KR20190128361A - Apparatus for protecting field effect transistor and system for preventing over-current using the same - Google Patents

Abstract

The present invention relates to an apparatus for protecting a field effect transistor and a system for preventing over-current using the same. More specifically, the protecting apparatus in which a field effect transistor (FET) switch part and a resistor part are connected instantaneously increases the resistance value of the resistor part when overcurrent is applied to the FET switch part so that the gate voltage of the FET switch part is stably increased to a normal level.

Description

Field Effect Transistor Protection Device and Overcurrent Protection System Using the Same {APPARATUS FOR PROTECTING FIELD EFFECT TRANSISTOR AND SYSTEM FOR PREVENTING OVER-CURRENT USING THE SAME}

The present invention relates to a field effect transistor protection device and an overcurrent prevention system using the same, and more particularly, when a field effect transistor (FET) switch unit and a resistor unit are connected and an overcurrent is applied to the FET switch unit, A field effect transistor protection device and an overcurrent protection system using the same, which can stably increase the gate voltage of the FET switch unit to a normal level by instantaneously increasing the resistance of the resistor unit.

Field Effect Transistors (FETs) are a type of semiconductor device, and mean a monopolar transistor in which only one carrier (electron or hole) of one polarity is involved in the internal electric conduction process in the semiconductor.

The FET is a unipolar device operated only by one carrier of electrons or holes, and can be used as a voltage amplification device in that it has a large input impedance compared to a junction transistor. In addition, the noise characteristics are good to handle small signals, the manufacturing process is simple and the space occupied in the integrated circuit has the advantage that the packing density can be very high. Due to these advantages, FETs have been applied to various fields.

In general, when FET devices are connected in parallel and used as switching devices, the FET devices are connected by inputting gate signals to the gate terminals of the FET devices connected in parallel to divide the current into FET devices in which current is connected in parallel on the electrical circuit. To flow.

On the other hand, since the FET device cannot be manufactured so that all the characteristics are the same due to various variables such as manufacturing error, the characteristics may be different from each other as soon as each FET device.

Referring to FIG. 1, it can be seen that the FET device may vary in threshold voltage according to the temperature of the FET device and the characteristics of the FET device. There is a problem that an unbalance between FET devices used together may occur due to a difference in device characteristics.

Due to this imbalance, even when a gate signal is simultaneously input to a plurality of FET devices connected in parallel, the time to be in a conductive state is different. In this case, when the conduction time is different immediately after the FET device, an overcurrent flows through one FET device. There is a problem that can damage the cascade, thereby destroying the cascaded FET devices in parallel.

Korean Patent Publication No. 10-2014-0135549

The present invention has been made to solve the above-described problems, and an object of the present invention is to connect a plurality of FET devices and a plurality of resistors connected in parallel, and when an overcurrent is applied to the FET device, the FET device is connected to an overcurrent. An object of the present invention is to provide a field effect transistor protection device and an overcurrent protection system using the same, by increasing resistance of a resistor to block overcurrent, thereby stably increasing a gate voltage of the FET switch to a normal level.

The field effect transistor protection device according to an embodiment of the present invention is connected to a field effect transistor (FET) switch unit and a drain terminal of the FET switch unit located on an electric circuit, and the FET switch It may include a resistor for adjusting the resistance value according to whether or not the negative.

In an embodiment, the FET switch unit may include a plurality of FET elements connected in parallel, and the resistor unit includes a plurality of positive characteristics respectively connected to drain terminals of the plurality of FET elements so as to correspond one-to-one with the plurality of FET devices. It may include a thermistor (PTC).

In one embodiment, the plurality of FET devices may be a P-channel MOSFET (Metal Oxide Semiconductor Field Effect transistor; MOSFET).

In an embodiment, the resistance unit increases the resistance value when the rate of decrease of the drain terminal side voltage value of the FET switch unit exceeds a reference speed after a gate signal is applied to the FET switch unit. When the voltage value reaches a predetermined value, the resistance value may be adjusted to the initial set value.

In an embodiment, the resistor unit increases the resistance value when the temperature value of the electrical circuit exceeds the first reference temperature value after the gate signal is applied to the FET switch unit, and increases the temperature value of the electrical circuit. When it falls below this 2nd reference temperature value, the said resistance value can be adjusted to an initial setting value.

An overcurrent protection system according to an embodiment of the present invention includes a field effect transistor (FET) switch unit located on an electric circuit and a resistor unit connected to a drain terminal of the FET switch unit. And a control unit for diagnosing an abnormality in the FET switch unit using at least one of a field effect transistor protection device and a current value and a voltage value of the FET switch unit, and adjusting the resistance value of the resistor unit based on a diagnosis result. .

The controller may increase the resistance of the resistor unit when the rate of decrease of the drain terminal side voltage value of the FET switch unit exceeds a reference speed after the gate signal is applied to the FET switch unit. When the voltage value of the gate terminal reaches a preset value, the resistance value of the resistor unit may be adjusted to an initial setting value.

The controller may increase the resistance of the resistor unit when the temperature value of the electrical circuit exceeds the first reference temperature value after the gate signal is applied to the FET switch unit. When the temperature value falls below the second reference temperature value, the resistance value of the resistor unit may be adjusted to an initial set value.

The present invention connects a plurality of parallel connected FET devices and a plurality of resistors, and when overcurrent is applied to the FET device, by increasing the resistance value of the resistor connected to the FET device through which the overcurrent flows to block the overcurrent, the gate of the FET switch unit It is possible to provide a field effect transistor protection device and an overcurrent protection system using the same that can stably increase the gate voltage to a normal level.

1 is a graph illustrating a change in threshold voltage of a field effect transistor according to state information of the field effect transistor.
2 is a view schematically showing a field effect transistor protection device 100 according to an embodiment of the present invention.
3 is a schematic diagram of an overcurrent protection system 200 using a field effect transistor protection device according to an embodiment of the present invention.

Hereinafter, preferred examples are provided to aid in understanding the present invention. However, the following examples are merely provided to more easily understand the present invention, and the contents of the present invention are not limited by the examples.

2 is a view schematically showing a field effect transistor protection device 100 according to an embodiment of the present invention, Figure 3 is an overcurrent protection system using a field effect transistor protection device according to an embodiment of the present invention ( 200 is a view schematically showing.

2 and 3, the field effect transistor protection device 100 according to an embodiment of the present invention includes a field effect transistor (FET) switch unit 110 and a resistor unit 120. Can be.

Here, the field effect transistor protection device 100 shown in Figs. 2 and 3 is according to one embodiment, and its components are not limited to the embodiment shown in Figs. 2 and 3, and are added and changed as necessary. Or may be deleted. For example, in the field effect transistor protection device 100 according to the exemplary embodiment of the present invention illustrated in FIGS. 2 and 3, the FET switch 110 may be connected to two FET devices 110-1 to 110-2 in parallel. Although illustrated in a form, three or more FET devices may be connected in parallel or implemented using only one FET device.

First, the FET switch unit 110 is located on an electrical circuit and can control the conduction state of the electrical circuit.

Here, the conduction state means that all components of the electrical circuit are electrically connected to form a closed circuit, whereby an ON state through which current can flow on the electrical circuit and an electrical short between the components on the electrical circuit are opened. By forming a furnace, it means the OFF state which interrupts a current on an electric circuit.

The FET switch unit 110 may include a plurality of FET devices 110-1 and 110-2, and the plurality of FET devices 110-1 and 110-2 may be connected in parallel with each other.

In one embodiment, the plurality of FET devices 110-1 and 110-2 may be P-channel MOSFETs (Metal Oxide Semiconductor Field Effect transistors (MOSFETs)). However, the present invention is not limited thereto.

The FET switch unit 110 may control the conduction state based on a gate signal input from the outside. To this end, the field effect transistor protection device 100 according to an embodiment of the present invention may further include a gate signal output unit (not shown).

When the gate signal output unit receives an output control signal from an external control system, the gate signal output unit outputs a gate signal to gate terminals of the plurality of FET devices 110-1 and 110-2 included in the FET switch unit 110. can do.

The resistor unit 120 may be connected to the drain terminal of the FET switch unit 110 and may adjust the resistance value according to whether or not the FET switch unit 110 is abnormal.

The resistor unit 120 may be connected to have a one-to-one correspondence with the plurality of FET devices 120-1 and 120-2. To this end, the resistor unit 120 may include a plurality of static thermistors PTC, 120-1, and 120-2.

The plurality of PTCs 120-1 and 120-2 may be connected to drain terminals of the plurality of FET devices 110-1 and 110-2, respectively. For example, the first PTC 120-1 may be connected to the drain terminal of the first FET device 110-1, and the second PTC 120-2 may be a drain of the second FET device 120-2. Can be connected to the terminal. However, the present invention is not limited thereto.

The plurality of PTCs 120-1 and 120-2 may adjust resistance values based on state information of the plurality of connected FET devices 110-1 and 110-2, respectively.

Here, the state information means information for diagnosing the states of the plurality of FET devices 110-1 and 110-2. For example, the state information may include information of any one or more of temperature, current, current increase / decrease rate, voltage, and voltage increase / decrease rate of the plurality of FET devices 110-1 and 110-2.

In an exemplary embodiment, the resistor unit 120 may include a plurality of resistors when the rate of decrease of the voltage value of the drain terminal side of the FET switch unit 110 exceeds the reference speed after a gate signal is applied to the FET switch unit 110. The resistance values of the PTCs 120-1 and 120-2 can be increased. For example, although a gate signal is simultaneously applied to the first FET device 110-1 and the second FET device 110-2, the first FET device 110-1 and the second FET device 110-2 are applied. Due to the difference in the characteristics, a difference may occur in the rate at which the gate voltage of each of the first FET device 110-1 and the second FET device 110-2 increases. At this time, when the gate voltage rising speed of the first FET device 110-1 is significantly lower than that of the second FET device 110-1, the drain terminal side resistance value R of the first FET device 110-1 is increased. _-D1 ) is lowered at a high speed, and accordingly, the voltage value V _{D1 at} the drain terminal side is also lowered at a higher speed. That is, since the first FET device 110-1 has a resistance that is relatively smaller than that of the second FET device 110-2, an overcurrent flows due to a current flowing in the first FET device 110-1. As a result, the first FET device 110-1 may be damaged. In this case, the resistor unit 120 compares the speed at which the drain terminal side voltage value V _D1 of the first FET device 110-1 decreases with the reference speed, and when the reference speed exceeds the reference speed, the first FET device 110. The resistance value of the first PTC 120-1 connected to the drain terminal side of −1 may be increased to prevent excessive current from flowing in the first FET device 110-1. However, the present invention is not limited thereto, and the resistor unit 120 compares the resistance value R- _D1 with the reference speed of the first FET device 110-1 to overcome the abnormality of the first FET device 110-1. It can also be diagnosed.

Here, the reference speed means a value which is a reference value for diagnosing abnormality in the voltage value reduction rates of the plurality of FET devices 110-1 and 110-2, and means a plurality of FET devices 110-1 and 110-2. ) May be set differently from each other according to the type and characteristics of

After that, when the gate voltage of the first FET device 110-1 reaches a predetermined value and is stabilized, the drain terminal side resistance value and the voltage value of the first FET device 110-1 may also be kept constant. As a result, the first FET device 110-1 and the second FET device 110-1 are balanced. When the first and second FET devices 110-1 and 110-2 are in equilibrium, the resistor unit 120 may measure the resistance of the first PTC 120-1 connected to the first FET device 110-1. It can be reduced to the value initially set.

Here, the initially set value means a value initially set by the user of the field effect transistor switch protection device 100 according to an embodiment of the present invention. For example, the resistor unit 120 may be set to a value small enough not to affect the current flowing when the FET switch unit 110 is turned on.

In another embodiment, the resistor unit 120 may increase the resistance value when the temperature value of the electrical circuit exceeds the first reference temperature value after the gate signal is applied to the FET switch unit 110.

 Here, the first reference temperature value refers to a value used as a reference for diagnosing abnormality of the temperatures of the plurality of FET devices 110-1 and 110-2.

When an abnormality occurs in the first FET device 110-1 and an overcurrent flows in the first FET device 110-1, the temperature of the first FET device 110-1 is increased. In this case, when the temperature value of the first FET device 110-1 exceeds the first reference temperature value, the resistor unit 120 may be connected to the first PTC 120-1 connected to the first FET device 110-1. The resistance value of can be increased. Thereafter, when the temperature value of the electrical circuit falls below the second reference temperature value, the resistance value of the first PTC 120-1 may be adjusted to an initial set value.

Here, the second reference temperature value means a value serving as a reference for determining whether the temperatures of the plurality of FET elements 110-1 and 110-2 are in a steady state. For example, the first reference temperature value and the second reference temperature value may be set to the same value. However, the present invention is not limited thereto.

In one embodiment, the resistor 120 is based on any one or more of the temperature of the FET switch 110 and the temperature of the wires connecting the components on the electrical circuit, the plurality of FET devices (110-1 and 110). -2)) can diagnose the abnormality.

Although described above with reference to a preferred embodiment of the present invention, those skilled in the art will be variously modified and changed within the scope of the invention without departing from the spirit and scope of the invention described in the claims below I can understand that you can.

10: battery
110: FET switch unit
110-1: first FET device
110-2: second FET device
120: resistance
120-1: First PTC
120-2: second PTC
130: control unit

Claims (7)

A field effect transistor (FET) switch unit located on an electric circuit; And
And a resistor unit connected to the drain terminal of the FET switch unit and adjusting a resistance value according to whether or not the FET switch unit is abnormal.
Field effect transistor protection device.
The method of claim 1,
The FET switch unit includes a plurality of FET elements connected in parallel,
The resistance unit,
And a plurality of static characteristic thermistors (PTCs) respectively connected to drain terminals of the plurality of FET devices so as to correspond one-to-one with the plurality of FET devices.
Field effect transistor protection device.
The method of claim 1,
The resistance unit,
After the gate signal is applied to the FET switch unit, when the rate of decrease of the drain terminal side voltage value of the FET switch unit exceeds a reference speed, the resistance value is increased and the voltage value of the gate terminal reaches a preset value. In this case, characterized in that for adjusting the resistance value to the initial set value,
Field effect transistor protection device.
The method of claim 1,
The resistance unit,
After the gate signal is applied to the FET switch unit, when the temperature value of the electrical circuit exceeds the first reference temperature value, the resistance value is increased, and the temperature value of the electrical circuit falls below the second reference temperature value. In this case, characterized in that for adjusting the resistance value to the initial set value,
Field effect transistor protection device.
A field effect transistor (FET) switch unit located on an electric circuit; And
A field effect transistor protection device comprising a; resistance unit connected to a drain terminal of the FET switch unit; And
And a controller for diagnosing an abnormality of the FET switch unit using at least one of a current value and a voltage value of the FET switch unit, and adjusting a resistance value of the resistor unit based on a diagnosis result.
Overcurrent Protection System.
The method of claim 5,
The control unit,
After the gate signal is applied to the FET switch unit, when the rate of decrease of the drain terminal side voltage value of the FET switch unit exceeds a reference speed, the resistance value of the resistor unit is increased, and the voltage value of the gate terminal is a preset value. When it reaches, characterized in that for adjusting the resistance value of the resistor unit to the initial set value,
Overcurrent Protection System.
The method of claim 5,
The control unit,
If the temperature value of the electrical circuit exceeds the first reference temperature after the gate signal is applied to the FET switch unit, the resistance value of the resistor unit is increased, and the temperature value of the electrical circuit is less than or equal to the second reference temperature value. When falling to, characterized in that for adjusting the resistance value of the resistance portion to the initial set value,
Overcurrent Protection System.

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