JPS6244066A - Power source circuit - Google Patents

Abstract

PURPOSE:To obtain an auxiliary power source which varies in response to the variation in the main output of a switching regulator with a simple configuration by constructing the power source by using an auxiliary winding of an inductor connected with the output side of a switching element. CONSTITUTION:A power supplied from a DC power source DSC is switched by a switching element SWE, and supplied through an inductor IT to a load L. The outputs of the secondary and tertiary windings 6, 7 electromagnetically coupled with the primary winding 5 of the inductor L are half-wave rectified by diodes 8, 8 an capacitors 10, 11 as an auxiliary power and power which varies in a direction coincident to the direction of the variation in the main output of a switching regulator or in reverse direction is supplied to the loads 12, 13.

Description

[Detailed description of the invention] (Industrial application field) The present invention relates to a power supply circuit used in electronic equipment and the like.

(Prior Art) A means for controlling the opening and closing of power supplied from a DC power supply by a switching element whose opening and closing is controlled by a switching pulse, and a means for controlling the opening and closing of power supplied from a DC power supply by a switching element whose opening and closing are controlled by a switching pulse, and a means for controlling the opening and closing of the switching element with a connection polarity such that the switching element is in a conductive state when the switching element is in a cut-off state. A flywheel diode connected between the output side and a DC power supply, and an inductor provided between the output side of the switching element and the load, and the ratio between the conduction time and the cutoff time of the switching element is determined. 2. Description of the Related Art Various types of power supply circuits have been known that include a switching regulator that can control the voltage applied to a load by changing the voltage.

FIG. 7 is a block diagram showing an example of the configuration of a conventional power supply circuit having the above-mentioned configuration. In FIG. is given to.

For example, a switching element SwE using a transistor or a thyristor is controlled to open and close by a switching pulse P supplied to a terminal 1 from a switching pulse supply Jkim (not shown), and is supplied from a DC power supply DC5. The DC power is controlled to open and close and is sent to the output side.

D is the connection polarity of the switching element 5 such that it becomes conductive when the switching element 511B is cut off.
IllE output side and DC II! A flywheel diode connected between wXDC5 and C
lIC is an inductor (choke coil) connected between the output side of the switching element SvE and the load, and C is a smoothing capacitor.

f! configured as shown in FIG. Put on the power circuit.

The DC voltage supplied from the DC t[ocs to the switching element 5IIH is Eb, and the switching element 5
The conduction time of IIIB is Ton, and the switching element SVH
Assuming that the cutoff time is Toff, the DC voltage Eb' supplied to the load is expressed by the following equation, as is well known.

Eb' = Eb-Ton/(Ton+Toff)(
(problems to be solved by the invention)
Is the TG circuit DC? 5 @ The DC voltage Eb of the DC power supply DC5 is changed by changing the duty cycle of the switching pulse according to the fluctuation of the DC voltage Eb of the DC5.
It is used so that the DC voltage Eb'' supplied to the load always remains constant even when the voltage fluctuates, or by changing the duty cycle of the switching pulse P in order to change the operating conditions of the load depending on the purpose. Therefore, the conduction time Ton and the cutoff time T o in the switching element SWE are
DC voltage E supplied to the load by changing the ratio with ff
It is sometimes used by varying b'.

Of the two usage methods described above in a power supply circuit, the latter usage method is adopted, for example, when a horizontal deflection circuit with a variable horizontal deflection frequency is used as a load of the power supply circuit. In other words, in order to perform deflection with a constant deflection width regardless of changes in the horizontal deflection frequency,
Operating DC voltage Eb supplied to the horizontal deflection circuit of the load
It is necessary to vary ' in approximately proportion to the frequency of the horizontal deflection current to be generated in the horizontal deflection circuit. The usage method is adopted.

However, inside this type of electronic equipment, in order to correct the operation in response to changes in the deflection frequency, an auxiliary voltage that changes in accordance with changes in the horizontal deflection frequency is required in addition to the above-mentioned DC voltage Eb'. It is sometimes said that For example, in the horizontal deflection excitation stage, horizontal deflection oscillation stage, etc., good results may be obtained by correcting the circuit operation by applying an appropriate voltage that changes according to the horizontal deflection frequency to them. It is from.

The correction voltage described above can be obtained by dividing the DC voltage Eb' using a resistor, etc., but when such a method is adopted, it naturally has the disadvantage of large power loss. arise.

Moreover, the conditions for the above-mentioned correction voltage depend on whether it is proportional or inversely proportional to the horizontal deflection frequency, and whether the polarity of the required voltage is positive or negative, depending on the circuit. Since the characteristics vary, there are many cases in which the above-mentioned DC voltage Eb' cannot be handled simply by dividing it, and a solution to this problem has been sought.

(Means for Solving the Problems) The present invention provides a means for controlling the opening and closing of power supplied from a DC power supply by a switching element which is controlled to open and close by a switching pulse, and a means for controlling the opening and closing of power supplied from a DC power source, and a conductive state when the switching element is in a cut-off state. A diode connected between the output side of the switching element and the DC power supply with such connection polarity,
A switching device comprising an inductor provided between the output side of the switching element and the load, and the voltage applied to the load can be controlled by changing the ratio between the conduction time and the cutoff time of the switching element. In a power supply circuit including a regulator, an inductor having an auxiliary winding electromagnetically coupled to its winding is used as the inductor.

Provided is a power supply circuit that half-wave rectifies the rectangular wave voltage generated in the auxiliary winding of the implanter and uses it as an auxiliary power source to generate a voltage that fluctuates depending on the ratio of the conduction time and cut-off time of the switching element. It is.

(Example) Hereinafter, specific contents of the IT power supply circuit of the present invention will be explained in detail with reference to the accompanying drawings. FIG. 1 is a circuit diagram of an embodiment of the power supply circuit of the present invention, and in this FIG. The same drawing numerals as those used in FIG. 7 are used for parts.

In the power outlet path of FIG. 1, DC t! A DC voltage Eb is applied from wXocs to the switching element SWE. For example, the switching element SVE uses a transistor or a thyristor. By being controlled to open and close by the pulse P, the DC power supplied from the DC type 117XDC3 is controlled to open and close and is sent to the output side.

D is a switching element Sw with a connection polarity such that it becomes conductive when the switching element SE is in a cut-off state.
E output side and DC power supply DCI! In the figure, C is a smoothing capacitor. Further, IT is an inductor, the primary winding 5 of which is connected between the output side of the switching element SwE and the load line, and the inductor IT
A secondary winding 6 and a tertiary winding 7 are wound around. The secondary winding 6 described above includes a rectifier diode 8 and a capacitor 10.
Load 1 through a rectifying and smoothing circuit composed of
Further, a load 13 is connected to the tertiary winding 7 described above through a rectifying and smoothing circuit constituted by a rectifying diode 9 and a capacitor 11.

In the power supply circuit having the configuration shown in the first diagram, the DC type @
The DC voltage supplied from DC5 to the switching element SvC is Eb, and the switching element 5IIIE
Let Ton be the conduction time of the switching element SwE, and Toff be the cutoff time of the switching element SwE, the DC voltage Eb' supplied to the load through the primary winding 5 of the inductor IT is expressed as the following equation, as is well known.

Eb' = Eb-Ton/(Ton+Toff) Therefore, the DC voltage Eb' supplied to the load changes the ratio of the conduction time Ton to the cut-off time Toff of the switching element SvE, that is, the duty cycle of the switching pulse P. It can be changed by

Now, the DC voltage Eb from the DC power supply DC5 is changed to Eb
The secondary winding 6 and the tertiary winding M7 of the inductor IT are applied to the primary winding 5 of the inductor IT as a rectangular wave voltage as shown in (,) in FIG.
is the turns ratio of the primary winding 5 and the secondary winding IIA6 and 1
If the winding ratio of the secondary winding 5 and the tertiary winding 7 is n, then the secondary winding 6 and the tertiary winding 7 described above have nE, respectively.
A rectangular wave voltage of b is generated (in implementing the present invention,
It goes without saying that the winding ratio between the primary winding 5 and the secondary winding 6 and the winding ratio between the primary winding M5 and the tertiary winding 7 described above may be set arbitrarily. do not have).

If the polarity of the voltage generated in the secondary winding M6 and the tertiary winding is as shown in the figure,
The rectangular wave voltages appearing in the secondary winding 6 and the tertiary winding 7 have opposite polarities, as shown in FIGS. 2(b) and 2(c), respectively.

In addition, in (b) and (C) of Fig. 2, the 0-0 line indicated by the dotted line in Fig. 1 is the AC axis line (average level), and the area of the above and below 0-Oa in the rectangular wave is equal.

Now, the output voltage Eb of the DC power supply DC5 is constant, and the switching element 5WIl! When the period of the opening/closing operation is constant, when the ratio of the conduction time Ton to the cutoff time Toff (duty cycle of the switching pulse P) in the switching element SUE is changed, the secondary winding IR6 of the inductor As illustrated in FIGS. 3(a) and 3(b), the generated rectangular wave voltage varies depending on the alternating current axis, W, depending on the change in duty cycle.
+O-O changes, and the rectangular wave voltage generated in the tertiary winding 'IIA7 changes as the duty cycle changes, as illustrated in Figure 4 (a) and (b). AC axis 0-0 changes.

Then, the rectangular wave voltage generated in the secondary winding of the inductor 11X6 as illustrated in (a) and (b) of FIG. The rectified and smoothed voltage E1 is the load 1
2 and also generated in the tertiary winding 7 of the inductor IT, the rectangular wave voltage as illustrated in FIGS.
The voltage E2 rectified and smoothed by the rectifier circuit consisting of is supplied to the load ]3.

The voltage E1 supplied to the load 12 and the voltage E2 supplied to the load 13 change as shown in FIG. In the illustrated embodiment, the manner in which the voltage E1 changes with respect to a change in the duty cycle of the switching pulse P is such that the voltage Eb supplied to the load changes in response to a change in the duty cycle of the switching pulse P. ).

Therefore, the voltages El and E2 described above are used to assist components in the device that require voltage change characteristics as shown in FIG. Can be used as t1WX.

If the above-mentioned voltages El and E2 are displayed using a simple voltage display element such as a voltmeter or lamp, the approximate value of the voltage Eb' being supplied to the load, in other words, the current value of the equipment. It is convenient because the operating status can be easily known from the outside.

For example, in the above-mentioned equipment in which the horizontal deflection frequency is variable, the voltage Eb' supplied from the power supply circuit to the load is approximately proportional to the horizontal deflection frequency. Therefore, the voltages El and E mentioned above
If the value of 2 can be read externally, the operating frequency of the device can be easily displayed without the need for a particular frequency conversion circuit.

In particular, if both of the voltages El and E2 mentioned above are displayed with respective lamps, one or both lamps will necessarily light up depending on the level of the horizontal deflection frequency, so it will be difficult to display the operation of one device. It can be used both as a pilot lamp and as a lamp for displaying the horizontal deflection frequency.

FIG. 6 is a circuit diagram in which both of the voltages El and E2 mentioned above are displayed using two-color light emitting diodes. In the figure, 14.15 is a current limiting resistor, 16
is a two-color light emitting diode. Assuming that the two-color light emitting diode 16 is one that emits two colors of light, red and green, for example, R in the figure is the anode of the red light emitting diode.

G corresponds to the anode of the green light emitting diode.

The circuit arrangement shown in FIG. 6 is used as a display circuit for the above-mentioned variable horizontal deflection frequency equipment, and the voltage Eb'' supplied to the load when the horizontal deflection frequency of the equipment is low.
When is low, the red light emitting diode will emit light mainly, and as the horizontal deflection frequency gradually increases, the red light emitting diode will dim and the green light emitting diode will gradually become stronger instead. The voltages El and E2 are set so that the light emitting diode mainly emits green light near the upper limit of the horizontal deflection frequency, that is, when the voltage Eb' supplied to the load is at its highest value. Then, as the horizontal deflection frequency in the device changes from a low state to a high state, the two-color light emitting diode will emit light continuously in the following order: red light → orange light → yellow light → yellow-green light → green light. Since the operating frequency of the device can be displayed using one two-color light emitting diode, the two-color light emitting diode can also function as a pilot lamp.

(Effects) As is clear from the above detailed explanation, the power supply circuit of the present invention includes a means for controlling the opening and closing of power supplied from a DC power supply by a switching element whose opening and closing is controlled by a switching pulse, and a means for controlling the opening and closing of power supplied from a DC power supply by a switching element that is controlled to open and close by a switching pulse. A diode connected between the output side of the switching element and the DC power supply with a connection polarity that makes it conductive when it is cut off.

A switching device comprising an inductor provided between the output side of the switching element and the load, and the voltage applied to the load can be controlled by changing the ratio between the conduction time and the cutoff time of the switching element. [In one circuit, the inductor described above is provided with an auxiliary winding that is electromagnetically coupled to the winding of the inductor, and the rectangular wave voltage generated in the auxiliary winding of the inductor is used. Since this is a power supply circuit that uses half-wave rectification to generate a voltage that fluctuates depending on the ratio of the conduction time and cut-off time of the switching element, the power supply circuit of the present invention uses the main output from the In equipment that uses a switching regulator that can be varied depending on the purpose, the variation occurs in the same direction as the switching regulator's main output variation, or in the opposite direction to the switching regulator's main output variation direction. auxiliary f1g can be easily obtained, and by indicating the voltage with an appropriate indicating element, I
It is also possible to easily display the operating status of the A-device.

[Brief explanation of drawings]

FIG. 1 is a circuit diagram of an embodiment of the power supply circuit of the present invention, FIGS. 2 to 4 are waveform diagrams for explanation, FIG. 5 is a characteristic side diagram for explanation, and FIG. 6 is a power supply of the present invention. A circuit diagram of a part of the circuit, FIG. 7, is a circuit diagram of a conventional example. DC5...DC power supply, SVE...Switching element, IT...Inductor, D, 8.9...Diode, L...Load, C, 10, 11...Capacitor,
ClIC... Choke coil, 5... Inductor primary winding, 6... Inductor secondary winding, 7... Inductor tertiary winding, 14, Is... Current limiting resistor ,

Claims (1)

[Scope of Claims] 1. A means for controlling the opening and closing of power supplied from a DC power supply by a switching element whose opening and closing are controlled by a switching pulse, and a connection polarity such that the switching element is in a conductive state when it is in a cut-off state. A diode connected between the output side of the switching element and a DC power supply, and an inductor provided between the output side of the switching element and the load, and the ratio between the conduction time and the cut-off time of the switching element is determined. In a power supply circuit that includes a switching regulator that can control the voltage applied to the load by changing the voltage, an auxiliary winding that is electromagnetically coupled to the winding of the inductor described above is provided. A power supply circuit as an auxiliary power supply that half-wave rectifies the rectangular wave voltage generated in the auxiliary winding of the inductor and generates a voltage that fluctuates according to the ratio of the conduction time and cut-off time of the switching element. 2. The power supply circuit 3 according to claim 1, which is provided with a display mechanism that displays the magnitude of the voltage of the auxiliary power supply, and a voltage that varies in direct proportion to the conduction time and cutoff time of the switching element from the auxiliary power supply. , a power supply circuit 4 according to claim 1, which generates voltages that vary in inverse proportion to the ratio of conduction time and cutoff time of a switching element, and lights up a light emitting element by each of the voltages. , a power supply circuit according to claim 3, using a two-color light emitting element as a light emitting element.