Electrical transmission or interconnection systems – Switching systems – Switch actuation
Reexamination Certificate
2000-10-06
2003-01-07
Jackson, Stephen W. (Department: 2836)
Electrical transmission or interconnection systems
Switching systems
Switch actuation
C307S064000, C307S066000, C307S125000, C307S126000, C307S139000
Reexamination Certificate
active
06504270
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to an uninterruptible switching regulator in which an AC-side RCC (Ringing Choke Converter) type switching circuit drives a secondary drive circuit for driving a load such as a computer board when the commercial AC power supply is operating normally, and in the event of an unexpected situation such as a power outage, the system is automatically switched over so that the secondary drive circuit is instead driven by a DC-side RCC (Ringing Choke Converter) type switching circuit, and more particularly relates to an uninterruptible switching regulator configured such that an iron core and a magnetic path is shared by the AC-side RCC type switching circuit, the DC-side RCC type switching circuit, and the secondary drive circuit that connect a high-frequency transformer, the result of which is that a switching operation is performed between the switching element on the primary side and the switching element on the tertiary side in the supply of DC output to the secondary drive circuit. The present invention further relates to an uninterruptible switching regulator for a wide variety of computer applications; for instance, it can be used with a commercial AC power supply alone, it can be used with an external DC power supply alone, it can be used for automotive applications, and it affords uninterrupted operation through the double input of a commercial AC power supply and an external DC power supply.
2. Description of the Related Art
In Windows 95, 98, and NT, Linux, and other such operating systems used in personal computers, if the AC input power supply is accidentally turned off all of a sudden or if a power outage occurs during OS operation, for example, a memory failure can occur on the hard disk or, in a worst case, the OS can be damaged, requiring professional help for restarting the computer, and there has been a tremendous need in recent years for a way to deal with this situation.
FIG. 13
illustrates a common approach to this problem, in which a UPS (Uninterruptible Power Supply) is connected to the computer in series, ahead of the internal AC/DC switching power supply. Still, cost concerns often dictate the use of an inexpensive UPS, and because a device with low reliability is serially connected between the computer and the commercial power supply, there is actually an attendant drawback of lower reliability, extra space is required, and the cost is also proportionately higher.
FIG. 14
illustrates another method, which is often used on the existing internal switching power supply side. This is often used as a POS (Point Of Sale) system in which the commercial AC power supply is used to charge a battery that works by floating operation with an AC/DC switching power supply, and a DC/DC converter with multiple outputs put together into an integral structure on this load side is used as an internal uninterruptible switching regulator. Demand for this has been on the rise of late, as personal computers are increasingly used for POS systems. As another application, this system is also frequently used as an electronic switching device in PBX apparatus, and as personal computers make inroads in this area as well, uninterruptible switching regulators are again being used.
An advantage to the system shown in
FIG. 14
is that the circuit is simple, but drawbacks are poor efficiency (50 to 55%), larger size, higher cost, and greater energy consumption, which is a problem from a societal and environmental standpoint.
Poor efficiency is due to the fact that the AC/DC conversion switching power supply and the DC/DC converter are connected in series, so the overall efficiency is the product of multiplying the efficiency of the various power supplies.
For instance, when an AC/DC conversion switching power supply with an efficiency of 70% is connected in series with a DC/DC converter with an efficiency of 80%, multiplying the numerical values of the efficiency of the two produces an efficiency of 56%, and a drawback is that the apparatus must be larger in order to obtain a large output.
Another major drawback is that because the battery is connected to the ground terminal of the computer board that is the load, maintenance, it is difficult to facilitate maintenance, including battery management by providing the batteries of a plurality of computers separately outside and in common. Also, the present inventors have already commercialized an uninterruptible switching power supply of medium capacity (150 to 400 W), but when a small-capacity supply (40 to 100 W class) is produced with this medium capacity system, called a separately excited forward converter, the circuit becomes more complicated and there are more parts, which makes it difficult to keep the size compact and the cost low.
As personal computers have become smaller and lower in capacity in recent years, micro-ATX specifications, SFX specifications, and same-device power supply specifications with panel computers and the like have been published, and there is a need for smaller packages. A continuous output of approximately 100 W must be obtainable with a case size of 100 mm in width, 63.5 mm in height (thickness), and 125 mm in depth, and among multiple outputs, low voltage outputs of 5 V and 3.3 V require a capacity of 70 to 80 W, but since the efficiency of an ordinary RCC type switching power supply is only about 60%, 40 to 50 W is generally the limit with a low voltage output.
SUMMARY OF THE INVENTION
In light of the above, it is an object of the present invention to provide an uninterruptible switching regulator with which smaller size and lower cost can be achieved while the power supply efficiency is raised, which is accomplished by the effective utilization of an RCC type switching circuit.
In order to achieve the stated object, the uninterruptible switching regulator of the present invention is such that an AC-side RCC type switching circuit equipped with a switching element, which rectifies and converts into DC an AC voltage from a commercial AC power supply serving as the input source and then operates using the smoothed DC voltage as its input, is connected to the primary winding of a high-frequency transformer, there is provided an input voltage detection circuit that detects when the input voltage from the commercial AC power supply to the AC-side RCC type switching circuit drops below a set voltage, a secondary drive circuit for driving a load such as a computer board is connected to the secondary winding of the high-frequency transformer, a DC-side RCC type switching circuit equipped with a switching element, which is completely electrically insulated from the AC-side RCC type switching circuit and the secondary drive circuit and operates using a battery, an external DC power supply, or the like as its input source, is connected to the tertiary winding of the high-frequency transformer, there is provided high-speed switching means for switching at high speed the operation of the AC-side RCC type switching circuit and the DC-side RCC type switching circuit on the basis of the detection information from the input voltage detection circuit, when the input voltage detection circuit detects that the input voltage from the commercial AC power supply is at or above the set voltage, the operation of the DC-side RCC type switching circuit is halted and power is supplied to the secondary drive circuit by preferentially operating the AC-side RCC type switching circuit with an output command from the input voltage detection circuit, and when the input voltage detection circuit detects that the input voltage from the commercial AC power supply has dropped below the set voltage, power is supplied to the secondary drive circuit by operating the DC-side RCC type switching circuit and halting the operation of the AC-side RCC type switching circuit with an inverse output command from the input voltage detection circuit.
To obtain an output of, say, about 100 W, which is required for a micro-ATX power supply size of determined case size of 100
Armstrong Westerman & Hattori, LLP
Deberadinis Robert L.
Jackson Stephen W.
Nihon Protector Co., Ltd.
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