Electric power conversion systems – Current conversion – Including d.c.-a.c.-d.c. converter
Reexamination Certificate
2000-01-19
2001-09-25
Riley, Shawn (Department: 2838)
Electric power conversion systems
Current conversion
Including d.c.-a.c.-d.c. converter
Reexamination Certificate
active
06295212
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates generally to power supply systems and, more particularly, to off-line power supplies for supplying a d-c. output from an a-c. power source. A particularly useful application for the present invention is in bias supplies and other cost-sensitive applications such as appliances using microprocessors.
SUMMARY OF THE INVENTION
U.S. Pat. No. 5,790,390 describes a power supply system that includes an a-c. power source and an off-line power supply for storing energy from the a-c. power source during first selected time intervals and converting at least a portion of the stored energy to a d-c. output during second selected time intervals. A diode or other switch disconnects the off-line power supply from the a-c. power source during the second selected time intervals to reduce conducted EMI. The first and second selected time intervals are preferably synchronized to the frequency of the a-c. power source.
It is a primary object of the present invention to provide an improved off-line power supply of the general type described in the aforementioned patent but having improved efficiency.
Another important object of this invention is to provide an improved off-line isolated power supply which provides constant d-c. output power over a wide a-c. input voltage and temperature range.
It is yet another object of this invention to provide such an improved off-line power supply which is extremely reliable in operation, and can be made with a rugged construction.
Other objects and advantages of the invention will be apparent from the following detailed description and the accompanying drawings. In accordance with the present invention, the foregoing objectives are realized by providing a power supply system comprising an a-c. power source; an off-line power supply for storing energy from the a-c. power source during first selected time intervals and converting at least a portion of the stored energy to a d-c. output during second selected time intervals; means for disconnecting the off-line power supply from the a-c. power source during the second selected time intervals to reduce conducted EMI; and power-regulation means for preventing variations in the first and second selected time intervals due to a-c. input voltage and temperature variations. In the preferred embodiment of the invention, the power-regulation means is effective at operating a-c. input voltages ranging from 85 to 265 and temperatures ranging from below zero degrees C. to above 75 degrees C.
The off-line power supply of this invention preferably includes switching means for controlling the first and second selected time intervals, and energy-conserving means for storing energy for triggering the switching means during the second selected time intervals so as to avoid continuous power consumption during those intervals.
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“Design Idea DI-3 TOPSwitch® Burst Mode Flyback” Power® Integrations, Inc. (two pages), Jun. 1998, source: www.powerint.com. No Author.
“Design Idea DI-1 TOPSwitch® Buck Converter” Power® Integrations, Inc. (two pages), Jun. 1998, source: www.powerint.com. No Author.
“TNY253/254/255 TinySwitch™ Family Energy Efficient, Low Power Off-line Switchers” Power® Integrations, Inc. (16 pages), Feb. 1999. No Author.
“TinySwitch™ Flyback Design Methodology Application Note AN-23” Power® Integrations, Inc. (10 pages), Jul. 1999. No Author.
“TNY256 TinySwitch™ Plus Engery Efficient, Low Power Off-line Switcher” Power® Integrations, Inc. (20 pages), Aug. 1999. No Author.
Kayser Kenneth W.
Shaufl Robert A.
Zsamboky Kalman
Bias Power Technology, Inc.
Jenkens & Gilchrist
Riley Shawn
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