JP2000166236A - Power supply - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a power supply with the power supply efficiency in power saving operation taken into account. SOLUTION: The power supply 8 receives a power saving operation signal P1 from a host system, reduces its output V1 through a secondary control circuit 5 to shift to power saving operation, and supplies power to a primary control circuit 3 from the second auxiliary winding N2 of a switching transformer T1, thereby sustaining power saving operation. The reduction in output V1 or reduction of the auxiliary winding N2 is detected through a switching circuit 7 and a resonance capacitor C3 is disconnected during power saving operation. As a result, input power is reduced both during normal operation and during power saving operation and thus optimal power supply efficiency is obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD The present invention relates to a power supply device,
In particular, it relates to a power supply device provided with power saving means.

[0002]

2. Description of the Related Art As shown in FIG.
Rectification and smoothing circuit 1 for rectifying and smoothing AC input voltage
And the switching element 2 and the primary control circuit 3 for feeding back and stabilizing the output voltage of the secondary side rectification and smoothing circuit 4 from the secondary control circuit 5 to the primary side through the photocoupler PC1, and stabilizing the secondary side output voltage. A secondary control circuit 5 for performing a power-saving operation in response to a power-saving operation signal P1 from a host system, a first auxiliary winding N1 for supplying power to the primary control circuit 3, and a primary winding during the power-saving operation. A switching transformer T1 including a second auxiliary winding N2 for supplying power to the control circuit 3, and rectifying and smoothing the primary output voltage of the switching transformer T1 by diodes D1 and D2 and capacitors C1 and C2 to stabilize the output voltage; Circuit 6 for supplying the converted power to primary control circuit 3, and resonance capacitor C3 for setting the resonance frequency of switching element 2.
It is composed of

The operation of this conventional power supply device is such that, in the case of steady operation, a resonance capacitor C3 and a switching transformer T1 are used.
When the switching frequency at the time of turning on the switching element 2 is reduced by the resonance frequency determined by the inductance of the primary winding and the operation shifts to the power saving operation, the secondary control circuit receives the power saving operation signal P1 from the host system. 5
Reduces the output voltage V1 to V2, and supplies the power to the primary control circuit 3 as the output voltage V1 decreases. The output voltage of the first auxiliary winding N1 of the switching transformer T1 also decreases. 6 operates so as to supply power to the primary control circuit 3 from the second auxiliary winding N2 of the switching transformer T1, thereby maintaining the power saving operation.

Therefore, the resonance capacitor C during power saving operation
Since the discharge current flows through the switching element 2 due to the capacitance of 3, the switching loss of the switching element 2 is large, and the power supply efficiency is reduced.

[0005]

In this conventional power supply device, the power supply efficiency is reduced during the power saving operation, so that the equipment having a large output power on the secondary side can satisfy the input power regulation for the power saving operation. There was a problem that it was difficult.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a power supply device for reducing input power by separating a resonance capacitor required only in a normal operation state during a power saving operation.

[0007]

In order to solve the above-mentioned problems, a power supply device according to the present invention comprises a rectifying and smoothing circuit for rectifying and smoothing an AC input voltage and outputting an output voltage, and a rectifying and smoothing circuit. A switching element for switching the output voltage output, a primary control circuit for controlling the switching element, a resonance capacitor for setting a resonance frequency of the switching element controlled by the primary control circuit, and power supply to the primary control circuit And a second auxiliary winding that supplies power to the primary control circuit by operating the switch element during a power saving operation based on a power saving operation signal from a host system. A secondary-side rectification and smoothing circuit for rectifying and smoothing the secondary-side output voltage of the switching transformer;
A secondary control circuit that stabilizes the secondary output voltage rectified and smoothed by the secondary rectification and smoothing circuit, and reduces and stabilizes the secondary output voltage by the power-saving operation signal. The secondary control circuit is characterized by comprising a switching circuit for disconnecting the resonance capacitor at the time of stabilization by the power saving operation signal.

[0008]

Next, a power supply device according to an embodiment of the present invention will be described with reference to the drawings.

FIG. 1 is a circuit diagram of a power supply device according to one embodiment of the present invention.

A power supply according to an embodiment of the present invention comprises:
As shown in FIG. 1, a rectifying and smoothing circuit 1 for rectifying and smoothing an AC input voltage to output an output voltage, a switching element 2 for switching an output voltage output from the rectifying and smoothing circuit 1, A primary control circuit 3 for controlling the element 2, a resonance capacitor C3 for setting a resonance frequency of the switching element 2 controlled by the primary control circuit 3, and a first auxiliary winding N1 for supplying power to the primary control circuit 3 And a second auxiliary winding N2 for operating the switch element 2 to supply power to the primary control circuit 3 during a power saving operation according to a power saving operation signal P1 from the host system.
, A secondary-side rectification and smoothing circuit 4 for rectifying and smoothing the secondary-side output voltages V1 and V2 of the switching transformer T1, and a rectification and smoothing operation performed by the secondary-side rectification and smoothing circuit 4. Secondary output voltage V
1, V2 is stabilized, and the power saving operation signal P1
A secondary control circuit 5 for reducing and stabilizing the secondary side output voltages V1 and V2, and a power saving operation signal P1
And a switching circuit 7 for disconnecting the connection of the resonance capacitor C3 at the time of stabilization.

Next, the operation of the power supply according to one embodiment of the present invention will be described with reference to the drawings.

As shown in FIG. 1, the operation of the power supply according to one embodiment of the present invention is such that, in the case of steady operation, switching is performed by a resonance frequency determined by the resonance capacitor C3 and the inductance of the primary winding of the switching transformer T1. In the case of switching to the power saving operation by reducing the switching loss at the time of turning on the element 2 and receiving the power saving control operation P1 from the host system, the secondary control circuit 5 reduces the output voltage V1 to V2 and outputs When the voltage V1 decreases, the output voltage of the first auxiliary winding N1 of the switching transformer T1 for supplying power to the primary control circuit 3 decreases. At this time, the drive circuit 6 switches the second auxiliary winding N2 of the switching transformer T1.
From the power supply to the primary control circuit 3 to maintain the power saving operation.

Therefore, when the apparatus shifts to the power saving operation, the output voltage of the second auxiliary winding N2 also decreases in proportion to the decrease of the output voltage of the first auxiliary winding N1 of the switching transformer T1, and The switching circuit 7 detects a drop in the output voltage of the second auxiliary winding N2 or a drop in the secondary output voltage V1, and disconnects the resonance capacitor C3.

[0014]

As described above, according to the power supply device of the present invention, the connection of the resonance capacitor is cut off during the normal operation and during the power saving operation, so that the input power can be reduced in any of the operating states to optimize the operation. There is an effect that a high power supply efficiency can be obtained.

[Brief description of the drawings]

FIG. 1 is a circuit diagram of a power supply device according to an embodiment of the present invention.

FIG. 2 is a circuit diagram of a conventional power supply device.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Rectification and smoothing circuit 2 Switching element 3 Primary control circuit 4 Secondary side rectification and smoothing circuit 5 Secondary control circuit 6 Drive circuit 7 Switching circuit 8 Power supply device C1, C2 capacitor C3 Resonant capacitor D1, D2 Diode N1 First auxiliary Winding N2 Second auxiliary winding P1 Power saving operation signal PC1 Photocoupler R1, R2, R3 Resistance T1 Switching transformer Tr1 Switching element V1, V2 Secondary side output ZD1 Constant voltage diode

Claims (1)

[Claims] 1. A rectifying and smoothing circuit for rectifying and smoothing an AC input voltage to output an output voltage, a switching element for switching an output voltage output from the rectifying and smoothing circuit, and a primary element for controlling the switching element. A control circuit, a resonance capacitor for setting a resonance frequency of a switching element controlled by the primary control circuit, a first auxiliary winding for supplying power to the primary control circuit, and a power saving operation signal from a host system. A switching transformer having a second auxiliary winding that supplies power to the primary control circuit by operating the switch element during power saving operation, and a secondary side that rectifies and smoothes a secondary output voltage of the switching transformer. Rectifying and smoothing circuit, and stabilizing the secondary-side output voltage rectified and smoothed by the secondary-side rectifying and smoothing circuit, and A secondary control circuit that lowers and stabilizes the secondary output voltage by a power-saving operation signal, and a switching circuit that disconnects the resonance capacitor when the secondary control circuit is stabilized by the power-saving operation signal. A power supply device comprising: