JP2005073454A - Power supply circuit - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To output a step-up voltage and an inversion step-up voltage, by making a choke coil perform chopping operation. <P>SOLUTION: A first switching element 4, a choke coil 5, and a second switching element 6 are connected in series between a power supply terminal 3 and a grounding point. At the time of a step-up start when the second switching element 6 starts the chopping operation, the chopping operation of the first switching element 4 is stopped for a fixed period of time. Also, at the time of an inversion step-up start when the first switching element 4 starts the chopping operation, the chopping operation of the second switching element 6 is stopped for a fixed period of time. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a power supply circuit that requires a multi-output power supply.

  As a conventional power supply circuit, the thing of the structure described in patent document 1, 2 can be illustrated.

  An example of a conventional power supply circuit will be described with reference to FIGS.

  FIG. 3 is a circuit configuration diagram of a conventional power supply circuit, in which 1 and 2 are control circuits, 3 is a power supply terminal, 4 and 6 are switch elements, 5 is a choke coil, 7 and 8 are rectifier diodes, and 9 and 10 are A smoothing capacitor, 11 is an inverted boost output terminal, 12 is a boost output terminal, 13 is an inverted boost output feedback terminal, and 14 is a boost output feedback terminal.

  In the power supply circuit having the above configuration, the boosting operation and the inverting boosting operation are realized by the switch elements 4 and 6 provided at both ends of the choke coil 5. Loads are connected to the terminals 11 and 12, respectively.

  When the load power is the same, the number of times that the switch of the boosting operation and the inverting boosting operation operates within a certain period may be the same. For example, when switching alternately every time or every several times You may switch to

  If the load power is not equal, the number of switches with the larger load power is increased.

  The switch elements 4 and 6 are connected to both ends of the choke coil 5 and cause a current to flow between the power supply terminal 3 and the ground by performing a switch operation.

  FIG. 4 is a timing chart in each part of the circuit of FIG. 3, e in FIG. 4 is a waveform diagram showing the on / off timing of the switch element 4, and the output waveform is shown in g. f is a waveform diagram showing the on / off timing of the switch element 6, and its output waveform is shown in h.

  When the switch element 4 and the switch element 6 are simultaneously turned on, the choke coil 5 is charged with power, and then the switch element 4 is turned off, so that a reverse electromotive force for inverting boosting is generated at the output of the switch element 4 To do. On the other hand, when the switch element 6 is turned off, a boosting back electromotive force is generated at the output of the switch element 6. Thus, if the load power is the same, an inverted boost output and a boost output can be obtained simultaneously with one choke coil 5 by alternately performing the boost operation and the inverting boost operation.

  In FIG. 3, the rectifier diodes 7 and 8 rectify the current flowing through the choke coil 5, and the control circuits 1 and 2 control the on / off operation of the switch elements 4 and 6.

  During the boosting operation, the switch element 6 is turned on for a predetermined time with the switch element 4 turned on, the choke coil 5 is turned on, and then the diode 8 is energized by the back electromotive force generated by turning off the switch element 6. Then, the capacitor 10 is charged. On the other hand, at the time of inverting boosting, the switch element 4 is turned on for a predetermined time with the switch element 6 turned on, the choke coil 5 is turned on, and then the diode 7 is turned on by the back electromotive force generated by turning off the switch element 4. Energize to charge the capacitor 9. Thus, a negative voltage is obtained at the terminal 11 and a positive voltage is obtained at the terminal 12.

  The boosting and inverting boosting obtained as described above are fed back to the control circuits 1 and 2 by the feedback terminal 13 and the feedback terminal 14 to form a loop for controlling the ON period of the switch element 4 and the switch element 6. The inversion boosting is controlled to a predetermined voltage.

By alternately operating the boosting operation and the inverting boosting operation every predetermined cycle, it is possible to simultaneously generate a positive voltage and a negative voltage with one choke coil 5.
JP 2002-354822 A JP 2002-262548 A

  However, in the conventional configuration shown in FIG. 3, since the boosting operation and the inverting boosting operation are alternately performed at a predetermined cycle, the time required for the boosted voltage at the terminal 12 to reach the predetermined voltage Vj (hereinafter referred to as start-up time). (referred to as t5) and the time required for the inverted boosted voltage at the terminal 11 to reach the predetermined voltage Vk (hereinafter referred to as start-up time t6) do not necessarily match. Depending on the difference in load power, t5> t6, or conversely, t5 <t6. FIG. 5 shows the boosting time.

  For this reason, when the voltage application order is defined in the load, the application order may be reversed due to fluctuations in the load power, so it is necessary to limit the startup time.

  Also, when boosting and inverting boosting are started simultaneously, the inrush current on the boosting side affects the inversion boosting period due to the inrush current flowing through the choke coil 5, or conversely, the inrush current of the inversion boosting becomes the boost feedback. There are problems such as causing an over-boosting phenomenon.

  An object of the present invention is to provide a power supply circuit that solves the above-described conventional problems and has stable start-up characteristics without reversing the start-up time between boosting and inverting boosting.

  In order to achieve the above object, the present invention has a configuration in which a time difference is given in advance between the boosting operation and the inverting boosting operation, and the startup time of the boosting output and the inverting boosting is not reversed. A stable boosting operation is possible, and even if the load power fluctuates, it is possible to realize boosting or inverting boosting in which the application order of the boosting voltage and the inverting boosting is not reversed.

  According to the present invention, in a multi-output power supply circuit that realizes boosting and inverting boosting using a single choke coil, one of the boosting output or the inverting boosting output can be activated with a delay of a predetermined time. It is possible to provide a power supply circuit having stable start-up characteristics without reversing the start-up time between boosting and inverting boosting caused by fluctuations or load power differences.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

  FIG. 1 is a circuit configuration diagram of a power supply circuit according to an embodiment of the present invention, and FIG. 2 is a waveform diagram of an output voltage when the power supply circuit according to the present embodiment is started.

  In FIG. 1, 1 is a first control circuit, 2 is a second control circuit, 3 is a power supply terminal, 4 is a first switch element, 5 is a choke coil, 6 is a second switch element, and 7 and 8 are Rectifier diodes 9, 10 are smoothing capacitors, 11 is an inverted boost output terminal, 12 is a boost output terminal, 13 is an inverted boost output feedback terminal, 14 is a boost output feedback terminal, and 15 is a third control circuit. is there.

  In the present embodiment, the first control circuit 1 controls on / off of the first switch element 4. At the time of inverting boosting, the second switch circuit 6 is turned on by the second control circuit 2, and the first switch element 4 is also turned on for a predetermined time. When a current is passed through the choke coil 5 during this ON period and then only the first switch element 4 is turned off while the second switch element 6 is turned on, the current flowing through the choke coil 5 causes the terminal to pass through the rectifier diode 7. 11, an inverted boosted voltage is generated. By assuming the inversion boost start-up time t3 in consideration of the maximum value and the minimum value of the load, the boost operation is started this time after a preset time t4 after the inversion boost reaches the predetermined voltage Vd. At this time, the boosting operation and the inverting boosting operation are alternately repeated at a preset cycle.

  C and d in FIG. 2 show the start-up timing of the inversion boosting and boosting. c is a boost output, and d is an inverted boost output. In this way, by controlling the ON period of the first switch element 4 and the second switch element 6, it is possible to obtain a boost and an inverting boost with a time difference at the time of start-up by one choke coil 5. .

  Similarly, the first switch element 4 is turned on by the first control circuit 1, and the second switch element 6 is also turned on for a predetermined time. In the same manner as described above, when a current is passed through the choke coil 5 during this ON period and then only the second switch element 6 is turned off with the first switch element 4 turned on, the current flowing through the choke coil 5 causes the rectifier diode 8 to flow. As a result, a boosted voltage is generated at the terminal 12. As described above, assuming the boost start time t1 in consideration of the maximum value and the minimum value of the boost output load, this time, after the boost output reaches the predetermined voltage Va, this time, after the preset time t2, the inversion is reversed. Start boosting operation. At this time, the inverting step-up operation and the step-up operation are repeated alternately in a preset cycle.

  2A and 2B show inversion boosting and boosting start timing. a is a boost output and b is an inverted boost output. In this way, by controlling the ON period of the first switch element 4 and the second switch element 6 in reverse, the time difference at the start-up of the boosting and the inverting boosting can be reversed.

  The first control circuit 1 and the second control circuit 2 are controlled at the time t2 or the time t4 by the third control circuit 15 that controls the time difference at the time of activation.

  As described above, in this embodiment, the third control circuit controls the switching timing between the first control circuit 1 that controls the first switch element 4 and the second control circuit 2 that controls the second switch element 6. By configuring the control circuit 15 to be connected and controlling on / off of both the switch element 4 and the switch element 6, it is possible to determine the starting order of boosting and inverting boosting.

  The present invention is applied to a power supply circuit that requires a multi-output power supply, and is particularly useful for a time-division type power supply circuit in which a booster circuit and an inverting booster circuit are realized by a single choke coil.

1 is a circuit configuration diagram of a power supply circuit according to an embodiment of the present invention. The figure which shows the output voltage waveform at the time of starting of the power supply circuit which concerns on this embodiment Circuit diagram of conventional power supply circuit Waveform diagram of conventional power circuit Output waveform diagram at startup of conventional power supply circuit

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 1st control circuit 2 2nd control circuit 3 Power supply terminal 4 1st switch element 5 Choke coil 6 2nd switch element 7, 8 Rectifier diode 9, 10 Smoothing capacitor 11 Inverted boost output terminal 12 Boost output Terminal 13 Inverted Boost Output Feedback Terminal 14 Boost Output Feedback Terminal 15 Third Control Circuit

Claims (1)

  A control circuit having one choke coil and a power supply terminal for supplying power to the choke coil, connecting a switch element and a rectifier element between the choke coil and the power supply terminal, and controlling an on / off period of the switch element And a booster circuit having a control circuit for controlling an on / off period of the switch element by connecting another switch element and a rectifier element between the other end of the choke coil and the ground. The circuit includes a control circuit that operates the boosting and the inverting boosting in the control circuits that control the on / off periods of the switch elements provided at both ends of the choke coil at a predetermined time difference. Power supply circuit.

Images