Electricity: electrical systems and devices – Safety and protection of systems and devices – Voltage regulator protective circuits
Patent
1997-04-23
1999-05-11
Gaffin, Jeffrey A.
Electricity: electrical systems and devices
Safety and protection of systems and devices
Voltage regulator protective circuits
361 87, 361101, 323277, 363 75, H02H7/00
Patent
active
059034173
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
This invention relates to a self-excitation type switch power supply unit with a function of overcurrent protection.
TECHNICAL BACKGROUND
The self-excitation type switch power supply is a self-excited oscillator as to substance, which can be taken as a high-frequency heating means when output directly from a self-excited oscillation coil and as a DC power supply unit when rectified and output from a rectifier. The self-excitation type switch power supply has the advantages of simple circuitry, small size and lost cost, etc., but owing to lack of a simple and effective method for overcurrent protection, its stability and reliability are poor, which makes the self-excitation type switch power supply unable to become a reliable and practical power supply unit.
FIG. 1 is a block diagram of a general self-excitation type switch power supply unit comprising: a power source 1, an amplifier 2, a self-excited oscillation coil 3 and a positive feedback coupling circuit 5. The self-excited oscillation coil 3 comprises a master oscillation coil La, a positive feedback coil Lb and an output coil Lc.
DISCLOSURE OF THE INVENTION
The object of this invention is to provide a self-excitation type switch power supply unit with overcurrent protection, which can simply and effectively overcome the defects of poor stability and reliability of the existing self-excitation type switch power supply.
The object of this invention is fulfilled like this. FIG. 2 is a block diagram of the self-excitation type switch power supply unit to which this invention pertains, besides having the basic structure of FIG. 1, it is characterized in that a current negative feedback impedance 4 which can provide a DC path and contains a series resistance component is connected to the input and output common terminal A of the amplifier 2, the product of the impedance value of said current negative feedback impedance 4 and the predetermined current value of the overcurrent protection point is close to the positive feedback voltage on the positive feedback coil Lb in the self-excited oscillation coil 3. For certain reasons, the increase in the current 10 of the amplifier 2 exceeds the predetermined current value, the negative feedback voltage N on the current negative feedback impedance 4 increases accordingly until it is close to the positive feedback voltage P on the positive feedback coil Lb, for deficiency in the amount of the positive feedback, the oscillation circuit has to stop oscillation to fulfill the object of overcurrent protection.
This invention is only to add and connect the current negative feedback impedance to the input and output common terminal of the amplifier in the existing unit, the problem of overcurrent protection is entirely solved on the basis of that the cost and complication of the unit are almost not increased.
DESCRIPTION OF THE FIGURES
The following are descriptions on the figures and further descriptions are made on the detailed structures and the operation condition of this invention by combination with the embodiments.
FIG. 1 is a block diagram of a general self-excitation type switch power supply unit;
FIG. 2 is a block diagram of a self-excitation type switch power supply unit of this invention;
FIG. 3 is a circuitry schematic diagram of one embodiment of the self-excitation type switch power supply unit of this invention;
FIG. 4 is a circuitry schematic diagram of another embodiment of the self-excitation type switch power supply unit of this invention;
BEST MODE FOR FULFILLING THIS INVENTION
Refer to FIG. 3, in which a switch power supply unit constituted according to this invention is shown, said unit comprises: a power source 1, an amplifier 2, a self-excited oscillation coil 3, a current negative feedback impedance 4, a positive feedback coupling circuit 5, an oscillation-starting circuit 6 and a secondary rectification circuit 7.
110 V AC power supply is taken as a power source 1 after rectified and filtered. The amplifier 2 uses a pair of complementary amplifiers, which are compose
REFERENCES:
patent: 4236187 (1980-11-01), Mochizuki et al.
patent: 4323961 (1982-04-01), Josephson
patent: 5568343 (1996-10-01), Kosugi
Gaffin Jeffrey A.
Sherry Michael J.
LandOfFree
Self-excitation type switch power supply unit with overcurrent p does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Self-excitation type switch power supply unit with overcurrent p, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Self-excitation type switch power supply unit with overcurrent p will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-249934