JP2007089377A - Fan less power supply - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a power supply with no fan motor by realizing high efficient power supply circuit, with no use of a smoothing capacitor, reducing loss due to a rush-in current preventing circuit, and with improved harmonics current by a one-converter system. <P>SOLUTION: The fan less power supply comprises a primary side circuit equipped with a rectifying circuit, a primary winding of a high frequency transformer, and a primary side switching element that is connected in series to the primary winding and controlled by the IC for coping with harmonics, with no smoothing capacitor included, and a secondary side circuit that supplies a DC output power to a load equipped with the secondary winding of the high frequency transformer and rectifying/smoothing circuits connected to the secondary winding. An output voltage along with an auxiliary voltage for controlling can be simultaneously taken out of one of the secondary windings. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

The present invention reduces the heat generation inside the power supply by reducing the number of parts and improving the efficiency of the power supply circuit in a computer ATX power supply that requires multiple outputs such as 5V standby output and -12V output. ATX power supplies for computers that are fanless, eliminating the need for fan motors, and are smaller, lighter, and less expensive by not using fan motors.

Computer ATX power supplies that are built into computer casings are generally equipped with cooling fan motors to release heat from circuit components inside the power supplies, and prevent damage to the power supply due to heat. Are known.

Although a power supply with a cooling fan motor can provide a cooling effect inside the power supply, the noise caused by the machine operation noise from the fan motor, the wind sucked by the fan motor and the wind noise caused by the power supply chassis, The life of electronic components is short compared to the life of electronic components, and the use of a fan motor, which is a mechanical component, reduces the durability of the entire power supply, and the fan motor attracts dust. ing.

In the present invention, loss can be reduced by the inrush current prevention circuit, harmonic current can be improved by the one-converter method, and high efficiency of the power supply circuit can be realized to suppress heat generation and eliminate the need for a fan motor. did.

According to the present invention, by eliminating the fan motor provided in the ATX power supply for computers, it is possible to realize not only miniaturization and weight reduction, low cost, but also noise reduction and improvement of power supply durability.

Furthermore, by making it possible to directly use a coarse output including ripples output to the secondary winding as a 24V output for a mechanism, a power supply for a computer having a mechanism output can be obtained.

A commercial AC power source as an input source is connected to a rectifier circuit through a filter circuit, and an output from the rectifier circuit is connected in series with a primary winding of a high-frequency transformer and a primary side switching element controlled by a PFC control circuit. Connect to form a primary circuit. A secondary winding and an auxiliary winding are provided on the secondary side of the high-frequency transformer. A chopper circuit is provided as a unit after the rectification / smoothing circuit in the secondary winding to control a plurality of necessary output voltages. On the other hand, an auxiliary voltage circuit for operating the secondary side control circuit is provided on the positive side of the auxiliary winding, and a circuit for outputting a negative voltage is connected to the negative side of the auxiliary winding. The secondary circuit is used.

A smoothing circuit that smoothes an AC voltage from a commercial AC power source that is an input is a smoothing circuit that does not include a smoothing capacitor made of a large-capacity electrolytic capacitor. By not including a smoothing capacitor on the primary side, the voltage rectified by the rectifier bridge is converted directly to the secondary side by a high-frequency transformer, so a smoothing capacitor is required on the secondary side. A resistor and thermistor can be used to prevent inrush current flowing through the smoothing capacitor by removing a large-capacity smoothing capacitor from the primary side. The inrush current prevention circuit made up of, etc. can be deleted at the same time. This not only reduces the number of components, but also eliminates the loss caused by the inrush current prevention circuit, leading to improved efficiency.

In an active filter circuit provided to take measures against harmonic currents of power supply devices, it is common to place a choke coil, rectifier diode, and capacitor for configuring the active filter circuit in the primary side circuit. As is well known, in the present invention, a high-frequency transformer that insulates the primary side and the secondary side has both a choke coil function and a voltage conversion function of the active filter circuit, and is necessary for the active filter circuit. As for the rectifier diode and the capacitor, the diode and the capacitor that perform rectification and smoothing on the secondary side are also used. As a result, not only can the size and weight be reduced by reducing the number of parts, but also the cost can be reduced, and the efficiency can be improved by reducing loss.

In a power supply circuit including an active filter circuit, two switching elements for a boost converter as an active filter circuit and a switching element for propagating power from a primary side to a secondary side of a high-frequency transformer as a power supply circuit In this method, when the active filter switching element is ON, a rectifier bridge, choke coil, active filter switching element, rectifier bridge from the commercial AC power source is used. , Current flows through the commercial AC power supply, and when the active filter switching element is OFF, the commercial AC power supply is connected to the rectifier bridge, choke coil, capacitor, rectifier bridge, commercial AC power supply, Current flows through the over.

In this way, in the method using two normal switching elements, current always flows when viewed from the commercial AC power source side as an input, whereas in the one converter method used in the present invention, The switching element is only connected to one end of the primary winding of the high-frequency transformer, and current flows only when the switching element is ON.

When the power circuit method is the flyback method, the energy propagated from the primary side to the secondary side via the high-frequency transformer is constant power, so constant power input is seen from the secondary side circuit. It is in the same state as In the case of constant power input, if the output voltage decreases due to overcurrent or short circuit, the output current will increase because the power is constant. It was a problem because there was a fear of damage. In order to solve this problem, the present invention provides a circuit that cuts off the flow of output current when it is detected that the main output voltage has dropped to a preset voltage (for example, 24V output and set voltage 16V). . By providing this circuit, even if the power supply is started with the secondary output kept short-circuited, this detection circuit works and the circuit is protected.

The ATX power supply for a computer of the present invention requires a -12V output. Therefore, not only the -12V output but also a circuit for generating an auxiliary voltage for operating the secondary side control circuit is arranged in the secondary winding that outputs -12V of the high-frequency transformer. The same winding is also provided with a circuit for detecting the above-described drop in output voltage. For this reason, the auxiliary voltage is made from a low-voltage circuit, thereby providing an efficient circuit configuration.

In an ATX power supply for a computer that requires multiple outputs such as 5V standby and -12V, an output including a ripple voltage that is only smoothed (for example, 24V output) is provided as an output voltage by a smoothing capacitor on the secondary side. In this way, it is possible to realize an ATX power supply for a computer that also has a mechanical output capable of allowing a ripple voltage.

FIG. 1 shows an embodiment of the present invention. The input voltage which is full-wave rectified by the rectifier bridge 3 through the noise filter 2 using the commercial AC power source 1 as an input source is switched by the switching element 5 and propagated to the secondary side. At this time, the active filter circuit composed of the control IC 4, the high frequency transformer 6, the rectifier diode 9, and the smoothing capacitor 10 as a countermeasure against the harmonic current causes the input current to have a sine wave shape similar to the input voltage, thereby suppressing the harmonic current. Is obtained.

Further, the primary side circuit does not require a smoothing capacitor, and a thermistor and a resistor constituting an inrush current preventing circuit for preventing an inrush current of the smoothing capacitor are also unnecessary. A one-converter system in which the switching element for the active filter circuit is also used as the switching element 5 for the power source is used to improve efficiency by allowing a current to flow only during the ON time of the switching element.

FIG. 2 shows that an auxiliary voltage and an output voltage can be obtained in the secondary winding N2 for obtaining a -12V output. An auxiliary voltage circuit is provided on the + side of the secondary winding N2, and a −12V output is produced on the − side. The secondary side output voltage (-12V in this case) is supplied with the energy when the primary side switching element is OFF, and the circuit provided on the opposite side of the same winding when ON is efficiently used from the low voltage circuit. The control circuit voltage is generated.

With the circuit configuration described above, the auxiliary voltage is generated from the main output by the chopper circuit, so that a circuit for generating the auxiliary voltage required for a normal computer ATX power supply and a transformer are not required, saving space and cost. The effect is obtained in the reduction.

Although the output voltage, for example, 24V output can be taken directly from the secondary winding in the first embodiment described above, it is a rough output voltage including a ripple voltage, but it can be used for mechanical applications. It is characterized by the configuration of a power supply device that has both a computer power supply and a mechanical power supply.

1 is a circuit block diagram illustrating an embodiment of the present invention. The figure which showed the voltage which occurs in secondary side winding N2 Circuits lock diagram representing an embodiment with 24V output for mechanical use

Explanation of symbols

1 Commercial AC Power Supply 2 Noise Filter 3 Rectifier Bridge 4 Harmonic Countermeasure IC
5 Switching element 6 High-frequency transformer 7 Rectifier diode 8 Rectifier diode 9 Rectifier diode 10 Smoothing capacitor 11 Smoothing capacitor

Claims (3)

A rectifier circuit that rectifies an AC voltage from an AC power source, a primary winding on the output side of the rectifier circuit that is connected in series to the primary winding and controlled by a harmonic countermeasure IC DC output power for a load having a primary circuit that does not include a smoothing capacitor, a secondary winding of the high-frequency transformer, and a rectifying and smoothing circuit connected to the secondary winding. A secondary side circuit for supplying the power, and a configuration in which an auxiliary voltage for control can be taken out simultaneously with the output voltage from one of the secondary windings, and the heat generation from the circuit components is reduced by increasing the efficiency of the circuit, ATX power supply for multi-output computers that does not require a cooling fan. 2. The computer ATX power supply device according to claim 1, wherein the computer ATX power supply is provided with a mechanical output by supplying power taken directly from the secondary winding as a mechanical output. 3. The ATX power supply device for a computer according to claim 1, wherein a smoothing capacitor is included in the primary side circuit.

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