Title:
OVERCURRENT PROTECTING CIRCUIT OF CONSTANT-VOLTAGE ELECTRIC POWER SUPPLYING CIRCUIT
Document Type and Number:
Japanese Patent JPS58114212
Kind Code:
A
Abstract:
PURPOSE:To protect a circuit, by controlling an overcurrent protecting circuit by an output of a rectifier having no time constant circuit, and cutting off a current of a main transistor for a prescribed time, when a switching type constant- voltage electric power supplying circuit of a pulse width controlling system has become an overload. CONSTITUTION:DC obtained by rectifying an AC power supply 1 is converted to AC by switching-controlling TRs Q1-Q4 by a controlling circuit 4 consisting of a comparator 11 for shaping the pulse width, an FF13, NOR gates 14, 15, transistors TRQ5, Q6, and a transformer 16, is transformed by a transformer 5, is rectified 6, 7, and supplies DC constant-voltage to a load 9. When an overcurrent flows to the TRs Q1-Q4, it is detected by a current transformer 21, is rectified by a rectifier 22 having no time constant, is compared with a reference value by a comparator 25, sets an FF26, and is inputted to the comparator 11 through a TRQ7. By its output, the NOR gates 14, 15 are stopped, the TRs Q5. Q6 are turned off, and the TRs Q1-Q4 are stopped. A triangular wave of an OSC12 resets the FF26 by differentiating circuits 27, 29 and a monostable multivibrator 28 after a prescribed time has passed, and resets the supply voltage.
Inventors:
YAMASHITA SHIGEJI
YOSHIDA HARUNOBU
YOSHIDA HARUNOBU
Application Number:
JP21099881A
Publication Date:
July 07, 1983
Filing Date:
December 28, 1981
Export Citation:
Assignee:
FUJITSU DENSO
International Classes:
H02M3/335; H02H3/08; H02H7/12; H02M3/337; (IPC1-7): G05F1/64
Domestic Patent References:
| JPS5553183A | 1980-04-18 |
Attorney, Agent or Firm:
Koshiro Matsuoka