JPH1155936A - Driving circuit for insulated gate transistor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent decline in efficiency of supplied power without using a Zener diode, by comparing the detected voltage with the reference voltage and controlling the gate voltage of an insulated gate transistor based on the comparison result so that the rate of change in collector current with respect to time may be within a specified range. SOLUTION: A rate of change in collector current Ic with respect to time dIc/dt of an insulated gate bipolar transistor IGBT1 is feedback-controlled based on the resistance ratios of resistors 26c, 26d for dividing voltage and of resistors 27c, 27d for setting reference voltage, thereby controlling the rate of change in collector current Ic with respect to time within a specified range. By setting the rate of change in collector current Ic with respect of time dIc/dt within a specified range, peak voltage ΔV appearing in the wiring inductance 5 at the time of turn on/turn off of the IGBT1 can be suppressed without using such an element as to have a temperature characteristic like a Zener diode.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a drive circuit for an insulated gate transistor, and more particularly, to an application to an inverter circuit, when an insulated gate transistor is turned on and off, a jump voltage generated in an inductance or the like in a wiring. The present invention relates to a drive circuit for an insulated gate transistor in which the above is suppressed.

[0002]

2. Description of the Related Art Many power switching circuits using insulated gate transistors have been proposed. There are several types of insulated gate transistors, for example, an insulated gate bipolar transistor (Insulated) having an insulated gate and operating in a bipolar mode.
Gate Bipolar Transistor (hereinafter referred to as IGBT) or an insulated gate field effect transistor (I) having an insulated gate and operating in a field effect mode.
nsulated Gate Field Effect
t Transistor or Metal Oxi
de Semiconductor Field Ef
Fact Transistor) and the like. Hereinafter, an insulated gate bipolar transistor (hereinafter referred to as IG)
BT) will be described.

FIG. 10 is a diagram showing a chopper circuit to which a gate drive circuit described in Japanese Patent Application Laid-Open No. 5-336732 is applied as an example of a general gate drive circuit.
In the figure, a power supply 2, a diode 3, and a load device 4 connected in parallel to the diode 3 are provided in a closed circuit connecting the emitter terminal and the collector terminal of the IGBT 1. The wiring inductance 5 is shown between the collector terminal of the IGBT 1 and the diode 3.

[0006] A gate drive circuit 6 is connected between the gate and the emitter terminal of the IGBT 1. Hereinafter, the inside of the internal inductance 5a of the emitter terminal of the IGBT 1 is referred to as the emitter terminal 1e, and the outside is referred to as the emitter terminal 1E.

The gate drive circuit 6 includes a gate resistor 7, a gate-on transistor 8, a gate-off transistor 9, gate control circuits 16 and 17, a gate-on power supply 10, and a gate-off power supply 11. As shown in the figure, the gate resistor 7 is connected to the gate terminal of the IGBT 1, and the gate resistor 7 is connected to the emitter terminal and the collector terminal 10 of the gate-on transistor 8 and the gate-off transistor 9, respectively. ing.

Further, a gate-on power supply 10 and a gate-off power supply 11 are provided in a closed path connecting the collector terminal of the gate-on transistor 8 and the emitter terminal of the gate-off transistor 9, and the + terminal of the gate-on power supply 10 is used for the gate-on. The collector terminal of the transistor 8 and the negative terminal of the gate-off power supply 11 are connected to the emitter terminal of the gate-off transistor 9.

A connection point between the gate-on transistor 10 and the gate-off transistor 11 is connected to the IGBT 1
Connected to the emitter terminal 1E. Further, the gate terminals of the gate-on transistor 8 and the gate-off transistor 9 are connected to the gate control circuits 16, 1, respectively.
7 are respectively connected.

FIG. 11 is a circuit diagram showing the gate of the IGBT 1 shown in FIG.
FIG. 5 is a diagram showing a state of a temporal change of an emitter terminal voltage VGE, a collector-emitter terminal voltage VCE, and a collector current Ic. First, the operation when the IGBT 1 is turned on will be described. When a gate-on signal is input from the gate control circuit 16, the gate-on transistor 8 is turned on. As a result, the gate-on power supply 10
1 is supplied with a bias voltage between the gate and the emitter, and the gate-emitter voltage VGE is changed to the threshold voltage Vt.
When h is reached, the IGBT 1 is turned on.

The time from when the gate-on signal is input to when the gate-emitter terminal voltage becomes the threshold voltage Vth and the IGBT 1 is turned on is as follows.
It is determined by the gate resistor 7 and the capacitance CGE between the gate and the emitter terminal of the IGBT 1.

When the voltage VGE between the gate and the emitter terminal of the IGBT 1 reaches the threshold voltage Vth, the IGB
The collector current Ic starts to flow in T1, and the voltage VCE between the collector and the emitter terminal decreases accordingly. At this time,
The gate-emitter terminal voltage VGE of the IGBT 1 passes through a certain region due to the influence of the gate-collector capacitance CCG, and then reaches the gate-emitter terminal capacitance CGE.
And the capacitance CCG between the collector and the gate terminal is charged. When the charging is completed, the voltage VGE between the gate and the emitter terminal of the IGBT 1 reaches the voltage of the power supply 10 for gate-on.

Next, the operation when the IGBT 1 is turned off will be described. When a gate-off signal is input from the gate control circuit 17 and the gate-off transistor 9 is turned on, a reverse bias voltage is supplied from the gate-off power supply 11 between the gate and the emitter terminal of the IGBT 1, and the IGB is turned off.
T1 is turned off.

The operation at this time is the reverse of the operation at the time of turn-on described above, and the gate resistor 7, the gate-emitter capacitance CGE and the collector-gate capacitance CC
When the gate-emitter voltage VGE decreases to the threshold voltage Vth due to the time determined by the discharge time constant determined by G, the collector current Ic of the IGBT 1 is cut off.

It is noted that the jump voltage of the collector voltage when the IGBT 1 is turned off is ΔV, the wiring inductance 5
Let the inductance value of L be a jump voltage ΔV
Is represented by ΔV = L · dIc / dt (Ic is a collector current).

FIG. 12 is a diagram showing an IGBT drive circuit described in Japanese Patent Application Laid-Open No. 7-99429. In the figure, the IGBT 1 and the gate drive circuit 6 are the same as those shown in FIG. 10, but the gate-off power supply 11 (see FIG. 10) of the drive circuit 6 is connected to the emitter terminal 1 of the IGBT 1
e. Further, the emitter terminal 1E of the IGBT 1 is connected to a connection point between the gate terminal 1G of the IGBT 1 and the gate resistor 7 via zener diodes 12a and 12b of opposite polarities connected in series.

In such an IGBT drive circuit,
When the time rate of change of the collector current Ic at the time of turning off the IGBT 1 becomes excessive, the Zener diode 12 having the cathode terminal connected to the emitter terminal 1E side of the IGBT 1
IGBT1 is turned on again by b causing Zener breakdown. As a result, the time rate of change of the collector current Ic is moderated, and the collector voltage jump voltage (FIG. 1)
1 (equivalent to ΔV) is suppressed.

On the other hand, if the time rate of change of the collector current Ic at the time of turning on the IGBT 1 becomes excessive,
The IGBT 1 is turned off when the Zener diode 12a connecting the cathode to the control gate terminal side of T1 causes Zener breakdown. As a result, IGBT1
, The voltage VGE between the gate terminal and the emitter terminal decreases, and the time rate of change of the collector current Ic is reduced.

FIG. 13 is a perspective view schematically showing an outline of a conventional drive circuit for an insulated gate transistor.
As shown in the figure, in the drive circuit of the insulated gate transistor as described above, in order to connect the IGBT 1 and the drive circuit 16, wiring is performed from the gate terminal 1 G of the IGBT 1 to the drive circuit 16.

[0018]

However, even if the Zener diodes 12a and 12b are inserted between the emitter terminal 1E and the gate terminal of the IGBT 1 as described above, the time change rate of the collector current Ic can be suppressed. Since the Zener voltage fluctuates due to the non-linearity and temperature characteristics of the Zener diode, there has been a problem that the time change rate of the collector current Ic increases due to the fluctuation of the Zener voltage.

Further, in order to actually set the time change rate of the collector current Ic finely, it is necessary to connect several types of Zener diodes in series. However, in this case, the number of parts increases, which makes circuit design difficult. There was a problem of becoming.

Since the absolute maximum rating of the gate-emitter terminal voltage VGE of the IGBT 1 is generally ± 20 V, a power supply having an output voltage of 15 V is connected to the gate-on power supply 10.
And by using it as a gate-off power supply 11,
The gate-emitter terminal voltage VGE of the GBT 1 is set to ± 15.
V is set.

However, in the driving circuit as shown in FIG. 10, in order to drive the IGBT 1, it is necessary to supply both the gate-on power supply 10 and the gate-off power supply 11 from the outside. When there are a plurality of power supplies, the configuration of the power supply system becomes more complicated than when there is only one power supply. In particular, the gate drive circuit 6 and the IGB
IPM containing T1 in one package (Intel
When a plurality of power supplies are provided in the LTE (Power Power Module), the handleability is deteriorated and the value as a product is reduced.

In order to solve such a problem,
Various methods have been proposed for obtaining two power supplies from one power supply. For example, as shown in FIG. 14, one input power supply voltage is set to 15 V, and another power supply (+15 V) is generated by the switching transistor 13 and the high-frequency transformer 14.
5V). Further, as shown in FIG. 15, by using the DC-DC converter 15, an output voltage of 30V is changed from a power supply of 30V to a power supply of 15V.
It was also possible to get one.

However, when there is only one power supply, the time from the input of the ON signal to the rise of the collector current Ic of the IGBT 1 and the time from the input of the OFF signal to the start of the decrease of the collector current Ic In order to set the time to the same time as when two power supplies are used, it is necessary to output 15 V as the ON power and the OFF power, respectively. As a result, the output of the power supply voltage is 30
V is required, and there is a problem that the loss of the control circuit increases.

As described above, a method using two power supplies,
Alternatively, in any of the methods for obtaining two power supplies from one power supply, there has been a problem that the degree of freedom of design is limited or efficiency is reduced due to complexity of the circuit.

As described above, in the conventional insulated gate transistor drive circuit (FIG. 13), the IGBT is required to connect the drive circuit to the internal inductance 5a.
Since it is necessary to lay a considerably long distance from 1 to the drive circuit, when this wiring forms a closed loop,
There has been a problem that a malfunction occurs due to the voltage generated by the magnetic flux.

Accordingly, the present invention has been made to solve the above-described problems, and does not use a Zener diode which is a problem in circuit design.
An object of the present invention is to provide a drive circuit for an insulated gate transistor which has solved the reduction in efficiency due to a complicated power supply.

[0027]

An insulated gate transistor according to the present invention is connected to a gate terminal of the insulated gate transistor, and has gate drive means for turning on / off the insulated gate transistor in response to a gate on command or a gate off command. Control means for controlling the driving of the gate drive means based on the gate-on command or gate-off command, current change rate detection means for detecting the time change rate of the collector current of the insulated gate transistor as a voltage, and current change rate detection means Reference voltage detecting means for detecting a voltage as a reference for detecting the detected voltage, comparing means for comparing the detected voltage of the current detecting means with the reference voltage, and a time change rate of the collector current based on a comparison result of the comparing means To control the gate voltage of the insulated gate transistor so that is within a certain range. Comprises a pressure control means, the.

A drive circuit for an insulated gate transistor according to another embodiment of the present invention is connected to a gate terminal of the insulated gate transistor and configured to turn on / off the insulated gate transistor in response to a gate-on command or a gate-off command. A driving unit, a control unit that controls driving of the gate driving unit based on a gate-on command or a gate-off command, and a collector of the insulated gate transistor.
In order to detect the time rate of change of the voltage between the emitter terminals, a voltage change rate detecting means for detecting the voltage between the collector and the emitter terminal, and a voltage as a reference for comparing the detected voltage detected by the voltage change rate detecting means are detected. Reference voltage detecting means,
Comparing means for comparing the detection voltage of the voltage change rate detecting means with the reference voltage; and an insulated gate transistor so that the time change rate of the collector-emitter terminal voltage is within a certain range based on the comparison result of the comparing means. And a gate voltage control means for controlling the gate voltage.

The current change rate detecting means includes a pair of resistors connected in series. The pair of resistors are connected in parallel to an internal inductance of an emitter terminal of the insulated gate transistor, and a connection point between the resistors is connected. It is characterized in that it is connected to the input terminal of the comparing means.

Further, the insulated gate transistor includes a current detecting element for detecting a collector current, the current change rate detecting means includes a pair of resistors connected in series, and the pair of resistors includes the current detecting element. And a connection point thereof is connected to an input terminal of the comparison means.

Further, the voltage change rate detecting means is a capacitor and a resistor provided between a collector and an emitter terminal of the insulated gate transistor.

The reference voltage detecting means includes a pair of resistors connected in series. The pair of resistors is provided between both ends of the power supply, and the connection point is connected to the input terminal of the comparing means. It is characterized by being.

The gate voltage control means includes a constant current drive switch element for driving the gate drive means with a constant current and a constant current setting resistor, and the constant current drive switch element is turned on. Discharging the electric charge between the gate and the emitter terminal of the insulated gate transistor to control the gate voltage of the insulated gate transistor, and the constant current setting resistor to limit the current flowing to the gate driving means. Features.

The power supply further includes a variable power supply for variably controlling the gate terminal voltage. The variable power supply is provided between both ends of a single power supply and connected to an emitter terminal of an insulated gate transistor. It is characterized in that the gate terminal voltage of the insulated gate transistor can be variably controlled based on the command and the detection result of the comparing means.

Further, a shield for magnetic shielding is provided, and the shield is provided between the insulated gate transistor and the drive circuit, and is electrically connected to an emitter terminal of the insulated gate transistor.

[0036]

BEST MODE FOR CARRYING OUT THE INVENTION

Embodiment 1 FIG. FIG. 1 and FIG. 2 are diagrams schematically showing a drive circuit at the time of on / off of an insulated gate transistor according to the first embodiment of the present invention. 1 and 2
The drive circuit shown in FIG. 1 shows the same drive circuit, but shows only the configuration related to the turn-on and turn-off of the IGBT 1 respectively. In the drawing, the drive circuit shown in FIG. Will be described with the same reference numerals.

In FIG. 1, a control circuit 20 arranged between both ends of a power supply is connected to respective gate terminals of a gate-on transistor 8 and a gate-off transistor 9 as gate driving means. The control circuit 20
A signal input terminal 22 for inputting an on / off signal is provided. The function of the control circuit 20 as the control means is the same as that of the conventional gate control circuits 16 and 17 (see FIG. 11).

Reference numeral 25 denotes a gate voltage dividing resistor, 2
Reference numerals 6a and 26b denote voltage-dividing resistors as current change rate detecting means, which are composed of a pair of resistors connected in series. 27 is a reference voltage setting resistor as reference voltage detection means, 28 is an operational amplifier as comparison means, 29
Denotes an npn-type gate voltage dividing transistor. The gate voltage dividing resistor 25 and the gate voltage dividing transistor 29 constitute a gate voltage control means.

The voltage dividing resistors 26a and 26b detect the voltage generated in the internal inductance 5a,
While detecting the time rate of change dIc / dt of the collector current Ic of the IGBT 1 as an insulated gate transistor,
This is for dividing the detection voltage and sending it to the operational amplifier 28. The reference voltage setting resistors 27a and 27b
Is for dividing the power supply voltage and inputting the comparison reference voltage value of the voltage value detected by the voltage dividing resistors 26a and 26b to the operational amplifier 28.

First, the operation when the IGBT 1 is turned on will be described. IGBT1 by such a drive circuit
When an ON signal is input to the signal input terminal 22 during the driving of the transistor, the gate-on transistor 8 is turned on.
As a result, the gate-emitter terminal capacitance CGE of the IGBT 1 is charged through the gate resistor 7 and the IGBT 1 is charged.
The voltage VGE between the gate and the emitter terminal of the BT1 increases. When VGE reaches the threshold voltage Vth,
The IGBT1 is turned on, and the collector current Ic starts to flow between the collector and the emitter terminal of the IGBT1.

When the IGBT 1 is turned on, the collector current I
Due to c, a voltage V represented by V = L · dIc / dt (L is an inductance) is generated in the internal inductance 5a of the emitter terminal. The polarity of the voltage V is such that the side of the emitter terminal 1e of the IGBT 1 having the internal inductance 5a is +
Thus, the emitter terminal 1E side becomes-. The voltage generated in the internal inductance 5a is divided by the voltage dividing resistors 26a and 26b.
And supplied to the operational amplifier 28. The reference voltage divided by the reference voltage setting resistors 27 a and 27 b is also supplied to the operational amplifier 28.

Here, when the detection voltage (negative voltage) of the voltage dividing resistor 26 becomes lower than the reference voltage (negative voltage) of the reference voltage setting resistor 27, an operational amplifier is used to reduce the gate voltage of the IGBT1. The output of the transistor 28 becomes H level, and the gate voltage dividing transistor 29 is turned on. As a result, the gate voltage of the IGBT 1 decreases, and the collector current Ic decreases.
The time change rate dIc / dt of c decreases.

When the gate voltage of the IGBT 1 decreases and the collector current Ic decreases, the detection voltage of the voltage dividing resistor 26 becomes higher than the reference voltage of the reference voltage setting resistor 27. , The output of the operational amplifier 28 becomes L level, and the gate voltage dividing transistor 29 is turned off. As a result, the gate voltage of the IGBT 1 increases, and the collector current Ic increases, so that the time change rate dIc / dt of the collector current Ic increases.

As described above, the feedback control is performed so that the time rate of change of the collector current Ic becomes a value determined by the resistor ratio between the voltage dividing resistors 26a and 26b and the reference voltage setting resistors 27a and 27b. Therefore, the rate of change of the time change rate dIc / dt of the collector current Ic is controlled so as to fall within a certain range.

At this time, if the value of the resistor of the gate resistor 7 is reduced, the time constant is reduced.
Since the gate-emitter voltage VGE of the IGBT 1 reaches the threshold voltage Vth from the input of the ON signal to the threshold voltage Vth, the time until the collector current Ic rises can be set short, so that the time change rate of the collector current Ic increases. Conversely, it is also possible to increase the resistor value of the gate resistor 7 to further reduce the time rate of change of the collector current Ic. Thus, the time rate of change of the collector current Ic can be set.

Next, the operation when the IGBT 1 is turned off will be described with reference to FIG. When an off signal is input to the signal input terminal 22, the gate-on transistor 8 is turned off and the gate-off transistor 9 is turned on. As a result, the electric charge charged in the capacitance CGE between the gate and the emitter terminal through the gate resistor 7 is discharged, so that the voltage VGE between the gate and the emitter terminal is reduced.

After the gate-emitter terminal voltage VGE becomes constant and the collector current Ic decreases and the gate-emitter terminal voltage VGE falls to the threshold voltage Vth, the IGBT 1 is turned off (see FIG. 12). As described above, when the IGBT 1 is turned off, a voltage V represented by V = L · dIc / dt is generated in the internal inductance 5a as the collector current Ic decreases. The polarity of the voltage V is determined by sandwiching the internal inductance 5a.
The emitter terminal 1e side of the IGBT 1 is-, and the emitter terminal 1E side is +.

The voltage generated in the internal inductance 5a is divided by the voltage dividing resistors 26c and 26d and input to the operational amplifier 28. Also, the reference voltage setting resistor 27
The reference voltages divided by c and 27d are also input to the operational amplifier 28. As a result, the voltage (positive voltage) divided by the voltage dividing resistors 26c and 26d is applied to the reference voltage setting resistor 2
When the voltage becomes lower than the reference voltage (positive voltage) divided by 7c and 27d, the output of the operational amplifier 28 becomes H level to increase the gate voltage of the IGBT 1, and the pnp type gate voltage dividing transistor 29a is turned off. You.

When the gate voltage dividing transistor 29 is turned off, the gate-emitter voltage VGE of the IGBT 1 is
Rises. As a result, the time rate of change dIc / dt of the collector current Ic increases, and the detection voltage detected by the resistors 26c and 26d is changed to the reference voltage setting resistor 27.
When the voltage becomes higher than the reference voltage detected by c and 27d, the output of the operational amplifier 28 becomes L level to reduce the gate voltage of the IGBT 1, and the gate voltage dividing transistor 29a is turned on.

When the gate voltage dividing transistor 29a is turned on, a reverse bias of the power supply 11 is supplied between the gate and the emitter terminal of the IGBT1, so that the gate voltage of the IGBT1 decreases. When the gate voltage decreases, the collector current Ic decreases.

As described above, the voltage dividing resistors 26c and 26d
Feedback control is performed on the time change rate dIc / dt of the collector current Ic of the IGBT 1 within a range defined by the resistor ratio between the reference voltage setting resistors 27c and 27d, so that the time change rate of the collector current Ic is within a certain range. Can be controlled to set. Therefore, as described above, the collector current I
By setting the time change rate dIc / dt of c within a certain range, the jump voltage ΔV generated in the wiring inductance 5 at the time of turning on and turning off the IGBT 1 is suppressed without using an element having a temperature characteristic such as a Zener diode. can do.

Embodiment 2 FIG. 3 is a diagram showing a drive circuit of the insulated gate transistor according to the second embodiment of the present invention. In the drawings, the portions corresponding to FIGS. In FIG. 3, 29b is np
An n-type gate voltage dividing transistor, 30 is a constant current setting resistor, and 31a and 31b are constant current transistors. The gate voltage dividing transistor 29b, the constant current setting resistor 30, and the constant current transistors 31a and 31b as constant current driving switch elements constitute a gate voltage control means, and the operational amplifier 28b corresponds to the first embodiment. , But with the polarity reversed.

Here, the operation at the time of turning off the IGBT 1 will be described. When an off signal is input from the signal input terminal 22, the gate-off transistor 9 is turned on, so that the electric charge charged in the gate-emitter terminal capacitance CGE of the IGBT 1 is discharged. As a result, both the gate terminal voltage and the emitter terminal voltage of the IGBT 1 change, and the gate-emitter terminal voltage VGE
Falls to the threshold voltage Vth, the IGBT
Since 1 is turned off, the collector current Ic of the IGBT 1 is cut off.

As described above, after the OFF signal is input, I
The output of the operational amplifier 28 is at the H level until the collector current Ic of the GBT 1 is cut off, and the gate voltage dividing transistor 29b is turned on. At this time, Ic9 = Vbe /
A constant current represented by R30b flows. Here, Vbe is the voltage between the base and emitter terminals of the transistor 31b, and Rbe
30b is a resistor value of the resistor 30b. At this time, the gate voltage dividing transistor 29b is completely turned on, and the voltage between the collector and the emitter terminal can be ignored.

When the collector current Ic of the IGBT 1 is cut off, the internal inductance 5a has V = L に は dIc / d
A voltage V represented by t is generated. When the detection voltage obtained by dividing the voltage V by the voltage dividing resistors 26c and 26d becomes higher than the reference voltage obtained by dividing the power supply voltage by the reference voltage setting resistors 27c and 27d, the output of the operational amplifier 28 becomes L level. , And the gate voltage dividing transistor 29b is turned off.

As a result, a voltage is generated between the collector and the emitter of the gate voltage dividing transistor 29b. Therefore, the collector current Ic of the gate-off transistor 9
9 is Ic9 = (Vbe-Vce) / R30b, so that the constant current value can be reduced.

As the collector current Ic9 of the gate-off transistor 9 decreases, the gate of the IGBT 1
When the change in the voltage VGE between the emitter terminals becomes gentle, I
Time change rate dIc of collector current Ic of GBT1
/ Dt decreases. Accordingly, the voltage (V = L · dIc / dt) generated in the internal inductance 5a decreases, and as a result, the detection voltage of the voltage dividing resistors 26c and 26d becomes lower than the reference voltage of the reference voltage setting resistors 27c and 27d. When the voltage becomes low, the output of the operational amplifier 28b becomes H level, and the gate-off transistor 29b is turned on.

Although the operation at the time of turn-off has been described above, the same feedback control can be performed at the time of turn-on. Therefore, it is possible to set the time change rate dIc / dt of the collector current Ic within a certain range. As a result, when the IGBT 1 is turned on and turned off, the jump voltage ΔV generated in the wiring inductance 5 can be suppressed.

Embodiment 3 FIG. 4 is a diagram schematically showing a drive circuit of the insulated gate transistor according to the third embodiment of the present invention. In the figure, an IGBT 40 as an insulated gate transistor includes a current sensing semiconductor element 40a connected in parallel, and 41 is a reactor thereof. The same components as those in the first and second embodiments and the related art are denoted by the same reference numerals and described.

The current sensing semiconductor element 40a as a current detecting element has an area one thousandth of the area of the main chip of the IGBT 40, and is provided in the IGBT 40 to monitor the collector current Ic of the IGBT 40. ing. Since a current corresponding to the area ratio with respect to the IGBT 40 as the main chip flows through the current sensing semiconductor element 40a, the collector current Ic can be calculated by using this area ratio.

The operation of the IGBT 40 when it is turned off will now be described. When the IGBT 40 is turned off,
The current detected by the current sensing semiconductor element 40a decreases. As a result, a voltage is generated in reactor 41 such that the potential of node 41b is higher than the potential of node 41a. This voltage is divided by a pair of voltage-dividing resistors 26c and 26d connected in series and compared with a reference voltage. As a result, if the voltage detected by the voltage-dividing resistors 26c and 26d is higher than the reference voltage, The output of the operational amplifier 28 is H
Level, and the gate voltage of the IGBT 40 is reduced by turning off the pnp-type gate voltage dividing transistor 29a.

When the gate voltage of the IGBT 40 decreases,
The current value detected by the current sensing semiconductor element 40a decreases, and the time rate of change of the current decreases, so that the detection voltage of the voltage dividing resistors 26c and 26d is reduced by the reference voltage setting resistors 27c and 27d. When the voltage drops below
The output of the operational amplifier 28 is at the L level. As a result, the pnp-type gate voltage dividing transistor 29a is turned on, the gate voltage of the IGBT 40 increases, and the collector current Ic increases. The operation at the time of turning off the IGBT 40 has been described above, but the same control can be performed at the time of turning on the IGBT 40.

As described above, when the IGBT 40 is turned on and turned off, the feedback control is performed, whereby the time change rate dIc / d of the collector current Ic is obtained.
Since t can be set within a certain range set by the resistor ratio between the voltage dividing resistors 26a, 26b and the reference voltage setting resistors 27c, 27d, the wiring inductance 5 is set when the IGBT 40 is turned on and turned off. The generated jump voltage ΔV can be suppressed.

Embodiment 4 FIG. 5 is a diagram schematically showing a drive circuit for an insulated gate transistor according to a fourth embodiment of the present invention. Configurations similar to those of the first to third embodiments and the related art will be described with the same reference numerals. In the figure, a reverse bias supply power supply 23 as a variable power supply disposed between both ends of a power supply has a voltage output terminal IGBT1.
, So that a reverse bias can be supplied between the gate and the emitter terminal.
Further, one drive circuit power supply 24 (positive bias supply power supply) is provided as a single power supply for supplying a gate voltage to the IGBT 1.

The reverse bias supply power supply 23
A reverse bias is supplied between the gate and the emitter terminal based on the control command from. When an ON signal is input to the signal input terminal 22, the gate-on transistor 8 is turned on.
A bias obtained by combining the forward bias supplied between the emitter terminals and the reverse bias supplied from the reverse bias supply power supply 23 is supplied between the gate and the emitter terminal of the IGBT 1. On the other hand, when an off signal is input to the signal input terminal 22, the gate-on transistor 8 is turned off and the gate-off transistor 9 is turned on.
The output voltage of the reverse bias supply power supply 23 is directly supplied between the gate and the emitter terminal.

Next, the operation when driving the IGBT 1 will be described. In the figure, when the ON signal is input to the signal input terminal 22, the output voltage of the drive circuit power supply 24 is 20 V, and the output voltage of the reverse bias supply power supply is -5.
V.

When an ON signal is input to the signal input terminal 22, the gate-on transistor 8 is turned on,
Since the reverse bias supply power supply 23 supplies a reverse bias (−5 V) between the gate and the emitter terminal of the IGBT 1,
The gate-emitter terminal voltage VGE of BT1 is 20-
5 = 15V, and reaches the threshold voltage Vth by the time determined by the time constant determined by the resistor 7 and the capacitance CGE between the gate and the emitter terminal.
1 is turned on.

When an off signal is inputted to the signal input terminal 22, the output voltage of the reverse bias supply power supply 23 becomes -15V
become. At this time, the gate-on transistor 8 is turned off, the gate-off transistor 9 is turned on, and the output voltage (−15 V) of the reverse bias power supply 23 is directly supplied between the gate and the emitter terminal of the IGBT 1.

Accordingly, the gate-emitter terminal voltage VGE of the IGBT 1 decreases toward -15 V, and the voltage of the resistor 7
When the threshold voltage Vth is reached by a time determined by a time constant determined by the capacitance CGE between the gate and the emitter terminal and the capacitance CGE between the collector and the gate terminal, I
GBT1 is turned off.

At this time, the collector current Ic of the IGBT 1 is
When the detected voltage of the voltage dividing resistors 26c and 26d becomes higher than the reference voltage of the reference voltage setting resistors 27c and 27d due to the decrease of the current change rate dIc / dt, the output of the operational amplifier 28 becomes H From level to L level. As a result, the output voltage of the reverse bias supply power supply 23 becomes -5V. Therefore, the voltage between the gate and the emitter terminal of the IGBT 1 decreases toward −5 V, so that the collector current Ic of the IGBT 1 decreases more gradually than before, and the time rate of change decreases.

Further, when the time rate of change of the collector current Ic decreases and the detection voltage of the voltage dividing resistors 26c and 26d becomes lower than the reference voltage of the reference voltage setting resistors 27c and 27d, the output of the operational amplifier 28a becomes L. H from level
Change to level. As a result, the reverse bias power supply 2
The output voltage of No. 3 becomes -15 V, and the above-described operation is repeatedly performed to perform feedback control. In this manner, the time rate of change of collector current Ic of IGBT 1 can be set within a certain range.

In the above description, since the gate-emitter voltage is set so that the operation is the same as that of the prior art (FIG. 11), the capacitance CGE between the gate and emitter terminals is set.
Are equal, the time constant does not change as long as the gate resistor 7 has the same value, and after the signal is input to the signal input terminal 22, I
The time until the GBT 1 operates becomes the same. In addition, since the external input power supply voltage can be reduced (20 V), the loss of the entire drive circuit generated by the control circuit 20 can be reduced, and the circuit can be simply configured, so that the degree of design freedom is increased. It is also possible to expand and improve efficiency.

When the ON signal is inputted to the signal input terminal 22, the output voltage of the reverse bias supply power supply 23 is 2V,
If the output voltage when the OFF signal is input is set to 18 V, the voltage VGE between the gate and the emitter of the IGBT 1 is obtained.
Can be supplied as ± 18 V, and in this case, the time from the input signal to the operation of the IGBT 1 can be reduced. As described above, the setting of the output voltages of the drive circuit power supply 21 and the reverse bias supply power supply 23 is performed by the IGBT.
It can be set freely within the VGE maximum voltage rating of 1.

Embodiment 5 FIG. 7 is a diagram schematically showing a drive circuit of the insulated gate transistor according to the fifth embodiment of the present invention. In the figure, the first embodiment (FIG. 2)
The same parts as those described above are denoted by the same reference numerals and description thereof will be omitted. 50
Is a capacitor, which is connected in series with the resistor 51a and the resistor 26d. Note that the capacitor 50 and the voltage dividing resistors 51a and 51b constitute voltage change rate detecting means.

Next, the operation when the IGBT 1 is turned off will be described. When the off signal is input to the signal input terminal 22, the gate-off transistor 9 is turned on, so that the electric charge charged to the gate-emitter terminal capacitance CGE of the IGBT 1 through the gate resistor 7 is discharged.
The gate-emitter terminal voltage VGE starts to decrease.

When the voltage VGE between the gate and the emitter terminal starts to decrease and passes through a region where the VGE becomes constant (see FIG. 12), the collector current Ic of the IGBT 1 decreases again, and the voltage VGE between the gate and the emitter terminal becomes the threshold voltage. When the voltage reaches Vth, IGBT 1 is turned off, and collector current Ic is cut off. When the collector current Ic is cut off, the voltage VCE between the collector and the emitter terminal of the IGBT 1 increases.

Accordingly, I50 = C ·
A current of dVCE / dt flows. The voltage obtained by dividing the current by the voltage dividing resistors 51a and 51b is input to the operational amplifier 28, and the reference voltage divided by the reference voltage setting resistors 27c and 27d is also input to the operational amplifier 28. As a result, when the detection voltage on the voltage dividing resistors 51a and 51b side is lower than the reference voltage, the output of the operational amplifier 28 becomes H level, and the pnp type gate voltage dividing transistor 29a is turned off.

On the other hand, if the time rate of change dVCE / dt of the voltage between the collector and emitter terminals increases and the current I50 flowing through the capacitor 50 increases, the detection voltage on the voltage dividing resistors 51a and 51b becomes higher than the reference voltage. , The output of the operational amplifier 28 becomes L level, and the gate voltage dividing transistor 29a is turned on. When the gate voltage dividing transistor 29a is turned on, the IGBT 1
Is supplied with the voltage divided by the gate resistor 7 and the gate voltage dividing resistor 25a, and the gate terminal voltage rises.

When the IGBT 1 is turned on again by increasing the gate voltage in this way, the collector voltage decreases. That is, the feedback control is performed at the voltage change rate dVCE / dt set by the resistor ratio of the voltage dividing resistors 51a and 51b and the reference voltage setting resistors 27c and 27d. Is set within a certain range.

Therefore, the current generated by the time change rate dVCE / dt of the voltage between the collector and emitter terminals is divided by the voltage dividing resistors 51a and 51b and the reference voltage setting resistor 27.
Since feedback control can be performed by setting c and 27d, it is possible to suppress a jump voltage ΔV generated in the wiring inductance 5 when the IGBT 1 is turned on and off.

Embodiment 6 FIG. FIG. 8 is a diagram schematically showing a drive circuit for an insulated gate transistor according to a sixth embodiment of the present invention. In the figure, the same components as those shown in FIG. Embodiment 5
Similarly to FIG. 7, the capacitor 50 is connected in series with the resistor 51a and the resistor 51b.

Next, the operation when the IGBT 1 is turned off will be described. When an off signal is input to the signal input terminal 22, the gate-off transistor 9 is turned on, so that the capacitance C between the gate and the emitter terminal of the IGBT 1 is obtained.
When the electric charge charged in the GE is discharged and the voltage VGE between the gate and the emitter terminal reaches the threshold voltage Vth, the IGBT 1 is turned off and the collector current Ic is cut off.

From the input of the OFF signal to the signal input terminal 22 until the collector voltage starts decreasing, the operational amplifier 28 outputs the H level, and the npn-type gate voltage dividing transistor 29b is turned on. ing. At this time, a constant current flows through the gate-off transistor 9.

Next, when the collector voltage VCE of the IGBT 1 rises, a current represented by L · dI5 / dt flows through the capacitor 50. If the voltage generated by this current is divided by the resistors 51a and 51b and becomes higher than the reference voltage obtained by dividing the power supply voltage by the resistors 27c and 27d, the output of the operational amplifier 28b becomes L level.

When the L level is output from the operational amplifier 28b, the gate voltage dividing transistor 29b is turned off. As a result, the collector-emitter terminal of the transistor 29b is cut off, and a voltage VCE is generated between the collector and the emitter terminal. Therefore, the collector current Ic9 of the gate-off transistor 9 is Ic9 = (VBE-VC
E) / R30b, and the collector current Ic9 of the transistor 9 decreases.

As the collector current Ic9 of the gate-off transistor 9 decreases, the gate of the IGBT 1
The change in the voltage VGE between the emitter terminals becomes gentle,
The voltage change rate of the collector-emitter terminal voltage VCE of the BT1 also decreases. Therefore, when the current I50 (= C.dVCE / dt) flowing through the capacitor 50 also decreases and the detection voltage of the voltage dividing resistors 51a and 51b becomes lower than the reference voltage by the reference voltage setting resistors 27c and 27d, the operational amplifier 28b Is at H level, the transistor 29b is turned on again.

As described above, by repeating the feedback control, the time change rate of the collector-emitter terminal voltage VCE of the IGBT 1 can be kept within a certain range, so that the wiring inductance 5 is applied to the IGBT 1 when the IGBT 1 is turned on and off. The generated jump voltage ΔV can be suppressed.

Embodiment 7 FIG. 9 is a perspective view schematically showing an outer shape of a drive circuit for an insulated gate transistor according to a seventh embodiment of the present invention. In the figure, IGBT1
And the drive circuit 70 are separated by a shield plate 71. The shield plate 71 is a shield for magnetic shielding, is disposed so as to cover the upper part of the IGBT 1, and is electrically connected to the emitter terminal 1E of the IGBT 1.

The shield plate 71 has holes 71a, 71b, 71c corresponding to the emitter terminal 1e, the emitter terminal 1E, and the gate terminal 1G of the IGBT 1. Emitter terminal 1e and emitter terminal 1E of IGBT1
The gate terminal 1G is connected to the drive circuit 70 through these holes, and the wiring passes through the upper side of the shield (the side on which the drive circuit is provided with respect to the shield).

As described above, the emitter terminal 1 of the IGBT 1
By providing a shield plate 71 having the same potential as E,
Since the malfunction of the drive circuit due to the magnetic flux generated by the BT1 can be suppressed, the control for setting the time change rate of the collector current Ic of the IGBT1 within a certain range can be reliably performed.

[0091]

According to the insulated gate transistor of the present invention,
Gate drive means connected to the gate terminal of the insulated gate transistor for turning on / off the insulated gate transistor in response to a gate-on command or a gate-off command;
Control means for controlling the driving of the gate drive means based on the gate-on command or gate-off command, current change rate detection means for detecting the time change rate of the collector current of the insulated gate transistor as a voltage, and current change rate detection means Reference voltage detecting means for detecting a voltage as a reference for detecting the detected voltage, comparing means for comparing the detected voltage of the current detecting means with the reference voltage, and a time change rate of the collector current based on a comparison result of the comparing means. And a gate voltage control means for controlling the gate voltage of the insulated gate transistor so that the temperature falls within a certain range. When using insulated gate transistors, turn on and off the wiring It is possible to suppress the jumping voltage generated wardrobe.

A drive circuit for an insulated gate transistor according to another embodiment of the present invention is connected to a gate terminal of the insulated gate transistor and is used to turn on / off the insulated gate transistor in response to a gate-on command or a gate-off command. A driving unit, a control unit that controls driving of the gate driving unit based on a gate-on command or a gate-off command, and a collector of the insulated gate transistor.
In order to detect the time rate of change of the voltage between the emitter terminals, a voltage change rate detecting means for detecting the voltage between the collector and the emitter terminal, and a voltage as a reference for comparing the detected voltage detected by the voltage change rate detecting means are detected. Reference voltage detecting means,
Comparing means for comparing the detection voltage of the voltage change rate detecting means with the reference voltage; and an insulated gate transistor so that the time change rate of the collector-emitter terminal voltage is within a certain range based on the comparison result of the comparing means. And a gate voltage control means for controlling the gate voltage of the insulated gate transistor. Since feedback control can be performed by setting, it is possible to suppress a jump voltage generated in the wiring inductance when the insulated gate transistor is turned on and off.

The current change rate detecting means includes a pair of resistors connected in series. The pair of resistors are connected in parallel to the internal inductance of the emitter terminal of the insulated gate transistor, and the connection point is set at the connection point. Since it is characterized in that it is connected to the input terminal of the comparing means, the current change rate can be arbitrarily set by changing the resistance ratio of the resistor.

Further, the insulated gate transistor includes a current detecting element for detecting a collector current, the current change rate detecting means includes a pair of resistors connected in series, and the pair of resistors includes the current detecting element. Is connected in parallel to the reactor, and the connection point is connected to the input end of the comparison means.If the time change rate of the current flowing through the current detection element is measured, feedback control can be performed. A jump voltage generated in the wiring inductance when the insulated gate transistor is turned on and off can be suppressed.

The voltage change rate detecting means is a capacitor and a resistor provided between the collector and the emitter terminal of the insulated gate transistor, so that the voltage change rate can be measured with a simple configuration. This makes it possible to suppress a jump voltage generated in the wiring inductance when the insulated gate transistor is turned on and off.

The reference voltage detecting means has a pair of resistors connected in series. The pair of resistors is provided between both ends of the power supply, and the connection point is connected to the input end of the comparing means. The reference voltage can be arbitrarily set by changing the resistance ratio of the resistor.

The gate voltage control means includes a constant current driving switch element for driving the gate driving means at a constant current and a constant current setting resistor. The constant current driving switch element is turned on. Discharging the electric charge between the gate and the emitter terminal of the insulated gate transistor to control the gate voltage of the insulated gate transistor, and the constant current setting resistor to limit the current flowing to the gate driving means. With this feature, the resistor for setting the constant current of the transistor and the current rate-of-change detecting means for changing the gate voltage can be relatively easily designed only by changing the setting of the constant current value.

The power supply further includes a variable power supply for variably controlling the gate terminal voltage. The variable power supply is provided between both ends of a single power supply and connected to the emitter terminal of an insulated gate transistor. Since the gate terminal voltage of the insulated gate transistor can be variably controlled based on the command and the detection result of the comparison means, the loss in the drive circuit can be reduced and the efficiency can be improved. Because it can be easily configured, the degree of freedom in design is expanded.

Further, a shield for magnetic shielding is provided, and the shield is provided between the insulated gate transistor and the drive circuit, and is electrically connected to the emitter terminal of the insulated gate transistor. When detecting the generated voltage of the internal inductance of the insulated gate transistor, it is possible to prevent erroneous detection of the current change rate due to a magnetic flux change at the time of switching of the insulated gate transistor.

[Brief description of the drawings]

FIG. 1 is a diagram schematically showing a drive circuit for an insulated gate transistor according to a first embodiment of the present invention;

FIG. 2 is a diagram schematically showing a drive circuit of the insulated gate transistor according to the first embodiment of the present invention;

FIG. 3 is a diagram schematically showing a drive circuit for an insulated gate transistor according to a second embodiment of the present invention;

FIG. 4 is a diagram schematically showing a drive circuit for an insulated gate transistor according to a third embodiment of the present invention;

FIG. 5 schematically shows a drive circuit for an insulated gate transistor according to a fourth embodiment of the present invention.

FIG. 6 is a diagram schematically showing how a gate-emitter terminal voltage of an insulated gate transistor driven by an insulated gate transistor drive circuit according to a fourth embodiment of the present invention changes.

FIG. 7 is a diagram schematically showing a drive circuit for an insulated gate transistor according to a fifth embodiment of the present invention;

FIG. 8 is a diagram schematically showing a drive circuit for an insulated gate transistor according to a sixth embodiment of the present invention.

FIG. 9 is a perspective view schematically showing a drive circuit for an insulated gate transistor according to a seventh embodiment of the present invention.

FIG. 10 is a diagram showing a chopper circuit to which a gate drive circuit described in JP-A-5-336732 is applied as a conventional drive circuit for an insulated gate transistor.

FIG. 11 is a diagram illustrating an operation of an insulated gate transistor by a conventional insulated gate transistor drive circuit.

FIG. 12 is a diagram schematically showing a driving circuit described in JP-A-7-99429 as a conventional driving circuit for an insulated gate transistor.

FIG. 13 is a perspective view schematically showing an outer shape of a conventional drive circuit for an insulated gate transistor.

FIG. 14 is a diagram schematically showing a method for obtaining two power supplies from a single power supply in a conventional insulated gate transistor drive circuit.

FIG. 15 is a diagram schematically showing a method of obtaining two power supplies from a single power supply in a conventional insulated gate transistor drive circuit.

[Explanation of symbols]

REFERENCE SIGNS LIST 1 IGBT (insulated gate transistor), 8 gate-on transistor (gate driving means), 9 gate-off transistor (gate driving means), 20 control circuit (control means), 23 reverse bias supply power supply (variable power supply), 25, 25a gate Voltage dividing resistors (gate voltage control means), 26a, 26b, 26c, 26d Voltage dividing resistors (current change rate detecting means), 27a, 27b, 2
7c, 27d Reference voltage setting resistors (reference voltage detecting means), 28, 28a, 28b Operational amplifiers (comparing means), 29, 29a, 29b Gate voltage dividing transistors (gate voltage control means), 30a, 30b Constant current setting Resistors (gate voltage control means), 31a, 31
b constant current transistor (constant current drive switch element), 40a current sensing semiconductor element (current detection element), 41 reactor, 50 capacitor (voltage change rate detection means), 51a, 51b voltage dividing resistor (voltage change rate) Detection means), 71 shield plate (shield).

Claims (9)

[Claims] 1. A gate driving means connected to a gate terminal of an insulated gate transistor for turning on / off the insulated gate transistor in response to a gate-on command or a gate-off command, and the gate based on a gate-on command or a gate-off command. Control means for controlling the driving of the driving means; current change rate detection means for detecting the time change rate of the collector current of the insulated gate transistor as a voltage; and Reference voltage detecting means for detecting a voltage; comparing means for comparing the detected voltage of the current detecting means with the reference voltage; and a time change rate of the collector current being within a certain range based on a comparison result of the comparing means. Gate voltage control means for controlling a gate voltage of the insulated gate transistor so that The driving circuit of an insulated gate transistor having a. 2. A gate drive means connected to a gate terminal of an insulated gate transistor for turning on / off the insulated gate transistor in response to a gate on command or a gate off command, and the gate based on a gate on command or a gate off command. Control means for controlling driving of the driving means; and a collector for detecting a time change rate of a voltage between a collector and an emitter terminal of the insulated gate transistor.
Voltage change rate detection means for detecting the voltage between the emitter terminals, reference voltage detection means for detecting a voltage as a comparison reference of the detection voltage detected by the voltage change rate detection means, and a detection voltage of the voltage change rate detection means. Comparing means for comparing with the reference voltage; controlling a gate voltage of the insulated gate transistor based on a comparison result of the comparing means such that a time change rate of the voltage between the collector and the emitter terminal falls within a certain range. And a gate voltage control means for driving the insulated gate transistor. 3. The current rate-of-change detecting means includes a pair of resistors connected in series, and the pair of resistors are connected in parallel to an internal inductance of an emitter terminal of the insulated gate transistor, and the connection is established. 2. A point is connected to an input of said comparing means.
4. A driving circuit for an insulated gate transistor according to claim 1. 4. The insulated gate transistor includes a current detecting element for detecting a collector current, the current change rate detecting means includes a pair of resistors connected in series, and the pair of resistors detects the current. 2. The drive circuit for an insulated gate transistor according to claim 1, wherein the drive circuit is connected in parallel to a reactor of the element, and a connection point thereof is connected to an input terminal of the comparison means. 5. The insulated gate transistor driving circuit according to claim 2, wherein said voltage change rate detecting means is a capacitor and a resistor provided between a collector and an emitter terminal of said insulated gate transistor. . 6. The reference voltage detecting means includes a pair of resistors connected in series, the pair of resistors being provided between both ends of a power supply, and having a connection point connected to an input terminal of the comparing means. The drive circuit for an insulated gate transistor according to claim 1, wherein 7. The gate voltage control means includes a constant current drive switch element for driving the gate drive means with a constant current and a constant current setting resistor, and the constant current drive switch element is turned on. Thereby, while discharging the charge charged between the gate and the emitter terminal of the insulated gate transistor to control the gate voltage of the insulated gate transistor, the constant current setting resistor includes:
7. The drive circuit for an insulated gate transistor according to claim 1, wherein a current flowing through said gate drive means is limited. A variable power supply for variably controlling a gate terminal voltage, wherein the variable power supply is provided between both ends of a single power supply and connected to an emitter terminal of the insulated gate transistor; 8. The driving of the insulated gate transistor according to claim 1, wherein the gate terminal voltage of the insulated gate transistor can be variably controlled based on the control command and the detection result of the comparing means. circuit. 9. The semiconductor device according to claim 9, further comprising a shield for magnetic shielding, wherein the shield is provided between the insulated gate transistor and a driving circuit, and is electrically connected to an emitter terminal of the insulated gate transistor. The driving circuit for an insulated gate transistor according to any one of claims 1 to 8, wherein