JPH09331672A - Switching power-supply unit - Google Patents

Abstract

PROBLEM TO BE SOLVED: To use the electric parts of a switching power-supply unit in common with other ones and improve their productivities, by interposing a second reactor between the positive side of its input power supply and its first switching element, and by dealing with the high or low voltage of its input power supply merely through altering the second reactor. SOLUTION: Connecting in series with each other a first switching element 4 and a first reactor 10 which are interposed between the positive side of an input power supply 14 and the positive side of a load 15, a second reactor 3 is interposed between the positive side of the input power supply 14 and the first switching element 4. Thereby, since the voltage generated at a point (E) is associated with a voltage division by the values of the first and second reactors 10, 3, the value of the second reactor 3 is altered in response to the voltage specification of the input power supply 14 to make the arbitrary setting of the voltage at the point E possible. Therefore, the dealing with the voltage of the input power supply 14 is made possible merely by the alteration of the reactor 3 even when the voltage is high, and the parts and circuits of a switching power-supply unit can be shared with other ones to improve theri productivites.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a switching power supply device which can be used mainly for a step-down switching power supply device which uses a high voltage power supply as an input source and steps down to a low constant voltage.

[0002]

2. Description of the Related Art A conventional technique will be described with reference to FIGS. 5 is an electric circuit diagram of the switching power supply device when the input power supply is relatively low, and FIG. 6 is an electric circuit diagram of the switching power supply device when the input power supply is relatively high.

According to FIG. 5, the first switching element 4 composed of an FET connected to the positive side of the input power source 14, the first reactor 10, the smoothing capacitor 12, and the smoothing capacitor 12 via the first reactor 10 are shown. A first diode 7 called a flywheel switch connected in parallel with the first switching element 4 and a PWM
As shown in the figure, the capacitor 11 and the load 1 are composed of a control circuit 9 including a pulse generation circuit for supplying pulses.
The other ends of the control circuit 9, the first diode 7, and the smoothing capacitor 12, including 5, are connected to the negative side of the input power supply 14.

In the above structure, the first switching element 4 is turned on / off by the pulse signal from the control circuit 9 to supply a constant voltage controlled voltage to the load 15.

Further, in the switching power supply device according to FIG. 6, the first switching element 4 and the second switching element connected in parallel with the first diode 7 in place of the control circuit 9 of FIG. The control circuit 19 is composed of a pulse generation circuit for controlling 18
ON / OFF control of the switching element 4 and the second switching element 18 of the load circuit 1 by the pulse signal from the control circuit 19 reduces the voltage from the input power source 14
5 is supplied with a constant-voltage-controlled voltage.

[0006]

However, in the above-mentioned conventional configuration, the loss of the component and the voltage applied to the component change depending on the level of the input power source 14, and therefore the control circuit 9 or 19 and the first switching element 4 However, the second switching element 18, the reactor 10 and the like need to be changed, parts cannot be shared, inventory management in assembly is complicated, and productivity is poor.

The present invention is intended to solve the above-mentioned problems, in which parts can be shared and the types of circuit parts can be reduced.
Further, it is an object of the present invention to provide a switching power supply device capable of improving productivity.

[0008]

In order to solve the above problems, the present invention provides a series circuit of a first switching element and a first reactor inserted in a plus line between an input power source and a load, and A smoothing capacitor connected in parallel to the load between the load and the reactor; a first diode having one end connected between the reactor and the first switching element and the other end connected to the negative side of the load; 1
Between the first switching element and a control circuit for outputting a pulse to the switching element to turn on / off the first switching element, a capacitor connected in parallel to the input power source, Second inserted in
And a third reactor electromagnetically coupled to the second reactor, one end of which is connected to the positive side of the input power source through the second diode and the other end of which is connected to the negative side of the input power source. It is possible to cope with the high and low of the voltage of the input power supply only by changing the second reactor, and other electric circuit parts can be made common and the second reactor can be pre-assembled. Therefore, productivity can be improved.

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION The invention according to claim 1 of the present invention is
The first inserted in the positive line between the input power supply and the load
A switching element and a series circuit of a first reactor,
A smoothing capacitor connected in parallel with the load between the load and the reactor; a first diode having one end connected between the reactor and the first switching element and the other end connected to the negative side of the load; A control circuit for outputting a pulse to a first switching element to turn on / off the first switching element, a capacitor connected in parallel to the input power source, a positive side of the input power source, and a first side.
And a second reactor inserted between the switching elements, and one end of which is electromagnetically coupled to the second reactor and which is connected to the plus side of the input power source through a second diode and the other end of which is connected to the input power source. It can be configured with a third reactor connected to the negative side, and can cope with high and low voltage of the input power source only by changing the second reactor, and other electric circuit parts can be shared, and Since the second reactor can be assembled in advance without being assembled, the productivity can be improved.

According to a second aspect of the present invention, the series circuit of the first switching element and the first reactor inserted in the positive line between the input power source and the load, and between the load and the reactor. A smoothing capacitor connected in parallel to the load; a first diode having one end connected between the reactor and the first switching element and the other end connected to the negative side of the load; and a pulse applied to the first switching element. To turn on the first switching element.
A control circuit for turning off, a capacitor connected in parallel to the input power supply, a second reactor inserted between the positive side of the input power supply and the first switching element, and a parallel connection to the second reactor. A series circuit of a second diode and a capacitor, and a connection point of the second diode and the capacitor, and a third circuit connected to the negative side of the input power source.
It is possible to cope with high and low voltage of the input power source only by changing the second and third reactors, and it is possible to share the electric circuit parts and to preliminarily use the second and third reactors. Since it can be assembled excluding the reactor, the productivity can be improved.

FIG. 1 shows an embodiment of the present invention.
This will be described with reference to FIG. In the description, the same parts as those in the prior art will be designated by the same reference numerals.

(Embodiment 1) FIG. 1 is an electric circuit diagram of an embodiment of the present invention, and FIG. 2 is an operation waveform diagram thereof. According to the figure, the switching power supply unit has an F-line inserted in the positive line between the DC input power supply 14 and the load 15.
A series circuit of a first switching element 4 and a first reactor 10 made of ET, a smoothing capacitor 12 connected in parallel to the load 15 between the load 15 and the reactor 10, the reactor 10 and the first switching. A first diode 7 called a flywheel switch, one end of which is connected between the elements 4 and the other end of which is connected to the negative side of the load 15, and a pulse is output to the first switching element 4 to output the first switching element. A control circuit 9 for turning on / off the element 4, a capacitor 11 connected in parallel to the input power source 14, a positive side of the input power source 14, and a first side.
The second reactor 3 inserted between the switching elements 14 and a second diode 16 which is electromagnetically coupled to the second reactor 3 and has one end called a flywheel switch, and the positive side of the input power supply 14 And a third reactor 8 having the other end connected to the negative side of the input power supply 14.

Next, the operation of the switching power supply device will be described. The first switching element 4 is shown in FIG.
The load 15 is controlled by on / off control as shown in
A constant-voltage controlled voltage can be supplied to. First
During the ON period t1 to t2 of the switching element 4, the current is supplied to the closed circuit including the input power source 14, the second reactor 3, the first switching element 4, the first reactor 10, the smoothing capacitor 12, and the load 15. Flowing. At this time, the current I ₁ flowing through the second reactor 3 gradually increases as shown in FIG. 2B due to the inductance of the second reactor 3 and the first reactor 10.

The third reactor 8 is in a reverse bias state because a voltage from right to left is generated during the ON period of the first switching element 4, and the second diode 16 is kept off. The first diode 7 has an input power supply 14
The difference (V _IN -V _O) voltage of the second reactor 3 and divided reverse voltage in the inductance value of the first reactor 10 of the voltage V ₀ which voltage V _IN and the load 15 is applied in Therefore, it is kept off.

During the off period of the first switching element 4 shown at t2 to t3 in FIG. 2, a voltage going from left to right is generated in the third reactor 8, so that the second diode 16 is turned on. The current I ₂ shown in FIG. 2C flows through the closed circuit of the third reactor 8, the second diode 16, the input power supply 14, and the ground terminal 5. The energy stored in the second reactor 3 is regenerated to the input power supply 14 by the flow of the current I ₂ . Since a voltage from left to right is generated in the first reactor 10, the first diode 7 is turned on, and a current flows in the closed circuit of the first reactor 10, the smoothing capacitor 12, and the ground terminal 6. In the period of one cycle t1 to t3, the smoothed current shown in FIG. 2D flows through the first reactor 10.

In the case of the present embodiment, the second reactor 3
When the first switching element 4 turns on the voltage of the input power supply 14 connected to the first terminal 1 by providing the voltage, the voltage generated at the point E in FIG. 1 is the same as that of the second reactor 3 and the first reactor. Input power supply 1 because it is divided by 10 values
By changing the value of the second reactor 3 according to the voltage specification of No. 4, the voltage at the point E can be freely set. That is, the value can be adjusted by increasing the value of the second reactor 3 when the voltage of the input power supply 14 is high and decreasing the value of the second reactor 3 when the voltage of the input power source 14 is low.

(Second Embodiment) FIG. 3 is a circuit diagram of another embodiment of the present invention, and FIG. 4 is a waveform diagram of the same operation.

According to the figure, the switching power supply is
A series circuit of the first switching element 4 and the first reactor 10 which are FETs inserted in the positive line between the input power supply 14 and the load 15, the load 15 and the first
Smoothing capacitor 12 connected in parallel to the load 15 between the reactors 10, and the first reactor 10 and the first reactor 10.
One end is connected between the switching elements 4 of and the other end is the load 1
A first diode 7 called a flywheel switch connected to the negative side of 5; and a control circuit 9 for outputting a pulse to the first switching element 4 to turn on / off the first switching element 4. The input power source 14
A capacitor 11 connected in parallel with the input power supply 1
A second reactor 3 inserted between the positive side of 4 and the first switching element 4, and a second diode 16a called a flywheel switch connected in parallel to the second reactor 3 and a series circuit of a capacitor 13. And a connection point between the second diode 16a and the capacitor 13 and a third reactor 8a connected to the negative side of the input power supply 14.

Next, the operation of the above switching power supply device will be described. The first switching element 4 is shown in FIG.
The load 15 is controlled by on / off control as shown in
A constant-voltage controlled voltage can be supplied to. First
During the ON period t1 to t2 of the switching element 4, the current flows through the closed circuit including the input power supply 14, the second reactor 3, the first switching element 4, the smoothing capacitor 12, and the load 15.

At this time, the current I ₁ flowing through the second reactor 3 gradually increases as shown in FIG. 4B because of the inductance of the second reactor 3 and the first reactor 10. Since the capacitor 13 is charged to the power source voltage or more during the off period of the first switching element 4, the capacitor 13, the first switching element 4, and the first reactor 10 are charged during the on periods t1 to t2 of FIG. The discharge current I ₄ of the capacitor 13 flows in a closed circuit composed of the smoothing capacitor 12 and the load 15 and the third reactor 8a, power is supplied to the load 15, and the current I ₂ flows to the third reactor 8 to generate energy. Accumulated.

During the OFF period of the first switching element 4 shown at t2 to t3 in FIG. 4, the second reactor 3 has a polarity for generating a voltage going from right to left. The charging current I ₄ of the capacitor 13 flows in the closed circuit of the reactor 3, the capacitor 13 and the second diode 16, and the discharging current I ₂ flows in the closed circuit of the third reactor 8, the second diode 16 and the capacitor 11. Energy is regenerated in the capacitor 11.

In the period of one cycle t1 to t3, the smoothed current shown in FIG. 4 (D) flows through the first reactor 10.

The voltage generated at the point E in FIG. 3 is the same as that in the first embodiment, and the description thereof will be omitted.
The same adjustment as that of the first embodiment can be performed by the reactor.

[0024]

As described above, according to the present invention, even when the input DC power source is high by providing the second reactor, the same control circuit as in the case where the input DC power source is low only by changing the second reactor, Switching elements and smooth chokes can be used, and parts and circuits can be shared. Therefore, the cost of the step-down switching power supply device can be reduced.

[Brief description of drawings]

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

FIG. 2 is an operation waveform diagram of the same.

FIG. 3 is an electrical circuit diagram of the other embodiment.

FIG. 4 is an operation waveform diagram of the same.

FIG. 5 is an electrical circuit diagram of a conventional switching power supply device.

FIG. 6 is an electrical circuit diagram of the other switching power supply device.

[Explanation of symbols]

 1 1st terminal 2 2nd terminal 3 2nd reactor 4 1st switching element 5 1st ground terminal 6 2nd ground terminal 7 1st diode 8 and 8a 3rd reactor 9 Control circuit 10th Reactor 1 1 Capacitor 12 Smoothing capacitor 13 Capacitor 14 Input power supply 15 Load 16, 16a Second diode

Claims (2)

[Claims] 1. A series circuit of a first switching element and a first reactor inserted in a positive line between an input power supply and a load, and a smoothing capacitor connected in parallel to the load between the load and the reactor. A first diode having one end connected between the reactor and the first switching element and the other end connected to the negative side of the load; and a pulse output to the first switching element to output the first switching element. A control circuit for turning on / off the element, a capacitor connected in parallel to the input power source, and a second capacitor inserted between the positive side of the input power source and the first switching element.
And a third reactor electromagnetically coupled to the second reactor, one end of which is connected to the positive side of the input power source through the second diode and the other end of which is connected to the negative side of the input power source. And a switching power supply device. 2. A series circuit of a first switching element and a first reactor inserted in a positive line between an input power source and a load, and a smoothing capacitor connected in parallel to the load between the load and the reactor. A first diode having one end connected between the reactor and the first switching element and the other end connected to the negative side of the load; and a pulse output to the first switching element to output the first switching element. A control circuit for turning on / off the element, a capacitor connected in parallel to the input power source, and a second capacitor inserted between the positive side of the input power source and the first switching element.
, A series circuit of a second diode and a capacitor connected in parallel to the second reactor, a connection point of the second diode and the capacitor, and a third reactor connected to the negative side of the input power supply. Switching power supply device composed of.