An AC-to-DC power converter configured to provide power factor correction and a single isolated low-voltage output. The power converter includes a single-stage resonant power converter including an isolation transformer, a resonant tank, a rectifier, and a bulk storage capacitor coupled to an output of the isolation transformer. In typical applications, at least one non-isolated power converter is coupled to the output of the single-stage isolated power factor correction converter.

Resonant power factor correction converter

A flyback converter high voltage power supply which includes two switches (Q10, Q11) operating in push pull fashion to provide alternate polarity energy pulses to a load (30). A main component of the power supply is a transformer (T10), the primary winding of which is divided into halves (P1, P2). The secondary may also be split into halves (S1, S2), or may be configured without a split so long as the secondary and rectifier combination result in full wave rectification. The first of the two switches (Q10) couples an input voltage (Vin) across the first primary half (P1) to store energy in the magnetic core during a first time interval, and at the end of the first time interval disconnects the first primary half (P1) from the input voltage (Vin). During a second time interval, the energy stored in the magnetic core during the first time interval is delivered to the load (30) via the secondary winding (S1, S2). The second of the two switches (Q11) similarly couples the input voltage (Vin) across the second primary half (P2) to store energy in the magnetic core during a third time interval, and then disconnects the second primary half (P2) from the input voltage (Vin) at the beginning of the fourth time interval. During the fourth time intevral, the energy stored in the magnetic core is again transferred to the load (30) via the secondary. A duty factor modulator is used to control the switching of the first and second switches (Q10, Q11) to vary the length of the time intervals in reponse to variations in the load and input voltage.

Push pull resonant flyback switchmode power supply converter

A DC to DC power converter is implemented which includes an input switching circuit, an input capacitor, a transformer and an output rectifying switching circuit coupled to the transformer. The input switching circuit consists of a minimum of four transistors which are operated in a timed relationship such that bi-directional currents are developed in both primary windings. The output rectifying switching circuit is operated with switching transistors that provide zero-voltage resonant transition (ZVRT) switching. Timing relationships between the input signals control the ZVRT with switching of the transistors. Bidirectional currents in the primary windings of the single transformer element permit a reduction in volume of the magnetic element and the coils of the transformer for a given level of output power. Overall, converter volume for a given output power is thereby sufficiently reduced to allow a power converter to be mounted on a circuit board, which enables a practical embodiment of a distributed power processing system.

Interleaved bridge converter

A regulated power factor corrected power supply apparatus is provided. The apparatus includes an input rectifier circuit for receiving an input AC voltage and outputting a full-wave rectified DC voltage. A single-stage isolated buck-type converter is coupled with the input circuit. The converter circuit comprises an isolated buck-type converter circuit including an isolation transformer. An output rectifier and semiconductor tap switch are coupled to a secondary winding of the isolation transformer. The tap switch couples a larger portion of the secondary winding to an output bulk capacitor during the portions of the input sinewave half-cycle, which are low in amplitude. The tap switch enables the single-stage isolation buck-type converter to operate over a much larger portion of the input sinewave, but also allows the converter to operate at high-efficiency over the majority of the input sinewave.

High power factor isolated buck-type power factor correction converter

A unipolar ignition of the invention provides a current waveform at the ignitor plug which initially rises relatively slowly, followed by a transition to a fast rising current which quickly peaks and thereafter slowly dissipates. Such a current waveform provides an initially hotter and longer lasting spark which does not harm the ignitor plug of the system or shorten its life expectancy. Neither does the spark create stress on the solid state circuitry which delivers the energy to the ignitor plug. To provide the foregoing spark and current characteristics, an inductor having a saturable core is in series with the ignitor plug, and it provides an initially high inductance which limits the rate of current rise at the plug as energy is transferred from an energy storage device to the plug. As the current through the inductor increases, its core begins to saturate and the effective inductance begins to decrease, allowing the current to rise more quickly. As energy is transferred to the ignitor plug, the increasing saturation, decreasing inductance and increasing current complement one another, causing the rate of current rise to increase quickly to a high value desirable for ignition. Related features of the invention provide for easy diagnostics of the spark and for timing an ignition sequence and providing a repetition rate which aids in a successful ignition.

Apparatus and method for providing ignition to a turbine engine

A resonant type constant voltage supply apparatus has a LC series resonance circuit. Energy stored in both a resonance capacitor and a resonance inductor is directly transferred to the output or input terminal of the apparatus. A control transformer is provided in parallel with the resonance capacitor for deriving the energy stored in the resonance capacitor. The amount of the energy stored in the resonance capacitor can be controlled by changing the switching frequency of the apparatus or the inductance of the control transformer, so as to thereby control the amount of energy transferred to the output or input terminal of the apparatus and thereby stabilize the output voltage of the apparatus.

Resonant type constant voltage supply apparatus

A self-oscillating DC to DC converter which includes either two or four transistors, three transformers (a converting transformer, a driving transformer and a current transformer) and an inductance. The operating frequency of the converter is fixed by the saturation time of the driving transformer. The base currents of the transistors are mainly supplied by the current transformer so as to be in proportion to the collector currents of the transistors. The operating frequency of the converter is kept constant in spite of load fluctuations. The inductance which is connected in series between a winding of the converting transformer and a winding of the driving transformer. The inductance prevents the two or four transistors from being `on` simultaneously.

Masahiro Kosaka

Papers

Resonant type constant voltage supply apparatus

Self-oscillating DC to DC converter