JPH09140128A - Switching power supply apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a switching power supply apparatus having excellent characteristics which solve the problem of a conventional switching power supply apparatus employed in various electrical equipment, that is, the conversion efficiency of the apparatus is low at the time of operation waiting, i.e., at the time of a light load, and the total lifetime power consumption of the equipment is much larger than the actual power consumption, and with which the conversion efficiency at the time of operation waiting can be improved and the total lifetime power consumption of the equipment can be reduced. SOLUTION: A switching power supply apparatus has a microcomputer 8 which recognizes or controls the operation state of equipment and a transmission circuit 9 which transmits a control signal supplied by the microcomputer 8 to a primary side. The output of the transmission circuit 9 is supplied to a primary side switching device controller and the oscillation frequency of a switching power supply is controlled by the microcomputer. With this constitution, the switching power supply apparatus having excellent characteristics with which the conversion efficiency at the time of operation waiting can be improved and the total lifetime power consumption of the equipment can be reduced can be obtained.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a general household electric appliance, such as a VTR and a facsimile, which has an operation standby mode, is energized all day, and has a large power consumption difference between the normal operation mode and the operation standby mode. The present invention relates to an effective power supply device.

[0002]

2. Description of the Related Art In recent years, there are many home electric appliances which are controlled by a microcomputer, and in addition to the original operation, the usage for operating the operation under a certain condition has become common. Therefore, it is necessary to keep the power supply in the operation standby mode at all times, and a certain amount of power is consumed during that time. Moreover, in actuality, this operation standby mode occupies most of the usage time of the device. This power must be kept as low as possible from the viewpoint of energy saving.

A conventional switching power supply device will be described below. FIG. 2 shows a circuit configuration of a conventional switching power supply device. In FIG. 2, 1 is a transformer 6
Is a switching element that turns on / off the current flowing in the primary winding of the control terminal 1a, and turns on when the voltage of the control terminal 1a reaches the threshold voltage. Reference numeral 2 is a switch element drive circuit for turning on / off the switch element 1, 3 is a primary side switch element drive control circuit for controlling the on time of the switch element 1 and stabilizing the secondary side output voltage, 4 is a secondary side of the transformer 6. Secondary-side rectifying / smoothing circuit connected to the winding, 5 is a primary-side rectifying / smoothing circuit connected to the primary-side auxiliary winding of the transformer 6, and 6 is an electromagnetic wave that insulates the primary side from the secondary side. A transformer that converts the primary side input voltage into a secondary side required voltage by coupling, and 7 is a detection circuit that detects the secondary side output voltage output from the secondary side rectifying and smoothing circuit 4.

[0004] The operation of the conventional switching power supply device configured as described above will be described below.

First, when the device is in a normal operation state, the detection circuit 7 detects the output voltage of the secondary side rectifying and smoothing circuit 4, and the detection result is detected by the primary side switch element drive control circuit 3
Communicate to The primary side switch element drive control circuit 3 controls the switch element drive circuit 2 to determine the oscillation frequency, and the required load is supplied from the primary side to the secondary side via the transformer 6.

When the normal operation state of the equipment changes to the operation standby state, that is, when the secondary load shifts from large to small, the output voltage of the secondary side rectifying and smoothing circuit 4 rises, and this voltage rise is detected. 7 and transmits to the primary side switch element drive control circuit 3. The primary side switch element drive control circuit 3 controls the switch element drive circuit 2 and raises the oscillation frequency, so that the feedback loop operates to keep the output voltage constant.

[0007]

However, in the above-mentioned conventional structure, the oscillation frequency rises during the operation standby and the loss of the switch element 1 increases, so that the conversion efficiency during the operation standby, that is, the light load deteriorates. As a result, there has been a problem that the lifetime total power consumption of the device becomes large.

The present invention solves the above problems, and an object of the present invention is to provide a switching power supply device capable of improving the conversion efficiency of the switching power supply during operation standby and reducing the power consumption during operation standby. To do.

[0009]

To achieve this object, a switching power supply device of the present invention comprises a primary auxiliary winding electromagnetically coupled to a primary winding and a secondary winding for obtaining an output voltage. A transformer, a primary rectifying / smoothing circuit connected to the primary auxiliary winding of the transformer, a secondary rectifying / smoothing circuit connected to the secondary winding of the transformer, and a secondary side output voltage obtained from the rectifying / smoothing circuit. Detection circuit, a switching element that turns on / off the current flowing in the primary winding of the transformer and turns on when the control terminal voltage reaches the threshold voltage, and a switching element that turns the switching element on / off Stabilize the secondary side output voltage by controlling the on time of the switch element by the feedback signal from the drive circuit and the detection circuit 1
A micro switch that determines the operation mode of the secondary switch element drive control circuit and the equipment that uses this device, operates by the secondary output voltage obtained from the secondary rectification smoothing circuit, and outputs a pulse wave of a specific frequency in the operation standby mode. A computer,
And a transmission circuit for transmitting an output signal from the microcomputer to the primary side switch element drive control circuit.

With this configuration, it is possible to obtain the switching power supply device which can improve the conversion efficiency of the switching power supply during the operation standby and reduce the power consumption during the operation standby.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The inventions according to claims 1 and 2 of the present invention include a transformer having a primary auxiliary winding electromagnetically coupled to the primary winding and a secondary winding for obtaining an output voltage. A primary rectifying / smoothing circuit connected to the primary auxiliary winding of the transformer, a secondary rectifying / smoothing circuit connected to the secondary winding of the transformer, and a secondary side output voltage obtained from the rectifying / smoothing circuit. Detection circuit, a switch element that turns on / off the current flowing through the primary winding of the transformer and turns on when the control terminal voltage reaches the threshold voltage, and turns on / off the switch element. A switch element drive circuit, a primary side switch element drive control circuit that controls the on time of the switch element by a feedback signal from the detection circuit to stabilize the secondary side output voltage, and an operation mode of a device using this device. A microcomputer that operates by the secondary side output voltage obtained by the secondary rectifying and smoothing circuit and outputs a pulse wave of a specific frequency in the operation standby mode, and an output signal from the microcomputer for driving the primary side switch element. And a transmission circuit for transmitting to the control circuit.
Even if the load on the secondary side is extremely light as compared with the load during normal operation, the oscillation frequency of the switching power supply can be controlled by the microcomputer to operate at an efficient oscillation frequency.

Hereinafter, an embodiment of the present invention will be described with reference to FIG.
This will be described with reference to FIG. (Embodiment 1) FIG. 1 is a circuit diagram of a switching power supply according to the present invention. In FIG. 1, reference numeral 1 is a switch element for turning on / off a current flowing in a primary winding of a transformer. It is turned on when the threshold voltage is reached. 2 is a switch element drive circuit for turning on / off the switch element 1, 3 is a primary side switch element drive control circuit for stabilizing the secondary side output voltage, and 4 is a secondary side rectifier connected to the secondary winding of the transformer. A smoothing circuit, 5 is a primary side rectifying / smoothing circuit connected to the primary auxiliary winding of the transformer, and 6 is a transformer that insulates the primary side and the secondary side from each other and reduces the primary side input voltage to 2 by electromagnetic coupling. Converted to the required voltage on the secondary side. Reference numeral 7 is a detection circuit for detecting the secondary side output voltage output from the secondary side rectification / smoothing circuit, and 8 is obtained by the secondary side rectification / smoothing circuit 4 by discriminating the operation mode of the electronic device using the switching power supply. A microcomputer that operates by the secondary side output voltage and outputs a pulse wave of a specific frequency in the operation standby mode (standby mode), and 9 is a transmission circuit that transmits the pulse signal from the microcomputer 8 to the primary side.

The operation of the switching power supply device configured as described above will be described with reference to FIG.

First, when the equipment is in a normal operation state, the output voltage of the secondary side rectifying and smoothing circuit 4 is detected by the detecting circuit 7, and the detection result is detected by the primary side switch element drive control circuit 3.
To the control signal. By controlling the switch element drive circuit 2 by the primary side switch element drive control circuit 3, the oscillation frequency is determined, and the required load is supplied from the primary side to the secondary side via the switch element 1 and the transformer 6. To be done.

When the device changes from the normal operation state to the operation standby state, that is, when the secondary load shifts from large to small, a pulse signal having a preset frequency and duty is output from the microcomputer 8. Is output,
It is transmitted to the primary side switch element drive control circuit 3 through the transmission circuit 9. Primary side switch element drive control circuit 3
Then, by controlling the switch element drive circuit 2 at the oscillation frequency determined by the microcomputer 8,
The oscillation frequency is determined, and the required load is supplied from the primary side to the secondary side via the switch element 1 and the transformer 6 to operate.

As described above, according to the present embodiment, by controlling the oscillation frequency of the switching power supply by the control signal from the microcomputer 8, the conversion efficiency of the switching power supply when the device is in the standby state, that is, when the load is light. Can be improved.

[0017]

As described above, according to the present invention, the excellent effect that the conversion efficiency of the switching power supply device can be improved and the power consumption during the operation standby can be reduced can be obtained.

[Brief description of the drawings]

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

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

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 switch element 2 switch element drive circuit 3 primary side switch element drive control circuit 4 secondary side rectifying / smoothing circuit 5 primary side rectifying / smoothing circuit 6 transformer 7 detection circuit 8 microcomputer 9 transmission circuit

Claims (2)

[Claims] 1. A transformer having a primary auxiliary winding electromagnetically coupled to the primary winding and a secondary winding for obtaining an output voltage, and a primary connected to the primary side auxiliary winding of the transformer. Side rectifying / smoothing circuit, a secondary side rectifying / smoothing circuit connected to the secondary winding of the transformer, a detection circuit for detecting a secondary side output voltage obtained from the rectifying / smoothing circuit, and a primary winding of the transformer. A switch element that turns on and off the current flowing in the line and turns on when the control terminal voltage reaches the threshold voltage, a switch element drive circuit that turns on and off the switch element, and a feedback signal from the detection circuit Is obtained from the secondary rectifying / smoothing circuit by discriminating the operation mode of the primary side switching element drive control circuit for controlling the on-time of the switching element and stabilizing the secondary side output voltage, and the equipment using this device. The microcomputer is provided with a microcomputer that operates by a secondary side output voltage and outputs a pulse wave of a specific frequency in an operation standby mode, and a transmission circuit that transmits an output signal from the microcomputer to the primary side switch element drive control circuit. A switching power supply device characterized by the above. 2. The operation mode of a device using this device is determined, and when the determination result is the operation standby mode, a pulse wave of a specific frequency is output and transmitted to the primary side to turn on / off the switch element. The switching power supply device is characterized by improving the conversion efficiency under a light load by performing such control.