JP4442145B2 - Power supply - Google Patents

Description

  The present invention relates to a power supply device in which a plurality of resonant switching converters are connected in parallel.

  A parallel operation with a conventional current resonance type switching converter will be described. First, an example of a conventional current resonance type switching converter is shown in FIG. The drain of an N-type FET (Field Effect Transistor) 32 is connected to the positive side of the voltage source 31, its source is connected to the drain of the N-type FET 33, and its gate is connected to the control circuit 34.

  The source of the FET 33 is connected to the negative side of the voltage source 31, and its gate is connected to the control circuit 34. One of the primary winding sides of the converter transformer 36 is connected to the drain of the FET 33, and the other is connected to the source of the FET 33 via the resonance capacitor 35.

  One side of the secondary winding side of the converter transformer 36 is connected to the source of a P-type MOSFET (Metal Oxide Semiconductor Field Effect Transistor) 37, and the other side is connected to the source of a P-type MOSFET 38. The secondary winding of the converter transformer 36 is provided with a center tap, and the center tap is connected to the negative electrode side of the smoothing capacitor 41.

  The drain of the MOSFET 37 is connected to the positive electrode side of the smoothing capacitor 41 via the smoothing choke coil 40, and the gate thereof is connected to the control circuit 39. The drain of the MOSFET 38 is connected to the positive electrode side of the smoothing capacitor 41 via the smoothing choke coil 40, and the gate thereof is connected to the control circuit 39. A load 42 is provided in parallel with the smoothing capacitor 41. A control circuit 34 is connected to the positive electrode side of the smoothing capacitor 41.

  In the current resonance type switching converter of FIG. 5 having such a configuration, when obtaining a large power output, considering the temperature rise of the converter transformer, etc. Problems such as an increase in size and cost of the device itself arise.

  Therefore, there is a method of arranging current resonant switching converters in parallel in order to suppress an increase in size and cost and to obtain a large power output. As shown in FIG. 6, the primary winding side and secondary winding side of the current resonance type switching converter connected in parallel have the same components and the same configuration. Specifically, the FETs 32a and 32b and 33a and 33b on the primary winding side of the converter transformers 36a and 36b are the same parts and have the same switching cycle.

  Note that the primary windings of the transformers provided in each of the plurality of converter circuits are connected in parallel with each other so that the shared currents of the individual switching power supplies are equal, and further, the resonance windings included in the plurality of converter circuits are included. Some capacitors and each resonant inductor are connected to each other. By doing so, the impedance of the primary winding of the resonance circuit and the transformer is equal to each other in the plurality of converter circuits as seen from the switching element side, so that it is not necessary to select circuit elements constituting the resonance circuit. Thus, a reduction in productivity and an uneven load sharing due to circuit elements are avoided (see, for example, Patent Document 1).

JP-A-11-285249

  The resonance conditions of such a current resonance type switching converter are determined by a resonance converter transformer, a smoothing choke coil, and a capacitor. However, even if magnetic parts such as a resonant converter transformer and a smoothing choke coil are the same product, there are differences in the magnetic permeability, gap, etc. of the core, so that the inductances have different values. Therefore, in the configuration shown in FIG. 6, the difference in inductance of the smoothing choke coil causes the resonance condition to change.

  In the current resonance type switching converter provided in parallel as shown in FIG. 6, the difference in inductance between the smoothing choke coils 40a and 40b causes the resonance condition to change. This difference in resonance condition is a difference in current amplitude during parallel operation, and a large amount of current flows through a circuit provided with the smoothing choke coil 40a or 40b having a large inductance.

  As an example, when the inductance of the smoothing choke coil 40a is larger than the inductance of the smoothing choke coil 40b, the current I11a has a larger amplitude than the current I11b as shown in FIG. Further, the amplitude of the terminal voltage V11a of the resonance capacitor 35a is larger than that of the terminal voltage V11b of the resonance capacitor 35b.

  This non-uniform current balance increases the temperature of the FETs 32a, 33a, the converter transformer 36a, etc., destroys the balance of each component temperature, adversely affects the component life, and in the worst case leads to a problem of destruction. Further, there is a problem that power distribution output from the secondary winding side of the converter transformers 36a and 36b becomes uneven. These cause a decrease in product reliability.

  On the other hand, in order to make the current balance uniform, the inductances of magnetic components such as the converter transformers 36a and 36b and the resonance choke coils 40a and 40b are measured to create an optimum combination of values close to each other. There is a method of making the current balance almost equal and current balance. However, productivity may become extremely bad and it is not realistic.

  Accordingly, an object of the present invention is to provide a power supply apparatus that adjusts the balance of current even when two or more current resonance switching converters are operated in parallel, and equalizes the load of output power of each current resonance switching converter. There is to do.

In order to achieve the above-described problem, the invention of claim 1 is provided on the primary winding side of the transformer, and includes a drive circuit including first and second field effect transistors connected to the control circuit ,
A resonant circuit comprising a first choke coil and a capacitor inserted between the source and drain of the second field effect transistor and connected in series ;
A resonant converter block is composed of a smoothing circuit provided on the secondary winding side of the transformer,
The resonant converter block includes one end of the primary winding of the transformer and a connection point between the source of the first field effect transistor and the drain of the second field effect transistor, and the other end of the primary winding of the transformer; The first choke coil and the capacitor connection point are connected;
Providing at least two resonant converter blocks in parallel;
A resonant circuit is formed, and a first choke coil provided in parallel with the primary winding of the transformer is wound around the same core, and each is magnetically coupled,
The power supply apparatus is characterized in that the second choke coil constituting the smoothing circuit is wound around the same core and magnetically coupled to each other.

  Thus, even if the current resonance type switching converter is operated in parallel, it is wound around the same core on the primary winding side and / or the secondary winding side of the converter transformer, so that it is magnetically coupled. By providing the choke coil, the current flowing through each can be made equal.

  According to the present invention, even when two or more current resonance type switching converters are operated in parallel by a simple circuit configuration to obtain a large power output, the increase in size of the device can be suppressed and reduced. Cost can be reduced.

  According to the present invention, two or more current resonance types can be obtained by magnetically coupling choke coils provided on the primary winding side or secondary winding side of the converter transformer for resonance and correcting the inductance. The resonance condition during parallel operation of the switching converter can be set to an optimum value. Thus, since the resonance condition can be set to an optimum value, the phase difference and amplitude difference of the current can be removed, or the balance of the current can be made uniform.

  According to the present invention, the temperature balance of the parts used in the apparatus can be made uniform. Moreover, even if two or more current resonance type switching converters are operated in parallel, the burden of each output power can be made equal. Furthermore, the lifetime of the components at each location can be made uniform.

  Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 shows an overall configuration of a first embodiment to which the present invention is applied. The drain of the N-type FET 2 a is connected to the positive side of the voltage source 1, its source is connected to the drain of the N-type FET 3 a, and its gate is connected to the control circuit 4.

  The source of the FET 3 a is connected to the negative side of the voltage source 1, and its gate is connected to the control circuit 4. One side of the primary winding side of the converter transformer 6a is connected to the drain of the FET 3a, and the other side is connected to the source of the FET 3a via the resonance capacitor 5a.

  One side of the secondary winding side of converter transformer 6a is connected to the source of P-type MOSFET 7a, and the other is connected to the source of P-type MOSFET 8a. The secondary winding of the converter transformer 6 a is provided with a center tap, and the center tap is connected to the negative electrode side of the smoothing capacitor 11.

  The drain of the MOSFET 7 a is connected to the positive electrode side of the smoothing capacitor 11 via the smoothing choke coil 10 a, and the gate thereof is connected to the control circuit 9. The drain of the MOSFET 8 a is connected to the positive side of the smoothing capacitor 11 through the smoothing choke coil 10 a, and the gate thereof is connected to the control circuit 9. A load 12 is provided in parallel with the smoothing capacitor 11. A control circuit 4 is connected to the positive electrode side of the smoothing capacitor 11.

  The drain of the N-type FET 2 b is connected to the positive side of the voltage source 1, its source is connected to the drain of the N-type FET 3 b, and its gate is connected to the control circuit 4. The source of the FET 3 b is connected to the negative side of the voltage source 1, and its gate is connected to the control circuit 4. One side of the primary winding side of the converter transformer 6b is connected to the drain of the FET 3b, and the other side is connected to the source of the FET 3b via the resonance capacitor 5b.

  One side of the secondary winding side of converter transformer 6b is connected to the source of P-type MOSFET 7b, and the other is connected to the source of P-type MOSFET 8b. The secondary winding of the converter transformer 6 b is provided with a center tap, and the center tap is connected to the negative electrode side of the smoothing capacitor 11.

  The drain of the MOSFET 7b is connected to the positive electrode side of the smoothing capacitor 11 through the smoothing choke coil 10b, and the gate thereof is connected to the control circuit 9. Since the smoothing choke coils 10a and 10b are wound around the same core, they are magnetically coupled. The drain of the MOSFET 8b is connected to the positive electrode side of the smoothing capacitor 11 via the smoothing choke coil 10b, and the gate thereof is connected to the control circuit 9.

  In the first embodiment, the FETs 2a, 2b, 3a, and 3b are the same component, the FETs 2a and 2b have the same switching cycle, and the FETs 3a and 3b have the same switching cycle. The primary winding side and the secondary winding side of the current resonance type switching converter connected in parallel have the same configuration with the same components.

  Note that currents I1a and I1b from voltage source 1 flowing to the primary winding side of converter transformers 6a and 6b when FETs 2a and 2b are on, and primary windings of converter transformers 6a and 6b when FETs 3a and 3b are on. Discharge currents I2a and I2b from resonance capacitors 5a and 5b flowing to the side are referred to as resonance currents.

  The operation of the first embodiment will be described. When FETs 2a and 2b are turned on and FETs 3a and 3b are turned off, currents I1a and I1b flow from voltage source 1 to the primary windings of converter transformers 6a and 6b, and charges are accumulated in resonance capacitors 5a and 5b.

  On the secondary winding side of converter transformers 6a and 6b, MOSFETs 8a and 8b are simultaneously turned on for synchronous rectification, and currents I4a and I4b flow. At this time, the MOSFETs 7a and 7b are turned off. The currents I4a and I4b are combined via the smoothing choke coils 10a and 10b, respectively, and flow to the load 12 as the current I5. At this time, since the smoothing choke coils 10a and 10b use the same core, the inductance is corrected and the resonance conditions are substantially equal. Therefore, the currents I1a and I1b are also substantially equal as shown in FIG. Similarly, the terminal voltages V1a and V1b of the resonance capacitors 5a and 5b are substantially equal.

  When the FETs 2a and 2b are turned off, the current supplied from the voltage source 1 is cut off, so that the currents I1a and I1b do not flow. When the FETs 3a and 3b are turned on, currents I2a and I2b having opposite directions to the currents I1a and I1b flow. The currents I2a and I2b are output from the resonance capacitors 5a and 5b.

  On the secondary winding side of converter transformers 6a and 6b, MOSFETs 7a and 7b are simultaneously turned on for synchronous rectification, and currents I3a and I3b flow. At this time, the MOSFETs 8a and 8b are turned off. The currents I3a and I3b are combined via the smoothing choke coils 10a and 10b, respectively, and flow to the load 12 as the current I5. At this time, since the smoothing choke coils 10a and 10b use the same core, the inductance is corrected and the resonance conditions are substantially equal. Therefore, the currents I1a and I1b are also substantially equal as shown in FIG. Similarly, the terminal voltages V1a and V1b of the resonance capacitors 5a and 5b are substantially equal.

  Thus, even if the circuit configuration is such that each current resonance type switching converter operates in parallel to obtain one output, the power burden can be made equal.

  A second embodiment of the present invention will be described with reference to FIG. In the second embodiment, a resonance choke coil 21a is provided in parallel with the primary winding side of the converter transformer 6a, and similarly, a resonance choke coil 21b is provided in parallel with the primary winding side of the converter transformer 6b. Yes. Since the resonance choke coils 21a and 21b are wound around the same core, they are magnetically coupled. Therefore, the currents I1a and I1b and the voltages V1a and V1b are substantially equal.

  The smoothing choke coil 22 a is provided between the connection point between the drain of the MOSFET 7 a and the drain of the MOSFET 8 a and the positive electrode side of the smoothing capacitor 11. The smoothing choke coil 22 b is provided on the connection point between the drain of the MOSFET 7 b and the drain of the MOSFET 8 b and on the positive electrode side of the smoothing capacitor 11.

  A third embodiment of the present invention will be described with reference to FIG. In the third embodiment, resonance choke coils 21a and 21b that are magnetically coupled because they are wound around the same core are provided in parallel with the primary windings of the converter transformers 6a and 6b, respectively. Yes.

  Further, a smoothing choke coil 10 a is provided between a connection point between the drain of the MOSFET 7 a and the drain of the MOSFET 8 a and the positive electrode side of the smoothing capacitor 11. Similarly, a smoothing choke coil 10 b is provided between a connection point between the drain of the MOSFET 7 b and the drain of the MOSFET 8 b and the positive electrode side of the smoothing capacitor 11. Since the smoothing choke coils 10a and 10b are wound around the same core as described above, they are magnetically coupled.

  Note that parasitic diodes are added to the MOSFETs 7a, 7b, 8a, and 8b described above.

  The present invention is not limited to the above-described embodiment of the present invention, and various modifications and applications are possible without departing from the spirit of the present invention.

It is a circuit diagram for demonstrating 1st Embodiment to which this invention is applied. It is a characteristic view for demonstrating 1st Embodiment to which this invention is applied. It is a circuit diagram for demonstrating 2nd Embodiment to which this invention is applied. It is a circuit diagram for demonstrating 3rd Embodiment to which this invention is applied. It is a circuit diagram for demonstrating a current resonance type switching converter. It is the schematic for demonstrating the parallel operation | movement of a current resonance type switching converter. It is a characteristic view for demonstrating the parallel operation | movement of a current resonance type switching converter.

Explanation of symbols

1 Voltage source 2a, 2b, 3a, 3b FET
4, 9 Control circuit 5a, 5b Resonance capacitor 6a, 6b Converter transformer 7a, 7b, 8a, 8b MOSFET
10a, 10b Smoothing choke coil 11 Smoothing capacitor 12 Load

Claims (1)

A drive circuit comprising first and second field effect transistors provided on the primary winding side of the transformer and connected to the control circuit ;
A resonant circuit comprising a first choke coil and a capacitor inserted between the source and drain of the second field effect transistor and connected in series ;
A resonant converter block is configured from a smoothing circuit provided on the secondary winding side of the transformer,
In the resonant converter block, one end of the primary winding of the transformer is connected to a connection point between the source of the first field effect transistor and the drain of the second field effect transistor, and the primary winding of the transformer Are connected to the connection point of the first choke coil and the capacitor,
Providing at least two resonant converter blocks in parallel;
Configuring the resonant circuit, winding the first choke coil provided in parallel with the primary winding of the transformer around the same core, and magnetically coupling them, respectively;
A power supply apparatus, wherein the second choke coil constituting the smoothing circuit is wound around the same core and magnetically coupled to each other.

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