JPS63105521A - Drive control method for electrostatic induction type self-extinction element - Google Patents

Abstract

PURPOSE:To widen the stable operating region by applying high speed switching at the normal operating range and turning off the current of the extinction element in the overcurrent state slowly. CONSTITUTION:With a drive signal VS for the extinction element (IGBT) 3 given as an ON-signal, the circuit is brought into the fast leading mode by a Zener diode 12, a capacitor 13, a resistor 14, an operational amplifier 31, a transistor (TR) 6 and a resistor 8. When the drive signal VS is given as an OFF-signal, the rate of change in the gate voltage of the IGBT is devised to be varied depending whether a TR 15 is turned on or off through the use of the electric charge in the capacitor 13. If the IGBT3 reaches an overcurrent and the collector voltage reaches a voltage decided by a Zener diode 32, a TR 24 is turned on and a TR 15 is turned off. When the drive signal VS is zero in this state, the discharge of the capacitor 31 is advanced rapidly up to the voltage of the diode 12 and then slows down, the trailing of the gate voltage of the IGBT slows down and the safe operation region of the IGBT is expanded. Moreover, in case of the normal operation, the gate voltage of the IGBT having a higher rate of rise in the leading is selected and the IGBT is turned off quickly.

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Industrial Application Field) The present invention relates to a yJA motion control method for an electrostatic induction type self-extinguishing element whose drive circuit is improved so that it can be driven safely.

(Prior Art) A device using an electrostatic induction type self-extinguishing element is known as a DC-AC or DC-AC power exchange device. As this electrostatic induction type self-extinguishing element, IGBT (Insu
laed bats bj, polar transi
stor) and FIET.

GE's product name IGOT (Insulated gate)
trans, tstor) are well known, for example “Application of Insulated
Gate Transis tors” (Fac
tory Electronics 1983). Typical GE product number 1) described in the literature in Figure 6! 114 FQl (18A, 400
V) and FRI (18A, 500V), gate voltage VO, collector voltage VC[! and the correlation between the collector current Ic and the collector current Ic. According to FIG. 6, the static induction type self-extinguishing element has a gate voltage of ■. I! It can be seen that in the range where VOB is low, it exhibits constant current characteristics similar to those of a transistor, while as the gate voltage VOB increases, it exhibits a low voltage drop similar to that of a thyristor, indicating that it has characteristics intermediate between a transistor and a thyristor.

Further, FIG. 7 shows the safe operating area (SOA) of the electrostatic induction layer self-extinguishing device (hereinafter referred to as IGBT) shown in FIG. 6, for example, the gate-to-emitter resistance RQI! is 5
In the case of Ω, it is shown that safe operation can always be achieved by limiting the collector current to 20 A or less. However, if you try to turn off a current higher than the rated maximum current, so-called latch-up occurs, and even if the gate voltage van is set to 0, the collector current Ic cannot be reduced to 0, and the current density inside the device increases, causing device deterioration. arise. therefore,
When driving an IGBT, it is necessary to avoid using it beyond its safe operating range.

As is clear from Fig. 7, the emitter resistance R6■ is lk
When set to Ω, the safe operating area (SOA) is even narrower, and the collector current must be used below IOA.In this way, lowering the emitter resistance R ('JE)
Since the gate voltage of the IGBT VOR decreases at a rate determined by the time constant of the gate capacitor and the emitter resistance RaE, the gate voltage VOI! If the fall time of is made faster, the current that can be turned off will decrease. Conversely, to cut off a large current, the gate voltage ■oI! It is presumed that it is effective to make the falling rate of change gradual.

FIG. 8 shows a conventionally used IGBT gate drive circuit. According to this, the collector of the IGBT 3 is connected to the positive pole of a DC power supply 1 via a load 2, the emitter is connected to the negative pole of the DC power supply 1, and the DC The positive terminal of the gate power supply 4, whose negative terminal is commonly connected to the power supply 1, is connected to the collector of the NPN transistor 6 via the resistor 5.
The PN transistor 6 and the PNP transistor 7 are complementary connected, and a drive signal vs is inputted to the common connection point of their bases, and a resistor 8 and a diode 9 connected in parallel are connected to the common connection point of the emitters of the transistors 6 and 7. The gate of IGBT 3 is connected through it.

In this circuit, when the drive signal V3 is turned on, the voltage of the power supply 4 is applied to the transistor 6 and the diode 9.
When the drive signal Vs is turned off, the gate is short-circuited to the emitter of IGBT 3 through resistor 8 and transistor 7, and the gate potential is lowered. The resistor 8 at this time corresponds to RoR in FIG. 7, and the maximum collector current may be limited depending on the magnitude of this resistance value.

(Problem to be solved by the invention) However, in such a drive circuit, the rate of change □ of the gate voltage of the IGBT is fixed, so increasing the rate of change increases the switching speed, but the safe operating area is within the seventh Figure RaI! = 1, it becomes narrower as in the case of Ω. On the other hand, to widen the safe operation area, RQF = 5 and Ω (IG
The rate of change of the gate voltage of the BT can be made gentle, but
There is a problem in that the switching speed decreases and switching loss increases, making it impossible to effectively utilize the characteristics of the IGBT.

The steady operating current of the IGBT is used below IOA in the example shown in Figure 7, but when it increases to 20A and 8 degrees due to a load abnormality or control circuit abnormality, it is possible to cut off the fault current within the safe operating area. If it becomes, the current capacity of IGI3T can be used at once, but with the conventional method, the high speed of IGBT cannot be fully utilized unless the current used is always 58 and when abnormality is used it is less than 10A. .

An object of the present invention is to provide a drive control method for an electrostatic induction layer self-extinguishing element that widens the safe operating range by performing high-speed switching in the normal operating range and gently turning off the IGBT current in an overcurrent state. It is about providing.

[Structure of the invention]

(Means for Solving the Problems) The drive 1 control method of the electrostatic induction layer self-extinguishing element according to the present invention is such that when the 1 drive signal of the electrostatic induction self-extinguishing element is turned on, a fast rising mode is set. In addition, when off, a mode with a fast fall and a mode with a slow fall are provided, and the collector voltage of the n-type induction type self-extinguishing element is detected, and when the collector voltage is low, the mode with a fast fall is selected as is characterized by switching to a mode with a slow fall when the value is high.

(Function) In the present invention, the collector voltage of the IGBT is detected,
If this value is higher than the set value, or if the current flowing through lG13T is detected and this value is higher than the set value.

The IGBT is determined to be in an overcurrent state, and the IGBT is safely protected by selecting a circuit with a low rate of change in the fall of the gate voltage of the IGBT in order to widen the safe operation area of the IGBT. However, during steady operation, the gate voltage of the IGBT is selected to have a higher falling rate of change, so the IGBT is turned off at high speed and can be used with less switching loss.

(Embodiments) The present invention will be described in detail below with reference to embodiments of Ni dynamic control circuits for electrostatic induction self-extinguishing elements shown in FIGS. 1, 4, and 5. In addition, in each drawing, the same components as those in the prior art are given the same numbers, and detailed explanation thereof will be omitted.

FIG. 1 is a circuit diagram showing an embodiment of an IGBT drive control circuit according to the present invention, and as in the case of FIG. The voltage of the Ii source 4 is applied to the gate of the IGRT 3 through complementary connected transistors 6 and 7 and a resistor 8, and the output terminal of the operational amplifier 31 is connected to the common point of the bases of the transistors 6 and 7 through a resistor 10. are connected via.

On the other hand, the Zener diode 23 is connected to the collector of the transistor 24 via the photocoupler light emitting diode 26a, and the emitter is connected to the gate ff1i! , 94, and the base thereof is a Zener diode 32. I through resistor 11
Connect to the GBT 3 collector. Further, a resistor 25 is connected between the base and emitter of the transistor 24.

Furthermore, the drive signal VS is connected to the zener diode 12 and the resistor 9.
are connected in parallel to the non-inverting side of the operational amplifier 31, and the emitter of the transistor 15, the capacitor 13, and the resistor 14 are connected in series to the negative electrode of the gate power supply 4 from the non-inverting side terminal. The collector of the transistor 15 is connected to the input terminal of the drive signal Vs, and the resistor 16 is connected to the base of the transistor 15.
The emitter of the transistor 18 is connected to the negative electrode of the gate power supply 4, and the base of the transistor 18 is connected to the collector of the transistor 24 via a resistor 19 and a diode 22. Gate* from the connection point via resistor 21
Connect to the positive terminal of source 4. Further, a resistor 17 is connected between the base and emitter of the transistor 15, and a resistor 20 is connected between the base and emitter of the transistor 18.

On the other hand, a resistor 27 is connected to the collector of the photocoupler light-receiving transistor 26b, and the photocoupler 26b is pulled up.
The collector voltage of b is input to the AND circuit 28, and the AND circuit output from the control signal Vg and the rising lock circuit 33 is converted to the drive signal 5 by the AND circuit 30 via the latch circuit 29, and the control signal is output. It is configured as follows.

Next, 9i of the electrostatic induction type self-extinguishing φ■ element according to the present invention
! The operation of the Is control method will be explained with reference to the second UA and FIG. First, when the drive input No. 3 becomes an on signal (positive voltage), current flows through the forward direction of the zener diode 12 to the circuit of the capacitor 13 and the resistor 14, and the non-inverting input of the operational amplifier 31 is activated without any time delay. rises, the output of the operational amplifier 31 operates according to the non-inverting input, and the transistor 6
is turned on and an on signal is applied to the gate of IGBT 3 via resistor 8 to turn on IG[IT.

Next, when the drive signal vs changes to zero, that is, an off signal,
The charge on the capacitor 13 is designed so that the rate of change in the voltage of the IGBT changes depending on whether the transistor 15 is on or off.

When the IGRT 3 enters an overcurrent state, the collector voltage rises, and when the voltage determined by the Zener diode 32 becomes -, a current flows to the base of the transistor 24 via the resistor 11, turning on the transistor 24. Since the connection point between the resistor 21 and the resistor 19 is connected to the negative electrode of the gate power source 4 via the diode 22, the base current of the transistor 18 stops flowing, the transistor 18 is turned off, and the transistor 15 is turned off.

When the drive signal Vs becomes zero in this state, the capacitor 13
There is only a circuit that discharges the charge through the resistor 9 and the zener diode 12, so the zener diode 12
The discharge is rapid until the voltage determined by the resistor 9 is reached, and after that, the discharge is discharged with a discharge current determined by the resistor 9, so the discharge becomes gradual, and the fall of the gate voltage of the IGBT becomes gradual.
BT's safe operating area expands.

The purpose of the zener diode 12 is the IG in FIG. 3a.
As is clear from the characteristics of the gate voltage and collector voltage of BT, for example, the gain is low between VAFI 20V and Yap 14, so even if the gate voltage suddenly changes, the safe operation area will not narrow, so the IGBT turn-off In order to shorten the time, a Zener diode 12 is inserted to rapidly reduce the gate voltage.

Furthermore, when the transistor 24 is on, the output of the arithmetic amplifier 31 causes a current to flow through the resistor 1o to the circuit consisting of the zero diode 23 and the photocoupler 26a, and the base potential of the transistor 6.7 becomes zener diode 2
Since the voltage between the base and emitter of transistor 6 and the voltage drop of photocoupler 26a are almost the same, they cancel each other out, and the gate voltage of IGI3T 3 is almost equal to that of the Zener diode. As is clear from FIG. 3(b), the gate voltage of the IGBT changes to the characteristic C according to the collector voltage.
If controlled as shown in Fig. 3(a), the IGBT will have the characteristic C.
It acts to limit the collector current of 3.

When the IGBT 3 is on and no overcurrent is flowing, the collector voltage is low and the transistor 24 is turned off.
A normal voltage is applied to the gate voltage of the IGBT 3. When the transistor 24 is turned off, a current flows into the base of the transistor 18 from the gate power supply 4 through the resistor 21°19, and the transistor 18 is turned on and the transistor 1 is turned on.
5 is in the on state, when the drive signal VS becomes zero, which is the off signal, the capacitor 13 rapidly discharges through the transistor 15 and provides a gate voltage with a high rate of change to the IGBT 3 for high-speed switching. Become.

This will be further explained according to FIG. FIG. 2(a) shows the case during normal operation, and FIG. 2(b) shows the case when an overcurrent flows due to an abnormality on the load side.

In FIG. 2(a), the control signal Vg is input at time t, and the drive signal vs rises from zero. The non-inverting input V of the operational amplifier 31 passes through the Zener diode 12 in the forward direction and charges the capacitor 13, so it rises without delay.
At this point, the IGBT 3 is not turned on at all. At this time, the transistor 24 is turned on, so the base voltage of the transistor 6 is limited to the voltage of the Zener diode 23, and the emitter side voltage of the transistor 6 is V. (
1 has also decreased.

At time t1, the collector voltage ■cE of the IGBT decreases, the transistor 24 turns off, VO becomes a high value, and the IGBT
It acts to further lower the collector voltage of BT.

At time t2, Vg and Vs change to off signals, but the transistor 15 remains on when the transistor 24 is off, and the capacitor 13 is rapidly discharged in the emitter-collector circuit of the transistor 15.

At this time, since there is no delay in V, va quickly becomes zero voltage, and the IGBT performs high-speed switching at time t.
It will be carried out at

This time 1. -13 is the operation delay time of the IGBT 3, which is generally 1 μS or less. Note that the resistor 14 is the transistor 1
5 and Zener diode 12, and can be omitted.

FIG. 2(b) shows a case where an abnormality occurs on the load side, and the photocoupler 26 is activated at time t. -t1, but turns off immediately when normal, the output VaB of the rising lock circuit 33 is '1'' until time t3, and the AND circuit 28 is at V
Since it is configured to operate when both 281 and VAFI become zero, it does not operate in this case.

At time t4, when an abnormality occurs on the load side and the collector current Ic of IGBT3 increases rapidly, the collector voltage V of IGBT
CH increases, transistor 24 turns on and V. (2) to limit the value of c, and at the same time turn off the transistor 15.

Also, since the photocoupler 26b is turned on, Vll3 is “0”.
11 and Vll also becomes 0'' at this time, the AND circuit 28 outputs, and the latch circuit 29 outputs V at time t5 after a delay time due to the noise prevention filter.
29 changes from "1'" to IO'", and the output VS of the AND circuit 10 changes from an on signal to an off signal.

At this time, the l-transistor 15 is in the off state, so the capacitor 13 rapidly drops to the voltage of the zener diode 12, but after that, it is slowly discharged through the circuit of the resistor 9, as shown in v3. A signal VO having a similar waveform is supplied to the gate of the IGBT 3 via the resistor 8. Since the gate voltage changes slowly, the collector current Ic also changes slowly, and VCE also changes slowly, and no surge voltage occurs, so the ROI shown in FIG. 7! The safe operation area expands as the value changes from 1Ω to 5Ω.

In this way, when excessive current flows due to an accident, etc., the gate voltage is lowered to limit the increase in fault current, and at the same time, by making the fall of the gate voltage gradual, the IGBT
It becomes possible to expand the safe operation area of the IGBT and safely protect the IGBT.

In Fig. 1, it is preferable to select the zener voltages of zener diodes I2 and 23 to be approximately the same in order to shorten the non-control time, but zener diode 12 may be a general diode with almost the same effect. and the drive signal V
If the impedance of resistor 3 is made low, basic operation will not be affected even if resistor 14 is omitted.

Next, in another embodiment shown in FIG. 4, compared to FIG. 1, the fall time of Vo is changed by connecting a capacitor ]3 to the feedback circuit of the operational amplifier.

The gate power supply is divided into positive and negative into 48 and 4b, and the drive signal V
s connects the negative ON signal to the inverting input of the operational amplifier 31 via the resistor 9, and outputs the Zener diode 12 ■+11
1 and the inverting input to set the output voltage of Va. A capacitor 13 and a diode 42 are connected in series from the output V31 of the operational amplifier 31, and the capacitor 13 is connected to the output V31.
AT is rapidly charged.

The discharge circuit of the capacitor 13 includes a resistor 40 and a diode 4.
When FET43, which has a circuit that flows through 1 to the inverting input of operational amplifier 31, is on, it conducts FET43 in the opposite direction of diode 42, thereby increasing resistance aor''.
``It is possible to prevent it from flowing.

In an overcurrent state, VCF becomes high and the transistor 24 is turned on, as in Fig. 1, and νB□ is divided by the circuit consisting of the resistor 1o, the resistor 47, and the diode 48 to lower Va, and at the same time, current flows through the resistor 21 and diode 22. Therefore, the base current of the transistor 18 does not flow because the voltage drop of the diode 46 and the voltage drop of the diode 22 cancel each other out, so the transistor 18 is turned off, and since no current flows through the resistor 16, the transistor 15 is turned off, and the voltage drop across the resistor 44゜45 No current flows through FET43 and the gate of FET43 becomes the load voltage.
Since is in the off state, the capacitor 13 is connected in series with the resistor 40 and the diode 41, so that when VRI falls, it performs an integral operation and changes slowly with a constant slope.

On the other hand, during normal operation, the FET 43 remains on and is only connected to the output of the operational amplifier of the capacitor 13 and is not fed back to the input side, so VO changes quickly and the IGBT performs high-speed switching.

Furthermore, another embodiment shown in FIG. 5 is a modification of FIGS. 1 and 4, in which FET42 is replaced by a transistor 50,
It is converted to the collector of a transistor 53 via resistors 51 and 52, and by turning on and off the base of the transistor 53, the falling rate of change of VO is changed.

When the collector current IC of the IGBT 3 is detected by the current detector 55 and an overcurrent is detected by the level detector 56 and the transistor 53 is turned off by the drive circuit 54, the transistor 50
is turned off, and as in FIG. 4, the fall of the gate voltage is made gradual.

Although the circuit for throttling the gate voltage shown in FIG. 4 is omitted in FIG. 5, it functions in substantially the same way by appropriately selecting the gate voltage.

It goes without saying that the operational amplifier is not particularly used and can be replaced with other circuits.

The above explained IGBT, but other static devices such as FET
Needless to say, it can be applied to fi-induced self-extinguishing elements.

〔Effect of the invention〕

As described above, according to the drive control method for an electrostatic induction type self-extinguishing element according to the present invention, the collector voltage and current of the electrostatic induction type self-extinguishing element are detected, and changes in the gate fall are detected in an overcurrent state. Is it quiet by providing a loose circuit?
By expanding the safe operating range of the aM conductive self-extinguishing cord, it is possible to perform high-speed switching during normal conditions and cut off large currents in the event of an accident. Furthermore, by adding a circuit that throttles the gate voltage in the event of an overcurrent, it is possible to further strengthen the effect by suppressing the fault current value.

[Brief explanation of the drawing]

Fig. 1 is a circuit diagram showing the configuration of a drive control device for an electrostatic induction type self-extinguishing element in which the control method of the present invention is implemented, Fig. 2 is a characteristic diagram showing the operation of Fig. 1, and Fig. 31' 3. FIGS. 3(a) and 5(b) show characteristics Jtf showing some of the effects of the present invention, FIGS. 4 and 5 are circuit diagrams showing other embodiments to which the control method of the present invention is applied, and FIG. 7 and 7 are characteristic diagrams showing the characteristics of IGBT, and FIG. 8 is a conventional static f11
FIG. 2 is a circuit diagram showing a drive circuit for an m-conductor self-extinguishing element. 1...DC power supply 2...Load 3...I
GBT 4... Gate power supply 31.
...Operation amplifier 28...AND circuit 29.
...Latch circuit 30...AND curve 33.
・・Start-up lock circuit agent Patent attorney Kensuke Chika (and 1 other person) No. 1
Figure 2 Figure Correa y main/E (VCE) J register voltage (VCE) 〒 3 Figure 4 Figure 8 Figure? 2 Figure 5 This 7 fZ71E (VcEl Figure b) -7 Gore 7 Electric 7E (VCEI Figure 7

Claims (2)

[Claims] (1) When the drive signal of the electrostatic induction type self-extinguishing element is on, there is a fast rising mode, and when it is off, there is a fast falling mode and a slow falling mode, and the collector of the electrostatic induction type self-extinguishing element is Driving an electrostatic induction type self-extinguishing element, characterized in that voltage is detected, and when the collector voltage is low, the fast falling mode is switched to the slow falling mode when the collector voltage is high, the falling mode is switched to the slow falling mode. Control method. (2) When the drive signal of the electrostatic induction type self-extinguishing element is on,
It has a fast rise mode and a slow fall mode when off, and directly or indirectly detects the current flowing through the electrostatic induction self-extinguishing element, and detects when the current exceeds a set value. 2. A method for controlling the drive of an electrostatic induction type self-extinguishing element according to claim 1, characterized in that when this occurs, the mode is switched to a slow falling mode.