs which independently provide variable power on demand to two independent loads at a substantially constant output voltage. The converter includes three major sections, the input oscillator and pulse width modulation section, the isolated negative DC regulator and the isolated positive DC regulator. Each of the DC regulators is current limited and each is provided with overvoltage protection. One of the output regulators provides improved efficiency through the use of a pair of appropriately connected catch diodes which decrease current change through a filtering inductor, and through implementation of a combined regulator preload resistor and AC pulse width modulating switching transistor drive current source. The converter is a compact modular unit having a low profile with circuit components arranged to minimize temperature instability.

Abstract: A D-C converter obtains high voltage by peak-to-peak rectification of alternating potentials supplied at the secondary of a step-up transformer. The primary winding of the transformer is tuned with series capacitance and driven from the output circuit of a pulse amplifier providing pulses with a repetition rate equal to, or an integral submultiple of, the resonant frequency of the tuned transformer primary. The pulse amplifier is made to offer a low source-impedance so that the Q of the tuned primary is large enough that a substantially sinusoidal voltage with peak-to-peak value several times as large as the amplitude of the pulses supplied by the pulse amplifier appears across the primary. This desirably permits the step-up ratio of the transformer to be reduced.

Abstract: A switching regulator includes a chopper circuit and a DC-DC converter. A switching signal for use with the chopper circuit is derived from an inverter portion of the DC-DC converter so as not to use an external pulse oscillator. A DC voltage feeback circuit is provided from the output of the DC-DC converter to the chopper circuit so as to stabilize the DC output signal of the DC-DC converter.

Abstract: A direct current voltage power supply in which spaced pulses of current are made to flow through the primary winding of a power transformer. The anode-cathode path of an SCR device is connected from a point on a secondary winding to an output capacitor. A pulse width modulation circuit and a base drive circuit are connected between the output capacitor and the gate electrode of the SCR device so as to apply a pulse to the gate electrode that enables conduction between the source and drain electrodes whenever the voltage across the output capacitor drops below a given reference value.