JP5669686B2 - Gate drive device for switching element - Google Patents

Description

  The present invention relates to a gate driving device for a semiconductor switching element of a three-level power converter.

In recent years, with the progress of power electronics technology, various power conversion circuits have been put into practical use. In general, the power conversion circuit is a circuit that freely converts the form of power between DC and AC, and there are several methods such as a two-level method and a three-level method depending on the circuit configuration.
FIG. 2A shows an example of a three-level power converter. The three-level power converter is applied when a circuit is formed by using a switching element having a low withstand voltage in an application where the DC voltage is high. In addition, since the three-level power converter can output a waveform that is closer to a sine wave than the two-level method, it is suitable for applications in which regulations such as harmonics are severe.

2 (a), 4-7 are IGBTs, 8, 9 are neutral point clamping diodes, 10, 11 are power supply stabilization capacitors, 36 is an AC terminal, 37 and 38 are DC terminals, 37 is a positive electrode, Reference numeral 38 denotes a negative electrode, and 39 to 42 denote gate driving devices. The operation will be briefly described below.
Consider the case of converting DC to AC. When a DC voltage is applied to the DC terminals 37 and 38, only the IGBTs 4 and 5 are turned on. When the IGBTs 5 and 6 are turned on, 0V is applied. When only the IGBTs 6 and 7 are turned on, a negative output is obtained. Each is output. As described above, the three-level main circuit is characterized in that it can output three levels of voltages of plus, 0, and minus by turning on two IGBTs as a set.

What must be noted in the three-level power conversion device is an arm short-circuit phenomenon caused by simultaneously turning on three IGBTs in series such as IGBT4, IGBT5, IGBT6, or IGBT5, IGBT6, and IGBT7. In particular, when such a three-level power conversion device is used for a railway vehicle, the DC voltage may exceed 1000V, and when an arm short circuit occurs, a short circuit between the P-C or C-N due to the IGBT (power short circuit state) Thus, an excessive current flows and the IGBT is destroyed.
Therefore, in the normal three-level main circuit, a sequence of control signals for driving the IGBT is set so that the IGBT 4, IGBT 5, IGBT 6, and the IGBT 5, IGBT 6, and IGBT 7 are not turned on at the same time so as not to cause an arm short circuit. However, in reality, there is a problem that an arm short circuit occurs due to IGBT4, IGBT5, IGBT6, or IGBT5, IGBT6, IGBT7 being simultaneously turned on due to an unexpected event such as an error in the control sequence or a failure of the gate driving device. It was.

  As a technique for solving such a problem, an arm short circuit is prevented by installing a function for preventing the gate driving device 39 and the gate driving device 41 and the gate driving device 40 and the gate driving device 42 from being turned on simultaneously. A technique is disclosed in Japanese Patent Application Laid-Open No. 2007-185024.

  FIG. 2B shows a configuration diagram of a three-level main circuit using a gate driving device equipped with a simultaneous ON prevention function. In FIG. 2B, the same components as those in FIG. In FIG. 2B, 1 is a control logic unit, 12 to 15 are drive commands, 16 to 19 are ON permission signals, and 43 to 46 are gate drive device boards equipped with a simultaneous ON prevention function. In general, since insulation is required between the control logic unit 1 and the IGBT connected to the high-voltage main circuit, the drive commands 12 to 15 are communicated using optical fibers. In addition, the ON permission signals 16 to 19 are also communicated via the optical fiber.

In this circuit, the gate drive device substrates 43 to 46 equipped with the simultaneous on-prevention function monitor the operation state of the IGBT, and only when the IGBT is turned off, send a signal to permit the turn-on to the paired gate drive device substrate, Arm short circuit is prevented. For example, the simultaneous on-prevention function-equipped gate drive device substrate 43 monitors the state of the IGBT 4 and sends an on permission signal 18 to the paired simultaneous on-prevention function-equipped gate drive device substrate 45 only when the IGBT 4 is off. The gate drive device board 45 with the simultaneous on prevention function can turn on the IGBT 6 only when the on permission signal 18 is sent.
On the other hand, the gate drive device board 45 equipped with the simultaneous on prevention function detects that the IGBT 6 is turned off, and sends an on permission signal 16 to the gate drive equipment board 43 equipped with the simultaneous on prevention function. The IGBT 4 can be turned on only when the permission signal 16 is sent. By adopting such a configuration, it is prohibited to simultaneously turn on three IGBTs in series at the same time, and an arm short circuit is prevented.
In realizing this configuration, in order to communicate an ON permission signal between gate drive device substrates having different potentials, communication is generally performed by optical signal transmission by connecting an optical fiber or the like between the gate drive device substrates.

JP 2007-185024 A

However, the above-described prior art has the following problems.
That is, as shown in FIG. 2B, when an optical fiber is used for optical signal transmission between gate drive devices, a large number of optical fibers (in the case of FIG. 4), it becomes necessary to connect them, and a new wiring space is required for these optical fibers, which increases the size of the converter.
In addition, optical fibers have the disadvantage that if an unnecessary bending stress is applied, the fiber will be broken and it will not be possible to transmit signals. Careful handling is required, making wiring work complicated and improving durability. There was also a problem. Furthermore, many optical fibers including drive commands (12 in FIG. 2B) had to be wired, and there was a problem that they were mistakenly wired.
SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to solve the above-described problems, and the gate driving device of the three-level power converter has a simultaneous on prevention circuit, and the number of components of the three-level power converter is reduced and reliable. It is to provide a gate driving device with improved performance.

In order to solve the above problems, in a three-level power conversion device, a gate driving device that drives both the first IGBT and the third IGBT, and a gate driving that drives both the second IGBT and the fourth IGBT. This is achieved by configuring the device with a gate driving device mounted on a single substrate.
More specifically, the gate switching device for a semiconductor switching element according to the present invention employs the following technical means. That is,
(1) First to fourth semiconductor switching elements sequentially connected in series between a pair of DC power supply terminals, and first to fourth switching elements connected to the first to fourth switching elements, respectively, for driving these semiconductor switching elements. 1 to 4 gate drive circuits, plus output when only the first and second semiconductor switching elements are turned on, zero output when only the second and third semiconductor switching elements are turned on, and third And a three-level power converter for converting to alternating current by outputting a negative output when only the fourth semiconductor switching element is turned on, the first drive circuit, the third drive circuit, and the first Two drive circuits and the fourth drive circuit are mounted on the same substrate, and on each substrate, the gate output in the two gate drive circuits The road, connected to the logic circuit to one another via a communication line, one of the gate drive circuit by turning off the other gate drive circuit when turned on, and to prevent simultaneous ON.

(2) In the gate driving device for a semiconductor switching element, the minimum insulation distance defined in the standard is ensured based on the DC voltage applied to the two gate driving circuits on the same substrate.

(3) In the gate driving device for a semiconductor switching element, an insulating slit is provided between two gate driving circuits on the same substrate.

(4) In the gate drive device for a semiconductor switching element, the gate output circuits of the two gate drive circuits are formed on the same substrate by using a pulse transformer, an optical element such as a high voltage photocoupler or an optical fiber, and a high insulation capacitance. The logic circuit is connected through an insulation signal transmission circuit using at least one of the above.

  According to the present invention, optical signal transmission between the gate drive device substrates of the first IGBT and the third IGBT, and connection between the gate drive device substrates of the second IGBT and the fourth IGBT and exchange of an on permission signal are performed. As a result, it is possible to prevent an arm short circuit and to improve the workability at the time of assembling the gate drive device and prevent incorrect wiring by wiring the ON permission signal in the gate drive device substrate.

The figure which shows the structure of the 3 level power converter device to which the gate drive device of Example 1 of this invention is applied. (A) is an example of a three-level power conversion device as a premise, and (b) is a diagram showing a configuration of a three-level power conversion device to which a gate drive device equipped with a simultaneous on-prevention function of the prior art is applied. The figure which shows the structure of the 3 level power converter device to which the gate drive device of Example 2 of this invention is applied. The figure which shows the structure of the 3 level power converter device to which the gate drive device of Example 3 of this invention is applied.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

[Example 1]
FIG. 1 shows an example in which the gate driving device according to the first embodiment of the present invention is applied to a three-level power conversion device.
The same components as those in FIGS. 2A and 2B are denoted by the same reference numerals.
In FIG. 1, 20-23 are AND circuits, 24-27 are IGBT on determination circuits, 28-31 are gate drive circuits, and 32-35 are gate output circuits. A gate drive circuit 28 having a gate output circuit 32 that outputs an ON signal to the first IGBT 4 and a gate drive circuit 29 having a gate output circuit 33 that outputs an ON signal to the third IGBT 6 will be described later. It is mounted on the same substrate together with an AND circuit and a GBT on determination circuit, and constitutes a gate driving device 2.
Similarly, a gate drive circuit 30 having a gate output circuit 34 that outputs an ON signal to the second IGBT 5 and a gate output circuit 35 that outputs an ON signal to the fourth IGBT 7. 31 is mounted on the same substrate together with an AND circuit and a GBT on determination circuit, which will be described later, and constitutes a gate driving device 3.

Since the gate driving device 2 and the gate driving device 3 have the same configuration, the operation will be described below using the gate driving device 2.
The drive signal from the control logic unit 1 is output to the AND circuit 20 via the drive command 12, and the GBT on determination circuit 25 turns off the third IGBT 6 based on the signal from the gate output circuit 33. The ON permission signal 16 is output to the AND circuit 20, and the AND circuit 20 takes an AND of the drive command 12 and the ON permission signal 16, and outputs an ON signal when both are at the Hi level.
That is, only when the command from the control logic unit 1 is “ON”, the third IGBT 6 is OFF, and the ON permission signal 16 is “permitted”, the AND circuit 20 and the gate output circuit 32 are used. The first IGBT 4 can be turned on.

At this time, in the gate output circuit 32, the IGBT 4 is turned on, and at the same time, the IGBT on determination circuit 24 determines that the first IGBT 4 is turned on, and outputs the ON permission signal 18 output to the AND circuit 21 to Lo. By pulling down to the level, the gate drive circuit 29 is notified that the first IGBT is turned on.
When the on permission signal 18 is at the Lo level, the output of the AND circuit 21 is always off regardless of the state of the drive command 14 from the control logic unit 1 to the gate output circuit 33, and prevents the IGBT 6 from being turned on. This realizes a so-called simultaneous ON prevention function that protects the IGBT 6 from being turned ON when the IGBT 4 is ON.

On the other hand, when the IGBT 6 is turned on due to an unexpected cause such as a malfunction even though the IGBT 4 is turned on, the IGBT on determination circuit 25 detects this and turns on the output to the AND circuit 20. The permission signal 16 is set to Lo level. In the AND circuit 20, since the ON permission signal 16 becomes Lo level, the OFF signal is output to the gate output circuit 32 even if the drive command 12 from the control logic unit 1 is Hi level, that is, ON command. As a result, the gate drive circuit 32 lowers the gate voltage of the IGBT 4 to turn it off by suppressing it to a voltage lower than the threshold voltage of the IGBT.
Hereinafter, the features of the first embodiment will be described in comparison with FIG. 2B of the prior art.

As described above, in the prior art of FIG. 2B, in order to realize the simultaneous ON prevention function, the signal wiring must be laid between the circuit boards constituting the individual gate driving devices 39 to 41 for the IGBT4 to IGBT7. There were various problems because it was necessary. On the other hand, according to the present embodiment, as shown in FIG. 1, the gate drive circuit 28 of the IGBT 4 and the gate drive circuit 29 of the IGBT 6, and the gate drive circuit 30 of the IGBT 5 and the gate drive circuit 31 of the IGBT 7 are driven by the gate. The gate drive devices are individually integrated by mounting the communication lines for the on-permission signals 16 to 19 connected on the substrate as the devices 2 and 3 on the substrate constituting the gate drive device. Unlike the case of using this board, wiring for connecting the boards can be made unnecessary, and it is possible to improve workability during assembly and to prevent erroneous wiring.
In addition, since the number of gate drive device substrates can be reduced by half, the number of components of the three-level power conversion device can be reduced and the cost can be reduced.
Note that the distance between the gate drive circuits 28 and 29 mounted on the same substrate is required for insulation as shown below.

  For example, a gate drive device applied to a railway vehicle will be described as an example. When applied to a railway vehicle, the voltage at the DC terminal is generally 750 V or higher. Since the potential of the gate driving device substrate is the same as the emitter potential of the IGBT, a voltage of 750 V is applied between the gate driving circuits 30 and 31. The overhead line voltage is known to fluctuate when the railway vehicle is traveling, and reaches a maximum of 1000 V in the case of a 750 V overhead line. It is known from the standard that the insulation distance required to ensure insulation of the gate drive circuits 30 and 31 against this voltage is 5 mm. On the other hand, between the IGBT 4 and the IGBT 6, in the case of a three-level main circuit, only a voltage that is half the DC voltage is applied due to the circuit configuration. For this reason, the insulation between the gate drive circuits 28 and 29 may be ensured with respect to 500 V that is 1/2 of the maximum 1000 V, and a distance of 2.5 mm is sufficient. As described above, it is possible to realize further downsizing of the substrate by ensuring a sufficient insulation in accordance with the standard and minimizing the distance between the gate drive circuits 30 and 31 as necessary.

[Example 2]
FIG. 3 shows a gate drive apparatus according to the second embodiment of the present invention.
The same components as those in FIGS. 1, 2A, and 2B are denoted by the same reference numerals. In FIG. 3, reference numeral 40 denotes an insulating communication means.
The features of the second embodiment will be described in comparison with FIG. 1 of the first embodiment.
As described above, in the first embodiment shown in FIG. 1, the ON permission signals 16 and 18 are communicated using optical fibers. According to the second embodiment, as shown in FIG. 3, a pulse transformer, a high withstand voltage photocoupler, a conventional optical fiber with a shortened length, or a high insulation capacitance is used as an insulation signal transmission circuit 40 as shown in FIG. be able to. By these, the effect shown in Example 1 of FIG. 1 can be acquired similarly.

[Example 3]
FIG. 4 shows a gate driving apparatus according to Embodiment 3 of the present invention.
The same components as those in FIGS. 1, 2A, 2B, and 3 are denoted by the same reference numerals. In FIG. 4, 41 is an insulation slit.
The features of the third embodiment will be described in comparison with FIG. 1 of the first embodiment.
As described above, the first embodiment of FIG. 1 requires an insulating region of 5 mm or more between the gate drive circuits 30 and 31. In FIG. 4, the insulating region can be shortened by inserting the insulating slit 41. According to the standard, it is known that the minimum spatial distance in air is 4 mm, so that the insulating region can be shortened to 4 mm. On the other hand, an insulating region of 2.5 mm or more is required between the gate drive circuits 28 and 29 of the first embodiment shown in FIG. In FIG. 4, the insulating region can be shortened by inserting the insulating slit 41. According to the standard, it is known that the minimum spatial distance in the air is 1.5 mm, so that the insulating region can be shortened to 1.5 mm.

In the above embodiment, an example of a three-level main circuit has been described. Of course, the present invention is not limited to a three-level main circuit. It will be apparent to those skilled in the art that it is obtained. In short, when the power is turned on at the same time, a combination of gate drive circuits that breaks down the IGBT and destroys the IGBT is mounted on one substrate, and the gate output circuit is logically connected to this substrate via communication lines. It is only necessary to connect the circuit so that at least one gate drive circuit is always turned off.
Moreover, although the example of IGBT was demonstrated as a semiconductor element, even if power devices, such as a bipolar transistor, MOSFET, and GTO, are applied, the same effect can be acquired.
Furthermore, the same effect can be obtained not only for the railway vehicle described in this embodiment but also for any multi-level power conversion circuit such as a power converter for driving a rolling roller in a steel mill or a high-voltage power supply. Can do.

  As described above, according to the present invention, in the three-level power converter, the first drive circuit and the third drive circuit, and the second drive circuit and the fourth drive circuit are respectively provided on the same substrate. The gate output circuit in the two gate drive circuits is mounted on each substrate and connected to the logic circuit through the communication line, and when one of the gate drive circuits is on, the other gate drive circuit Since the simultaneous on is prevented by turning off the power, the components of the three-level power converter can be simplified and made compact, the durability can be improved, and the simplification of the wiring work can be improved. It can be expected to be widely adopted in power converters using voltage DC power supplies.

DESCRIPTION OF SYMBOLS 1 Control logic part 2, 3 Gate drive device 4-7 IGBT
8, 9 Neutral point clamping diode 10, 11 Power stabilization capacitor 12-15 Drive command 16-19 ON permission signal 20-23 AND circuit 24-27 IGBT ON determination circuit 28-31 Gate drive circuit 32-35 Gate output Circuit 36 AC terminal 37, 38 DC terminal 40 Insulating communication means 41 Insulating slit

Claims (4)

First to fourth semiconductor switching elements sequentially connected in series between a pair of DC power supply terminals;
The first to fourth switching elements are respectively connected to the first to fourth switching elements and drive these semiconductor switching elements, and are positive when only the first and second semiconductor switching elements are turned on. 3-level power conversion that converts to zero by outputting zero output when only the second and third semiconductor switching elements are turned on, and minus output when only the third and fourth semiconductor switching elements are turned on A device,
The first driving circuit and the third driving circuit, and the second driving circuit and the fourth driving circuit are mounted on the same substrate, and the two gate driving circuits are mounted on each substrate. The gate output circuits are connected to each other via a communication line, and when one of the gate drive circuits is on, the other gate drive circuit is turned off to prevent simultaneous on. A gate driving device for a semiconductor switching element.   2. The gate driving device for a semiconductor switching element according to claim 1, wherein a minimum insulation distance defined by a standard is secured on the same substrate based on a DC voltage applied to two gate driving circuits. A gate driving device for a semiconductor switching element.   3. The gate driving device for a semiconductor switching element according to claim 2, wherein an insulating slit is provided between two gate driving circuits on the same substrate. In the gate drive device for semiconductor switching elements according to any one of claims 1 to 3,
In the same substrate, the gate output circuits of the two gate drive circuits are connected to each other through an isolation signal transmission circuit using at least one of a pulse transformer, an optical element such as a high voltage photocoupler or an optical fiber, and a high insulation capacitance. A gate driving device for a semiconductor switching element, wherein the gate driving device is connected to the logic circuit .

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