Battery backup system for switched power supply

• US 4,672,228 A
• Filed: 09/03/1985
• Issued: 06/09/1987
• Est. Priority Date: 09/03/1985
• Status: Expired due to Term

• Current Assignee: Pioneer Magnetics Incorporated
• Original Assignee: Pioneer Magnetics Incorporated
• Inventors: Swoboda, Jack W.
• Primary Examiner(s): Shoop, Jr., William M.
• Assistant Examiner(s): Ip, Shik Luen Paul
• Application Number:
  US06/772,134
• Time in Patent Office: 644 Days
• Field of Search: 307/64, 307/66, 320/40, 320/43, 361/90, 361/91, 361/92, 361/93
• US Class Current: 307/66
• CPC Class Codes: H02J 9/061 for DC powered loads

Abstract

A battery back-up system providing a short term hold-up for a converter type switched power supply. The back-up system includes a regulated charger circuit for maintaining the battery in a charged condition and a direct current fan which cools the power supply in both the normal and battery back-up modes. Over-voltage protection for the system is provided during the battery back-up mode, and protection for the battery is provided against excessive battery charging voltages. The fan and regulator are automatically turned off when the battery reaches a deep discharge condition to protect the battery.

Claims

1. A battery back-up system for an alternating current powered switched power supply, said power supply producing a direct current output, said power supply including a voltage regulator circuit, and said battery back-up system serving to maintain the direct current output from said power supply in the event of an alternating current power interruption, said back-up system including:

a battery;

terminal means connected to said battery;

a battery charging circuit;

first circuit means connecting the input of said charging circuit to said power supply for causing said power supply to energize said charging circuit during normal operation of the power supply, second circuit means connecting the output of said battery charging circuit to said terminal means for supplying a charging current to said battery during normal operation of the power supply;

third circuit means connecting the battery to the input of said voltage regulator circuit, said third circuit means including blocking means for causing the battery to supply power to the input of the voltage regulator circuit only when the voltage of the power supply drops below a predetermined level;

a fan for cooling the power supply;

circuitry connecting the fan to the output of the battery charging system to energize the fan during normal operation of the power supply and connecting the fan to the terminal means to energize the fan from the battery during alternating current power interruptions; and

an under-voltage detector connected to the terminal means for disconnecting the fan during alternating current power interruptions but only when the battery voltage drops below a particular minimum threshold.

2. The system defined in claim 1, in which said under-voltage detector includes circuitry for creating an hysteresis effect to prevent re-activation of the fan in the presence of transient voltage increases.

3. The system defined in claim 1, and which includes an under-voltage detector connected to said voltage regulator circuit for disabling said power supply during alternating current power interruptions, but only when the battery voltage drops below a particular minimum threshold.

4. The system defined in claim 3, in which said under-voltage detector includes circuitry for creating an hysteresis effect to prevent re-activation of said power supply in the presence of transient voltage increases.

5. The system defined in claim 1, and which includes an over-voltage detector connected to the output of said voltage regulator circuit for disconnecting the battery when the output voltage of said power supply exceeds a particular maximum threshold.

6. The system defined in claim 1, and which includes an over-voltage detector connected to the output of said battery charging circuit for disconnecting the battery when the output voltage of said battery charging circuit exceeds a particular maximum threshold.