KR200144429Y1 - Over Current Protection Circuit - Google Patents

Abstract

The present invention relates to an overcurrent protection circuit of a power supply device, and more particularly to an overcurrent protection circuit for detecting an input current and an output current to cut off a power supply when an overcurrent occurs.

In order to solve the inconvenience of changing the fuse when the fuse is blown by the over current, the power supply detects the over current of the input power or the over current of the load and cuts off the power supply. To protect.

Description

Over Current Protection Circuit

1 is a conventional overcurrent protection circuit diagram.

2 is another conventional overcurrent protection circuit diagram.

3 is an overcurrent protection circuit of an embodiment applied to the present invention.

4 is an overcurrent protection circuit of another embodiment applied to the present invention.

* Explanation of symbols for main parts of the drawings

40: inlet plug 42: switching unit

44: input current detector 48: load current detector

50: rectifier 52: load

54: switch 56: triac

The present invention relates to an overcurrent protection circuit of a power supply device, and more particularly, to an overcurrent protection circuit for detecting an input current and an output current to cut off a power supply when an overcurrent occurs.

In general, when a home appliance or an industrial electronic device (hereinafter referred to as a 'load') is overloaded, an overcurrent of more than the rated current is applied and a load may be damaged. Therefore, when the load is overloaded, an overcurrent protection circuit is required to protect the load by cutting off the power supplied from the outside.

FIG. 1 is a power cutoff circuit using a fuse, and AC power input through the inlet plug 10 is converted into a desired output power through the power control unit and the transformer unit 14. The power output from the power control unit and the transformer unit 14 is rectified by the constant current 18 including the diode D1 and the capacitor C1 and applied to the load 20. At this time, when an overcurrent is generated from the power input through the inlet plug 10, the fuse 12 is blown to open the line (L1) and the line (L3) to cut off the supply power input through the inlet (10). In addition, when the overload state from the load 20, the fuse 16 is blown by the overcurrent that is increased above the rated current to open the line (L4) and the line (L5) to output from the power control unit and the transformer (14) The supply power transmitted to the load 20 is cut off.

However, the conventional circuit as shown in FIG. 1 has the inconvenience of replacing the blown fuses 12 and 16 at every power-off operation.

Another conventional overcurrent circuit for solving such a problem is disclosed in FIG. In FIG. 2, the inlet plug 10 draws power from the outside and transmits the power through the first and second transmission lines L10 and L14. In the state where the power is input through the inlet plug 10, the operator loads ( When the switch 34 is ounce-positioned to supply power to the 32, the triac 36 is operated by the overcurrent detecting unit 24 which starts operation from the moment the switch 34 is pressed. Therefore, even though the switch 34 is turned off because the current path is formed, power is continuously supplied to the load 32 through the power control unit and the transformer unit 26, and when the overload is detected by the load 32, the overcurrent detection is performed. By stopping the operation of the triac 36 by the unit 24 is to cut off the power supplied to the load (32).

Referring to the overcurrent detecting unit 24, the first transistor Q1 is switched according to the voltage Q1 across the resistor R1, and the voltage V1 across the resistor R1 is 0.7, the transistor operating voltage. If it is not an overload state that is less than V, the signal is turned off. On the contrary, when the voltage across both resistors R1 is 0.7V or more, it is switched on.

The second transistor Q2 performs the switching operation according to whether the potential difference between the transmission line L13 and the connection point 1, that is, the potential difference VEB2 between the emitter and the base is 0.7V or more, which is an operating voltage. To control the triac 50. When the first transistor Q1 is not in an overload state in which the first transistor Q1 is off, the potential difference VEB2 between the transmission line L13 and the connection point 1 is turned on (Turn-On) to be greater than 0.7 V, the operating voltage. The power supply on the line L13 is applied to the gate of the triac 36 via the line 3, and conversely, between the transmission line L13 and the connection point 1 when the transistor Q1 is in the overcurrent state in the on state. Since the potential difference VEB2 becomes smaller than the operating voltage 0.7V, the supply power on the transmission line L13 does not pass to the line 3.

The resistor R2 is a resistor used to turn on the transistor Q2 when it is not overloaded by attenuating the power supply on the transmission line L12.

Therefore, transistor Q1 and resistor R1 act as means for detecting overcurrent on transmission line L12, and transistor Q2 and resistor R2 serve as means for controlling triac 36. The power control and transformer unit 26, the fuse 28, and the rectifier unit 30, which are not described herein, are the same as those in FIG.

The conventional circuit as shown in FIG. 2 can control the primary overcurrent by cutting off the input power when an overcurrent is generated with respect to the primary input current of the transformer, but when the overcurrent occurs in the secondary side of the transformer, the fuse 28 is changed as shown in FIG. The uncomfortable problem to be fitted was not solved.

Accordingly, an object of the present invention is to provide an overcurrent protection circuit that cuts off the input power when an overcurrent occurs for the input power and the output power in the power supply device.

Another object of the present invention is to provide an overcurrent protection circuit for detecting a primary input current and a secondary load current of a transformer in a power supply device to cut off power when an overcurrent occurs.

The present invention for achieving the above object is a power supply control means for controlling the power supply by a predetermined overcurrent detection signal by inputting the supply power, and the overcurrent detection signal by detecting the relative input current supplied through the power supply control means An input current sensing means for controlling the operation of the power supply control means according to the output of the power supply, a power control and transformer means for inputting the power supplied through the power supply control means and converting it into a desired power; And a load current sensing means for controlling the operation of the power supply control means according to the output of the overcurrent sensing signal by detecting the current state of the load by inputting the power output from the control and transformer means.

Hereinafter, the present invention will be described in detail with reference to the accompanying drawings.

3 is an over-current protection circuit applied to an embodiment of the present invention, the inlet plug 40 for inputting power supplied from the outside, and the power drawn through the inlet plug 40 to the load 52 It is connected between the first and second transmission lines L21 and L22 for transmission and the first transmission line L21 and the third transmission line L23 to supply initial power, and to supply power by a predetermined overcurrent detection signal. A power supply control unit 42 comprising a switch 54 and a triac 56 for controlling the supply and an input current state on the third transmission line L23 are detected to output an overcurrent detection signal. Input current sensing unit 44 consisting of transistors Q1-Q2 and resistors R1 and R2 for controlling the operation of the triac 56, and the power supplied through the triac 56 A power control unit and transformer unit 46 for converting and outputting the desired power; Transistor Q3 for controlling the operation of the triac 56 according to the output of the overcurrent detection signal by detecting the load current on the fourth transmission line L24 by inputting the voltage output from the power supply control section and the transformer section 46. ), A load current detection unit 48 including a resistor R3 and an inverter I1, an input overcurrent detection signal output from the input current detection unit 44, and a load output from the load overcurrent detection unit 48. An AND gate 58 that inputs an overcurrent detection signal to the gate of the triac 56 and a diode that receives and rectifies the power output from the power control and transformer unit 46 to output the load to the load 52. It consists of the rectification part 50 which consists of D1 and capacitor C1.

Here, the input current sensing means includes a transistor (Q) 1 having an emitter connected to the switch 54, a base terminal of the transistor Q1 connected to the emitter, and a base terminal connected to the collector terminal of the transistor Q1. To the connection point of the transistor Q2 to be connected, the resistor R1 connected between the emitter terminal of the transistor Q1 and the base terminal, and the collector terminal of the transistor Q1 and the base terminal of the transistor Q2. It consists of a resistor (R2) connected.

In addition, the load current detecting means is connected to the Zen 4 transmission line (L24) connected to the rectifier 50, the resistor R3, the emitter terminal is connected to the fourth transmission line (L24), the resistance ( A transistor Q3 having a base connected to R3) and an inverter I1 connected to a collector of the transistor Q3 and outputting a load overcurrent detection signal.

Hereinafter, an embodiment of the present invention will be described in detail with reference to FIG. 3.

The inlet plug 40 draws power from the outside and transmits it through the first and second transmission lines L21 and L22. In the state where the power is input through the inlet plug 40, the operator supplies power to the load 52. When the switch 54 is ounce-shifted to supply the triac, the triac 56 is operated by the input overcurrent sensing unit 44 which starts operation from the moment the switch 54 is pressed. Therefore, even when the switch 54 is turned off because the current path is formed, power is continuously supplied to the load 52 through the power control and transformer unit 46. At this time, when the overcurrent flows on the third transmission line L23, the input current detector 44 stops the operation of the triac 56 to cut off the power supplied to the load 52.

Referring to the input current detector 44, the transistor Q1 is switched according to the voltage V1 across the resistor R1, and the voltage V1 across the resistor R1 is applied to the transistor Q1. The transistor Q1 is turned on when the voltage V1 of the resistor R1 is overcurrent when the voltage across both resistors R1 is 0.7V or more.

The second transistor Q2 has a potential difference between the third transmission line L23 and the node a, that is, the potential difference VEB2 between the emitter and the bay TM (Base) is 0.7 V or more, which is an operating voltage. The switching operation is performed to control the triac 56 via the end gate 58. When the transistor Q1 is not in an off state, the potential difference VEB2 between the third transfer line L23 and the node a is turned on to be greater than 0.7 V, the operating voltage, thereby turning on the transistor. The supply power on the third transmission line L23 is applied to the AND gate 58 via the line b. As a result, the AND gate 58 outputs a high signal to the gate of the triac 56. In this case, it is assumed that the load current detector 48 is in a normal state and a high signal is output.

On the contrary, since the potential difference VEB2 between the transmission line L23 and the node a becomes smaller than the operating voltage 0.7V when the transistor Q1 is in the overcurrent state, the supply power on the transmission line L23 b) do not pass through. Therefore, the AND gate 58 outputs a low signal to turn off the triac 56 to cut off the power supply.

In addition, the resistor R2 is a resistor used to turn on the transistor Q2 when it is not overloaded by attenuating the supply power on the third transmission line L23.

Therefore, transistor Q1 and resistor R1 act as a means for detecting overcurrent on third transmission line L23, and transistor Q2 and resistor R2 act as means for controlling triac 56. do.

In addition, the power supply control and transformer unit 46 inputs the power input through the inlet plug 40 and converts it to the desired power output. The power output from the power control and transformer unit 46 is applied to the rectifier 50 through the fourth transmission line L24, rectified, and then applied to the load 52. At this time, when an overcurrent flows from the load 52, an overcurrent flows on the fourth transmission line L24, and the power supplied to the load 52 by stopping the operation of the triac 56 by the load overcurrent detector 48. Will be blocked.

Referring to the load current detection unit 48, the transistor Q3 is switched according to the voltage V2 across the resistor R3, and the voltage V2 across the resistor R3 is operated by the transistor Q3. When the voltage is 0.7 V or less, that is, in an overcurrent state, the transistor Q3 is turned off and inverted through the inverter I1 to output a high signal, and the input current from the input current detector 44 is normal. In this state, the triac 58 is normally turned on.

On the contrary, when the voltage V1 of the resistor R3 is in an overcurrent state of 0.7 V or more, the transistor Q3 is turned on. When the transistor Q3 is turned on, the power on the fourth transmission line L24 is inverted to a low signal through the inverter I1 and is applied to the AND gate 58, so the AND gate 58 outputs a low signal. Therefore, the triac 58 is turned off to cut off the supply of input power to stop the supply of power to the load 52.

Therefore, the transistor Q3 and the resistor R3 operate as a means for detecting an overcurrent on the fourth transmission line L24, and the inverter I1 serves as a means for controlling the triac 56.

Therefore, the triac 56 is turned off when the input overcurrent is detected from the input current detector 44 or the load overcurrent is detected by the load current detector 48 to cut off the supply of input power.

4 is an overcurrent protection circuit diagram according to another embodiment of the present invention. The inlet plug 40 for inputting power supplied from the outside and the initial power supplied from the inlet plug 40 are supplied with a predetermined overcurrent. A switching unit 42 including a switch 54 and a triac 56 for controlling a power supply by a detection signal, and an input current state supplied through the switching unit 42 to detect an overcurrent Through an input current sensing unit 44 consisting of transistors Q1-Q2 and resistors R1 and R2 for controlling the operation of the triac 56 according to the output of the sensing signal, and through the triac 56 Inputs the power supplied and converts it into a desired power and outputs the power control and transformer unit 46, and the power output from the power control and transformer unit 46 to input the load current on the fourth transmission line (L24) Detect over current A load current sensing unit 48 comprising a transistor Q3, a resistor R3, and a photocoupler PC1 for controlling the operation of the triac 56 according to the output of the ground signal; It is composed of a rectifier 50 composed of a diode (D1) and a capacitor (C1) for receiving the power output from the unit 46 to rectify and output to the load (52).

With reference to FIG. 4 described above, another preferred embodiment of the present invention will be described in detail.

The inlet plug 40 draws power from the outside and sends it to the load 52 through the triac 56 and the power control and transformer unit 46, and in the state where the power is input through the inlet plug 40. When the operator ounces the switch 54 to supply power to the load 52, the triac 56 is operated by the input overcurrent detector 44 which starts operation from the moment the switch 54 is pressed. Done. Therefore, even when the switch 54 is turned off because the current path is formed, power is continuously supplied to the load 52 through the power control and transformer unit 46. At this time, when the overcurrent flows on the third transmission line L23, the over current detecting unit 44 stops the operation of the triac 56 to cut off the power supplied to the load 52.

The input current detector 44 has been described in detail with reference to FIG. 2 and will not be described below.

In addition, the power supply control and transformer unit 46 inputs the power input through the inlet plug 40 and converts it to the desired power output. The power output from the power control and transformer unit 46 is applied to the rectifier 50 through the fourth transmission line L24, rectified, and then applied to the load 52. At this time, when an overcurrent flows from the load 52, an overcurrent flows on the fourth transmission line L24, and the power supplied to the load 52 by stopping the operation of the triac 56 by the load overcurrent detector 48. Will be blocked.

Referring to the load current detecting unit 48, the transistor Q3 is switched according to the voltage V2 across the resistor R3, and the voltage V2 across the resistor R3 is applied to the transistor Q3. When the operating voltage is 0.7V or less, that is, in an overcurrent state, the transistor Q3 is turned off and the photocoupler PC1 is turned off. When the photocoupler PC1 is off, the base of the transistor Q2 is turned low, and the transistor Q2 is turned on to normally turn on the triac 56 to supply input power.

On the contrary, when the voltage V1 of the resistor R3 is in an overcurrent state of 0.7 V or more, the transistor Q3 is turned on. When the transistor Q3 is turned on, the power supply on the fourth transmission line L24 turns on the photodiode of the photocoupler PC1 to turn on the light receiving transistor. When the light receiving transistor is turned on, a high signal is applied to the base of the transistor Q2 to turn off the transistor Q2. When the transistor Q2 is turned off, the triac 58 is turned off to cut off the supply of input power.

Therefore, the triac 56 is turned off when the input current detection unit 44 detects an input overcurrent or the load current detection unit 48 detects a load current, thereby interrupting supply of power.

As described above, the present invention detects an overcurrent state of an input power source or an overcurrent state of a load in a power supply device, and thus cuts off a supply power supply. Therefore, the power supply device can quickly respond in response to an overcurrent to cut off the power supply, thereby protecting the source device. In addition, there is an advantage that can eliminate the inconvenience to be replaced by the use of fuses.

Claims (4)

In the over-current protection circuit of the power supply device, input power supply to control the power supply by a predetermined over-current detection signal power supply control means, and detects the input current state supplied through the power supply control means to detect the overcurrent detection signal An input current sensing means for controlling the operation of the power supply control means according to the output of the power supply, a power control and trans means for inputting the power supplied through the power supply control means and converting the power to a desired power; An overcurrent protection circuit comprising: a load current sensing means for detecting the current state of the load by inputting the power output from the control and transformer means and controlling the operation of the power supply control means according to the output of the overcurrent sensing signal; . 2. The load current detecting means according to claim 1, wherein the load current detecting means comprises: a transistor Q3 for detecting a current state of a load by inputting a power output from the power supply control and transformer means, and a load overcurrent from the transistor Q3 being detected; An overcurrent protection circuit comprising: a photocoupler (PC1) for generating a power cutoff control signal at time of operation. An overcurrent protection circuit of a power supply device, comprising: a triac (56) for inputting power supplied from the outside to cut off power supply by a predetermined overcurrent detection signal, and an input current from a power output through the triac (56) The input current detecting unit 44 for controlling the operation of the triac 56 according to the output of the overcurrent detection signal by detecting a state, and the power supplied through the triac 56 is input to convert to the desired power Operation of the triac 56 in accordance with the output of the over-current detection signal by detecting the state of the load current by inputting the output power control and transformer unit 46, and the power output from the power control and transformer unit 46 The load current detection unit 48 for controlling the input, the input over current detection signal output from the input current detection unit 44 and the load over current detection signal output from the load over current detection unit 48 And an AND gate (58) for input to the gate of the triac (56). 4. The load current detecting means according to claim 3, wherein the load current detecting means comprises: a transistor Q3 for detecting a current state of a load by inputting a power output from the power control and transformer means; and an overcurrent detection signal output from the transistor Q3. And an inverter (I1) for inverting and outputting the power cutoff control signal.