JP2009118648A - Switching power supply - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a switching power supply that miniaturizes parts and also achieves a ZVS. <P>SOLUTION: In the switching power supply, a section between the primary side and the secondary side is insulated by a transformer T, two first series circuits 11 and 12 with an even number of switching elements Q1, Q2, Q3 and Q4 connected in series with the primary side are provided and the middle point of the series circuits is connected to a primary winding for the transformer. In the switching power supply, second series circuits with two switching elements Q11, Q12, Q13 and Q14 connected in series are connected in parallel with the first series circuits, and resonance chokes L11 and L12 are connected between the middle point of the first series circuits and the middle point of the second series circuits. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a switching power supply apparatus in which a primary and a secondary are insulated by a transformer and a switching element is provided on the primary side.

A conventional full bridge converter is shown in FIG. In this full bridge converter, a primary circuit and a secondary circuit are insulated by a transformer T, and two switch elements Q1, Q2, Q3, and Q4 are connected in series on the primary side to form a series circuit (hereinafter referred to as “arm”) 11,. 12 are provided, and these arms 11 and 12 are connected in parallel to form a bridge circuit, and the midpoint of each of the series circuits 11 and 12 is connected to the primary winding of the transformer T. A resonance choke L2 is connected between one end of the primary winding and the midpoint of the arm 12, and phase shift control is performed (see, for example, Patent Document 1).
U.S. Pat. No. 4,864,479

  Since this full bridge converter can excite the transformer T on both the positive and negative sides, there is an advantage that the transformer can be made smaller than a converter that oscillates with one switch element on one side such as a forward converter. In addition, since the frequency of the voltage waveform applied to the filter (hereinafter referred to as “LC filter”) including the output choke L1 and the smoothing capacitor C2 is twice that of the forward converter, there is an advantage that the LC filter can be downsized. Further, the full bridge converter has an advantage that zero volt switching (hereinafter referred to as “ZVS”) can be realized without adding an auxiliary switch when phase shift control is performed.

  However, as shown in FIG. 9, the full-bridge type switching power supply device that performs phase shift control has a problem that the conduction loss is larger than the PWM control shown in FIG. 10 because the circulating current flows to the primary side circuit. For this reason, a loss is large and parts cannot be reduced in size. Since this requires a power outage retention time, it becomes more prominent with a power supply that is designed to have a narrow duty at normal times. Further, since ZVS is realized by using the energy of the circulating current, there is a problem that ZVS cannot be performed when the load is lightened.

  The present invention has been made in view of the above problems, and provides a switching power supply device that realizes ZVS while miniaturizing components.

In order to solve the above-described problems, a switching power supply according to the present invention includes one or a plurality of first series circuits having an even number of switching elements in which primary and secondary are insulated by a transformer and connected in series on the primary side. A switching power supply device in which a midpoint of the series circuit is connected to a primary winding of the transformer, and a second series circuit having an even number of switch elements connected in series in parallel with the first series circuit And a resonance choke is connected between the midpoint of the first series circuit and the midpoint of the second series circuit.
The first series circuit is provided in two, and the second series circuit is connected in parallel with the first series circuit.
Or it has one said 1st series circuit, The 3rd series circuit formed by connecting a some capacitor | condenser in series with said 1st series circuit is connected, It is characterized by the above-mentioned.

Further, the switching power supply according to the present invention is a switching power supply in which the primary and secondary are insulated by a transformer, and the switching element is connected in series to the primary winding of the transformer. A first series circuit having the first series circuit, a second series circuit having a rectifier element and a switch element connected in parallel with the first series circuit, and a primary winding and a switch element constituting the first series circuit And a resonance choke is connected between a connection point between the rectifying element and the switch element constituting the second series circuit.
Further, the first series circuit has two, the primary windings of the transformer constituting the first series circuit are connected to each other, and the second series circuit is connected in parallel with the first series circuit. Are connected.

  According to the present invention, each of the second series circuits is connected in parallel with the first series circuit, and each resonance choke is provided between the midpoint of the first series circuit and the midpoint of the second series circuit. By being connected, the current of the resonant choke is greatly reduced, so that loss can be reduced and the resonant choke can be downsized.

  Further, according to the above configuration, ZVS can be realized without using phase shift control, so that it is not necessary to flow a circulating current, and the loss of the primary winding of the switch and the transformer can be reduced. Furthermore, since ZVS is not performed by the energy of the circulating current, the ZVS condition is not influenced by the load, and ZVS can be stably realized at full load or no load, and low noise is achieved even at no load.

  In addition, since only the current for discharging the parasitic capacitance of the main circuit flows in the second series circuit, the switch of the second series circuit may be small.

  A circuit diagram of the best mode for carrying out the invention is shown in FIG. The switching power supply shown in FIG. 1 is an embodiment of a full bridge type switching power supply. This switching power supply device is a first series circuit (hereinafter referred to as “first arm”) in which primary and secondary are insulated by a transformer T and two switch elements Q1, Q2 and Q3, Q4 are connected in series on the primary side. .) 11 and 12 are provided, and these arms 11 and 12 are connected in parallel to form a bridge circuit, and the midpoint of each of the series circuits 11 and 12 is connected to the primary winding of the transformer T.

  The secondary side includes a rectifier circuit including two rectifier elements D1 and D2, and a smoothing circuit including an output choke L1 and a smoothing capacitor C2, and the secondary winding of the transformer T is connected to the rectifier circuit. Is connected to a smoothing circuit to supply an output voltage. In the present invention, the configuration on the secondary side is not limited.

  Subsequently, the present embodiment is characterized by the following configuration. Two second series circuits (hereinafter referred to as “second arms”) 21 and 22 in which two switch elements Q11 and Q12 and Q13 and Q14 are connected in series are provided, and these second arms 21 and 22 are connected in parallel. It is. The second arms 21 and 22 are connected in parallel to the two first arms 11 and 12. A resonance choke L11 is connected between the midpoint of one first arm 11 and the midpoint of one second arm 21, and the midpoint of the other first arm 12 and the other second arm 21 are connected. Another resonance choke L12 is connected between the middle point of the arm 22 and the other arm 22.

  The switching power supply device configured as described above operates as follows. Immediately before the high-side switches Q1 and Q3 provided on the first arms 11 and 12 are turned on, the high-side switches Q11 and Q13 provided on the second arms 21 and 22 are turned on to discharge the parasitic capacitance. The discharged energy moves to the resonance chokes L11 and L12, and the high side switch Q1 provided on the first arms 11 and 12 at the timing when the high side switches Q11 and Q13 provided on the second arms 21 and 22 are turned off. , Q3 and the body diodes of the low-side switches Q12, Q14 provided on the second arms 21, 22 are regenerated to the input capacitor C1. Thereby, zero voltage switching of the high side switches Q1 and Q3 becomes possible, and switching loss can be suppressed.

  Also, immediately before the low-side switches Q2 and Q4 provided on the first arms 11 and 12 are turned on, the low-side switches Q12 and Q14 provided on the second arms 21 and 22 are turned on to discharge the parasitic capacitance. The discharged energy moves to the resonance chokes L11 and L12, and at the timing when the low side switches Q12 and Q14 provided on the second arms 21 and 22 are turned off, the low side switches Q2 and Q2 provided on the first arms 11 and 12 are provided. It is regenerated to the input capacitor C1 through Q4 and the body diodes of the high-side switches Q11 and Q13 provided on the second arms 21 and 22. Thereby, zero voltage switching of the low-side switches Q2 and Q4 is possible, and switching loss can be suppressed.

  With the above operation, as shown in FIG. 2, the current of the resonant choke is significantly reduced as compared with the case of the phase shift control shown in FIG. 3, so that loss can be reduced and the resonant choke can be downsized. Further, with the above configuration, ZVS can be realized without using phase shift control, so that it is not necessary to flow a circulating current, and the loss of the primary winding of the switch and the transformer can be reduced. Furthermore, since ZVS is not performed by the energy of the circulating current, the ZVS condition is not influenced by the load, and ZVS can be stably realized at full load or no load, and low noise is achieved even at no load. Since only the current for discharging the parasitic capacitance of the main circuit flows through the second arms 21 and 22, the switches of the second arms 21 and 22 may be small.

  Next, an embodiment of a half-bridge type switching power supply device is shown in FIG. In this switching power supply, a primary arm and a secondary are insulated by a transformer T, a first arm 11 in which two switch elements Q1 and Q2 are connected in series on the primary side, and two capacitors C11 and C12 are connected in series. The first arm 11 and the series circuit 31 are connected in parallel to form a half-bridge circuit, and the midpoint of each of the series circuits 11 and 31 is connected to the primary winding of the transformer T. is there.

  This embodiment is characterized by the following configuration. A second arm 21 is provided in which two switch elements Q11 and Q12 are connected in series. The second arm 21 is connected in parallel with the first arm 11, and a resonance choke L 11 is connected between the midpoint of the first arm 11 and the midpoint of the second arm 21.

  The switching power supply device configured as described above operates as follows. Immediately before the high-side switch Q1 provided on the first arm 11 is turned on, the high-side switch Q11 provided on the second arm 21 is turned on to discharge the parasitic capacitance. The discharged energy moves to the resonance choke L11, and the high side switch Q1 provided in the first arm 11 and the second arm 21 at the timing when the high side switch Q11 provided in the second arm 21 is turned off. It is regenerated to the input capacitor C1 through the body diode of the provided low-side switch Q12. Thereby, zero voltage switching of the high side switch Q1 becomes possible, and switching loss can be suppressed.

  Further, immediately before the low side switch Q2 provided in the first arm 11 is turned on, the low side switch Q12 provided in the second arm 21 is turned on to discharge the parasitic capacitance. The discharged energy moves to the resonance choke L11, and the low side switch Q2 provided in the first arm 11 and the second arm 21 are provided at the timing when the low side switch Q12 provided in the second arm 21 is turned off. Then, it is regenerated to the input capacitor C1 through the body diode of the high side switch Q11. As a result, zero voltage switching of the low-side switch Q2 becomes possible, and switching loss can be suppressed.

  As a result of the above operation, the current of the resonance choke L11 is greatly reduced as compared with the case where the resonance choke L11 is inserted in series with the primary winding of the transformer T, as in the above embodiment. Miniaturization is possible. In addition, since the ZVS is not caused by the energy stored in the resonance choke L11, the ZVS condition is not influenced by the load, and the ZVS can be realized stably at full load or no load, and low noise is achieved even at no load. . Since only the current for discharging the parasitic capacitance of the main circuit flows through the second arm 21, the switch of the second arm 21 may be small.

  The present invention can be applied not only to a bridge-type switching power supply but also to a push-pull type switching power supply apparatus that is the original form. An embodiment of the push-pull type switching power supply device is shown in FIG. In this switching power supply, the primary and secondary are insulated by a transformer T, and in parallel with the input power supply, a series circuit of a first primary winding and a switch element Q1, and a second primary winding and a switch element Q2 A series circuit is connected.

  This embodiment is characterized by the following configuration. The primary winding of the transformer T and the switch elements Q1 and Q2 form two first series circuits 13 and 14, and the rectifier elements D11 and D12 and the switch are connected in parallel with the first series circuits 13 and 14, respectively. Second series circuits 23 and 24, in which the elements Q11 and Q12 are connected in series, are connected. Further, the connection point between the primary winding of the transformer T constituting the first series circuits 13 and 14 and the switch elements Q1 and Q2, the rectifier elements D11 and D12 and the switch elements constituting the second series circuits 23 and 24, respectively. Resonant chokes L11 and L12 are connected between the connection points with Q11 and Q12, respectively.

  The switching power supply device configured as described above operates as follows. Immediately before the switch element Q1 provided in the first series circuit 13 is turned on, the switch element Q11 provided in the second series circuit 23 is turned on to discharge the parasitic capacitance. The discharged energy moves to the resonance choke L11, the switch element Q1 provided in the first series circuit 13 at the timing when the switch element Q11 provided in the second series circuit 23 is turned off, and the second series circuit 23. Is regenerated to the input capacitor C1 through the rectifying element D11 provided in the circuit. Thereby, zero voltage switching of the switch element Q1 becomes possible, and switching loss can be suppressed.

  Also, immediately before the switch element Q2 provided in the first series circuit 14 is turned on, the switch element Q12 provided in the second series circuit 24 is turned on to discharge the parasitic capacitance. The discharged energy moves to the resonance choke L12, and the switch element Q2 provided in the first series circuit 14 and the second series circuit 24 at the timing when the switch element Q12 provided in the second series circuit 24 is turned off. Is regenerated to the input capacitor C1 through the rectifying element D12 provided in Thereby, zero voltage switching of the switch element Q2 becomes possible, and switching loss can be suppressed.

  With the above operation, ZVS can be realized stably at full load or no load, and low noise can be achieved even at no load. Since only the current for discharging the parasitic capacitance of the main circuit flows through the second series circuits 23 and 24 and the resonance chokes L11 and 12, the switch of the second series circuits 23 and 24 and the resonance chokes L11 and 12 Can be small.

  In the present invention, as shown by a push-pull type switching power supply, a series circuit can be configured by a rectifying element and a switch element instead of an arm configured by an even number of switching elements. The present invention can also be applied to a device or a flyback type switching power supply device. A forward type switching power supply is shown in FIG. 6, and a flyback type switching power supply is shown in FIG. In these switching power supplies, the primary and secondary are insulated by a transformer T, one input terminal is connected to one end of the primary winding of the transformer T, and the switch element Q1 is connected in series to the other end. The other input end is connected to the other end of the switch element Q1.

  This embodiment is characterized by the following configuration. A first series circuit 13 is constituted by the primary winding of the transformer T and the switch element Q1, and a second series circuit in which the rectifier element D11 and the switch element Q11 are connected in series with the first series circuit 13 respectively. 23 is connected. Further, between the connection point between the primary winding of the transformer T constituting the first series circuit 13 and the switch element Q1, and the connection point between the rectifier element D11 and the switch element Q11 constituting the second series circuit 23. Further, a resonance choke L11 is connected to each.

  The switching power supply device configured as described above operates as follows. Immediately before the switch element Q1 provided in the first series circuit 13 is turned on, the switch element Q11 provided in the second series circuit 23 is turned on to discharge the parasitic capacitance. The discharged energy moves to the resonance choke L11, and the switch element Q1 provided in the first series circuit 13 and the second series circuit 23 at the timing when the switch element Q11 provided in the second series circuit 23 is turned off. Is regenerated to the input capacitor C1 through the rectifying element D11 provided in the circuit. Thereby, zero voltage switching of the switch element Q1 becomes possible, and switching loss can be suppressed.

  As described above, as in the above-described embodiment, ZVS can be realized stably at full load or no load, and low noise is achieved even at no load. Since only the current for discharging the parasitic capacitance of the main circuit flows through the second series circuit 23 and the resonance choke L11, the switch and the resonance choke L11 of the second series circuit 23 may be small.

  According to the present invention, each of the second series circuits is connected in parallel with the first series circuit, and each resonance choke is provided between the midpoint of the first series circuit and the midpoint of the second series circuit. By being connected, the current of the resonant choke is greatly reduced, so that loss can be reduced and the resonant choke can be downsized.

  Further, according to the above configuration, ZVS can be realized without using phase shift control, so that it is not necessary to flow a circulating current, and the loss of the primary winding of the switch and the transformer can be reduced. Furthermore, since ZVS is not performed by the energy of the circulating current, the ZVS condition is not influenced by the load, and ZVS can be stably realized at full load or no load, and low noise is achieved even at no load.

[BRIEF DESCRIPTION OF THE DRAWINGS] It is a circuit diagram of the best form for implementing invention in the power converter device which concerns on this invention. 1 is a waveform diagram of a current flowing through a resonance choke in the embodiment shown in FIG. It is a wave form diagram of the electric current which flows into the resonance choke in the conventional switching power supply device of a phase shift control system. It is a circuit diagram of an example different from the example. Similarly, it is a circuit diagram of an embodiment different from the embodiment. Similarly, it is a circuit diagram of an embodiment different from the embodiment. Similarly, it is a circuit diagram of an embodiment different from the embodiment. It is a circuit diagram of the conventional full bridge type switching power supply device. It is a wave form diagram of the electric current which flows into the primary winding of the trans | transformer in the conventional switching power supply device of a phase shift control system. It is a wave form diagram of the electric current which flows into the primary winding of the trans | transformer in the conventional switching power supply device of a PWM control system.

Explanation of symbols

11, 12 1st arm 21, 22 2nd arm 13, 14 1st arm 23, 24 2nd arm 31 Series circuit Q1-Q4, Q11-Q14 Switch element L1 Output choke L2, L11, L12 Resonant choke C2 output capacitor
T transformer
D1, D2, D11, D12 Rectifier circuit

Claims (5)

One or more first series circuits with an even number of switching elements connected in series on the primary side are isolated by a transformer between the primary and secondary, and the midpoint of the series circuit is connected to the primary winding of the transformer In the switching power supply device, the second series circuit having an even number of switch elements connected in series is connected in parallel with the first series circuit,
A switching power supply device comprising a resonance choke connected between a midpoint of the first series circuit and a midpoint of the second series circuit. 2. The switching power supply according to claim 1, wherein the first series circuit is provided in two, and the second series circuit is connected in parallel with the first series circuit. The first series circuit is provided, and a third series circuit formed by connecting a plurality of capacitors in series with the first series circuit is connected in parallel. Switching power supply. A switching power supply device in which a primary and a secondary are insulated by a transformer and a switching element is connected in series to the primary winding of the transformer, the switching power supply device includes a first series circuit having the primary winding and the switching element. A second series circuit having a rectifier element and a switch element in parallel with the one series circuit, a connection point between the primary winding and the switch element constituting the first series circuit, and the second series circuit A switching power supply comprising a resonance choke connected between a connection point between a rectifying element and a switch element constituting a circuit. Having two first series circuits, connecting primary windings of transformers constituting the first series circuit, and connecting the second series circuit in parallel with the first series circuit 5. The switching power supply according to claim 4, wherein

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