Dual/multiple voltage level input switching power supply

• US 5,751,564 A
• Filed: 08/10/1994
• Issued: 05/12/1998
• Est. Priority Date: 08/10/1994
• Status: Expired due to Fees

• Current Assignee: Ghing-Hsin Dien
• Original Assignee: Ghing-Hsin Dien
• Inventors: Dien, Ghing-Hsin
• Primary Examiner(s): NGUYEN, MATTHEW VAN
• Application Number:
  US08/292,815
• Time in Patent Office: 1,371 Days
• Field of Search: 363/34, 363/37, 307/22, 307/26, 307/28, 307/29, 307/64, 307/66, 307/75
• US Class Current: 363/37
• CPC Class Codes: H02J 9/062 for AC powered loads
• CPC Class Codes: H02M 1/10 Arrangements incorporating converting means for enabling loads to be operated at will from different kinds of power supplies, e.g. from ac or dc

Abstract

A switching power supply system which is able to connect two or more different power sources with different voltage levels, and can provide uninterrupted power even when the primary power source is low or absent. The output voltage is much more steady than that in a conventional switching power supply and the efficiency loss is smaller as well. As a result, the backup supply time is longer than a conventional UPS system. Finally, when used in, for example, a notebook computer, there is no need to use an AC to DC adaptor when connecting to commercial AC power since the switching power supply can be directly connected to the commercial AC power for operation.

Claims

1. A switching power supply system comprising:

a rectifier circuit which rectifies a primary AC power source into a DC voltage;

said rectifier circuit being connected to a transformer circuit;

a secondary power source;

the transformer circuit has a first and a second power source input, the first power source input is connected to the primary power source through the rectifier circuit and the second power source input is connected to the secondary power source;

a first and second control input is connected to a first and second switching circuit, respectively, which control switching currents from the primary and secondary power sources to the transformer circuit;

an output of the transformer circuit is connected to a load and to a first and second pulse width modulator circuit as feedback control;

the first pulse width modulator circuit is connected to the transformer circuit and a first output of the first pulse width modulator circuit is connected to the first control input of the first switching circuit and a second output is connected to a monitor circuit, the output from the transformer circuit is used as a feedback control signal and an output pulse from the first output of the first pulse width modulator circuit controls the first switching circuit'"'"'s ON-OFF operation;

the second output of the first pulse width modulator circuit provides the monitor circuit a monitoring signal of the operation condition of the first switching circuit sourced by the primary power source;

the second pulse width modulator circuit is connected to the transformer circuit and the monitor circuit and an output of the second pulse width modulator circuit is connected to the second control input of the second switching circuit, the output voltage from the transformer circuit is used as a feedback control signal and an output pulse from the second pulse width modulator circuit controls the second switching circuit'"'"'s ON-OFF operation;

an output from the monitor circuit controls the second pulse width modulator circuit according to the supply condition of the primary power source;

the first switching circuit is connected to the first pulse width modulator circuit mentioned above and the transformer circuit;

the first switching circuit'"'"'s ON-OFF operation is controlled by the first pulse width modulator circuit and will control the switching current in the transformer circuit sourced by the primary power source;

the second switching circuit is connected to the second pulse width modulator circuit mentioned above and the transformer circuit;

the second switching circuit'"'"'s ON-OFF operation is controlled by the second pulse width modulator circuit and will control the switching current in the transformer circuit sourced by the secondary power source;

the monitor circuit is connected to the rectifier circuit and the first pulse width modulator circuit, and the output from the monitor circuit is connected to the second pulse width modulator circuit;

voltages from the rectifier circuit and the first pulse width modulator circuit will be monitored in the monitor circuit and if a power failure is detected, the monitor circuit will enable the second switching circuit to bring the second power source on line.

2. A switching power supply system comprising:

a rectifier circuit which rectifies a primary AC power source into a DC voltage and is connected to a transformer circuit;

a secondary power source;

the transformer circuit has a first and a second power input, the first power input is connected to the primary power source through the rectifier circuit, and the second power input is connected to the secondary power source through a current switch;

a control input is connected to a switching circuit;

the switching circuit controls the switching currents from the primary and secondary power sources to the transformer circuit;

an output of the transformer circuit is connected to a load and to a pulse width modulator circuit as a feedback control;

the pulse width modulator circuit, is also connected to both the control input of the switching circuit and a monitor circuit;

the output from the transformer circuit is used as a feedback control signal and an output pulse from the pulse width modulator circuit to the control input of the switching circuit controls the ON-OFF operation of the switching circuit;

an output to the monitor circuit provides a signal of the operating condition of the switching circuit;

the switching circuit is connected to the pulse width modulator circuit and the transformer circuit;

the switching circuit'"'"'s ON-OFF operation is controlled by the pulse width modulator circuit and the output from the pulse width modulator circuit controls the switching currents in the transformer circuit;

the monitor circuit is connected to the rectifier circuit and the pulse width modulator circuit, and an output is connected to the current switch for the secondary power source;

voltage signals from the rectifier and the pulse width modulator circuit will be monitored in the monitor circuit and if a low power situation is detected, the monitor circuit will turn on the current switch to bring the secondary power supply on line.

3. A switching power supply system comprising:

(a) a transformer circuit, said transformer circuit comprising a first input for connection to a primary power source and second input for connection to a secondary power source;

(b) a power supply output to be connected to a load;

(c) means for regulating said power supply output;

(d) means for sensing an interruption wherein said interruption is selected from the group comprising;

said primary power source falling below a first predetermined voltage, said power supply output falling below a second predetermined voltage, and said primary power source approaching an overload condition; and

(e) means for utilizing said secondary power source when said interruption is sensed and, wherein said means for regulating said power supply output, said means for sensing an interruption, and said means for utilizing said secondary power source when said interruption is sensed comprises;

(i) a first switching circuit controlling a current flow from said primary power source through said first input of said transformer circuit;

(ii) a first pulse width modulator circuit regulating said power supply output by controlling the on and off operation of said first switching circuit;

(iii) a second switching circuit controlling a current flow from said secondary power source through said second input of said transformer circuit;

(iv) a second pulse width modulator circuit regulating said power supply output by controlling the on and off operation of said second switching circuit; and

(v) a monitor circuit monitoring a voltage from said first input and monitoring a voltage from said first pulse width modulator circuit, said monitor circuit comparing both said voltage from said first input and said voltage from said first pulse width modulator circuit to a reference voltage, and said monitor circuit enabling said second pulse width modulator circuit when said voltage from said first input and said voltage from said first pulse width modulator circuit are below said reference voltage.

4. A switching power supply system comprising:

(a) a transformer circuit, said transformer circuit comprising a first input for connection to a primary power source and a second input for connection to a secondary power source;

(b) a power supply output to be connected to a load;

(c) means for regulating said power supply output;

(d) means for sensing an interruption, wherein said interruption is selected from the group comprising;

said primary power source falling below a first predetermined voltage, said power supply output falling below a second predetermined voltage, and said primary power source approaching an overload condition; and

(e) means for utilizing said secondary power source when said interruption is sensed, and wherein said means for regulating said power supply output, said means for sensing an interruption, and said means for utilizing said secondary power source when said interruption is sensed comprises;

(i) a switching circuit controlling the current flow from both said primary and said secondary power sources through said transformer circuit;

(ii) a pulse width modulator circuit regulating said power supply output by controlling the on and off operation of said switching circuit;

(iii) a switch being located between said secondary power source and said second input of said transformer circuit, said switch being closed when an interrupt is sensed; and

(iv) a monitor circuit monitoring a voltage from said first input and monitoring a voltage from said pulse width modulator circuit, said monitor circuit comparing both said voltage from said first input and said voltage from said pulse width modulator circuit to a reference voltage, and said monitor circuit closing said switch when said voltage from said first input and said voltage from said pulse width modulator circuit are below said reference voltage.