JP2009253699A - Driver circuit for semiconductor device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a driver circuit for a semiconductor device which surely reduces switching noise that is caused accompanied with high-speed current cutoff of a switching element capable of high-speed turning-off, and is capable of stably operating the driver circuit system of the switching element. <P>SOLUTION: The driver circuit for a semiconductor device includes a feedback circuit 10 wherein the cathode of a diode Dr is connected to the gate of a semiconductor device Q, the anode of the diode is connected to the source of the semiconductor device, and a resistor Rr is inserted and connected between the gate and the cathode or between the source and the anode. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a drive circuit for a semiconductor element.

Conventionally, a MOS field effect transistor having a drain, a gate and a source as a semiconductor element, a floating inductance connected between the source and the source terminal, a connection between the source terminal and the gate, and a cathode connected to the gate side The high-voltage high-speed is adjusted so that the MOS field-effect transistor can be turned on via the unidirectional diode when a high-voltage high-speed surge is applied to the stray inductance. 2. Description of the Related Art An insulated gate semiconductor device that can suppress latch-up against a surge is also known (see, for example, Patent Document 1).
JP-A-2004-78992

  However, in the configuration described in Patent Document 1 described above, when a high-voltage and high-speed surge is applied, the on-state of the element continues for a long time, and a drive circuit system that changes the on / off state of the switching element is not used. There was a problem that it might become stable. On the other hand, when the value of the floating inductance is small, there is a problem that the element is difficult to be turned on and its adjustment is difficult.

  SUMMARY OF THE INVENTION Therefore, the present invention provides a semiconductor element drive circuit capable of reliably reducing switching noise generated due to high-speed current interruption of a switching element capable of high-speed turn-off and stably operating a drive circuit system of the switching element. The purpose is to provide.

In order to achieve the above object, a drive circuit for a semiconductor device according to a first aspect of the present invention includes:
A cathode of a diode is connected to the gate of the semiconductor element, and an anode of the diode is connected to a source of the semiconductor element;
And a feedback circuit in which a resistor is inserted and connected between the gate and the cathode or between the source and the anode.

  Accordingly, an on signal is given to the gate in synchronization with switching noise generated when the semiconductor element is turned off, and the switching noise can be reduced by using the semiconductor element as an attenuation resistor, and the semiconductor element is turned on by the resistance. The period can be adjusted to be instantaneous, and the drive circuit system of the semiconductor element can be stably operated.

A second invention is a drive circuit for a semiconductor device according to the first invention.
The semiconductor element is a semiconductor element having a unipolar structure.

  As a result, even in a unipolar semiconductor element capable of high-speed operation, switching noise when the element is turned off can be suppressed, and the active gate control circuit can be applied to a high-speed semiconductor element.

A third invention is a drive circuit for a semiconductor device according to the first or second invention.
The semiconductor element is a MOSFET.

  As a result, a driving circuit having a stable operation with little switching loss can be realized by using a MOSFET capable of high-speed operation.

A fourth invention is a drive circuit for a semiconductor device according to any one of the first to third inventions,
The diode is a Schottky barrier diode or a high-speed diode having an operation speed higher than that of a Schottky barrier diode.

  As a result, an ON signal can be given to the gate in synchronization with switching noise generated when the semiconductor element is turned off, and active gate control can be reliably performed.

A fifth invention is a drive circuit for a semiconductor device according to any one of the first to fourth inventions,
The resistor is set such that the current supplied to the gate by the feedback circuit is not oscillated when the semiconductor element is switched off.

  As a result, the semiconductor element is turned on for a moment, and the switching operation of the drive circuit system of the semiconductor element can be reliably stabilized.

A sixth invention is a drive circuit for a semiconductor element according to any one of the first to fifth inventions,
A snubber capacitor is connected between the drain of the semiconductor element and the source.

  Thereby, generation | occurrence | production of a surge voltage can also be suppressed, suppressing high frequency switching noise.

A seventh invention is a drive circuit for a semiconductor element according to the sixth invention,
The semiconductor element and the diode are accommodated in a module,
The resistor and the snubber capacitor are provided outside the module.

  Thereby, it is possible to perform setting so that the drive circuit in the module operates properly later.

A drive circuit for a semiconductor element according to an eighth invention is a drive circuit for a semiconductor device housed in a module,
A feedback circuit in which a cathode of a diode is connected to a gate of the semiconductor element, and an anode of the diode is connected to a source of the semiconductor element;
The on-resistance of the diode is set such that the current supplied to the gate by the feedback circuit does not oscillate when the semiconductor element is switched off.

  Thereby, the circuit configuration can be simplified and the number of parts can be reduced.

  According to the present invention, it is possible to reduce the switching noise generated when the semiconductor element is turned off and to stably operate the drive circuit system of the semiconductor element.

  The best mode for carrying out the present invention will be described below with reference to the drawings.

  FIG. 1 is an overall configuration diagram of a semiconductor element drive circuit 50 according to a first embodiment to which the present invention is applied. In FIG. 1, the semiconductor element drive circuit 50 according to the first embodiment includes a semiconductor element Q and a feedback circuit 10. A snubber capacitor Cs may be connected to the semiconductor element Q as necessary. In the first embodiment, an example in which a snubber capacitor Cs is connected will be described. The feedback circuit 10 includes a diode Dr and a resistor Rr.

  Further, the drive circuit 50 of the semiconductor element Q according to the present embodiment may include the gate drive circuit 20 as a related component. Furthermore, in the drive circuit 50 for the semiconductor element Q according to the present embodiment, the input capacitance Ciss and the output capacitance Coss that exist parasitically in the semiconductor element Q are shown in an equivalent circuit. Similarly, a drain side wiring inductance Lsd and a source side wiring inductance Lss are shown as equivalent circuits as inductances parasitic on the wiring. Similarly, the wiring inductance Ls1 is shown above the drain side wiring inductance Lsd, and the wiring inductance Ls2 is shown below the source side wiring inductance Lss. As terminals of the semiconductor element Q, a drain terminal drain, a gate terminal gate, a signal source terminal source (sig), and a main circuit source terminal source (power) are shown.

  The semiconductor element Q is a switching element that performs an on / off operation when a voltage is applied to a gate. As the semiconductor element Q, a switching element that operates at a higher speed than the IGBT may be applied. For example, a semiconductor element having a unipolar structure in which current interruption is fast may be applied. In the drive circuit of the semiconductor element Q according to the present embodiment, the semiconductor element Q is applied with an n-type power MOSFET having a unipolar structure capable of cutting off current sharply and capable of operating at a higher speed than the IGBT. Switching operation can be performed at high speed. Further, since the n-type MOSFET is applied to the semiconductor element Q in the first embodiment, the semiconductor element Q is turned on and becomes conductive when a positive voltage higher than a predetermined voltage is applied to the gate. Yes.

  The semiconductor element Q has a parasitic input capacitance Ciss and an output capacitance Coss. This is a capacitance determined by the characteristics of the semiconductor element Q.

  The snubber capacitor is a capacitor for suppressing a surge voltage. When a high-speed surge voltage is applied to the semiconductor element Q, the generated current is absorbed and suppressed.

  The drain side wiring inductance Lsd and the source side wiring inductance Lss are inductances that exist parasitically in the wiring. However, in the drive circuit 50 of the semiconductor element Q according to the present embodiment, the induced electromotive force generated in the wiring inductance Lss is generated. Effectively reduce switching noise. Details of this point will be described later. The wiring inductances Ls1 and Ls2 are also inductances that exist parasitically in the wiring.

  The feedback circuit 10 is a circuit for feeding back an on signal to the semiconductor element Q by feeding back high frequency vibration (switching noise) generated when the semiconductor element Q is turned off to the gate of the semiconductor element Q. Details of this point will be described later.

  The gate drive circuit 20 is a circuit for driving the semiconductor element Q to be switched. In FIG. 1, switches S1 and S2 are shown as equivalent circuits. As described above, switching control of the semiconductor element Q is performed by applying a predetermined gate voltage to the gate of the semiconductor element Q. In FIG. 1, the switch S1 is turned on and the switch 2 is turned off to turn on the semiconductor element Q. Is turned on, the switch S1 is turned off and the switch S2 is turned on to control the semiconductor element Q to be turned off.

  Next, an example in which the application of the drive circuit 50 for the semiconductor element Q according to the present embodiment is effective will be described with reference to FIGS.

  FIG. 3 is a diagram showing a driving circuit 150 for a semiconductor element Q according to a comparative example in which the feedback circuit 10 is removed from the driving circuit 50 for the semiconductor element Q according to the present embodiment shown in FIG. The individual components have already been described with reference to FIG.

  FIG. 4 is a diagram showing operation waveforms of the drive circuit 150 of the semiconductor element Q according to FIG. FIG. 4A is an operation waveform diagram when the snubber capacitor Cs is not provided, and FIG. 4B is an operation waveform diagram when the snubber capacitor Cs is provided. In FIG. 4, the horizontal axis represents time t [s], and the vertical axis represents Vg as the gate voltage, ich as the channel current flowing through the semiconductor element Q, id as the drain current, and Vds as the drain-source voltage. , Iss indicates the source current.

  3 and 4A, when the semiconductor element Q is in the ON state (t <t1), current flows through the surrounding wiring inductances Ls1, Ls2, the drain side wiring inductance Lsd, and the source side wiring inductance Lss. In the case where the snubber capacitor Cs in FIG. 4A is not provided, when the semiconductor element Q is turned off (t = t1), the channel current ich flowing through the semiconductor element Q is cut off, and the output capacitance Coss of the semiconductor element Q and the wiring Resonance is generated by the inductances Ls1, Ls2, the drain side wiring inductance Lsd, and the source side wiring inductance Lss. At this time, if the resonance voltage (surge voltage) generated in the output capacitance Coss increases, the semiconductor element Q may be destroyed.

  Therefore, as shown in FIG. 4B, when a snubber capacitor Cs having a capacitance larger than the output capacitance Coss is connected, the surge voltage can be suppressed as can be seen from id and Vds. However, when ich is cut off at the time of turn-off (t = t1), a new resonance circuit is formed via the output capacitance Coss, drain side wiring inductance Lsd, source side wiring inductance Lss, and snubber capacitor Cs. As shown by iss, resonance different from that in FIG.

  Here, a power MOSFET is applied to the semiconductor element Q, which is smaller than the IGBT and designed to have a small source-side wiring inductance Lss, drain-side wiring inductance Lsd, and output capacitance Coss. It is easy to generate switching noise having a higher frequency than the switching noise generated in the above.

  FIG. 5 is a high-frequency equivalent circuit diagram of the drive circuit 150 of the semiconductor element Q according to FIG. 3 for explaining the high-frequency resonance (switching noise) ihf generated in FIG. In FIG. 5, Ron simulates the on-resistance of the semiconductor element Q (power MOSFET), and changes depending on the gate voltage Vg. Further, the switching noise ihf becomes ON resistance Ron = ∞ when the semiconductor element Q is completely turned off, and the switching noise ihf circulates the snubber capacitor Cs−the drain side wiring inductance Lsd−the output capacitance Coss−the source side wiring inductance Lss. . Here, when snubber capacitor Cs >> output capacitance Coss, switching noise ihf can be regarded as parallel resonance of drain side wiring inductance Lsd, source side wiring inductance Lss−output resistance Coss−on resistance Ron. Therefore, switching noise can be attenuated if the semiconductor element Q is turned on again to reduce the on-resistance Ron.

  Based on the points described in FIG. 5, the driving circuit 50 for the semiconductor element Q according to the present embodiment will be described with reference to FIG. FIG. 2 is a diagram showing operation waveforms of the drive circuit 50 of the semiconductor element Q according to the present embodiment of FIG. As described with reference to FIG. 5, if the semiconductor element Q can be turned on again when the switching noise ihf is generated, the generated parallel resonance can be reduced and the switching noise ihf can be attenuated. In order to cause the semiconductor element Q to perform such an operation, the feedback circuit 10 is provided in the drive circuit 50 of the semiconductor element Q according to the present embodiment of FIG.

  In FIG. 1, a diode Dr forming a feedback circuit 10 and a resistor Rr are connected between a gate and a source of a semiconductor element Q. There are two types of sources: a signal source terminal source (sig) and a main circuit source terminal source (power). The diode Dr is connected to the main circuit source terminal source (power) side. The diode Dr has a cathode connected to the gate of the semiconductor element Q and an anode connected to the source. The diode Dr and the resistor Rr are connected in series. In FIG. 1, the diode Dr and the resistor Rr are inserted and connected between the cathode of the diode Dr and the gate of the semiconductor element Q. May be inserted and connected.

  Next, the operation of the drive circuit 50 for the semiconductor element Q according to the present embodiment will be described with reference to FIGS. FIG. 2 is a diagram illustrating operation waveforms of the drive circuit 50 of the semiconductor element Q according to the first embodiment. 2, Vg is a gate voltage, ich is a channel current, id is a current flowing into the drain, Vds is a drain-source voltage, ihf is switching noise (current), and ir is a resonance current.

  FIG. 2A is a diagram showing a conventional operation waveform to be compared. 1 and 2A, when the gate voltage Vg is turned off, the channel current ich does not flow, and the current id does not flow into the drain. However, as shown in FIG. 1, due to electromagnetic induction action, current flows through the output capacitance Coss to generate the drain-source voltage Vds, which is suppressed by the snubber capacitor Cs. At this time, the drain side wiring inductance Another resonance occurs among Lsd, source-side wiring inductance Lss, output capacitance Coss, and snubber capacitor Cs, and switching noise ihf is generated.

  Here, if the feedback circuit 10 does not exist, the switching noise ihf remains as shown in FIG. 2A. However, when the switching noise ihf occurs in the driving circuit of the semiconductor element Q according to the present embodiment. In addition, due to electromagnetic induction, an induced electromotive force having a high potential at the lower side is generated at both ends of the wiring inductance Lss, and a current due to the voltage generated by the induced electromotive force is applied to the semiconductor element Q via the diode Dr and the resistor Rr. A feedback circuit 10 that flows into the gate is formed. When a current flows from the source-side wiring inductance Lss toward the gate of the semiconductor element Q, charges are accumulated in the input capacitance Ciss of the semiconductor element Q, and the gate voltage Vg increases. When the semiconductor element Q is turned on due to an increase in the gate voltage Vg, the switching noise ihf is consumed by the on-resistance Ron of the semiconductor element Q, and the switching noise ihf can be suppressed.

  FIG. 2B is a diagram illustrating operation waveforms of the drive circuit 50 for the semiconductor element Q according to the first embodiment. That is, it is an illustration showing an operation waveform when the induced electromotive force generated by the switching noise is fed back to the gate of the semiconductor element Q by the feedback circuit 10 of the driving circuit 50 of the semiconductor element Q according to the present embodiment. FIG. 2B shows that the channel current ich flows at the same timing when the gate voltage Vg is decreasing and increases only while the semiconductor element Q is turned on. In addition, it is shown that the resonance current ir flows at the same timing, thereby suppressing the switching noise ihf. As described above, according to the driving circuit 50 for the semiconductor element Q according to the present embodiment, when the switching noise ihf is generated, it is detected by the induced electromotive force generated by the wiring inductance Lss and is synchronized with this detection signal. By applying an ON signal to the gate voltage, the semiconductor element Q can be turned on, and the switching noise ihf can be attenuated by the ON resistance Ron of the semiconductor element Q. That is, even when the semiconductor element Q is turned off at high speed and high-frequency switching noise ihf is generated, feedback control for attenuating the switching noise ihf can be automatically performed in synchronization with this, so that high speed and low loss can be achieved. A turn-off operation can be performed. From the viewpoint of quickly feeding back the current due to the induced electromotive force generated in the source side wiring inductance Lss to the gate of the semiconductor element Q, it is preferable that the diode Dr is a high-speed diode Dr with good frequency characteristics. For example, a Schottky barrier diode or the like may be applied. In addition, various diodes Dr can be applied as long as the diode Dr is faster than a normal PIN diode and is at a level close to or higher than that of a Schottky barrier diode.

  FIG. 6 is an equivalent circuit diagram for explaining an operation at the time of feedback of the drive circuit 50 of the semiconductor element Q according to the first embodiment. In FIG. 6, the semiconductor element Q shown in FIG. 1 is replaced with a variable resistor Ron. Zg is an output impedance of the switch S2 of the gate drive circuit 20 in FIG. 1, and is a discharge resistance for the input capacitance Ciss at the time of turn-off. Other components are the same as those of the drive circuit 50 of the semiconductor element Q shown in FIG.

  In FIG. 6, the input capacitance Ciss of the semiconductor element Q forms a circuit via a parasitic source side wiring inductance Lss, a diode Dr, a resistor Rr, and an impedance Zg. When the semiconductor element Q is turned off, the variable resistor Ron is in the ∞ state. Switching noise ihf is generated due to the turn-off of the semiconductor element Q, and the resonance current ir flows to the input capacitance Ciss by the induced electromotive voltage of the source side wiring inductance Lss accompanying the generation of the switching noise ihf. When the input capacitance Ciss is charged by the resonance current ir, the semiconductor element Q is turned on and the variable resistance Ron is reduced, so that the value of the switching noise ihf is rapidly reduced as shown in FIG. As described above, after the switching noise ihf is generated, the switching noise ihf can be drastically reduced by reducing the variable resistance Ron and causing the switching noise ihf to flow therethrough.

  Next, how to set the resistance Rr will be described with reference to FIGS. FIG. 7 is an equivalent circuit diagram for explaining in more detail the operation at the time of feedback of the drive circuit of the semiconductor element Q according to the present embodiment.

  In FIG. 7, when the switching noise ihf is generated at the time of turn-off, the induced electromotive voltage VL of the source side wiring inductance Lss is applied to the input capacitance Ciss, the diode Dr, the resistor Rr, and the impedance Zg. The induced electromotive voltage VL is determined by the drain side wiring inductance Lsd, the source side wiring inductance Lss, the output capacitance Coss of the semiconductor element Q, and the initial value of the cutoff current. The resonance current ir flowing in the feedback circuit 10 by the induced electromotive voltage VL is attenuated by the impedance Zg and the resistance Rr. If a current continues to flow from the induced electromotive voltage VL to the impedance Zg, it becomes difficult for a discharge current for re-off to flow from the input capacitance Ciss to the impedance Zg, and the on-time becomes unnecessarily long.

  FIG. 8 is a waveform diagram for explaining the operation of the equivalent circuit according to FIG. FIG. 8A shows a waveform diagram when the feedback of FIG. 7 is operating stably, and FIG. 8B shows a waveform diagram when the feedback of FIG. 7 is operating unstable. ing.

  FIG. 8B shows a state in which the on-resistance Ron is on for a long time and the low-resistance state continues, and at this time, it can be seen that the resonance current ir vibrates. On the other hand, in FIG. 8A, the on-resistance Ron is turned on for a short time and is in a low resistance state. At this time, the resonance current ir does not oscillate and flows for a moment and converges to zero. ing.

  As described above, when the on-resistance Ron is on for a long time, the resonance current ir does not converge immediately but vibrates for a while. This may be considered that another resonance has occurred in the feedback circuit 10 in FIG. As can be seen from FIG. 8, it is preferable that the semiconductor element Q is turned on for a short period of time without being continued for a long time.

  Here, returning to FIG. 6, since the impedance Zg is a discharge resistance of the input capacitance Ciss, it is normally set to an extremely small value on the assumption that the semiconductor element Q is turned off at high speed. Further, the value of the source side wiring inductance Lss is unclear or varies. Therefore, in the driving circuit 50 for the semiconductor element Q according to the present embodiment, the resistance Rr is appropriately set so as to surely attenuate the resonance current ir, and the on-time of the semiconductor element Q is determined by the vibration of the resonance current ir. However, it is preferable to prevent the switching loss from increasing unnecessarily. That is, the setting is made such that the resonance current ir appropriately attenuates the resonance current ir with the resistor Rr so that the semiconductor element Q is turned on for a moment and then the resonance current ir continues to flow and does not vibrate.

  Returning to FIG. 7, when the induced electromotive voltage VL includes a high frequency component, if the frequency characteristics of the diode Dr are poor, oscillation occurs in the feedback circuit. Therefore, a high speed diode having good frequency characteristics may be used as the diode Dr. preferable. For example, a Schottky barrier diode may be applied to the diode Dr.

  In addition, instead of the resistor Rr, the resistor Rr may be substituted by using the forward voltage drop (VI characteristic) of the diode Dr. Conversely, when the value of the wiring inductance Lss is small and the value of the induced electromotive voltage VL does not store enough energy to charge the input capacitance Ciss, the terminal of the resistor Rr is set so that the wiring inductance Lss becomes large. You may connect to.

  Next, experimental results in which the drive circuit 50a for the semiconductor element Q according to this example is actually applied will be described with reference to FIGS.

  FIG. 9 is an application diagram of the drive circuit 50a for the semiconductor element Q according to the first embodiment which is the subject of the experiment. 1 is substantially the same as the driving circuit 50 of the semiconductor element Q shown in FIG. 1, except that a resistor Rr is inserted and connected between the anode of the diode Dr and the source of the semiconductor element Q in the feedback circuit 10a. This is different from the driving circuit 50 of the semiconductor element Q according to FIG. Further, the gate drive circuit 20 is omitted in the drive circuit 50a of the semiconductor element Q according to FIG. Other components are the same as those of the drive circuit 50 of the semiconductor element Q according to FIG.

  9, in this experiment, the induced electromotive voltage Vs, drain-source voltage Vds, and gate voltage Vgs generated by the high frequency switching noise generated via the snubber capacitor Cs and the output capacitance Coss were evaluated as measurement objects. In addition, since the induced electromotive voltage Vs is induced by switching noise that is a target for reduction, changes in the frequency component and amplitude of the switching noise can be measured by measuring the induced electromotive voltage Vs.

  FIG. 10 is a diagram illustrating a waveform graph of the induced electromotive voltage Vs, the drain-source voltage Vds, and the gate voltage Vgs of the drive circuit 50a of the semiconductor element Q according to the first embodiment illustrated in FIG.

  FIG. 10A is a waveform graph for comparison when the drive circuit 50a for the semiconductor element Q according to the first embodiment is not applied, and is a waveform graph when the feedback circuit 10 of FIG. 9 is not provided. As shown in FIG. 10A, the main component of vibration of the induced electromotive voltage Vs is 75 [MHz], which is higher than the main component 27 [MHz] of vibration of the drain-source voltage Vds. This is because the resonance frequency is determined by the product of the inductance L and the capacitance C of the path, whereas the resonance frequency of the drain-source voltage Vds is mainly determined by the snubber capacitor Cs and the wiring inductances Ls1 and Ls2, and the induced electromotive voltage Vs. This is because the resonance frequency is mainly determined by the output capacitance Coss, the source side wiring inductance Lss, and the drain side wiring inductance Lsd, and the circuit design is performed with Cs> Coss. Thus, it can be seen that when the snubber capacitor Cs is connected separately from the oscillation of the drain-source voltage Vds, high-frequency switching noise is generated via the output capacitance Coss and the wiring inductances Lss and Lsd.

  On the other hand, FIG. 10B shows respective waveforms when the drive circuit 50a for the semiconductor element Q according to the first embodiment is applied. In FIG. 10B, it can be seen that the high frequency components are removed from the waveforms of the induced electromotive voltage Vs and the gate voltage Vgs.

  FIG. 11 is a graph obtained by frequency analysis of the induced electromotive voltage Vs of FIG. In FIG. 11, it can be seen that the high frequency switching noise of 75 [MHz] generated by switching is reduced by applying the driving circuit 50a of the semiconductor element Q according to the present embodiment. In addition, in FIG. 11, the reduction of switching noise can also be confirmed for the 27 [MHz] component. Since the snubber capacitor Cs and the output capacitor Coss are connected in parallel, the resonance current flowing through the snubber capacitor Cs and the wiring inductances Ls1 and Ls2 confirmed by the drain-source voltage Vds actually actually flows into the output capacitor Coss side. The reduction effect on the current is also shown.

  As described above, according to the drive circuit for the semiconductor element Q according to the first embodiment, even when a high-speed switching element such as a power MOSFET is used as the semiconductor element Q, the switching operation can be performed at a high speed with a simple configuration. , Switching noise can be reduced and switching loss can be reduced.

  FIG. 12 is a diagram showing an overall configuration of a drive circuit 50b for a semiconductor device Q according to a second embodiment to which the present invention is applied. In FIG. 12, the drive circuit 50b for the semiconductor element Q according to the second embodiment stores the diode Dr inside the module 30 of the semiconductor element Q, thereby preventing erroneous wiring of the gate drive circuit and an increase in the number of parts. Yes. Since the drive circuit of the semiconductor device according to the present invention has a simple configuration, the diode Dr can be stored inside a module such as a power MOSFET.

  12, in the drive circuit 50b for the semiconductor element Q according to the present embodiment, the semiconductor element Q module 30 includes a drain terminal drain, a gate terminal gate, a signal source terminal source (sig), and a main circuit source terminal source. In addition to (power), an anode terminal anode is provided. The cathode of the diode Dr is connected to the gate of the semiconductor element Q, and the anode is connected to the anode terminal anode. The diode Dr may be a high-speed diode such as a Schottky barrier diode as in the first embodiment.

  On the other hand, a snubber capacitor Cs is connected between the drain terminal drain and the main circuit source terminal source (power) outside the semiconductor element Q module 30, and a resistance is connected between the anode terminal anode and the main circuit source terminal source (power). Rr is connected. Since the cut-off current and switching speed of the semiconductor element Q such as the power MOSFET vary depending on the power converter to be used, the snubber capacitor Cs corresponding to each circuit is often selected. Therefore, in the drive circuit 50b for the semiconductor element Q according to the present embodiment, the snubber capacitor Cs can be variously selected as an external module 30. In addition, since the resistor Rr is designed appropriately according to the snubber capacitor Cs, the resistor Rr is also externally attached, and an appropriate resistor Rr is set according to the selection of the snubber capacitor Cs so that the feedback circuit 10b can be configured. Yes.

  As described above, according to the drive circuit 50b for the semiconductor element Q according to the second embodiment, the diode Dr is stored in the module 30 of the semiconductor element Q to prevent erroneous wiring of the gate circuit and an increase in the number of parts, and Capacitor Cs and resistor Rr leave the degree of freedom of selection, and can suppress an appropriate surge voltage and high-frequency switching noise.

  FIG. 13 is a diagram showing an overall configuration of a drive circuit 50c for a semiconductor device Q according to a third embodiment to which the present invention is applied. In FIG. 13, the driving circuit 50c for the semiconductor device Q according to the third embodiment has the diode Dr stored in the module 30a, and the cathode of the diode Dr is connected to the gate of the semiconductor device Q in the second embodiment. However, the module 30a is not provided with the anode terminal anode, and the anode of the diode Dr is connected to the main circuit source terminal source (power) in the module 30a. It is different. Further, the drive circuit 50c for the semiconductor element Q according to the third embodiment is different from the drive circuit 50b for the semiconductor element Q according to the second embodiment in that the snubber capacitor Cs is stored inside the module 30a. Furthermore, the drive circuit 50c for the semiconductor element Q according to the third embodiment also drives the semiconductor element Q according to the first and second embodiments in that the feedback circuit 10c does not include the resistor Rr connected to the diode Dr. Different from the circuits 50, 50a, 50b.

  Thus, the snubber capacitor Cs may be configured to be stored in the module 30a of the semiconductor element Q. In this case, the module 30a may be designed so that the source side wiring inductance Lss becomes small. As a result, it is not necessary to provide the feedback circuit 10c with a large resistance Rr, and the feedback circuit 10c can be completed within the module 30a by utilizing the on-characteristic (on-resistance) of the diode Dr. Further, the number of components used in the gate drive circuit can be made the same as that of the gate drive circuit without the feedback circuit 10c, and surge voltage and high frequency switching noise can be suppressed without increasing the number of components outside the module 30a. It can be carried out.

  In the drive circuit 50c for the semiconductor element Q according to the third embodiment, the semiconductor element Q may be a semiconductor element Q that can be switched at high speed such as a MOSFET, and the diode Dr may be a high-speed such as a Schottky barrier diode. A diode is preferably applied.

  Thus, according to the drive circuit 50c for the semiconductor element Q according to the third embodiment, the snubber capacitor Cs is integrated and stored in the module 30a, and the feedback circuit 10c is set by setting the source-side wiring inductance Lss small. The resistor Rr required for the above can be substituted with the on-resistance of the diode Dr, and the number of parts of the gate drive circuit can be made the same as that of the gate drive circuit not using the active gate.

  FIG. 14 is a diagram illustrating an overall configuration of a drive circuit 50d for a semiconductor device Q according to a fourth embodiment to which the present invention is applied. In FIG. 14, the drive circuit 50d for the semiconductor element Q according to the fourth embodiment has a circuit configuration in which the snubber capacitor Cs is removed from the drive circuit 50a for the semiconductor element Q according to the first embodiment shown in FIG. Thus, the present invention can also be applied to the drive circuit 50d for the semiconductor element Q not connected to the snubber capacitor Cs. In this case as well, when the semiconductor element Q such as MOSFET is turned off at high speed by high speed switching, the induced electromotive voltage Vs is generated at both ends of the source side wiring inductance Lss by electromagnetic induction. Then, when the resonance current ir flows through the feedback circuit 10a and flows into the gate of the semiconductor element Q via the resistor Rr and the diode Dr, and the electric charge is accumulated in the input capacitance Ciss, the semiconductor element Q is turned on by the rise of the gate voltage Vg. For example, switching noise can be attenuated. Since the individual components are the same as those of the drive circuit 50a for the semiconductor element Q according to FIG. 9 of the first embodiment, the same reference numerals are given and description thereof is omitted.

  FIG. 15 is a diagram illustrating a waveform graph of the induced electromotive voltage Vs and the gate voltage Vgs generated in the source-side wiring inductance Lss of the drive circuit 50d of the semiconductor element Q according to the fourth embodiment. FIG. 15A is a waveform diagram for comparison when the drive circuit 50d of the semiconductor element Q according to the fourth embodiment is not applied, and FIG. 15B is a waveform diagram of the semiconductor element Q according to the fourth embodiment. It is a wave form diagram in case the drive circuit 50d is applied.

  15A is compared with FIG. 15B, the waveform diagram of FIG. 15B to which the drive circuit 50d for the semiconductor element Q according to the present embodiment is applied is the waveform diagram of the semiconductor element Q according to the present embodiment. From the waveform diagram of FIG. 15A in which the drive circuit 50d is not applied, it can be seen that the vibration is suppressed in both Vs and Vgs, and the switching noise attenuation effect is obtained.

  FIG. 16 is a diagram showing a frequency graph obtained by frequency analysis of the induced electromotive voltage Vs shown in FIG. Also in FIG. 16, the frequency characteristic to which the drive circuit 50 d for the semiconductor element Q according to the present embodiment is applied is less suppressed than the frequency characteristic to which the drive circuit 50 d for the semiconductor element Q according to the present embodiment is not applied. It can be seen that switching noise is suppressed.

  Thus, according to the drive circuit 50d for the semiconductor element Q according to the fourth embodiment, the switching noise at the time of turn-off can be suppressed in the drive circuit 50d for the semiconductor element Q that does not have the snubber capacitor Cs. Low loss turn-off can be performed.

  The preferred embodiments of the present invention have been described in detail above. However, the present invention is not limited to the above-described embodiments, and various modifications and substitutions can be made to the above-described embodiments without departing from the scope of the present invention. Can be added.

1 is an overall configuration diagram of a drive circuit 50 for a semiconductor device according to Embodiment 1. FIG. FIG. 6 is a diagram illustrating operation waveforms of the drive circuit 50 of the semiconductor element Q according to the first embodiment. FIG. 2A is a diagram showing a conventional operation waveform to be compared. FIG. 2B is a diagram illustrating operation waveforms of the drive circuit 50 for the semiconductor element Q according to the first embodiment. 5 is a diagram illustrating a drive circuit 150 of a semiconductor element Q according to a comparative example of the drive circuit 50 of the semiconductor element Q according to Example 1. FIG. It is the figure which showed the operation | movement waveform of the drive circuit 150 of the semiconductor element Q which concerns on a comparative example. FIG. 4A is an operation waveform diagram when the snubber capacitor Cs is not provided. FIG. 4B is an operation waveform diagram when the snubber capacitor Cs is present. It is a high frequency equivalent circuit schematic of the drive circuit 150 of the semiconductor element Q concerning a comparative example. FIG. 6 is an equivalent circuit diagram for explaining an operation at the time of feedback of the drive circuit 50 of the semiconductor element Q according to the first embodiment. FIG. 5 is an equivalent circuit diagram for explaining in detail an operation at the time of feedback of the drive circuit 50 of the semiconductor element Q according to the first embodiment. FIG. 8 is a waveform diagram for explaining the operation of the equivalent circuit according to FIG. 7. FIG. 8A is a waveform diagram during the feedback stable operation. FIG. 8B is a waveform diagram during an unstable feedback operation. It is an application figure of the drive circuit 50a of the semiconductor element Q concerning Example 1 to be tested. 4 is a waveform diagram of a drive circuit 50a for a semiconductor device Q according to Example 1. FIG. FIG. 10A is a waveform diagram when the drive circuit 50a for the semiconductor element Q according to the first embodiment is not applied. FIG. 10B is a waveform diagram when the drive circuit 50a for the semiconductor element Q according to the first embodiment is applied. It is the graph which analyzed the frequency of the induced electromotive voltage Vs of FIG. FIG. 6 is an overall configuration diagram of a drive circuit 50b for a semiconductor element Q according to a second embodiment. FIG. 10 is an overall configuration diagram of a drive circuit 50c for a semiconductor element Q according to Example 3. FIG. 10 is an overall configuration diagram of a drive circuit 50d for a semiconductor element Q according to a fourth embodiment. FIG. 10 is a waveform graph of a drive circuit 50d for a semiconductor element Q according to Example 4. FIG. 15A is a waveform diagram when the drive circuit 50d for the semiconductor element Q according to the fourth embodiment is not applied. FIG. 15B is a waveform diagram when the drive circuit 50d for the semiconductor element Q according to the fourth embodiment is applied. FIG. 16 is a frequency graph obtained by frequency analysis of the induced electromotive voltage Vs of FIG. 15.

Explanation of symbols

10, 10a, 10b, 10c Feedback circuit 20 Gate drive circuit 30, 30a Module 50, 50a, 50b, 50c, 50d Semiconductor element drive circuit Q Semiconductor element Dr Diode Rr Resistance Ron On resistance (variable resistance)
Cs Snubber capacitor Lsd Drain side wiring inductance Lss Source side wiring inductance Ls1, Ls2 Wiring inductance Ciss Input capacity Coss Output capacity S1, S2 Switch drain Drain terminal gate Gate terminal source (sig) Signal source terminal source (power) Main circuit source terminal anode anode terminal

Claims (8)

A drive circuit for a semiconductor element,
A cathode of a diode is connected to the gate of the semiconductor element, and an anode of the diode is connected to a source of the semiconductor element;
A drive circuit for a semiconductor element, comprising a feedback circuit in which a resistor is inserted and connected between the gate and the cathode or between the source and the anode.   2. The semiconductor element driving circuit according to claim 1, wherein the semiconductor element is a semiconductor element having a unipolar structure.   3. The semiconductor element drive circuit according to claim 1, wherein the semiconductor element is a MOSFET.   4. The semiconductor element driving circuit according to claim 1, wherein the diode is a Schottky barrier diode or a high-speed diode having an operation speed higher than that of the Schottky barrier diode.   5. The resistor according to claim 1, wherein when the semiconductor element is switched off, the current supplied to the gate by the feedback circuit is set to a magnitude that does not cause oscillation. A drive circuit for a semiconductor device according to claim 1.   6. The semiconductor element driving circuit according to claim 1, wherein a snubber capacitor is connected between the drain and the source of the semiconductor element. The semiconductor element and the diode are accommodated in a module,
7. The semiconductor element driving circuit according to claim 6, wherein the resistor and the snubber capacitor are provided outside the module. A drive circuit for a semiconductor device housed in a module,
A feedback circuit in which a cathode of a diode is connected to a gate of the semiconductor element, and an anode of the diode is connected to a source of the semiconductor element;
The on-resistance of the diode is set to a magnitude that does not cause oscillation of the current supplied to the gate by the feedback circuit when the semiconductor element is switched off.

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