JP2657912B2 - Thyristor device - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a thyristor device configured to speed up the time change of the charge / discharge charge of the gate capacitance of a thyristor and to approach a critical damping condition. It is used for power equipment for electric power and large electric power.

In the present invention, what is called a thyristor is an ordinary pn pn four-layer structure SCR, a light trigger thyristor, a thyristor without a so-called gate turn-off function, a gate turn-off thyristor, an embedded gate, including the claims. Turn-off thyristor, MOS gate thyristor,
Thyristors such as single-gate static induction thyristors and double-gate static induction thyristors, as well as bipolar mode MOSFETs or COM (conductivity modulated) FETs
And other devices that perform the same operations as thyristors.

[Problems to be solved by conventional technology and invention]

2. Description of the Related Art Conventionally, several methods have been used for driving a device using a thyristor. For example, (1) a method using a power supply and a switching element (2) a method using a speed-up capacitor (3) a method using an inductance in a gate circuit (4) a method using a pulse transformer in a gate circuit (5) (1)- It is any combination of (4).

The simplest method uses a power supply and switching elements such as bipolar transistors, power MOSFETs, and small thyristors.

FIG. 1A is an example of a thyristor device having a drive circuit including a power supply and a switching element, and FIG. 1B is an equivalent circuit of FIG. 1A.

This is an example in which a gate terminal of a thyristor is connected in series to a power supply E for trigger or quench via a switching element. Because of the simplicity of the gate drive circuit, it is usually most often used in driving (turn on (including turn off)) small and medium power thyristors.

Further, at the time of turn-on and / or turn-off switching, a method using a capacitor for speeding up is also used as a conventional means. In a high-power thyristor, a method using a pulse transformer is proposed because there is no high-current switching element, or a current thyristor of 100 A class or more is used.

Furthermore, there is also a method in which an inductance L is inserted into a gate control circuit and driving is performed using energy stored in the inductance. Inserting an inductance component into the gate circuit is effective in both ON and OFF in terms of driving the thyristor at high speed, but on the other hand, overcurrent flows too much to destroy the thyristor or to drive the thyristor For the thyristor, the parasitic oscillation phenomenon occurs in the gate circuit, and the drive is suppressed for the thyristor.

In addition, the oscillation phenomenon in the gate circuit is caused by the inverter with the bridge configuration using a plurality of thyristors,
When used in converter PWM control or serial / parallel connection, there is also a problem that high frequency noise is generated in the drive circuit of the thyristor, which leads to malfunction of the device itself.

In the method of providing a circuit type in which the switch element and the power supply are connected in series in the drive circuit as described above, the equivalent circuit can be considered as an RC series circuit. As shown in FIG. 1 (c), the voltage waveform at both ends of the capacitor has a RC time constant for charging, so that the drive is slow.

That is, a gate voltage for driving the thyristor is applied only after reaching the point C.

The broken line in the drawing shows the voltage waveform at both ends of the capacitor C in FIG. 1B, and the solid line shows the ideal rising waveform.

As described above, the problem of the method (1) is that a time delay occurs due to the RC time constant. The problem with the method (2) is that, in driving a thyristor of the order of several hundred amperes, the charging time of the speed-up capacitor becomes longer, and the substantial repetitive switching frequency is limited by the charge-discharge time constant of the speed-up capacitor. It is.

Further, in the method using the stored energy of the inductance as in (3) and (4), there is a problem that the parasitic vibration is easily generated. In addition, such a drive circuit has an LC circuit configuration as shown in FIG. 1 (d). In order to drive the thyristor at high speed, a large charge / discharge current of the gate capacitor of the thyristor can be obtained. Therefore, there is also a problem that the thyristor is easily destroyed. In order to switch the thyristor at high speed, the capacity of the gate may be charged and discharged at high speed. That is, it is sufficient that the charge / discharge charge amount to the gate capacitance is changed over time at high speed.

However, in the methods performed so far, each of the methods (1) to (5) has a problem as described above.

[Object of the invention]

An object of the present invention is to provide a thyristor device provided with a gate drive circuit for driving a thyristor at high speed.

More specifically, a thyristor provided with a gate drive circuit for driving the thyristor at high speed by inserting an equivalent input capacitance of the thyristor and an inductance component for resonance into the gate drive circuit to cause a resonance phenomenon (peaking). It is to provide a device.

More specifically, in order to operate the thyristor at high speed, it is necessary to flow a large amount of charge / discharge current at first, and therefore, a damping oscillation corresponding to a half cycle of charge / discharge time is generated in the control circuit. It is an object of the present invention to provide a thyristor device provided with a gate drive circuit. Another object of the present invention is to provide a thyristor device provided with a gate drive circuit, wherein a series resistor is inserted into a gate circuit so that the parasitic oscillation does not exceed several cycles at most.

Still another object of the present invention is to operate the gate drive circuit of the thyristor under conditions close to the critical damping condition so that the thyristor input capacitance C _GK and the resonance L
To provide a thyristor device in which a resistor R is inserted so as to further reduce the phase rotation of the parasitic oscillation to π or 2π. It is still another object of the present invention to provide a thyristor device characterized in that a diode is connected in series with the resistor R to control vibration in only one direction in a gate drive circuit.

[Summary of the Invention]

That is, the thyristor device according to the present invention is a commutation turn-off type SCR, a light trigger thyristor, a gate turn-off thyristor, an embedded gate turn-off thyristor,
Single gate / double gate static induction thyristor, light trigger single gate / double gate static induction thyristor, light trigger / light quench single gate / double gate static induction thyristor, MOS gate thyristor, bipolar mode MOS FET, Insulated bipolar mode transistor (IGB
In a power control device such as T), an input capacitance C of a device to be driven and an inductance L forming a resonance circuit are provided in a gate drive circuit, and charging and discharging of a thyristor gate capacitance under peaking conditions (LC resonance state). This is to speed up the time change of the electric charge. In addition, by inserting a resistance component R that approaches the condition of critical damping (R ² = 4 L / C), damping oscillation is caused, and the parasitic oscillation does not exceed several cycles at most. In this way, the time change of the charge / discharge charge time of the gate capacitance of the thyristor is substantially accelerated by performing the driving. As a matter of course,
It is not necessary to insert a resistor when operating under the condition that the thyristor is driven in the first half cycle even when the parasitic oscillation extends over several cycles. This corresponds to so-called peaking conditions.

In particular, in the case of a thyristor that can be turned off by the gate, the gate drive circuit should be driven not only by the turn-on drive circuit but also by the turn-off drive circuit under conditions close to the peaking condition, under-damping condition, or critical damping condition. Thus, not only high-speed turn-on but also high-speed turn-off can be performed.

[Action]

The operation of the thyristor device according to the present invention will be described with reference to FIG. The capacitor C _GK (1) equivalently represents the input capacitance of a power control device such as a thyristor.

Terminal G (5) represents a gate terminal. Assuming that the drive pulse generating circuit 4 simply comprises a power source E (6) and an ideal switch S (7), it is represented as shown in FIG. 2 (b). The circuit shown in FIG. 2 (b) is a transient phenomenon of the RLC series circuit. To drive the thyristor at high speed, the equivalent capacitance C _GK of the gate terminal G (5) is required.
It is necessary to cause the charge / discharge electric charge q (t) to change with time at a high speed, so that a large amount of charge / discharge current must first flow. In FIG. 2 (b), R such that R ² = 4L / C _GK is satisfied.
And L are critical.
ical)) or critical damping (critical-damping). If the initial charge of the gate terminal G (5) and q (o) = q _O, the amount of charge q (t) and current waveform i (t) is It is expressed as

FIG. 2 (c) shows a waveform of a temporal change of q (t) and i (t) under the condition of the critical damping.

In FIG. 2 (b), when R ² > 4L / C _GK , aperiodic or overdamping (overdamping (o
ver-damping)), and the convergence of q (t) to the stationary term EC _GK is slower than in the case of critical damping. Q (t), i under the condition of overdamping
FIG. 2 (d) shows the waveform of the time change of (t).
here, And FIG. 2 (d) Corresponds to the case of

On the other hand, when R ² <4L / C _GK And then Is obtained. FIG. 2E shows changes in i (t) and q (t) when q _O = 0. As t increases The magnitude of the exponential amplitude decreases at a rate of sine wave vibration, which corresponds to a condition called oscillatory or vibration damping (under-damping).

The main part of the present invention is that the gate drive circuit is configured to approach the condition of critical damping. As is clear from the waveforms of FIGS. 2 (c), (d) and (e), in the case of overdamping, the arrival of the stationary term of q (t) is the slowest. On the other hand, in the case of underdamping, the stationary term of q (t) reaches the stationary term quickly but is oscillating. Originally, in order to operate a power control device such as a thyristor at a high speed, it is important to make the time change of the charge / discharge of the gate faster. Therefore, operating the gate drive circuit under the condition of under-damping is best in terms of high-speed drive. However,
Under the condition of under-damping such that the oscillation phenomenon extends for several cycles or more, an overcurrent flows to the device, resulting in excessive supply despite the fact that it is only necessary to supply or discharge the necessary and sufficient amount of charge at high speed, resulting in an excessive supply time. It leads to increase or destruction of the device. Therefore, it is desirable that the vibration be within several cycles under the condition of the underdamping.

The main part of the present invention is that the oscillation cycle of under-damping is controlled within several cycles so as to approach the condition of critical damping.

Naturally, if the value of the damping resistor R is extremely small, the parasitic oscillation will continue semi-permanently. However, the switching operation of the thyristor is problematic if it is switched on in the first half cycle. May not be. That is, the peaking condition is sufficient for increasing the switching speed of the thyristor. In a case where the thyristor is turned on at a high speed and turned off at a high speed, it is preferable to operate the thyristor near a critical damping condition.

Specifically, under the under-damping condition, the current i _c passing through the gate capacitance, that is, the gate current is determined by the resistance value R of the inductance value L and the gate capacitance of the thyristor.
_Assuming that C _{GK is} the voltage E generated by the gate drive circuit, at time t, , Which is a vibration or a damped vibration.
i max represents the envelope Never exceed. This oscillating current, which is the gate current of the thyristor, is set to a value that does not allow the thyristor to be turned on beyond the time required to keep the thyristor on. That is, the gate current that can turn on the thyristor
i _g , a current i _c flowing through the gate capacitance C _GK , and a time t _on for turning on the thyristor, Must be satisfied under the condition (R / 2L) ² ≦ 1 (LC _GK ) that can realize underdamping from critical.

[Explanation of Example]

FIG. 2A shows an embodiment of the present invention. L, the value of R is chosen Konrashimuru so as R ² 4L / C _GK in terms of critical damping in consideration of the equivalent input capacitance C _GK devices.

FIG. 3 shows another embodiment of the present invention, and FIG.
Of the drive pulse generating circuit 4 is replaced with a power supply E (6) and a switching device (8). As this switching device, an electronic device such as a transistor or a thyristor is used. Assuming an ideal switch having no resistance in the ON state, as described above, R,
The value of L may be selected. However, in practice, the critical resistance of critical damping is considered in consideration of the ON resistance R _ON of the switching device, the wiring inductance Le in the gate circuit, the parasitic capacitance Cp in the gate circuit including the power supply, etc. R and L to be inserted are determined so as to approach the condition.

 FIG. 4 shows another embodiment of the present invention.

From the drive pulse generator 4, when driving an equivalent input capacitance C _GK (1) such as a thyristor, the resistance R (2) and C _GK (1) for damping are used so as to approach critical damping conditions. , And a CR time constant circuit C _C (9) and R _C (10) for speeding up are inserted in series. C _C ×
The time constant of R _C, when the resistance of the input impedance of the device to display the R _GK (22), it is preferably selected to be _{C C × R C = C GK} × R GK.

 FIG. 5 shows still another embodiment of the present invention.

FIG. 5 shows an embodiment in which the GTO (13) is driven. As described above, the turn-on pulse generation circuit 11 and the GTO 13 are used as trigger drive circuits so as to approach the critical damping condition. Input capacitance C
An inductance Ltg (18) for resonance with _GK (15) and a resistance Rtg (19) for damping are inserted. That is, R _tg
² 4L _tg / C Selected near the condition of _GKg . GTO is a thyristor that can be turned off by a gate. In the embodiment shown in FIG. 5, a quench drive circuit further includes a turn-off pulse generation circuit (12) and an input capacitor C of GTO (13).
_Gkg (15), inductance L _qg (17) for resonance and resistance R _qg (16) for damping are inserted. Thus also R _qg ² 4L _qg / C _Gkg conditions near R _qg as quench drive circuit, the value of L _qg is chosen. Reference numeral 20 denotes an anode terminal A, 21 denotes a cathode terminal K, and 14 denotes a gate terminal G.

FIG. 6 shows still another embodiment of the present invention, and corresponds to a case where the electrostatic induction thyristor 31 is driven.

Static induction thyristor 31 is a thyristor which can turn off the gate like the GTO, smaller than the input capacitance to the GTO, since extremely smaller internal gate resistance component r _G, is characterized in that faster switching speed. As a thyristor device provided with a drive circuit that operates under conditions that approach the critical damping condition of the present invention, the drive circuit can be made smaller and lighter than a thyristor device using GTO.

FIG. 6 will be described. In FIG. 6, _Ets (23) and _Eqs
(24) indicates a trigger gate power supply and a quench power supply, respectively. S _t (25) and S _q (26) indicate switches using switching elements. C _Gks (32) indicates an equivalent input capacitance of the electrostatic induction thyristor 31. 33 denotes an anode terminal A and 34 denotes a cathode terminal K. Inductance L _ts (2 for resonance with C _Gks (32) in the trigger drive circuit
7) and the damping resistor R _ts (value of 29), the on-resistance R _on of the switching element 25 _(st), including the Konrashimuru so the condition of critical damping with _{(R ts + R on (st} )) 2 4L It is selected to satisfy the condition of _ts / C _Gks . Similarly, the values of the inductance L _qs (28) for resonance with the C _Gks (32) and the resistance R _qs (30) for damping in the drive circuit for quench include the on-resistance R _{on (sq)} of the switching element 26. are selected to satisfy the condition of critical damping in Konrashimuru so the _{(R qs + R on (sq} )) 2 4L qs / C Gks conditions.

FIG. 7 shows still another embodiment of the present invention. Reference numeral 35 denotes a main thyristor portion of the light trigger thyristor. Reference numeral 36 denotes an auxiliary light trigger thyristor for driving the main thyristor 35 in an auxiliary manner. When the auxiliary light trigger thyristor 36 is turned on by the light trigger signal (hv) (42), a trigger current is supplied from the anode terminal A (40) in a high voltage state to the gate of the main thyristor 35 through the auxiliary light trigger thyristor 36. Is done. At this time, in order to approach the condition of the critical damping of the present invention for driving at a high speed, the equivalent input capacitance C _GKO (39) of the main thyristor 35, the inductance component L _O (37) for resonance, and the resistance for damping are obtained. Minute
R _O (38) is inserted between the gate G of the main thyristor and the cathode portion of the auxiliary light trigger thyristor 36. That is, the on-resistance of the auxiliary light trigger thyristor 36 is selected so as to satisfy When _{R on (op) (R o} + R on (op)) 2 4L O / C GKO.

In FIG. 7, it goes without saying that a light trigger electrostatic induction thyristor may be used instead of the main light trigger thyristor 35 or the auxiliary trigger thyristor 36. Also L _O (3
8), C _C (9) and R _C (10) in the series circuit of R _O (38) for speedup described in the embodiment of FIG.
Of course, a CR time constant circuit consisting of

FIG. 8 shows still another embodiment of the present invention. The present invention relates to a thyristor device having a function of turning off at a gate, such as a GTO or an electrostatic induction thyristor, characterized by including a light-controlled switching element in a gate drive circuit for turning off the thyristor 43. That is, the off-gate power supply E _Gq (45), the electrostatic induction light trigger thyristor (44), the equivalent input capacitance C _GKg of the thyristor 43, the resonance inductance L _gq (46), and the damping resistance R _gq (47). In the off-gate drive circuit, the values of L _gq (46) and R _gq (47) change the on-resistance of the electrostatic induction light trigger thyristor (44) to R _{on (SIThy)}
The taking into account _{(R gq + R on (SIThy} )) is not chosen so as to satisfy the condition of ² 4L _gq / C _GKq.

FIG. 9 shows still another embodiment of the thyristor device of the present invention. In FIG. 9, C _GK (56) indicates the equivalent input capacitance of the power control device to be driven, and the values of the inductance L (54) and the resistance R (55) are selected so as to approach the condition of critical damping. This is the same as in the other embodiments described above. However, in the embodiment shown in FIG. 9, a diode D (53) for controlling the direction of current flow is further inserted in series. By inserting this diode, the current flowing in the negative direction among the current oscillations shown in FIG. 2 (e) is limited under the condition of the underdamping, and therefore, when driving the thyristor device, C is very efficiently used. _GK will be charged.

The insertion of such a diode can be applied not only to a drive circuit for triggering but also to a drive circuit for quench of a power control device having a gate turn-off function such as a GTO or an electrostatic induction thyristor. That is, the quench drive circuit is formed so as to approach the condition of the critical damping of the present invention, and a diode is inserted in a direction in which only the turn-off gate current flows easily. As a result, gate current oscillation during turn-off is suppressed in only one direction, and extremely high-speed turn-off is realized by operating under critical damping conditions or under-damping conditions suppressed only within a few cycles of oscillation. That is.
Inserting a diode that suppresses such current oscillation only in one direction allows only the charging current to flow at the time of turn-on, and allows only the discharge current to flow at the time of turn-off.
This is extremely effective in operation under underdamping conditions close to critical damping.

In the embodiments shown in FIGS. 2 to 9, parasitic factors such as the internal resistance of the pulse generating circuit, the inductance due to the gate electrode, and the gate resistance inside the thyristor are included in the inductance L and the resistance R to be inserted. Was shown. Here, numerical values of more specific embodiments will be described in detail.

The actual equivalent circuit of FIG. 2A is as shown in FIG.

The gate circuit operates as follows when the pulse power source is a constant voltage source.

30 pulse power supply, 31 is due to the internal resistance R _s, 32 inductance L _e is the resistance R _d, 33 for damping to be connected to an external, 34 and 35 of L _g, R _g each gate electrode of the constant voltage source Inductance, gate resistance, 36 and 37 are gate
A capacitance Cgs and resistance R ₂ between the cathode.

The portion surrounded by the dotted line is inside the element. Usually R ₂ 》
If R _o , R _d , R _g , R _o + R _d + R _g = R ₁ , the critical constant k in this circuit is expressed by the following equation.

Since usually R ₂ is very large compared to R ₁ k it can be approximated as follows.

The period T is given by T = 2π (LCa) ^1/2 (6), where a is It is. If R ₂ >> R ₁ , then a = 1 and the period can be approximated as follows.

T = 2π (LC) ^1/2 ... (6) ′ k is obtained from the equations (5) ′ and (6) ′ as follows.

By adjusting the value of the capacitance if it Kimare schematic R ₁ and L between the gate and the source, k = 1 to become critical damping and k can meet the critical damping following than 1. If the cycle determined by L and C is, for example, 1/10 or less of the pulse width, a waveform with a good rise can be obtained.

(Numerical example) k = 1 Assuming that the voltage of the pulse is V _O , the voltage V actually applied to the gate / cathode can be examined with the passage of time as follows.

V = V _O {1− (1 + 2πx) e− ^2πx } (8) where x is a time standardized by a cycle of the LC circuit of t / T.

The damping resistance R was determined as follows from the equation (3).

Capacity 10 ⁴ _p F between the gate and cathode, is L due to the inductance and external inductance of the element 0.1μH
At this time, R ₁ was 6.32Ω. Since the gate resistance of the element and the internal resistance of the constant voltage source can be set to 1Ω or less, for example, if each is 1Ω and the total is 2Ω, then a resistance of 4.32Ω may be connected to the outside, and L connected to the outside is It is unnecessary when the inductance between the element and the package is sufficient.

Rise time t _r of voltage at this time (0.1 V _O time defined to reach 0.9V _O from) than (4) Aforementioned ^{L = 0.1μH, C = 10 4} p F from t _r = 106 _nsec, and the very short. L may be such that k = 1 to reduce the value of R ₁ when large. As the lower limit, if k = 1 in terms of the gate resistance and the internal resistance of the power supply, no external resistance is required. To further reduce the rise time
Should be smaller than 1. When k is smaller than 1, the voltage applied to the gate / cathode is as follows.

k = 0.6 is overshoot when at about 9% rise time t _r = 0.27T, overshoot when k = 0.2 is
53%, rise time is about 0.15T, and critical braking k = 1
Even faster. When k = 0.2, oscillation occurs. The maximum and minimum of the time and the magnitude of the voltage are as follows.

Here, m is an integer.

y _m = 1 − (− 1) ^m e ^−2πKxm (12) If k = 0.2, vibration is reduced in two periods, which is convenient. _{C = 10 p F, L =} k = 0.6 next if the R ₁ and 3.79Ω when 0.1MyuH, rise time of that time It was 53 _nsec . Similarly _{C = 10 p F, L =} 0.1μH
K = 0.2 next if the R ₁ and 1.26Ω at the rise time of that time It was about 30 _nsec . In this case, the gate resistance of the element was about 0.5Ω, the internal resistance of the power supply was about 0.3Ω, and the external resistance was about 1.26−0.5−0.3 = 0.46Ω.

These situations are shown in FIG. In addition, the rise characteristics compared with the conventional device of the present invention which does not consider the braking conditions are shown in FIG.
Shown in the figure. FIG. 14 shows the current flowing through the gate capacitance _CGK .

〔The invention's effect〕

Since the impedance in the control circuit of the thyristor is determined under the condition close to the condition of the critical damping, the thyristor device exhibits the original performance of the thyristor, so that high-speed and high-efficiency switching can be achieved. In addition, overcurrent in the thyristor drive is suppressed and a protection function is provided, so that high-speed and safe drive can be achieved.

[Brief description of the drawings]

FIG. 1 (a) is a diagram showing an example of a driving circuit of a conventional thyristor device, FIG. 1 (b) is an equivalent circuit representation of FIG. 1 (a),
FIG. 1 (c) is a diagram showing a voltage waveform at point G in FIG. 1 (b), and FIG. 1 (d) is a thyristor device in which an inductance is inserted in a gate drive circuit (G indicates a gate terminal of the thyristor). 2 (a) is a diagram showing the most simplified embodiment of the present invention, FIG. 2 (b) is a diagram showing an equivalent expression of FIG. 2 (a), and FIG. Figure (c) shows R ²
= 4L / C _GK , the change of the current i (t) and the charge q (t) (where q (o) = 0), and FIG. 2 (d) shows R ² > 4L.
/ C _GK changes in current i (t) and charge q (t) (where q _O = 0, FIG. 2 (e) shows a change in current i (t) and charge q (t) when R ² <4L / C _GK (where q _O = 0, ), FIG. 3 is an embodiment of the present invention, and FIG.
FIG. 5 is an embodiment of the present invention including a turn-on drive circuit and a turn-off drive circuit, and FIG. 6 is an embodiment of the present invention including a turn-on drive circuit and a turn-off drive circuit for an SI thyristor. FIG. 7 is a diagram showing an embodiment of the present invention, FIG. 7 is a diagram showing an embodiment including a light control element in a drive circuit, FIG. 8 is a diagram showing an embodiment of the present invention including a light control element in a turn-off circuit,
9 shows a thyristor device of the present invention including a diode in a drive circuit, FIG. 10 shows an example of an equivalent circuit in consideration of parasitic capacitance and inductance, and FIG. 11 shows a simplified equivalent circuit of FIG. FIG. 12 shows that the k value is 1, 0.
FIG. 13 is a diagram showing a time change of the voltage waveform at 2, 0.6, FIG. 13 is a diagram comparing the present invention with the conventional example, and FIG. 14 is a current flowing through the gate capacitance C _GK corresponding to FIG. 12, that is, a gate current. FIG.

Claims (2)

(57) [Claims] 1. A thyristor having an anode terminal, a cathode terminal, and a gate terminal, a pulse generation circuit for supplying a pulse to the thyristor, and an inductance and a resistance connected in series between the pulse generation circuit and the gate terminal A gate drive circuit, wherein when the value of the inductance is L, the value of the resistance is R, and the gate capacitance of the thyristor is C _GK , R ² ≦ 4L / C _GK
A thyristor device, wherein the value R of the resistor and the value L of the inductance are determined so as to satisfy the condition, and the gate drive circuit is operated under the condition of critical damping or under damping. 2. The thyristor device according to claim 1, wherein the vibration of the voltage or the current is attenuated within several cycles under the condition of the underdamping.