JP6335826B2 - One-converter switching power supply - Google Patents

Description

  The present invention relates to a one-converter type switching power supply device in which a power factor correction circuit and a converter are integrated.

  As a conventional one-converter type switching power supply, for example, the one described in Patent Document 1 is known. As shown in FIG. 11, this conventional switching power supply 10 includes a circuit in which a first switching element Q1 and a second switching element Q2 are connected in series via a middle point P10, and a first circuit connected in parallel to the first switching element Q1 and the second switching element Q2. A circuit in which 3 switching elements Q3 and 4th switching element Q4 are connected in series via a midpoint P11, and a first diode D6 and a second diode D7 connected in parallel to each other in series via a midpoint P12 And a capacitor C4 connected in parallel therewith, and a control unit 11 for controlling the switching elements Q1 to Q4.

  Further, the switching power supply device 10 is connected to a circuit formed by connecting a capacitor C5, an inductor L4, and a primary winding T1 of the transformer T connected in series between the midpoint P10 and the midpoint P11, and the midpoint P12. And an inductor L3. An AC power supply E that supplies an input voltage to the switching power supply device 10 is connected between the inductor L3 and the midpoint P10. Further, the capacitor C5 and the inductor L4 constitute a resonance circuit.

  The switching power supply 10 further rectifies and smoothes the voltage induced in the secondary windings T2a and T2b of the transformer T, thereby generating a secondary side circuit (diode) that generates a DC output voltage to be supplied to the load 20 D8a, D8b, inductor L5, capacitor C6) are also provided.

  The control unit 11 controls switching of the switching elements Q1 to Q4 (switching from on to off and switching from off to on) based on the PFC voltage and the output voltage.

JP 2011-217666 A

  However, the conventional switching power supply device 10 has a problem that a loss occurs in the first diode D6 and the second diode D7 for feeding back an alternating current, resulting in a reduction in efficiency. Further, the switching power supply device 10 has a problem that it is difficult to reduce the size because of the large number of parts.

  This invention is made | formed in view of the said situation, The place made into the subject is providing the switching power supply device which is highly efficient rather than before, and there are few number of parts.

  In order to solve the above-described problems, a switching power supply according to the present invention includes a first series connection body in which a first switching element and a second switching element are connected in series via a first middle point, and a first series connection. A second series connection body connected in parallel to the body, the third switching element and the fourth switching element connected in series via the second midpoint, and a force connected in parallel to the first and second series connection bodies A rate improving capacitor, a transformer having a primary winding connected between the first and second midpoints, a secondary circuit for rectifying and smoothing a voltage induced in the secondary winding of the transformer, and a first An inductor having one end connected to the midpoint; a capacitor having one end connected to the other end of the inductor; and a control unit that controls the first, second, third, and fourth switching elements, and the other end of the capacitor And the second midpoint An AC power source can be connected to the control unit; a) a first control for turning on / off the first switching element while turning off the second and third switching elements and turning on the fourth switching element; B) second control for turning off the first switching element and the fourth switching element, and turning on / off the third switching element while turning on the second switching element; c) turning off the first and third switching elements; The third control for turning on the fourth switching element is repeatedly executed.

  According to this configuration, since there is no need to provide a current feedback diode on the primary side, loss can be reduced and higher efficiency can be achieved than in a conventional switching power supply device. Further, according to this configuration, since the number of parts on the primary side excluding the AC power supply and the control unit is only 7, the size can be reduced as compared with the conventional switching power supply device (number of parts is 10).

  As the first, second, third and fourth switching elements, for example, a MOSFET including a body diode can be used.

  According to the present invention, it is possible to provide a switching power supply apparatus that is more efficient than the prior art and has a reduced number of parts.

1 is a circuit diagram of a switching power supply device according to the present invention. It is an operation | movement waveform diagram of the switching power supply device which concerns on this invention. It is an expanded operation waveform figure of the positive half term of the switching power supply concerning the present invention. It is a figure which shows the current pathway in the states P1-P3 of the positive half term of the switching power supply device which concerns on this invention. It is a figure which shows the current pathway in the states P4-P6 of the positive half-period of the switching power supply device which concerns on this invention. It is a figure which shows the electric current path in the state P7 of the positive half-period of the switching power supply device which concerns on this invention. It is an expansion operation waveform figure of the negative half of the switching power supply concerning the present invention. It is a figure which shows the current pathway in the states N1-N3 of the negative half-period of the switching power supply which concerns on this invention. It is a figure which shows the electric current path in state N4-N6 of the negative half-period of the switching power supply device which concerns on this invention. It is a figure which shows the electric current path in the state N7 of the negative half period of the switching power supply device which concerns on this invention. It is a circuit diagram of the conventional switching power supply device.

  Embodiments of a one-converter switching power supply device according to the present invention will be described below with reference to the accompanying drawings.

  FIG. 1 shows a one-converter type switching power supply device 1 according to an embodiment of the present invention. The switching power supply device 1 generates a DC output voltage Vout from an input voltage Vin supplied from an AC power supply E such as a commercial system and supplies it to a load 20.

  As shown in FIG. 1, the switching power supply device 1 according to the present embodiment includes a first series connection body 2 in which a first switching element Q1 and a second switching element Q2 are connected in series via a middle point P1, and this Are connected in parallel to each other, and a full bridge circuit 4 including a second series connection body 3 in which a third switching element Q3 and a fourth switching element Q4 are connected in series via a middle point P2.

  In this embodiment, MOSFETs (Metal Oxide Semiconductor Field Effect Transistors) are used as the switching elements Q1 to Q4. Each of the switching elements Q1 to Q4 includes body diodes (parasitic diodes) D1 to D4, respectively. The cathode of the body diode D1 is connected to the drain of the first switching element Q1. The anode of the body diode D1 is connected to the source of the first switching element Q1. The same applies to switching elements Q2 to Q4 and body diodes D2 to D4.

  The switching power supply device 1 further includes a power factor improving capacitor C3. The capacitor C3 is connected in parallel to the full bridge circuit 4 (first series connection body 2, second series connection body 3). More specifically, one end of the capacitor C3 is connected to the drains of the switching elements Q1, Q3, and the other end of the capacitor C3 is connected to the sources of the switching elements Q2, Q4.

  The switching power supply device 1 further includes an inductor L1 and a capacitor C1 connected in series thereto. The inductor L1 has one end connected to the midpoint P1 and the other end connected to one end of the capacitor C1.

  The AC power supply E that supplies the input voltage Vin to the switching power supply device 1 is connected between the other end of the capacitor C1 and the middle point P2. In the present specification, the polarity of the input voltage Vin is “positive” when the potential at the other end of the capacitor C1 is higher than the potential at the midpoint P2, and the potential at the other end of the capacitor C1 is higher than the potential at the midpoint P2. When the input voltage Vin is low, the polarity of the input voltage Vin is “negative”.

  The switching power supply device 1 further includes a transformer T. The transformer T includes a primary winding T1 and two secondary windings T2a and T2b. The primary winding T1 has one end (the end marked with ● in FIG. 1) connected to the midpoint P1, and the other end connected to the midpoint P2. Further, the other end of the secondary winding T2a (the end portion not marked with ●) is connected to one end (the end portion marked with ●) of the secondary winding T2b.

  The switching power supply device 1 further includes a secondary side circuit 5 that generates a DC output voltage Vout to be supplied to the load 20 by rectifying and smoothing a voltage induced in the secondary windings T2a and T2b of the transformer T. ing. The secondary circuit 5 includes a diode D5a whose anode is connected to one end of the secondary winding T2a, a diode D5b whose anode is connected to the other end of the secondary winding T2b, and one end of which is the cathode of the diodes D5a and D5b. And the capacitor C2 having one end connected to the other end of the inductor L2 and the other end connected to the other end of the secondary winding T2a (one end of the secondary winding T2b). Yes. The voltage generated at both ends of the capacitor C2 is supplied to the load 20 as the output voltage Vout.

  The switching power supply device 1 further includes a control unit 6 composed of a microcomputer or the like. The control unit 6 controls switching of the switching elements Q1 to Q4 based on the input voltage Vin, the output voltage Vout, and the voltage at one end of the capacitor C3 (hereinafter referred to as a DC link voltage).

  Next, the control of the switching elements Q1 to Q4 by the control unit 6 in the switching power supply device 1 according to the present embodiment will be described.

The controller 6 turns off the second switching element Q2 and the third switching element Q3 in both the positive half period in which the polarity of the input voltage Vin is positive and the negative half period in which the polarity of the input voltage Vin is negative. A first control for turning on / off the first switching element Q1 while turning on the four switching elements Q4, and b) a third control while turning off the first switching element Q1 and the fourth switching element Q4 and turning on the second switching element Q2. The second control for turning on / off the switching element Q3 and the third control for c) turning off the first switching element Q1 and the third switching element Q3 and turning on the second switching element Q2 and the fourth switching element Q4 are repeatedly executed. To do. Thereby, states P1 to P7 shown in Table 1 are created in the positive half-period, and states N1 to N7 shown in Table 2 are created in the negative half-period (see FIGS. 2, 3, and 7).

  The duty ratios of the switching elements Q1 to Q4 vary according to the DC link voltage and the voltage value of the input voltage Vin (see FIG. 2). However, in FIG. 3 and FIG. Yes. Further, the current flowing through each of the switching elements Q1 to Q4 and the current flowing through the inductor L1 change in a sine wave shape (see FIG. 2), but this sine wave shape change is also omitted in FIGS.

  In the half-period state P1, the first switching element Q1 is off, the second switching element Q2 is off, the third switching element Q3 is off, and the fourth switching element Q4 is on. The current path in the state P1 is shown in FIG. As shown in the figure, in the state P1, the current supplied from the AC power source E flows through the path of the capacitor C1, the inductor L1, the body diode D1 of the first switching element Q1, and the capacitor C3, thereby charging the capacitor C3. The

  In the state P2 created next to the state P1, the first switching element Q1 is on, the second switching element Q2 is off, the third switching element Q3 is off, and the fourth switching element Q4 is on. The current path in the state P2 is shown in FIG. As shown in the figure, in the state P2, the discharge current of the capacitor C3 flows through the path of the first switching element Q1 → the primary winding T1 of the transformer T → the fourth switching element Q4, and thereby the secondary winding of the transformer T. A voltage is induced on the lines T2a and T2b. The secondary side circuit 5 generates the output voltage Vout by rectifying and smoothing the induced voltage.

  In the state P3 created next to the state P2, the first switching element Q1 is off, the second switching element Q2 is off, the third switching element Q3 is off, and the fourth switching element Q4 is on. A current path in the state P3 is shown in FIG. As shown in the figure, in the state P3, the primary winding T1 → the fourth switching element Q4 → the second switching element Q2 is caused by the action of the primary winding T1 that keeps the current flowing in the same direction as the state P2. A current flows through the path of the body diode D2, and thereby a voltage is continuously induced in the secondary windings T2a and T2b of the transformer T.

  In the state P4 created next to the state P3, the first switching element Q1 is off, the second switching element Q2 is on, the third switching element Q3 is off, and the fourth switching element Q4 is off. A current path in the state P4 is shown in FIG. As shown in the figure, in the state P4, the current supplied from the AC power source E flows through the path of the body diode D4 of the capacitor C1, the inductor L1, the second switching element Q2, and the fourth switching element Q4.

  In the state P5 created next to the state P4, the first switching element Q1 is off, the second switching element Q2 is on, the third switching element Q3 is on, and the fourth switching element Q4 is off. A current path in the state P5 is shown in FIG. As shown in the figure, in the state P5, the discharge current of the capacitor C3 flows through the path of the third switching element Q3 → the primary winding T1 of the transformer T → the second switching element Q2, and thereby the secondary winding of the transformer T. A voltage having a polarity opposite to that of the states P2 and P3 is induced in the lines T2a and T2b.

  In the state P6 created next to the state P5, the first switching element Q1 is off, the second switching element Q2 is on, the third switching element Q3 is off, and the fourth switching element Q4 is off. A current path in the state P6 is shown in FIG. As shown in the figure, in the state P6, the primary winding T1 → second switching element Q2 → fourth switching element Q4 is affected by the action of the primary winding T1 that keeps the current flowing in the same direction as the state P5. A current flows through the path of the body diode D4, and thereby a voltage is continuously induced in the secondary windings T2a and T2b of the transformer T.

  In the state P7 created next to the state P6, the first switching element Q1 is off, the second switching element Q2 is on, the third switching element Q3 is off, and the fourth switching element Q4 is on. The current path in the state P7 is shown in FIG. As shown in the figure, in the state P7, as in the state P6, a current flows through the path of the primary winding T1 → the second switching element Q2 → the fourth switching element Q4 (body diode D4). Voltage is induced in the secondary windings T2a and T2b. Further, when the fourth switching element Q4 is turned on, the loss of the body diode D4 of the fourth switching element Q4 is eliminated.

  After the state P7, the state P1 is created again.

  In the negative half-period state N1, as in the positive half-period state P4, the first switching element Q1 is off, the second switching element Q2 is on, the third switching element Q3 is off, and the fourth switching element Q4 is off. . A current path in the state N1 is illustrated in FIG. As shown in the figure, in the state N1, the current supplied from the AC power source E flows through the path of the body diode D3 → the capacitor C3 of the third switching element Q3, thereby charging the capacitor C3.

  In the state N2 created next to the state N1, the first switching element Q1 is turned off, the second switching element Q2 is turned on, the third switching element Q3 is turned on, and the fourth switching element Q4 is turned off as in the half-period state P5. It has become. FIG. 8B shows a current path in the state N2. As shown in the figure, in the state N2, the discharge current of the capacitor C3 flows through the path of the third switching element Q3 → the primary winding T1 of the transformer T → the second switching element Q2, and thereby the secondary winding of the transformer T. A voltage is induced on the lines T2a and T2b. The secondary side circuit 5 generates the output voltage Vout by rectifying and smoothing the induced voltage.

  In the state N3 created next to the state N2, the first switching element Q1 is turned off, the second switching element Q2 is turned on, the third switching element Q3 is turned off, and the fourth switching element Q4 is turned off as in the half-period state P6. It has become. A current path in the state N3 is shown in FIG. As shown in the figure, in the state N3, the primary winding T1 → second switching element Q2 → fourth switching element Q4 is affected by the action of the primary winding T1 that keeps the current flowing in the same direction as the state N2. A current flows through the path of the body diode D4, and thereby a voltage is continuously induced in the secondary windings T2a and T2b of the transformer T.

  In the state N4 created next to the state N3, the first switching element Q1 is turned off, the second switching element Q2 is turned on, the third switching element Q3 is turned off, and the fourth switching element Q4 is turned on, as in the half-period state P7. It has become. FIG. 9A shows a current path in the state N4. As shown in the figure, in the state N4, similarly to the state N3, a current flows through the path of the primary winding T1 → the second switching element Q2 → the fourth switching element Q4 (body diode D4). Voltage is induced in the secondary windings T2a and T2b. Further, when the fourth switching element Q4 is turned on, the loss of the body diode D4 of the fourth switching element Q4 is eliminated, and the fourth switching element Q4 → second switching element Q2 → inductor L1 → capacitor C1 from the AC power source E. A current flows through the path, and energy is stored in the inductor L1.

  In the state N5 created next to the state N4, the first switching element Q1 is turned off, the second switching element Q2 is turned off, the third switching element Q3 is turned off, and the fourth switching element Q4 is turned on, as in the half-period state P1. It has become. FIG. 9B shows a current path in the state N5. As shown in the figure, in the state N5, the current supplied from the AC power source E flows through the path of the fourth switching element Q4 → the body diode D2 of the second switching element Q2 → the inductor L1 → the capacitor C1.

  In the state N6 created next to the state N5, the first switching element Q1 is turned on, the second switching element Q2 is turned off, the third switching element Q3 is turned off, and the fourth switching element Q4 is turned on, as in the half-period state P2. It has become. FIG. 9C shows a current path in the state N6. As shown in the figure, in the state N6, the discharge current of the capacitor C3 flows through the path of the first switching element Q1 → the primary winding T1 of the transformer T → the fourth switching element Q4, and thereby the secondary winding of the transformer T. A voltage having a polarity opposite to that of the states N2, N3, and N4 is induced in the lines T2a and T2b.

  In the state N7 created next to the state N6, the first switching element Q1 is turned off, the second switching element Q2 is turned off, the third switching element Q3 is turned off, and the fourth switching element Q4 is turned on, as in the half-period state P3. It has become. A current path in the state N7 is shown in FIG. As shown in the figure, in the state N7, the primary winding T1 → the fourth switching element Q4 → the second switching element Q2 is affected by the action of the primary winding T1 that keeps the current flowing in the same direction as the state N6. A current flows through the path of the body diode D2, and thereby a voltage is continuously induced in the secondary windings T2a and T2b of the transformer T.

  After state N7, state N1 is created again.

  As described above, the switching power supply device 1 performs an operation as a power factor correction circuit and an operation as a converter in both the positive and negative periods.

  According to the switching power supply 1 according to the present embodiment, since it is not necessary to provide a current feedback diode on the primary side, loss can be reduced and higher efficiency can be achieved than in the conventional switching power supply. Moreover, according to the switching power supply device 1, since the number of parts on the primary side excluding the AC power supply E and the control unit 6 is seven (Q1, Q2, Q3, Q4, C1, C3, L1), The switching power supply device (number of parts is 10) can be reduced in size.

  Although the embodiment of the switching power supply device 1 according to the present invention has been described above, the configuration of the present invention is not limited to the configuration of the embodiment. For example, the secondary side circuit 5 can rectify and smooth the voltage induced in the secondary winding of the transformer T (the number of secondary windings is not limited to two) to generate the output voltage Vout. As long as it can be changed to any circuit configuration. Examples of the secondary side circuit 5 include a full-wave rectification type secondary side circuit and a synchronous rectification type secondary side circuit.

DESCRIPTION OF SYMBOLS 1 Switching power supply device 2 1st series connection body 3 2nd series connection body 4 Full bridge circuit 5 Secondary side circuit 6 Control part 20 Load

Claims (2)

A first series connection body formed by connecting the first switching element and the second switching element in series via a first midpoint;
A second series connection body formed by connecting a third switching element and a fourth switching element in series via a second middle point, connected in parallel to the first series connection body;
A power factor improving capacitor connected in parallel to the first and second series-connected bodies;
A transformer having a primary winding connected between the first and second midpoints;
A secondary side circuit for rectifying and smoothing a voltage induced in the secondary winding of the transformer;
An inductor having one end connected to the first midpoint;
A capacitor having one end connected to the other end of the inductor;
A controller for controlling the first, second, third and fourth switching elements;
With
An AC power supply can be connected between the other end of the capacitor and the second middle point,
The controller is
a) a first control for turning on / off the first switching element while turning off the second and third switching elements and turning on the fourth switching element;
b) a second control for turning on / off the third switching element while turning off the first and fourth switching elements and turning on the second switching element;
c) third control for turning off the first and third switching elements and turning on the second and fourth switching elements;
The switching power supply device is characterized in that it is repeatedly executed.   2. The switching power supply device according to claim 1, wherein the first, second, third and fourth switching elements are MOSFETs including a body diode.

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