JP2006262683A - Switching power supply and control circuit - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a switching power supply, having a simple constitution and preventing a magnetic deflection in a transformer, without installing dummy resistors. <P>SOLUTION: The switching power supply is provided with switches 3-1, 3-2 in between a pulse sorting circuit 37 and drive circuits 38, 39, and switches 4-1, 4-2 between the drive circuits 38, 39 and the switching elements 32-35. It is so constituted that a drive pulse inputted to the switching elements 32, 35 and is such that the drive pulse inputted sequentially to the switching elements 33, 34 become same as the drive pulse that is outputted from the same drive circuit. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a switching power supply device that boosts or lowers the power of a DC power supply using a switching element, a transformer, and the like, and supplies the power to a load, and particularly relates to drive control of the switching power supply device when output power is close to zero.

FIG. 2A shows an existing switching power supply device.
A switching power supply 20 shown in FIG. 2A is a transformer-insulated full-bridge PWM (Pulse Width Modulation) switching power supply, and includes a DC power supply 21 and a conversion for converting DC power of the DC power supply 21 into AC power. A circuit 22; a transformer 23 that steps up or down the AC power converted by the conversion circuit 22; a rectifier circuit 28 that includes diodes 24-27 and rectifies the output of the transformer 23; and a load that smoothes the output of the rectifier circuit 28 29 includes a coil 30 serving as a smoothing circuit to be supplied to 29 and a control circuit 31 for controlling the driving of the conversion circuit 22.

  The conversion circuit 22 includes switching elements 32 to 35 which are MOSFETs (Metal Oxide Semiconductor Field Effect Transistors). That is, the high potential side of the DC power supply 21 and the switching element 32 are connected, the low potential side of the DC power supply 21 and the switching element 33 are connected, the switching elements 32 and 33 are connected in series, and the switching element 32 and The midpoint of 33 is connected to one terminal of the primary side coil of the transformer 23. Further, the high potential side of the DC power supply 21 and the switching element 34 are connected, the low potential side of the DC power supply 21 and the switching element 35 are connected, the switching elements 34 and 35 are connected in series, and the switching element 34 and The midpoint of 35 is connected to the other terminal of the primary side coil of the transformer 23.

  The control circuit 31 includes a pulse output circuit 36 that outputs a pulse signal S1 based on a comparison result between a triangular wave and a command value, a pulse distribution circuit 37 that distributes each pulse of the pulse signal S1 and outputs pulse signals S2 and S3, A drive circuit 38 that outputs a drive pulse signal S4 that turns on and off the switching elements 32 and 35 based on the pulse signal S2, and a drive pulse signal S5 that turns on and off the switching elements 33 and 34 based on the pulse signal S3 are output. And a drive circuit 39 that performs the above operation.

FIG. 2B shows the pulse signals S1 to S3 and the drive pulse signals S4 and S5.
In the example shown in FIG. 2B, the pulse signal S1 is generated so as to be at a high level when the command value is smaller than the triangular wave and at a low level when the command value is larger than the triangular wave. In addition, the pulse signal S2 is generated by an even-numbered pulse among consecutive pulses of the pulse signal S1. The pulse signal S3 is generated by an odd-numbered pulse among consecutive pulses of the pulse signal S1.

  The drive pulse signal S4 generated based on the pulse signal S2 is input to the switching elements 32 and 35, and the drive pulse signal S5 generated based on the pulse signal S3 is input to the switching elements 33 and 34. The switching elements 32 and 35 and the switching elements 33 and 35 are alternately turned on and off.

  By the way, when the output power of the switching power supply 20 is close to zero, for example, when the power required from the load 29 is small, the characteristics of the components used in the drive circuits 38 and 39 (mainly the transistor current amplification factor and MOSFET) are used. There may be a difference between the minimum pulse widths output from the drive circuits 38 and 39, respectively, due to variations in the ON threshold value).

FIG. 2C is a diagram illustrating the pulse signals S1 to S3 and the drive pulse signals S4 and S5 when the output power of the switching power supply device 20 is close to zero.
As shown in FIG. 2C, when the output power of the switching power supply device 20 is close to zero, the pulse width of the drive pulse signal S4 varies depending on the component characteristics of the drive circuits 38 and 39. It is narrower than the pulse width. For this reason, the pulse width of the drive pulse signal S4 becomes too narrow, and a difference occurs between the on period of the switching elements 32 and 35 and the on period of the switching elements 33 and 34, and the transformer 23 may be demagnetized.

Therefore, for example, the drive pulse signal S4 or the drive S5 is adjusted so that the transformer 23 is not demagnetized (see, for example, Patent Document 1 and Patent Document 2).
However, no consideration is given to the demagnetization due to variations in component characteristics when the output power is close to zero. Further, in the case where the drive pulse signal S4 or S5 is adjusted so that the transformer 23 is not demagnetized, the adjustment of the drive pulse signal S4 or S5 is complicated, so that the configuration of the control circuit 31 is also complicated. There is.

  Therefore, in order to prevent the transformer 23 from being demagnetized with a simple configuration, for example, it is conceivable to provide a dummy resistor 40 between the coil 30 and the load 29 as shown by a broken line in FIG. .

Thereby, even when the output power of the switching power supply device 20 is close to zero, each pulse of the drive pulse signals S4 and S5 can have a certain width, so that the bias of the transformer 23 can be prevented.
JP 2001-258250 (Pages 3-6, FIGS. 1-7) JP 2003-88113 (Pages 2-6, FIGS. 1-11)

However, if the dummy resistor 40 is provided between the coil 30 and the load 29, there is a problem that the loss increases correspondingly and the power supply efficiency decreases.
SUMMARY OF THE INVENTION An object of the present invention is to provide a switching power supply device and a control circuit that have a simple configuration and can prevent the bias of a transformer without providing a dummy resistor.

In order to solve the above problems, the present invention adopts the following configuration.
That is, the switching power supply device of the present invention includes a conversion circuit in which the first and second switching elements are alternately turned on and off based on pulses continuously input at a predetermined frequency to convert DC power into AC power; A transformer for stepping up or stepping down AC power converted by the conversion circuit, a rectifier circuit for rectifying the output of the transformer, a smoothing circuit for smoothing the output of the rectifier circuit, and the first pulse based on an input pulse. The first and second drive circuits that output drive pulses for driving the second switching element, the pulse output circuit that outputs pulses at the predetermined frequency, and the pulse output circuit continuously output the pulses. A pulse distribution circuit that distributes the pulse into a first pulse and a second pulse; and the first and second pulses distributed by the pulse distribution circuit After being continuously output to one of the first and second drive circuits, the first and second pulses distributed by the pulse distribution circuit are then transmitted to the first and second drive circuits. A first switch that switches to the other one of the first and second driving circuits, and the first and second pulses that are continuously output to one of the first and second drive circuits. After drive pulses continuously output from one of the first and second drive circuits are alternately output to the first and second switching elements, respectively, the first and second drive circuits Drive pulses continuously output from the other of the first and second drive circuits based on the first and second pulses output continuously to the other one of the first and second pulses, respectively. To be output alternately to the switching element Characterized in that it comprises a second switch for switching, and a switching control circuit for controlling the respective switching operations of the first and second switches.

  In this way, the drive pulse input to the first switching element and the drive pulse input to the second switching element are configured to be the drive pulse output from the same drive circuit. There is no deviation in the width of the drive pulse that is alternately input to the first and second switching elements. Thereby, it can prevent that a transformer demagnetizes. In addition, it is possible to prevent the biasing of the transformer without providing a dummy resistor with a simple configuration in which the existing switching power supply device includes only the first and second switches and the switching control circuit.

  Further, the switching power supply device of the present invention includes a conversion circuit in which the first and second switching elements are alternately turned on and off based on pulses continuously input at a predetermined frequency to convert DC power into AC power; A transformer for stepping up or stepping down the AC power converted by the conversion circuit, a rectifier circuit for rectifying the output of the transformer, a smoothing circuit for smoothing the output of the rectifier circuit, and the first pulse based on an input pulse. The first and second drive circuits for outputting drive pulses for driving the second switching element, the pulse output circuit for outputting pulses at the predetermined frequency, and the pulse output circuit for continuous output. After the first and second pulses are continuously output to the first drive circuit, the first and second pulses continuously output from the pulse output circuit are A first switch for switching to be continuously output to the second drive circuit, and the first drive based on the first and second pulses continuously output to the first drive circuit. The drive pulses continuously output from the circuit are alternately output to the first and second switching elements, respectively, and then the first and second pulses are continuously output to the second drive circuit. And a second switch for switching so that the driving pulses continuously output from the second driving circuit are alternately output to the first and second switching elements, respectively. And a switching control circuit for controlling each switching operation of the two switches.

Thereby, compared with the switching power supply device of the present invention, the circuit scale can be reduced by eliminating the pulse distribution circuit.
The switching control circuit may be configured to switch the first and second switches at an even multiple of the predetermined frequency.

Accordingly, the first and second switches can be switched at an arbitrary timing, so that the degree of freedom in circuit design can be improved.
Further, the switching power supply device of the present invention includes a conversion circuit in which the first and second switching elements are alternately turned on and off based on pulses continuously input at a predetermined frequency to convert DC power into AC power; A transformer for stepping up or stepping down the AC power converted by the conversion circuit, a rectifier circuit for rectifying the output of the transformer, a smoothing circuit for smoothing the output of the rectifier circuit, and the first pulse based on an input pulse. First and second drive circuits that output drive pulses for driving the second switching elements, a pulse output circuit that outputs pulses at the predetermined frequency, a drive pulse changeover switch, and the drive pulse changeover switch A switching control circuit for controlling the driving pulse, wherein the driving pulse selector switch receives at least a driving pulse output from the first driving circuit. The connection state for outputting to the switching element and the connection state for outputting to the second switching element and the connection state for outputting the drive pulse output from the second drive circuit to the second switching element and the first switching are switched. The switching control circuit switches to a connection state that outputs to the element, and the switching control circuit includes a period during which the first switching element is turned on by the drive pulse output from the first drive circuit within a period that is an even multiple of the cycle of the predetermined frequency. The switching elements of the two switching elements are made equal to each other, and the period in which the first switching elements are turned on and the period in which the second switching elements are turned on by the drive pulse output from the second driving circuit are made equal. The drive pulse selector switch is controlled.

  In this case, the ON period of the drive pulse input to the first switching element by the first drive circuit is the same as the ON period of the drive pulse input to the second switching element, and the second drive circuit Since the ON period of the drive pulse input to the first switching element is controlled to be the same as the ON period of the drive pulse input to the second switching element, the transformer is prevented from being demagnetized. be able to.

  The present invention can also be understood as a control circuit for a power conversion circuit in which the first and second switching elements are alternately turned on and off to transmit AC power to the transformer.

  According to the present invention, it is possible to prevent biasing of the transformer without providing a dummy resistor with a simple configuration.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 1A is a diagram illustrating a switching power supply device according to an embodiment of the present invention. In FIG. 1A, the same components as those shown in FIG.

  A switching power supply device 1 shown in FIG. 1A includes a DC power supply 21, a conversion circuit 22, a transformer 23, a rectifier circuit 28, a coil 30 as a smoothing circuit, and a control circuit 2. Yes.

  The control circuit 2 alternately distributes a pulse output circuit 36 that outputs a pulse signal S1 based on an input command value and a triangular wave, and a continuous pulse of the pulse signal S1 output from the pulse output circuit 36 to generate a pulse signal. A pulse distribution circuit 37 that outputs S2 and a pulse signal S3; a drive circuit 38 (first drive circuit) that outputs a pulse signal S4; a drive circuit 39 (second drive circuit) that outputs a pulse signal S5; Switches 3-1 and 3-2 (first switch) provided between the pulse distribution circuit 37 and the drive circuits 38 and 39, and switches provided between the drive circuits 38 and 39 and the switching elements 32-35. 4-1 and 4-2 (second switch, drive pulse changeover switch) and respective switching operations of the switches 3-1, 3-2, 4-1, and 4-2. It is constituted by a switching control circuit 5 for outputting a switching signal SW1 for Gosuru.

  The switching elements 32 to 35 are not limited to MOSFETs such as IGBTs (Insulated Gate Bipolar Transistors). The switching elements 32 and 35 correspond to the first switching element in the claims. The switching elements 33 and 34 correspond to the second switching element in the claims. Further, the switches 3-1 and 3-2 and the switches 4-1 and 4-2 are interlocked with each other, and are synchronized with a double period of a triangular wave used when generating the pulse signal S1. To do. Further, the switching control circuit 5 may be constituted by, for example, a counter or a flip-flop.

  One terminal of the switch 3-1 is always connected to the terminal that outputs the pulse signal S2 of the pulse distribution circuit 37, and the other terminal is connected to the drive circuit 38 or 39 based on the switching signal SW1. One terminal of the switch 3-2 is always connected to the terminal that outputs the pulse signal S3 of the pulse distribution circuit 37, and the other terminal is connected to the drive circuit 38 or 39 based on the switching signal SW1. . That is, when the switch 3-1 is connected to the drive circuit 38, the switch 3-2 is connected to the drive circuit 39, and when the switch 3-1 is connected to the drive circuit 39, the switch 3-2 is driven. The circuit 38 is connected.

  One terminal of the switch 4-1 is always connected to the drive circuit 38, and the other terminal is connected to the gate terminals of the switching elements 32 and 35 or the switching elements 33 and 34 based on the switching signal SW1. Connected to each gate terminal. In addition, one terminal of the switch 4-2 is always connected to the drive circuit 39, and the other terminal is based on the switching signal SW1, and the gate terminals of the switching elements 32 and 35 or the switching elements 33 and 34, respectively. Is connected to the gate terminal. That is, when the switch 4-1 is connected to the respective gate terminals of the switching elements 32 and 35, the switch 4-2 is connected to the respective gate terminals of the switching elements 33 and 34, and the switch 4-1 is switched to the switching element. When connected to the respective gate terminals of 33 and 34, the switch 4-2 is connected to the respective gate terminals of the switching elements 32 and 35.

  FIG. 1B is a diagram illustrating the pulse signals S1 to S3 and the drive pulse signals S4 and S5 when the output power of the switching power supply device 1 is close to zero. 1B shows the drive pulse signal input to the gate terminals of the switching elements 32 and 35, and the second stage input to the gate terminals of the switching elements 33 and 34. The drive pulse signal is shown.

  In the example shown in FIG. 1B, drive pulses having the same width are input to the gate terminals of the switching elements 32 and 35, and drive pulses having the same width are also input to the gate terminals of the switching elements 33 and 34. Although shown as being input, in practice, the source voltage of the switching element 32 and the source voltage of the switching element 33 are different, and the source voltage of the switching element 34 and the source voltage of the switching element 35 are different. Therefore, the potential applied to the gate terminal of the switching element 32 and the potential applied to the gate terminal of the switching element 33 are different, and the potential applied to the gate terminal of the switching element 34 and the gate terminal of the switching element 35 are applied. The level shift is performed in the drive pulses input to the respective gate terminals of the switching elements 32 and 35 so that the potential is different from the potential to be applied, and the level is also detected in the drive pulses input to the respective gate terminals of the switching elements 33 and 34. A shift is performed.

  First, of the continuous pulses (S1-1 to S1-4) of the pulse signal S1 output from the pulse output circuit 36, the first pulse S1-1 (first pulse) is pulsed by the pulse distribution circuit 37. When being distributed as the first pulse of the signal S3, the switch 3-1 is connected to the drive circuit 38, and the switch 3-2 is connected to the drive circuit 39 (the switches 3-1 and 3-2 are “ left"). The switch 4-1 is connected to the gate terminals of the switching elements 32 and 35, and the switch 4-2 is connected to the gate terminals of the switching elements 33 and 34 (switches 4-1 and 4- 2 is “left”). Therefore, the first pulse of the pulse signal S3 is output to the drive circuit 39 via the switch 3-2. The drive circuit 39 outputs the first pulse of the drive pulse signal S5 based on the first pulse of the pulse signal S3. Then, the first pulse of the drive pulse signal S5 output from the drive circuit 39 is output to the respective gate terminals of the switching elements 33 and 34 via the switch 4-2.

  Next, when the second pulse S1-2 (second pulse) of the pulse signal S1 is distributed as the first pulse of the pulse signal S2 by the pulse distribution circuit 37, the switch 3-1 is connected to the drive circuit 39. In addition to being connected, the switch 3-2 is connected to the drive circuit 38 (the switches 3-1 and 3-2 are “right”). The switch 4-1 is connected to the gate terminals of the switching elements 33 and 34, and the switch 4-2 is connected to the gate terminals of the switching elements 32 and 35 (switches 4-1 and 4- 2 is “right”). Therefore, the first pulse of the pulse signal S2 is output to the drive circuit 39 via the switch 3-1. The drive circuit 39 outputs the second pulse of the drive pulse signal S5 based on the first pulse of the pulse signal S2. The second pulse of the drive pulse signal S5 output from the drive circuit 39 is output to the respective gate terminals of the switching elements 32 and 35 via the switch 4-2.

  Next, when the third pulse S1-3 (first pulse) of the pulse signal S1 is distributed as the second pulse of the pulse signal S3 by the pulse distribution circuit 37, the switch 3-1 is connected to the drive circuit 39. In addition to being connected, the switch 3-2 is connected to the drive circuit 38 (the switches 3-1 and 3-2 are “right”). The switch 4-1 is connected to the gate terminals of the switching elements 33 and 34, and the switch 4-2 is connected to the gate terminals of the switching elements 32 and 35 (switches 4-1 and 4- 2 is “right”). Therefore, the second pulse of the pulse signal S3 is output to the drive circuit 38 via the switch 3-2. The drive circuit 38 outputs the first pulse of the drive pulse signal S4 based on the second pulse of the pulse signal S3. Then, the first pulse of the drive pulse signal S4 output from the drive circuit 38 is output to the respective gate terminals of the switching elements 33 and 34 via the switch 4-1.

  When the fourth pulse S1-4 (second pulse) of the pulse signal S1 is distributed as the second pulse of the pulse signal S2 by the pulse distribution circuit 37, the switch 3-1 is connected to the drive circuit 38. At the same time, the switch 3-2 is connected to the drive circuit 39 (the switches 3-1 and 3-2 are “left”). The switch 4-1 is connected to the gate terminals of the switching elements 32 and 35, and the switch 4-2 is connected to the gate terminals of the switching elements 33 and 34 (switches 4-1 and 4- 2 is “left”). Therefore, the second pulse of the pulse signal S2 is output to the drive circuit 38 via the switch 3-1. The drive circuit 38 outputs the second pulse of the drive pulse signal S4 based on the second pulse of the pulse signal S2. The second pulse of the drive pulse signal S4 output from the drive circuit 38 is output to the respective gate terminals of the switching elements 32 and 35 via the switch 4-1.

  As described above, since the switching operations of the switches 3-1, 3-2, 4-1, and 4-2 are controlled, the drive pulse input to the switching elements 32 and 35 and the switching element 33 are then input. And the drive pulse input to 34 can be the drive pulse output from the same drive circuit. For this reason, the drive pulse width input to the switching elements 32 and 35 and the drive pulse width input to the switching elements 33 and 34 next can be made substantially the same. It is possible to eliminate the deviation between the drive pulse width and the width of the drive pulse input to the switching elements 33 and 34 next.

  In other words, the switching operation of each of the switches 4-1 and 4-2 is performed according to the ON period of the driving pulse input to the switching elements 32 and 35 by the driving circuit 38 and the driving pulse input to the switching elements 33 and 34. And the ON period of the drive pulse input to the switching elements 32 and 35 by the drive circuit 39 and the ON period of the drive pulse input to the switching elements 33 and 34 are controlled to be the same. Therefore, the deviation between the drive pulse width input to the switching elements 32 and 35 and the width of the drive pulse input to the switching elements 33 and 34 can be eliminated.

  As a result, there are variations in the component characteristics used in the drive circuits 38 and 39, respectively, and the switching elements 32 and 35 are turned on and off even when the output power of the switching power supply device 1 is close to zero. When the switching elements 32 and 35 are turned on and off and the switching elements 32 and 35 are not turned on and off, the switching elements 33 and 34 can be prevented from being turned on and off. it can. Further, the existing switching power supply device 20 is simply configured to include the switches 3-1 and 3-2, the switches 4-1 and 4-2, and the switching control circuit 5. Biasing can be prevented.

  In the above embodiment, the output destination of each pulse of the pulse signal S2 output from the pulse distribution circuit 37 is switched to the drive circuit 38 or 39 by the switch 3-1, and the pulse signal S3 output from the pulse distribution circuit 37 is switched. Although the output destination of each pulse is switched to the drive circuit 38 or 39 by the switch 3-2, the pulse distribution circuit 37 is eliminated and a new switch is provided between the pulse output circuit 36 and the drive circuits 38 and 39. The output destination of each pulse of the pulse signal S1 may be switched to the drive circuit 38 or 39 by the switch. The new switch provided between the pulse output circuit 36 and the drive circuits 38 and 39 corresponds to the first switch in the claims, and the switching operation is controlled by the switching signal SW1. . As a result, the circuit scale of the switching power supply device 1 can be reduced by eliminating the pulse distribution circuit 37.

  In the above embodiment, the switches 3-1, 3-2, 4-1, and 4-2 are configured to perform switching operations in synchronization with the double period of the triangular wave. 2, 4-1, and 4-2 may be configured to perform switching operation in synchronization with any even-numbered period of the triangular wave (2 times period, 4 times period, 6 times period,...). . That is, in this embodiment, the switching operation is performed so that the drive pulse width is not biased every two cycles. However, if there is no problem in the operation of the transformer 23, the drive pulse width is biased every arbitrary even multiple cycle. The switching operation may be performed so that there is no more. As a result, the switches 3-1, 3-2, 4-1, and 4-2 can be switched at an arbitrary timing, so that the degree of freedom in circuit design can be improved.

  Moreover, in the said embodiment, although the conversion circuit 22 is comprised by forming the full bridge converter using the switching elements 32-35, it is a half bridge using the switching elements 32 and 33 and two capacitors. The conversion circuit 22 may be configured by forming a converter. That is, the conversion circuit 22 may be configured by replacing the switching elements 34 and 35 with capacitors. At this time, the switching element 32 corresponds to the first switching element in the claims, and the switching element 33 corresponds to the second switching element in the claims. The output destination of each pulse of the drive pulse signal S4 is switched to the switching element 32 or 33 by the switch 4-1, and the output destination of each pulse of the drive pulse signal S5 is switched to the switching element 32 or 33 by the switch 4-2. Can be switched to.

  In the above embodiment, the rectifier circuit 28 is configured using the diodes 24 to 27. For example, the rectifier circuit 28 is configured using a switching element such as a MOSFET. There is no particular limitation.

  Moreover, in the said embodiment, although the smoothing circuit is comprised using the coil 30, the form of a smoothing circuit is not specifically limited, for example, comprises a smoothing circuit using a capacitor | condenser other than the coil 30, for example.

It is a figure which shows the switching power supply device of embodiment of this invention. It is a figure which shows the existing switching power supply device.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Switching power supply device 2 Control circuit 3-1, 3-2 Switch 4-1, 4-2 switch 5 Switching control circuit 20 Switching power supply device 21 DC power supply 22 Converter circuit 23 Trans | transformer 24-27 Diode 28 Rectifier circuit 29 Load 30 Coil 31 Control Circuits 32-35 Switching Element 36 Pulse Output Circuit 37 Pulse Distribution Circuit 38, 39 Drive Circuit 40 Dummy Resistor

Claims (5)

A conversion circuit in which the first and second switching elements are alternately turned on and off based on pulses continuously input at a predetermined frequency to convert DC power into AC power;
A transformer for stepping up or stepping down AC power converted by the conversion circuit;
A rectifier circuit for rectifying the output of the transformer;
A smoothing circuit for smoothing the output of the rectifier circuit;
First and second drive circuits for outputting drive pulses for driving the first and second switching elements based on input pulses;
A pulse output circuit for outputting pulses at the predetermined frequency;
A pulse distribution circuit that distributes the pulses continuously output from the pulse output circuit into a first pulse and a second pulse;
The first and second pulses distributed by the pulse distribution circuit are continuously output to one of the first and second drive circuits, and then distributed by the pulse distribution circuit. A first switch that switches so that the first and second pulses are continuously output to the other of the first and second drive circuits;
Based on first and second pulses continuously output to one of the first and second drive circuits, continuously output from one of the first and second drive circuits. Based on the first and second pulses continuously output to the other of the first and second drive circuits after the drive pulses are alternately output to the first and second switching elements, respectively. A second switch for switching so that a drive pulse continuously output from the other of the first and second drive circuits is alternately output to the first and second switching elements, respectively.
A switching control circuit for controlling the switching operation of each of the first and second switches;
A switching power supply device comprising: A conversion circuit in which the first and second switching elements are alternately turned on and off based on pulses continuously input at a predetermined frequency to convert DC power into AC power;
A transformer for stepping up or stepping down AC power converted by the conversion circuit;
A rectifier circuit for rectifying the output of the transformer;
A smoothing circuit for smoothing the output of the rectifier circuit;
First and second drive circuits for outputting drive pulses for driving the first and second switching elements based on input pulses;
A pulse output circuit for outputting pulses at the predetermined frequency;
After the first and second pulses continuously output from the pulse output circuit are continuously output to the first drive circuit, the first pulse output from the pulse output circuit is then output. And a first switch for switching so that a second pulse is continuously output to the second drive circuit;
Drive pulses continuously output from the first drive circuit based on the first and second pulses continuously output to the first drive circuit are respectively supplied to the first and second switching elements. After being alternately output, the drive pulses continuously output from the second drive circuit based on the first and second pulses continuously output to the second drive circuit are respectively output from the second drive circuit. A second switch for switching so as to be alternately output to the first and second switching elements;
A switching control circuit for controlling the switching operation of each of the first and second switches;
A switching power supply device comprising: The switching power supply device according to claim 1 or 2,
The switching control circuit switches the first and second switches at an even multiple of the predetermined frequency,
The switching power supply device characterized by the above-mentioned. A conversion circuit in which the first and second switching elements are alternately turned on and off based on pulses continuously input at a predetermined frequency to convert DC power into AC power;
A transformer for stepping up or stepping down AC power converted by the conversion circuit;
A rectifier circuit for rectifying the output of the transformer;
A smoothing circuit for smoothing the output of the rectifier circuit;
First and second drive circuits for outputting drive pulses for driving the first and second switching elements based on input pulses;
A pulse output circuit for outputting pulses at the predetermined frequency;
A drive pulse selector switch;
Comprising a switching control circuit for controlling the drive pulse selector switch;
The drive pulse changeover switch switches between a connection state in which at least a drive pulse output from the first drive circuit is output to the first switching element and a connection state in which the drive pulse is output to the second switching element. Switching between a connection state in which the drive pulse output from the drive circuit is output to the second switching element and a connection state in which the drive pulse is output to the first switching element;
The switching control circuit includes a period in which the first switching element is turned on and a period in which the second switching element is turned on by the drive pulse output from the first drive circuit within a period that is an even multiple of the cycle of the predetermined frequency. And controlling the drive pulse changeover switch so that the period when the first switching element is turned on and the period when the second switching element is turned on are equalized by the drive pulse output from the second drive circuit. A switching power supply device. A control circuit of a power conversion circuit in which first and second switching elements are alternately turned on and off to transmit AC power to a transformer;
First and second drive circuits for outputting drive pulses for driving the first and second switching elements based on input pulses;
A pulse output circuit for outputting pulses at the predetermined frequency;
A drive pulse selector switch;
Comprising a switching control circuit for controlling the drive pulse selector switch;
The drive pulse changeover switch switches between a connection state in which at least a drive pulse output from the first drive circuit is output to the first switching element and a connection state in which the drive pulse is output to the second switching element. Switching between a connection state in which the drive pulse output from the drive circuit is output to the second switching element and a connection state in which the drive pulse is output to the first switching element;
The switching control circuit includes a period in which the first switching element is turned on and a period in which the second switching element is turned on by the drive pulse output from the first drive circuit within a period that is an even multiple of the cycle of the predetermined frequency. And controlling the drive pulse changeover switch so that the period when the first switching element is turned on and the period when the second switching element is turned on are equalized by the drive pulse output from the second drive circuit. A control circuit for a power conversion circuit.

Images