JP2014220995A - Power supply circuit - Google Patents

Abstract

A power supply circuit capable of improving cross regulation between a plurality of output terminals is provided. A transformer having a plurality of output windings Ns1-1, Ns1-2, and Ns2 coupled to each other, and at least a pair of outputs among the plurality of output windings Ns1-1, Ns1-2, and Ns2. One end of the same poles of the windings Ns1-2 and Ns2 where both windings have the same number of turns are connected via a capacitor Ccross, and the other end is electrically directly connected. [Selection] Figure 3

Description

  The present invention relates to a power supply circuit, and more particularly to a power supply circuit with improved cross regulation.

  In the switching power supply, the output voltage is constantly monitored and compared with a reference voltage by an error amplifier, and the output of the power supply circuit is controlled so that a correct voltage is always output. Here, in the case of a switching power supply (multi-output power supply) having a plurality of output terminals, there is a problem that if one output is monitored for stabilization, the stability of the other cannot be maintained. In particular, when a load change occurs on the output side where the stabilization is monitored, a stable output cannot be maintained due to interference with another output sharing the primary winding. In a multi-output power supply, appreciation of a voltage fluctuation on one output side as a voltage on another output is called cross regulation. This cross regulation is one of the common problems with multi-output power supplies. For the determination of “cross regulation”, the fluctuation rate of the actual voltage value with respect to the changing reference voltage value of the output terminal is used.

  Switching power supply devices having two or more output terminals are widely used. However, it is widely known that the voltage fluctuation rate may deteriorate if there is a large difference in the power extracted from the output terminal. FIG. 1 shows a general flyback type two-output power supply device 1. The power supply device 1 includes a primary coil Np, a first output coil (secondary coil) Ns1 and a second output coil (secondary coil) Ns2 that are coupled to each other, and a switching element Q1 that is connected in series with the primary coil Np. A control circuit Ic (not shown) for controlling the switch element Q1, a rectifier element (diode) D1 for supplying power to the first output terminal Vo1, and a power for supplying power to the second output terminal Vo2 And a rectifying element (diode) D2.

  In such a power supply device 1, it is common to monitor (feedback control) the voltage of one output terminal Vo1 and adjust the duty of the switching transistor Q1 so that the voltage value becomes stable. The other output terminal Vo2 is not normally monitored (feedback control). As a result, if there is a large difference in the output power at each output end, the voltage fluctuation rate at the output end that is not feedback controlled may increase.

  In the circuit shown in FIG. 1, the first output terminal Vo1 = 10V (with feedback control) and the load is 0.1A to 20A. The second output terminal Vo2 = 5 V (no feedback control), and the load is 5 A (fixed). At this time, the fluctuation value of the output voltage is shown in FIG. As can be seen from FIG. 2, Vo2 was very unstable, and there was a large fluctuation in the range of 3V to 6V.

  In order to suppress such deterioration of the voltage fluctuation rate, a measure is taken to stabilize the load by artificially increasing the load with a dummy resistor or the like, but in this case, deterioration of the conversion efficiency is unavoidable.

  The present invention has been made to solve the above-described problems, and an object of the present invention is to provide a power supply circuit that suppresses deterioration of conversion efficiency and improves the voltage fluctuation rate.

  The power supply circuit of the present invention is a power supply circuit having multiple output terminals, and includes a transformer having a plurality of output windings coupled to each other, and at least a pair of output windings among the plurality of output windings. In this case, one end of the same poles of the portions where both windings have the same number of turns are connected via a capacitor (cross capacitor), and the other end is electrically connected. According to such a configuration, it is possible to improve the cross regulation between the plurality of output terminals and reduce the voltage fluctuation rate.

  In the power supply circuit of the present invention, the other end of the portion of the at least one pair of output windings that both have the same number of turns may be directly connected. Furthermore, in the power supply circuit of the present invention, at least one of the at least one pair of output windings may have the same number of turns as the other output winding by adding an intermediate tap or an additional winding. According to such a configuration, the cross capacitor can be easily connected to various power supply circuits, and the cross regulation can be improved.

  Further, the power supply circuit of the present invention includes at least two output windings coupled to each other, and each of the two output windings has the same number of turns and an intermediate tap from the same polarity portion. It is also possible to connect the two intermediate taps through a cross capacitor. According to such a configuration, it is possible to easily form a power supply circuit with good two-output cross regulation.

  Further, in the power supply circuit of the present invention, the first output winding includes a transformer having a first output winding, a second output winding, and a third output winding coupled to each other. The number of turns of either the second output winding or the third output winding is the same, and the first intermediate tap is pulled out from the same polarity portion, and the same polarity portion of the one output winding is set to the first polarity. A second intermediate tap that is the same number as the number of turns of the other output winding and that has the same polarity, and the same polarity portion of the other output winding is The connection is made through two cross capacitors. According to such a configuration, it is possible to easily form a power supply circuit with good three-output cross regulation.

  The power supply circuit according to the present invention further includes a transformer having three output windings coupled to each other, each of the three output windings having the same number of turns and having the same polarity. An intermediate tap is drawn out from any of the three connection methods for connecting the intermediate taps, and the intermediate taps are connected via a cross capacitor. According to such a configuration, it is possible to easily form a power supply circuit with good three-output cross regulation.

  In the power supply circuit of the present invention, at least one of the plurality of output windings is feedback controlled. According to such a configuration, the voltage fluctuation rate of the output terminal that is not feedback-controlled can be reduced, and the cross regulation can be improved.

  In the power supply circuit of the present invention, the power supply circuit is a flyback or forward switching power supply circuit. According to such a configuration, the cross capacitor can be connected to each type of power supply circuit, and cross regulation can be improved.

  In the power supply circuit of the present invention, the plurality of output windings are output inductors. According to such a configuration, the cross capacitor can be connected between the same number of turns of the output inductor, and the cross regulation can be improved.

  According to the power supply circuit of the present invention, the cross regulation of the power supply circuit can be improved only by adding a normal capacitor element without greatly changing the configuration of the power supply circuit.

It is a figure which shows the power supply device 1 which is a flyback of a prior art, and has two output terminals. It is a graph of the output voltage of the power supply device 1 shown in FIG. 1 is a diagram showing a power supply circuit 100 according to a first embodiment of the present invention. FIG. 4 is an equivalent circuit diagram when the power supply circuit shown in FIG. 3 operates. It is a figure which shows the effect _| action of the cross capacitor _Ccross in the power supply circuit 100 shown in FIG. It is a figure which shows the effect _| action of the cross capacitor _Ccross in the power supply circuit 100 shown in FIG. 4 is a graph of the output voltage of the power supply circuit 100 shown in FIG. It is a figure which shows the power supply circuit 200 which concerns on the 2nd Embodiment of this invention. It is a figure which shows the power supply circuit 201 which is a modification of the 2nd Embodiment of this invention. It is a figure which shows the power supply circuit 202 which is a modification of the 2nd Embodiment of this invention. It is a figure which shows the power supply circuit 300 which concerns on the 3rd Embodiment of this invention. It is a figure which shows the power supply circuit 400 which concerns on the 4th Embodiment of this invention. It is a figure which shows the power supply circuit 500 which concerns on the 5th Embodiment of this invention. It is a figure which shows the power supply circuit 600 which concerns on the 6th Embodiment of this invention. FIG. 13 is an equivalent circuit diagram when the power supply circuit 600 shown in FIG. 12 operates. It is a figure which shows the power supply circuit 700 which concerns on the 7th Embodiment of this invention. It is a figure which shows the power supply circuit 800 which concerns on the 8th Embodiment of this invention. It is a figure which shows the power supply circuit 900 which concerns on the 9th Embodiment of this invention. It is a figure which shows the power supply circuit 1000 which concerns on the 10th Embodiment of this invention. It is a figure which shows the power supply circuit 1100 which concerns on the 11th Embodiment of this invention. It is a figure which shows the power supply circuit 1101 which is a modification of the 11th Embodiment of this invention.

  Embodiments of the present invention will be described below with reference to the accompanying drawings. Note that the same reference numerals are used for the same elements, and redundant description is omitted.

[First Embodiment]
FIG. 3 is a circuit obtained by adding the technique according to the present invention to the flyback type 2-output power supply device 1 shown in FIG. 1, and is a diagram showing the power supply circuit 100 according to the first embodiment of the present invention. 3 includes a primary winding Np, a first output winding (secondary winding) Ns1 and a second output winding (secondary winding) Ns2 that are coupled to each other, and a primary winding Np. Switch element Q1 connected in series, control circuit Ic (not shown) for controlling switch element Q1, rectifier element (diode) D1 for supplying power to first output terminal Vo1, and second output And a rectifying element (diode) D2 for supplying power to the end Vo2. Since the winding directions of the primary winding Np and the secondary windings Ns1, Ns2 are reversed, a flyback power supply circuit is configured. Here, in the first output winding Ns1, the intermediate tap Tap101 is pulled out from the portion (node 101) having the same number of turns as the second output winding Ns2, and the same poles of the intermediate tap Tap101 and the second output winding Ns2 are connected to each other. It is connected through a cross capacitor (C _cross ), and the other end (node 102, node 104) is electrically connected directly.

FIG. 4 is an equivalent circuit diagram when the power supply circuit shown in FIG. 3 operates. Here, when a load is connected, a potential difference is generated between both ends of the cross capacitor (C _cross ) due to a difference in load current. A current flows from the output winding on the output circuit side having a high voltage to the output winding side on the output circuit side having a low voltage through the cross capacitor so that the voltage at both ends of the cross capacitor decreases. Assuming that the voltage on the Ns1-2 side is higher than the voltage on the Ns2 side, the leakage inductance (Lf1-2) and winding resistance (R1-2) of Ns1-2 and the leakage of Ns2 in the equivalent circuit diagram (Fig. 4) In consideration of inductance (Lf2) and winding resistance (R2), cross capacitor C _cross current flows in the path of C _cross → R1-2 → Lf1-2 → Ns1-2 → Ns2 → Lf2 → R2 → C _cross. As a result, the difference in output voltage becomes smaller.

5 and 6 are diagrams showing the action of the cross capacitor C _cross in the power supply circuit 100 shown in FIG. Here, for convenience of explanation, the number of turns of the winding Ns1-1 is set to zero. When the first output terminal Vo1 is heavily loaded and the second output terminal Vo2 is lightly loaded, a large current flows through the first output terminal Vo1 and the leakage inductance Lf1-2 exists, so both ends of the leakage inductance Lf1-2 Voltage V _Lf1-2 (V _Lf1-2 = L · dI / dt) increases. As a result, the voltage V _Ns1-2 (V _Ns1-2 = V _Lf1-2 + Vo1) _{across Ns1-2} increases. Accordingly, the voltage of the winding Ns2 increases, and energy is transferred to the second output terminal Vo2. However, since the cross capacitor C _cross is added, in the first state shown in FIG. 5, the cross capacitor C _cross provides a path, and the energy of the winding Ns2 is transferred to the first output terminal Vo1 instead of the second output terminal Vo2. Forward. In the second state shown in FIG. 6, after the energy transfer is finished, the voltage fluctuation of the cross capacitor C _cross due to the energy transfer is automatically balanced by the windings Ns1-2 and Ns2. Therefore, the cross regulation can be improved by the voltage balancing action of the cross capacitor C _cross .

Similarly, when the first output terminal Vo1 is lightly loaded and the second output terminal Vo2 is heavily loaded, the cross capacitor C _cross transfers the remaining energy in the winding Ns1-2 to the second output terminal Vo2. . Therefore, cross regulation is greatly improved.

  FIG. 7 is a graph of the output voltage of the power supply circuit 100 shown in FIG. In the power supply circuit 100 shown in FIG. 3, the first output terminal Vo1 = 10 V (with feedback control) and the load is 0.1A to 20A. The second output terminal Vo2 = 5 V (no feedback control), and the load is 5 A (fixed). At this time, the fluctuation value of the output voltage is shown in FIG. As can be seen from FIG. 7, Vo2 is very stable and is fixed at about 5V. This shows that the cross regulation of the power supply circuit 100 is greatly improved.

In the present embodiment, one output terminal is feedback-controlled and the other output terminals are not feedback-controlled. However, feedback control may be performed using a value obtained by adding the output voltages from the two output terminals at a constant ratio. For example, control may be performed so that the sum of 80% of the voltage value of the first output terminal Vo1 and 20% of the voltage value of the second output terminal Vo2 becomes a specified value. With such a power supply circuit, the cross regulation can be similarly improved by the energy balance effect of the cross capacitor _Ccross .

In the present embodiment, the other end (node 102, node 104) is directly connected via a wire, but a capacitor, a constant voltage source, or a Zener diode is connected between the node 102 and node 104, for example. You may connect via. Well if the winding Ns1-2 and winding Ns2 to a closed loop through the cross capacitor C _cross, wherein a capacitor as an example, a constant voltage source, or to use a zener diode, a node 102 and node 104 This is to provide a relatively stable voltage during the period.

  In the present embodiment, the number of turns of the winding Ns1-1 may be 0. In this case, the power supply circuit 100 has two identical or opposite outputs.

Further, in the present embodiment, with respect to the second output winding Ns2, not drawn an intermediate tap, by adding an additional winding, a cross capacitor C _cross the second output winding Ns2 through the additional winding You may connect. Thus, by adding an additional winding to the second output winding Ns2, the total number of turns of the winding becomes equal to the winding Ns1-2 (or Ns1). In this way, it is possible to obtain the effect of improving the cross regulation almost the same as in the present embodiment.

[Second Embodiment]
FIG. 8A is a diagram showing a power supply circuit 200 according to the second embodiment of the present invention. The power supply circuit 200 according to the second embodiment is different from the first embodiment in that an intermediate tap is drawn together with the first output winding (secondary winding) Ns1 and the second output winding (secondary winding) Ns2. Mainly different from the power supply circuit 100 according to FIG.

The power supply circuit 200 is connected in series with the primary winding Np, the first output winding (secondary winding) Ns1 and the second output winding (secondary winding) Ns2 that are coupled to each other, and the primary winding Np. Switch element Q1, control circuit Ic (not shown) for controlling switch element Q1, rectifier element (diode) D1 for supplying power to first output terminal Vo1, and second output terminal Vo2 And a rectifying element (diode) D2 for supplying electric power. Since the winding directions of the primary winding Np and the secondary windings Ns1, Ns2 are reversed, a flyback power supply circuit is configured. Further, in the first output winding Ns1 and the second output winding Ns2, the intermediate taps Tap201 and Tap202 are drawn from the same number of turns (node 201 and node 203), and the intermediate taps Tap201 and Tap202 are connected to the cross capacitor C _cross. And the other ends (node 202, node 204) are electrically connected.

The power supply circuit 200 has the same operating principle as the power supply circuit 100 shown in FIG. Winding Ns1-2 and winding Ns2-2 is connected to the cross capacitor C _cross. The cross regulation can be improved by the energy balance effect of the cross capacitor C _cross .

In the present embodiment, one output terminal is feedback-controlled and the other output terminals are not feedback-controlled. However, the two output terminals may be feedback controlled in proportion. With such a power supply circuit, the cross regulation can be similarly improved by the energy balance effect of the cross capacitor _Ccross .

In the present embodiment, the other end (node 202, node 204) is electrically directly connected to form a power supply circuit having two plus (+) output ends. May be connected via a capacitor, a constant voltage source, or a Zener diode. A winding Ns1-2 and winding Ns2-2 may if the closed loop via a cross capacitor C _cross.

For example, FIG. 8B is a diagram showing a power supply circuit 201 which is a modification of the second embodiment of the present invention. A power supply circuit having one plus (+) output end and one minus (-) output end is configured by connecting the other end (node 202, node 204) via a capacitor C2. In this modified example, via two capacitors C2, C _cross, constitute a loop in which the winding Ns1-2 and the winding Ns2-2 turns are the same is closed, the voltage difference between the two outputs The cross regulation can be improved.

For example, FIG. 8C is a diagram showing a power supply circuit 202 which is a further modification of the second embodiment of the present invention. The other ends (node 202 and node 204) are each connected to an AC ground to form a power supply circuit having two isolated output ends. In this modification, ground GND, and through a C _cross, constitutes a loop turns is closed and the winding Ns1-2 and winding Ns2-2 the same, reduced text the voltage difference between the two output terminals , Cross regulation can be improved.

  In the present embodiment and its modifications, the number of turns of the winding Ns1-1 and the winding Ns2-1 may be zero. When the number of turns of only the winding Ns1-1 or only the winding Ns2-1 is 0, the configuration is the same as that of the first embodiment. When the winding Ns1-1 and the winding Ns2-1 are 0, the power supply circuit 200 has two identical or opposite outputs.

  Further, the positions of the first output winding Ns1 and the second output winding Ns2 of this embodiment may be exchanged.

[Third Embodiment]
FIG. 9 is a diagram showing a power supply circuit 300 according to the third embodiment of the present invention. In the power supply circuit 300 according to the third embodiment, the second output winding (secondary winding) Ns2 is connected to the first output winding (secondary winding) Ns1 by adding an additional winding. Thus, it is mainly different from the power supply circuit 200 according to the second embodiment.

The power supply circuit 300 is connected in series with the primary winding Np, the first output winding (secondary winding) Ns1 and the second output winding (secondary winding) Ns2 that are coupled to each other, and the primary winding Np. Switch element Q1, control circuit Ic (not shown) for controlling switch element Q1, rectifier element (diode) D1 for supplying power to first output terminal Vo1, and second output terminal Vo2 And a rectifying element (diode) D2 for supplying electric power. Since the winding directions of the primary winding Np and the secondary windings Ns1, Ns2 are reversed, a flyback power supply circuit is configured. In addition, the intermediate tap Tap301 (node 301) is pulled out to the first output winding Ns1, and the additional winding Ns2-add (node 303) is added to the second output winding Ns2, and the winding Ns1-2 The number of turns is configured so that the total number of turns of the winding Ns2 and the winding Ns2-add is equal. In this embodiment, the intermediate tap Tap301 the first output winding Ns1 (node 301) and the second addition output winding Ns2 winding Ns2-the add (node 303) is the same poles through the cross capacitor C _cross The other end (node 302, node 304) is electrically connected.

The operation principle of the power supply circuit 300 is the same as that of the power supply circuit 100 shown in FIG. Winding Ns1-2 and winding (Ns2 + Ns2-add) is connected to the cross capacitor C _cross. The cross regulation can be improved by the energy balance effect of the cross capacitor C _cross .

In the present embodiment, one output terminal is feedback-controlled and the other output terminals are not feedback-controlled. However, the two output terminals may be feedback controlled in proportion. With such a power supply circuit, the cross regulation can be similarly improved by the energy balance effect of the cross capacitor _Ccross .

In this embodiment, the other end (node 302, node 304) is directly connected via a wire, but a capacitor, a constant voltage source, or a Zener diode is connected between the node 302 and node 304. May be connected. Winding Ns1-2 and winding and (Ns2-add + Ns2) may if the closed loop via a cross capacitor C _cross.

In the present embodiment, the additional winding N1-add may be added to the first output winding Ns1, and the number of turns of the winding (Ns1-add + Ns1) and the number of turns of the winding (Ns2-add + Ns2) are Are equal. With such a configuration, the same cross regulation can be improved. In addition, the cross capacitor C _cross , the first output winding Ns1 and the second output winding Ns2 can be obtained by adding an intermediate tap or additional winding, either or both of the first output winding Ns1 and the second output winding Ns2. And the number of turns of the windings at the two output ends are matched.

  Further, the positions of the first output winding Ns1 and the second output winding Ns2 of this embodiment may be exchanged.

[Fourth Embodiment]
FIG. 10 is a diagram showing a power supply circuit 400 according to the fourth embodiment of the present invention. The power supply circuit 400 according to the fourth embodiment is mainly different from the power supply circuit 200 according to the second embodiment in that it is a forward power supply circuit.

The power supply circuit 400 shown in FIG. 10 differs from the power supply circuit 200 according to the second embodiment in the configuration on the secondary winding side. The winding direction of the secondary windings Ns1, Ns2 is reversed from the winding direction of the secondary winding of the power supply circuit 200 of the second embodiment, and the primary winding Np and the secondary windings Ns1, Ns2 The winding direction is the same, and constitutes a forward type power supply circuit. The first output winding Ns1 side includes a rectifying element D3, a rectifying element D4, an inductor Ls1, and a capacitor C1. The second output winding Ns2 side includes a rectifying element D5, a rectifying element D6, an inductor Ls2, and a capacitor C2. Further, in the first output winding Ns1 and the second output winding Ns2, two intermediate taps Tap401 and Tap402 are drawn from the same number of turns (node 401 and node 403), and the intermediate taps Tap401 and Tap402 (node 401) , Node 403) is connected via a cross capacitor C _cross (cross capacitor), and the other ends (node 402, node 404) are electrically connected.

The power supply circuit 400 has the same operating principle as the power supply circuit 200 shown in FIG. 8A. Winding Ns1-2 and winding Ns2-2 is connected to the cross capacitor C _cross. The cross regulation can be improved by the energy balance effect of the cross capacitor C _cross .

In the present embodiment, one output terminal is feedback-controlled and the other output terminals are not feedback-controlled. However, the two output terminals may be feedback controlled in proportion. With such a power supply circuit, the cross regulation can be similarly improved by the energy balance effect of the cross capacitor _Ccross .

In this embodiment, the other end (node 402, node 404) is directly connected via a wire, but a capacitor, a constant voltage source, or a Zener diode is connected between the node 402 and node 404. May be connected. A winding Ns1-2 and winding Ns2-2 may if the closed loop via a cross capacitor C _cross.

  Similarly to the power supply circuit 200 of the second embodiment, the power supply circuit 400 of the present embodiment is directly connected via a wire between the other end (node 402, node 404), and two plus ( +) Configure a power supply circuit having an output terminal. Further, as in the modification of the second embodiment, a capacitor is connected between the other ends (node 402, node 404), and one plus (+) output end and one minus (−) output end are connected. You may comprise the power supply circuit which has. Alternatively, the other end (node 402, node 404) may be connected to the ground via a capacitor to configure a power supply circuit having two isolated output ends. This has the same effect as the modification of the second embodiment.

  In the present embodiment and its modifications, the number of turns of the winding Ns1-1 and the winding Ns2-1 may be zero. When the number of turns of the winding Ns1-1 and the winding Ns2-1 is both zero, the power supply circuit 400 has two identical or opposite outputs.

  Further, the positions of the first output winding Ns1 and the second output winding Ns2 of this embodiment may be exchanged.

Also, output winding Ns2 of the present embodiment, like the third embodiment, may be connected with the cross capacitor C _cross by adding an additional winding.

[Fifth Embodiment]
FIG. 11 is a diagram showing a power supply circuit 500 according to the fifth embodiment of the present invention. The power supply circuit 500 according to the fifth embodiment is mainly different from the power supply circuit 200 according to the second embodiment in that it is a half-bridge type power supply circuit.

  The power supply circuit 500 is connected to the primary winding Np, the first output winding (secondary winding) Ns1 and the second output winding (secondary winding) Ns2 that are coupled to each other, and the primary winding Np. Switching elements Q2 and Q3. The first output winding Ns1 is divided into windings Ns1-1, Ns1-2, Ns1-3, Ns1-4, and the second output winding Ns2 is windings Ns2-1, Ns2-2, Ns2-3, Ns2 Divided into -4.

Among them, the number of turns of the winding Ns1-2, the winding Ns2-2, the winding Ns1-3, and the winding Ns2-3 is the same. Winding Ns1-2 and winding Ns2-2 is connected via a first cross capacitor _C cross501, winding Ns1-3 and winding Ns2-3 is connected via a second cross capacitor _C cross502. Further, the number of turns of the winding Ns1-1 and Ns1-4 or the winding Ns2-1 and Ns2-4 may be zero. In this case, there is no intermediate tap.

The power supply circuit 500 has the same operating principle as the previous power supply circuit 200. Winding Ns1-2 and _Ns2-2 are connected to cross capacitor _Ccross501 . The cross regulation can be improved by the energy balance effect of the cross capacitor C _cross501 . Further, the winding Ns1-3 and the winding Ns2-3 are connected to the cross capacitor _Ccross502 . The cross regulation can be improved by the energy balance effect of the cross capacitor C _cross502 .

In this embodiment, the other end (node 501 and node 502) is directly connected via a wire, but a capacitor, a constant voltage source, or a Zener diode is connected between the node 501 and node 502. You may connect. The winding Ns1-2, the winding Ns2-2, the winding Ns1-3, and the winding Ns2-3 may be a closed loop via the cross capacitors _Ccross501 and _Ccross502 .

[Sixth Embodiment]
FIG. 12 is a diagram showing a power supply circuit 600 according to the sixth embodiment of the present invention. The power supply circuit 600 according to the sixth embodiment is mainly different from the power supply circuit 200 according to the second embodiment in that it has three output terminals.

The power supply circuit 600 includes a primary winding Np, a first output winding (secondary winding) Ns1, a second output winding (secondary winding) Ns2, and a third output winding (two Secondary winding) Ns3, switch element Q1 connected in series with primary winding Np, control circuit Ic (not shown) for controlling switch element Q1, and power for supplying power to first output terminal Vo1 A rectifying element (diode) D1, a rectifying element (diode) D2 for supplying power to the second output terminal Vo2, and a rectifying element (diode) D3 for supplying power to the third output terminal Vo3 are provided. . Since the winding directions of the primary winding Np and the secondary windings Ns1, Ns2, and Ns3 are reversed, a flyback power supply circuit is configured. Further, in the first output winding Ns1, the number of turns of the third output winding Ns3 is the same as the number of turns of the second output winding Ns2, and the intermediate tap Tap602 (node 602) is drawn from the same polarity part. An intermediate tap Tap601 (node 601) is pulled out from the same and same-polarity part, and the intermediate tap Tap601 and the third output winding Ns3, and the intermediate tap Tap602 and the second output winding Ns2 are cross capacitors. _They are connected via C _cross602 and C _cross601 respectively.

FIG. 13 is an equivalent circuit diagram when the power supply circuit 600 shown in FIG. 12 operates. C _cross601 → R1-3 → Lf1-3 → Ns1-3 → Ns2 → Lf2 → R2 path from the output winding on the output circuit side with high voltage to the output winding side on the output circuit side with low voltage through the cross capacitor Thus, a current flows so that the voltage across the cross capacitor C _cross601 decreases, and as a result, the difference in output voltage decreases. Similarly, the voltage across the cross capacitor C _cross602 decreases in the path of C _cross602 → R1-2 → Lf1-2 → Ns1-2 → R1-3 → Lf1-3 → Ns1-3 → Ns3 → Lf3 → R3 Current flows in.

The power supply circuit 600 is the same as the operation principle of the power supply circuit 200. Connect winding (Ns1-2 + Ns1-3) and winding Ns3 to cross capacitor C _cross602 . The cross regulation can be improved by the energy balance effect of the cross capacitor C _cross602 . Further, the winding Ns1-3 and the winding Ns2 are connected to the cross capacitor _Ccross601 . The cross regulation can be improved by the energy balance effect of the cross capacitor C _cross601 .

In the present embodiment, one output terminal is feedback-controlled, and the other two output terminals are not feedback-controlled. However, two output terminals may be feedback-controlled in proportion and the other output terminal may not be feedback-controlled. Alternatively, all three output terminals may be feedback controlled in proportion. With such a power supply circuit, the cross regulation can be similarly improved by the energy balance action of the cross capacitors C _cross601 and C _cross602 .

Further, in the present embodiment, the node 601 and the winding Ns3 and the node 602 and the winding Ns2 are connected to each other via a capacitor, and between the node 603 and the node 605 and between the node 603 and the node 604. Are connected directly via a wire, but may be connected between a node 603 and a node 604, or between a node 603 and a node 605 via a capacitor, a constant voltage source, or a Zener diode. Each winding may be a closed loop via the cross capacitors C _cross601 and C _cross602 .

  In the present embodiment, the number of turns of the winding Ns1-1 may be zero. Such an arrangement is applied to a state where the first output voltage and the second output voltage are equal (for example, both are 12V or ± 12V).

[Seventh Embodiment]
FIG. 14 is a diagram showing a power supply circuit 700 according to the seventh embodiment of the present invention. The power supply circuit 700 according to the seventh embodiment is mainly different from the power supply circuit 600 according to the sixth embodiment in that the position of the intermediate tap is different.

The power supply circuit 700 includes a primary winding Np, a first output winding (secondary winding) Ns1, a second output winding (secondary winding) Ns2, and a third output winding (two Secondary winding) Ns3, switch element Q1 connected in series with primary winding Np, control circuit Ic (not shown) for controlling switch element Q1, and power for supplying power to first output terminal Vo1 A rectifying element (diode) D1, a rectifying element (diode) D2 for supplying power to the second output terminal Vo2, and a rectifying element (diode) D3 for supplying power to the third output terminal Vo3 are provided. . Since the winding directions of the primary winding Np and the secondary windings Ns1, Ns2, and Ns3 are reversed, a flyback power supply circuit is configured. Further, in the first output winding Ns1, the number of turns of the third output winding Ns3 is the same, and the intermediate tap Tap701 is pulled out from the same polarity portion, and in the second output winding Ns2, the third output winding Ns3 The intermediate tap Tap702 is pulled out from the same polarity and the same polarity, and the intermediate tap Tap701 and the third output winding Ns3 and the intermediate tap Tap702 and the third output winding Ns3 are cross capacitors. Connect via C _cross701 and C _cross702 .

The power supply circuit 700 is the same as the operation principle of the power supply circuit 600. Winding Ns1-2 and Ns3 are connected to cross capacitor _Ccross701 . The cross regulation can be improved by the energy balance action of the cross capacitor C _cross701 . Further, the winding Ns2-2 and the winding Ns3 are connected to the cross capacitor _Ccross702 . The cross regulation can be improved by the energy balance effect of the cross capacitor C _cross702 .

In the present embodiment, one output terminal is feedback-controlled, and the other two output terminals are not feedback-controlled. However, two output terminals may be feedback-controlled in proportion and the other output terminal may not be feedback-controlled. Alternatively, all three output terminals may be feedback controlled in proportion. With such a power supply circuit, the cross regulation can be similarly improved by the energy balance action of the cross capacitors C _cross701 and C _cross702 .

In this embodiment, the extremes (nodes 703 and 705) are directly connected via wires, and the nodes 704 and 705 are connected via capacitors. With this configuration, the output terminal has two plus outputs and one minus output. For example, (+ 5V, -12V, + 12V), (+ 5V, -15V, + 15V). Alternatively, the node 703 and the node 705, and the node 704 and the node 705 may be connected via a capacitor, a constant voltage source, or a Zener diode. The winding Ns1-2 and the winding Ns3, or the winding Ns2-2 and the winding Ns3 only _need to form a closed loop via the cross capacitors _Ccross701 and _Ccross702 .

[Eighth Embodiment]
FIG. 15 is a diagram showing a power supply circuit 800 according to the eighth embodiment of the present invention. The power supply circuit 800 according to the eighth embodiment is mainly different from the power supply circuit 600 according to the sixth embodiment in that the numbers and positions of intermediate taps and cross capacitors are different.

  The power supply circuit 800 includes a primary winding Np, a first output winding (secondary winding) Ns1, a second output winding (secondary winding) Ns2, and a third output winding (two Secondary winding) Ns3, switch element Q1 connected in series with primary winding Np, control circuit Ic (not shown) for controlling switch element Q1, and power for supplying power to first output terminal Vo1 A rectifying element (diode) D1, a rectifying element (diode) D2 for supplying power to the second output terminal Vo2, and a rectifying element (diode) D3 for supplying power to the third output terminal Vo3 are provided. . In the three output windings to be coupled, in each of the three output windings, the number of turns is the same, and an intermediate tap is drawn from the same pole portion, and the three intermediate taps Tap801 to 803 ( A capacitor is connected between any two of the nodes 801 to 803). That is, at least one capacitor is connected between any two of the nodes 801, 802, and 803 in the power supply circuit 800.

The power supply circuit 800 is the same as the operation principle of the power supply circuit 600 described above. The winding Ns1-2 and the winding Ns2-2 are connected to the cross capacitor _Ccross801 . The cross regulation can be improved by the energy balance effect of the cross capacitor C _cross801 . Further, the winding Ns2-2 and the winding Ns3-2 are connected to the cross capacitor _Ccross802 . The cross regulation can be improved by the energy balance effect of the cross capacitor C _cross802 . Further, the winding Ns1-2 and the winding Ns3-2 are connected to the cross capacitor _Ccross803 . The cross regulation can be improved by the energy balance effect of the cross capacitor C _cross803 .

In the present embodiment, a capacitor is connected between the extremes (node 804 and node 805), and a capacitor is connected between the extremes (node 805 and node 806). ) Are directly connected via wires. With this configuration, the output terminal has two plus outputs and one minus output. For example, (+ 5V, -12V, + 12V), (+ 5V, -15V, + 15V). Further, the node 804 and the node 805, the node 805 and the node 806, and the node 804 and the node 806 may be connected via a capacitor, a constant voltage source, or a Zener diode. Winding Ns1-2 and winding Ns2-2, winding Ns2-2 and winding Ns3-2, or winding Ns1-2 and winding Ns3-2 are closed via cross capacitors C _cross801 and C _cross802 It only has to be a loop.

[Ninth Embodiment]
FIG. 16 is a diagram showing a power supply circuit 900 according to the ninth embodiment of the present invention. The power supply circuit 900 according to the ninth embodiment is mainly different from the power supply circuit 600 according to the sixth embodiment in that the positions of the intermediate tap and the cross capacitor are different.

The power supply circuit 900 includes a primary winding Np, a first output winding (secondary winding) Ns1, a second output winding (secondary winding) Ns2, and a third output winding (two Secondary winding) Ns3, switch element Q1 connected in series with primary winding Np, control circuit Ic (not shown) for controlling switch element Q1, and power for supplying power to first output terminal Vo1 A rectifying element (diode) D1, a rectifying element (diode) D2 for supplying power to the second output terminal Vo2, and a rectifying element (diode) D3 for supplying power to the third output terminal Vo3 are provided. . In the first output winding Ns1, the number of turns of the second output winding Ns2 is the same as that of the second output winding Ns2, and the intermediate tap Tap901 is pulled out from the same polarity portion, and the intermediate tap Tap901 and the second output winding Ns2 are connected to the cross capacitor C. _Connected via _cross901 , in the second output winding Ns2, the number of turns of the third output winding Ns3 is the same as that of the third output winding Ns3, and the intermediate tap Tap902 and the third output winding are pulled out from the same polarity part. Ns3 is connected via a cross capacitor _Ccross902 .

The power supply circuit 900 is the same as the operation principle of the power supply circuit 600 described above. Windings Ns1-2 and Ns2 are connected to a cross capacitor _Ccross901 . The cross regulation can be improved by the energy balance effect of the cross capacitor C _cross901 . Further, the winding Ns2-2 and the winding Ns3 are connected to the cross capacitor _Ccross902 . The cross regulation can be improved by the energy balance effect of the cross capacitor C _cross902 .

  The power supply circuit 900 can realize a three-output power supply circuit with outputs of 5V, 12V, and 24V.

[Tenth embodiment]
FIG. 17 is a diagram showing a power supply circuit 1000 according to the tenth embodiment of the present invention. The power supply circuit 1000 according to the tenth embodiment is mainly different from the power supply circuit 600 according to the sixth embodiment in that the numbers and positions of intermediate taps and cross capacitors are different.

The power supply circuit 1000 includes a primary winding Np, a first output winding (secondary winding) Ns1, a second output winding (secondary winding) Ns2, and a third output winding (two Secondary winding) Ns3, switch element Q1 connected in series with primary winding Np, control circuit Ic (not shown) for controlling switch element Q1, and power for supplying power to first output terminal Vo1 A rectifying element (diode) D1, a rectifying element (diode) D2 for supplying power to the second output terminal Vo2, and a rectifying element (diode) D3 for supplying power to the third output terminal Vo3 are provided. . The number of turns of the first output winding Ns1 and the second output winding Ns2 is the same, and the parts of the same polarity are connected via a cross capacitor _Ccross1001 , and the second output winding Ns2 The number of turns of the winding Ns3 is the same, and the intermediate tap Tap1001 is drawn out from the same polarity portion, and the corresponding intermediate tap Tap1001 and the third output winding Ns3 are connected via a capacitor.

The power supply circuit 1000 is the same as the operation principle of the power supply circuit 600. The winding Ns1 and Ns2 are connected to the cross capacitor C _cross1001 . The cross regulation can be improved by the energy balance effect of the cross capacitor C _cross1001 . Further, the winding Ns2-2 and the winding Ns3 are connected to the cross capacitor _Ccross1002 . The cross regulation can be improved by the energy balance action of the cross capacitor C _cross1002 .

  The power supply circuit 1000 can realize a three-output power supply circuit with outputs of 5 V, ± 12 V or 5 V, ± 15 V.

[Eleventh embodiment]
FIG. 18A is a diagram showing a power supply circuit 1100 according to the eleventh embodiment of the present invention. In the above-described embodiment, the cross capacitor connects the output winding constituting the transformer, but the cross capacitor may connect the output winding constituting the output mutual inductance.

The power supply circuit 1100 according to the eleventh embodiment has an output mutual inductance composed of the windings N1101 to N1104. Among them, the number of turns of the winding N1101 and the winding N1103 is the same. A cross capacitor C _cross1101 connects the extreme ends (node 1101 and node 1103) of the winding N1101 and the winding N1103. The other extremes (node 1102 and node 1104) are electrically connected via output capacitors C1 and C2.

Since the cross capacitor C _cross1101 , the output capacitors C1 and C2, the winding N1101 and the winding N1103 form a closed loop, the winding N1101 and the winding are _{operated by} the operation of the cross capacitor C _cross1101 as in the above embodiments. The voltage difference with N1103 can be reduced, and cross regulation between the two output terminals can be improved.

FIG. 18B is a diagram showing a power supply circuit 1101 which is a modification of the eleventh embodiment of the present invention. A power supply circuit having one plus (+) output end and one minus (-) output end is configured by connecting the other extremes (node 1102 and node 1104) via a capacitor C1. In addition, the winding N1101 and the winding Ns1102 having the same number of turns are closed via the capacitors C1 and _Ccross1101 , thereby reducing the voltage difference between the two output terminals and improving the cross regulation. Can do. In the present embodiment and the modification, the number of turns of the winding N1102 and the winding Ns1104 may be zero.

Np ... Primary winding; Ns1 ... First output winding; Ns2 ... Second output winding; Ns3 ... Third output winding; Q1 ... Switch element; Vo1 ... First output end; Vo2 ... Second output end; Vo3 ... 3rd output terminal; D1 ... Rectifier element; D2 ... Rectifier element; 100, 200, 201, 202, 300, 400, 500, 600, 700, 800, 900, 1000, 1100, 1101 ... Power supply circuit; Tap101, Tap201 , Tap202, Tap301, Tap401, Tap402, Tap601, Tap602, Tap701, Tap702, Tap801, Tap802, Tap803, Tap901, Tap902, Tap1001 ... medium tap; Node101 to 104, Node201 to 204, Node301 to 304, Node401 to 404, Node501~502, Node601~605, Node701~705, Node801~806, Node901~902 ... _{node; C cross, C cross501~502, C} cross601~602, C cross701~702, C cross801~803, C cross901~902, _C cross1001~1002, C cross1101 ... capacitor (cross capacitors); C1 to C3 ... capacitor (output capacitor); Lf1-1, Lf1-2, Lf1-3, Lf2, Lf3 ... leakage inductance; Ns1-1 Ns1-2, Ns1-3, Ns1-4, Ns2-1, Ns2-2, Ns2-3, Ns2-4, Ns3-1, Ns3-2 ... Winding; Ns2-add ... Additional winding, N1101-1104 ... Winding

Claims (9)

A power supply circuit having multiple output terminals,
Comprising a transformer having a plurality of output windings coupled to each other;
At least a pair of output windings among the plurality of output windings, and one end of the same poles of the part having both windings having the same number of turns is connected via a capacitor,
A power supply circuit, wherein the other end is electrically connected. The power supply circuit according to claim 1,
A power supply circuit characterized in that the other end of the portion of the at least one pair of output windings both having the same number of turns is directly connected. The power supply circuit according to claim 1 or 2,
A power supply circuit characterized in that at least one of the at least one pair of output windings is matched with the other output winding by adding an intermediate tap or an additional winding. The power supply circuit according to claim 1 or 2,
Comprising at least two output windings coupled to each other;
In each of the two output windings, the number of turns is the same, and an intermediate tap is drawn out from the same pole portion, and the two intermediate taps are connected via a capacitor. The power supply circuit according to claim 1 or 2,
A transformer having a first output winding, a second output winding, and a third output winding coupled to each other;
In the first output winding, the number of turns of either the second output winding or the third output winding is the same as that of the first output winding, and the first output tap is pulled out from the same polarity portion. The same polarity part of the wire is connected via a first capacitor, and the number of turns of the other output winding is the same as that of the other output winding. A power supply circuit, wherein the same polarity part of the wire is connected through a second capacitor. The power supply circuit according to claim 1 or 2,
A transformer having three output windings coupled to each other;
In each of the three output windings, the number of turns of each other is the same, and an intermediate tap is drawn from the same-polarity part, and any two of the three intermediate taps are connected via a capacitor. A featured power supply circuit. The power supply circuit according to claim 1 or 2,
A power supply circuit, wherein at least one of the plurality of output windings is feedback controlled. The power supply circuit according to claim 1 or 2,
A power supply circuit which is a flyback or forward power supply circuit. The power supply circuit according to claim 1 or 2,
The power supply circuit, wherein the plurality of output windings are output mutual inductances.

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