JPH02114821A - Protection of snubber energy regenerative circuit - Google Patents

Abstract

PURPOSE:To protect a self-extinguish element from breakdown by detecting overcurrent flowing through a snubber energy circuit then interrupting conducting paths of the self-extinguish element and a rectifying element having a control electrode and feeding snubber energy to a shortcircuit. CONSTITUTION:Overcurrent flowing through snubber energy circuits 12a-e, 15a-e are detected by means of a comparator 19 through a current transformer 29 and a rectifier 18. GTOs 12, 15 are turned OFF through gates 27, 28 while thyristors 12e, 15e are turned OFF through AND gates 26, 25. The GTOs 12, 15 can be protected from breakdown by feeding snubber energy to shortcircuits 10, 11.

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Industrial Application Field) The present invention relates to a method for protecting a snubber energy regeneration circuit of an inverter device using self-extinguishing elements (eg, GTO).

(Prior art) Conventionally, as a three-phase inverter device using GTO,
There is a configuration as shown in FIG.

Here, in order to simplify the explanation of the operation of the conventional example, a 180° energization inverter device having a three-phase bridge one-stage six-phase configuration will be described as an example. In Fig. 7, 1 is the input transformer 2
A rectifier 3 converts the AC power output inputted through the rectifier 1 into DC, and 3 is an inverter consisting of a bridge circuit composed of a GTO and a diode that converts the DC output from the rectifier 1 into AC. The output is supplied to a load (not shown) via an output transformer 4. 5 is a DC reactor provided on one DC line on the output side of the rectifier 1, and 6 is an accelerator provided on one DC line on the input side of the inverter 3. This suppresses the current rise rate.

7a and 7b are DC filter capacitors provided in series between one DC line and the other DC line connecting the reactors 5 and 6, and the series circuit of these DC filter capacitors 7a and 7b further includes A parallel circuit of a diode 8 and a reactor 9 is connected. This parallel circuit of the diode 8 and the reactor 9 suppresses the short-circuit current that flows when a DC short circuit occurs due to a failure of the inverter 3 composed of the GTO and the diode. Moreover, an axle 10 and a thyristor 11 are provided in series between one DC line and the other DC line connecting the reactors 5 and 6, and these constitute a short circuit.

By the way, in the inverter device configured as described above, various snubber energy regeneration circuits have been studied and devised for the purpose of reducing the loss of the snubber circuit of the GTO that constitutes the inverter 3 and increasing the efficiency of the device. ing.

Figure 8 shows an example of the circuit configuration of a three-phase inverter device equipped with a snubber energy regeneration circuit that regenerates snubber energy to the DC smoothing filter circuit of the main circuit. (t) and its explanation will be omitted. In FIG. 8, 12 to 7 are GTo constituting the inverter 3, 12a to 1.7a are feedback diodes, 12b to 17b are snubber capacitors,
12c to 17c are snubber diodes, 12d to 17d are snubber energy regeneration reactors, 12e to 1.7 e
is a control pole side rectifying element for snubber energy regeneration (hereinafter referred to as Cyrisk).

FIG. 9 is a time chart showing the operation of the inverter circuit with snubber energy regeneration circuit shown in FIG. 8. In FIG. 9, (a) to (f) are GTO12, 17, and 13, respectively.
, 1, 5, 14, and 16, and (g) to (1) indicate gate signals of auxiliary thyristors 12e to 16e. For example, the U-phase snubber energy regeneration circuit operates in mode (I
).

(II). That is, in mode (I), the auxiliary thyristor 12e is fired at time to, and the energy of the snubber capacitor 12b is increased to the accelerator 6, the filter capacitor 7a, and the reactor 12d.

It is regenerated via the auxiliary thyristor 12e. When the charge in the snubber capacitor 12b is discharged and the voltage becomes zero or slightly reversed, the feedback diode 12a is turned on at time t1, and the mode shifts to mode (II). In mode (n), the snubber energy transferred to the beam axle 6 circulates through the DC filter capacitor 7a, the reactor 12d, the auxiliary thyristor 12e, the snubber diode 12c, and the diode 12a, and is transferred until it is attenuated, and the snubber energy is absorbed. .

(Problem to be Solved by the Invention) However, in an inverter device equipped with such a snubber energy regeneration circuit, if an abnormality occurs in the snubber energy regeneration circuit, an overcurrent exceeding the rated turn-off current flows, causing the GTO element to There was a problem of failure in turn-off and damage.

SUMMARY OF THE INVENTION An object of the present invention is to provide a method for protecting a snubber energy regeneration circuit, which detects an overcurrent flowing due to an abnormality in the snubber energy regeneration circuit and stops protection before the GTO elements forming an inverter circuit are damaged. .

[Structure of the Invention] (Means for Solving the Problems) In order to achieve the above object, the present invention regenerates the snubber energy in the snubber circuit of the self-arc-extinguishing elements constituting the inverter circuit to the main circuit of the inverter. In the snubber energy regeneration circuit, when an overcurrent flowing during an abnormality in the snubber energy regeneration circuit is detected, the gate of the self-extinguishing element of the inverter circuit is blocked, and at the same time, the gate of the rectifier element with control pole of the snubber energy circuit is blocked. At the same time as blocking the inverter, a rectifying element with a short-circuit control pole provided in the main circuit of the inverter is ignited.

(Function) In the method for protecting a snubber energy regeneration circuit according to the present invention, when an overcurrent flowing in the snubber energy regeneration circuit is detected, the gate of the self-extinguishing element is blocked and the snubber energy regeneration circuit is simultaneously blocked. The gate of the rectifier with a control pole in the regenerative circuit is blocked and its energizing path is cut off, and the snapper energy is a short circuit formed when the rectifier with a control pole for short circuit provided in the main circuit of the inverter is ignited. Since the current flows through the circuit, it is possible to prevent damage to the self-extinguishing elements that constitute the inverter.

(Example) An embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 shows an example of a circuit configuration for explaining a method of protecting a snubber energy regeneration circuit in the event of an abnormality according to the present invention.
Here, since all three phases (U phase, ■ phase, and X phase) of the inverter circuit have the same configuration, the ■ phase is shown as a representative. Note that the same or corresponding parts as in FIG. 8 are given the same reference numerals, and the explanation thereof will be omitted.

In Fig. 1, 29 is a current transformer installed in the electrical path connecting the snubber energy regeneration circuit and the DC filter capacitors 7a and 7b provided in the main circuit, and this current transformer 29 detects the snubber energy regeneration current. It is something to do. 18 is a rectifier that converts the alternating current Vo corresponding to the snubber energy regeneration current detected by the current transformer 29 into a direct current voltage signal V1. ] 9 is a comparison circuit that compares the DC voltage signal V1 output from the rectifier 18 with a preset reference value, and outputs a signal FLT when 1 exceeds the reference value. 20 is an OR circuit to which the signal FLT output from one comparison circuit and the ignition signal S1 of the thyristor 1 which constitutes a short circuit provided in the main circuit are input;
Thyristor 1] is fired with an output signal of 0.

21 to 26 are AND circuits, one input terminal of the AND circuit 21 receives the ON gate signal 82ON of the GTOl2, one input terminal of the AND circuit 22 receives the OFF gate signal 52or"p of the GTOl2, and the AND circuit 23
On-gate signal 33O of GTOl5 is connected to one input terminal of
N is input, and an off-gate signal 33OFF of the GTOl5 is input to one input terminal of the AND circuit 24. Furthermore, a thyristor 15 is connected to one input terminal of the AND circuit 25.
The on-gate signal of thyristor 1.2e is inputted manually, and the on-gate signal of thyristor 1.2e is inputted to one input terminal of the AND circuit 26. A signal FLT is output from the comparator circuit 19 to the other input terminal of each of these AND circuits 21 to 26.
is added, its output is blocked. 27. 28 is a GTO gate circuit. When a gate-on signal is input from the AND circuit 21, the gate circuit 27 applies a gate-on pulse to the gate of GTOl2, and when a gate-off signal is input from the AND circuit 22, it outputs a gate-on pulse to the gate of GTO12.
The gate circuit 28 outputs a gate off pulse to the gate of GTOl5 when a gate on signal is input from the AND circuit 23, and outputs a gate pulse to the gate of GTOl5 when a gate off signal is input from the AND circuit 24.
This outputs a gate-off pulse to the gate No.5.

Next, the operation of the circuit configured as described above will be explained.

FIG. 2 is a time chart for explaining the operation of FIG. 1, and FIG. 3 is a representative diagram of the snubber energy regeneration circuit of GTOl 2. Here, Fig. 2(a) shows the GTO
On-gate pulse and off-gate pulse of l2, (b) is the gate pulse of thyristor 12e, (C) is the on-gate pulse and off-gate pulse of GTO15, and (d) is the gate pulse of thyristor 15e. (e) is the current of the steering wheel 12d during normal operation.

Now, focusing on a failure when the thyristor 12e is short-circuited, the time point at which overcurrent is detected differs depending on when the failure occurs. For example, Fig. 2 (f), (g)
The case shown by is a case in which the thyristor 12e is short-circuited while the GTO is off. Also, Figure 2 (h)
, (i) is a case where the thyristor 12e is short-circuited while the GTOl5 is on. In either case, an overcurrent flows through a closed loop circuit as shown in FIG. That is, the reactor 12d, thyristor 12e, snubber diode 12c, GTOl5 . Reactor 9. An overcurrent flows in the loop of the negative terminal of the capacitor 7b. ] 0, the cases shown in Fig. 2 (f) and (g) are tF1
At this point, thyristor 12e short-circuited and then GTO15
Until the time t122 when is turned on, the positive electrode of the capacitor 7a,
Reactor 6, capacitor 12b Reactor 12d
, a resonant current continues to flow in the closed loop of the negative electrode of the capacitor 7a, and then an overcurrent flows through the closed loop as shown by the arrow in FIG. In addition, in the case shown in FIGS. 2(h) and (i), at the same time as the thyristor 12e is short-circuited at time tpB, an overcurrent flows through a closed loop as shown by the arrow in FIG. 3. Here, in FIG. 2, OC is the comparison circuit 19
This is the overcurrent detection level set to .

In both cases, when an overcurrent flows in a closed loop as shown in FIG. 3, this overcurrent is detected by the current transformer 29 and further inputted by the rectifier 18 to the comparator circuit 19 as a DC voltage signal v1.

This comparison circuit 19 compares the DC voltage signal v1 with the overcurrent detection level, and when the DC voltage signal v1 exceeds the overcurrent detection level OC, the output signal FLT is sent via the OR circuit 20 to the thyristor 9 constituting the short circuit. added to the gate,
The thyristor 9 is fired. At the same time, the output signal FLT of the comparison circuit 19 causes the output S2 of the AND circuits 21 to 26 to be
A.

Since S2B, S3A, S3B, S, 1G, and S5G are blocked, each GTO12 is on-gate.

The off gate, the on gate of the GTO 15, the off gate, and the thyristors 12e and 15e are gate blocked.

Therefore, when a current flows through a short circuit provided in the main circuit or made up of the accelerator 5 and the thyristor 11, a protective interlocking operation is performed that reduces the DC voltage in a short time and stops the operation of the inverter circuit. Become.

As described above, according to this embodiment, even if an abnormality occurs in the snubber energy regeneration circuit, the overcurrent flowing at that time is detected and the short circuit is activated, and the operation of the inverter circuit is stopped by the protection interlocking operation. The element will not be destroyed, and serious accidents can be prevented. (1) Although not described in the above embodiment, by providing a display means for displaying an abnormality at the time of a failure, it is possible to facilitate investigation of the cause of the accident and shorten the period for stopping the apparatus.

Next, other embodiments of the present invention will be described.

FIG. 4 shows another embodiment of the present invention, and the same parts and equivalent parts as in FIG. 1 are the same. ] and the explanation thereof will be omitted. In this embodiment, DC filter capacitors 7a and 7 are provided in the snubber energy regeneration circuit and the main circuit.
A fuse 31 and a trigger fuse 32, which are blown by an overcurrent flowing in the event of an abnormality in the snubber energy regeneration circuit, are provided in parallel in the electrical path connecting the snubber energy regeneration circuit to the fuse 31, and a detection signal obtained through the trigger contact when the fuse blows is inputted to the abnormality detection circuit 30. This is what I did. The gate signal block circuit configuration after the abnormality detection circuit 30 is the same as that in FIG. 1, so it is omitted here.

Therefore, even with such a configuration, an abnormality in the snubber energy regeneration circuit can be detected, and the same protective interlocking operation as in the embodiment described above can be performed.

FIG. 5 further shows another embodiment of the present invention.
The same or equivalent parts as those in the figures are given the same reference numerals, and the explanation thereof will be omitted. Further, FIG. 6 is a time chart for explaining the operation of FIG. 5. In this embodiment, an example of the main circuit configuration will be described in which the diode 8 and reactor 11 shown in FIG. 1 are not installed.

In FIG. 5, the snubber energy regeneration current detection signal (2) output from the rectifier circuit 18 is applied to a waveform shaping circuit 33 and shaped into a square wave signal of "1" or "0". FIG. 6(i) shows this waveform, and the signal v1 becomes a periodically continuous square wave pulse signal during normal operation. In addition, the illustrated monostable multi-circuit 30.35 is the auxiliary thyristor 1.
It is triggered by the rise of the gate signal S4 of the thyristor 5e and the gate signal S5 of the auxiliary thyristor 12e, and a constant is set to obtain a pulse with a longer pulse width than the snubber energy regeneration current detection signal v2 during normal operation. . Therefore, under normal conditions, the snubber energy regeneration current detection signal V2 is masked by the pulse signal V3. Outputs V4.

Figure 6 (h).

(j) shows each of these pulse signals.

In this way, the pulse signal V3. obtained from the monostable multicircuit 30.35. V4 is applied to the AND circuit 34 together with the pulse signal V2 output from the waveform shaping circuit 33. Since this AND circuit 34 takes the logical product of these signals, the detection signal V2 in the normal state is masked by the pulse signals v3 and ■4, and no output signal is sent out. However, in the case of an abnormality, a pulse signal is obtained from the AND circuit 34. , which is configured to be applied to the flip-flop 32 as a set signal v5.

Therefore, this flip-flop 32 is connected to the AND circuit 3
4, the set output is used as a failure signal FLT to stop the gate of the inverter circuit as shown in FIG. 1, and simultaneously fire the thyristor 11 constituting the short circuit. A protective operation can be performed.

[Effects of the Invention] As described above, according to the present invention, when an abnormality occurs in the snubber energy regeneration circuit, the overcurrent flowing at that time is detected and the system is installed before the GTO elements constituting the inverter circuit are damaged. It is possible to provide a protection method for a snubber energy regeneration circuit that can protect and stop an inverter circuit.

[Brief explanation of drawings]

FIG. 1 is a circuit configuration diagram showing an embodiment of the present invention, FIG. 2 is a time chart for explaining the operation of the embodiment, and FIG.
The figure is a circuit configuration diagram for explaining the overcurrent flowing in the snubber energy regeneration circuit for one GTO element in the same embodiment, and FIGS. 4 and 5 are circuit configuration diagrams showing other embodiments of the present invention, respectively. 6 is a time chart for explaining the operation of the embodiment shown in FIG. 5, FIG. 7 is a circuit diagram showing the configuration of the inverter device, and FIG. 8 is a snubber adopted for the GTO element of the inverter device. A circuit diagram showing details of the energy regeneration circuit, and FIG. 9 is a time chart for explaining the operation of FIG. 8. 1... Rectifier, 2... Input transformer, 3... Inverter, 4... Output transformer, 5... DC reactor, 6
...Reactor, 7a, 7b...DC filter capacitor, 10...Short circuit reactor, 11...
Cyrisk for short circuit, 12-17-G T 0, 12
a ~ 17 a -- Cyrisk, 12b ~ 17b
... Snubber capacitor, 12c to 17c... Snubber diode, 12d to 17d... Reactor, 12e
~17e... Thyristor, 18... Rectifier, 19.
... Comparison circuit, 20 OR circuit, 21-26... AND circuit, 27.28... Gate circuit, 29... Current transformer. Applicant's agent Patent attorney Takehiko Suzue

Claims (1)

[Claims] In a snubber energy regeneration circuit that regenerates snubber energy in a snubber circuit of self-extinguishing elements constituting an inverter circuit to the main circuit of the inverter, when an overcurrent flowing during an abnormality in the snubber energy regeneration circuit is detected, the self Blocking the gate of the arc-extinguishing element, simultaneously blocking the gate of the rectifier with control pole of the snubber energy circuit, and igniting the rectifier with control pole for shorting provided in the main circuit of the inverter. A method of protecting a snubber energy regeneration circuit.