JP2517397B2 - Multi-transform converter - Google Patents

Description

TECHNICAL FIELD The present invention relates to a power supply device having a plurality of transformers, and particularly in the case of stabilizing an output voltage by using a mag-amplifier (saturable reactor) on a secondary output side. Regarding improvement.

<Prior art> Switching power supplies are, for example, “High-frequency swit”.
As described in "ching power supplies" Chryssis George (1984), there are three types of flyback type, forward type and push-pull type. Of these, the push-pull type is a combination of two forward types. Then, they are operated alternately.

FIG. 5 is a circuit diagram of a push-pull type power supply device, and here shows a multi-output type having a plurality of output terminals of a main output E ₀₁ and a slave output E ₀₂ . In the figure, the converter has two transformers T1 and T2, and ON / OFF control is performed by common switching elements Q1 and Q2. The primary side of the transformer T1, T2, the DC voltage V _in is applied, the collector terminal and the emitter terminal in the case of input-output terminals (the transistor of the switching elements Q1, Q2, the source terminal and the drain terminal in the case of FET Are connected in series, and capacitors C1, C2 and C3, C4 connected in series are connected in parallel. The primary winding n11 of the transformer T1 has one end connected to the intermediate connection point between the switching elements Q1 and Q2 and the other end connected to the capacitor C.
It is connected to the intermediate connection point of 3, C4. The primary winding n21 of the transformer T2 has one end connected to the intermediate connection point between the switching elements Q1 and Q2 and the other end connected to the intermediate connection point between the capacitors C1 and C2.

The secondary winding n12 of the transformer T1 has a center tap, both ends of which are commonly connected via diodes D11 and D12, and the choke coil L11 removes high frequency components and smoothes them by the capacitor C11. The output voltage E ₀₁ is obtained. The main output voltage E ₀₁ is controlled by a main output stabilization circuit (not shown) so that the switching device Q1, Q
A switching control signal is sent to the second control terminal (base terminal for transistor, gate terminal for FET).

The secondary winding n22 of the transformer T2 has a center tap, and one end thereof has a saturable reactor SR21 and a diode D21.
Through the other end of the saturable reactor SR22 and diode D2.
Commonly connected via 2, the high frequency component is removed by the choke coil L21 and smoothed by the capacitor C21, and the slave output voltage E ₀₂ is obtained. The center tap and the common connection point of the diodes D21 and D22 are connected using a diode D23. A control signal is sent to the control terminals of the saturable reactors SR21 and SR22 so that the secondary output voltage E ₀₂ becomes a predetermined voltage by a mag amplifier circuit (not shown).

The operation of the apparatus thus configured will be described below. FIG. 6 is a waveform diagram for explaining the switching state of the device of FIG. 5, (A) is the voltage VA generated at the point A of the secondary winding n12,
(B) is the voltage VB generated at the common connection point B of the diodes D11 and D12. The main output stabilization circuit has a normal pulse width (P
The WM) control circuit generates a rectangular on / off waveform. The mag-amplifier circuit, which is a secondary output stabilizing circuit, generates a transient voltage while the switching element Q is off.
In other words, during the off period of the switching elements Q1 and Q2,
A phenomenon occurs in which the energy stored in the transformers T1 and T2 is released and energy is exchanged between the transformers. Therefore, the "voltage rebound phenomenon" appears during the off period.

<Problems to be Solved by the Invention> However, since the transient voltage caused by the mag-amplifier circuit is rectified and smoothed and used as a part of the energy of the main output voltage E ₀₁ , the pulse width output by the PWM control circuit is changed. It is narrower than when there is no output circuit. Then, there is a problem in that this influence affects the secondary output circuit, and the original pulse width may be insufficient to output the specified secondary output voltage E ₀₂ .

FIG. 7 is an explanatory diagram of this problem, in which the horizontal axis shows the load current 1 _out of the main output circuit and the vertical axis shows the output voltage E ₀₂ . This phenomenon becomes remarkable when the main output is in the light load state and the slave output is in the heavy load state. As a literature on this phenomenon, for example, HFPC
(High Frequency Power Convertion) ・ APRIL1987PROC
There is EEDINGS p.190.

The present invention solves such a problem, and an object thereof is to provide a multi-transformer converter in which the operation of the stabilizing circuit of the slave output circuit does not interfere with the main output circuit.

<Means for Solving the Problems> The present invention which achieves such an object is, as a primary side circuit, a first switching element (Q1) to which a DC voltage (V _in ) is applied to an input terminal, and The output terminal and the input terminal of the switching element of 1 are connected in common, the second switching element (Q2) in which the common and the output terminal are connected, and one end is connected to the common connection point of these switching elements,
A first primary winding (n11), the other end of which is connected to the DC voltage applying unit via a first capacitor (C1) and is connected to the common via a second capacitor (C2); Is connected to a common connection point of these switching elements, and the other end is connected to a DC voltage applying unit via a third capacitor (C3) and is connected to the common via a fourth capacitor (C4). And a second primary winding (n21).

Further, as a secondary circuit for the main output, the main output that supplies a DC voltage (E ₀₁ ) by rectifying and smoothing the switching signal generated in the secondary winding (n12) corresponding to the first primary winding. And a main output stabilizing circuit for supplying a pulse width control signal for stabilizing the output voltage of the main output circuit to a predetermined voltage to the push-pull type first and second switching elements. .

Further, as a secondary circuit for the secondary output, the secondary output for supplying a DC voltage (E ₀₂ ) by rectifying and smoothing the switching signal generated in the secondary winding (n22) corresponding to the second primary winding. It has a circuit and a secondary output stabilizing circuit which supplies a mag-amplifier signal for stabilizing the output voltage of the secondary output circuit to a predetermined voltage to a saturable reactor mounted on the secondary winding.

A means for insulating mutual interference of the transformer is provided between the common connection point of the first and second switching elements and the first and second primary windings.

<Operation> Each component of the present invention has the following action. The secondary circuit for the main output supplies the pulse width control signal to the switching element of the primary circuit so that the main output has a predetermined voltage. The secondary circuit for secondary output supplies the magamplifier signal to the saturable reactor so that the secondary output has a predetermined voltage, but the energy originally supplied to the secondary output circuit is determined by the main output circuit. ing. Therefore, by providing insulating means,
The operation of the slave output stabilizing circuit is prevented from affecting the main output circuit, and the pulse width is maintained as wide as in the case without the slave output circuit. However, since the sub output circuit is supplied with a sufficient pulse width signal, the sub output voltage does not drop even when the main output is in a light load state.

<Embodiment> FIG. 1 is a circuit diagram showing an embodiment of the present invention. Incidentally, in FIG. 1, those having the same functions as those in FIG. In the figure, PWM is a control circuit that stabilizes the main output voltage E ₀₁ and sends a control signal to the control terminals of the switching elements Q1 and Q2, the waveform of which corresponds to the push-pull type. CTL is the secondary output voltage E ₀₂
A mag-amp circuit that stabilizes
The same control signal is sent to the saturable reactor SR21 via D25 and the saturable reactor SR2 via diode D26.
Send to 2.

The diodes D1 to D4 insulate mutual interference between the transformers T1 and T2. The diode D1 has an anode side connected to the output terminal of the switching element Q1 and a cathode side connected to the primary winding n11. The diode D1 has an anode side connected to the output terminal of the switching element Q1 and a cathode side connected to the primary winding n12. The anode side of the diode D3 is connected to the connection portion of the cathode side of the diode D1 and the primary winding n11, and the cathode side is connected to the input terminal of the switching element Q2. The anode side of the diode D4 is connected to the connection portion of the cathode side of the diode D2 and the primary winding n21, and the cathode side is connected to the input terminal of the switching element Q2.

The operation of the apparatus thus configured will be described below. FIG. 2 is a waveform diagram for explaining the switching state of the device of FIG. 1, (A) is a voltage VA generated at point A of the secondary winding n12,
(B) is the voltage VB generated at the common connection point B of the diodes D11 and D12. The main output stabilization circuit has a normal pulse width (P
The WM) control circuit generates a rectangular on / off waveform. The mag-amp circuit, which is a secondary output stabilization circuit, operates while the switching element Q is off, but the secondary winding n2 on the main output side is affected by the action of the diodes D1 to D4 that perform the insulating action.
It prevents the occurrence of transient voltage at 1.

FIG. 3 is an explanatory diagram of stabilizing the secondary output voltage, in which the horizontal axis represents the load current I _out of the main output circuit and the vertical axis represents the secondary output voltage E ₀₂ . Even when the main output is in a light load state, the secondary output is stabilized at the predetermined voltage E ₀₂ . This is because the pulse width of the switching signal of the primary winding n21 can be sufficiently secured.

FIG. 4 is an explanatory view of another embodiment of the present invention. Diode D5 cathode side connected to the input voltage V _in applied side,
The anode side is connected to the input side of the switching element Q2. Diode D6 has switching element Q1 on the cathode side
Is connected to the output terminal and the anode side is connected to the common. The diodes D5 and D6 are called reciprocal diodes, and the reset current flows to the primary side when the transformer is off, but this reset current is recovered as energy and used for the next switching to improve energy efficiency. .

The anode side of the diode D27 is connected to the tap provided on the winding between the center tap of the secondary winding n22 and the saturable reactor SR21, and the cathode side is connected to the common connection point of the diodes D21 and D22. The anode side of the diode D28 is connected to the tap provided on the winding between the center tap of the secondary winding n22 and the saturable reactor SR22, and the cathode side is connected to the common connection point of the diodes D21 and D22. The diodes D27 and D28 act to make the operation of the slave output circuit smooth.

With this configuration, more stable operation is performed as the multi-transform converter.

Although the diodes D1 to D4 are shown as the insulating means of the primary side circuit of the transformers T1 and T2 in the above embodiment, the present invention is not limited to this, and other peak absorbing signal absorbing elements may be used. .

<Effects of the Invention> As described above, according to the present invention, the circuit for insulating mutual interference between the transformers is provided in the primary side circuit.
Even if the main output side has a light load, the secondary output voltage is stable.

[Brief description of drawings]

FIG. 1 is a circuit diagram showing an embodiment of the present invention, and FIG.
FIG. 3 is a waveform diagram for explaining the switching state of the device shown in FIG. 3, FIG. 3 is an explanatory diagram for stabilizing the secondary output, FIG. 4 is a circuit diagram of another embodiment of the present invention, and FIG. FIG. 6 is a circuit diagram, FIG. 6 is a waveform diagram for explaining a switching state of the device of FIG. 5, and FIG. 7 is an explanatory diagram of stabilizing the secondary output. C1 to C4 …… Capacitor, D1 to D4 …… Diode (insulating means), n11, n21 …… Primary winding, n12, n22 …… Secondary winding, Q
1, Q2 …… Switching element, SR11, SR21 …… Saturable reactor, T1, T2 …… Transformer.

Claims (2)

(57) [Claims] 1. A first switching element (Q1) to which a DC voltage (V _in ) is applied to an input terminal, an output terminal and an input terminal of the first switching element are commonly connected, and a common terminal and an output terminal are connected. Is connected to the second switching element (Q2), one end of which is connected to the common connection point of these switching elements, and the other end of which is connected to the DC voltage applying unit via the first capacitor (C1) and The first primary winding (n11) connected to the common via the second capacitor (C2), one end connected to the common connection point of these switching elements, and the other end connected the third capacitor (C3). Second primary winding (n21) connected to the DC voltage applying unit via the fourth capacitor (C4) and the second primary winding (n21) connected to the common, and the secondary corresponding to the first primary winding. The switching signal generated in the winding (n12) A main output circuit for supplying a DC voltage (E ₀₁₎ and Nagaretaira smoothing, the first and second switching push-pull pulse-width control signal for stabilizing the output voltage of the main output circuit to a predetermined voltage A main output stabilizing circuit that supplies the element and a secondary output circuit that supplies a DC voltage (E ₀₂ ) by rectifying and smoothing the switching signal generated in the secondary winding (n22) corresponding to the second primary winding. And a secondary output stabilization circuit that supplies a mag-amp signal that stabilizes the output voltage of the secondary output circuit to a predetermined voltage to a saturable reactor mounted on the secondary winding, and a multi-output multi-transformer including In the converter, a multi-transformer is provided between the common connection point of the first and second switching elements and the first and second primary windings for insulating mutual interference of the transformer. Ko Converter. 2. The insulating means includes a first diode (D1) mounted between an output terminal of the first switching element and the first primary winding, and an output of the first switching element. A second diode (D2) mounted between the terminal and the second primary winding, one end of which is connected to the connecting portion of the first diode and the first primary winding and the other end of which is the second switching A third diode (D
3) and a fourth diode (D4) having one end connected to the connection portion of the second diode and the second primary winding and the other end connected to the input terminal of the second switching element. The multi-transform converter according to claim 1, characterized in that