JPH06165483A - Multi-output switching power-supply device - Google Patents

Abstract

PURPOSE:To provide a multi-output switching power-supply device satisfying the requirement of multi-outputs, high efficiency, miniaturization and the decrease of the number of components. CONSTITUTION:A control section 23 generating a switching driving signal, a switching element 22 brought to an on or off state in response to the switching driving signal, an input capacitor 21, in which input electrical energy is stored, and a transformer 26, which converts energy stored in the input capacitor 21 during a period when the switching element 22 is tuned on into magnetic energy and in which converted energy is stored, are provided. The title power-supply device has an output capacitor 25, which converts magnetic energy into electrical energy during a time when the switching element 22 is turned off and in which electrical energy is stored and which supplies the outside with specified output voltage, a loop diode 24 forming a current path between the primary side coil of the transformer and an output transformer and a secondary circuit supplying a plurality of output voltage of voltage different from said specified output voltage from the secondary side of the transformer.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a multi-output switching power supply device which can obtain a plurality of DC power supplies with high efficiency.

[0002]

2. Description of the Related Art Conventionally, there are roughly three types of switching power supply systems, and FIGS. 1 to 3 show these configurations.

FIG. 1 is a block diagram of a chopper type step-down power supply device. 1 is a capacitor for input power storage, 2 is a switching element such as FET, 3 is a control unit for controlling the switching element, and 4 is current energy. Inductance to be accumulated, 5 is a diode, 6 is an output capacitor that absorbs noise components such as ripples and supplies an output voltage, and 7 is a variable resistor that detects the output voltage and feeds back the detected voltage to the control unit.

Next, the operation of the configuration shown in FIG. 1 will be described. The switching element 2 is turned on or off at high speed by the switching drive signal from the control unit 3. While the switching element 2 is on, current energy is stored in the inductance 4. On the other hand, while the switching element 2 is off, the current energy accumulated in the inductance 4 is charged in the output capacitor via the diode 5. The charging voltage of this output capacitor is supplied to the outside as an output voltage. This type of power supply device outputs a voltage lower than the input DC voltage. The value of this output voltage is determined by the switching drive signal from the control unit 3.

FIG. 2 is a block diagram of a ringing type boosting power supply device, and the same components as those of FIG. 1 are designated by the same reference numerals and the description thereof will be omitted. In FIG. 2, reference numeral 8 is a Zener diode for a flywheel. The operating principle of the configuration of FIG. 2 is the same as that of the configuration of FIG. 1, but a current flows through the Zener diode 8 even when the switching element is off. With this configuration, an output voltage higher than the input DC voltage can be obtained.

FIG. 3 is a block diagram of a flyback type switching power supply device. The same components as those in FIGS. 1 and 2 are designated by the same reference numerals and the description thereof will be omitted. In FIG. 3, 9 is a flyback transformer, 10 and 1
Reference numeral 1 is a diode connected to an independent winding on the secondary side of the transformer, and 12 and 13 are output capacitors for the respective windings. The features of this configuration are that the primary side and the secondary side can be isolated in a direct current manner, and that a plurality of output voltages can be supplied to the outside. Although the efficiency is good, there is a drawback that the primary side and the secondary side cannot be isolated and a single output cannot be obtained. Further, the ringing type booster power source shown in FIG. 2 has a drawback that only a single output can be obtained as in the problem of isolation.
Further, the flyback type switching power supply shown in FIG. 3 has a drawback that isolation can be taken easily and multiple outputs are possible, but the efficiency is poor.

[0007]

However, each of the above conventional switching devices has advantages and disadvantages. The chopper type step-down type power supply device and the ringing type step-up power supply device have high efficiency, but have a drawback in that primary side and secondary side cannot be isolated and a single output cannot be obtained.

Further, the flyback type switching power supply device has a drawback that it is not only efficient in isolation but capable of multiple outputs, but is inefficient.

[0009] Therefore, when facing the problems of multiple outputs, high efficiency, miniaturization, and reduction in the number of components often required by electronic equipment, a plurality of these devices are driven in parallel to find a compromise and a power supply device. Was configured.
In such a configuration, the cost of the device is increased, and a new problem arises in that it suffers from the frequency beat of each control unit due to the parallel driving.

The present invention solves such conventional problems, and satisfies the demands of multiple outputs, high efficiency, miniaturization, and reduction in the number of parts. Further, in particular, when obtaining a plurality of outputs from one input, it is effective when the output capacity ratio is concentrated on one output.

[0011]

In order to achieve the above object, the present invention provides a control unit for generating a switching drive signal,
A switching element that is turned on or off according to the switching drive signal, an input capacitor that stores electric energy of an input DC voltage and supplies the electrical energy to the switching element, and the input during a period when the switching element is turned on. A transformer for converting energy stored in a capacitor into magnetic energy and storing the same, and an output capacitor for converting the magnetic energy into electric energy and storing the same to supply a predetermined output voltage to the outside during a period in which the switching element is turned off. A loop diode that forms a current path between the primary coil of the transformer and the output transformer; and a secondary diode that supplies a plurality of output voltages different from the predetermined output voltage from the secondary side of the transformer. The following circuit is included.

[0012]

The present invention has the following actions due to the above-mentioned constitution. That is, the electric energy stored in the input side capacitor is closed for a certain period by the switching element, flows into the primary side coil of the transformer, and is stored as the flux in the core of the transformer. The next momentary switching element opens, the charging of electrical energy is stopped, and as the next step, the primary side flux is short-circuited by the loop diode, and this is stored in the output side capacitor. By monitoring the accumulated amount and controlling the switching opening / closing time, the voltage can be reduced without loss. At that time, if another outlet is provided in the cycle where the transformer flux is discharged, a free voltage can be selected while ensuring complete isolation, and if the coupling between the coils is made tight, stable multiple output It becomes possible to control.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT An embodiment of the present invention will be described below with reference to FIG.

FIG. 1 shows the configuration of an embodiment of the present invention. Reference numeral 21 is an input power storage capacitor, 22 is a switching element, 23 is a control unit having an oscillator for controlling the switching time of the switching element, a triangular wave generator, a reference voltage source and a comparator, and 24 is a discharge of stored flux. Loop diode, 25 is a capacitor that stores and outputs this energy.
Reference numeral 1 is an output voltage monitoring volume. Further, reference numeral 26 is a transformer, and a positive power source is obtained at a portion constituted by the diode 27 and the capacitor 28, and a negative power source is obtained at a portion constituted by the diode 29 and the capacitor 30. Reference numeral 31 is a variable resistor for detecting an output voltage, as in the conventional example.

Next, the operation of the above embodiment will be described. The electric energy stored in the input-side capacitor 21 flows into the primary side coil of the transformer 26 during the period when the switching element 22 is turned on, and the electric energy is transferred to the transformer 26.
It is stored as flux in the core. When the next momentary switching element 22 is turned off, the charging of electric energy is stopped, and as a next step, the loop diode 24
Therefore, the primary side flux is short-circuited, and this is accumulated in the output side capacitor 25. By monitoring the accumulated amount and controlling the opening / closing time of the switching element 22, the voltage can be reduced without loss. At that time, if another discharge outlet is provided in the cycle in which the flux of the transformer 26 is discharged, a free voltage can be selected while ensuring complete isolation, and the coupling between the coils of the transformer 26 can be made tight. If so, stable multiple output control becomes possible.

[0016]

As is apparent from the above embodiment, the present invention has the advantages of flyback type high efficiency and miniaturization and the advantages of flyback type multi-output power supply, and is supplied by a chopper system. The higher the capacity ratio of the main line system, the higher the efficiency. Chopper type exchange efficiency eta ₁ of the power supply as an example, each P _2, P exchange efficiency eta ₂ of the flyback power supply, the capacitance of the output-side main line P _1, the branch system as two output
_{If it is 3} , the exchange efficiency η is expressed by (Equation 1).

[0017]

[Equation 1]

Usually, η ₁ ≈0.9 and η ₂ ≈0.6, so
The total capacity of the flyback branch line system (P ₂ + P ₃ )
The smaller the ratio to the capacity before output, the higher η.

[Brief description of drawings]

FIG. 1 is a block diagram of a multi-output switching power supply device according to the present invention.

FIG. 2 is a block diagram of a conventional chopper type step-down power supply device.

FIG. 3 is a block diagram of a conventional ringing type booster power supply device.

FIG. 4 is a block diagram of a conventional flyback type switching power supply device.

[Explanation of symbols]

 21 Input Capacitor 22 Switching Element 23 Control Section 24 Loop Diode 25 Output Capacitor 26 Transformer 27 Diode 28 Output Capacitor 29 Diode 30 Output Capacitor 31 Variable Resistor

Claims (1)

[Claims] 1. A control unit that generates a switching drive signal, a switching element that is turned on or off according to the switching drive signal, and electric energy of an input DC voltage is accumulated and supplied to the switching element. An input capacitor, a transformer that converts and stores energy stored in the input capacitor into magnetic energy during a period in which the switching element is on, and a magnetic energy into electrical energy during a period in which the switching element is off. Output capacitor that accumulates and supplies a predetermined output voltage to the outside, a loop diode that forms a current path between the primary coil of the transformer and the output transformer, and the predetermined value from the secondary side of the transformer. A secondary circuit that supplies a plurality of output voltages different from the output voltage. Output switching power supply.