Abstract: To disclose several zero-voltage-switching (ZVS) power inversion circuits, a modified pulse-width modulation control scheme is employed. It includes two driver-signal pairs. Each pair has a near 50% duty ratio driver signal and a pulse-width modulation driver signal. Because the combination timing waveform of the two driver signals of each pair resembles to a letter T, the control scheme is thus briefly named as double T (TT) control. In addition to achieving zero-voltage switching performance for high frequency operation, the disclosed power inversion circuits can alleviate the potential shoot-through problem existed in phase-shift control full-bridge power inversion circuits. Consequently, reliability performance can be improved.

Abstract: Employing a novel TT control scheme, several ZVS power inversion circuits are disclosed. In addition to achieving zero-voltage switching performance for high frequency operation, the disclosed power inversion circuits can alleviate or eliminate the potential shoot-through problem existed in phase-shift control full-bridge power inversion circuits. Consequently, reliability performance can be improved.

Abstract: A soft-switching and low input current ripple inverter circuit is disclosed. It includes two paralleled dual-switch forward inverter circuits with a single transformer, two clamping diodes, and one coupling capacitor. It has voltage-clamping function on the switches with a lossless snubber at the turn-off instant and provides enough leakage energy to achieve zero-voltage switching operation with low input current ripple feature. Two set of the driver signals with 180 phase shift each other are used to control the switches of said first and second dual-switch forward inverters, respectively. Each set of driver signals includes one PWM signal (D) and one near 50% duty cycle driver signal. Employing the proposed inverter circuit, the switch's turn-on voltage can be reduced to half input voltage compared to its prior art circuits. Consequently, the switching losses are thus reduced and efficiency is improved, especially in light-load operation.

Abstract: A soft-switching and low input current ripple inverter circuit is disclosed. It includes two paralleled dual-switch forward inverter circuits with a single transformer, two clamping diodes, and one coupling capacitor. It has voltage-clamping function on the switches with a lossless snubber at the turn-off instant and provides enough leakage energy to achieve zero-voltage switching operation with low input current ripple feature. Two set of the driver signals with 180 phase shift each other are used to control the switches of said first and second dual-switch forward inverters, respectively. Each set of driver signals includes one PWM signal (D) and one near 50% duty cycle driver signal. Employing the proposed inverter circuit, the switch's turn-on voltage can be reduced to half input voltage compared to its prior art circuits. Consequently, the switching losses are thus reduced and efficiency is improved, especially in light-load operation.

Abstract: A soft-switching and low input current ripple power inversion circuit, in which the inversion circuit is connected in parallel to an input DC voltage source and includes a top cell, a bottom cell and at least one transformer, in which the top cell and the bottom cell have its individual impedance adjusting unit of which the impedance can easily be adjusted to obtain the required equivalent resonant inductance or capacitance. Thus, the semiconducting switches therein can be soft-switched alternately to reduce the switching loss. Moreover, the inversion circuit can be modified by adding at least one middle cell inserted between the top cell and the bottom cell to reduce the voltage stress on the semiconductor switch. Consequently, low voltage rating semiconductor switch accompanied with lower RDS(on), conduction losses can be reduced to improve the converter efficiency.

Abstract: A soft-switching and low input current ripple power inversion circuit, in which the inversion circuit is connected in parallel to an input DC voltage source and includes a top cell, a bottom cell and at least one transformer, in which the top cell and the bottom cell have its individual impedance adjusting unit of which the impedance can easily be adjusted to obtain the required equivalent resonant inductance or capacitance. Thus, the semiconducting switches therein can be soft-switched alternately to reduce the switching loss. Moreover, the inversion circuit can be modified by adding at least one middle cell inserted between the top cell and the bottom cell to reduce the voltage stress on the semiconductor switch. Consequently, low voltage rating semiconductor switch accompanied with lower RDS(on), conduction losses can be reduced to improve the converter efficiency.

Abstract: The present invention relates to a near zero current-ripple inversion circuit including top and bottom cells, a transformer (T1) comprising primary windings (P1, P2) and a secondary winding (S1), and at least one middle cell connected in series between the top and bottom cells. The top cell comprises two capacitors (C1, C2) and a switch (Q1) each connecting to the middle cell, and an inductor (Lr1) and the primary winding (P1) connected in series between the capacitor (C1) and switch (Q1), wherein the switch (Q1) is connected to the capacitors (C1, C2) respectively. The bottom cell comprises a capacitor (C3) and a switch (Q2) each connecting to the middle cell, and an inductor (Lr2) and the primary winding (P2) connected in series between the capacitor (C3) and switch (Q2), wherein the primary winding (P2) is connected to the middle cell, and the capacitor (C3) and switch (Q2) are connected.

Abstract: The present invention relates to a near zero current-ripple inversion circuit including top and bottom cells, a transformer (T1) comprising primary windings (P1, P2) and a secondary winding (S1), and at least one middle cell connected in series between the top and bottom cells. The top cell comprises two capacitors (C1, C2) and a switch (Q1) each connecting to the middle cell, and an inductor (Lr1) and the primary winding (P1) connected in series between the capacitor (C1) and switch (Q1), wherein the switch (Q1) is connected to the capacitors (C1, C2) respectively. The bottom cell comprises a capacitor (C3) and a switch (Q2) each connecting to the middle cell, and an inductor (Lr2) and the primary winding (P2) connected in series between the capacitor (C3) and switch (Q2), wherein the primary winding (P2) is connected to the middle cell, and the capacitor (C3) and switch (Q2) are connected.

Abstract: A circuit used to convert DC input to AC output comprises a transformer and three series sub-circuits. The first series sub-circuit is connected in parallel with the DC input and comprises first and second capacitors connected in series. The secondary series sub-circuit is connected in parallel with the DC input and comprises a first primary winding of the transformer, a clamping capacitor and a second primary winding of the transformer sequentially connected in series. The third series sub-circuit connected in parallel with said clamping capacitor and comprises first and second switches connected in series. The center nodes of the first and third series sub-circuits are connected together. Thus, while a secondary winding of the transformer provides AC voltage, the circuit is able to effectively reduce current ripple and decrease voltage stress on semiconductor switch with minimum component count. Similar topologies may be used for rectification instead of inversion.

Abstract: A high voltage gain power converter includes: a main switch element; an assistant switch element; a first inductive element, a first switch element, and a first capacitive element; and a second inductive element, a second switch element, and a second capacitive element. The first inductive element is connected between an input node and first switch element. The first capacitive element, connected between the first switch element and ground, provides a first boost output voltage. The second inductive element is connected between the main switch element and first capacitive element. The second switch element is connected to a common node of the second inductive element and main switch element. The second capacitive element, connecting the second switch element to a first node, provides a second boost output voltage. The assistant switch element is connected between the first inductive element and common node of the second inductive element and main switch element.

Abstract: A circuit used to convert DC input to AC output comprises a transformer and three series sub-circuits. The first series sub-circuit is connected in parallel with the DC input and comprises first and second capacitors connected in series. The secondary series sub-circuit is connected in parallel with the DC input and comprises a first primary winding of the transformer, a clamping capacitor and a second primary winding of the transformer sequentially connected in series. The third series sub-circuit connected in parallel with said clamping capacitor and comprises first and second switches connected in series. The center nodes of the first and third series sub-circuits are connected together. Thus, while a secondary winding of the transformer provides AC voltage, the circuit is able to effectively reduce current ripple and decrease voltage stress on semiconductor switch with minimum component count. Similar topologies may be used for rectification instead of inversion.

Abstract: This invention discloses apparatus and methods for increasing the duty cycle of the single ended power converters surpass 50 percent limitation by adding active switch-capacitor network to the primary circuit and several inversion circuits can be realized to convert a DC input to an AC output. The circuits comprise two series circuits, at least one clamp clamping capacitor, and at least one transformer. The first series circuit includes one active switch paralleled with a diode, one capacitor and at least one transformer primary. The second series circuit includes at least one active switch and at least one transformer primary. At least one clamp clamping 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.

Abstract: A high voltage gain power converter includes: a main switch element; an assistant switch element; a first inductive element, a first switch element, and a first capacitive element; and a second inductive element, a second switch element, and a second capacitive element. The first inductive element is connected between an input node and first switch element. The first capacitive element, connected between the first switch element and ground, provides a first boost output voltage. The second inductive element is connected between the main switch element and first capacitive element. The second switch element is connected to a common node of the second inductive element and main switch element. The second capacitive element, connecting the second switch element to a first node, provides a second boost output voltage. The assistant switch element is connected between the first inductive element and common node of the second inductive element and main switch element.

Abstract: A power converter capable of improving converter's efficiency and achieving zero-voltage-switching is provided, in which a first series circuit is connected in parallel with a direct current (DC) power supply and has a first inductor, a first primary winding, first and second switching elements connected in series. A second series circuit is connected in parallel with the DC power supply and has third and fourth switching elements, a first capacitor, a second primary winding and a second inductor connected in series. A second capacitor is connected between a first node between the first primary winding and the first switching element in the first series circuit and a second node between the fourth switching element and the second primary winding in the second series circuit. A third node between the first and second switching elements is connected to a fourth node within the second series circuit.

Abstract: A power converter capable of improving converter's efficiency and achieving zero-voltage-switching is provided, in which a first series circuit is connected in parallel with a direct current (DC) power supply and has a first inductor, a first primary winding, first and second switching elements connected in series. A second series circuit is connected in parallel with the DC power supply and has third and fourth switching elements, a first capacitor, a second primary winding and a second inductor connected in series. A second capacitor is connected between a first node between the first primary winding and the first switching element in the first series circuit and a second node between the fourth switching element and the second primary winding in the second series circuit. A third node between the first and second switching elements is connected to a fourth node within the second series circuit.

Abstract: 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.

Abstract: A circuit used to convert a DC input to an AC output comprises a pair of series circuits, one or two capacitors, and one transformer. Each of the series circuits is in parallel with the DC input and comprises a pair of series-connected switches and at least one transformer primary. Each capacitor couples the two series circuits, and is attached to each series circuit at a node between the respective transformer primary and switch. The center nodes between two series-connected switches are connected together. At least one secondary on the transformer provides the AC output. Optionally, multiple transformers may be utilized. Similar topologies may be used for rectification instead of inversion.

Abstract: A circuit used to convert a DC input to an AC output comprises a pair of series circuits, one or two capacitors, and one transformer. Each of the series circuits is in parallel with the DC input and comprises a pair of series-connected switches and at least one transformer primary. Each capacitor couples the two series circuits, and is attached to each series circuit at a node between the respective transformer primary and switch. The center nodes between two series-connected switches are connected together. At least one secondary on the transformer provides the AC output. Optionally, multiple transformers may be utilized. Similar topologies may be used for rectification instead of inversion.

Abstract: A PWM controlling circuit includes a signal generator and two PWM controllers. The signal generator comprises an oscillator, a plurality of inverters, and two RC delay networks. The oscillator and the inverters are composed of elementary elements, respectively, such as diodes, resistors, inverters and capacitors. The PWM controlling circuit in accordance with the present invention can be implemented with low cost, and the duty cycles thereof are not limited to 50%.

Abstract: A forward converter for a switching power supply includes a direct current voltage source having a positive electrode and a negative electrode, a transformer having four identical primary windings each having a first end and a second end and a secondary winding connected to a load, the first end of a first primary winding and the second end of a fourth primary winding being connected to the positive electrode of the voltage source, the first end of a third primary winding and the second end of a second primary winding are connected to the negative electrode of the voltage source, two series-connected power switches connected between the second end of the first primary winding and the first end of the second primary winding and defining a common point between the power switches for simultaneously turning on and off in response to a control signal, a first diode connected between the common point of the power switches and the first end of the fourth primary winding, a second diode connected between the second e