JPH03235658A - Switching regulator - Google Patents

Abstract

PURPOSE:To take out an auxiliary output arbitrarily regardless of the load status of the main output side of an output transformer by a method wherein the intermediate tap of the primary coil of the output transformer is grounded and, further, the one terminal of the primary coil is connected to the output part of a switching circuit and the other terminal is connected to a DC power supply. CONSTITUTION:An output transformer 4 which has a primary coil 5 having an intermediate tap 5m and one or more secondary coils 6a and 6b for taking out an auxiliary output is provided. The intermediate tap 5m is grounded and, further, the one terminal 5x of the primary coil 5 is connected to the output part 2O of a switching circuit 2 and the other terminal 5y is connected to a DC power supply, for instance the DC output part 7 in a main circuit system M. Therefore, the output of the switching circuit 2 is supplied to the main circuit system M and, at the same time, to the one terminal 5x of the primary coil 5 of the output transformer 4 which is connected in parallel with the switching circuit 2.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a switching regulator having a plurality of DC output sections.

[Conventional technology]

Conventionally, switching regulators shown in FIGS. 3 and 4 are known as switching regulators having a plurality of DC output sections.

The switching regulator 30 shown in FIG. 3 is constructed using a choke coil 31. First, the DC input to the DC input section 32 is switched by a switching circuit 34 using a switching transistor 33, and the output of this switching circuit 34 is is the rectifying and smoothing circuit 35
is supplied to the DC output section 36 of the main circuit system Ma. Therefore, the main output converted to direct current is obtained from the output section 36.

On the other hand, the primary coil 37 of the choke coil 31 constituting the sub-circuit system Sa is connected in series between the output part 34o of the switching circuit 34 and the DC output M2B5, and the secondary coil 38a
, 38b are rectified and smoothed circuits 43a, 4.
3b to the DC output sections 44a and 44b.

Therefore, the output parts 44λ and 44b provide DC sub-outputs.

In addition, in the figure, 45 is a driver circuit that controls on-off (duty ratio) of the switching transistor 33;
6 is a flyhole diode, and 47 is a smoothing capacitor.

Furthermore, the switching regulator 50 shown in FIG.
1c, and a common DC input section 52
has. Thereby, both the main output and the sub-output are taken out from each unit 51a, 51b, and 5tc, respectively. Note that the same parts as in FIG. 3 are given the same reference numerals, and the explanation thereof will be omitted. Also, 53 indicates a choke coil.

[Problem to be solved by the invention]

By the way, the conventional switching regulator 3 mentioned above
0.50 has the following problems.

In the former case, if the load on the main output side and the sub-output side is known in advance, the output will be distributed efficiently, but since the sub-output depends on (limited to) the load state on the main output side, If the load on the output side is small, the disadvantage is that a normal output cannot be output to the sub-output side or that the sum of the sub-outputs cannot be larger than the main output.

In the latter case, since each circuit system is independent, there is an advantage that the output of any circuit system can be taken out without being affected by the output state of other circuit systems. Because it corresponds to the system and requires no quantity,
This has the disadvantage of increasing noise, increasing costs, and increasing the size of the device.

[Means to solve the problem]

A switching regulator 1 according to the present invention has an output section 2o of a switching circuit 2 in a main circuit system M that obtains a main output.
When constructing a switching regulator that obtains one or more sub-outputs via an output transformer, a primary coil 5 with an intermediate cod 15m and one or more secondary coils 6a from which sub-outputs are taken out. , 6b.
, the intermediate tap 5m is connected to the ground 11, and one end 5x of the primary coil 5 is connected to the output section 20 of the switching circuit 2.
It is characterized in that the other end 5y is connected to a DC power supply, for example, a DC output s7 in the main circuit system M.

[For production]

According to the switching regulator I according to the present invention, the output of the switching circuit 2 is supplied to the main circuit system M, and at the same time is input to one end 5x of the primary coil 5 in the output transformer 4 connected in parallel.

The inductance of the primary coil 5 is set to a value that provides a predetermined output to the sub circuit system S when the duty ratio in the main circuit system M is minimum. As a result, a sub-output independent of the main circuit system M can be taken out from the secondary coils 6a, 6b of the output transformer 4.

Further, since the other end 5y of the primary coil 5 is connected to the DC output section 7 in the main circuit system M, which is a DC power supply, the output voltage of the secondary coils 6a and 6b can be stabilized against input voltage fluctuations and load fluctuations.

〔Example〕

Hereinafter, preferred embodiments of the present invention will be described in detail based on the drawings.

First, the configuration of a switching regulator 1 according to the present invention will be explained with reference to FIG.

11 is a ground line, and 12 is a DC input section.

This DC input section 12 includes an input section 2 of the switching circuit 2.
Connect 1. Switching circuit 2 is a switching FE
713 and a drive circuit 14, and the switching signal output from the drive circuit 14 is transferred to a switching FET.
It is applied to 13 gates to perform switching. As a result, the output section 2o of the switching circuit 2 obtains a switching output with a predetermined duty ratio. Further, a rectifier circuit 17 consisting of rectifier diodes 15 and 16, and a smoothing circuit 20 consisting of a choke coil 18 and a smoothing capacitor 19 are successively connected to the output section 2o of the switching circuit 2. The output side of the smoothing circuit 20 is connected to the DC output section 7.

The output of the DC output section 7 is divided by resistors 22 and 23 and fed back to the drive circuit 4, and the output voltage is controlled by controlling the duty ratio of the switching signal. As described above, the main output system M in the switching regulator 1 is configured.

On the other hand, S is a sub-output system, and the A-system S is equipped with an output transformer 4. The output transformer 4 has a primary coil 5 having an intermediate tap of 5 m and two systems of secondary coils 6a and 6b. The intermediate tap 5m is connected to the ground line 11, one end 5x of the primary coil 5 is connected to the output section 20 of the switching circuit 2, and the other end 5y is connected to the DC output of the main circuit system M via the reverse current blocking diode 25. 7 respectively.

On the other hand, one secondary coil 6a is a rectifier diode 26a1.
The other secondary coil 6b is connected to the first DC output section 29a on the sub-output side via a rectifying and smoothing circuit 28a consisting of a smoothing capacitor 27a, and the other secondary coil 6b is connected to the rectifier diode 2.
Rectifier smoothing circuit 28 consisting of 6b1 smoothing capacitor 27b
b to the second DC output section 29b on the sub-output side.

Next, the operation and function of the switching regulator 1 according to the present invention will be explained with reference to FIGS. 1 and 2.

First, a direct current is input to the direct current input section 12 and is supplied to the input section 21 of the switching circuit 2 . switching FET
13 is turned on and off by a switching signal given from the drive circuit 14, and is connected to the output section 2 of the switching circuit 2.
o, an output switched to a predetermined duty ratio is obtained. Then, the output from the output section 20 is converted into a direct current through the rectifier circuit 17 and the smoothing circuit 20 in the main circuit system M,
It is taken out from the DC output section 7 as the main output.

Further, the output of the switching circuit 2 is also supplied to the sub-circuit system S, and is inputted to one end 5x of the primary coil 5 to which the intermediate tap 5m of the output transformer 4 is grounded.

Note that the other end 5y of the primary coil 5 is connected to the DC output section 7 of the main circuit system M. Therefore, the secondary coils 6a, 6
In b, an output voltage is obtained based on the input voltage and winding ratio of the primary coil 5, and the output voltage is stabilized. That is, as shown in FIG. 2, if the magnitude of the DC voltage of the DC output section 7 in the main circuit system M is Eo, the secondary coil 6
The output voltage Vo of the DC output section 29a (29b) at a (6b) is Vo= ((Eo+Vd+) ・(nz/n+) )
-Vdt, and a stable sub-output determined by the voltage Eo can be obtained even with input voltage fluctuations and load fluctuations.

Note that when the load on the main circuit system M is small, the duty ratio of the switching signal output from the drive circuit 14 becomes small and the off period of the switching PET 13 becomes long. Even if the load of the main circuit system M is the minimum,
This can be dealt with by setting an inductance in the sub-circuit system S to a level that allows a predetermined load output to be obtained.

In this way, the DC voltage output from the sub-circuit system S is stabilized, and if the inductance value of the primary coil 5 in the choke coil 18 and the output transformer 4 is considered, the output state of the main circuit system M is limited. Not done.

Although the embodiments have been described in detail above, the present invention is not limited to these embodiments.

For example, although the other end of the primary coil in the output transformer is connected to the DC output part of the main circuit system, it can be connected to any other DC power source such as a DC input part. Furthermore, although PET is used as an example of the switching element, it is of course possible to use a general transistor or the like. In addition, the detailed circuit configuration, circuit elements, etc. may be arbitrarily changed without departing from the gist of the present invention.

〔Effect of the invention〕

As described above, the switching regulator according to the present invention includes an output transformer having a primary coil with an intermediate tap and one or more secondary coils for taking out the auxiliary output, the intermediate tap being grounded, and one end of the primary coil being connected to the ground. Since it is connected to the output part of the switching circuit and the other end is connected to a DC power supply, the sub-output can be taken out arbitrarily without depending on (limited to) the load condition on the main output side. Furthermore, compared to conventional switching regulators that use a plurality of independent switching regulator units, the present invention has remarkable advantages in that the number of parts can be reduced by simplifying the circuit configuration, reliability can be improved, and costs can be reduced.

[Brief explanation of drawings]

FIG. 1 is an electric circuit diagram of a switching regulator according to the present invention; FIG. 2 is a functional explanatory diagram of the same switching regulator; FIGS. 3 and 4 are electrical circuit diagrams of a switching regulator according to the prior art. In the drawing, 1 Ni switching regulator 2 Ni switching circuit 2o: Output section 4: Output transformer 5 Ni primary coil 5X One end 5
y; Other end 5m: Intermediate taps 6a, 6b: Secondary coil 7. DC output section M: Main circuit system

Claims (1)

[Scope of Claims] [1] In a switching regulator in which one or more auxiliary outputs are obtained from the output section of a switching circuit in a main circuit system that obtains a main output via an output transformer, a primary with an intermediate tap is provided. It is equipped with an output transformer having a coil and one or more secondary coils from which sub-outputs are taken out, the intermediate tap is grounded, one end of the primary coil is connected to the output part of the switching circuit, and the other end is connected to a DC power supply. A switching regulator characterized in that it is connected to. [2] The switching regulator according to claim 1, wherein the other end of the primary coil is connected to a DC output section in the main circuit system.