JPS627367A - Dc-dc converter of 1-transistor system - Google Patents

Abstract

PURPOSE:To even output current and miniaturize the second coil on the output side, by adsorbing ripple due to the difference between the values of the first coil and the second coil, with a condenser. CONSTITUTION:When a transistor Tr2 is turned OFF, then input current i3 is reduced because energy is stored in a coil L3 and transformer T1, and by the energy stored in a power source and the coil L3, electric change is stored in a condenser C3, and the energy is loaded back to a winding n2 via the winding n1 of the transformer T1 and is average-value-rectified with diodes D1, D2 and a coil L4, and during the period, the exciting energy of the transformer T1 is also fed from the winding n2 to a load, and the energy is fed to the load with current i6. In this manner, the output side is full-wave-rectified, and so the inductance of the coil L4 may be smaller than conventional choke coil patterns.

Description

[Detailed Description of the Invention] [Summary] In a single-stone DC-DC converter that has coils at the input section and the output section and reduces input/output ripple current,
The output side can be full-wave rectified, allowing the output side coil to be made smaller.

[Industrial application field]

The present invention relates to an improvement of a single-stone DC-DC converter used in electronic communication equipment, etc., which has coils at the input section and the output section and reduces input/output ripple current.

In the above-mentioned single-stone DC-DC converter, it is desired that the output side be capable of full-wave rectification and further that the coil be miniaturized.

[Conventional technology]

The basic circuit of a single-stone DC-DC converter includes a pack boost circuit and a forward circuit.Since the pack boost circuit has no coils on both the input and output sides, a large ripple current flows between the input and output, and the forward circuit has no coils on the output side. There is a coil on the output side, so the current on the output side is continuous, but there is no coil on the input side, so a large ripple current flows on the input side.

For this reason, there is a conventional Chuuk converter that has a coil on the input and output sides so that both input and output currents are continuous.

Figure 5 is a circuit diagram of a conventional Chuuk converter, Figure 6 is an equivalent circuit diagram of Figure 5, and (A) is a transistor 'I'.
When r1 is on, (B) is when the transistor Tri is off, and FIG. 7 is a time chart of waveforms at various parts in FIG.

In the diagram, LL and L2 are coils, C1 and C2 are capacitors, and T
is a transformer, D is a diode, and Tri is a switching transistor.

To explain the operation, when a clock pulse for turning on and off the transistor Tri is input, the transistor Tri is turned on and off, and the voltage VCE between the collector and emitter of the transistor Tri changes as shown in FIG. 7(A).

When the transistor Tri is on, the equivalent circuit shown in FIG. 6(A) is formed, and energy is stored in the coil L1 by the current from the power supply, while the charge stored in the capacitor C1 is transferred via the transformer T and then to the capacitor. Together with the charge stored in C2, energy is stored in coil L2 and the energy is supplied to the load.

When the transistor Tri is turned off, the equivalent circuit shown in FIG. 6(B) is formed, and the energy/L/Gy stored in the power supply and the coil L1 is used to convert the capacitor CI.

Charge is stored in C2, while the energy stored in coil L2 is supplied to the load.

Therefore, when the transistor Tri is turned on and off, the current 11 from the power supply and the current 12 to the load become continuous currents as shown in FIGS. 7(B) and 7(C) because of the presence of the coils L1 and L2.

[Problem that the invention seeks to solve]

However, since this Chuuk converter cannot perform full-wave rectification on the output side, in order to reduce the ripple, the inductance of the coil L2 must be made thicker, resulting in a problem of larger size.

[Means for solving problems]

The above problem is solved by the input power supply and transformer T in Figure 1.
A first coil L3 connected between one end of the primary winding of
, a switch Tr2 connected between the connection point of the first coil L3 and the primary winding and the other end of the primary winding, and a full-wave rectifier circuit connected in parallel to the secondary winding of the transformer. , by the one-stone DC-DC converter of the present invention, which has a capacitor C4 connected in parallel to the full-wave rectifier circuit and a second coil L4 connected in series on the output side of the full-wave rectifier circuit. resolved.

[Effect]

In the present invention, the input terminal of the converter is made continuous by the first coil L3, and the output current is made continuous by the full-wave rectifier circuit and the coil L4. Also, since the values of coil L3 and coil L4 are determined by the magnitude of the current, coils L3 and L
Since the values of 4 are different, ripples occur. In the present invention, the capacitor C4 absorbs the ripple caused by the difference in value between the coils L3 and L4, thereby flattening the output current and making it possible to downsize the second coil L4 on the output side.

〔Example〕

Fig. 1 is a circuit diagram of an embodiment of the present invention, Fig. 2 is an equivalent circuit of Fig. 1, and (A) is when transistor Tr2 is on (B)
is when the transistor Tr2 is off, and FIG.
It is a time chart of the waveform of each part of a figure.

In the figure, L3. L4 is a coil, C3 and C4 are capacitors,
T1 is a transformer, D1 to D3 are diodes, and Tr2 is a switching transistor.

To explain the operation, when a clock pulse that turns on and off the transistor Tr2 is input, the transistor Tr2 turns on and off, and the VCE of the transistor Tr2 becomes as shown in FIG. 3(A).
It changes as shown in .

When the transistor Tr2 is on, the equivalent circuit becomes as shown in FIG. 2(A), the power supply voltage is applied to the coil L3, the input current i3 increases as shown in FIG. 3(B), and energy is generated in the coil L3. can be stored.

In addition, the charge accumulated in the capacitor C3 with the polarity shown in FIG. 2(A) is converted to the n3 winding via the n1 winding of the transformer T1, and is rectified to an average value by the diode D3 and coil L4. Energy is supplied to the load at the current i5 shown in D).

Also, excitation energy is supplied to the transformer T1 during this period.

When the transistor Tr2 is turned off, the equivalent circuit becomes as shown in FIG. 2(B), and since energy is stored in the coil L3 and the transformer T1, the input current i3 decreases as shown in FIG. 3(B), and the power supply The energy stored in the coil L3 accumulates charge in the capacitor C3, and the energy is converted to the n2 winding through the nil wire of the transformer T1, and the energy is converted to the n2 winding through the nil wire of the transformer T1. The average value is rectified by the coil L4, and during this period, the excitation energy of the transformer T1 is also supplied to the load from the N2 winding, supplying energy to the load at a current i6 as shown in FIG. 3(E).

During the period when the transistors T and r2 are off, the difference between the current i6 and the current i4 is absorbed by the capacitor C4 and becomes the current i4.
are made continuous as shown in FIG. 3(C).

In this way, since the output side is full-wave rectified, the inductance of the coil L4 is smaller than that of the conventional Chuke converter, and the coil L4 can be made smaller.

FIG. 4 is a circuit diagram of another embodiment of the present invention.

In the figure, T2 is a transformer, D4. D5 indicates a diode,
The same reference numerals indicate the same functions throughout the figures.

The difference in FIG. 4 from the case in FIG. 1 is that the secondary winding of the transformer T2 is one, and the diode DI is used.

D3. D4.05 is bridge-connected to enable full-wave rectification, and the transformer windings have been changed from 3 to 2, and the operation and characteristics are the same.

〔Effect of the invention〕

As explained in detail above, according to the present invention, since full-wave rectification is performed on the output side, there is an effect that the coil on the output side can be made smaller.

[Brief explanation of drawings]

Fig. 1 is a circuit diagram of an embodiment of the present invention, Fig. 2 is an equivalent circuit of Fig. 1, Fig. 3 is a time chart of waveforms of each part of Fig. 1, and Fig. 4 is another embodiment of the invention. FIG. 5 is a circuit diagram of a conventional Chuke converter, FIG. 6 is an equivalent circuit diagram of FIG. 5, and FIG. 7 is a time chart of waveforms at various parts of FIG. 5. In the figure, L1 to L4 are coils, T, Tl, and T2 are transformers, Cl-C4 is a capacitor, D, Di to D5 are diodes, and Tri and Tr2 are switching transistors. 0-111--------------- (c)72～
--Hehe.

Claims (1)

[Claims] A first coil (L3) connected between the input power source and one end of the primary winding of the transformer (T1);
3), a switch (Tr2) connected between the connection point of the primary winding and the other end of the primary winding, a full-wave rectifier circuit connected in parallel to the secondary winding of the transformer, and a full-wave rectifier circuit connected in parallel to the secondary winding of the transformer; A single-stone type DC/DC characterized in that the output side of the rectifier circuit has a capacitor (C4) connected in parallel to the full-wave rectifier circuit and a second coil (L4) connected in series. converter.