218 results about "Clamp capacitor" patented technology

The DC-DC converter connects a first and a second switching circuit for converting power mutually between direct current and alternating current respectively to a first DC power source and a second DC power source and has a transformer between the AC terminals thereof. Here, between the AC terminals of the second switching circuit and the negative pole terminal of the DC power source, a voltage clamp circuit composed of a series unit of switching devices with a reverse parallel diode and a clamp condenser is connected. An isolated bidirectional DC-DC converter which prevents a reduction in a circulating current at time of buck and an occurrence of a surge voltage at time of voltage boost and realizes highly efficiency, low noise, and miniaturization is provided.

The present invention is directed to an auxiliary active clamp circuit and a method of clamping a voltage of a rectifier switch associated with a power converter. The power converter includes a main active clamp circuit associated with a main power switch coupled to a primary winding of a transformer and a rectifier switch coupled to a secondary winding of the transformer. The main power switch conducts during a main conduction period of the power converter and the rectifier switch conducts during an auxiliary conduction period of the power converter. In one embodiment, the auxiliary active clamp circuit includes an auxiliary clamp capacitor, coupled across the rectifier switch, that stores a clamping voltage substantially equal to an off-state voltage of the rectifier switch. The auxiliary active clamp circuit also includes an auxiliary clamp switch, coupled in series with the auxiliary clamp capacitor, that receives a drive signal from a secondary winding and conducts during the main conduction period thereby clamping a voltage across the rectifier switch at about the clamping voltage.

A bi-directional DC-DC converter has a transformer for connecting a voltage type full bridge circuit connected to a first power source and a current type switching circuit connected to a second power source. A voltage clamping circuit constructed by switching elements and a clamping capacitor is connected to the current type switching circuit. The converter has a control circuit for cooperatively making switching elements operative so as to control a current flowing in a resonance reactor.

A voltage boost power converter circuit, having an input inductor, active switch, and a transformer having primary, secondary and auxiliary windings. A clamping capacitor and a first passive switch are in series across the primary winding. The auxiliary winding and a second passive switch are in series, connected to the node between the clamping capacitor and first passive switch. The active switch is connected between ground the primary winding. A bulk capacitor forms a series loop including the active switch and primary winding. The method efficiently resets a the transformer, by transferring power to a load through the primary winding, and discharging a clamping capacitor through a separate inductively linked winding of the transformer during an ON state; and clamping the active switch voltage with the clamping capacitor, charging the clamping capacitor with a leakage inductance of the transformer, and charging the bulk capacitor during an OFF state.

The invention provides a control method of a flyback converter. The control method is a control method in a mixed control mode; in other words, the flyback converter works in a non-complementation state under light loads, the clamp switch pipe on time is shortened through down conversion, and light load losses are effectively reduced through down conversion; flyback converter works in a fixed-frequency drive complementation state under heavy loads, and the clamp switch pipe on time is prolonged. Compared with the prior art, the control method has the advantages that the voltage stress of a main switch pipe and a clamp capacitor can be effectively reduced, the main switch pipe off losses can be reduced, the clamp circuit current change slope is decreased, the EMI interference is reduced, the secondary current change slope is decreased, and the longer detection reaction time is provided for synchronous rectification. Meanwhile, the working area of a magnetic core in the third quadrant is enlarged, the maximum flux density is reduced, and the size of the magnetic core is reduced.

The invention discloses a non-complementary flyback active clamp converter. The non-complementary flyback active clamp converter comprises a transformer, a main switching tube, a clamp switching tube, a clamp capacitor and a drive module. The drive module outputs main drive signals to the drive end of the main switching tube, and the driving signals are used for controlling the main switching tube to be alternately switched on and switched off. The drive module outputs clamp drive signals to the drive end of the clamp switching tube. The clamp drive signals and the main drive signals have the same period. Each period comprises a first pulse signal which is generated when the switching-on state of the main switching tube is converted to the switching-off state, a second pulse signal which is generated when the main switching tube is in the switching-off state, and a signal which is generated at the remaining time and used for controlling the switching-on and the switching-off of the clamp switching tube, wherein the first pulse signal and the second pulse signal are independent of each other and both used for controlling the switching-on and the switching-off of the clamp switching tube. By the adoption of the non-complementary flyback active clamp converter, it is guaranteed that a high-frequency current generated when the clamp capacitor is charged fully flows through the clamp switching tube and avoids a backward diode of the clamp switching tube.

A low input-current-harmonic three-phase three-level boost rectifier includes an input stage for receiving a three-phase input voltage in relation to a neutral node and an output stage adapted to couple to at least one load. The rectifier further includes one or more switching converter stages, each having a plurality of serially-connected switches coupled to the neutral node, one of the serially-connected switches operating with a fixed duty cycle while the other of the serially-connected switches operating with a variable duty cycle, the fixed duty cycle being a substantially 50% duty cycle and the variable duty cycle being less than or equal to a substantially 50% duty cycle. The serially-connected switches are coupled to clamping diodes and clamping capacitors. The rectifier further includes one or more controllers adapted to vary the switching frequency and/or duty cycle of the plurality of switches based on at least one of a condition of the at least one load or the input voltage and includes one or more decoupling stages, each including one or more inductive elements adapted to inductively decouple the output stage from at least one of the one or more switching converter stages.

The invention discloses a forward-flyback isolated type boost inverter realized by coupling inductors and application thereof, comprising two power switch tubes, two auxiliary switch tubes, four anti-parallel diodes, a switch tube parallel capacitor, two clamp capacitors, two switch capacitors, two output diodes and two coupling inductors respectively provided with two windings. The invention realizes zero-voltage switching on of the power switch tubes through the resonance of the leakage inductance of the two coupling inductors and the switch tube parallel capacitor, absorbs the voltage peak switched off by the switch tubes caused by the leakage inductance and realizes energy lossless transfer by utilizing a clamp circuit comprising the anti-parallel diodes of the switch tubes and the two clamp capacitors, realizes the high gain output of the inverter by utilizing the serial connection of the second windings of the two coupling inductors, further improves the gain of the inverter and lowers the output voltage stress of the diodes by utilizing the switch capacitors and realizes the output zero-current switching off of the diodes by utilizing the leakage inductance of the coupling inductors.

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 dual bridge matrix converter has a line-side converter with controllable switches that receives AC power and provides unidirectional power to high and low DC link lines, and a load-side converter which receives the power from the DC link lines and provides AC power to output lines. A clamp circuit is connected across the DC link lines and includes a series connected diode and a capacitor. Negative DC link current will be conducted through the clamp diode to charge the clamp capacitor to avoid voltage spikes on the DC link lines. A controllable switch may be connected in parallel with the clamp diode and is turned on when the voltage across the clamp capacitor is above a threshold that is greater than the normal peak-to-peak AC input voltage. The switch is turned off when the voltage across the clamp capacitor is lower than the threshold voltage.

Several inversion circuits used to convert a DC input to an AC output comprise two series circuits, at least one clamp capacitor, and at least one transformer. Each of the series circuits is in parallel with the DC input. The first series circuit includes one switch network and at least one transformer primary. The second series circuit includes one voltage-clamp network and at least one transformer primary. At least one clamp capacitor couples the first and the second series circuits, and is attached to each series circuit at a node between the respective transformer primary winding. The voltage-clamp network may be implemented with two of the three sub-circuits connected in series: a diode, a resister-capacitor-diode, and a MOSFET-capacitor.

A DC converter has a transformer with loosely coupled primary and secondary windings, a main switch connected in series with the primary winding of the transformer, and a series circuit connected to ends of one of the primary winding and main switch. The series circuit includes a clamp capacitor and an auxiliary switch. The main and auxiliary switches are alternately turned on/off so that a voltage of the secondary winding of the transformer is synchronously rectified with synchronous rectifiers and is smoothed with smoothing elements, to provide a DC output. The DC converter also includes a tertiary winding provided for the transformer, tightly coupled with the primary winding, and configured to generate a voltage that drives the synchronous rectifiers.

The invention relates to the field of switching converters, and particularly relates to a flyback active clamp-type switching converter control circuit and a control method thereof. The active clamp flyback circuit of the invention can realize reduced frequency and ZVS, and comprises a main power circuit, a clamp circuit, and an output rectification filter circuit, wherein a transformer and a main switching tube are connected to form the main power circuit; a clamp switching tube and a clamp capacitor and a clamp diode are connected to form the clamp circuit; and an output rectification diode and an output capacitor are connected to form the output rectification filter circuit. In comparison with the prior art, reduced frequency in light load can be realized, and the control scheme is flexible; switching loss in no load and loss of a transformer winding and switching tube inner resistance caused by a current effective value are little, no-load power consumption is greatly reduced, and the light-load efficiency is improved.

The invention discloses a mixed clamping back-to-back multi-level AC-DC-AC switching circuit. The mixed clamping back-to-back multi-level AC-DC-AC switching circuit comprises two groups of multi-level switching circuits and a direct current bus capacitor link connected with the two groups of multi-level switching circuits; and the level number of the direct current bus capacitor link is more than or equal to 4. By the mixed clamping back-to-back multi-level AC-DC-AC switching circuit, the dynamic self-balance between all direct current bus capacitors and clamping capacitors can be realized and equal capacitor voltage can be obtained so that the champing capacitors and the direct current bus capacitors complete multi-level boost output and a good condition for the expansion of the capacitance of direct current bus capacitors is created at the same time. The mixed clamping back-to-back multi-level AC-DC-AC switching circuit bears a high-power high-voltage load on the premise of guaranteeing system reliability and good harmonic output characteristics, is flexible in control, quite low in loss, has efficient performance, can realize bidirectional flow and mutual control compensation of reactive power and active power, and is very suitable for alternating current speed regulation or a power grid interconnection technique of different distributed power generating systems.

The invention relates to a high-efficiency and low-cost forward-flyback DC-DC (direct current-direct current) converter topology. The forward-flyback DC-DC converter topology comprises a transformer, a main switch tube, a clamp circuit, a first rectification switch tube, a second rectification switch tube, an LC resonance circuit and an output capacitor, wherein a primary winding of the transformer is connected in series with the main switch tube between a first input end and a second input end; the clamp circuit consisting of a clamp capacitor and a clamp switch tube which are connected in series is connected in parallel with the primary winding or the main switch tube; a secondary winding of the transformer comprises a forward winding and a flyback winding; one end making the current flow into the primary winding is a dotted end of the primary winding; the secondary side of the transformer is connected in a manner that: the dotted end of the forward winding is connected to the first output terminal through the first rectification switch tube, and the dotted end of the flyback winding is connected to the second output terminal through the second rectification switch tube; the LC resonance circuit is connected to the first output terminal and the second output terminal and the unlike ends of the forward winding and the flyback winding so as to switch on or switch off the first rectification switch tube and the second rectification switch tube at zero current; and the output capacitor is connected between the first output terminal and the second output terminal.

The number of necessary sampling and holding capacitors is reduced. A solid-state image pickup device has signal lines to which photoreceiving elements are connected, a clamp circuit that has clamp capacitors in which one terminal is connected to the signal lines and the other terminals are short-circuited, has a switch for applying a reference voltage to the other terminals by the clamping operation, and adds signals from the plurality of photoreceiving elements provided in the row direction along with the clamping operation, adding means (switches and capacitors) which is connected to the other terminals of the clamp capacitors, adds addition signals of the respective photoreceiving element rows outputted from the other terminals and adds the signals of the plurality of photoreceiving elements provided in the column direction; an amplifier connected to the adding means; a switch for resetting the input side of the amplifier; and circuit means (switches and capacitors) for outputting an offset of the amplifier and the signal from the amplifier.

The invention discloses a soft switching three-phase gird-connected inverter additionally provided with a freewheeling path, which comprises an inverter direct current power supply, a three-phase bridge arm formed by six full-control master switches with antiparallel diodes, and output filter inductors respectively connected between the midpoint of each phase of the bridge arm and an alternating current grid, wherein the three-phase bridge arm is connected with a full-control switch with an antiparallel diode, the full-control switch and the six master switches of the three-phase bridge arm are respectively connected with a capacitor in parallel, an auxiliary switch with an antiparallel diode and a serial branch of a clamp capacitor are accessed between the inverter direct current power supply and a direct current bus of the three-phase bridge arm, and a resonance inductor Lr is bridged at two ends of the serial branch, and the auxiliary switch is connected in parallel with the capacitor. The invention is simple in structure, can suppress the reverse recovery of the diodes, and reduces the electromagnetic interference. All switches of the inverter realize zero-voltage switching-on, thus the inverter has the advantages of little switching loss and high circuit efficiency. The inverter can realize control of power factors and harmonic waves for output grid-connected current, and can be used in a grid-connected inverter in various power supplies.

A converter includes a transformer, a main switch, an active clamp circuit, and a control circuit. The transformer includes a primary winding and a secondary winding, and is configured to receive an input voltage and output an output voltage to a load. The main switch is coupled between the primary winding and a primary ground terminal. The active clamp circuit includes an auxiliary switch and a clamp capacitor. The auxiliary switch is coupled to the clamp capacitor in series, and the active clamp circuit is coupled in parallel to the two terminals of the primary winding or the main switch, and is configured to clamp the voltage across the main switch when it is OFF. The control circuit outputs an auxiliary switch control signal to turn on the auxiliary switch when the voltage across the main switch is at its first peak of the resonant voltage.

An isolated switching power supply device includes a main transformer having a primary coil on a primary circuit side and a secondary coil on a secondary circuit side. On the primary circuit side are disposed an input smoothing capacitor, a switching control circuit, a high-side driver, a low-side power switch, a high-side power switch, capacitors, and edge signal-generating circuits. A symmetrical control half bridge converter is thus provided. The secondary circuit side has a voltage clamping circuit including a clamp capacitor, a clamp switch and a diode.

A switching power supply circuit includes a switching element, a converter transformer, a secondary-side rectifying and smoothing circuit, a switching element control unit, a choke coil, a primary-side series resonant circuit, a primary-side parallel resonant circuit, and a series circuit. The switching element implements switching for a direct-current (DC) voltage to convert the voltage into an alternating-current (AC) voltage. The choke coil is supplied with the voltage and is connected to one winding end of the primary winding and one terminal of the switching element. The primary-side series resonant circuit connects a primary-side series resonant capacitor, having a resonant frequency dominated by a leakage inductance. The primary-side parallel resonant circuit connects a primary-side parallel resonant capacitor in parallel to the switching element, having a resonant frequency. The series circuit is formed of a clamp capacitor and an auxiliary switch element which conducts in a non-conducting period of the switching element.

In a DC-DC converter, a smoothing capacitor is connected between DC terminals of the switching circuit, and a smoothing capacitor and a voltage clamp circuit are connected between DC terminals of a switching circuit, the voltage clamp circuit including the switching device and the clamp capacitor. The smoothing capacitors are connected to the DC power sources) in parallel, respectively. The winding of the switching circuit is magnetically coupled to the winding of the switching circuit by the transformer. The DC-DC converter performs a discharging operation for discharging the clamp capacitor between at least one of the step-down operation and a step-up operation and a step-up operation performed thereafter.

A boost device boosts an input voltage to an output voltage across an output capacitor, and includes an output diode coupled to the output capacitor, and a transformer coupled to a first switch, a clamp circuit and a boost circuit. The clamp circuit is coupled across a first winding of the transformer, and includes a clamp capacitor coupled in series to a second switch. The output capacitor is capable of being charged through the output diode with an induced voltage across a second winding of the transformer. The boost circuit is capable of being charged with the induced voltage across the second winding, and of charging the output capacitor so as to boost the output voltage across the output capacitor.