KR19990053404A - Switching circuit for preventing inrush current of DC / DC converter - Google Patents

Abstract

1. TECHNICAL FIELD OF THE INVENTION

The present invention relates to a switching circuit for preventing inrush current of a DC / DC converter.

2. The technical gist of the invention to solve

SUMMARY OF THE INVENTION The present invention provides a switching circuit for preventing inrush current of a DC / DC converter, which can maintain system power for a predetermined time and can switch system information, and can also prevent an instantaneous inrush current generated when the power is first applied. There is this.

3. Summary of the Solution of the Invention

The present invention provides an inrush current preventing means for preventing the inrush current of the power supply; Drive means for selectively driving a current applied from the inrush current preventing means by using the power source to control driving of a pulse width modulation modulation circuit (PWIC); And a redundancy switching means for stabilizing the power supply and providing a redundancy switching signal.

4. Important uses of the invention

The present invention is used to prevent inrush current and transfer between subsystems, mounted inside an exchange system consisting of two operating modes.

Description

Switching circuit for preventing inrush current of DC / DC converter

The present invention relates to a switching circuit for preventing inrush current of a DC / DC converter. In particular, the present invention is mounted inside an exchange system consisting of a dual (ACTIVE / STAND-BY) operating system to prevent inrush current and switch between subsystems. The present invention relates to a switching circuit for preventing inrush current of a DC / DC converter.

1 is a block diagram of a general DC / DC converter.

As shown in FIG. 1, a general DC / DC converter includes a fuse 1, a redundant switching unit 2 for preventing inrush current, a redundant switching signal detecting unit 3, an EMI (Electro Magnetic Interface) filter, and The input reverse polarity protection part 4, the switching part 5, the transformer 6, the rectification and output filtering part 7, the auxiliary power supply 8, the first control and protection part 9, And a second control and protection unit 10 and a warning unit 11.

The operation of a general DC / DC converter having the structure as described above is as follows.

The power (Vi) input through the fuse (1) prevents the inrush current according to the ON of the power switch (2) in the inrush current prevention redundant switching device (2) to protect the filter and the input reverse polarity (4) It is applied to the switching unit 5 through), and also sends the power cut off signal of the system to the redundant switching signal detection unit 40 to transfer the system information.

Subsequently, the switching section 5 is controlled in the switching circuit by the first control and protection section 9 supplied with the operating voltage by the auxiliary power supply 8 to induce the secondary voltage to the transformer 6. The induced voltage output from the transformer 6 is rectified and filtered by the rectified and output filter 7 at a predetermined DC output voltage and then output. The second control and protection unit 10 detects the output voltage of the rectifying and output filtering unit 7 and outputs a feedback control signal to the first control and protection unit 9 according to the detection result. When an abnormal state, that is, an overcurrent or overvoltage state, the alarm unit 11 is driven to sound an alarm.

FIG. 2 is a block diagram of a conventional redundant switching circuit for preventing inrush current of FIG. 1.

As shown in FIG. 2, the conventional inrush current protection redundant switching device is controlled by a PWM (Pulse Width Modulation) pulse input to the gate of the first switching element Q2 and applied to the transformer T1. FET (field effect transistor) Q2, which is a first switching element for switching the power source Vi, a capacitor C1 connected between the source terminal of the transformer T1 and the FET Q2, and an input power source Vi The gate driving voltage is supplied through the time constant circuit 20 and the time constant circuit 20 connected to both ends of the positive and negative terminals thereof, and the drain terminal is connected to the negative terminal of the capacitor C1 and the FET. The capacitor C1 is connected between the FET Q1, which is the second switching element supplied to the source terminal of Q2, and the source-drain terminal of the FET Q1, and is turned off when the FET Q1 is turned off. A resistor R3 for applying an input power (Vi) having a negative polarity to the source terminal (-) of the FET Q1, and each of the FETs Q1 and Q at the first power-on. A switch SW for turning off the FETs Q1 and Q2 by grounding the gate voltage of 2) to ground, i.e., the negative terminal of the input power source Vi, is provided.

On the other hand, the time constant circuit unit 20 is composed of a voltage divider (R1, R2) for dividing the input power (Vi), the capacitor (C2) and the zener diode (ZD1). D1 and D2 in these description codes are diodes for preventing reverse current when the switch is shorted / opened.

However, in the case of the DC / DC converter equipped with the conventional inrush current prevention redundant switching device as described above, when one of the two subsystems operating in the dual mode is turned off during the active operation. In addition, the system information, which has been active, must be transferred to a system operating in a standby (STAND-BY) system. As the conventional DC / DC converter output is cut off immediately when the switch is turned off, the system information can be transferred. There was a problem that can not afford.

Accordingly, the present invention has been made to solve the above problems, it is possible to transfer the system information by maintaining the power for a predetermined time from the moment the power of the system operating in the active (ACTIVE) state, and also It is an object of the present invention to provide a switching circuit for preventing inrush current of a DC / DC converter that can prevent an instantaneous inrush current generated when the power is first applied.

1 is a block diagram of a typical DC / DC converter.

FIG. 2 is a circuit diagram of a conventional redundant switching device for preventing inrush current of FIG. 1. FIG.

3 is a configuration diagram of an embodiment of a switching circuit for preventing inrush current of a DC / DC converter according to the present invention;

4 is an output voltage timing diagram of a redundant switching device for preventing inrush current of a DC / DC converter according to the present invention.

Figure 5 is a graph showing the change in current with respect to the time of application and non-application of the present invention.

Explanation of symbols on the main parts of the drawings

1: Fuse 2: Redundant switch for preventing inrush current

3: redundant switching signal detection unit 4: filter and input reverse polarity protection unit

5: switching part 6: transformer

7: rectification and output filter 8: auxiliary power supply

9: first control and protection unit 10: second control and protection unit

11: warning unit 310: inrush current prevention unit

320: drive unit 330: redundant switching unit

In order to achieve the above object, the present invention provides a redundant switching device for preventing inrush current of a DC / DC converter, comprising: inrush current preventing means for preventing inrush current of a power applied from the outside; Driving means for selectively applying a current applied from the inrush current preventing means by using the power source; And a redundancy switching means for stabilizing the power source to drive the driving means and delaying a current for a predetermined time to provide a redundancy switching signal.

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

3 is a configuration diagram of an embodiment of a redundant switching circuit for preventing inrush current of a DC / DC converter according to the present invention.

As shown in FIG. 3, the redundant switching device for preventing inrush current of the DC / DC converter of the present invention includes an inrush current prevention unit 310 for preventing inrush current of a power source Vi applied from the outside and the power supply. A drive unit 320 for controlling the driving of the pulse width modulation integrated circuit (PWMIC) by selectively applying a current applied from the inrush current prevention unit 310 by using The redundant switching unit 330 provides a redundant switching signal for switching the system information by delaying a current for a predetermined time.

The inrush current prevention unit 310 includes a capacitor C1 connected between the positive and negative poles of the power supply Vi, resistors R1 and R2 connected in parallel with the capacitor C1, and a gate thereof. A transistor Q1 connected between the R1 and R2, a drain connected to the capacitor C1, and a source connected to the resistor R2, and a resistor R3 connected between the drain and the source of the transistor Q1. And a capacitor C2 connected in parallel to the resistor R2 and a diode D1 connected to the gate of the transistor Q1 to prevent reverse current.

The driving unit 320 includes a first relay switch RY1-1 for switching the current flowing through the diode D1 of the inrush current preventing unit 310 and a current applied through the first relay switch RY1-1. A second relay switch RY1-2 for switching the power supply to an external PWM device, a relay RY1 for controlling the driving of the first and second relay switches RY1-1 and RY1-2, and a power supply; A resistor R6 connected between the positive pole of (Vi) and the relay RY1, the collector is connected to the relay RY1, the base is connected to the redundant switching portion 330, and the emitter is connected to the first and The transistor TR is commonly connected to the second relay switch switches RY1-1 and RY1-2.

The redundant switching unit 330 may include a first switch SW1-1 for switching the power supply Vi, a constant current unit 331 for stabilizing and applying power applied through the first switch SW1-1, A resistor R4 connected to the constant current unit 331, a delay unit 332 connected to the resistor R4 to delay the flow time of the current, and externally switching the current applied through the delay unit 332. It is provided with a second switch (SW1-2) for.

The delay unit 332 includes a capacitor C3 connected between the resistor R4 and the second switch SW1-2 and a resistor R5 connected in parallel with the capacitor C3.

The operation of the inrush current preventing switching circuit of the present invention having the structure as described above will be described in more detail as follows.

When the input voltage is input while the DC / DC converter is turned off, the transistor Q1 is cut off and some voltage is gradually charged to the capacitor C1 only through the resistor R3 having a low resistance value.

At this time, when the switch SW1 is turned on, power is turned on through the first switch SW1-1, and the charging is completed for a predetermined time according to the capacity of the capacitor C2 while passing through the constant current unit 331. The voltage divided by the resistor divided by the resistor R4 and the resistor R5 turns on the transistor TR, and the relay RY1 configured in series is operated to operate the first and second relay switches RY1-1. , RY1-2) The contact point is dropped. Thus, when the contact of the first relay switch RY1-1 disconnects the ON / OFF terminal of the PWM element from the ground GND, the PWM element starts to operate and at the same time the second relay switch RY1-. Since the contact point of 2) is opened, the capacitor C3 is charged through the resistor R1. Since the power is charged to the capacitor C2 at full current, the capacitor C1 is first charged through the resistor R3 during this time. Therefore, when the power is supplied to the resistor R3, an inrush current higher than the value of V1 / R3 cannot occur.

The redundancy switching signal is first sent to the system through the switch SW1-2 at the time of turning off the switch SW1 of the redundancy switching unit 330 to switch the system information, and the switch SW1-1. When the power applied to the circuit is cut off and the discharge is completed by the time constant value through the resistor R5 and the value charged in the capacitor C2, the transistor Q2 is turned off and the first and second relay switches RY1 -1 are turned off. 1, RY1-2 are attached, the PWM device is connected to GND, turned off, and the transistor Q1 is also cut off. Since the output power Vo is maintained for the time that the transistor Q1 is cut off from the moment when the switch SW1 is turned off, system switching can be performed. The diode D1 serves to protect the transistor Q1 according to the reverse polarity power supply, and the resistor R6 limits the current flowing to the relay RY1 and the transistor TR.

4 is an output voltage timing diagram of a redundant switching device for preventing inrush current of a DC / DC converter according to the present invention.

As shown in FIG. 5, looking at the input average current of the DC / DC converter to which the present invention is applied and the DC / DC converter to which the present invention is not applied, it can be seen that a lower average current can be obtained than when not applied.

Although the technical idea of the present invention has been described in detail according to the above preferred embodiment, it should be noted that the above-described embodiment is for the purpose of description and not of limitation. In addition, those skilled in the art will understand that various embodiments are possible within the scope of the technical idea of the present invention.

As described above, the redundant switching device for preventing inrush current according to the present invention is configured to control the inrush current prevention circuit, the driving unit for driving the same, and to maintain the power for a predetermined time to control the operation thereof and to send a switching signal to the system. Even when the power is cut off from one subsystem, the information of the other subsystem can be transferred to maintain a stable system at all times. Also, the switching circuit which is responsible for switching between subsystems is composed together with the inrush current prevention circuit. Inrush current can also be prevented together.

Claims (8)

In the redundant switching device for preventing the inrush current of the DC / DC converter, Inrush current preventing means for preventing the inrush current of the power applied from the outside; Driving means for selectively applying a current applied from the inrush current preventing means by using the power source; And Redundancy switching means for driving the driving means by stabilizing the power supply and delaying a current for a predetermined time to provide a redundant switching signal. Redundant switching device for preventing the inrush current of the DC / DC converter, including. The method of claim 1, The inrush current preventing means, A first capacitor connected between the positive and negative poles of the power supply; First and second resistors connected in parallel with the first capacitor; A transistor connected between the first and second resistors, a drain connected to the first capacitor, and a source connected to the second resistor; A third resistor connected between the drain and the source of the transistor; A second capacitor connected in parallel with the second resistor; And Reverse current preventing means connected between the gate of the transistor and the driving means to prevent reverse current Redundant switching device for preventing the inrush current of the DC / DC converter, including. The method of claim 2, The reverse current prevention means, A diode whose anode is connected to the gate of the transistor and whose cathode is connected to the driving means Redundant switching device for preventing the inrush current of the DC / DC converter, including. The method of claim 1, The drive means, First switching means for switching a current applied from the inrush current preventing means; Second switching means for switching the current applied through the first switching means to the outside; Switching control means for controlling the driving of the first and second switching means and for switching the applied current; A resistor connected between the anode of the power supply and the switching control means; And Third switching means for controlling the current applied through the switching control means controlled by the redundant switching means. Redundant switching device for preventing the inrush current of the DC / DC converter, including. The method of claim 4, wherein The first and second switching means, respectively, A relay switch whose driving is controlled by the switching control means Redundant switching device for preventing the inrush current of the DC / DC converter, including. The method of claim 4, wherein The third switching means, A transistor connected to said switching control means, a base connected to said drive means, and an emitter commonly connected to said first and second switching means Redundant switching device for preventing the inrush current of the DC / DC converter, including. The method of claim 1, The redundant transfer means, First switching means for switching the power source; Constant current means for stabilizing and applying the power applied through the first switching means; A first resistor connected to said constant current means; Delay means connected to said first resistor for delaying the flow time of current; And Second switching means for switching the current applied through the delay means to the outside; Redundant switching device for preventing the inrush current of the DC / DC converter, including. The method of claim 7, wherein The delay means, A capacitor connected between the first resistor and the second switching means; And A second resistor connected in parallel to the capacitor Redundant switching device for preventing the inrush current of the DC / DC converter, including.