Electric power conversion systems – Current conversion – Using semiconductor-type converter
Patent
1994-12-08
1997-09-02
Wong, Peter S.
Electric power conversion systems
Current conversion
Using semiconductor-type converter
363 21, 363 17, 363 89, H02M 7217
Patent
active
056638779
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND
The present invention relates to a synchronous rectifier, that is impervious to reverse feed.
Feeder devices with synchronous rectifiers are known per se, and are in use as electric power supply devices. In the same way, such devices are known from publications, for example, from O. Kilgenstein, Schaltnetzteile in der Praxis, Wuerzburg, 1992. Each of the known devices has a range of operation that is limited at the top by the maximum output current at which the output voltage is still regulated to the desired value.
If either temporarily or for long periods the current requirement is greater than the capacity of a single device, and the selection of a similar device of greater capacity is not indicated for certain reasons, then these devices are connected in parallel.
If in one of the devices that is connected together in parallel in this manner, an operating state arises in which either the output voltage drops or the oscillator no longer triggers or interrupts the primary transformer, then the devices that are connected in parallel with the device under consideration feed power back into the device that is either temporarily or permanently out of service, which as a rule leads to the destruction of the controlled rectifier or to a collapse of the output voltage.
SUMMARY
The task of the present invention is to create a synchronous rectifier that is impervious to reverse feed, and that is fully capable of operation in all operating states. In one embodiment, the present invention comprises a synchronous rectifier, including a transformer (3) with a primary winding (2), which is supplied on an alternating basis with current from a direct-current source (1) by means of a switch (4) that is controlled by an oscillator, which transformer (3) exhibits a first secondary winding (5) with ends (C, D), additionally including a first MOSFET (6) and a second MOSFET (7), which are connected into the circuit on an alternating basis in time with the oscillator, whereby the one MOSFET (7) fulfills the function of a rectifier diode, and the second MOSFET (6) that of a recovery diode, the drain electrode of the first MOSFET (6) is joined on the one hand with the one end (C) of the first secondary winding (5), and on the other hand, with an output (14) of the apparatus by means of a storage choke (12), the drain electrode of the second MOSFET (7) supplies current to the other end (D) of the first secondary winding (5), the source electrodes of both MOSFETs (6, 7) are joined with a line (11), and by means of this line, with the other output (15) of the apparatus, and the two outputs (14, 15) of the apparatus are joined by means of a storage and smoothing capacitor (13), characterized by the fact that: the transformer (3) exhibits a second secondary winding (16) with ends (E, F), whereby the one end (E) exhibits the same polarity the as one end (C) of the first secondary winding (5); a control device (17) is present, which exhibits seven connections (21 through 27), whereby the first connection (21) is connected with the one end (E) of the second secondary winding (16), the second connection (22) with the second end (F), the third connection (23) is connected with the one end (C) of the first secondary winding (5), the fourth connection (24) is connected with the other end (D) of the first secondary winding (5), the fifth connection (25) is connected to the line (11), the sixth connection (26) to the gate electrode of the first MOSFET (6), and the seventh connection (27) to the gate electrode of the second MOSFET (7); and the control device (17) contains means for the determination of whether a voltage is being induced through the first and second secondary windings (5, 16), and based on that, whether the synchronous rectifier is working at all, and in the event of a negative case, additionally contains a means for blocking the two MOSFETs (6, 7), whereupon these MOSFETs can continue to carry out their diode function by means of their substrate diodes.
In another embodiment of the present invention, a synchrono
REFERENCES:
patent: 5343383 (1994-08-01), Shinada et al.
Allington Philip
Dittli Rene
Melcher AG
Riley Shawn
Wong Peter S.
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