Abstract: A multi-mode active clamping power converter comprises an input inductor, a down-bridge switch, an up-bridge switch, a first energy-storing capacitor, a clamping capacitor, a resonant inductor, a magnetizing inductor, a transformer, an output diode and an output capacitor. The input inductor has a boundary inductance value, wherein an input voltage source is operated between a first voltage and a second voltage and the boundary inductance value is set according to the first voltage and a heavy load so as to be served as an initial condition of the multi-mode active clamping power converter, and then the input inductor is operated in a boundary conduction mode.

Abstract: A flyback active clamping power converter is disclosed. The flyback active clamping power converter comprises an input inductor, a down-bridge switch, an up-bridge switch, a first energy-storing capacitor, a clamping capacitor, a resonant inductor, a magnetizing inductor, a transformer, an output diode and an output capacitor. When a resonant frequency generated by the resonant inductor and the clamping capacitor in the flyback active clamping power converter is substantially equal to a switching frequency, the output diode is able to perform a zero current switching in the whole load range.

Abstract: A flyback power converter is disclosed. The flyback power converter includes a voltage transformer, a main switch, a synchronous rectification switch, a synchronous rectification control circuit, a sampling circuit and an operation circuit. A control end of the main switch receives a main switch signal so as to control the main switch. The synchronous rectification control circuit transmits control signal to control end of the synchronous rectification switch according to sensing signal received. The sampling circuit samples the state of the synchronous rectification switch so as to generate first logic signal and second logic signal. The operation circuit executes timing for charging/discharging according to the first and the second logic-signal, so as to output switch cut-off pulse signal to a voltage-dividing circuit. If voltage of the sensing signal is lower than predetermined threshold voltage, the synchronous rectification switch enters into cut-off state according to the control signal.

Abstract: A DC uninterruptible power supply system includes plural uninterruptible power supply devices, each of which includes a power cord, a battery module, a voltage detecting circuit, a current detecting circuit, and a control unit. When the voltage detecting circuit detects that a voltage at the power cord is lower than a first preset value, the control unit controls the battery module to output electrical power to the power cord. When the current detecting circuit detects that current of another uninterruptible power supply device is smaller than a second preset value, the control unit controls a switch to permit current flow to the another uninterruptible power supply device.

Abstract: A battery module includes a plurality of battery units, each of which supplies electrical power to a load through a respective linear regulator. In a method for managing supply of electrical power by the battery module, a number of battery units that supply electrical power to the load is controlled according to magnitude of a current required by the load, so as to reduce power loss in the linear regulators.

Abstract: A direct current (dc) uninterruptible power system is disclosed. The dc-based uninterruptible power system includes a multiplexer, a battery unit, a linear regulator, a switch-transistor, a voltage comparator and micro controller. The multiplexer receives a first control signal, a first reference voltage and a second reference voltage and outputs a control voltage according to the first control signal. The switch-transistor has a body diode and the body diode has a conduction voltage. When the dc-based uninterruptible power system is non-discharge mode, the switch-transistor is switched-off and the linear regulator receives the first reference voltage, so that the subtraction of the output voltage and the power-supply voltage is smaller than the conduction voltage to cutoff the body diode.

Abstract: A flyback power converter is disclosed. The flyback power converter includes a voltage transformer, a main switch, a synchronous rectification switch, a synchronous rectification control circuit, a sampling circuit and an operation circuit. A control end of the main switch receives a main switch signal so as to control the main switch. The synchronous rectification control circuit transmits control signal to control end of the synchronous rectification switch according to sensing signal received. The sampling circuit samples the state of the synchronous rectification switch so as to generate first logic signal and second logic signal. The operation circuit executes timing for charging/discharging according to the first and the second logic-signal, so as to output switch cut-off pulse signal to a voltage-dividing circuit. If voltage of the sensing signal is lower than predetermined threshold voltage, the synchronous rectification switch enters into cut-off state according to the control signal.

Abstract: A voltage control method for a power converter includes: acquiring a current of a first primary side winding of a transformer circuit of the power converter; integrating the acquired current to obtain an average voltage; comparing the average voltage with a reflected voltage associated with a current of a secondary side winding of the transformer circuit; and adjusting a duty cycle of a switch of the power converter based on an obtained comparison result for adjustment of an output voltage of the power converter.

Abstract: An electric power converting device includes a rectifier, a flyback voltage converter and a non-isolated voltage regulator. The rectifier is for converting an alternating current (AC) signal received from an AC power source into a direct current (DC) signal. The flyback voltage converter is electrically connected to the rectifier for transforming voltage of the DC signal from the rectifier to output a regulated DC signal. The non-isolated voltage regulator is electrically connected to the flyback voltage converter for reducing a voltage ripple of the regulated DC signal from the flyback voltage converter and for outputting an output voltage to a load.