Abstract: A single stage power factor correction circuit is disclosed. The circuit comprises a first comparator for receiving an output voltage and a reference voltage and for providing a control voltage, a multiplier coupled to the first comparator for receiving the control voltage and an input voltage and then providing a sine wave voltage and a control portion coupled to the multiplier for controlling the sine wave voltage and providing a regulated DC output. Through the use of the circuit in accordance with the present invention, circuit efficiency is increased and the number of circuitry components is reduced. By reducing the number of circuitry components a significant reduction in manufacturing costs is achieved.

Abstract: A multiple output power supply circuit is disclosed. The power supply circuit comprises an input voltage wherein the input voltage is coupled to a driver and a transformer coupled to the input voltage wherein the transformer is coupled to at least one switch. The power supply circuit further comprises at least two rectifiers, each of the at least two rectifiers coupled to the transformer via a winding, each of the at least two rectifiers comprising at least one diode and a controlled switching device coupled in parallel. According to the present invention, the circuit in accordance with the present invention provides multiple power outputs in a substantially more efficient manner.

Abstract: Aspects for a power converter with power factor correction (PFC) circuit are described. The aspects include a buck/boost circuit for achieving a DC voltage from an AC input voltage signal line without developing an inrush current from the AC input voltage line, and a DC/DC converter circuit coupled to the buck/boost circuit for converting the DC voltage to a desired voltage level. The aspects are achieved in a straightforward, cost effective, and adaptable manner.

Abstract: A power supply system is disclosed. The circuit comprises a main power supply portion, the main power supply portion including a transformer, and an auxiliary power supply portion wherein the auxiliary power supply portion is coupled to the main power supply portion via the transformer. Through the use of the power supply system in accordance with the present invention, the auxiliary output voltage is generated by the main power supply. Therefore, the present invention provides the auxiliary output voltage supply by using the same pulse width modulator and switching devices as used by the main power supply. The use of a power supply system in accordance with the present invention thereby eliminates the need for the components required to maintain the auxiliary output voltage.

Abstract: A system and method for maintaining a balanced current level among multiple power supply modules within a parallel power supply. An external voltage is applied to an internal reference translator circuit within each of the parallel power supply modules, such that an internal current-sharing voltage reference is generated within each power supply module. An external reference translator circuit is biased by an independent voltage level, such that the external reference translator circuit generates an external current-sharing voltage reference that is maintained at a higher voltage level than the internal current-sharing voltage references generated within the parallel power supply modules. The external current-sharing voltage reference acts as a master current share reference with respect to which each of the internal current-sharing voltage references.

Abstract: An over-voltage protection circuit for use with a power converter having an output inductor and an isolation diode coupled to an output terminal of the power converter. The over-voltage protection circuit includes a comparison circuit that compares sensed voltages from the anode and cathode nodes of the isolation diode and, in response to the anode having a lower voltage than the cathode, generates a drive signal. The drive signal is received by an active bleed circuit, coupled to the output terminal of the power converter, that provides a current path to keep current flowing through the output inductor to prevent the power converter from going into a discontinuous conduction (DCM) mode of operation.

Abstract: A switching controller for use in a power converter having a controllable switch and operable in a critically continuous conduction mode (CCCM). The switching controller includes an error amplifier that senses an electrical characteristic of the power converter and compares the electrical characteristic to a reference electrical characteristic to generate an error signal. Next, the error signal is provided to a drive signal generator, which is coupled to the controllable switch, that compares the error signal to a reference waveform and provides, in response thereto, a drive signal to the controllable switch. A waveform shaping circuit modifies the reference waveform by comparing a sensed voltage across the controllable switch to an input voltage and provides, in response to the sensed voltage being lower than the input voltage, a modifying signal to the drive signal generator. The modifying signal modifies the reference waveform which also causes the drive signal generator to turn-on the controllable switch.

Abstract: A secondary power supply with a battery charging circuit for use with a primary power supply having an AC power relay coupled to a AC power source and a DC/DC power converter is disclosed. The secondary power supply includes a battery bank having positive and negative terminals, wherein the negative terminal is coupled to a negative power rail of the primary power supply. An auxiliary switch in the AC power relay, having first and second contacts coupled to the positive terminal of the battery bank and a positive power rail of the primary power supply, respectively, is closed in response to a loss of the AC power source. A battery charger circuit, coupled to the auxiliary switch and the battery bank, utilizes a voltage output from the DC/DC power converter to regulate charging of the battery bank. The battery charger circuit, in one embodiment, includes a regulation circuit that senses a plurality of electrical characteristics of the battery bank and, in response thereto, generates a control signal.

Abstract: A system and method for adjusting the maximum allowable current limit for each of a plurality of parallel power supplies within an N+1 power supply system in response to dynamic variations in the total supply current capacity of the N+1 power supply system. A plurality of parallel supplies make up the N+1 power supply which provides power to a load. A sensor within each of the parallel power supplies determines an operating status of each of the parallel power supplies. A detector circuit in communication with the sensors translates the operating status determination into a supply current capacity signal. Finally, a current limit adjustment circuit generates a current limit signal in response to the supply current capacity signal, such that the maximum allowable current limit for each parallel power supply is adjusted while maintaining the overall power supply VA limit for the N+1 power supply.

Abstract: A direct current (DC) power supply supplies at least a first output and a second output having opposite voltage polarities. A protection circuit is coupled to the first and second outputs of the DC power supply, where the protection circuit includes a summing circuit that sums the voltages of the first and second outputs, an over-voltage detection circuit coupled to the summing circuit, and a shutdown latch. In the event of an overload or short circuit fault on one of the outputs of the power supply, the sum of the voltages of the first and second outputs exceeds a threshold voltage, causing the over-voltage detection circuit to output an over-voltage signal. In response to the over-voltage signal, the shutdown latch disables are at least one output of the DC power supply in order to prevent damage to its internal components.

Abstract: A pulse width modulated power supply minimizes overshoot during start up and when one phase of plural phase power supply resumes after dropping out. The power supply comprises an input transformer having a primary winding, a secondary winding and means for coupling one end of the primary winding to a power source. A switch is connected in series with the primary winding to control power through the primary winding. An output capacitor is coupled to receive current from the secondary winding to develop a DC output voltage. A differential amplifier is coupled to receive a reference voltage at a first input and a voltage based on the output voltage at a second input. A feedback capacitor is coupled between an output of the amplifier and the second input to filter out 120 hertz ripple. An output of the differential amplifier is used to control a duty cycle of the switch.

Abstract: A power supply circuit receives and rectifies a three phase power source. A first capacitor is coupled to filter and store the rectified three phases and supply the stored energy to a DC/DC converter. The first capacitor is large enough, when all three phases are present, to filter the rectified input power and supply rated voltage to the DC/DC converter between peaks in the phases, but not too large as to adversely affect the power factor. However, when one phase drops out, additional capacitance is required to maintain rated voltage to the DC/DC converter during the periodic absence of the one phase. Thus, a switch and a second capacitor are connected in series with each other and in parallel with the first capacitor. In response to absence of one of the phases, the switch is activated to couple the second capacitor to filter and store the rectified two phases and supply the stored energy to the DC/DC converter.

Abstract: AC line stabilization circuitry is provided for high power factor loads for protecting bulkless AC/DC converters against lightning or other energy surges while simultaneously providing additional holdover capacity for AC line drop-out conditions. The stabilization circuitry diverts energy surges in the line caused by lightning or other conditions from being applied to the input of the converter by charging a capacitor, and the stabilization circuitry further provides enhanced holdover capacity during AC line drop-out conditions. The stabilization circuitry in accordance with the present invention utilizes simple sensing means operatively associated with a switch coupled to stabilization means for providing a stabilized input voltage to a bulkless AC/DC converter.

Abstract: A pulse width modulated power supply comprises a power transformer having a primary winding, a secondary winding and means for coupling one end of the primary winding to a DC power supply. A semiconductor switch is coupled to the other end of the primary winding to control power through the primary winding. A rectifier is connected across the secondary winding to rectify current induced in the secondary winding, and supplies the rectified current to an output capacitor to develop a DC output voltage. A control circuit controls the duty cycle of the switch based on charging time of a first, relatively small capacitor during start up. The resultant voltage is compared to a reference voltage and when the voltage across the first capacitor just exceeds the reference voltage, the switch is turned off. Because the first capacitor is relatively small, the charging time is short and widths of pulses through the primary winding are relatively short during start up. This reduces heating of the switch during start up.

Abstract: A control for a pulse width modulated power supply controls the duty cycle to provide sufficient charging to the output capacitor to satisfy a rated load, yet avoids saturation of the power transformer and overheating of the switch during and after excess line voltage conditions. The control comprises a sense transformer in series with a power transformer, a DC power source and a modulating switch. A rectifier is connected to a secondary winding of the sense transformer. The control also comprises a first capacitor coupled to the rectifier to receive charging current therefrom. The on time of the switch is based on a comparison of a voltage across the first capacitor to a first reference voltage while the power source exhibits rated conditions. During a large voltage transient the first reference voltage rises to an excess level and maintains the excess level after the transient subsides.

Abstract: In critically continuous boost converters used to achieve high power factor and low input current harmonic distortion, a power FET is driven by a pulse generator whose on time is essentially constant over a single line cycle. Off time is terminated when current in the inductor falls to zero and the voltage on the side of the inductor not connected to the input voltage is less that the input voltage. A delay causes turn on to occur at the minimum of the voltage ring to minimize turn on switching losses. At voltages when the input voltage is less than one half of the output voltage part of the on time, turn on occurs with negative current flowing through the FET power switch and the inductor. Part of the turn on time is used to charge the inductor current back to zero before energy can begin to flow back into the output of the converter.

Abstract: A plurality of AC/DC converters connected in parallel, are provided in which any one of the power converters can fail with-out affecting the operation of the machine which the plurality of converters are providing power. The failed AC/DC converter can be removed and replaced by another converter without shutting down the system. The output voltage of each converter is sensed on the power supply side of a decoupling diode. This allows each one of the converters to operate with its own sense loop and, therefore, the feedback loop does not open when a converter is removed and another used in its place. Each of the parallel connected AC/DC converters is designed to provide a preset maximum power which is independent of AC line voltage variation. To limit the power, the control voltage is made inversely proportional to the average input AC line voltage. The output voltage of the AC/DC converter is made to vary as a function of the load.

Abstract: A self-oscillating power converter utilizes a MOSFET power transistor switch with its output electrode coupled to a tuned network that operatively limits the voltage waveform across the power switch to periodic unipolar pulses. The transistor switch may be operated at a high radio frequency so that its drain to gate interelectrode capacitance is sufficient to comprise the sole oscillatory sustaining feedback path of the converter. A reactive network which is inductive at the operating frequency couples the gate to source electrodes of the transistor switch and includes a variable capacitance as a means of adjusting the overall reactance, and hence the converter's switching frequency in order to provide voltage regulation. A resonant rectifier includes a tuned circuit to shape the voltage waveform across the rectifying diodes as a time inverse of the power switch waveform.

Abstract: An off-line switcher flyback-type power converter circuit is designed having energy and operative control circuits operating off a tertiary winding of the power transformer. A delayed current shutdown circuit permits starting in the face of high demand current loads whereby the load is supplied with bursts of current as start up is cyclic and delayed shutdown is also cyclic in this situation.