POWER SUPPLY OVER VOLTAGE PROTECTION SYSTEM

• US 3,796,919 A
• Filed: 05/14/1973
• Issued: 03/12/1974
• Est. Priority Date: 05/14/1973
• Status: Expired due to Term

• Current Assignee: Miles Carrington Johnson
• Original Assignee: Miles Carrington Johnson
• Inventors: Johnson, Miles Carrington
• Primary Examiner(s): Miller, J. D.
• Assistant Examiner(s): Fendelman, Harvey
• Application Number:
  US05/359,903
• Time in Patent Office: 302 Days
• Field of Search: 323/8,20,4 317/31,16,33VR,27R
• US Class Current: 361/79
• CPC Class Codes: G05F 1/59 including plural semiconductor devices as final control devices for a single load
• CPC Class Codes: H02H 3/202 for dc systems
• CPC Class Codes: H02H 9/04 responsive to excess voltage lightning arrestors H01C7/12, H01C8/04, H01G9/18, H01T

Abstract

A power supply system is disclosed having a plurality of voltage regulator circuits connected in parallel with each other between a source of unregulated voltage and a load. Each of the voltage regulators includes an over voltage protection circuit whereby a particular regulator is taken out of service when the current in that regulator exceeds a certain level and the voltage across the load is at a first level. The regulator is not taken out of service when the current through the regulator is below the certain level and the voltage across the load is above the first level but below a second, higher, level.

Claims

1. In a power supply system comprising a plurality of voltage regulator circuits connected in parallel with each other, each of said voltage regulator circuits comprising a regulator means and a feedback control loop adapted for connection between a source of unregulated voltage and a load, each of said voltage regulator circuits further having an over voltage protection circuit comprising:

an output current sensor for providing a first signal when the current provided to said load exceeds a certain level;

an internal over voltage sensor for providing a second signal when the voltage across said load exceeds a first level;

an external over voltage sensor for providing a third signal when the voltage across said load exceeds a second level;

means responsive to said first, second and third signals for shutting down said regulator means in the presence of said first and second signals or in the presence of said third signal, and for maintaining said regulator means operative in the presence of only said second signal or in the presence of only said first signal.

2. The system according to claim 1 wherein said second voltage level is greater than said first voltage level.

3. The system according to claim 2 wherein said over voltage protection circuit further comprises a crowbar circuit means connected across said load and responsive to said third signal for providing a conductive path shunting said load when the voltage across said load exceeds said second level.

4. The system according to claim 3 wherein said means responsive to said first, second and third signals comprises a logic circuit having first and second OR circuits coupled through an AND circuit, said logic circuit having input terminals connected to said output current sensor, said internal over voltage sensor and said external over voltage sensor and an output terminal connected to said feedback control loop.

5. A power supply system comprising a plurality of voltage regulator circuits connected in parallel with each other, the parallel combination being adapted for connection between a source of unregulated voltage and a load, each one of said regulator circuits comprising:

a regulator means connected between said source of unregulated voltage and said load, an analog signal control loop connected between said load and said regulator means for controlling the conduction of current through said regulator means;

an over voltage control loop for providing a digital signal to said analog control loop in response to a certain current level supplied to said load and a first voltage level appearing across said load;

said analog control loop rendering said regulator means non-conductive in response to said digital signal;

said over voltage control loop further providing another digital signal to said analog control loOp when the voltage appearing across said load is at a second level;

said analog control loop rendering said regulator means non-conductive in response to said other digital signal.

6. The system according to claim 5 wherein said second voltage level is greater than said first voltage level.

7. The system according to claim 6 further comprising a crowbar circuit means located in each of said voltage regulator circuits, connected across said load, and responsive to said second voltage level for providing a conductive path shunting said load.