JP5542323B2 - Gate circuit - Google Patents

Description

  The present invention relates to a gate circuit of a voltage driven semiconductor element.

  2. Description of the Related Art Generally, a power conversion device that converts power by switching an IGBT (insulated gate bipolar transistor) that is a voltage-driven semiconductor element is known. In such a power conversion device, when the IGBT of the opposite arm that is turned off (the IGBT connected in series with the conducting IGBT) is short-circuited and broken, an excessive short-circuit current flows. This short circuit current may reach 10 times or more of the IGBT rated current. When such a short-circuit current flows, the IGBT is damaged.

Therefore, various studies have been made on protection against such a short-circuit current (see, for example, Non-Patent Document 1). Further, as one of the methods for such protection, it has been proposed to configure a circuit so as to include an inductance on the emitter side of the IGBT (see Non-Patent Document 2).
Romeo Letor, 1 other, “Short Circuit Behavior of IGBT's Correlated to the Intrinsic Device Structure and on the Application Circuit”, IEEE TRANSACTIONS ON INDUSTRY APPLICATIONS, IEEE, March / April 1995, Vol. 31, no. 2, p. 234-239 Kiyoaki Ninagawa, 2 others, “Examination of IGBT short-circuit protection method by gate waveform control”, IEEJ D Division paper, IEEJ, 2007, Vol. 127, No. 5, p. 478-484

  However, in the power conversion device described in the prior art document, even in normal IGBT switching, negative feedback is applied to the gate so as to reduce di / dt of the IGBT element current due to inductance. For this reason, for example, the recovery current flowing in the diode of the opposite arm when the IGBT is turned on is also suppressed. Therefore, the gate voltage of the IGBT is greatly increased. This increases the switching loss.

  Accordingly, an object of the present invention is to provide a gate circuit for a voltage-driven semiconductor element that can suppress a short-circuit current flowing in the voltage-driven semiconductor element and reduce a switching loss of the voltage-driven semiconductor element.

A gate circuit according to an aspect of the present invention is a gate circuit in which an inductor is connected in series on the emitter side of a voltage-driven semiconductor element, and drives the voltage-driven semiconductor element, the gate circuit of the voltage-driven semiconductor element A gate voltage for driving the voltage-driven semiconductor element is applied between the emitters, a driving means for driving the voltage-driven semiconductor element; and the voltage-driven type to which the gate voltage is applied by the driving means Circuit switching means for switching a circuit between the gate and the emitter of the semiconductor element between a circuit including the inductor and a circuit not including the inductor; and after the turn-on of the voltage-driven semiconductor element, the circuit switching means includes the inductor. a switching signal generating means for generating a switching signal for switching the circuit including the inductor from no circuit, wherein And a gate waveform generation means for generating a gate waveform for outputting the over G Voltage, said switching signal generating means, based on the generated said gate waveform by the gate waveform generation means generates the switching signal .

  ADVANTAGE OF THE INVENTION According to this invention, the short circuit current which flows into a voltage drive type semiconductor element can be suppressed, and the gate circuit of the voltage drive type semiconductor element which can reduce the switching loss of a voltage drive type semiconductor element can be provided.

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

(Embodiment)
FIG. 1 is a configuration diagram showing a configuration of a power conversion circuit 10 according to an embodiment of the present invention. FIG. 2 is a waveform diagram showing waveforms of the gate pulse GP and the switching signal SK generated by the gate circuit 1 according to the present embodiment. In the following drawings, the same portions are denoted by the same reference numerals, detailed description thereof is omitted, and different portions are mainly described. In the following embodiments, the same description is omitted.

  The power conversion circuit 10 includes a gate circuit 1, an IGBT 2, a diode 3, and a coil 4.

  The gate circuit 1 is a circuit that outputs a gate voltage for switching the IGBT 2.

  The IGBT 2 is a voltage driven semiconductor element. The power conversion circuit 10 converts DC power into AC power by switching the IGBT 2.

  The diode 3 is connected in antiparallel to the IGBT 2.

  The coil 4 is an element for suppressing a short-circuit current that flows when the IGBT 2 is short-circuit broken. The coil 4 is an inductor having an inductance.

  Next, a detailed configuration of the gate circuit 1 will be described.

  The gate circuit 1 includes a gate pulse generation unit 11, an on delay 12, and a switch 13.

  The gate pulse generator 11 generates a gate pulse GP that is a command for turning on or off the IGBT 2. The gate circuit 1 applies a gate voltage to the IGBT 2 in accordance with the gate pulse GP generated by the gate pulse generator 11. The waveform of the gate pulse GP indicates the waveform of the gate voltage applied between the gate and the emitter of the IGBT 2.

  The on-delay 12 receives the gate pulse GP output from the gate pulse generator 11 and outputs a switching signal SK for switching the switch 13. The on-delay 12 outputs a waveform obtained by delaying a turn-on time (rise time) by a predetermined time with respect to the input waveform.

  The switch 13 switches between the contact PA and the contact PB in accordance with the switching signal SK output from the on delay 12. When the contact PA is selected, the coil 4 is included in a circuit in which the gate circuit 1 applies a gate voltage to the IGBT 2. When the contact PB is selected, the coil 4 is not included in the circuit in which the gate circuit 1 applies the gate voltage to the IGBT 2.

  Next, the operation of the power conversion circuit 10 will be described.

  When the gate pulse GP indicates ON, the gate circuit 1 turns on the IGBT 2 by setting the gate voltage applied between the gate and the emitter to a threshold voltage or higher. When the gate pulse GP indicates OFF, the gate circuit 1 turns off the IGBT 2 by setting the gate voltage applied between the gate and the emitter to a threshold voltage or less.

  The gate circuit 1 selects the switch 13 as the contact PA before starting to drive the IGBT 2. When the switching signal SK indicates PA, the gate circuit 1 switches the switch 13 to the contact PA. When the switching signal SK indicates PB, the gate circuit 1 switches the switch 13 to the contact PB.

  As shown in FIG. 2, when the gate pulse GP is input from the gate pulse generator 11, the on-delay 12 outputs a waveform whose rising edge is delayed from time t1 to time t2 as the switching signal SK. The time between the time t1 and the time t2 is a time preset in the on-delay 12. This set time is set to be approximately equal to or slightly later than the turn-on time of the IGBT 2.

  With the above-described configuration, the gate circuit 1 applies a gate voltage between the gate and the emitter not including the coil 4 until the IGBT 2 is turned on from off. The gate circuit 1 applies a gate voltage between the gate and the emitter including the coil 4 while the IGBT 2 is turned on.

  According to this embodiment, the following effects can be obtained.

  The gate circuit 1 applies a gate voltage to a circuit that does not include an inductance until the IGBT 2 is turned from OFF to ON. The gate circuit 1 applies a gate voltage to the circuit including the inductance while the IGBT 2 is turned on.

  As a result, the power conversion circuit 10 can suppress an excessive short-circuit current that occurs due to a short-circuit breakdown of the IGBT of the opposite arm when the IGBT 2 is turned on, without increasing the switching loss of the IGBT 2 at the normal time.

  Here, the short-circuit current generated during the period from when the IGBT 2 is turned off to when it is turned on is not suppressed. However, the short-circuit current generated during this period is less serious than the short-circuit current generated when the IGBT 2 is conducting (see Non-Patent Document 1). Therefore, the power conversion circuit 10 has almost no influence on the function as short circuit protection.

  Note that the present invention is not limited to the above-described embodiment as it is, and can be embodied by modifying the constituent elements without departing from the scope of the invention in the implementation stage. In addition, various inventions can be formed by appropriately combining a plurality of components disclosed in the embodiment. For example, some components may be deleted from all the components shown in the embodiment. Furthermore, constituent elements over different embodiments may be appropriately combined.

The block diagram which shows the structure of the power converter circuit which concerns on embodiment of this invention. The wave form diagram which shows the waveform of the gate pulse and switching signal which the gate circuit which concerns on this embodiment produces | generates.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Gate circuit, 2 ... IGBT, 3 ... Diode, 4 ... Coil, 10 ... Power conversion circuit, 11 ... Gate pulse production | generation part, 12 ... On-delay, 13 ... Switch.

Claims (3)

An inductor is connected in series to the emitter side of the voltage-driven semiconductor element, and the gate circuit drives the voltage-driven semiconductor element,
Drive means for driving the voltage-driven semiconductor element by applying a gate voltage for driving the voltage-driven semiconductor element between a gate and an emitter of the voltage-driven semiconductor element;
Circuit switching means for switching a circuit between a gate and an emitter of the voltage-driven semiconductor element to which the gate voltage is applied by the driving means between a circuit including the inductor and a circuit not including the inductor;
A switching signal generating means for generating a switching signal for switching from a circuit not including the inductor to a circuit including the inductor by the circuit switching means after the voltage-driven semiconductor element is turned on ;
Gate waveform generating means for generating a gate waveform for outputting the gate voltage,
The switching signal generating means generates the switching signal based on the gate waveform generated by the gate waveform generating means.
Gate circuit according to claim. The switching signal generation means includes an on-delay timer that inputs the gate waveform generated by the gate waveform generation means and outputs a waveform obtained by delaying the rise time of the gate waveform signal as the switching signal. The gate circuit according to claim 1. A voltage-driven semiconductor element driven by a gate voltage;
An inductor connected in series to the emitter side of the voltage-driven semiconductor element;
Driving means for applying the gate voltage between the gate and emitter of the voltage-driven semiconductor element to drive the voltage-driven semiconductor element;
Circuit switching means for switching a circuit between a gate and an emitter of the voltage-driven semiconductor element to which the gate voltage is applied by the driving means between a circuit including the inductor and a circuit not including the inductor;
A switching signal generating means for generating a switching signal for switching from a circuit not including the inductor to a circuit including the inductor by the circuit switching means after the voltage-driven semiconductor element is turned on;
Gate waveform generating means for generating a gate waveform for outputting the gate voltage,
The switching signal generating means generates the switching signal based on the gate waveform generated by the gate waveform generating means.
The power converter characterized by this.

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