586 results about "Smoothing circuits" patented technology

A low-cost PFC converter capable of detecting an inductor current including a DC component and performing appropriate correction of a power factor with low loss includes a diode bridge that rectifies an AC voltage input from an AC input power supply Vac, a series circuit including an inductor and a switching element, a rectifying and smoothing circuit that is connected in parallel to the switching element and that includes a diode and a smoothing capacitor, and a digital signal processing circuit that performs on / off control on the switching element so that an input current input from the AC input power supply Vac has a similar waveform with respect to an AC voltage. A current flowing through the inductor during an off period of the switching element is detected using a current detecting resistor, and a decreased voltage of the current detecting resistor is sampled at the middle of the off period of the switching element, thereby detecting an average value of the input current.

A transformer has a primary winding connected between a pair of dc input terminals via a switch, a secondary winding connected between a pair of output terminals via a first rectifying and smoothing circuit, and a tertiary winding connected to a second rectifying and smoothing circuit for feeding a switch control circuit. Included in the switch control circuit is a switch control pulse generator circuit whereby the switch is driven to provide a constant dc voltage at the output terminals. A mode selector circuit is connected to the switch control pulse generator circuit to cause the switch to be driven continuously under normal load, and at intervals under light load. The intermittent driving of the switch is suspended, and the switch driven continuously, in the event of a drop in the output voltage of the second rectifying and smoothing circuit to a predefined value during operation in light load mode.

A series circuit in which a first switching element and a second switching element are connected in series at both ends of an output of an input rectifier circuit for rectifying an alternating current of an alternating current power supply, a resonant circuit in which a primary winding of a transformer and a current resonant capacitor are connected in series at both ends of the first switching element or the second switching element, a rectifying and smoothing circuit for rectifying and smoothing a voltage generated across a secondary winding of the transformer during an on-period of the first switching element or the second switching element, a control circuit for alternately turning on / off the first switching element and the second switching based on a voltage from the rectifying and smoothing circuit, and a voltage detecting circuit for outputting a voltage detecting signal when a voltage at both ends of one switching element of the first switching element and the second switching element, which is turned on at a time of transmitting electric power to the rectifying and smoothing circuit, becomes equal to a predetermined voltage or more. The control circuit turns on the other switching element of the first switching element and the second switching element based on the voltage detecting signal from the voltage detecting circuit.

A DC-DC converter of the present invention includes: an activation circuit which activates a control circuit for controlling a turning on and off of a switching element; a second rectifying and smoothing circuit which supplies an output voltage, as a power supply, to the control circuit, the output voltage being obtained by rectifying and smoothing a voltage in a tertiary winding of a transformer; an overcurrent protection circuit which limits an output current to be supplied to a load when overloaded; an overcurrent detection circuit which detects that the load is in an overcurrent state, and which outputs a detection signal during a period when the overcurrent protection circuit is operated; and an activation current switching circuit which switches outputs from the activation circuit.

A buck-boost converter includes: a buck converter section including a first switch, a first rectifier, and an inductor; a boost converter section sharing the inductor and including a second switch, a second rectifier, and a smoothing circuit; and a control circuit for generating and outputting a first driving signal for opening and closing the first switch and a second driving signal for opening and closing the second switch. The control circuit includes: an error amplifier circuit for amplifying an error between an output value from the smoothing circuit and a predetermined voltage value to thereby generate and output an error signal; an oscillator circuit for generating and outputting a triangular wave signal having a predetermined cycle; a compensatory signal generation circuit for generating and outputting a compensatory signal, which oscillates in a cycle that is at least twice the cycle of the triangular wave signal; a control signal generation circuit for adding together the error signal and the compensatory signal to thereby generate and output a control signal; and a comparator circuit for comparing the triangular wave signal with the control signal to generate and output the first or second driving signal.

There is provided a high-efficiency DC-DC converter which comprises a voltage resonance circuit to which electric power from a low-voltage direct-current power supply, including a household fuel cell and a solar cell, is input and performs DC-AC conversion by zero-voltage switching, an insulating high-frequency transformer which transmits the converted power, a current resonance circuit which is provided on the secondary side of the transformer and performs zero-current switching, a rectifier circuit which rectifies the output from the current resonance circuit, and a smoothing circuit which rectifies the output from the rectifier circuit.