JP5484818B2 - Power supply - Google Patents

Description

  The present invention relates to a step-down power supply device that uses a switching control method.

  In this type of power supply device, for example, as shown in FIG. 1 of Patent Document 1 and FIG. 3A of Patent Document 2, it is arranged on one of a pair of power supply lines to which DC power is supplied. Switch, a reactor arranged on one side of the power line, a commutation diode connected between the power line between the switch and the reactor, and a smoothing capacitor connected between the power line after the reactor. And is connected to a load by a power supply line after the smoothing capacitor. Based on the on / off operation of the switch, the stepped down output power is supplied to the load side.

  In such a switch that is controlled to be turned on / off, hard switching that directly (forcefully) cuts off the voltage / current on the power supply line causes a large switching loss and causes various problems. In addition, an auxiliary circuit for performing soft switching that switches the switch at zero voltage or zero current is provided to reduce switching loss.

JP 7-123707 A JP-A-9-266665

  However, in addition to the basic configuration as the power supply device described above, the auxiliary circuit shown in FIG. 3A of Patent Document 1 includes an auxiliary switch, an auxiliary transformer, a resonance inductor, a resonance capacitor, A diode is used. In addition, the auxiliary circuit shown in FIG. 1 of Patent Document 2 is replaced with a tapped inductor, a diode is added, and a parasitic capacitance of the power switch is used.

  In other words, the former auxiliary circuit has a large number of circuit elements, and in particular, many coil elements such as an auxiliary transformer and a resonance inductor that increase the size of the circuit are used. In addition, since the latter auxiliary circuit uses a part of the tapped inductor for the auxiliary circuit, a large current flows in the inductor functioning as the auxiliary circuit as in the basic component of the power supply device. . For this reason, for example, a welding power supply device that handles a large current has a large loss and is not suitable for a welding power supply device.

  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 device that can reduce the switching loss with a configuration that can be downsized and has high applicability to a large current. It is to provide.

In order to solve the above-mentioned problem, the invention according to claim 1 is directed to a switch disposed on a pair of power supply lines to which a DC power is supplied, a reactor disposed on the power supply line, the switch, and the reactor. And a commutation diode connected between the power lines between the power lines, and a power supply device that supplies, as output power, power generated on the subsequent stage side of the reactor by on / off control of the switch to the load. a primary reactor which is disposed on the power line, is configured by coupling reactor with a secondary reactor which is separated from the primary side reactor, the secondary reactor and, Oh window operation of the switch the switch in accordance with an auxiliary capacitor for electric discharge based on the voltage generated by the secondary reactor, the auxiliary capacitor of the discharge electric state An auxiliary circuit for the inter-terminal voltage when off small, the auxiliary circuit, the auxiliary capacitor connected in parallel with the switch, on the basis of the voltage generated on the secondary side reactor during the ON period of the switch The auxiliary capacitor is discharged and the auxiliary capacitor is discharged through the secondary reactor, and the voltage applied between the terminals of the switch is changed by replacing the applied voltage when the switch is turned off with the charging voltage of the auxiliary capacitor. The gist is to reduce it .

In this invention, the reactor used for the basic configuration of the power supply device is the primary reactor of the coupled reactor, and the auxiliary circuit includes the secondary reactor of the coupled reactor and the auxiliary capacitor. The auxiliary circuit based on the voltage with the switch Oh window operation occurs on the secondary side reactor to electrostatic discharge auxiliary capacitor, the terminal voltage at the time of switch-off by means of the auxiliary capacitor discharge conducting state The operation is reduced to reduce the switching loss. In other words, in the auxiliary circuit for reducing the switching loss, the coil element that causes the circuit size to be increased can be configured only by the secondary side reactor, which contributes to downsizing, and the reactor is separated from the primary side. The current flowing through the secondary reactor, that is, the auxiliary circuit, can be set small, and the applicability to a welding power source apparatus that handles a large current is also high.

  In this invention, the auxiliary circuit is configured by connecting the auxiliary capacitor in parallel with the switch, and the auxiliary capacitor is discharged based on the voltage generated in the secondary side reactor during the switch ON period, and when the next switch is OFF. The voltage between the terminals of the switch is reduced by replacing the applied voltage with the charging voltage of the auxiliary capacitor. That is, the auxiliary circuit for reducing the switching loss can be realized with a simple configuration in such a connection mode using the secondary reactor and the auxiliary capacitor.

The invention according to claim 2, in the power supply device according to claim 1, wherein the auxiliary circuit comprises a first diode for charging said auxiliary capacitor during the off period of the switch, the ON period of the switch The gist of the present invention is to provide a second diode for discharging based on a voltage generated in the secondary reactor.

  In the present invention, the auxiliary circuit includes a first diode that charges the auxiliary capacitor during the switch off period and a second diode that discharges based on the voltage generated in the secondary reactor during the switch on period. Is done. That is, the auxiliary circuit can be simply configured by using two more diodes for the secondary reactor and the auxiliary capacitor.

  ADVANTAGE OF THE INVENTION According to this invention, the power supply device which can reduce a switching loss with the structure which can be reduced in size and has high applicability to large current can be provided.

It is a circuit diagram of the power supply device in a 1st embodiment. It is a block diagram of a coupling reactor. It is a wave form diagram which shows the voltage and electric current change (at the time of OFF) between switch both terminals. It is a wave form diagram which shows the voltage and electric current change (at the time of ON) between switch both terminals. It is a circuit diagram of the power supply device in 2nd Embodiment. It is a circuit diagram which shows the example of a change of a power supply device. It is a circuit diagram which shows the example of a change of a power supply device.

(First embodiment)
A first embodiment of the present invention will be described below with reference to the drawings.
As shown in FIG. 1, the power supply device 10 of the present embodiment is a step-down switching regulator, and as a basic configuration thereof, a power supply line on the ground side of a pair of power supply lines 11 a and 11 b to which a DC power supply E is supplied. Connected between the switch S1 disposed on 11b, the primary reactor L1P of the coupled reactor L1 disposed on the high-potential power line 11a, and the power lines 11a and 11b between the switch S1 and the reactor L1P. Commutation diode D2 and a smoothing capacitor C1 connected between power supply lines 11a and 11b after the reactor L1P.

  In this embodiment, the switch S1 is made of an IGBT, the emitter side is connected to the negative terminal (ground terminal) of the DC power source E, and the reverse conducting diode D1 is connected between the collector and the emitter. The switch S1 is subjected to switching control based on a control pulse signal input to the gate. In the ON period of the switch S1, output power based on the DC power supply E is generated, and in the OFF period of the switch S1, output power is generated based on the electromagnetic energy accumulated in the primary reactor L1P of the coupling reactor L1 in the previous ON period. By such on / off control of the switch S1, the power supply apparatus 10 performs a step-down operation, and the stepped-down output power is supplied to the load R through the smoothing capacitor C1.

  Further, the power supply device 10 includes an auxiliary circuit (lossless snubber circuit) 12 for reducing the switching loss of the switch S1, and the auxiliary circuit 12 includes two secondary reactors L1S of the coupling reactor L1. Auxiliary diodes D3 and D4 and an auxiliary capacitor C2.

  One end of the secondary reactor L1S is connected to the ground-side power line 11b between the commutation diode D2 and the smoothing capacitor C1, and the other end is connected to the anode of the auxiliary diode D4. Between the switch S1 and the commutation diode D2, the cathode of the auxiliary diode D3 is connected to the high-potential-side power line 11a, and the anode is connected to the ground-side power line 11b via the auxiliary capacitor C2. The cathode of the auxiliary diode D4 is connected between the auxiliary diode D3 and the auxiliary capacitor C2.

  Incidentally, as shown in FIG. 2, the coupling reactor L1 of the present embodiment is such that the primary side reactor L1P and the secondary side reactor L1S are separated (insulated), and are aligned in the axial direction of the same rod-shaped iron core Lx. The coupling coefficient is set to be sufficiently smaller than 1. Thereby, the charging current of the auxiliary capacitor C2 flowing through the secondary side reactor L1S is limited. Further, the winding ratio between the primary side reactor L1P and the secondary side reactor L1S is made larger than 1, so that the secondary side reactor L1S is wound more and the auxiliary capacitor based on the voltage generated in the secondary side reactor L1S. The charging voltage for charging C2 is set to be sufficiently charged to be equal to or higher than the power supply voltage of the DC power supply E.

  In the power supply device 10 having such a configuration, in the basic configuration portion as a switching regulator including the switch S1, the primary side reactor L1P, the commutation diode D2, and the smoothing capacitor C1, the switch S1 is turned on and off based on the input of the control pulse signal. Reduced output power is generated, and the voltage value of the output power is adjusted by adjusting the on-pulse width of the control pulse signal.

  Further, regarding the operation of the auxiliary circuit 12 accompanying the on / off operation of the switch S1, when the switch S1 is turned on, the input side (the side indicated by the dot “•” in FIG. 1) is positive to the primary side reactor L1P. A counter electromotive voltage is generated, and a voltage that is positive on the input side is also generated in the secondary reactor L1S. Then, a charging current flows to the auxiliary capacitor C2 via the auxiliary diode D4, and finally the charging voltage of the auxiliary capacitor C2 is clamped to the power supply voltage of the DC power supply E.

  Therefore, when the switch S1 is turned off, the potential difference between both terminals of the switch S1 is zero, or the potential difference is extremely small, so that substantially zero voltage switching (soft switching) is realized as shown in FIG. Switching loss in the switch S1 is sufficiently reduced. Then, the charged charge of the auxiliary capacitor C2 in the charged state is released through the auxiliary diode D3 with the release of the electromagnetic energy of the primary side reactor L1P during this off period.

  Further, when the switch S1 is turned on, there is a concern that a current having a high peak value flows through the switch S1 due to the charging current of the auxiliary capacitor C2. In this embodiment, the coupling coefficient of the coupling reactor L1 is sufficiently smaller than 1. Since the leakage inductance is increased, as shown in FIG. 4, the peak value of the current flowing through the switch S1 immediately after the switch S1 is turned on is kept low. Note that it is possible to reduce the switching loss when the switch S1 is turned on by making the ON edge of the control pulse signal gentle and making the rise of the switch S1 gentle as shown by the broken line in FIG.

Next, characteristic effects of the present embodiment will be described.
(1) In the present embodiment, the reactor used for the basic configuration of the power supply apparatus 10 is the primary reactor L1P of the combined reactor L1, and the auxiliary circuit 12 includes the secondary reactor L1S of the combined reactor L1 and the auxiliary capacitor C2. Become. The auxiliary circuit 12 is configured by connecting the auxiliary capacitor C2 between the power supply lines 11a and 11b between the switch S1 and the commutation diode D2, and is based on the voltage generated in the secondary side reactor L1S during the ON period of the switch S1. Thus, the auxiliary capacitor C2 is charged, and the voltage across the terminals of the switch S1 is reduced in advance to prepare for the next switch S1 to be turned off, thereby reducing the switching loss. In other words, in the auxiliary circuit 12 for reducing the switching loss, the coil element that particularly increases the size of the circuit can be configured only by the secondary side reactor L1S, which can contribute to downsizing, and the reactor L1S is separated from the primary side. Therefore, the current flowing through the secondary reactor L1S, that is, the auxiliary circuit 12, can be set small, and the power supply apparatus can be provided with high applicability to a welding power supply apparatus that handles a large current.

  (2) The auxiliary circuit 12 of the present embodiment can be realized with a simple configuration by the above-described connection mode using the secondary side reactor L1S, the auxiliary capacitor C2, and the two diodes D3 and D4.

(Second Embodiment)
Hereinafter, a second embodiment of the present invention will be described with reference to the drawings.
As shown in FIG. 5, in the power supply device 10a of the present embodiment, the basic components as a switching regulator by the switch S1, the primary reactor L1P of the coupling reactor L1, the commutation diode D2, and the smoothing capacitor C1 are the same. The configuration of the auxiliary circuit 12a is changed.

  That is, the auxiliary circuit 12a includes a secondary reactor L1S of the coupling reactor L1, two auxiliary diodes D3 and D4, and an auxiliary capacitor C2. The anode of the auxiliary diode D4 is connected to the collector of the switch S1, and the cathode is auxiliary. The capacitor C2 is connected to the emitter of the switch S1. One end of the secondary side reactor L1S is connected between the auxiliary diode D4 and the auxiliary capacitor C2, and the other end is connected to the high potential side power line 11a via the auxiliary diode D3.

  Incidentally, as shown in FIG. 2, the coupling reactor L1 of the present embodiment also separates (insulates) the primary side reactor L1P and the secondary side reactor L1S, and is aligned in the axial direction of the same rod-shaped iron core Lx. The coupling coefficient is set to be sufficiently smaller than 1. Thereby, the charging current of the auxiliary capacitor C2 flowing through the secondary side reactor L1S is limited. Further, the winding ratio between the primary side reactor L1P and the secondary side reactor L1S is made larger than 1, so that the secondary side reactor L1S is wound more and the auxiliary capacitor based on the voltage generated in the secondary side reactor L1S. The charging voltage at which C2 is discharged is set to be discharged to approximately zero.

  Therefore, regarding the operation of the auxiliary circuit 12a accompanying the on / off operation (step-down operation) of the switch S1, when the switch S1 is turned on, a back electromotive voltage having a positive input side is generated in the primary side reactor L1P. The secondary side reactor L1S also generates a positive voltage on the input side. Then, the charged charge of the auxiliary capacitor C2 charged in the previous off period is discharged through the secondary side reactor L1S and the auxiliary diode D3, and is sufficiently discharged until the charge becomes substantially zero by the next off.

  Therefore, when the switch S1 is turned off, the voltage applied to the switch S1 becomes the charging voltage of the auxiliary capacitor C2 to charge the capacitor C2. Therefore, the potential difference between both terminals of the switch S1 is zero, or the potential difference is extremely high. Even in this embodiment, substantially zero voltage switching (soft switching) is realized. Thereby, the switching loss at the time of OFF is fully reduced.

  Incidentally, the power supply device 10b shown in FIG. 6 is provided with a similar configuration in the auxiliary circuit 12a. On the other hand, in place of the smoothing capacitor C1 used in the basic component portion as a regulator, the power supply device 10b is connected to the downstream of the coupling reactor L1 (primary side reactor L1P). An output reactor L2 is arranged. That is, since the power supply device 10a shown in FIG. 5 is provided with the smoothing capacitor C1, it is suitable as a power supply device for a device that requires constant voltage output, and the power supply device 10b shown in FIG. 6 is provided with the output reactor L2. Therefore, it is suitable as a power supply device for a device that requires constant current output. The power supply device 10c shown in FIG. 7 is configured using both the smoothing capacitor C1 and the output reactor L2, and is suitable as a power supply device for a device that requires both constant voltage and constant current.

Next, characteristic effects of the present embodiment will be described.
(1) In this embodiment, the reactor used for the basic configuration of the power supply device 10a (10b, 10c) is the primary reactor L1P of the coupled reactor L1, and the auxiliary circuit 12a is the secondary reactor L1S and the auxiliary capacitor of the coupled reactor L1. C2. The auxiliary circuit 12a is configured by connecting the auxiliary capacitor C2 in parallel with the switch S1, and the auxiliary capacitor C2 is discharged based on the voltage generated in the secondary reactor L1S during the ON period of the switch S1, and the next switch S1 Since the applied voltage at the time of turning off is replaced with the charging voltage of the auxiliary capacitor C2, the voltage between the terminals of the switch S1 is reduced, and the switching loss is reduced. In other words, in the auxiliary circuit 12a for reducing the switching loss, the coil element that particularly increases the size of the circuit can be configured only by the secondary side reactor L1S, which can contribute to downsizing, and the reactor L1S is separated from the primary side. Therefore, the secondary side reactor L1S, that is, the current flowing through the auxiliary circuit 12a can be set small, and the power supply apparatus having high applicability to a welding power supply apparatus that handles a large current can be provided.

  (2) The auxiliary circuit 12a of the present embodiment can be realized with a simple configuration by the above connection mode using the secondary side reactor L1S, the auxiliary capacitor C2, and the two diodes D3 and D4.

In addition, you may change embodiment of this invention as follows.
-Although the auxiliary circuits 12 and 12a of the said embodiment were comprised by the secondary side reactor L1S, the auxiliary capacitor C2, and two diodes D3 and D4, the element and connection which comprise are not restricted to this, A slight change is also included. . Further, the configuration of the coupling reactor L1 is not limited to this.

In the above embodiment, the IGBT is used for the switch S1, but a switching element other than the IGBT may be used.
The DC power supply E of the above embodiment includes a DC power supply itself or a circuit obtained by rectifying and smoothing a (commercial) AC power supply.

  DESCRIPTION OF SYMBOLS 10,10a, 10b, 10c ... Power supply device, 11a, 11b ... Power supply line, 12, 12a ... Auxiliary circuit, C2 ... Auxiliary capacitor, D2 ... Commutation diode, D3 ... Auxiliary diode (second diode), D4 ... Auxiliary diode (First diode), E ... DC power source, L1 ... coupled reactor, L1P ... primary side reactor, L1S ... secondary side reactor, R ... load, S1 ... switch.

Claims (2)

A switch disposed on a pair of power supply lines to which DC power is supplied, a reactor disposed on the power supply line, and a commutation diode connected between the power supply lines between the switch and the reactor. , A power supply device that supplies, as output power, power generated on the downstream side of the reactor by on / off control of the switch,
The reactor is constituted by a combined reactor including a primary side reactor disposed on the power line, and a secondary side reactor separated from the primary side reactor,
Said switch in said has a secondary reactor, an auxiliary capacitor for electric discharge based on the voltage generated by the O window operation wherein the secondary reactor with the said switch, the auxiliary capacitor of the discharge conducting state With an auxiliary circuit that reduces the voltage across the terminals when
The auxiliary circuit connects the auxiliary capacitor in parallel with the switch, and discharges the auxiliary capacitor based on a voltage generated in the secondary reactor during an ON period of the switch and discharges the auxiliary capacitor to the second circuit. A power supply apparatus, characterized in that the voltage applied between the terminals of the switch is reduced by changing the applied voltage when the next switch is turned off to the charging voltage of the auxiliary capacitor . The power supply device according to claim 1 ,
The auxiliary circuit includes a first diode for charging the auxiliary capacitor during an off period of the switch, and a second diode for discharging based on a voltage generated in the secondary side reactor during an on period of the switch; A power supply device comprising:

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