572 results about "Smoothing circuits" patented technology

A charging monitor has: a switch that is disposed between a load section having a storage battery and an external AC power supply supplying a current to the load section via a plurality of lines and interrupts the supply of the current from the external AC power supply to the load section; a current detection circuit that outputs a detection signal corresponding to a difference in level between currents flowing through the lines; a suppression circuit that suppresses a DC component contained in the detection signal; a filter circuit that filters a plurality of frequency components contained in the detection signal so that attenuation increases as a frequency becomes high; a rectifier smoothing circuit that rectifies and smoothens an output signal obtained when the detection signal passes through the filter circuit and the suppression circuit; and an electric leakage determination circuit that detects an electric leakage and shuts off the switch when the level of the signal smoothened by the rectifier smoothing circuit exceeds a preset reference level.

A switching power supply device has a configuration in which a series combination of a first switching circuit and an input power source is connected in series with a series combination of a primary winding of a transformer and an inductor, a series combination of a second switching circuit and a capacitor is connected in parallel to the series combination of the primary winding of the transformer and the inductor, and the secondary winding of the transformer is provided with a rectifying smoothing circuit including a rectifying element. The first switching circuit is made up of a parallel connection circuit including a first switching element, a first diode, and a first capacitor. The second switching circuit is made up of a parallel connection circuit including a second switching element, a second diode, and a second capacitor. A switching controlling circuit is provided adapted to turn the first and second switching elements on and off alternately, with a period of time when both switching elements are off is interposed, and a capacitor is connected in parallel to the rectifying diode in the rectifying smoothing circuit.

A power-supply unit which comprises a transformer, a full bridge circuit consisting of four arm switches provided on a primary side of the transformer, a rectifier and smoothing circuit including two synchronous rectifier switches provided on a secondary side of the transformer, a choke coil, and a capacitor, an output terminal provided in the rectifier and smoothing circuit, a control circuit controlling ON/OFF of the four arm switches of the full bridge circuit and the two synchronous rectifier switches of the rectifier and smoothing circuit, a resonant inductor consisting of a leakage inductor component of the transformer and a parasitic inductor component of wirings on the primary side of the transformer, and a resonant capacitor consisting of a parasitic capacitor component of the arm switches of the full bridge circuit, and in which the control circuit comprises timing variable means which varies switching timings of the two synchronous rectifier switches of the rectifier and smoothing circuit based on an output current flowing in the output terminal provided in the rectifier and smoothing circuit.

An electric power converter includes a capacitor, a bridge circuit that includes a plurality of switching elements, a transformer, a secondary side rectifier circuit, a smoothing circuit, a detector that detects a value based on at least one of a capacitor voltage and a current flowing from the capacitor, and a control device that outputs a primary side drive signal to turns on/off each of the plurality of switching elements at a switching frequency, the control device increasing the switching frequency when the detected value increases, the control device reducing the switching frequency when the detected value decreases.

A switching power supply capable of reducing the size as well as noise is provided. A switching element is connected in series with a primary winding of a transformer, a rectifier/smoothing circuit is connected with a secondary winding and a wave-shaping circuit is connected with an auxiliary winding. An operating voltage of a control circuit controlling ON/OFF of the switching element is supplied from a connection node between the primary winding of the transformer and the switching element. The control circuit includes: an output voltage detection circuit that obtains, from a voltage output from the wave-shaping circuit, a feedback voltage in proportion to a voltage output from the rectifier/smoothing circuit and generates a signal for PWM control of the switching element; and a bottom detection circuit that detects, from the voltage output from the wave-shaping circuit, a bottom level of a ringing voltage. The control circuit switches the switching element from OFF to ON in accordance with a signal output from an oscillator internal to the control circuit or a signal output from the bottom detection circuit.

A switching power source apparatus can reduce the size of a transformer and realize the zero-voltage switching of a switch. The apparatus is compact, highly efficient, and low in noise. The apparatus has a series circuit connected to each end of a DC power source (Vdc1) and including a primary winding (5a) of a transformer (T) and a main switch (Q1), a rectifying-smoothing circuit to rectify and smooth a voltage that is outputted from a secondary winding (5b) when the main switch (Q1) is turned on, a series circuit connected to each end of the primary winding (5a) and including an auxiliary switch (Q2) and a clamp capacitor (C1), a series circuit connected to each end of the main switch (Q1) and including a diode (Dx1) and a snubber capacitor (Cx), a series circuit connected to a node between the diode (Dx1) and the snubber capacitor (Cx) and a node between the auxiliary switch (Q2) and the clamp capacitor (C1) and including an auxiliary winding (5x) and a diode (Dx2), and a control circuit (10) to alternately turn on/off the main switch (Q1) and auxiliary switch (Q2). When the main switch (Q1) is turned on, the snubber capacitor (Cx) is discharged through the auxiliary winding (5x) to the clamp capacitor (C1). When the main switch (Q1) is turned off, the snubber capacitor (Cx) is charged, to relax the inclination of a voltage increase of the main switch (Q1).

A constant current output control method and device for a switching power supply circuit for constant current output control of an output current I_2o of a rectifying smoothing. An OFF adjustment time T3 is:

T3=T2×(Np÷Ns×Ip_ref÷2÷I_2oset−1)−T1  (1)

• • in which, I_2oset represents a set output current of the rectifying smoothing circuit, Np represents a number of turns of a primary winding, Ns represents a number of turns of a secondary winding, T1 being a fixed time representing an ON time, Ip_ref representing a reference peak current flowing in the primary winding, and T2 representing an output time during which output is generated from the rectifying smoothing circuit. Output current I_2o during an oscillation period T becomes set output current I_2oset, and constant current output control can be executed by repeating this method.

A resonant switching power source apparatus has a first switching element and second switching element being connected in series between output terminals of a DC power source and are alternately turned on and off; a series resonant circuit having a primary winding of a transformer and a current resonance capacitor and connected in parallel with the second switching element; a controller to control the first and second switching elements; a rectifying/smoothing circuit to rectify and smooth a voltage, which is generated on a secondary winding of the transformer during an ON period of the second switching element, and output the rectified-smoothed voltage; a current detector to detect a current passing through the series resonant circuit; and an overcurrent protector to turn off the first and second switching elements for a predetermined period so that excitation energy of the transformer is reset, if the current detector detects a predetermined current value.

A switching power supply device of the invention includes: a switching circuit for interrupting direct current to generate a pulse voltage; a transformer including a primary winding, a secondary winding, and a core for magnetically coupling the primary winding and the secondary winding; a multi-layer wiring board having wiring lines constituting the primary winding and the secondary winding; a rectifier circuit for rectifying an alternating current; a smoothing circuit for suppressing ripple; and a control circuit for controlling an output voltage from the smoothing circuit. The multi-layer wiring board is provided with at least the switching circuit and the rectifier circuit and is arranged on a main wiring board, and the control circuit is arranged on the main wiring board.

A power factor correction circuit includes a first rectifier to rectify an AC voltage, a series circuit connected to an output of the first rectifier and including a step-up reactor and a switching element, a rectifying-smoothing circuit connected to both ends of the switching element and including a second rectifier and a smoothing capacitor, an input voltage detector to detect an output voltage of the first rectifier, an output voltage detector to detect a voltage across the smoothing capacitor, an error amplifier to amplify an error between the output voltage signal and a reference voltage, and a controller to determine an ON/OFF duty ratio of the switching element according to the amplified error signal and a result of a calculation carried out on the input voltage signal and output voltage signal.

A switching power supply unit which contains a secondary battery for backup and a circuit for controlling the charging and discharging of the secondary battery in its enclosure and which properly manages the charging and discharging of the secondary battery. A switching power supply circuit includes a rectifying and smoothing circuit for smoothing alternating-current input from commercial power supply Vin at normal operation time, a battery pack charged by a DC—DC converter which can continuously output a predetermined direct-current power supply voltage for supplying power supply voltage to the DC—DC converter at the time of a stoppage in alternating-current input, a charging circuit section for controlling the charging and discharging of the battery pack, and a charging and discharging control circuit. The battery pack and circuits, such as the DC—DC converter, are mounted in the same unit enclosure.

A DC-DC converter includes a switch, a rectifier, a smoothing circuit, and a control circuit. The control circuit includes an output detection circuit for outputting an error signal, a current detection circuit for outputting a current detection signal in a period in which at least the switch is OFF, a first circuit for outputting a first signal for setting a timing of turning ON of the switch according to a comparison result between the error signal and the current detection signal, and a second circuit for outputting a second signal for setting an ON time of the switch, according to a reduction in output power from the smoothing circuit, so that the ON time of the switch is reduced, and generates the control signal, based on the first and second signals.

A switching power supply unit is provided, which may supply stable output while manufacturing cost is held down. In a smoothing circuit, a magnetic flux in a first circular magnetic path, a magnetic flux in a second circular magnetic path, a magnetic flux generated by a current flowing through a choke coil, and a magnetic flux generated by a current flowing through another choke coil are shared by one another in the inside of a common magnetic core. A current flowing through two choke coils and a current flowing through different, two choke coils are balanced, and thus stabilized. Moreover, in the smoothing circuit, since such a balanced state is automatically kept, a characteristic value of an element or the like need not be adjusted.

A switching circuit arranged to switch the input of an input power supply is connected to a primary winding of a transformer at a primary side of the transformer. A digital control circuit including a switching controller arranged to output control pulses to the switching circuit and a rectifying/smoothing circuit connected to secondary windings of the transformer are disposed at a secondary side of the transformer. The digital control circuit outputs the control pulses via a pulse transformer, calculates the input power-supply voltage on the basis of the on-duty cycle of the control pulses, the output voltage, and the ratio of the number of turns of the primary winding to the number of turns of the secondary windings of the transformer, and performs converter control in accordance with the calculated input power-supply voltage.

There is provided a non-contact power transfer apparatus performing non-contact power transfer from a power transmission coil L1 to a power reception coil L2 using electromagnetic induction. The non-contact power transfer apparatus has: a power transmission unit 10 including the power transmission coil L1, a power transmission circuit 1, a current detection circuit 3, unit detection means 4 and a first microcomputer 2 with a control circuit for controlling each of the circuits; and a power reception unit 30 including the power reception coil L2, a rectification smoothing circuit 31, a series regulator 34, a charge battery unit 40 with a rechargeable battery, a switching element 33 for pulse-charging and a second microcomputer 32 with a control circuit for controlling the series regulator and the switching element.

With this structure, the non-contact power transmission apparatus can be safe, reduce unnecessary power loss and prevent heat generation even when a foreign matter like metal is placed close thereto.

Disclosed is an active constant power supply apparatus, which rectifies power having various intensities and frequencies without using a high capacity condenser for a smoothing circuit which degrades the power factor of a circuit, and supplies constant power to a load. The active constant power supply apparatus includes an AC power supplier for supplying AC power; a rectifying circuit which receives AC power from the AC power supply unit and rectifies the received power; a driving coil connected in series to the load receiving power from the rectifying circuit; a power switch which switches the current passing through the driving coil and the load on/off; a pulse-type driving signal generator connected to a gate terminal of the power switch to control the switching on/off operation of the power switch; a turn-off decider which generates a turn-off signal when the current flowing along the driving coil has a value higher than the designed value, so as to turn off the power switch; and a pulse width controller which measures the control period ranging from the switch-on time of the driving signal generator to the switch-off time of the turn-off decider, and controls the driving pulse width of the driving signal generator such that the driving pulse width coincides with the control period.