High efficiency AC/DC power supply
First Claim
1. A power supply for converting an AC supply to a DC output, said power supply comprising:
- a rectifier assembly connected to said AC supply, and providing a rectified current;
a first converter inputting said rectified current, and providing a first DC output current at a voltage substantially below that of said AC supply;
a second converter inputting said first DC output current, and providing a second DC output current; and
at least one capacitor disposed at the output of said first converter for reducing the voltage drop of said first DC output current during zero-crossing of said input AC supply,wherein the capacitance of said at least one capacitor is such that a major part of its stored energy is discharged during every half cycle of said AC supply.
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Accused Products
Abstract
A power supply for converting AC to a regulated DC output current, utilizing two serial switched mode power supplies, the first providing an intermediate DC output voltage with only moderate ripple properties, this output being input to the second, which operates as a DC/DC converter to provide the desired output with low ripple and good regulation. The diode rectifier assembly has no reservoir/smoothing capacitor, or one of much smaller capacitance than in prior art power supplies. The large resulting rectifier output ripple is overcome by use of the two power supply units, at least the first having a smoothing capacitor at its output. A majority of the energy stored in this capacitor is utilized during each AC half cycle. Such power supplies also provide improved hold-up times. The power supply is also constructed to have low standby power consumption, by use of a double burst configuration.
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Citations
34 Claims
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1. A power supply for converting an AC supply to a DC output, said power supply comprising:
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a rectifier assembly connected to said AC supply, and providing a rectified current; a first converter inputting said rectified current, and providing a first DC output current at a voltage substantially below that of said AC supply; a second converter inputting said first DC output current, and providing a second DC output current; and at least one capacitor disposed at the output of said first converter for reducing the voltage drop of said first DC output current during zero-crossing of said input AC supply, wherein the capacitance of said at least one capacitor is such that a major part of its stored energy is discharged during every half cycle of said AC supply. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17)
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18. A power supply comprising:
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at least first and second serially connected converters; a first at least one capacitor connected across the output of said first converter; a voltage detection element monitoring the voltage on said first at least one capacitor, causing said first converter to enter a sleep mode if said voltage on said first at least one capacitor exceeds a first predetermined level, and arousing said first converter from its sleep mode if said voltage on said first at least one capacitor falls below a second predetermined level; a second at least one capacitor connected across the output of said second converter; and a voltage detection element monitoring the voltage on said second at least one capacitor, causing said second converter to enter a sleep mode if said voltage on said second at least one capacitor exceeds a first preselected level, and arousing said second converter from its sleep mode if said voltage on said second at least one capacitor falls below a second preselected level. - View Dependent Claims (19, 20, 21, 22, 23, 24, 25, 26)
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27. A switched mode power supply comprising:
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an input for receiving a DC current; switching circuitry for generating a high frequency AC current from said input DC current; a high frequency transformer receiving said high-frequency AC current in a primary winding, said transformer having a secondary winding for outputting said high-frequency AC current at a desired voltage level; a rectifier unit for rectifying said transformed said high-frequency AC current to a DC output current; and an additional primary winding on said high-frequency transformer coupled magnetically to said secondary winding, wherein a signal injected onto said secondary winding induces into said additional primary winding a signal electrically isolated from said secondary winding, and usable for control functions in said switched mode power supply. - View Dependent Claims (28, 29, 30)
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31. A power supply for converting an AC supply to a DC output, said power supply comprising:
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a rectifier assembly connected to said AC supply, and providing a rectified current; a first converter inputting said rectified current, and providing a first DC output current at a voltage substantially below that of said AC supply; a second converter inputting said first DC output current, and providing a second DC output current; and at least one capacitor disposed at the output of said first converter for reducing voltage drop in said first DC output current, wherein the capacitance of said at least one capacitor is such that said voltage drop in said first DC output current is limited so that said power supply continues to provide a predetermined output power level for a predetermined time period following cessation of said AC supply. - View Dependent Claims (32, 33, 34)
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Specification