JP2016152671A - Power supply device with rush current protection function - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a power supply device with a rush current protection function capable of surely limiting rush current even when a power switch is turned on immediately after it is turned off.SOLUTION: A power supply device with a rush current protection function comprises: a first rectification circuit 10 which rectifies the AC voltage input from an AC power supply AC1 via a power switch SW1; a first capacitor C1 which smooths an output voltage of the first rectification circuit; a DC/DC converter 20 which converts the DC voltage smoothed by the first capacitor to a prescribed DC voltage; a current limiting resistive element R connected between the first rectification circuit and the first capacitor; a switch element SW2 for short-circuiting the current limiting resistive element; and a control unit 30 which controls the switch element. The power supply device further includes a second rectification circuit 15 connected to the AC power supply in parallel to the first rectification circuit, and a second capacitor C2 which smooths the output voltage of the second rectification circuit and whose capacity is set smaller than the capacity of the first capacitor. The control unit controls the switch element SW2 on the basis of the output voltage of the second capacitor.SELECTED DRAWING: Figure 1

Description

  The present invention is smoothed by a first rectifier circuit that rectifies an AC voltage input from an AC power supply via a power switch, a first capacitor that smoothes an output voltage of the first rectifier circuit, and the first capacitor. A DC / DC converter that converts a DC voltage into a predetermined DC voltage; an inrush current protection element connected between the first rectifier circuit and the first capacitor; and a switch element that short-circuits the inrush current protection element; The present invention also relates to a power supply device with an inrush current protection function, comprising a control unit that controls the switch element.

  In Patent Document 1, a current exceeding a certain level is connected between a cathode of a diode connected to the secondary side of a transformer and a smoothing capacitor for the purpose of obtaining a power supply circuit capable of suppressing an inrush current when the power switch is turned on. A power supply circuit is disclosed that includes an overcurrent protection element in which the resistance value increases abruptly when current flows.

  Japanese Patent Application Laid-Open No. 2004-26883 can prevent wasteful power consumption and damage in the current limiting resistor even when control is performed to operate the load immediately after power-on or when an abnormality such as a short circuit occurs in the load. An inrush current prevention circuit is disclosed.

  The inrush current prevention circuit includes a current limiting resistor that is connected between a load and a power source connected in parallel with a capacitive element, and a current limiting resistor, and is connected in parallel with the current limiting resistor between both ends of the current limiting resistor. It is equipped with bypass means that can switch between short-circuit and open-circuit, and load voltage detection means that detects the voltage on the load side of the current limiting resistor, and is detected by the load voltage detecting means with both ends of the current limiting resistor open. When the voltage on the load side becomes equal to or higher than a predetermined voltage, the bypass means is configured to short-circuit between both ends of the current limiting resistor to bypass.

  As shown in FIG. 3, generally, the rectifier circuit 10 rectifies the AC voltage input from the AC power supply AC1 through the power switch SW1, the capacitor C that smoothes the output voltage of the rectifier circuit 10, and the capacitor C. A power supply device 100 with an inrush current protection function including a DC / DC converter 20 that converts the direct current voltage into a predetermined direct current voltage is used. In some cases, a power supply circuit for supplying power to another load may be connected as the load L connected to the power supply device 100 with the inrush current protection function. For example, an RF power supply circuit that supplies power to the plasma apparatus.

  In order to keep the input voltage to the DC / DC converter 20 stable even when the input AC voltage fluctuates, an electrolytic capacitor C having a large capacity is used as a smoothing capacitor.

  In such a power supply device 100 with an inrush current protection function, the current limiting resistance element R is provided between the rectifier circuit 10 and the capacitor C, and the switch element SW2 that short-circuits the current limiting resistance element R is the current limiting resistance element R. Is connected in parallel, and when the power switch SW1 is turned on, the switch element SW2 is turned off and the load L is supplied with power through the current limiting resistor element R to suppress the inrush current. Thereafter, the voltage across the capacitor C is predetermined. The control unit 30 is provided to turn on the switch element SW2 and short-circuit the current limiting resistance element R when a predetermined time elapses after exceeding the threshold voltage.

  In FIG. 4, after the power switch SW <b> 1 is turned on, the switch element SW <b> 2 is turned off and the inrush current to the load is suppressed by the current limiting resistor element R, and then the switch element SW <b> 2 is turned on by the control unit 30. The timing at which the resistance element R is short-circuited is shown.

Japanese Patent Laid-Open No. 11-178195 JP 2012-143110 A

  However, as shown in FIG. 4, since the capacity of the smoothing capacitor C is large, depending on the characteristics of the load L connected to the DC / DC converter 20, even if the power switch SW1 is turned off, the voltage across the capacitor C is In some cases, a state higher than the threshold voltage may be maintained, and when the power switch SW1 is turned on again during the delay time until the voltage across the capacitor C drops below the threshold voltage, the switch element SW2 is turned on immediately, and an excessive inrush current is generated. There was a problem of flowing.

  In view of the above-described problems, an object of the present invention is to provide a power supply device with an inrush current protection function capable of reliably limiting an inrush current even when the power switch is turned on immediately after being turned off.

  In order to achieve the above-mentioned object, the first characteristic configuration of the power supply device with inrush current protection function according to the present invention is input from an AC power source through a power switch as described in claim 1 of the claims. A first rectifier circuit that rectifies the AC voltage that has been generated, a first capacitor that smoothes the output voltage of the first rectifier circuit, and a DC / DC that converts the DC voltage smoothed by the first capacitor into a predetermined DC voltage A converter; a current limiting resistance element connected between the first rectifier circuit and the first capacitor; a switching element that short-circuits the current limiting resistance element; and a control unit that controls the switching element. An inrush current protection device comprising: a second rectifier circuit connected to the AC power supply in parallel with the first rectifier circuit; and an output voltage of the second rectifier circuit is smoothed by a capacitance of the first capacitor. And a second capacitor set to the capacitance, the control unit is in that it is configured to control the switching element based on the output voltage of the second capacitor.

  Since the capacity of the second capacitor that smoothes the output voltage of the second rectifier circuit is smaller than the capacity of the first capacitor, the capacitor is quickly discharged when the power switch is turned off. Therefore, even when the power switch is turned on again, the switch element can be reliably turned off immediately after that, and the inrush current can be suppressed.

  In the second feature configuration, in addition to the first feature configuration described above, the current limiting resistance element is interposed in a ground line of the first rectifier circuit, and the switch element is provided. IGBT is used.

  Since the switch element is connected in parallel to the current limiting resistance element interposed in the ground line of the first rectifier circuit, it is possible to enter the load without providing a separate power supply circuit for controlling the gate voltage of the IGBT. While the current flows and the output voltage of the second capacitor is low, the IGBT gate voltage is applied to turn off the IGBT by applying a low level voltage, and if the inrush current decreases and the output voltage of the second capacitor increases, the IGBT The IGBT can be turned on by raising the gate voltage.

  According to the third feature configuration, in addition to the first or second feature configuration described above, the first rectification circuit is configured by a full-wave rectification circuit, and the second rectification circuit is provided. Is composed of a half-wave rectifier circuit.

  Although it is necessary to supply sufficient power to the DC / DC converter for supplying power to the load by a full-wave circuit, the second capacitor is smoothed in order to detect the period during which the inrush current flows after the input of the power source or the like. A half-wave rectifier circuit is sufficient as the second rectifier circuit for supplying only the electric power, whereby the circuit can be simplified and the cost can be reduced.

  As described above, according to the present invention, it is possible to provide a power supply device with an inrush current protection function capable of reliably restricting an inrush current even when the power switch is turned on immediately after being turned off. It was.

Circuit diagram of power supply device with inrush current protection function according to the present invention Timing chart showing operation of power supply device with inrush current protection function according to the present invention Circuit diagram of conventional power supply with inrush current protection function Timing chart showing the operation of a conventional power supply device with inrush current protection function

Hereinafter, a power supply device with an inrush current protection function according to the present invention will be described with reference to the drawings.
FIG. 1 shows a circuit block of a power supply device 100 with an inrush current protection function according to the present invention.

  The power supply device 100 with an inrush current protection function includes a first rectifier circuit 10 that rectifies an AC voltage input from the AC power supply AC1 via the power switch SW1, and a first capacitor C1 that smoothes the output voltage of the first rectifier circuit 10. A DC / DC converter 20 that converts the DC voltage smoothed by the first capacitor C1 into a predetermined DC voltage, and a current limiting resistor element R connected between the first rectifier circuit 10 and the first capacitor C. The switch element SW2 for short-circuiting the current limiting resistor element R and the control unit 30 for controlling the switch element SW2 are provided.

  Then, the second rectifier circuit 15 connected to the AC power supply SC1 in parallel with the first rectifier circuit 10 and the second rectifier circuit 15 which smoothes the output voltage of the second rectifier circuit 15 and is set to have a smaller capacity than the capacity of the first capacitor C1. The control unit 30 is configured to control the switch element SW2 based on the output voltage of the second capacitor C2.

  As shown in FIG. 2, immediately after the power switch SW1 is turned on, the control unit 30 detects the voltage across the second capacitor C2, and turns off the switch element SW2 when the value is equal to or lower than a predetermined threshold voltage. The DC / DC converter 20 and the load L are supplied with power through the current limiting resistor R. Thus, the inrush current to the load side when the power switch SW1 is on is suppressed by the current limiting resistor R.

  Immediately after the voltage across the capacitor C2 exceeds the threshold, or after a predetermined time has elapsed after the voltage across the capacitor C2 exceeds the threshold, the control unit 30 turns on the switch element SW2 to short-circuit the current limiting resistor R.

  When the power switch SW1 is turned off in this state, the voltage across the first capacitor C1 remains higher than the threshold voltage for a long time, but the voltage across the second capacitor C2 quickly drops below the threshold voltage.

  Therefore, even when the power switch SW1 is quickly turned on again, the voltage across the second capacitor C2 is lower than the threshold voltage, so that the switch element SW2 is not turned on by mistake.

  That is, since the capacity of the second capacitor C2 that smoothes the output voltage of the second rectifier circuit 15 is smaller than the capacity of the first capacitor C1, it is discharged quickly when the power switch SW1 is turned off. Even when SW1 is turned on, the switch element SW2 can be reliably turned off immediately after that, and the inrush current can be suppressed.

  It is preferable that the current limiting resistor element R is interposed in the ground line G of the first rectifier circuit 10 and the IGBT is used for the switch element SW2, and the current limiting resistor element R is interposed in the ground line G of the first rectifier circuit 10. Since the switch element SW2 is connected in parallel to the resistor element R, an inrush current flows through the load and the output voltage of the second capacitor C2 is reduced without providing a separate power supply circuit for controlling the gate voltage of the IGBT. While the voltage is low, a low level voltage is applied to the gate voltage of the IGBT to turn off the IGBT. When the inrush current decreases and the output voltage of the second capacitor C2 increases, the gate voltage of the IGBT is increased to turn on the IGBT. be able to.

  The first rectifier circuit 15 is preferably composed of a full-wave rectifier circuit, and the second rectifier circuit 15 is preferably composed of a half-wave rectifier circuit. The DC / DC converter 20 for supplying power to the load L needs to be supplied with sufficient power by the full-wave current circuit 10, but the second capacitor is used to detect the period during which the inrush current flows after the input of the power source or the like. The second rectifier circuit 15 that supplies power sufficient to smooth C is sufficient as a half-wave rectifier circuit, which can simplify the circuit and reduce costs.

  The above-described embodiments are merely examples of the present invention, and the present invention is not limited to the specific examples described above. The specific configuration of each block and the like are within the scope of the present invention. Needless to say, the design can be changed as appropriate.

10: first rectifier circuit 15: second rectifier circuit 20: DC / DC converter 30: controller 100: power supply device with inrush current protection function AC1: AC power supply C1: first capacitor C2: second capacitor R: current limiting resistor Element SW1: Power switch SW2: Switch element

Claims (3)

A first rectifier circuit that rectifies an AC voltage input from an AC power source via a power switch, a first capacitor that smoothes an output voltage of the first rectifier circuit, and a DC voltage smoothed by the first capacitor is predetermined. A DC / DC converter that converts the direct current voltage into a direct current voltage, a current limiting resistance element connected between the first rectifier circuit and the first capacitor, a switching element that short-circuits the current limiting resistance element, and the switching element A power supply device with an inrush current protection function comprising a control unit for controlling
A second rectifier circuit connected to the AC power supply in parallel with the first rectifier circuit; and a second capacitor set to a capacity smaller than that of the first capacitor by smoothing an output voltage of the second rectifier circuit. Prepared,
The control unit is a power supply device with an inrush current protection function configured to control the switch element based on an output voltage of the second capacitor.   2. The power supply device with an inrush current protection function according to claim 1, wherein the current limiting resistor element is interposed in a ground line of the first rectifier circuit, and an IGBT is used for the switch element.   3. The power supply device with an inrush current protection function according to claim 1, wherein the first rectifier circuit is configured by a full-wave rectifier circuit, and the second rectifier circuit is configured by a half-wave rectifier circuit.

Images