Computer-controlled uninterruptible power supply

• US 5,184,025 A
• Filed: 10/01/1991
• Issued: 02/02/1993
• Est. Priority Date: 11/14/1988
• Status: Expired due to Fees

• Current Assignee: Elegant Design Solutions Incorporated
• Original Assignee: Elegant Design Solutions Incorporated
• Inventors: Hocker, Robert A., Ellison, George A., McCurry, Patrick W., Boekelheide, Karl, Sexton, Kenneth D., Kellogg, James R.
• Primary Examiner(s): Voeltz, Emanuel T.
• Application Number:
  US07/771,781
• Time in Patent Office: 490 Days
• Field of Search: 363/19-21, 363/24-26, 363/65, 363/89, 363/97, 363/41, 323/282, 323/284, 323/285, 323/354, 323/267, 307/48, 307/64-66, 307/80-81, 307/85-86, 364/431.11
• US Class Current: 307/66
• CPC Class Codes: G06F 1/28 Supervision thereof, e.g. detecting power-supply failure by out of limits supervision
• CPC Class Codes: H02J 9/061 for DC powered loads

Abstract

A computer-controlled, uninterruptible power supply system is disclosed. The system selectively operates from more than one input source of power, e.g. an AC line input, an external DC input and internal batteries. The system is of the type which utilizes one or more switch mode converters and is well suited for use in computer systems. The switch mode regulator has a PWM clock signal and provides a PWM drive signal. The PWM clock signal frequency is substantially greater than the PWM drive signal frequency. Transferring between the DC power sources is done in a manner substantially transparent to the regulator and the load, generally as follows. A signal indicating a transfer to a selected one of the DC power sources is gated in response to the PWM clock signal to form a first logic signal that is synchronized to the PWM clock signal. The first logic signal is gated in response to the PWM drive signal so as to form a second logic signal that is further synchronized to the PWM drive signal. Finally, the PWM drive signal is gated to a selected switching circuit responsive to the second logic signal, so that transfers between the DC power sources are fully synchronized to the PWM clock signal and to the PWM drive signal.

Claims

1. A power supply system comprising:

DC input means for providing a DC power signal to the system;

means for rectifying an ac power signal, when one is supplied to said system, and providing a rectified signal;

first regulating means for regulating said rectified signal and providing a first regulated DC signal, said first regulating means including a first switch mode regulator;

second regulating means for regulating a DC signal and providing a second regulated DC signal, said second regulating means including a second switch mode regulator having a switching frequency;

control means for causing either said DC power signal or said first regulated signal, when both said DC power signal and said AC power signal are supplied and one of them when only one of them is supplied, to be coupled to the second regulating means;

said control means being settable to cause a preselected one of said DC power signal and said first regulated signal to be coupled to said second regulating means when both said DC power signal and said AC power signal are supplied.

2. In a power supply system having first and second DC power sources and a switch mode regulator circuit to provide regulated DC power to a load, the switch mode regulator having a PWM clock signal and providing a PWM drive signal, the PWM clock signal having a frequency substantially greater than the PWM drive signal frequency, a method of transferring between the DC power sources that is substantially transparent to the regulator and the load, comprising the steps of:

providing a signal indicating a transfer to a selected one of the DC power sources;

gating the indicating signal responsive to the PWM clock signal so as to form a first logic signal that is synchronized to the PWM clock signal;

gating the first logic signal responsive to the PWM drive signal so as to form a second logic signal that is further synchronized to the PWM drive signal;

providing first and second switching circuits coupled between the first and second DC power sources and the load, respectively; and

gating the PWM drive signal to one of the switching circuits corresponding to the selected DC power source responsive to the second logic signal, so that transfers between the DC power sources are fully synchronized to the PWM clock signal and to the PWM drive signal.

3. A power supply system according to claim 2 wherein said gating the indicating signal includes:

providing a transfer logic signal responsive to the indicating signal;

providing a first flip-flop circuit coupled to receive the transfer logic signal; and

clocking the first flip-flop circuit with the PWM clock signal so that the first flip-flop output provides the first logic signal.

4. A power supply according to claim 3 wherein said gating the first logic signal includes:

providing a second flip-flop circuit coupled to receive the first logic signal; and

clocking the second flip-flop circuit with the PWM clock signal so that the second flip-flop output provides the second logic signal.