Patent ID: 6664660
Filing Date: 2003-12-16
Classification: H02J,H02M

Abstract:
A parallel power supply system with an over-voltage protection circuit for providing a stable DC output voltage, comprising:a first power supply having a first output terminal for providing a first DC output voltage and a first ground terminal electrically connected to ground; a second power supply having a second output terminal for providing a second DC output voltage and a second ground terminal electrically connected to ground; a first diode having an anode end electrically connected to said first output terminal of said first power supply; a second diode having an anode end electrically connected to said second output terminal of said second power supply, and a cathode end electrically connected to a cathode end of said first diode for forming a node which is an output of said parallel power supply system; a first voltage feedback controller electrically connected to said first DC output voltage for providing a first control signal to control said first DC output voltage of said first power supply at a predetermined value; a second voltage feedback controller electrically connected to said second DC output voltage for providing a second control signal to control said second DC output voltage of said second power supply at said predetermined value; a first resistor having one end electrically connected to said node and the other end electrically connected to an input terminal of said first voltage feedback controller; a second resistor having one end electrically connected to said node and the other end electrically connected to an input terminal of said second voltage feedback controller; a third diode having an anode end electrically connected to said input terminal of said first voltage feedback controller and a cathode end electrically connected to said first output terminal of said first power supply; and a fourth diode having an anode end electrically connected to said input terminal of said second voltage feedback controller and a cathode end electrically connected to said second output terminal of said first power supply, wherein said first DC output voltage turns on said fourth diode for maintaining said DC output voltage of said parallel power supply system at said predetermined value when said first DC output voltage is greater than said predetermined value, and said second DC output voltage turns on said third diode for maintaining said DC output voltage of said parallel power supply system at said predetermined value when said second DC output voltage is greater than said predetermined value.