JP5013848B2 - Switching power supply - Google Patents

Description

  The present invention relates to a switching power supply device that achieves high efficiency, miniaturization, and cost reduction.

In our company, as shown in FIG. 9, a bridge circuit having four switch elements Q1 to Q4 is connected to a DC power source V1, and an output transformer T1 that insulates the primary and secondary terminals at the output terminal of the bridge circuit. The primary winding N11 is connected. The secondary winding of the output transformer T1 has applied for a patent for a switching power supply that supplies power to a load via an output circuit having two switch elements Q5 and Q6 (see Patent Document 1).
JP 2003-189622 A

  The output transformer T1 according to the switching power supply device shown in FIG. 9 includes two cores 10 and 20. Each of the cores 10 and 20 is provided with four magnetic legs 11 to 14 and 21 to 24 in parallel. The magnetic legs 12, 13, 22, and 23 in the center of the cores 10 and 20 are shorter than the magnetic legs 11, 14, 21, and 24 at both ends, and when the two cores 10 and 20 are brought into contact with each other, The magnetic legs 12, 13, 22, 23 are configured to have a gap. Of the two cores 10 and 20, the primary winding N <b> 11 is wound across the magnetic legs of the center two 12 and 13 of one core 10. The first secondary winding N 21 is wound around one magnetic leg 22 in the center of the other core 20, and the second secondary winding N 22 is wound around the other magnetic leg 23 in the center of the other core 20. A first rectifying switch element Q5 is connected to the first secondary winding N21, and a second rectifying switch element Q6 is connected to the second secondary winding N22.

  However, in the control method in this switching power supply apparatus, as shown in FIG. 10, the rest periods t1 and t2 of the primary side switch elements Q1 to Q4 are in a high impedance state and the primary side switch elements Q1 to Q4 are in that period. The voltage of becomes very unstable. Also, when the potential is biased to high or low due to sudden fluctuations in input / output and other abnormal operation characters, magnetic flux unbalance occurs in the output transformer, and the magnetic flux concentrates on one half of the core, causing the worst switching elements Q1 to Q4. There is a risk of destroying. In particular, when the transformer and choke are integrated and the secondary winding is wound on separate magnetic legs, there is also a problem that symmetry is easily lost.

  The present invention has been made in view of the above problems, and provides a switching power supply device in which the voltage during the idle period of the primary side switching element is stable and magnetic flux unbalance is unlikely to occur even during an abnormal operation.

In order to solve the above-mentioned problems, a switching power supply device of the present invention connects a full-bridge type bridge circuit to a DC power supply, and a primary winding of an output transformer that insulates between a primary and a secondary at an output terminal of the bridge circuit And a power supply for supplying power to the load through the output transformer, the output transformer having at least two cores, each of which has three or four magnetic legs in parallel. The magnetic leg at the center of the core is shorter than the magnetic legs at both ends, and when the two cores are brought into contact with each other, a gap is formed in the magnetic leg at the center of the core having the magnetic legs. The primary winding and the two secondary windings are wound around one magnetic leg or two magnetic legs, respectively, and the phase shift control is performed on the switch elements constituting the bridge circuit. It characterized that you have urchin configuration.
A capacitor is connected between one end of the output terminal of the bridge circuit and the primary winding, or in the primary winding.

  The output transformer includes two cores, and each of the cores has four magnetic legs arranged in parallel. The two magnetic legs at the center of the core are shorter than the magnetic legs at both ends, and the two cores at both ends of the two cores. When the magnetic legs are brought into contact with each other, a gap is formed between the two magnetic legs in the center.

Further, of the two cores, the primary winding is wound over the two central magnetic legs of one core, and the first secondary winding is wound around the central magnetic leg of the other core, A second secondary winding is wound around the other magnetic leg in the center of the other core.
Alternatively, of the two cores, a primary winding is wound around each of the magnetic legs in the center of one of the cores, and the first secondary winding is connected to one of the magnetic legs in the center of the other core. A wire is wound and a second secondary winding is wound around the other magnetic leg in the center of the other core.

The output transformer has two cores, and one core is composed of only one magnetic leg, while the other core is provided with three magnetic legs in parallel. The magnetic leg at the center is shorter than the magnetic legs at both ends, and when the magnetic legs at both ends of the other core are brought into contact with one core, a gap is formed between the magnetic leg at the center of the other core and one core. It is configured as described above.
Further, the primary winding is wound around the magnetic leg in the center of the other core, and the first secondary winding and the second secondary winding are wound around both ends of the other core, respectively. To do.

The output transformer has three cores, the first core is composed of only one magnetic leg, while the second and third cores are provided with three magnetic legs in parallel. The magnetic legs at the center of the second and third cores are shorter than the magnetic legs at both ends, and the second and third cores when the magnetic legs at both ends of the second and third cores are brought into contact with the first core. A gap is formed between the magnetic leg in the center of the core and the first core.
In addition, a primary winding is wound around and connected to the magnetic legs at the center of the second and third cores, respectively, and the first secondary winding and the first are connected to the magnetic legs at the center of the second and third cores, respectively. Two secondary windings are wound around.
Or, two primary windings are wound around and connected to the first core, and the first secondary winding and the second secondary winding are wound around the first core, respectively. And

  According to the present invention, by performing phase shift control, the idle period of the primary-side switch element is in a low impedance state, and the voltage during the idle period of the primary-side switch element is very stable. For this reason, magnetic flux unbalance is unlikely to occur even during an abnormal operation, and the symmetry of the operation is maintained even if the secondary winding is wound around separate magnetic legs in an integrated transformer and choke type. Further, it is possible to prevent partial excitation by connecting a capacitor between one end of the output terminal of the bridge circuit and the primary winding or in the primary winding.

  FIG. 1 shows the best mode for carrying out the present invention. In the switching power supply according to the present embodiment, a full-bridge type bridge circuit having four switch elements Q1 to Q4 is connected to a DC power supply V1, and a capacitor C1 for preventing bias excitation is provided at one end of the output terminal of the bridge circuit. A full-bridge type switching circuit is configured by connecting this capacitor C1 and the other end of the output terminal of the bridge circuit to the primary winding N11 of the output transformer T1 that insulates the primary and secondary. .

  The output transformer T1 constituting the switching power supply device according to this embodiment includes two cores 10 and 20. Each of the cores 10 and 20 is provided with four magnetic legs 11 to 14 and 21 to 24 in parallel. The two magnetic legs 12, 13, 22, 23 at the center are configured shorter than the two magnetic legs 11, 14, 21, 24 at both ends. When the magnetic legs at both ends of the two cores 10 and 20 are brought into contact with each other, a gap is formed between the two magnetic legs 12, 22, 13, and 23 in the center. The primary winding N11 is wound across the two magnetic legs 12 and 13 in the center of one core 10, the first secondary winding N21 is wound around one magnetic leg 22 in the center of the other core 20, and the other A second secondary winding N22 is wound around the other magnetic leg 23 in the center of the core 20 of the core. From the above configuration, in particular, when the magnetic legs at both ends of the two cores 10 and 20 are brought into contact with each other, a gap is formed between the two magnetic legs 12, 22, 13, and 23 in the center. As a result, the output transformer T1 according to this embodiment is an integrated transformer and choke as shown in the equivalent circuit of FIG.

  The two secondary windings N21 and N22 are connected to the switch elements Q5 and Q6, respectively, and connected to the load together with the smoothing capacitor C2 to form an output circuit so that power is supplied from the power source to the load via the output transformer T1. It is configured.

  A control circuit (not shown) is connected to the control terminals of the switch elements Q1 to Q4 constituting the full bridge type switching circuit, and the phase shift control is performed using this control circuit. Specifically, the control is performed as follows.

  The phases of the high-order switch element Q1 of one arm and the high-order switch element Q3 of the other arm of the four switch elements Q1 to Q4 constituting the full-bridge type switching circuit are controlled according to the output voltage. The period when the high-order switch element Q1 of one arm and the low-order switch element Q4 of the other arm are simultaneously turned on, and the low-order switch element Q2 of one arm and the high-order switch element Q3 of the other arm simultaneously The period during which the transistor is turned on is adjusted according to the output voltage. Here, the power transmitted from the switching circuit to the output circuit is the period during which the high-order side switch element Q1 of one arm and the low-order side switch element Q4 of the other arm are simultaneously turned on, and the low order side of one arm. Since the switching element Q2 and the higher-order switching element Q3 of the other arm are simultaneously determined to be in the ON state, the output voltage can be stabilized to a desired value by controlling the phase.

  The switching power supply device configured as described above operates as follows. The circuit operation is shown in FIG. 3 and will be described with reference to FIG. First, before the time t1 shown in FIG. 3 is reached, the lower switch element Q4 of the other arm is turned on. Thereafter, the high-order side switch element Q1 of one arm is turned on. As a result, the current flowing from the DC power source V1 flows through the high-side switch element Q1 of one arm, the capacitor C1, the primary winding N11, and the low-side switch element Q4 of the other arm, and also flows through the output transformer T1. Power is supplied to the load via the first rectifying switch element Q5 via the first secondary winding N21.

  Subsequently, at time t1, the high-order switch element Q1 of one arm is turned off, and at the same time, the low-order switch element Q2 of one arm is turned on. As a result, a current flows from the lower switch element Q4 of the other arm to the capacitor C1 and the primary winding N11 via the lower switch element Q2 of the one arm. At the same time, electric power is supplied to the load via the first rectifying switch element Q5 via the first secondary winding N21 of the output transformer T1.

  Subsequently, between the time t1 and the time t2 shown in FIG. 3, the lower switch element Q2 of one arm is in the ON state, and the lower switch Q4 of the other arm is turned OFF and at the same time the high switch of the other arm is turned off. Element Q3 is turned on. As a result, the current flowing from the DC power source V1 flows through the high-side switch element Q3 of the other arm, the primary winding N11, the capacitor C1, the low-side switch element Q2 of one arm, and the output transformer T1. Power is supplied to the load via the first rectifying switch element Q6 via the first secondary winding N22.

  Subsequently, at time t2, the high-order switch element Q3 of the other arm is turned off, and at the same time, the low-order switch element Q4 of the other arm is turned on. As a result, a current flows from the lower switch element Q2 of one arm to the primary winding N11 and the capacitor C1 via the lower switch element Q4 of the other arm. At the same time, power is supplied to the load via the first secondary winding N22 of the output transformer T1 via the first rectifying switch element Q6.

  The switching power supply according to the present embodiment is in a low-impedance state during the idle period of the primary-side switch element due to the operation described above, and the voltage during the idle period of the primary-side switch element is very stable. For this reason, magnetic flux unbalance is unlikely to occur even during an abnormal operation, and the symmetry of the operation is maintained even if the secondary winding is wound around separate magnetic legs in an integrated transformer and choke type. Further, by connecting a capacitor between one end of the output terminal of the bridge circuit and the primary winding or in the primary winding, partial excitation can be prevented and the above-described operation can be maintained.

  Subsequently, a second embodiment shown in FIG. 4 will be described. The basic circuit configuration of this embodiment is almost the same as that of the above embodiment. However, in the first embodiment shown in FIG. 1, the capacitor C1 for preventing partial excitation is connected between the full-bridge type bridge circuit and the primary winding N11 of the output transformer T1, whereas FIG. 4 differs from the second embodiment in that a capacitor C1 for preventing partial excitation is connected in the primary winding N11. The operation of this embodiment is omitted since it is almost the same as that of the above embodiment.

  FIG. 5 shows a third embodiment. Also in this embodiment, the configurations of the cores 10 and 20 are substantially the same as those in the above embodiment. However, the winding method of the primary winding is different from the above embodiment as follows. The primary winding is wound around the center of one of the cores as in the above embodiment. On the other hand, in the present embodiment, one end of the first primary winding N11 wound around the magnetic flux 12 at the center is connected to the output terminal provided on one arm. One end of the second primary winding N12 wound around the other magnetic flux 13 at the center is connected to an output terminal provided on the other arm. The other ends of the two primary windings N11 and N12 are connected via a capacitor C1 for preventing bias excitation. Since the operation is almost the same as that of the above embodiment, it is omitted.

  FIG. 6 shows a fourth embodiment. The output transformer T1 according to this embodiment includes two cores 30 and 40, and one core 30 is provided with three magnetic legs 31, 32, and 33 in parallel, while the other core 40 has one core. It consists only of magnetic legs of books. The magnetic leg 32 at the center of one core 30 is shorter than the magnetic legs at both ends, and when the magnetic legs at both ends of the one core 30 are brought into contact with the other core 40, A gap is formed between the other core 40.

  Next, how to wind the winding around the output transformer T1 according to this embodiment will be described. In this embodiment, the primary winding N <b> 11 is wound around the magnetic leg 32 at the center of the core 30. One end of the primary winding N11 is connected to the output terminal of one arm via a capacitor C1 for preventing bias excitation, and the other end of the primary winding N11 is connected to the output terminal of the other arm. A first secondary winding N21 is wound around a magnetic leg 31 at one end of one core 30, and a second secondary winding N22 is wound around a magnetic leg 33 at the other end of the core 30. Since the operation is almost the same as that of the above embodiment, it is omitted.

  FIG. 7 shows a fifth embodiment. The output transformer T1 according to this embodiment includes three cores 30, 40, 50, and the first and third cores 30, 50 are provided with three magnetic legs 31-33, 51-53 in parallel. On the other hand, the second core 40 is composed of only one magnetic leg. The magnetic legs 32 and 52 at the center of the first and third cores 30 and 50 are shorter than the magnetic legs at both ends, and the magnetic legs at both ends of the first and third cores 30 and 50 abut against the second core 40. In this case, a gap is formed between the magnetic legs 32 and 52 at the center of the first and third cores 30 and 50 and the second core 40.

  Next, how to wind the winding around the output transformer T1 according to this embodiment will be described. In this embodiment, the first primary winding N11 is wound around the center magnetic leg 32 of the first core 30, and the second primary winding N12 is wound around the center magnetic leg 52 of the third core 50. ing. One end of a first primary winding N11 wound around a magnetic leg 32 at the center of the first core 30 is connected to an output terminal provided on one arm. One end of the second primary winding N12 wound around the magnetic leg 52 at the center of the third core 50 is connected to the output terminal provided on the other arm. The other ends of the two primary windings N11 and N12 are connected via a capacitor C1 for preventing bias excitation. A first secondary winding N21 is wound around the magnetic leg 52 at the center of the third core 50, and a second secondary winding N22 is wound around the magnetic leg 32 at the center of the first core 30. Since the operation is almost the same as that of the above embodiment, it is omitted.

  FIG. 8 shows a sixth embodiment. The output transformer T1 according to this embodiment includes three cores 30, 40, 50, and the first and third cores 30, 50 are provided with three magnetic legs 31-33, 51-53 in parallel. On the other hand, the second core 40 is composed of only one magnetic leg. The magnetic legs 32 and 52 at the center of the first and third cores 30 and 50 are shorter than the magnetic legs at both ends, and the magnetic legs at both ends of the first and third cores 30 and 50 abut against the second core 40. In this case, a gap is formed between the magnetic legs 32 and 52 at the center of the first and third cores 30 and 50 and the second core 40.

  Next, how to wind the winding around the output transformer T1 according to this embodiment will be described. In this embodiment, the first primary winding N11 is wound around the second core 40, and the second primary winding N12 is wound around the second core 40. One end of the first primary winding N11 wound around the second core 40 is connected to an output terminal provided on one arm. One end of the second primary winding N12 wound around the second core 40 is connected to the output terminal provided on the other arm. The other ends of the two primary windings N11 and N12 are connected via a capacitor C1 for preventing bias excitation. The first secondary winding N21 is wound around the second core 40, and the second secondary winding N22 is wound around the second core 40. Since the operation is almost the same as that of the above embodiment, it is omitted.

  The first to sixth embodiments are merely examples of the present invention. In the present invention, an output transformer having at least two cores is provided, and at least one core is provided with three or four magnetic legs in parallel, respectively. Short and constructed so that there is a gap in the center magnetic leg of the core having the magnetic legs when the two cores are brought into contact, and straddles one magnetic leg or two magnetic legs. The present invention is not limited to the above-described embodiment as long as the primary winding and the two secondary windings are wound, and the switch elements constituting the bridge circuit are configured to perform phase shift control.

  According to the present invention, by performing phase shift control, the idle period of the primary-side switch element is in a low impedance state, and the voltage during the idle period of the primary-side switch element is very stable. For this reason, magnetic flux unbalance is unlikely to occur even during an abnormal operation, and the symmetry of the operation is maintained even if the secondary winding is wound around separate magnetic legs in an integrated transformer and choke type. Further, by connecting a capacitor between one end of the output terminal of the bridge circuit and the primary winding or in the primary winding, it is possible to prevent partial excitation, which is industrially applicable.

It is a circuit block diagram of the best embodiment of the switching power supply device according to the present invention. FIG. 2 is an equivalent circuit diagram of the embodiment shown in FIG. 1. 1 is an operation waveform diagram in the embodiment shown in FIG. FIG. 3 is a circuit configuration diagram of a second embodiment different from the embodiment shown in FIG. 1. It is a circuit block diagram of 3rd Example different from the said Example. It is a circuit block diagram of 4th Example different from the said Example. It is a circuit block diagram of 5th Example different from the said Example. It is a circuit block diagram of 6th Example different from the said Example. It is a circuit block diagram of the conventional switching power supply device. FIG. 10 is an operation waveform diagram in the conventional example shown in FIG. 9.

Explanation of symbols

V1 DC power supply T1 Output transformers Q1 to Q6 Switch elements 10, 20, 30, 40, 50 Cores 11 to 14, 21 to 24, 31 to 33, 51 to 53 Magnetic leg C1 Capacitor C2 for preventing bias excitation Smoothing capacitor N11, N12 Primary winding N21, N22 Secondary winding

Claims (5)

Connect a full-bridge type bridge circuit to the DC power supply, connect the primary winding of the output transformer that insulates between the primary and secondary to the output terminal of this bridge circuit, and supply power to the load through this output transformer A switching power supply device,
The output transformer includes two cores, and each of the cores has four magnetic legs arranged in parallel. The two magnetic legs at the center of the core are shorter than the magnetic legs at both ends, and the two cores at both ends of the two cores. When the magnetic legs are brought into contact with each other, a gap is formed between the two magnetic legs in the center. Of the two cores, the primary winding straddles the two magnetic legs in the center of one of the cores. A wire is wound, a first secondary winding is wound around one magnetic leg in the center of the other core, and a second secondary winding is wound around the other magnetic leg in the center of the other core . A switching power supply device configured to control phase shift of switch elements constituting the bridge circuit. Connect a full-bridge type bridge circuit to the DC power supply, connect the primary winding of the output transformer that insulates between the primary and secondary to the output terminal of this bridge circuit, and supply power to the load through this output transformer A switching power supply device,
The output transformer includes two cores, and each of the cores has four magnetic legs arranged in parallel. The two magnetic legs at the center of the core are shorter than the magnetic legs at both ends, and the two cores at both ends of the two cores. When the magnetic legs are brought into contact with each other, a gap is formed between the two magnetic legs in the center, and a primary winding is wound around each magnetic leg in the center of one of the two cores. The first secondary winding is wound around one magnetic leg in the center of the other core, and the second secondary winding is wound around the other magnetic leg in the center of the other core. A switching power supply device that is rotated and configured to control phase shift of a switch element that constitutes the bridge circuit. Connect a full-bridge type bridge circuit to the DC power supply, connect the primary winding of the output transformer that insulates between the primary and secondary to the output terminal of this bridge circuit, and supply power to the load through this output transformer A switching power supply device,
The output transformer has three cores, the first core is composed of only one magnetic leg, while the second and third cores are provided with three magnetic legs in parallel. The magnetic legs at the center of the second and third cores are shorter than the magnetic legs at both ends, and the second and third cores when the magnetic legs at both ends of the second and third cores are brought into contact with the first core. A gap is formed between the center magnetic leg of the first core and the first core, and a primary winding is wound around and connected to the center magnetic legs of the second and third cores. The first secondary winding and the second secondary winding are wound around the center magnetic legs of the second and third cores, respectively, and the phase shift control is performed on the switch elements constituting the bridge circuit. A switching power supply device characterized in that the switching power supply device is configured as described above. Connect a full-bridge type bridge circuit to the DC power supply, connect the primary winding of the output transformer that insulates between the primary and secondary to the output terminal of this bridge circuit, and supply power to the load through this output transformer A switching power supply device,
The output transformer has three cores, the first core is composed of only one magnetic leg, while the second and third cores are provided with three magnetic legs in parallel. The magnetic legs at the center of the second and third cores are shorter than the magnetic legs at both ends, and the second and third cores when the magnetic legs at both ends of the second and third cores are brought into contact with the first core. A gap is formed between the magnetic leg in the center of the core and the first core, and two primary windings are wound around the first core and connected to the first core. A switching power supply device in which a first secondary winding and a second secondary winding are wound respectively, and the switch elements constituting the bridge circuit are configured to perform phase shift control. . 5. The switching power supply device according to claim 1, wherein a capacitor is connected between one end of the output terminal of the bridge circuit and the primary winding, or in the primary winding. 6.

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