JPH06209564A - Off-gate drive device for gate drive circuit - Google Patents

Abstract

(57) [Summary] (Modified) [Purpose] Thermal separation of parts that generate a large amount of heat and parts that have a low maximum operating temperature rating, and between the gate and auxiliary cathode terminals of a self-extinguishing element for high power. The off-gate drive of a small and high-performance gate drive circuit that reduces the stray inductance in the connection loop including the gate negative bias power supply capacitor in the gate drive device and the switching element group for on / off control of the gate current Provide a device. [Structure] A printed circuit board is disposed close to an insulating substrate 6 having good thermal conductivity, and a switching element 2 is attached to the insulating substrate.
A capacitor and a terminal block connected to the outside are attached to the printed circuit board.The drain side of the switching element is connected to this gate between the gate and cathode of the self-extinguishing element for high power, and the source of the switching element. Side is connected to the negative side of the capacitor, the positive side of the capacitor is connected to the cathode of the self-extinguishing element for high power, and the radiation fin can be attached to the back side of the insulating substrate if necessary. .

Description

Detailed Description of the Invention

[0001]

The present invention relates to an SI thyristor and a GT.
The present invention relates to a structure of a gate driving device that improves gate driving performance of a high power self-extinguishing type element such as an O thyristor.

[0002]

2. Description of the Related Art Generally, in a gate drive device for a self-extinguishing element for high power, a control command signal is received, timing control of an on / off command and its driving power source, output of gate power and its required gate power source, etc. Will be needed. In a practical gate drive device, generally, a command signal input circuit for turning on and off a self-extinguishing device for high power, a switching circuit for those timing control signals, and a switching device for supplying gate output power for both turn-on and turn-off modes. , And its required driving power supply, etc. are provided on a single printed circuit board, and the timing of the gate signal and its required gate power are supplied to the gate terminal of the self-extinguishing element for high power through a terminal block etc. provided on the printed circuit board. It is used in practice by forming an integral structure for supplying.

FIG. 5 is a perspective view showing a conventional example.
Is a printed circuit board, and 2 is a switching element group such as MOSFET having lead terminals of a gate 2G, a drain 2D and a source 2S, which are attached to the cooling fins 5, respectively. 3 is a capacitor group, 4 is an externally connected terminal 4G, 4
It is a terminal block 4 having K. Next, the electrical configuration of the figure will be described with reference to the circuit diagram shown in FIG. In FIG. 6, 1
Reference numeral 1 is an SI thyristor which is one of self-extinguishing elements for power, 12 is a connecting portion of a gate driving device of an SI thyristor 11, and 2 is an n-channel MOSFET, and a plurality of them are connected in parallel depending on the magnitude of a gate drawing current. The switching element 3 used in the above is a gate negative bias capacitor, and is charged to a predetermined voltage with the polarity shown from the outside of the gate drive device. Reference numeral 13 denotes a loop of the gate of the SI thyristor 11, the lead wire of the auxiliary cathode and the gate terminal (G) in this gate drive circuit, the diode 7a, the switching element (n-channel MOSFET) 2, the capacitor 3, and the auxiliary cathode terminal (K). 3 shows the stray inductance that is a general term for the wirings and the like formed in 1. 7a
Is a reverse current blocking diode for the purpose of preventing current oscillation, 7b is a resistor for a turn-on gate current circuit current limiter, 7c is a p-channel MOSFET switching element, and 8a is an on-gate power source for supplying a turn-on gate current to a power self-extinguishing element. Is a capacitor for use, and is charged to a predetermined voltage by an external power source as shown in the figure. The diode 7
Although there is a case where it is not necessary to provide a in particular because there is little or no possibility of current oscillation, it is omitted in FIG. 5, but when this diode 7a is provided, the switching element
It is attached to the cooling fin 5 or the like and used.

In FIG. 6, a self-extinguishing element for electric power, S
In order to make the I thyristor 11 conductive, the switching element (p channel MO
SFET) 7c is made conductive, and a gate current is made to flow from the gate terminal (G) of the SI thyristor 11 to the auxiliary cathode terminal (K) through the resistor 7b and the stray inductance 13. On the other hand, in order to turn off the SI thyristor 11, the charging voltage of the capacitor 3 is changed to the conduction state of the switching element 2 so that the SI thyristor 1 is turned on.
1 between the auxiliary cathode terminal (K) and the gate terminal (G), and a gate drawing current is drawn from the gate terminal (G) through the diode 7a and the floating inductance 13. Since the switching elements 2 and 7c are operated so that the conduction timings are opposite to each other, the capacitor 8a, the switching element 7c, and the resistor 7 are connected.
A short circuit loop is not formed between the constituent part of b and the constituent parts of the diode 7a, the switching element 2 and the capacitor 3.

Next, the operation waveforms of the respective parts in the turn-off mode of the SI thyristor 11 in FIG. 5, which are most strongly related to the object of the present application, will be described with reference to FIG. 4 described later. In the figure, the waveform S2 is the gate signal input of the switching element 2 with the horizontal axis representing time, and indicates that the SI thyristor 11 is switched from the ON state to the OFF state at time t1. In the figure, Ia and Va of the waveforms shown at the bottom are SI
It is an anode current of the thyristor 11 and an anode-cathode voltage waveform, and Ig is a gate current at the time of turn-off, which is drawn from the gate terminal (G) of the element 11 by the route of the stray inductance 13, the diode 7a, the switching element 2 and the capacitor 3. , Vg are voltage waveforms between the gate terminal (G) and the auxiliary cathode terminal (K).

This waveform Vg is shown in FIG. 6 near time t2.
For the steady state voltage VG of the capacitor 3 in the circuit diagram of
Rate of change of gate current Ig and stray inductance 1
Vg (max.) Of the value obtained by adding the voltage value given by the product of 3
Becomes After that, at time t3, the stray inductance 13 is formed by the equivalent junction capacitance between the gate terminal (G) and the auxiliary cathode terminal (K) of the SI thyristor 11 and the series capacitance between the reverse equivalent junction capacitances of the diode 7a. Due to the series resonance circuit, the absolute value of the gate voltage waveform Vg decreases, and Vg (m
in.). Similarly, at time t4, SI thyristor 1
1 anode to gate terminal (G), diode 7a,
When the main circuit current is extracted through the path of the switching element 2 and the capacitor 3, the charge of the capacitor 3 is discharged by this extraction current. Therefore, the gate negative voltage of the SI thyristor 11 is more negative than the charging voltage steady value VG of the capacitor 3. Bias decreases.

[0007]

The turn-on / off drive power of the SI thyristor is relatively large, and especially during the turn-off operation, the peak value of the gate extraction current is from a fraction of the main current to the main current in some cases. Since the current value is extremely large, the shape of each used component such as the switching element and the driving power source is large, and the gate driving device becomes large because the heat generation is large and the heat radiation fins are involved. Therefore, the switching element group for supplying gate drive power to the high power self-turn-off element and the driving power supply, and the gate of the high power self-turn-off element itself, and one round of the auxiliary cathode formed by each terminal are formed. The loop wiring length becomes longer, the stray inductance contained in those wirings increases, and the reactive power of the gate drive device is increased more than necessary.
When the self-extinguishing element for high power is turned off by the stray inductance, the extraction speed of the gate extraction current is reduced, and the operation delay time of the self-extinguishing element for high power is increased. Also in terms of structure, the switching element 2, the diode 7a, the resistor 7b, the switching element 7
As described above, c and the like are components that generate a relatively large amount of heat and have a high thermal tolerance, such as capacitors 3, 8a, a terminal block connecting the gate terminal G of the SI thyristor and the auxiliary cathode terminal K, and the switching element 2. The gate control signal generator 7c (omitted in the figure, a control signal generator for the gate electrodes of both MOSFETs) generates relatively little heat and has a relatively low thermal tolerance. In addition, since the device has a property that a large heat generation group and a small heat generation group coexist, there is a drawback in that the device is made larger in size to prevent thermal interference.

On the other hand, as the performance of self-extinguishing type elements for high power in recent years has increased, the speed of switching operation has increased. There is also a problem that the performance of the arc-extinguishing element cannot be fully exhibited. That is, in the case of a normally-on device such as a SI thyristor, a serious problem occurs in a device in which the magnitude of the gate negative bias applied to the gate determines the forward blocking voltage of the self-extinguishing device for high power. is there. In particular, the increase in the stray inductance in the loop included in the gate output circuit described above causes a serious negative negative bias, which makes it difficult to secure the forward blocking capability of the self-extinguishing device for high power. It contains various problems.

The present invention was devised in view of the above-mentioned points, and an object thereof is to provide a switching element group, a resistor, etc. which generate a large amount of heat, and an upper limit temperature for use such as control electronic parts and capacitors. Thermal isolation from low-rated components, gate negative bias power supply capacitor in the gate drive device as seen from the gate-auxiliary cathode terminal side of the self-extinguishing element for high power, and gate current on / off An object of the present invention is to provide a small-sized, high-performance off-gate driving device for a gate driving circuit in which a stray inductance in a connection loop including a switching element group for control is reduced.

[0010]

[Means for Solving the Problems] A means for achieving the object is a high thermal conductivity in which a conductive foil plate is fixed via an insulator in an off-gate driving device for a self-extinguishing type element for high power. Place the printed circuit board close to the insulating substrate of
A switching element is attached to the insulating substrate, a capacitor and a terminal block or a coaxial connector to be connected to the outside are attached to the printed circuit board, and a gate-cathode of the self-extinguishing element for high power is attached. The drain side of the switching element is connected to this gate, the source side of the switching element is connected to the negative side of the capacitor, the positive side of the capacitor is connected to the cathode of the self-extinguishing element for high power, and the back side of the insulating substrate. The heat radiation fins can be attached as needed. That is, according to the present invention, the thermal separation between the internal components for the purpose of the above is performed by switching a group of switching elements or resistors that generate a large amount of heat on one surface of an insulating substrate formed of a good heat conductor capable of mounting cooling fins on the opposite surface. Attach equipment etc.,
Electronic components, capacitors, terminal blocks, etc. that generate little heat are arranged on a printed circuit board that is provided in parallel above the insulating substrate. In addition, the reduction of the stray inductance in the connection loop can be achieved by connecting the electrode lead terminals of the switching element group itself directly to the printed circuit board arranged in close proximity such that the switching element group is sandwiched between them for the gate negative bias power supply. This is achieved by reducing stray inductance in a connection loop including a capacitor and a switching element group for ON / OFF control of gate current. Here, when the gate extraction current is large and the heat generation is large, if a radiation fin is attached to the back side of the insulating substrate to radiate heat, it can be used as a gate drive for a higher power element.

[0011]

The heat generated in the switching element group for driving the gate on / off is efficiently transferred to the outside of the gate driving device through the insulating substrate formed of a good heat conductor by a cooling fin or the like in accordance with the heat generated in the switching element. The heat is dissipated well. On the printed circuit board placed above this switching element group,
The capacitor for the gate negative bias power source and the gate connection terminal block of the power self-turn-off device for powering the gate to be driven are closely connected, and also connected to the switching device at the shortest distance. Therefore, the number of interlinkage magnetic fluxes in the wiring loop through which the gate turn-off current flows is minimized, and the stray inductance of the wiring loop seen from between the gate and the auxiliary cathode of the self-extinguishing type power element is small,
The voltage drop of the transient voltage due to the inductance and the gate turn-off current is suppressed to a minimum, and the decrease in the off-gate negative bias applied to the gate of the power self-turn-off device is small, so the rate of change of the gate extraction current can be increased.
Mainly, the storage time of the self-turn-off type element for electric power can be shortened, so that it can be turned off at high speed. Further, since the inductance is small, the rise of the on-gate current at the time of turn-on is large, the delay time is shortened and the turn-on time is also shortened, so that the operating speed of the self-extinguishing element for electric power can be increased. An embodiment of the present invention will be described in detail below with reference to the drawings.

[0012]

1 is a perspective view of a printed circuit board portion showing one embodiment of the present invention, FIG. 2 is a perspective view of an insulating substrate portion showing one embodiment of the present invention, and FIG. 3 is another embodiment of the present invention. Is a perspective view of the printed circuit board portion, and FIG. 4 is a characteristic diagram. In FIG. 1, 1
Is provided with through holes 1a for inserting the electrode lead terminals of the switching elements for extracting the gate turn-off current of the self-extinguishing element for power, capacitor group 3 for the gate negative bias power supply, A terminal block 4 having a gate terminal connecting portion 4G and an auxiliary cathode terminal connecting portion 4K of the arc-extinguishing element, and an electronic component group 8 for gate control of the switching element group which generates less heat.
Are implemented respectively.

In FIG. 2, the insulating substrate 6 having good thermal conductivity is provided with 6
The conductive foil plate of a is fixed, the switching element group 2 is used as a MOSFET, and other heat-generating component groups 7 such as resistors are mounted. The electrode lead terminals 2G, 2D, 2S (corresponding to the gate, drain, and source electrodes of MOSFET, respectively) of the switching element group 2 itself are bent and inserted into the printed circuit board 1a. The conductive foil plate 6a is arbitrarily separated so that heat can be radiated from the lower portion of the insulating substrate 6 having good thermal conductivity while electrically insulating each other.

Therefore, with the above configuration, the switching element group 2 which generates a large amount of heat and the other heat generating component group 7 such as resistors.
Since the capacitor group 3, the terminal block 4, and the electronic part group 8 for gate control which generate a small amount of heat are separated from each other, thermal interference with each other hardly occurs, and the mutual positional relationships are very close to each other. The above-mentioned stray inductance can be minimized and a sufficient gate negative bias can be secured when the SI thyristor 11 is turned off. 1 and 2, the means for fixing the printed circuit board 1 and the insulating substrate 6 having good thermal conductivity to each other is not shown in the drawing, but they may be connected to each other by columns or integrally fixed to each other by molding. It goes without saying that it can be configured by doing so.

In FIG. 3, the terminal block 4 of FIG. 1 is replaced with a coaxial connector (reception port) 10, and the gate negative bias capacitor group 3 is replaced with a chip type capacitor group 9 having the same function. Here, 10G and 10K indicate the parts for making electrical connection with the coaxial connector (plug side) connected to the gate terminal and auxiliary cathode terminal of the self-extinguishing element for electric power, respectively. Although the same effect can be expected even when the capacitor group 9 is of the same type as the capacitor group 3, the purpose is to contribute to reduction of stray inductance by adopting the type of capacitor having a small outer shape. In this embodiment, the terminals 4G and 4K of the terminal block 4 are connected to the above-mentioned FIG.
Further, since the stray inductance existing between the wiring pattern of the printed board 1 and the wiring pattern is reduced, the effect of the present invention is further enhanced.

[0016]

As described above, according to the present invention, the gate drive device of the present invention is mounted on and mounted on different substrates, the components that generate a large amount of heat and the components that have a low allowable temperature. By placing both substrates close to each other without causing interference, it is possible to minimize the transient decrease in gate negative bias applied between the gate terminal and auxiliary cathode of the power self-turn-off device for safe operation. There is an advantage that the area is wide. Along with this, the gate extraction current can be increased in speed, and the high-speed performance of the power self-extinguishing element can be fully exerted.

[0017]

[Brief description of drawings]

FIG. 1 is a perspective view of a printed circuit board showing an embodiment of the present invention.

FIG. 2 is a perspective view of an insulating substrate showing an embodiment of the present invention.

FIG. 3 is a perspective view of a printed circuit board showing another embodiment of the present invention.

FIG. 4 is a characteristic diagram thereof.

FIG. 5 is a perspective view showing a conventional example.

FIG. 6 is a gate drive circuit diagram.

[0018]

[Explanation of symbols]

 1 Printed Circuit Board 2 Switching Element (MOSFET) 3 Capacitor 4 Terminal Block 5 Cooling Fin 6 Insulating Board with Good Thermal Conductivity 7 Resistor and Other Heating Parts Group 8 Gate Control Electronic Parts Group 9 Capacitor (Chip Type) 10 Coaxial Connector 11 SI thyristor 12 Connection part of gate drive device of SI thyristor 13 Stray inductance

Claims (1)

[Claims] 1. In an off-gate driving device for a self-extinguishing element for high power, a printed circuit board is disposed in close proximity to an insulating substrate having good heat conductivity, to which a conductive foil plate is fixed via an insulator, A switching element is attached to the insulating substrate, a capacitor and a terminal block or a coaxial connector to be connected to the outside are attached to the printed circuit board, and between the gate and cathode of the self-extinguishing element for high power, Connect the drain side of the switching element to the gate, connect the source side of the switching element to the negative side of the capacitor, connect the positive side of the capacitor to the cathode of the self-extinguishing element for high power, and further to the back side of the insulating substrate. An off-gate driving device for a gate driving circuit, wherein a radiation fin can be attached if necessary.