Abstract: A cost effective solution for power factor correction in power devices operating at two widely separated input voltages comprises two unequal power rails. One power rail is optimized for operation at high line voltage only, while the other power rail is designed only for low line voltage. When operating at high line voltage, the second rail is disabled. At low line, both power rails are enabled but by virtue of unequal boost inductors, the high line power rail handles only about 30% of the power while the low line power rail handles the remaining power. Hence, the efficiency at high line voltage is maximized. As the inductance used in the high line power rail is much higher in value, it stays in continuous conduction mode for all load conditions and hence the power factor is significantly improved.

Abstract: A driver circuit for one or more LEDs includes a power circuit having an output terminal, a capacitor coupled to the output terminal and a switch, and a control circuit coupled to the power circuit for controlling the power circuit. The control circuit is configured to operate the switch for coupling a resistance in series with the capacitor in response to detecting an open circuit condition at the output terminal. Additionally, or alternatively, the driver circuit may include a switched mode power supply, and the control circuit may be configured to switch operation of the switched mode power supply from a current control mode to a voltage control mode, and reduce a current setting for the current control mode, in response to detecting an open circuit condition at the output terminal.

Abstract: A power system includes a plurality of DC/DC converters and a DC/AC inverter. The plurality of DC/DC converters having outputs electrically connected in parallel for supplying a DC voltage bus to an input of the DC/AC inverter. The plurality of DC/DC converters each include a maximum power point tracker (MPPT). Various DC/DC converters and DC/AC inverters suitable for use in this system and others are also disclosed.

Abstract: A power system includes a plurality of DC/DC converters and a DC/AC inverter. The plurality of DC/DC converters having outputs electrically connected in parallel for supplying a DC voltage bus to an input of the DC/AC inverter. The plurality of DC/DC converters each include a maximum power point tracker (MPPT). Various DC/DC converters and DC/AC inverters suitable for use in this system and others are also disclosed.

Abstract: A method of operating a switching power converter having at least one power switch controlled by a drive signal having a switching frequency is disclosed. The method includes monitoring an output power of the switching power converter, determining whether the output power has decreased below a threshold level and, in response to the output power decreasing below the threshold level, changing the switching frequency of the drive signal from a first switching frequency to a second switching frequency when an operating condition of the switching power converter is satisfied. Also disclosed are controllers and switching power converters (including PFC converters).

Abstract: A method of generating an output voltage from a variable input voltage with a power factor correction (PFC) system is disclosed. The PFC system includes a first power rail and a second power rail connected in parallel between an input for receiving the input voltage and an output for outputting the output voltage. The method includes operating one or both of the first power rail and the second power rail to generate the output based, at least in part, on whether the input voltage exceeds a threshold voltage. Power supplies and PFC systems suitable for performing the method are also disclosed.

Abstract: A method of controlling a power converter having at least one switching device for supplying an output voltage and a load current to a load is disclosed. The method includes sensing the output voltage and sensing the load current. The method further includes controlling a duty cycle of the switching device according to the sensed output voltage and a voltage control loop when a rate of change of the load current does not exceed a threshold level. The method also includes adjusting the duty cycle of the switching device set by the voltage control loop when the rate of change of the load current exceeds the threshold level.

Abstract: Methods of regulating an output voltage of a multi-output isolated power converter are disclosed. One method includes allowing the output voltage to vary unregulated when the output voltage is below a threshold value and preventing the output voltage from increasing when the output voltage reaches the threshold value. Additional methods and multi-output power supplies are also disclosed.

Abstract: A power conversion system for use with a photovoltaic (PV) power source may include a DC/DC converter for converting a first DC voltage into a second DC voltage, an isolation transformer, an inverter for converting DC power to AC power, and at least one controller for controlling the DC/DC converter and the inverter. The controller may be configured to operate the DC/DC converter as a buck converter or a boost converter based, at least in part, on whether the first DC voltage is less or greater than a reference voltage. Additionally, the controller may operate the converter according to a maximum power point tracking algorithm. Further, the controller may be configured to operate the inverter to control the DC voltage at the inverter's input as a function of the AC voltage at the inverter's output. Example embodiments of power systems, DC/DC converters, DC/AC inverters and related methods are also disclosed.

Abstract: A power system includes a plurality of DC/DC converters and a DC/AC inverter. The plurality of DC/DC converters having outputs electrically connected in parallel for supplying a DC voltage bus to an input of the DC/AC inverter. The plurality of DC/DC converters each include a maximum power point tracker (MPPT). Various DC/DC converters and DC/AC inverters suitable for use in this system and others are also disclosed.

Abstract: A power system includes a plurality of DC/DC converters and a DC/AC inverter. The plurality of DC/DC converters having outputs electrically connected in parallel for supplying a DC voltage bus to an input of the DC/AC inverter. The plurality of DC/DC converters each include a maximum power point tracker (MPPT). Various DC/DC converters and DC/AC inverters suitable for use in this system and others are also disclosed.

Abstract: Methods of regulating an output voltage of a multi-output isolated power converter are disclosed. One method includes allowing the output voltage to vary unregulated when the output voltage is below a threshold value and preventing the output voltage from increasing when the output voltage reaches the threshold value. Additional methods and multi-output power supplies are also disclosed.

Abstract: Methods of regulating an output voltage of a multi-output isolated power converter are disclosed. One method includes allowing the output voltage to vary unregulated when the output voltage is below a threshold value and preventing the output voltage from increasing when the output voltage reaches the threshold value. Additional methods and multi-output power supplies are also disclosed.

Abstract: A cost effective solution for power factor correction in power devices operating at two widely separated input voltages comprises two unequal power rails. One power rail is optimized for operation at high line voltage only, while the other power rail is designed only for low line voltage. When operating at high line voltage, the second rail is disabled. At low line, both power rails are enabled but by virtue of unequal boost inductors, the high line power rail handles only about 30% of the power while the low line power rail handles the remaining power. Hence, the efficiency at high line voltage is maximized. As the inductance used in the high line power rail is much higher in value, it stays in continuous conduction mode for all load conditions and hence the power factor is significantly improved.

Abstract: A method of operating a switching power converter having at least one power switch controlled by a drive signal having a switching frequency is disclosed. The method includes monitoring an output power of the switching power converter, determining whether the output power has decreased below a threshold level and, in response to the output power decreasing below the threshold level, changing the switching frequency of the drive signal from a first switching frequency to a second switching frequency when an operating condition of the switching power converter is satisfied. Also disclosed are controllers and switching power converters (including PFC converters).

Abstract: A cost effective solution for construction of high frequency, double ended, isolated, push pull, center tapped power transformers operating in continuous/discontinuous mode with minimized winding proximity losses comprises at least two identical sets of windings with identical coupling coefficients. Each set of windings consists of at least one primary winding and at least one secondary winding tightly coupled to each other. Both the sets of windings are loosely coupled to each other with a magnetic field isolating separator.

Abstract: Methods of regulating an output voltage of a multi-output isolated power converter are disclosed. One method includes allowing the output voltage to vary unregulated when the output voltage is below a threshold value and preventing the output voltage from increasing when the output voltage reaches the threshold value. Additional methods and multi-output power supplies are also disclosed.

Abstract: A method of controlling a power converter having at least one switching device for supplying an output voltage and a load current to a load is disclosed. The method includes sensing the output voltage and sensing the load current. The method further includes controlling a duty cycle of the switching device according to the sensed output voltage and a voltage control loop when a rate of change of the load current does not exceed a threshold level. The method also includes adjusting the duty cycle of the switching device set by the voltage control loop when the rate of change of the load current exceeds the threshold level.