Electric power conversion systems – Current conversion – With means to introduce or eliminate frequency components
Reexamination Certificate
2002-11-18
2004-11-02
Vu, Bao Q. (Department: 2838)
Electric power conversion systems
Current conversion
With means to introduce or eliminate frequency components
C363S039000
Reexamination Certificate
active
06813168
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates generally to power supplies and, more specifically, the present invention relates to a switched mode power supply with an input electromagnetic interference (EMI) filter circuit.
2. Background Information
Electronic devices use power to operate. Switched mode power supplies or adapters are widely used to power electronic products as well as charge batteries used to power mobile products such as for example wireless phones, palm top computers, toys, etc. Switched mode power supplies generate EMI, which must be filtered to allow the power supply to meet national and international standards stipulating acceptable levels of EMI. This requires that the switched mode power supply include components at the input of the power supply that filter EMI in order to meet these standards. Furthermore, an input fuse is required to meet national and international safety standards.
Known power supply techniques employ input EMI filter circuits of varying complexity. The simplest form of input EMI filter is known as a pi filter and is used in low-power power supplies to reduce power supply cost. The fuse is a separate component, which is typically either designed solely for use as a fuse or as a resistor specifically designed to meet national and international safety standards as a fusible component.
SUMMARY OF THE INVENTION
A power supply input EMI filter circuit is disclosed. In one embodiment, a method of filtering EMI in a power supply includes rectifying an AC signal with a rectifier, smoothing the rectified signal with a bulk storage capacitor to provide a DC output as an input to a power conversion circuit and filtering the EMI generated by the power conversion circuit from reaching the AC source by using the bulk capacitor and one or more inductors in combination with the AC source capacitance as an EMI filter. In one embodiment the method also includes the use of one or more of the inductors as a fusing element to meet safety requirements. Additional features and benefits of the present invention will become apparent from the detailed description and figures set forth below.
REFERENCES:
patent: 3273044 (1966-09-01), Clarke
patent: 4222096 (1980-09-01), Capewell
patent: 5818705 (1998-10-01), Faulk
patent: 6400584 (2002-06-01), Sabate et al.
patent: 6594165 (2003-07-01), Duerbaum et al.
patent: 2002/0114176 (2002-08-01), Morita et al.
patent: 20119996 (2002-03-01), None
patent: 03257154 (2004-02-01), None
Power Integrations, Inc., “TNY 256 TinySwitch® Plus Energy Efficient, Low Power Off-line Switcher”, pp. 1-20, Jul. 2001.
Qu, Song et al., “Mixed-Mode EMI Noise and Its Implications to Filter Design in Offline Switching Power Supplies,”IEEE, 2000, pp. 707-713.
Caponet, Marco Chiado et al., “EMI Filters Design for Power Electronics,”IEEE, 2000, pp. 2027-2032.
Wang, Shuo et al., “Improving the Performance of Boost PFC EMI Filters,”IEEE, 2003, pp. 368-374.
Blakely , Sokoloff, Taylor & Zafman LLP
Power Integrations, Inc.
Vu Bao Q.
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