JPS6128445Y2 - - Google Patents

Description

[Detailed Description of the Invention] A power supply circuit as shown in FIG. 1 can be considered as a power supply circuit that can obtain a high voltage from a low voltage power supply without using a step-up transformer.

That is, the negative end of a DC power source 1 made of, for example, a battery is grounded, and the positive end is grounded via a coil 2, a series circuit of a coil 3 and a capacitor 4, and further via the collector/emitter of a switching transistor 5. The connection point between coil 2 and coil 3 is grounded via capacitor 6, capacitor 7 is connected in parallel with the series circuit of coil 3 and capacitor 4, and a diode for forming a DC path is connected in parallel with this series circuit. 8 is connected, a damper diode 9 is connected in parallel with the transistor 5, and the collector of the transistor 5 is grounded via the coil 10 and the capacitor 11.
The connection point between the capacitor 11 and the output terminal 12 is the output terminal 12, and the transistor 5 is switched by a drive pulse of a constant period.

In this case, the inductance of coil 2 is L ₁ ,
The inductance of coil 3 is L _O , and the capacitor 4 is
When the capacitance of capacitor 6 is C _S , the capacitance of capacitor 6 is C _I , and the capacitance of capacitor 7 is C _O , then C _S ≫ C _I , C _O ......(1) L _I C _I ≒L _O C _O ...(2 ) is chosen for the relationship.

In this circuit, when transistor 5 is first turned on, current flows in the order of power supply 1 -> coil 2 -> diode 8 -> transistor 5 -> power supply 1. At this time, the power flowing through the coil 2 is represented by V _I /L _I (3) where the voltage of the power supply 1 is V _I .

Next, when the transistor 5 is turned off, first,
Due to the resonance between the coil 2 and the capacitor 6, a resonant current flows through the coil 2 during a half period of the resonance.
After that, a current flows in the order of coil 2 → power supply 1 → diode 9 → capacitor 4 → coil 3 → coil 2, and capacitor 4 is charged with the polarity with the right side in the figure being positive.

Next, when the transistor 5 is turned on again, the diode 8 is turned off due to the charging voltage of the capacitor 4, and current flows in the order of the coil 2 -> the coil 3 -> the capacitor 4 -> the transistor 5 -> the power source 1 -> the coil 2.

Furthermore, when the transistor 5 is turned off, due to the resonance between the coil 3 and the capacitor 7, a resonant current flows through the coil 3 for a period of half the resonance period, and then a current flows through the diode 9 as described above. Repeat the above action.

In this way, in a steady state, a sawtooth wave current flows through the coil 3, as shown in FIG. In this case, since the same current as the current flowing through the coil 2 flows through the coil 3, the amplitude of the sawtooth wave current flowing through the coil 3 becomes V _I /L _I T _S (4).

The reactive power that causes this much current to flow through the coil 3 is stored in the capacitor 4 as a voltage value L _O /L _I V _I , so the output terminal 1
2, a DC output voltage of V _O = (1+L _O /L _I )V _I ...(5) is taken out, and the transistor 5
The magnitude of the pulse obtained at the collector of is (1+π/2·T _S /T _R )V _O ...(6).

Note that this power supply circuit is configured as a horizontal deflection circuit for a television receiver, and coil 3
is a horizontal deflection coil, capacitor 4 is an S-shaped correction capacitor, coil 10 is the primary side of a flyback transformer, transistor 5 is supplied with a drive pulse with a horizontal period, T _H is a horizontal period, and T _R is the horizontal blanking period, and T _S is the horizontal scanning period.

When configured as a horizontal deflection circuit in this way,
As shown in equation (4), the horizontal deflection current does not depend on the inductance L _O of the horizontal deflection coil 3;
By reducing the inductance L _I of
A sufficiently large amplitude can be obtained even at low input voltages.

Note that in the above-described circuit, a switching current flows through the power supply 1. For this reason, there is no problem when the power source 1 is a battery, but a problem occurs when the power source 1 includes an output transistor such as a stabilization circuit. In such a case, as shown in FIG.
It is sufficient if the capacitor 15 is connected to the power source so that the capacitor 15 functions as a power source. In this case, capacitor 15
The capacitance is set to a value that does not affect the resonance caused by the coil 2 and capacitor 6.

By the way, in the above circuit, the output current voltage V _O
As is clear from equation (5), can be changed by the ratio of the inductance L _I of the coil 2 to the inductance L _O of the coil 3.

This invention focuses on this point and stabilizes the output voltage using the above-mentioned circuit with a simple configuration.

In this invention, the coil ₂
Alternatively, the inductance L _I or L _O of 3 can be changed.

FIG. 4 shows one example of this, where the inductance L _I of the coil 2 can be changed. That is, the coil 2 is composed of a coil 2a having a constant inductance and a controlled coil 16a of the saturable reactor 16, and the transistor 1 as a variable impedance element is connected to the control coil 16b of the saturable reactor 16.
On the other hand, the output voltage V _O obtained at the output terminal 12 is divided by the voltage dividing circuit 18, and the divided voltage is supplied to the negative input terminal of the comparator amplifier 19, and the Zener diode 20 A constant reference voltage is supplied to the positive input terminal of the comparator amplifier 19, and the output of the comparator amplifier 19 is supplied to the transistor 17 through the amplifier 21.

Therefore, when the output voltage V _O increases, the output of the comparison amplifier 19 decreases, the output of the amplifier 21 decreases, the impedance of the transistor 17 increases, and the saturable reactor 1
The current flowing through the control coil 16b of No. 6 becomes smaller, and the inductance L of the controlled coil 16a decreases.
_IV becomes larger, and therefore the inductance L _I of the entire coil 2 also becomes larger, and the output voltage V _O is reduced. Conversely, when the output voltage V _O decreases, the output of the comparison amplifier 19 increases, the impedance of the transistor 17 decreases, the current flowing through the control coil 16b increases, and the current flowing through the controlled coil 16b increases. As a result, the inductance L _IV of the controlled coil 16a becomes smaller, and therefore the inductance L _I of the entire coil 2 also becomes smaller, so that the output voltage V _O is increased.

Therefore, even if the voltage V _I of power supply 1 fluctuates,
A constant output voltage V _O can always be obtained.

FIG. 5 shows another example in which the inductance L _O of the coil 3 is changed. That is, the coil 3 is composed of a coil 3a having a constant inductance and a controlled coil 16a of the saturable reactor 16, but, for example, the amplifier 21 is composed of the comparative amplifier 1.
The output of 9 is inverted.

Therefore, the inductance L _OV of the controlled coil 16a is changed, the inductance L ₀ of the entire coil 3 is changed, and the output voltage V ₀ is regulated as in the example of FIG. 4.

Note that the diode 8 may be connected in parallel with the capacitor 4. Furthermore, since this is for forming a DC path, a coil with large resistance or reactance may be used. Furthermore, the capacitor 7 may be connected in parallel with the coil 3.

Note that the coil 10 is the primary side of the transformer,
A rectifier circuit may be connected to the secondary side, from which an output voltage is taken out, and the inductance L _I or L _O of the coil 2 or 3 may be changed according to this output voltage.

According to this invention, a high voltage can be obtained from a low voltage power supply without using a step-up transformer, and the output voltage of this high voltage can be easily regulated. Moreover, there is less loss,
Unlike switching-type regulated power supply circuits, it does not emit interference waves.

[Brief explanation of drawings]

Figures 1 and 2 are connection diagrams of an example of a power supply circuit to which this invention is applied, Figure 3 is a waveform diagram for explanation, and Figures 4 and 5 are examples of a regulated power supply circuit according to this invention. FIG. 1 is a DC power supply, 2 is a first coil, 3 is a second coil, 4 is a first capacitor, 6 is a second capacitor, 7 is a third capacitor, and 16 is a saturable reactor.

Claims (1)

[Scope of utility model registration request] One end of the DC power source is connected to the other end of the DC power source via the controlled coil of the saturable reactor, through a series circuit of a deflection coil and an S-shaped correction capacitor, and further via a switching element, and is connected to the controlled coil of the saturable reactor. A connection point with the series circuit is connected to the other end of the DC power supply via another capacitor, another capacitor is connected in parallel with the series circuit or the deflection coil, and the series circuit or the S
An element for forming a DC path is connected in parallel with the DC path correction capacitor, and a damper diode whose conduction direction is reversed is connected in parallel with the switching element, and the switching element is switched so that the DC path is formed from the output side of the switching element. A constant voltage is drawn out that is higher than the voltage of the DC power source, and a control current that changes according to the DC output voltage is supplied to the control coil of the saturable reactor to stabilize the DC output voltage. power supply circuit.