Abstract: Circuit and apparatus for improving operating features characteristics of DC power supplies implementing three Phase transformer devices of the type such as 12-step and 24-step transformers. The circuit and apparatus reduces harmonic AC input current while providing almost unity power factor for DC power supply outputs intended for aircraft or marine applications where size and weight are concerns. The circuit includes a passive series connected nonlinear resonant LC circuit connected at each phase of the input to the three phase transformer With the three phase transformer having the added series nonlinear resonant LC circuit, the power supply is enhanced with current limiting for the entire transformer, rectifier and load, due to load shorting, input voltage transients, transformer winding short circuit or rectifier failure. Further, such apparatus provides limiting of power inrush currents during voltage application or turn on, while also providing EMI filtering.

Abstract: Apparatus and method for providing closed loop feedback control for switch-mode DC/DC power converter with multiple outputs using digital filter feedback, in contrast to analog error feedback. In the apparatus and method, multiple outputs for a switch-mode DC/DC power converter are regulated by digital means, including the allocating or partitioning of digital control resources among each of the multiple outputs. The partitioning of control resources may be in response to operating conditions.

Abstract: A harmonic input current reduction and power factor correction circuit for three phase, power supplies. The circuit includes passive elements including a series inductance and capacitor connected between each AC line of a three phase voltage source, and each input phase of the uncorrected power supply. The inductance and capacitor are designed and chosen to meet linearity and volt ampere requirements to achieve total harmonic current levels of less than 10%, and power factors greater than 0.98. This is achieved with less than 1% loss in line operating input voltage range and overall efficiency of greater than 99.5%. Further, the dynamic response of a circuit to power supply load transient demands is limited in voltage overshoot or undershoot effects.

Abstract: A harmonic input current reduction and power factor correction circuit for three phase, power supplies. The circuit includes passive elements including a series inductance and capacitor connected between each AC line of a three phase voltage source, and each input phase of the uncorrected power supply. The inductance and capacitor are designed and chosen to meet linearity and volt ampere requirements to achieve total harmonic current levels of less than 10%, and power factors greater than 0.98. This is achieved with less than 1% loss in line operating input voltage range and overall efficiency of greater than 99.5%. Further, the dynamic response of a circuit to power supply load transient demands is limited in voltage overshoot or undershoot effects.

Abstract: An AC-DC power supply circuit utilizing an output stage configuration designed to achieve no output ripple at the power line frequency. To eliminate the ripple formed, each separate processing output stage corresponding to a respective ac voltage source phase which provides a 120 Hz ripple, is stacked, in a series connection, and due to their respective ripple phase shifts of 120° degrees, achieves ripple cancellation at the output.

Abstract: An AC-DC power supply circuit utilizing an output stage configuration designed to achieve no output ripple at the power line frequency. To eliminate the ripple formed, each separate processing output stage corresponding to a respective ac voltage source phase which provides a 120 Hz ripple, is stacked, in a series connection, and due to their respective ripple phase shifts of 120° degrees, achieves ripple cancellation at the output.

Abstract: An alternate approach to meeting the harmonic current limits specified in EN61000-3-2 for power supplies, which fall under the classification of Class A equipment and also provide universal input voltages. In use, an electronic switch(triac) is used as the simple switch between low line input(90-132 VAC) and high line input(180-254 VAC) to provide an auto ranging front end. An inductor is placed in series with the input bridge diodes to increase the conduction angle of the input line current, thereby, increasing the power factor of the supply. This inductor is switched in series with the bulk capacitor whenever the triac is off. In this way, the harmonics are reduced at high line only, and the supply runs unaffected with low power factor at low line. Thus the harmonic currents are reduced at the test voltage of 230V without the need for an active power factor corrective front end.

Abstract: An alternate approach to meeting the harmonic current limits specified in EN61000-3-2 for power supplies, which fall under the classification of Class A equipment and also provide universal input voltages. In use, an electronic switch(triac) is used as the simple switch between low line input(90-132 VAC) and high line input(180-254 VAC) to provide an auto ranging front end. An inductor is placed in series with the input bridge diodes to increase the conduction angle of the input line current, thereby, increasing the power factor of the supply. This inductor is switched in series with the bulk capacitor whenever the triac is off. In this way, the harmonics are reduced at high line only, and the supply runs unaffected with low power factor at low line. Thus the harmonic currents are reduced at the test voltage of 230V without the need for an active power factor corrective front end.