JP5919804B2 - Switching power supply circuit - Google Patents

Description

  The present invention relates to an inductor, and more particularly to a switching power supply circuit that can be employed as a pair of power factor correction circuits operating in an interleaved manner.

  Non-Patent Document 1 discloses a pair of power factor correction circuits operating in a critical mode and interleaving (hereinafter simply referred to as “interleaved power factor correction circuits”). In the interleave type power factor correction circuit, a pair of boost type chopper circuits are connected in parallel and have a reactor, a diode, and a switching element.

  Non-Patent Document 2 describes a case where a pair of reactors are inductively coupled in an interleaved power factor correction circuit.

Mamoru Kitamura, “Critical mode / interleaved PFC IC R2A20112 that can create a 1.5kW low noise harmonic power supply”, Transistor Technology May 2008 issue, CQ Publishing Co., Ltd., August 2008, pp. 176 to 184 Wei Wen and Yim-Shu Lee, “A Two-channel Interleaved Boost Converter with Reduced Core Loss and Copper Loss”, 2004-35th Annual IEEE Power Electronics Specialists Conference, 2004.

  Improving the ripple of the direct current input to the interleave type power factor correction circuit leads to a reduction in reactor loss. Non-Patent Document 2 describes the ripple improvement of the input current when a pair of reactors are inductively coupled with the same polarity in the interleaved power factor correction circuit, but there is still room for ripple improvement.

  SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to reduce the reactor loss by reducing the ripple of the direct current input to the interleaved power factor correction circuit while reducing the size of the interleave type power factor correction circuit.

  The switching power supply circuit (3) according to the present invention includes a low power supply line (LL), a high power supply line (LH), a first reactor (L3), a second reactor (L1), and a third reactor (L2). A first diode (D1), a second diode (D2), a first switching element (S1), a second switching element (S2), a first capacitor (C), and a second capacitor ( Cf).

  The high power line is applied with a higher potential than the low power line.

  The first reactor has one end connected to the high power line and the other end. The second reactor has one end connected to the other end of the first reactor and the other end. The third reactor has one end connected to the other end of the first reactor and the other end.

  The first diode has a cathode and an anode connected to the other end of the second reactor. The second diode has a cathode and an anode connected to the other end of the third reactor.

  The first switching element is provided between the other end of the second reactor, the anode of the first diode, and the low power supply line. The second switching element is provided between the other end of the third reactor, the anode of the second diode, and the low power supply line.

  The first capacitor has one end connected to the cathode of the first diode and the cathode of the second diode, and the other end connected to the low power line. The second capacitor has one end connected to the other end of the first reactor and the other end connected to the low power line.

  The inductance value (L) of the second reactor is equal to the inductance value (L) of the third reactor. The first reactor, the second reactor, and the third reactor are inductively coupled with the same polarity when viewed from the high power line. A mutual inductance between the first reactor and the second reactor is equal to a mutual inductance between the first reactor and the third reactor.

  Preferably, the first reactor, the second reactor, and the third reactor are formed in the same core.

  According to the switching power supply circuit of the present invention, the first reactor and the second capacitor form a bypass for the harmonics flowing through the second reactor and the third reactor, and therefore, between the high power line and the low power line. The ripple of the direct current supplied can be reduced, and the loss of the reactor in the first to third reactors can be reduced.

  In addition, the switching power supply circuit is reduced in size.

It is a circuit diagram which shows the structure of the interleave type | mold power factor improvement circuit concerning one embodiment of this invention. It is a graph which shows the characteristic of an interleave type power factor improvement circuit. It is a circuit diagram which shows the structure of the 1st reference example of an interleave type power factor improvement circuit. It is a circuit diagram which shows the structure of the 2nd reference example of an interleave type power factor improvement circuit.

  The interleaved power factor correction circuit 5 shown in FIG. 3 includes switching elements S1 and S2, diodes D1 and D2, an inductor 9, and a capacitor C. A load 4 is connected to the capacitor C in parallel.

  The rectifier circuit 2 receives an AC input current Iin from the AC power source 1. The rectifier circuit 2 rectifies the input current Iin, for example, by full-wave rectification and supplies the direct current Id to the inductor 9.

  The inductor 9 has reactors L1 and L2. Reactors L1 and L2 both have one end connected to high power line LH and the other end.

  The anode of diode D1 is connected to the other end of reactor L1, and the anode of diode D2 is connected to the other end of reactor L2.

  The switching element S1 is provided between the other end of the reactor L1, the anode of the diode D1, and the low power supply line LL. The switching element S2 is provided between the other end of the reactor L2, the anode of the diode D2, and the low power line LL.

  Capacitor C has one end connected to the cathodes of both diodes D1 and D2, and the other end connected to low power supply line LL.

  In the inductor 9, black circles indicate the polarity of inductive coupling between the reactors L1 and L2. Reactors L1 and L2 are inductively coupled with the same polarity as viewed from high power line LH. The black circle of reactor L1 and the black circle of reactor L2 are shown adjacent to each other.

  Reactors L1 and L2 each have a self-inductance value L and are inductively coupled with each other with a mutual inductance value M.

  In order to drive the interleave type power factor correction circuit 3 configured as described above by the critical mode type interleave method, signals G1 and G2 are supplied to the switching elements S1 and S2, respectively, and conduction / non-conduction is controlled. Is done.

  Specifically, currents I1 and I2 flowing through reactors L1 and L2 are detected, and a timing at which each takes a minimum value is detected by a known technique. The control unit 6 may generate the switching signals G1 and G2 based on the voltage Vdc across the capacitor C and its command value Vdc * and the above timing. Since a technique for generating the switching signals G1 and G2 and driving the interleave type power factor correction circuit 5 by the critical mode type interleaving method based on the signals G1 and G2 is a known technique, a detailed description is omitted here. .

  FIG. 2A is a graph showing the waveforms of the direct current Id and the currents I1 and I2 flowing through the circuit of FIG. When the pair of reactors L1 and L2 are inductively coupled with the same polarity as viewed from the rectifier circuit 2 side that supplies the direct current Id, the portion where the slope of the currents I1 and I2 decreases is reduced. is there. Thereby, the ripple of the direct current Id is reduced.

  The circuit shown in FIG. 4 has a configuration in which a reactor L0 is added between the path of the input current Iin, that is, between the rectifier circuit 2 and the AC power supply 1 in the circuit shown in FIG. The reactor L0 has an effect of suppressing a change in the direct current Id via the rectifier circuit 2. However, since the inductor 9 is on the side of the capacitor C with respect to the rectifier circuit 2, the reactor L0 is on the side of the AC power source 1 with respect to the rectifier circuit 2, and therefore, it is necessary to separately provide it on the AC power source 1 side. And increase in the size of the entire circuit.

  The interleave type power factor correction circuit 3 shown in FIG. 1 has a configuration in which the inductor 9 of the interleave type power factor improvement circuit 5 shown in FIG. 3 is replaced with an inductor 10 and a capacitor Cf is added.

  Specifically, the inductor 10 has reactors L1, L2, and L3. One end of the reactor L3 is connected to the high power line LH. One end of the reactor L1 and one end of the reactor L2 are both connected to the other end of the reactor L3.

  The anode of diode D1 is connected to the other end of reactor L1, and the anode of diode D2 is connected to the other end of reactor L2.

  The switching element S1 is provided between the other end of the reactor L1, the anode of the diode D1, and the low power supply line LL. The switching element S2 is provided between the other end of the reactor L2, the anode of the diode D2, and the low power line LL.

  The capacitor C is connected between the cathode of the diode D1, the cathode of the diode, and the low power supply line LL.

  Capacitor Cf is connected between the other end of reactor L3 and low power supply line LL.

  Here, the inductance value L of the reactor L1 is equal to the inductance value L of the reactor L2. Reactors L1, L2, and L3 are inductively coupled with the same polarity as viewed from high power line LH. The mutual inductance of reactors L1 and L3 is equal to the mutual inductance of reactors L2 and L3. Reactors L1, L2, and L3 can be formed of coils wound around the same core.

  Since a technique for generating the switching signals G1 and G2 and driving the interleave type power factor correction circuit 3 by the critical mode type interleaving method based on the signals G1 and G2 is a known technique, a detailed description is omitted here. .

  FIG. 2B is a graph showing the waveforms of the direct current Id and the currents I1 and I2 flowing through the circuit of FIG. Reactor L3 and capacitor Cf form a bypass for the harmonics of direct current Id supplied between high power line LH and low power line LL, so that ripple of direct current Id is reduced. Thereby, the reactor loss in a 1st thru | or 3rd reactor can be reduced.

  In addition, since the first to third reactors can be realized in one core, the inductor 10 is made smaller than the case where the inductor 9 and the reactor L0 are provided separately.

  FIG. 2C is a graph showing the waveforms of the direct current Id in FIG. 2A as the current Id1 and the direct current Id in FIG. 2B as the current Id2. In the graph, it is understood that the ripple is reduced in the current Id2 than in the current Id1.

  As described above, the ripple of the direct current Id is reduced as compared with the case where the pair of reactors shown in Non-Patent Document 2 and the like are inductively coupled. Moreover, the size can be reduced as compared with the case where the reactor L0 is simply used on the AC power supply 1 side. And if reactor L1, L2, L3 is formed in the same core, it can reduce in size.

LL Low power line LH High power line L1, L2, L3 Reactor D1, D2 Diode S1, S2 Switching element C, Cf Capacitor

Claims (2)

A low power line (LL);
A high power line (LH) to which a higher potential is applied than the low power line;
A first reactor (L3) having one end connected to the high power line and the other end;
A second reactor (L1) having one end connected to the other end of the first reactor and the other end;
A third reactor (L2) having one end connected to the other end of the first reactor and the other end;
A first diode (D1) having a cathode and an anode connected to the other end of the second reactor;
A second diode (D2) having a cathode and an anode connected to the other end of the third reactor;
A first switching element (S1) provided between the other end of the second reactor and the anode of the first diode and the low power line;
A second switching element (S2) provided between the other end of the third reactor and the anode of the second diode and the low power line;
A first capacitor (C) having one end connected to the cathode of the first diode and the cathode of the second diode and the other end connected to the low power line;
A second capacitor (Cf) having one end connected to the other end of the first reactor and the other end connected to the low power line;
With
The inductance value (L) of the second reactor is equal to the inductance value (L) of the third reactor,
The first reactor, the second reactor, and the third reactor are inductively coupled with the same polarity as viewed from the high power line,
A switching power supply circuit (3), wherein a mutual inductance between the first reactor and the second reactor is equal to a mutual inductance between the first reactor and the third reactor.   The switching power supply circuit (3) according to claim 1, wherein the first reactor, the second reactor, and the third reactor are formed in the same core.

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