KR100189890B1 - A protecting apparatus for over-current of the power supply with a great current - Google Patents

Abstract

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a protection device for a large current output device, and more particularly, an overcurrent blocking high current output device for blocking and protecting overcurrent generated from an AC, DC motor driving device such as a servo and an inverter, a heater, an air conditioner, and the like It relates to a protection device.

That is, in the large current output device protection device according to the present invention, the characteristics of the semiconductor switching device, that is, the magnitude of the voltage drop generated between the emitter and the collector when the bias current is applied to the base or the gate is linear to the magnitude of the bias current. By using this characteristic, it detects this voltage drop and if it falls below a certain value, it judges that overcurrent occurs and shuts off the driving circuit and simultaneously sounds the alarm and protects the circuit. Therefore, the protection device to protect the circuit is formed integrally with the driving unit to ensure reliability in circuit protection.

Description

Overcurrent Blocking Large Current Output Device Protection Devices

1 is a schematic block diagram of a conventional high current output device protection device.

2 is a circuit diagram of a high current output device protection device according to the present invention.

* Explanation of symbols for main parts of the drawings

1: first driving unit 2: second driving unit

3: first power transistor section 4: second power transistor section

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a protection device for a large current output device, and more particularly, an overcurrent blocking high current output device for blocking and protecting overcurrent generated from an AC, DC motor driving device such as a servo and an inverter, a heater, an air conditioner, and the like It relates to a protection device.

1 is a schematic block diagram of a conventional high current output device protection device. Looking at the block diagram and its configuration and operation as follows.

The first driving signal and the second driving signal are amplified by the first driving unit 1 and the second driving unit 2, respectively, to output semiconductor devices (the first power transistor unit 3 and the second power transistor unit 4). ), The output terminal semiconductor element flows a current into a load such as an electric motor to generate a rotational force.

Such a large current output device is a current sensor using a Hall element or the like on an output line to a load (motor), and detects an output current and applies it to an overcurrent detector. When an overcurrent occurs, the output signal of the overcurrent detector is applied as an interrupt such as a CPU to generate an output control signal to block the operation of the first driver 1 and the second driver 2.

In this type of large current output device, the driver and the protection device (circuit) are separated, and the element is protected by using a feedback signal for the current sensing signal of a current sensor such as a hall element.

However, such a large current output device protection device has a disadvantage of being affected by external noise or the response speed of the processing circuit is reduced, thereby reducing the stability of the protection operation.

SUMMARY OF THE INVENTION The present invention has been made to improve the above problems, and an object thereof is to provide a stable high current output device protection device capable of swiftly responding to overcurrent without removing the influence of external noise.

In order to achieve the above object, a high current output device protection device according to the present invention includes a semiconductor switching means for supplying current to a load to be driven, and a high current device provided with driving means for driving the semiconductor switching means. An over-current detecting means connected to the switching means for detecting a voltage across the semiconductor switching means to sense whether an overcurrent flows through the switching means, and is turned on in accordance with the voltage sensed at both ends of the semiconductor switching means. An over-current blocking means provided with a switching means for turning off said driving means by controlling a bias voltage of said means, said over-current blocking means adapted to be connected with a bias input terminal of said driving means to block said over-current when said over-current sensing means senses said over-current; And the above Is connected to the switching means of the current blocking means is characterized in that the alarm means is provided with a to let you know when the overcurrent flows.

In the present invention, it is preferable that the overcurrent alarm means includes a photo coupler which is connected to the overcurrent interruption means and generates and transmits an alarm signal by a current flowing when the overcurrent interruption means is turned on. And a resistor and a capacitor connected to a bias input terminal of the transistor, a bias applying end of the transistor, a connection node of the resistor and a capacitor, and a voltage detection terminal of the semiconductor switching means and are energized when a reverse voltage of a predetermined voltage or more is applied. Preferably, a constant voltage diode is provided, wherein the overcurrent sensing means connects a resistor and a diode in series between the voltage detection terminal of the semiconductor switching means and the constant voltage diode, and the connection direction of the diode is to detect the voltage of the semiconductor switching means. In the case of the overvoltage, the overvoltage is not transmitted to the bias input terminal of the switching means, and when the overcurrent flows through the semiconductor switching means, when the voltage detection terminal of the semiconductor switching means is a low voltage, the low voltage is applied to the bias input terminal of the switching means. It is preferable that the drop charged in the capacitor disposed is discharged, and the overcurrent interruption means is connected through an output terminal of the switching means, a bias input terminal of the driving means, a resistor and a diode.

Hereinafter, a high current output device protection device according to the present invention will be described with reference to the drawings.

2 is a circuit diagram of a high current output device protection device according to the present invention. The configuration will be described with reference to this drawing.

When the driving signal is input to the first photo coupler PC1, the driving signal is input to the base terminals of the transistors Q1 and Q2, which are the front ends of the driving unit, respectively. Here, the driving unit is composed of a transistor Q1, a first power transistor Q4, and a second power transistor Q5 to drive the semiconductor switching element IGBT.

As the protection device, the transistor Q3, the zener diode ZD1, and the transistor Q2 are provided as switching means which are integrally connected to the driving units Q1, Q4, Q5. A photo coupler PC2 for sounding an alarm is connected to the collector of the driving block transistor Q3 so that a current flowing when the Q3 is turned on flows through the photo coupler PC2 so that a buzzer signal is generated. The transistor Q2 charges or discharges the capacitor C2 that supplies a bias voltage to the driver blocking transistor Q3.

The high current output device protection device configured as described above operates as follows.

1.Drive

1) When input signal is 'low'

Since the output voltage of the electrically isolated photo coupler PC1 becomes high and the bias voltage of the PNP transistors Q1 and Q2 becomes high, Q1 and Q2 are 'off', and the capacitor C2 is charged through the resistor R4. Since the capacitor C3 disposed at the bias input terminal (base terminal) of the PNP type transistor Q3 is also charged, Q3 remains 'off' so that the photo coupler PC2 does not flow current so that no alarm sounds.

In addition, since Q1 is 'off', driver transistor Q5 of semiconductor switching means IGBT is 'off', driver transistor Q4 of IGBT is 'on' and 'high' is applied to the gate of semiconductor switching element IGBT. Power is output.

2) When input signal is 'high'

Since the output voltage of the electrically isolated photo coupler PC1 is 'low' and the bias voltages of the pnp-type transistors Q1 and Q2 are low, the transistors Q1 and Q2 are 'on'. Therefore, Q4 is 'off' and Q5 is 'on' so that 'low' is applied to the gate of the semiconductor switching element IGBT to cut off the power.

2. When overcurrent occurs

As the output current gradually increases, the voltage between C-E of the semiconductor switching element IGBT decreases to reach the overcurrent detection point. In this case, a path is formed through D2, R6 corresponding to the overcurrent sensing means, and ZD1, R7, C3 connected to the bias input terminal of the switching element Q3, so that the voltage charged in the capacitor C3 is discharged through the path, thereby biasing the Q3. Q3 is turned on by lowering the input (base) voltage. At this time, even when Q1 is turned off and Q4 is turned on, Q3 is turned on. Therefore, the bias input terminal voltage of the driving transistor is lowered through D1 and R8, which constitutes an overcurrent blocking means together with the switching means Q3. The output of the switching element IGBT is cut off automatically.

In addition, since Q3 is 'on', PC2 is 'on' and an overcurrent generation signal to the outside is output. As such, when an overcurrent occurs, an alarm sounds and the driving unit is automatically shut off to protect the circuit.

As described above, the large current output device protection device according to the present invention has the characteristics of the semiconductor switching element, that is, the magnitude of the voltage drop generated between the emitter and the collector generated when the bias current flows through the base or gate. It detects this voltage drop and uses the characteristic of linear proportional to, and if it falls below a certain value, it judges that overcurrent occurs and shuts off the driving circuit and simultaneously sounds the alarm and protects the circuit. A protection device that protects the circuit by cutting off the circuit is formed integrally with the driving unit to ensure reliability in circuit protection.

Claims (5)

A large current device comprising a semiconductor switching means for supplying a current to a load to be driven and a driving means for driving the semiconductor switching means, the high current device being connected to the semiconductor switching means to detect a voltage across the semiconductor switching means. Overcurrent sensing means for sensing whether an overcurrent flows to the switching means, and switching means for turning on the driving means by turning on the voltage according to the voltage sensed at both ends of the semiconductor switching means to control the bias voltage of the driving means. The over-current blocking means made to be connected to the bias input terminal of the driving means to cut off the over-current when the over-current sensing means senses the over-current, and the switching means of the over-current blocking means to know when the over-current flows. High current output device protection device, characterized in that the means of the neck and provided. 2. The protection of a large current output device according to claim 1, wherein said overcurrent alarm means comprises a photo coupler connected to said overcurrent interruption means and generating and transmitting an alarm signal by a current flowing when said overcurrent interruption means is turned on. Device. The switching device according to claim 1, wherein the switching means is connected between a transistor and a resistor and capacitor connected to a bias input terminal of the transistor and a connection between the bias input terminal of the transistor and the resistor and capacitor and a voltage detection terminal of the semiconductor switching means. And a constant voltage diode which is energized when a reverse voltage of a predetermined voltage or more is applied. 6. The method of claim 5, wherein the overcurrent detecting means connects a resistor and a diode in series between the voltage detecting terminal of the semiconductor switching means and the constant voltage diode, and the connection direction of the diode is the overvoltage of the semiconductor switching means. This capacitor is disposed at the bias input terminal of the switching means by the low voltage when the overvoltage is not transmitted to the bias input terminal of the switching means. A high current output device protection device, characterized in that connected to be discharged charge. 2. The apparatus of claim 1, wherein the overcurrent blocking means is connected via an output terminal of the switching means, a bias input terminal of the means, a resistor and a diode.