JP2016169727A - Semiconductor device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent a spark plug from performing erroneous ignition at the time of self-shutdown.SOLUTION: When a self-shutdown signal source 211 detects a normal state and a transistor M3 is in ON state, upon ON signal is received at IN terminal, a transistor M1 is ON, the transistor M2 is OFF and IGBT 24 is ON. At this time, when the self-shutdown signal source 211 detects an abnormal state, the transistor M1 is OFF and the transistor M2 is ON, a gate terminal of IGBT 24 is connected to the emitter terminal through the transistors M2, M3 to cause electric charge charged in a gate capacity to be discharged rapidly. With this arrangement, when a comparator 216 detects that a collector voltage of IGBT 24 is increased and becomes higher than a prescribed voltage, the transistor M3 becomes OFF and a gradual shut-down is carried out in such a way that the electrical charge of the gate capacity is gradually discharged by a resistor 213.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a semiconductor device used for an ignition device of an internal combustion engine for automobiles, and more particularly to a semiconductor device having a function of performing self-shutdown when an abnormality occurs.

  2. Description of the Related Art An ignition device for an internal combustion engine for automobiles mainly includes an ignition coil that generates a high voltage, and an ignition integrated circuit that controls switching of a primary current of the ignition coil (hereinafter, the integrated circuit is referred to as an IC (Integrated Circuit)). A spark plug. The ignition IC includes a power semiconductor element connected in series to the primary coil of the ignition coil and a drive for driving the power semiconductor element based on a signal from an engine control unit (hereinafter referred to as ECU (Engine Control Unit)). Circuit. The ignition IC also includes a self-interruption circuit that turns off the power semiconductor element and interrupts the current flowing through the ignition coil when any abnormality occurs in the ignition IC or the power semiconductor element. Examples of the abnormality in the ignition IC and the power semiconductor element include an abnormality in which the drive circuit continuously energizes the power semiconductor element over a predetermined time and an abnormality in which the power semiconductor element is overheated.

  When such abnormality is detected, the self-cutoff circuit cuts off the current flowing in the ignition coil by turning off the power semiconductor element. For this reason, the current flowing through the ignition coil changes abruptly regardless of the signal from the ECU, and as a result, the secondary voltage of the ignition coil changes abruptly, and the spark plug discharges at a time other than the normal timing. May end up. In this case, the engine may break due to abnormal combustion.

  On the other hand, when an abnormality is detected and self-shutoff is performed, the change in the primary side current of the ignition coil is gently shut off to prevent the spark plug from being erroneously discharged at any timing. Off control is known (see, for example, Patent Documents 1 and 2).

  In the technique of Patent Document 1, a resistor and a constant current circuit are connected to the gate terminal of the power semiconductor element so that the gate voltage that is on-controlled when an abnormality is detected is gradually reduced. In the technique of Patent Document 2, the gate voltage of the power semiconductor is gradually decreased by controlling the self-cutting transistor with the output of the integrating circuit constituted by the reverse leakage resistance of the diode and the capacitor. As described above, by executing the gentle shut-off that gradually decreases the gate voltage of the power semiconductor element, the change in the primary side current of the ignition coil becomes gentle, and as a result, the change in the secondary side current of the ignition coil also becomes gentle. Thus, abnormal ignition of the spark plug can be prevented.

Here, a specific configuration example of the ignition IC having the above-described self-blocking function will be described.
FIG. 19 is a diagram illustrating an ignition device for an automobile internal combustion engine including a configuration example of a conventional ignition IC, and FIG. 20 is a diagram illustrating an example of operation waveforms of the ignition IC of a conventional automotive internal combustion engine.

  As shown in FIG. 19, the ignition device for an internal combustion engine for automobiles has an ECU 1 for controlling the whole ignition device, an ignition IC 2 constituting an igniter, and a primary coil 31 and a secondary coil 32 wound around an iron core. An ignition coil 3, a power source (battery) 4, and a spark plug 5 are provided. In the ignition IC 2, an insulated gate bipolar transistor (hereinafter referred to as IGBT (Insulated Gate Bipolar Transistor)) 24 is used as a power semiconductor element that controls on / off of the primary current of the ignition coil 3.

  The ignition IC 2 is connected to a C terminal (collector terminal) connected to the ignition coil 3, an E terminal (emitter terminal) connected to the ground potential, an IN terminal (input terminal) connected to the ECU 1, and the power supply 4. It has a B terminal (power supply terminal).

  The C terminal of the ignition IC 2 is connected to one terminal of the primary coil 31 of the ignition coil 3, and the other terminal of the primary coil 31 is connected to the positive terminal of the power source 4. The E terminal of the ignition IC 2 is connected to the ground. The secondary coil 32 of the ignition coil 3 has one terminal connected to one electrode of the spark plug 5, and the other terminal connected to the positive terminal of the power source 4. The other electrode of the spark plug 5 and the negative terminal of the power source 4 are each connected to the ground.

  The ignition IC 2 also includes a drive circuit 22 that drives the IGBT 24, a self-cutoff circuit 21, and a power supply circuit 23. The drive circuit 22 includes a NAND circuit 221, a transistor M1 as a gate pull-up circuit, and a transistor M2 as a gate pull-down circuit. Here, the transistor M1 is a p-type MOSFET (Metal-Oxide-Semiconductor Field-Effect Transistor), and the transistor M2 is an n-type MOSFET, and each has a switch function. One input terminal of the NAND circuit 221 is connected to the IN terminal, and the output terminal of the NAND circuit 221 is connected to gate terminals which are control terminals of the transistors M1 and M2 constituting the inverter by a complementary circuit. . The drain terminals of the transistors M1 and M2 are connected to the gate terminal of the IGBT 24. The source terminal of the transistor M 1 is connected to the output terminal of the power supply circuit 23.

  The power supply circuit 23 converts the voltage of the power supply 4 (for example, 14 volts (V)) into a voltage (for example, 5 V) that is stepped down, and serves as a power supply for the drive circuit 22 and the self-cutoff circuit 21.

  The self-cutoff circuit 21 includes a self-cutoff signal source 211, an inverter 212, a transistor M3 configured by an n-type MOSFET and functioning as a switch circuit, and a resistor 213. The self-interruption signal source 211 is an abnormality detection circuit that detects an abnormality in the energization state of the IGBT 24 and has, for example, a timer function and a temperature detection function that detect abnormal energization and overheating of the IGBT 24. The output terminal of the self-cutoff signal source 211 is connected to the input terminal of the inverter 212, and the output terminal of the inverter 212 is connected to the other input terminal of the NAND circuit 221 of the drive circuit 22 and the gate terminal of the transistor M3. The drain terminal of the transistor M3 is connected to the source terminal of the transistor M2 of the drive circuit 22, and the source terminal of the transistor M3 is connected to the E terminal of the ignition IC 2. The resistor 213 has one terminal connected to the gate terminal of the IGBT 24, the other terminal connected to the E terminal of the ignition IC 2, and constitutes a minute current circuit that draws out the charge charged in the gate capacitance of the IGBT 24. .

  Here, the operation of the ignition device for an automobile internal combustion engine will be described with reference to FIGS. 19 and 20. The ECU 1 outputs a signal Vin for controlling on / off of the IGBT 24 to the IN terminal of the ignition IC 2. For example, when the IGBT 24 is on-controlled, the ECU 1 outputs an on signal with a voltage of Vin = 5 V (H level) to the IN terminal. When the IGBT 24 is controlled to be off, the ECU 1 outputs an off signal having a voltage of Vin = 0 V (L level) to the IN terminal. The self-shutoff signal s1 output from the self-shutdown signal source 211 of the self-shutdown circuit 21 is Vs1 = L level during normal operation and Vs1 = H level during abnormal operation. Therefore, during normal operation, the self-interruption signal s1 is inverted by the inverter, and an H level signal is supplied to the other input terminal of the NAND circuit 221 and the gate terminal of the transistor M3. For this reason, the NAND circuit 221 operates as an inverter with respect to the signal input from the ECU 1, and the transistor M3 is normally on-controlled.

  First, when an ON signal is input to the IN terminal of the ignition IC 2, the output of the NAND circuit 221 becomes L level, the transistor M1 is turned on, and the transistor M2 is turned off. Thereby, the drive circuit 22 pulls up the gate voltage Vg of the gate terminal of the IGBT 24 to 5 V, and turns on the IGBT 24. As a result, a collector current (hereinafter referred to as Ic) starts to flow from the power source 4 to the C terminal of the ignition IC 2 via the primary coil 31 of the ignition coil 3. The collector current Ic is determined as dIc / dt by the inductance of the primary coil 31 and the applied voltage, and is a constant current value (for example, 17 amperes) determined by the resistance of the primary coil 31, the on-resistance of the IGBT 24, and the voltage of the power source 4. A)). The collector voltage at the C terminal of the ignition IC 2 (hereinafter referred to as Vc. Note that the collector voltage Vc referred to here is the collector voltage Vc for simplicity of the collector-emitter voltage). Is turned on and the collector current Ic begins to flow, the voltage of the applied power supply 4 is momentarily reduced, and thereafter gradually increases due to the on-resistance of the IGBT 24.

  Next, when an off signal is input to the IN terminal of the ignition IC 2, the output of the NAND circuit 221 becomes H level, the transistor M 1 is turned off, and the transistor M 2 is turned on. As a result, the drive circuit 22 pulls down the gate voltage Vg of the gate terminal of the IGBT 24 to 0 V and turns off the IGBT 24. Thereby, the collector current Ic decreases rapidly, and the collector voltage Vc increases rapidly. Due to the rapid change in the collector current Ic, the voltage across the primary coil 31 increases rapidly. At the same time, the voltage across the secondary coil 32 also increases rapidly (for example, increases to 30 kV), and the voltage is applied to the spark plug 5. The spark plug 5 is discharged when the applied voltage is about 10 kV or more. Thereafter, the collector voltage Vc returns to the voltage of the power supply 4. The above is the operation in the range indicated by “normal” in FIG.

  Next, when the ON signal of the ECU 1 is output longer than a predetermined time, or the ignition IC 2 or the IGBT 24 is overheated, there is a possibility that the ignition coil 3 or the ignition IC 2 may be broken down. The circuit 21 operates to cut off the collector current Ic. However, if the collector current Ic is suddenly cut off, the spark plug 5 may be discharged at a timing other than the setting, and the engine may be damaged. For this reason, the self-cutoff circuit 21 needs to control | dIc / dt | within a range in which the spark plug 5 is not erroneously discharged (for example, a current change of about 1 A / ms (millisecond)).

  Next, a case where an abnormality occurs will be described. Even in this case, initially, the gate voltage Vg, the collector current Ic, and the collector voltage Vc of the IGBT 24 behave in the same manner as in the normal case. The gate voltage Vg becomes an H level signal, the collector current Ic rises to a predetermined current value and is maintained at a constant value (for example, 17 A), and the collector voltage Vc gradually rises.

  Here, when the timer circuit (not shown) measures the length of the ON signal longer than a predetermined time, or when the temperature detection circuit (not shown) detects overheating, the self-cutoff signal source 211 is H level indicating an abnormality. A self-shutoff signal s1 is output. When the self-cutoff signal source 211 outputs a self-cutoff signal s1 at H level (in FIG. 20, Vs1 = H level signal), an L level signal is sent through the inverter 212 to the other input terminal of the NAND circuit 221 and the transistor M3. Are respectively applied to the gate terminals. As a result, the output terminal of the NAND circuit 221 is fixed to an H level signal, the transistor M1 is turned off, and the transistor M2 is turned on. At this time, since the transistor M3 connected in series with the transistor M2 is turned off in response to the L level gate signal, the charge charged in the gate capacitance of the IGBT 24 is gradually discharged through the resistor 213. It will be. As a result, when the gate voltage Vg of the IGBT 24 gradually decreases to a predetermined voltage or less, the collector current Ic starts to decrease and the collector voltage Vc starts to increase.

  Thus, for example, when an abnormality occurs in which the signal Vin of the ECU 1 is fixed on, the gate voltage Vg of the IGBT 24 is constant after the self-cutoff signal source 211 outputs the self-cutoff signal s1 at the H level. Decreases with speed. When the gate voltage Vg of the IGBT 24 decreases to a predetermined voltage, the collector current Ic begins to decrease gradually, and a gentle interruption is performed.

JP 2008-45514 JP 2006-37822 A

  In the ignition IC 2, as described above, after the self-interruption signal s 1 is output, the charge charged in the gate capacitance of the IGBT 24 is gradually discharged, and the gate voltage Vg decreases at a constant rate. Along with this, the collector current Ic decreases, but the method of the decrease is not constant due to the electrical characteristics of the IGBT. That is, the collector current Ic decreases only slightly until the gate voltage Vg decreases to some extent, and the collector current Ic decreases greatly after the gate voltage Vg decreases to a certain extent. In other words, the time until the gate voltage Vg decreases to some extent is like a delay time until the collector current Ic starts to decrease effectively. During the delay time, a constant large current (for example, a current close to 17 A) continues to flow through the IGBT 24 and the primary coil 31, and there is a risk of damage such as thermal destruction. In order to avoid this, it is necessary to increase the error detection sensitivity by shortening the timer time considering the delay time, lowering the temperature of overheating detection, etc., but in this case, there is a problem that self-blocking tends to occur. is there. Moreover, even if a large current flows during the delay time, it is necessary to reduce the thermal resistance of the ignition IC 2 in order to suppress the heat generated by the large current. In this case, it is necessary to increase the chip size.

  The present invention has been made in view of the above points, and shortens the delay time until the current that actually flows through the primary coil starts to decrease during self-shutdown, thereby reducing the power semiconductor element and the primary coil of the ignition coil. An object is to provide a semiconductor device in which heat generation is suppressed.

  In order to solve the above-described problems, the present invention provides a semiconductor device that performs switching control of a power semiconductor element. This semiconductor device is connected to a gate terminal of a power semiconductor element and pulls up the gate terminal based on an input signal, and is connected to the gate terminal of the power semiconductor element, and the gate terminal is connected based on an input signal. A gate pull-down circuit for pulling down, an abnormality detection circuit for detecting an abnormality in the energization state of the power semiconductor element, a micro current circuit connected to the gate terminal of the power semiconductor element, and extracting a charge from the gate capacitance of the power semiconductor element, and the power semiconductor A voltage detection circuit connected to the collector terminal of the element to detect the collector voltage; and a switch circuit connected between the gate pull-down circuit and the emitter terminal of the power semiconductor element. When the abnormality detection circuit detects an abnormality, the gate pull-up circuit is shut off, the gate pull-down circuit is turned on, the charge is extracted from the gate capacitance of the power semiconductor element via the switch circuit, and the collector voltage rises due to the extraction of the charge. When the voltage detection circuit detects that the set value has been exceeded, the switch circuit is shut off and the charge is extracted by the minute current circuit.

  According to such a semiconductor device, when the abnormality detection circuit detects an abnormality, first, the power semiconductor element is quickly turned off, and when the collector voltage is about to rise, a gentle interruption is performed. Thereby, the delay time until actually starting the gentle shut-off can be shortened as compared with the case where the soft shut-off is started immediately after the abnormality detection circuit detects the abnormality.

  In the semiconductor device having the above configuration, when an abnormality occurs, since the rapid shutoff is started after the quick shutoff, the delay time until the slow shutoff is started can be shortened, so that the heat generated during the delay time is suppressed. Will be able to.

It is a figure which shows the ignition device of the internal combustion engine for motor vehicles containing the structural example of IC for ignition which concerns on 1st Embodiment. It is a figure which shows the example of an operation waveform of IC for ignition of the internal combustion engine for motor vehicles. It is a current-voltage characteristic diagram of IGBT. It is a time chart which shows transition of the operating point at the time of self interruption. It is a circuit diagram which illustrates the composition of a self-cutting signal source. It is a figure which shows the operation | movement waveform of a reset circuit. It is a figure which shows the operation | movement waveform of a self interruption | blocking signal source. It is a figure which shows the ignition device of the internal combustion engine for motor vehicles containing the structural example of IC for ignition which concerns on 2nd Embodiment. It is a figure which shows the ignition device of the internal combustion engine for motor vehicles containing the structural example of IC for ignition which concerns on 3rd Embodiment. It is a figure which shows the ignition device of the internal combustion engine for motor vehicles containing the structural example of IC for ignition which concerns on 4th Embodiment. It is a figure which shows the modification of the ignition device of the internal combustion engine for motor vehicles containing the structural example of IC for ignition which concerns on 4th Embodiment. It is a figure which shows the ignition device of the internal combustion engine for motor vehicles containing the structural example of IC for ignition which concerns on 5th Embodiment. It is a figure which shows the ignition device of the internal combustion engine for motor vehicles containing the structural example of IC for ignition which concerns on 6th Embodiment. It is a figure which shows the ignition device of the internal combustion engine for motor vehicles containing the structural example of IC for ignition which concerns on 7th Embodiment. It is a figure which shows the ignition device of the internal combustion engine for motor vehicles containing the structural example of IC for ignition which concerns on 8th Embodiment. It is a figure which shows the ignition device of the internal combustion engine for motor vehicles containing the structural example of IC for ignition which concerns on 9th Embodiment. It is a figure which shows the ignition device of the internal combustion engine for motor vehicles containing the structural example of IC for ignition which concerns on 10th Embodiment. It is a figure which shows the ignition device of the internal combustion engine for motor vehicles containing the structural example of IC for ignition which concerns on 11th Embodiment. It is a figure which illustrates the ignition device of the internal combustion engine for motor vehicles containing the structural example of conventional IC for ignition. It is a figure which shows the example of an operation waveform of ignition IC of the conventional internal combustion engine for motor vehicles.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings, taking as an example a case where the present invention is applied to an ignition control IC used in an ignition device for an automobile internal combustion engine and having a self-cutoff function. In the following description, the same or equivalent components as those shown in FIG. 19 are given the same reference numerals, and detailed descriptions thereof are omitted. In addition, each embodiment can be implemented by combining a plurality of embodiments within a consistent range.

  FIG. 1 is a diagram showing an ignition device for an internal combustion engine for an automobile including an example of the configuration of an ignition IC according to the first embodiment. FIG. 2 is a diagram showing an example of operation waveforms of the ignition IC for the internal combustion engine for an automobile. 3 is a current / voltage characteristic diagram of the IGBT, and FIG. 4 is a time chart showing the transition of the operating point at the time of self-shutoff.

  In the ignition IC 2 according to the first embodiment, as shown in FIG. 1, the configuration of the self-cutoff circuit 21 is changed as compared with that shown in FIG. 19. In other words, the reference voltage circuit 215, the comparator 216, the NAND circuit 217, the resistors 218 and 219, and the Zener diode 220 are added to the self-cutoff circuit 21. Note that the power supply circuit 23 is a power supply for the drive circuit 22 and the self-cutoff circuit 21 as in the case shown in FIG.

  The output terminal of the reference voltage circuit 215 is connected to the inverting input terminal of the comparator 216, and the output terminal of the comparator 216 is connected to one input terminal of the NAND circuit 217. The other input terminal of the NAND circuit 217 is connected to the output terminal of the self-cutoff signal source 211, and the output terminal of the NAND circuit 217 is connected to the gate terminal of the transistor M3. The resistor 218 has one terminal connected to the C terminal of the ignition IC and the other terminal connected to one terminal of the resistor 219. The other terminal of the resistor 219 is connected to the E terminal of the ignition IC. A connection point between the resistor 218 and the resistor 219 is connected to a non-inverting input terminal of the comparator 216 and further connected to a cathode terminal of the Zener diode 220. The anode terminal of the Zener diode 220 is connected to the E terminal of the ignition IC.

  The resistors 218 and 219 connected in series constitute a voltage dividing circuit, for example, have the same resistance value, and output a voltage value (Vc / 2) that is 50% of the collector voltage Vc at the C terminal. The reference voltage circuit 215 outputs a predetermined reference voltage Vref. Thus, the resistors 218 and 219, the reference voltage circuit 215, the comparator 216, and the NAND circuit 217 constitute a voltage detection circuit for the collector voltage Vc. Here, the comparator 216 outputs a signal s2 (a signal of Vs2 = H level in FIG. 2) when the collector voltage Vc exceeds a predetermined value corresponding to the reference voltage Vref.

  The collector voltage Vc is not detected directly by the comparator 216 but is divided and detected by the resistors 218 and 219. The collector voltage Vc is higher than the withstand voltage of the comparator 216. This is so that the detection operation can be performed even in the event of a failure. The Zener diode 220 is provided for protecting the circuit of the comparator 216 and the like, and protects the circuit of the comparator 216 and the like even when the collector voltage Vc becomes higher than the withstand voltage of the comparator 216. The reverse withstand voltage of the Zener diode 220 is set such that the collector voltage Vc is larger than a predetermined value corresponding to the reference voltage Vref.

  In the above configuration, when the self-shutoff signal source 211 does not output the self-shutdown signal s1, that is, in a normal operation in which a signal of Vs1 = L level is output in FIG. 19 and the same operation as described with reference to FIG.

  Next, for example, the self-cutoff signal source 211 detects an abnormality in which the IGBT 24 is fixed in the ON state, and continuously outputs the self-cutoff signal s1 (in FIG. 2, a signal of Vs1 = H level is output). The operation when doing this will be described. In this case, immediately after the ON signal (Vin = H level signal) is input from the ECU 1, the same operation as the normal operation is performed. If the ON signal is continuously input, the collector current Ic eventually increases to a predetermined current value and is maintained at a constant value (for example, 17A), and the collector voltage Vc gradually increases accordingly. And become constant.

  Here, when the H-level self-cutoff signal s 1 is output from the self-cutoff signal source 211, the L-level signal is input to the NAND circuit 221 through the inverter 212. Therefore, the NAND circuit 221 outputs an H level signal, turns off the transistor M1, and turns on the transistor M2. At this time, in the self-cutoff circuit 21, the self-cutoff signal source 211 outputs the H level signal Vs1, but since the collector voltage Vc has not reached the predetermined value corresponding to the reference voltage Vref, the transistor M3 is turned on. It remains. Since the transistors M2 and M3 are on, the charge charged in the gate capacitance of the IGBT 24 is discharged through the transistors M2 and M3, and the gate voltage Vg of the IGBT 24 rapidly decreases, and accordingly, the collector voltage Vc. Rises rapidly.

  When the collector voltage Vc rises above a predetermined value, the output terminal of the comparator 216 outputs an H level signal Vs2, thereby turning off the transistor M3. Thereafter, the operation shifts to a gentle shut-off operation in which the charge charged in the gate capacitance of the IGBT 24 is discharged through the resistor 213.

  As described above, in the ignition IC 2, when the self shut-off circuit 21 detects an abnormality and performs self shut-off, first, the same quick shut-off as the normal shut-off is performed, and then when the collector voltage Vc exceeds a certain value, the soft shut-off is performed. Like to do. For this reason, since the delay time from the occurrence of abnormality to the start of the gentle shut-off is extremely short, heat generated in the IGBT 24 and the ignition coil 3 during that time can be suppressed.

  Next, the reason why the quick shut-off is possible until the gentle shut-off is started will be described. First, the current / voltage characteristics of the IGBT 24 having a general output characteristic as a power semiconductor element of the ignition IC 2 are shown in FIG. In FIG. 3, the vertical axis indicates the collector current Ic and the horizontal axis indicates the collector voltage Vc, and shows the relationship between the collector current Ic and the collector voltage Vc when the gate voltage Vg is changed. FIG. 3 also shows the load line of the ignition coil 3. This load line is, for example, a load line when the power source 4 is 14 V and the resistance of the primary coil 31 is 0.7 ohm (Ω). The intersection of the load line and the current / voltage curve is the operating point of the IGBT 24. For example, when the gate voltage Vg is 5V, the collector current Ic is 17A and the collector voltage Vc is 2V. The operating point when the load is interrupted moves from the Vg = 5V to the gate threshold voltage of 2V in the lower right direction on the load line as Vg decreases.

  Since the IGBT 24 is operated by changing the gate voltage Vg, the time chart of FIG. 4 shows the image of the gate voltage Vg decreasing at a constant speed on the load line. The image of the gate voltage Vg decreasing at a constant speed corresponds to discharging the charge of the gate capacitance by the resistor 213 during self-shutoff as in the case of the circuit of FIG. In FIG. 4, the vertical axis represents the gate voltage Vg and the collector current Ic, the horizontal axis represents time, the time change of the gate voltage Vg is indicated by a broken line, and the time change of the collector current is indicated by a solid line. According to FIG. 4, the collector current Ic decreases about 1 A from the time t1 to the time t2 when the self-shutoff starts, that is, until the gate voltage Vg decreases from 5V to 3.2V. Further, the collector current Ic is reduced by approximately 16 A from the time t2 to the time t3 when the gate voltage Vg is reduced from 3.2V to 2V.

  Here, let us consider | dIc / dt | <1 A / ms, which is a condition of time variation of the collector current Ic at which the spark plug 5 does not ignite at the time of self-shutoff. From time t1 to time t2, it takes 24 ms for the collector current Ic to decrease by 1 A, and from time t2 to time t3, it takes 16 ms for the collector current Ic to decrease by 16 A. That is, the rate of decrease in the collector current Ic from time t2 to time t3 substantially satisfies the above-mentioned conditions, but it takes too much time from time t1 to time t2. The time corresponds to the delay time shown in FIG. This means that the time required for the collector current Ic to decrease by 1 A can be shortened to approximately 1 ms.

In the present invention, the time (t1-t2) in which the collector current Ic decreases from 17A to 16A is shortened, and the delay time shown in FIG. 20 is substantially eliminated.
In order to explain this, in the IV characteristics of a power semiconductor with a load set, a range in which the change in the collector current Ic with respect to the change in the gate voltage Vg is as small as the range is defined as follows. That is, the gate voltage Vg decreases and the gate voltage that shifts from the small range to the large range, the collector voltage corresponding to the gate voltage, and the collector current corresponding to the gate voltage are respectively expressed as the gate voltage threshold Vgth and the collector voltage. It is assumed that the threshold value Vcth and the collector current threshold value Icth.

  This will be described with reference to a specific example. In FIG. 4, the collector voltage and the gate voltage at time t2 correspond to the collector voltage threshold Vcth and the gate voltage threshold Vgth, respectively. Between time t1 and t2, a change in the collector current Ic with respect to the change in the gate voltage Vg corresponds to a small range, and between time t2 and time t3 corresponds to a range in which the change in the collector current Ic with respect to the change in the gate voltage Vg. . Note that the collector voltage Vc increases as the gate voltage Vg decreases.

  In the first embodiment, after the H-level self-cutoff signal s1 is output from the self-cutoff signal source 211, the collector voltage Vc is rapidly cut off until the collector voltage Vc reaches the collector voltage threshold value Vcth. After the collector voltage threshold value Vcth is exceeded, a gentle shut-off is performed. For this purpose, the values of the resistors 218 and 219 that determine the voltage division of the collector voltage Vc and the reference voltage Vref are set so as to detect whether the collector voltage Vc exceeds or does not exceed the collector voltage threshold value Vcth. is there. That is, when the collector voltage Vc reaches the collector voltage threshold value Vcth, the voltage appearing at the connection point between the resistor 218 and the resistor 219 is set to the reference voltage Vref. This is because after setting the reference voltage Vref, that is, when the collector voltage Vc becomes the collector voltage threshold value Vcth, the voltage appearing at the connection point of the resistor 218 and the resistor 219 becomes the reference voltage Vref. A value of 219 may be set.

  In other words, the collector current Ic corresponding to the time t2 is detected as a value converted to the collector voltage Vc based on the current / voltage characteristics of FIG. 3, and is rapidly shut off until the converted value is detected from the start of self-shutdown. After the conversion value is detected, a gentle shut-off is performed. Specifically, in the example of FIG. 3, the value of the collector voltage Vc on the load line when the collector current Ic is 16 A is about 2.4V. For this reason, the voltage dividing ratio by the resistors 218 and 219 and the reference voltage Vref of the reference voltage circuit 215 are set so that the comparator 216 outputs the H level voltage Vs2 when the collector voltage Vc = 2.4V. In the above example, since the voltage dividing ratio is ½, the reference voltage Vref is about 1.2V.

  Note that the reference voltage Vref is desirably set sufficiently higher than the noise level so that the comparator 216 does not malfunction due to the noise voltage. The reference voltage Vref is smaller than the voltage supplied from the power supply circuit 23.

  The control according to the first embodiment uses the phenomenon that the collector voltage Vc suddenly rises after the IGBT 24 is turned on and reaches a pinch-off state where the collector current Ic is saturated, and the collector voltage starts to rise. This is also the control that starts the gentle shut-off.

FIG. 5 is a circuit diagram illustrating the configuration of the self-cutoff signal source, FIG. 6 is a diagram showing the operation waveform of the reset circuit, and FIG. 7 is a diagram showing the operation waveform of the self-cutoff signal source.
The self-cutoff signal source 211 includes a reset circuit 6 and a latch circuit 7. In the reset circuit 6, resistors 61 and 62 are connected in series between the IN terminal and the E terminal, and a common connection point of the resistors 61 and 62 is connected to one terminal of the resistor 65 via the inverters 63 and 64. ing. The other terminal of the resistor 65 is connected to one terminal of the capacitor 66, and the other terminal of the capacitor 66 is connected to the E terminal. The other terminal of the resistor 65 is also connected to the input terminal of the inverter 67, and the output terminal of the inverter 67 constitutes an output terminal that outputs the reset signal R of the reset circuit 6. As for the reset circuit 6, an ON signal (Vin = H level signal) input from the ECU 1 to the IN terminal is a power source for the inverters 63, 64, and 67.

  The latch circuit 7 includes four NOR circuits 71, 72, 73, and 74 and is configured to be supplied with power from the power supply circuit 23. Here, the NOR circuits 73 and 74 constitute an RS flip-flop circuit, and the NOR circuits 71 and 72 constitute a circuit that shapes the set signal of the RS flip-flop circuit. That is, the output terminal of the NOR circuit 73 is connected to one input terminal of the NOR circuit 74, the output terminal of the NOR circuit 74 is connected to one input terminal of the NOR circuit 73, and the other input terminal of the NOR circuit 74 is The output terminal of the reset circuit 6 is connected. The output terminal of the NOR circuit 74 is connected to the output terminal that outputs the self-cutoff signal s 1, and the other input terminal of the NOR circuit 73 is connected to the output terminal of the NOR circuit 72. One input terminal of the NOR circuit 72 is connected to the output terminal of the NOR circuit 71, and the other input terminal of the NOR circuit 72 is connected to a terminal to which the NOR circuit 74 inputs a reset signal. The NOR circuit 71 has input terminals 71a and 71b. Although not shown, a timer circuit and a temperature detection circuit are connected to the input terminals 71a and 71b. The timer circuit receives an H level signal when an ON signal (Vin = H level signal) input from the ECU 1 to the IN terminal is continuously input even after a predetermined time. In addition, an H level signal is input from the temperature detection circuit when the temperature of the IGBT 24 or the ignition IC 2 exceeds a predetermined temperature.

  In the self-cutoff signal source 211 configured as described above, the reset circuit 6 outputs the reset signal R a predetermined time after the ON signal (Vin = H level signal) is input to the IN terminal. The operation of the reset circuit 6 when the on signal is input to the IN terminal and the voltage Vin rises is shown in FIG. In FIG. 6, the threshold voltages of the inverters 63, 64, and 67 are indicated by Vthinv, the resistance values of the resistors 61 and 62 are indicated by R61 and R62, and the output voltages of the inverters 63, 64, and 67 are indicated by Vout63, Vout64, and Vout67.

  Here, all the inverters 63, 64, and 67 output a voltage equal to the voltage Vin until time t12 when the ON signal is input at time t11 and the voltage Vin reaches the threshold voltage Vthinv of the inverters 63, 64, and 67. To do.

  Next, when the voltage Vin is between Vthinv and Vthinv × (R61 + R62) / R62 (time t12-t13), the output voltage Vout63 of the inverter 63 exceeds the threshold voltage Vthinv of the inverter 64. For this reason, only the output of the inverter 64 becomes Vout64 = L level (for example, 0 V).

  Next, immediately after the voltage Vin becomes larger than Vthinv × (R61 + R62) / R62, the output voltage Vout64 of the inverter 64 becomes equal to the voltage Vin. However, it takes time until the input voltage of the inverter 67 reaches the threshold voltage Vthinv due to the time constant of the resistor 65 and the capacitor 66 arranged at the output of the inverter 64, and the output voltage Vout67 of the inverter 67 at the time t14 is L level (for example, , 0V). The delay time from time t13 to time t14 is, for example, about 10 μsec.

  Therefore, as shown in FIG. 7, the reset circuit 6 has, for example, a reset signal R (voltage Vr) having an ON width of 10 μsec every time an ON signal (Vin = H level signal) is input to the IN terminal. Is output to the latch circuit 7.

  When the latch circuit 7 receives the reset signal R, the RS flip-flop circuit by the NOR circuits 73 and 74 is reset, and outputs an L-level self-blocking signal s1 (Vs1) to the output terminal. At this time, it is assumed that the input terminals 71a and 71b of the NOR circuit 71 receive L level signals representing normality from the timer circuit or the temperature detection circuit.

  Here, when the timer circuit or the temperature detection circuit detects an abnormality and receives an H level signal indicating the abnormality at the input terminals 71 a and 71 b of the NOR circuit 71, the signal is sent to the NOR circuit 73 via the NOR circuit 72. Is transmitted to. As a result, the RS flip-flop circuit by the NOR circuits 73 and 74 is set, and the latch circuit 7 outputs the H-level self-cutoff signal s1 (Vs1) to its output terminal.

  FIG. 8 is a diagram showing an ignition device for an internal combustion engine for an automobile, including a configuration example of an ignition IC according to the second embodiment. In FIG. 8, the same or equivalent components as those shown in FIG. 1 are denoted by the same reference numerals, and detailed description thereof is omitted.

  The ignition IC 2 according to the second embodiment is different from the ignition IC 2 according to the first embodiment in the detection circuit for the collector voltage Vc in the self-cutoff circuit 21. That is, in the self-cutoff circuit 21, a Zener diode 225 and a resistor 219 are connected in series between the C terminal and the E terminal. The connection point between the Zener diode 225 and the resistor 219 is connected to the non-inverting input terminal of the comparator 216 via the resistor 224, and the Zener diode 220 is connected between the non-inverting input terminal of the comparator 216 and the E terminal. .

  The reverse breakdown voltage of the Zener diode 225 can be set smaller than and near the collector voltage Vc to be detected via the reference voltage Vref. The Zener diode 220 protects the comparator 216 from a high voltage, and its reverse breakdown voltage is set sufficiently higher than the reference voltage Vref and sufficiently lower than the breakdown voltage of the comparator 216. The resistor 224 protects the Zener diode 220 from overcurrent.

  According to the ignition IC 2, when the collector voltage Vc rises and exceeds the reverse breakdown voltage of the Zener diode 225, a current flows through the resistor 219 and a voltage is generated at the resistor 219. This voltage is applied to the non-inverting input terminal of the comparator 216. Here, the resistor 219 also has a function of protecting the Zener diode 225 from overcurrent.

  The other operations of the ignition IC 2 are the same except for the ignition IC 2 and the collector voltage Vc detection method shown in FIG. Also in the second embodiment, the collector voltage Vc to be detected is the collector voltage threshold value Vcth as described in the first embodiment.

  The method of detecting the collector voltage Vc in the second embodiment is as follows. That is, when the collector voltage Vc exceeds the collector voltage threshold value Vcth, the Zener diode 225 becomes conductive and current starts to flow through the resistor 219. The current generates a voltage at the connection point between the Zener diode 225 and the resistor 219. The comparator 216 compares the generated voltage with the reference voltage Vref to detect that the collector voltage Vc exceeds the collector voltage threshold value Vcth.

  That is, for this purpose, for example, the reverse breakdown voltage of the Zener diode 225 can be set to the collector voltage Vc to be detected via the reference voltage Vref or the vicinity thereof, that is, the collector voltage threshold Vcth or the vicinity thereof.

  The detection operation of the comparator 216 when the reverse breakdown voltage of the Zener diode 225 is set to the collector voltage threshold value Vcth is as follows. That is, when the collector voltage Vc exceeds the collector voltage threshold value Vcth, the Zener diode 225 becomes conductive and current starts to flow through the resistor 219. Here, a voltage is generated across the resistor 219, and the voltage is applied to the non-inverting input terminal of the comparator 216. The reference voltage Vref can be set to a voltage generated at both ends of the resistor 219 or smaller than the voltage. For example, by doing so, the comparator 216 can detect when the collector voltage Vc exceeds the collector voltage threshold value Vcth. The value of the resistor 219 is desirably a high resistance so that even when a small current flows through the Zener diode 225, it can be detected. Note that the reference voltage Vref is desirably set sufficiently higher than the noise level so that the comparator 216 does not malfunction due to the noise voltage.

  FIG. 9 is a diagram showing an ignition device for an internal combustion engine for an automobile, including a configuration example of an ignition IC according to the third embodiment. In FIG. 9, the same or equivalent components as those shown in FIG. 1 are denoted by the same reference numerals, and detailed description thereof is omitted.

  In the ignition IC 2 according to the third embodiment, the detection part of the collector voltage Vc in the self-cutoff circuit 21 is changed as compared with the ignition IC 2 according to the first embodiment. That is, the resistor 218 in the self-cut-off circuit 21 of the first embodiment is replaced with a DepMOSFET (hereinafter referred to as a Deption Metal-Oxide Semiconductor Field-Effect Transistor) 226. The drain of the DepMOSFET 226 is connected to the collector of the IGBT 24. The gate of the DepMOSFET 226 is connected to the source of the DepMOSFET 226. The source of the DepMOSFET 226 is connected to one end of the resistor 219, and the other end of the resistor 219 is connected to the E terminal of the self-cutoff circuit 21 as in the case of the first embodiment.

  Next, the operation of the self-cutoff circuit 21 will be described. In this circuit, the DepMOSFET 226 operates as a resistor. Therefore, the collector voltage Vc is divided by the ON resistance of the DepMOS 226 and the resistor 219, and a positive voltage is applied to the non-inverting input terminal of the comparator 216. For this reason, assuming that the resistor 218 of the first embodiment is replaced with the DepMOSFET 226, the basic operation is the same as that of the first embodiment. The point that the Zener diode 220 is used as an overvoltage protection element of the comparator 216 is the same as in the case of the first embodiment. Here, the difference from the case of the first embodiment is that the DepMOS 226 also performs overcurrent protection of the Zener diode 220. That is, as the collector voltage increases, the DepMOS 226 becomes saturated and a saturated drain current value (for example, 100 μA) of the DepMOS 226 flows, and the Zener diode 220 is protected from overcurrent.

  FIG. 10 is a diagram showing an ignition device for an automobile internal combustion engine including a configuration example of an ignition IC according to a fourth embodiment. 10, the same or equivalent components as those shown in FIG. 1 are denoted by the same reference numerals and detailed description thereof is omitted.

  In the ignition IC 2 according to the fourth embodiment, the ignition IC 2 according to the first embodiment detects the timing of the start of slow shutoff based on the collector voltage Vc, whereas the gate voltage of the IGBT 24 Detection is based on Vg. That is, according to the self-cutoff circuit 21 of the ignition IC 2, the resistors 218 and 219 connected in series are arranged between the gate terminal and the E terminal of the IGBT 24, and the common connection point of the resistors 218 and 219 is connected to the comparator. 216 is connected to the inverting input terminal. In the self-cutoff circuit 21, the output of the reference voltage circuit 215 is connected to the non-inverting input terminal of the comparator 216. Further, the Zener diode 220 for overvoltage protection of the comparator 216, which is necessary in the self-cut-off circuit 21 of the ignition IC 2 according to the first embodiment, is removed.

  In this embodiment, as described above, the timing of the start of the gentle shut-off is detected based on the gate voltage Vg of the IGBT 24. That is, the description will be made using the gate voltage threshold Vgth described in the description of the first embodiment as follows.

  After the H-level self-shutoff signal s1 is output from the self-shutdown signal source 211, the gate voltage Vg is reduced to the gate voltage threshold voltage Vgth until the gate voltage Vg falls to the gate voltage threshold value Vgth. After being below the threshold value Vgth, a gentle shut-off is performed. For this purpose, the values of the resistor 218 and the resistor 219 that determine the voltage division of the gate voltage Vg and the reference voltage Vref are set so as to detect whether the gate voltage Vg is below or below the gate voltage threshold value Vgth.

  According to this self-cutoff circuit 21, the gate voltage Vg of the IGBT 24 is divided by the resistors 218 and 219 and applied to the inverting input terminal of the comparator 216. When the gate voltage Vg becomes small and the voltage at the inverting input terminal of the comparator 216 becomes smaller than the reference voltage of the reference voltage circuit 215, the output signal s2 of the comparator 216 becomes H level, so that it is possible to start a gentle shut-off. . In the example shown in FIG. 4, when the gate voltage Vg drops from 5V to 3.2V, the logic output of the comparator 216 is inverted, the transistor M3 is turned off, and the gentle shutoff is started. Other operations of the ignition IC 2 are the same as those of the ignition IC 2 shown in FIG. That is, in FIG. 1, it can be understood that the detection operation using the collector voltage is replaced with the detection operation using the gate voltage Vg.

FIG. 11 is a view showing a modification of the ignition device for an automobile internal combustion engine including a configuration example of the ignition IC according to the fourth embodiment.
In this modified example, the resistor 213 shown in FIG. 10 is eliminated, and the resistor 218 and the resistor 219 serve as a minute current circuit for flowing the minute current that the resistor 213 was responsible for. A combined resistance of the resistor 218 and the resistor 219 also serves as the resistor 213 in the fourth embodiment. With this configuration, the resistance can be reduced by one, and when this resistance is built into the chip of the ignition IC 2, the chip area can be reduced, resulting in a cost reduction.

  FIG. 12 is a diagram showing an ignition device for an internal combustion engine for an automobile, including a configuration example of an ignition IC according to a fifth embodiment. In FIG. 12, the same or equivalent components as those shown in FIG. 1 are denoted by the same reference numerals, and detailed description thereof is omitted.

  In the ignition IC 2 according to the fifth embodiment, the ignition IC 2 according to the first embodiment detects the timing of the start of slow shut-off based on the collector voltage Vc, while the collector IC I Detect based on.

  That is, in this ignition IC 2, the IGBT 24 has a configuration in which a main element through which a main current flows and a current sense element that detects a current of the main element are connected, and collector terminals and gate terminals are connected to each other. ing. The emitter terminal of the main element of the IGBT 24 is connected to the E terminal, the emitter terminal of the current sensing element is connected to one terminal of the resistor 219, and the other terminal of the resistor 219 is connected to the E terminal. The connection point between the emitter terminal of the current sense element and the resistor 219 is connected to the inverting input terminal of the comparator 216, and the non-inverting input terminal of the comparator 216 is connected to the output of the reference voltage circuit 215 that generates the reference voltage Vref. Yes.

  The detection of the timing of the start of slow shutoff in the ignition IC according to the present embodiment will be described as follows using the collector current threshold Vcth described in the description of the first embodiment.

  After the H-level self-shutoff signal s1 is output from the self-shutdown signal source 211, the collector current Ic is quickly shut off until the collector current Ic decreases and reaches the collector current threshold value Icth. After being below the threshold value Icth, a gentle shut-off is performed. Therefore, the value of the resistor 219 for detecting the emitter current Ise of the current sense element corresponding to the collector current Ic of the main element and the reference so as to detect whether the collector current Ic is less than or less than the collector current threshold Icth. The voltage Vref is set.

  That is, in the self-cutoff circuit 21, the current output from the emitter terminal of the current sense element of the IGBT 24 is converted into a voltage by the resistor 219 and applied to the inverting input terminal of the comparator 216. The voltage converted by the resistor 219 has a value proportional to the collector current Ic. For this reason, the self-blocking circuit 21 detects the timing of the gentle blocking start based on the collector current Ic of the IGBT 24.

  According to the self-cutoff circuit 21, when the collector current Ic becomes small and the voltage at the inverting input terminal of the comparator 216 becomes smaller than the reference voltage of the reference voltage circuit 215, the output signal s2 of the comparator 216 becomes H level and becomes slow. You will be able to start blocking. In the example shown in FIG. 4, when the collector current Ic decreases from the saturation current of 17A to 16A, the logic output of the comparator 216 is inverted, the transistor M3 is turned off, and the gentle cutoff is started. Other operations of the ignition IC 2 are the same as those of the ignition IC 2 shown in FIG.

  FIG. 13 is a diagram showing an ignition device for an automobile internal combustion engine including a configuration example of an ignition IC according to a sixth embodiment. In FIG. 13, the same or equivalent components as those shown in FIG. 1 are denoted by the same reference numerals, and detailed description thereof is omitted.

  Compared with the ignition IC 2 according to the first embodiment, the ignition IC 2 according to the sixth embodiment defines an element that discharges the charge charged in the gate capacitor from the resistor 213 when the circuit is slowly shut off. The current source 227 is changed. Therefore, the ignition IC 2 operates in the same manner as the ignition IC 2 according to the first embodiment, except that the charge charged in the gate capacitance is discharged by the constant current source 227 at the time of slow interruption.

  FIG. 14 is a diagram showing an ignition device for an automobile internal combustion engine including a configuration example of an ignition IC according to a seventh embodiment. In FIG. 14, the same or equivalent components as those shown in FIG. 1 are denoted by the same reference numerals, and detailed description thereof is omitted.

  In the ignition IC 2 according to the seventh embodiment, the power supply circuit 23 and the B terminal are removed from the ignition IC 2 according to the first embodiment, and a diode 228 is newly added. The diode 228 has an anode terminal connected to the gate terminal of the IGBT 24 and a cathode terminal connected to the IN terminal. The IN terminal is also connected to the source terminal of the transistor M1 of the drive circuit 22. Although not shown, positive polarity of circuit elements such as the self-cutoff signal source 211, the reference voltage circuit 215, the comparator 216, the NAND circuits 217 and 221, and the inverter 212 used in the self-cutoff circuit 21 and the drive circuit 22 is not shown. Are also connected to the IN terminal. That is, the ignition IC 2 is based on a signal whose power is applied to the IN terminal. In an ignition IC called a one-chip igniter, a signal applied to the IN terminal in this way may be used as a power source.

  According to this ignition IC 2, when an ON signal (Vin = H level signal) is input to the IN terminal, the voltage applied to the IN terminal serving as the power source of the ignition IC is applied to the cathode of the diode 228. In addition, a voltage lower than that voltage is applied to the anode of the diode 228. In this case, the diode 228 does not particularly function, and the ignition IC 2 performs the same operation as the circuit according to the first embodiment.

  On the other hand, when an OFF signal (Vin = L level signal) is input to the IN terminal, the power supply voltage of the circuit in the ignition IC 2 becomes zero. When the power supply voltage becomes zero, the diode 228 rapidly discharges the charge charged in the gate capacitance of the IGBT 24 to the IN terminal side. Accordingly, the ignition IC 2 operates in the same manner as the ignition IC 2 according to the first embodiment even if the power is taken from a signal applied to the IN terminal.

  The form in which the power supply circuit 23 and the B terminal are excluded from the ignition IC 2 described in the seventh embodiment and a diode 228 is newly added is not limited to the first embodiment but the second embodiment to the second embodiment. It can be applied to the sixth embodiment and has the same effect.

  FIG. 15 is a diagram showing an ignition device for an automobile internal combustion engine including a configuration example of an ignition IC according to an eighth embodiment. In FIG. 15, the same or equivalent components as those shown in FIG. 1 are denoted by the same reference numerals, and detailed description thereof is omitted.

  In the ignition IC 2 according to the eighth embodiment, a resistor 214 and a transistor M4 are newly added to the ignition IC 2 according to the first embodiment (the transistor M4 becomes conductive during normal operation, A first switch circuit that shuts off when an abnormality is detected). The resistor 214 has one terminal connected to the source terminal of the transistor M2, and the other terminal connected to the drain terminal of the transistor M3 (the resistor 214 and the transistor M3 constitute a second switch circuit). . The transistor M4 has a gate terminal connected to the output terminal of the inverter 212, a drain terminal of the transistor M4 connected to the source terminal of the transistor M2, and a source terminal of the transistor M4 connected to the emitter terminal of the ignition IC2.

  In the ignition IC 2 according to the eighth embodiment, when a normal ON signal is input to the IN terminal and then an OFF signal (Vin = L level signal) is input to the IN terminal, the gate of the IGBT 24 The electric charge charged in the capacitor is rapidly discharged through the transistors M2 and M4.

  Next, when the self-interruption signal source 211 continuously outputs the self-interruption signal s1, the charge charged in the gate capacitance of the IGBT 24 from the time t1 to the time t2 of the self-interruption start in FIG. And discharged through the resistor 214 and the transistor M3. This discharge time is adjusted by the resistance value of the resistor 214 so as to be longer than the quick shut-off time (eg, 10 μs) during normal operation and sufficiently shorter than the slow shut-off time (eg, 16 ms). From time t2 to time t3 in FIG. 4, as in the case of the first embodiment, the transistor M3 is turned off, and the charge charged in the gate capacitance of the IGBT 24 is gradually increased by the resistor 213. It is discharged and slowly shuts off.

  During normal operation, a shorter voltage can be applied to the spark plug 5 when the discharge time of the charge charged in the gate capacitance of the IGBT 24 is shorter. However, if the decrease rate of the gate voltage Vg of the IGBT 24 between the time t1 and the time t2 at the time of self-shutdown in FIG. 4 is too short with respect to the delay time of the circuit operation from the detection of the collector voltage Vc to the shutoff of the transistor M3. The IGBT 24 is completely shut off before shifting to the slow shut-off, and the spark plug 5 may misfire.

  In the ignition IC 2 according to the first embodiment, the applied voltage of the spark plug 5 at the time of normal shut-off and the erroneous ignition of the spark plug 5 at the time of self-shutoff are in a contradictory relationship. In the ignition IC 2 according to the eighth embodiment, the time from the self-shutdown start time t1 to the time t2 in FIG. 4 is longer than the rapid shut-off time (eg, 10 μs) during normal operation by the resistor 214. , 100 μs. As a result, while the applied voltage of the spark plug 5 at the time of normal shut-off is increased, the applied voltage of the spark plug 5 at the time of self-shut-off is not increased so as to prevent erroneous ignition of the spark plug 5.

  The gate capacitance of the IGBT 24 during the normal shutdown of the ignition IC 2 described in the eighth embodiment, from the time t1 to the time t2 of the self-shutdown start in FIG. 4, and from the time t2 to the time t3. The mode of switching the path for discharging the electric charge charged to is not limited to the first embodiment, but can be applied to the second embodiment and the third embodiment, and the same effect is produced.

  FIG. 16 is a diagram showing an ignition device for an automobile internal combustion engine including a configuration example of an ignition IC according to a ninth embodiment. In FIG. 16, the same or equivalent components as those shown in FIGS. 10 and 15 are denoted by the same reference numerals, and detailed description thereof is omitted.

  In the ignition IC 2 according to the ninth embodiment, the ignition IC 2 according to the eighth embodiment detects the start timing of the gentle shut-off based on the collector voltage Vc, whereas the gate voltage of the IGBT 24 Detection is based on Vg. That is, according to the self-cut-off circuit 21 of the ignition IC 2, the gate voltage Vg of the IGBT 24 is connected in series between the gate terminal and the E terminal of the IGBT 24, as in the fourth embodiment shown in FIG. These are detected by the resistors 218 and 219, and this is compared by the comparator 216 with the reference voltage Vref of the reference voltage circuit 215 corresponding to the gate voltage threshold value Vgth. Therefore, in this embodiment, the timing of the gentle interruption start is when the comparator 216 detects that the gate voltage Vg has dropped and the gate voltage Vg has fallen below the gate voltage threshold value Vgth.

  Even in this case, when the self-cutoff signal source 211 continuously outputs the self-cutoff signal s1, the charge charged in the gate capacitance of the IGBT 24 from the time t1 to the time t2 of the self-cutoff start in FIG. It is discharged through the transistor M2, the resistor 214, and the transistor M3. Then, the transistor M3 is turned off from the time t2 to the time t3 of the self-shutoff start in FIG.

  FIG. 17 is a diagram showing an ignition device for an automobile internal combustion engine including a configuration example of an ignition IC according to a tenth embodiment. In FIG. 17, the same or equivalent components as those shown in FIGS. 12 and 15 are denoted by the same reference numerals, and detailed description thereof is omitted.

  In the ignition IC 2 according to the tenth embodiment, the ignition IC 2 according to the eighth embodiment detects the timing of the gentle cutoff based on the collector voltage Vc, while the collector IC I Detect based on. That is, according to the self-cutoff circuit 21 of the ignition IC 2, as in the fifth embodiment shown in FIG. 12, the collector current is detected by converting it into a voltage using the current sense element and the resistor 219. The comparator 216 compares with the reference voltage Vref of the reference voltage circuit 215 corresponding to the collector current threshold value Icth. Therefore, in this embodiment, the timing of the gentle shutoff start is when the collector current Ic has decreased and the comparator 216 has detected that the collector current Ic has fallen below the collector current threshold Icth.

  Even in this case, when the self-cutoff signal source 211 continuously outputs the self-cutoff signal s1, the charge charged in the gate capacitance of the IGBT 24 from the time t1 to the time t2 of the self-cutoff start in FIG. It is discharged through the transistor M2, the resistor 214, and the transistor M3. Then, the transistor M3 is turned off from the time t2 to the time t3 of the self-shutoff start in FIG.

  FIG. 18 is a diagram showing an ignition device for an automobile internal combustion engine including a configuration example of an ignition IC according to the eleventh embodiment. In FIG. 18, the same or equivalent components as those shown in FIG. 1 are denoted by the same reference numerals, and detailed description thereof is omitted.

  In the ignition IC 2 according to the eleventh embodiment, the drive circuit 22 is changed as compared with the ignition IC 2 according to the first embodiment. That is, in the drive circuit 22, the transistor M1 is changed from the p-type MOSFET to the n-type MOSFET transistor M1a, and an inverter 222 is further added between the output terminal of the NAND circuit 221 and the gate terminal of the transistor M1a. Yes. The drain terminal of the transistor M1a is connected to the output terminal of the power supply circuit 23. The source terminal of the transistor M1a is connected to the gate terminal of the IGBT 24 and the drain terminal of the transistor M2. The inverter 222 inverts the logical value of the output of the NAND circuit 221 and outputs the result.

  In the ignition IC 2, when an ON signal is input to the IN terminal, the output of the NAND circuit 221 becomes L level, the output of the inverter 222 becomes H level, the transistor M1a is turned on, and the transistor M2 is turned off. Conversely, when an OFF signal is input to the IN terminal, the output of the NAND circuit 221 becomes H level, the output of the inverter 222 becomes L level, the transistor M1a is turned off, and the transistor M2 is turned on.

Other operations of the ignition IC 2 are the same as those of the ignition IC 2 shown in FIG.
In the form in which the transistor M1 is changed from the p-type MOSFET to the n-type MOSFET transistor M1a and the inverter 242 is added, the transistors M1a and M2 and all the other MOSFETs constituting the logic circuit are configured only by the n-type MOSFET. can do. Specifically, these n-type MOSFETs form a p-type semiconductor region on the surface layer of the n-type semiconductor layer in the same substrate as the IGBT 24 having the n-type semiconductor layer as a drift layer. An n-type source region and a p-type source region constituting an n-type MOSFET are formed on the surface layer of the p-type semiconductor region. A gate electrode is formed on the n-type semiconductor layer between the source region and the drain region via a gate insulating film.

  This embodiment can be applied not only to the first embodiment but also to the second to tenth embodiments, and provides the same effects.

1 ECU
2 IC for ignition
3 ignition coil 4 power supply 5 spark plug 6 reset circuit 7 latch circuit 21 self-cutoff circuit 22 drive circuit 23 power supply circuit 24 IGBT
31 Primary coil 32 Secondary coil 61, 62 Resistor 63, 64 Inverter 65 Resistor 66 Capacitor 67 Inverter 71, 72, 73, 74 NOR circuit 71a, 71b Input terminal 211 Self shut-off signal source 212 Inverter 213, 214 Resistor 215 Reference voltage circuit 216 Comparator 217 NAND circuit 218,219 Resistor 220 Zener diode 221 NAND circuit 222 Inverter 224 Resistor 225 Zener diode 226 DepMOS
227 Constant current source 228 Diode M1, M1a, M2, M3, M4 transistor

Claims (19)

A semiconductor device for switching control of a power semiconductor element,
A gate pull-up circuit connected to the gate terminal of the power semiconductor element and pulling up the gate terminal based on an input signal;
A gate pull-down circuit connected to the gate terminal of the power semiconductor element and pulling down the gate terminal based on an input signal;
An abnormality detection circuit for detecting an abnormality in the energization state of the power semiconductor element;
A micro current circuit connected to the gate terminal of the power semiconductor element and for extracting charges from the gate capacitance of the power semiconductor element;
A voltage detection circuit for detecting a collector voltage connected to a collector terminal of the power semiconductor element;
A switch circuit connected between the gate pull-down circuit and an emitter terminal of the power semiconductor element;
With
When the abnormality detection circuit detects an abnormality, the gate pull-up circuit is shut off, the gate pull-down circuit is turned on, the charge is extracted from the gate capacitance of the power semiconductor element through the switch circuit, and the charge is extracted. When the voltage detection circuit detects that the rise in collector voltage due to the voltage exceeds a set value, the switch circuit is shut off and the charge is extracted by the minute current circuit. A power semiconductor element;
A gate pull-up circuit connected to the gate terminal of the power semiconductor element and pulling up the gate terminal based on an input signal;
A gate pull-down circuit connected to the gate terminal of the power semiconductor element and pulling down the gate terminal based on an input signal;
An abnormality detection circuit for detecting an abnormality in the energization state of the power semiconductor element;
A micro current circuit connected to the gate terminal of the power semiconductor element and for extracting charges from the gate capacitance of the power semiconductor element;
A voltage detection circuit for detecting a collector voltage connected to a collector terminal of the power semiconductor element;
A switch circuit connected between the gate pull-down circuit and an emitter terminal of the power semiconductor element;
With
When the abnormality detection circuit detects an abnormality, the gate pull-up circuit is shut off, the gate pull-down circuit is turned on, the charge is extracted from the gate capacitance of the power semiconductor element through the switch circuit, and the charge is extracted. When the voltage detection circuit detects that the rise in collector voltage due to the voltage exceeds a set value, the switch circuit is shut off and the charge is extracted by the minute current circuit.   The voltage detection circuit includes a voltage dividing circuit in which resistors are connected in series, a reference voltage circuit that outputs a reference voltage of the set value, a comparator that compares an output of the voltage dividing circuit with the reference voltage, and the abnormality detection circuit 2. A logic circuit that shuts off the switch circuit when the comparator detects an abnormality and the comparator detects an output of the voltage dividing circuit higher than the reference voltage. 2. The semiconductor device according to 2.   The voltage detection circuit includes a series circuit in which a diode and a resistor are connected in series, a reference voltage circuit that outputs a reference voltage of the set value, and an output of the series circuit when a collector voltage exceeds the withstand voltage of the diode. A comparator that compares with a reference voltage; and a logic circuit that shuts off the switch circuit when the abnormality detection circuit detects an abnormality and the comparator detects an output of the series circuit higher than the reference voltage. The semiconductor device according to claim 1, wherein the semiconductor device is provided.   3. The semiconductor device according to claim 1, wherein the minute current circuit is a resistor connected between a gate terminal and an emitter terminal of the power semiconductor element.   3. The semiconductor device according to claim 1, wherein the minute current circuit is a constant current circuit connected between a gate terminal and an emitter terminal of the power semiconductor element.   The gate pull-up circuit has one end connected to a power supply circuit, the other end connected to a gate terminal of the power semiconductor element, a signal for turning on the power semiconductor element is input as the input signal, and the abnormality detection 3. The semiconductor device according to claim 1, wherein the switch is a switch for energizing the gate terminal of the power semiconductor element from the power supply circuit when no abnormality is detected in the circuit.   The gate pull-up circuit has one end connected to the input terminal of the input signal, the other end connected to the gate terminal of the power semiconductor element, and a signal for turning on the power semiconductor element as the input signal; A switch that energizes the gate terminal of the power semiconductor element by the ON signal when the abnormality detection circuit does not detect abnormality, and the power semiconductor element is turned off at one end and the other end of the switch. 3. A semiconductor device according to claim 1, wherein a diode is connected to energize the gate terminal of the power semiconductor element to the emitter terminal when a signal to be input is input.   One end of the gate pull-down circuit is connected to the gate terminal of the power semiconductor element, the other end is connected to the switch, and a signal for turning off the power semiconductor element is input as the input signal, or the abnormality detection circuit 3. The semiconductor device according to claim 1, wherein the transistor is a transistor that energizes the switch from the gate terminal of the power semiconductor element when an abnormality is detected. 4. A semiconductor device for switching control of a power semiconductor element,
A gate pull-up circuit connected to the gate terminal of the power semiconductor element and pulling up the gate terminal based on an input signal;
A gate pull-down circuit connected to the gate terminal of the power semiconductor element and pulling down the gate terminal based on an input signal;
An abnormality detection circuit for detecting an abnormality in the energization state of the power semiconductor element;
A micro current circuit connected to the gate terminal of the power semiconductor element and for extracting charges from the gate capacitance of the power semiconductor element;
A voltage detection circuit connected to a gate terminal of the power semiconductor element to detect a gate voltage;
A switch circuit connected between the gate pull-down circuit and an emitter terminal of the power semiconductor element;
With
When the abnormality detection circuit detects an abnormality, the gate pull-up circuit is shut off, the gate pull-down circuit is turned on, the charge is extracted from the gate capacitance of the power semiconductor element through the switch circuit, and the charge is extracted. When the voltage detection circuit detects that the gate voltage drop caused by the voltage falls below a set value, the switch circuit is shut off and the charge is extracted by the minute current circuit.   The semiconductor device according to claim 10, wherein the voltage detection circuit also serves as the minute current circuit. A power semiconductor element;
A gate pull-up circuit connected to the gate terminal of the power semiconductor element and pulling up the gate terminal based on an input signal;
A gate pull-down circuit connected to the gate terminal of the power semiconductor element and pulling down the gate terminal based on an input signal;
An abnormality detection circuit for detecting an abnormality in the energization state of the power semiconductor element;
A micro current circuit connected to the gate terminal of the power semiconductor element and for extracting charges from the gate capacitance of the power semiconductor element;
A voltage detection circuit connected to a gate terminal of the power semiconductor element to detect a gate voltage;
A switch circuit connected between the gate pull-down circuit and an emitter terminal of the power semiconductor element;
With
When the abnormality detection circuit detects an abnormality, the gate pull-up circuit is shut off, the gate pull-down circuit is turned on, the charge is extracted from the gate capacitance of the power semiconductor element through the switch circuit, and the charge is extracted. When the voltage detection circuit detects that the gate voltage drop caused by the voltage falls below a set value, the switch circuit is shut off and the charge is extracted by the minute current circuit.   The semiconductor device according to claim 12, wherein the voltage detection circuit also serves as the minute current circuit. A semiconductor device for switching control of a power semiconductor element,
A gate pull-up circuit connected to the gate terminal of the power semiconductor element and pulling up the gate terminal based on an input signal;
A gate pull-down circuit connected to the gate terminal of the power semiconductor element and pulling down the gate terminal based on an input signal;
An abnormality detection circuit for detecting an abnormality in the energization state of the power semiconductor element;
A micro current circuit connected to the gate terminal of the power semiconductor element and for extracting charges from the gate capacitance of the power semiconductor element;
A voltage detection circuit connected to a sense emitter terminal of the power semiconductor element to detect a value obtained by converting a collector current of the power semiconductor element into a voltage;
A switch circuit connected between the gate pull-down circuit and an emitter terminal of the power semiconductor element;
With
When the abnormality detection circuit detects an abnormality, the gate pull-up circuit is shut off, the gate pull-down circuit is turned on, the charge is extracted from the gate capacitance of the power semiconductor element through the switch circuit, and the charge is extracted. When the voltage detection circuit detects that the voltage drop corresponding to the collector current caused by the current falls below a set value, the switch circuit is cut off and the charge is extracted by the minute current circuit. A power semiconductor element;
A gate pull-up circuit connected to the gate terminal of the power semiconductor element and pulling up the gate terminal based on an input signal;
A gate pull-down circuit connected to the gate terminal of the power semiconductor element and pulling down the gate terminal based on an input signal;
An abnormality detection circuit for detecting an abnormality in the energization state of the power semiconductor element;
A micro current circuit connected to the gate terminal of the power semiconductor element and for extracting charges from the gate capacitance of the power semiconductor element;
A voltage detection circuit connected to a sense emitter terminal of the power semiconductor element to detect a value obtained by converting a collector current of the power semiconductor element into a voltage;
A switch circuit connected between the gate pull-down circuit and an emitter terminal of the power semiconductor element;
With
When the abnormality detection circuit detects an abnormality, the gate pull-up circuit is shut off, the gate pull-down circuit is turned on, the charge is extracted from the gate capacitance of the power semiconductor element through the switch circuit, and the charge is extracted. When the voltage detection circuit detects that the voltage drop corresponding to the collector current caused by the current falls below a set value, the switch circuit is cut off and the charge is extracted by the minute current circuit. A semiconductor device for switching control of a power semiconductor element,
A gate pull-up circuit connected to the gate terminal of the power semiconductor element and pulling up the gate terminal based on an input signal;
A gate pull-down circuit connected to the gate terminal of the power semiconductor element and pulling down the gate terminal based on an input signal;
An abnormality detection circuit for detecting an abnormality in the energization state of the power semiconductor element;
A micro current circuit connected to the gate terminal of the power semiconductor element and for extracting charges from the gate capacitance of the power semiconductor element;
A voltage detection circuit for detecting a collector voltage connected to a collector terminal of the power semiconductor element;
A first switch circuit connected between the gate pull-down circuit and the emitter terminal of the power semiconductor element and conducting in normal operation;
A second switch circuit connected between the gate pull-down circuit and an emitter terminal of the power semiconductor element and having a larger resistance than the first switch circuit;
With
When the abnormality detection circuit detects an abnormality, the power semiconductor is shut off, the gate pull-down circuit is turned on, the first switch circuit is turned off, and the power semiconductor is connected via the second switch circuit. When the voltage detection circuit detects that the collector voltage is extracted from the gate capacitance of the element and the rise of the collector voltage due to the extraction of the charge exceeds a set value, the second switch circuit is shut off and the charge generated by the minute current circuit is Semiconductor device. A semiconductor device for switching control of a power semiconductor element,
A gate pull-up circuit connected to the gate terminal of the power semiconductor element and pulling up the gate terminal based on an input signal;
A gate pull-down circuit connected to the gate terminal of the power semiconductor element and pulling down the gate terminal based on an input signal;
An abnormality detection circuit for detecting an abnormality in the energization state of the power semiconductor element;
A micro current circuit connected to the gate terminal of the power semiconductor element and for extracting charges from the gate capacitance of the power semiconductor element;
A voltage detection circuit connected to a gate terminal of the power semiconductor element to detect a gate voltage;
A first switch circuit connected between the gate pull-down circuit and the emitter terminal of the power semiconductor element and conducting in normal operation;
A second switch circuit connected between the gate pull-down circuit and an emitter terminal of the power semiconductor element and having a larger resistance than the first switch circuit;
With
When the abnormality detection circuit detects an abnormality, the power semiconductor is shut off, the gate pull-down circuit is turned on, the first switch circuit is turned off, and the power semiconductor is connected via the second switch circuit. When the voltage detection circuit detects that the gate voltage drop due to the extraction of the charge is less than a set value, the second switch circuit is shut off and the charge generated by the minute current circuit is extracted. Semiconductor device.   The semiconductor device according to claim 17, wherein the voltage detection circuit also serves as the minute current circuit. A semiconductor device for switching control of a power semiconductor element,
A gate pull-up circuit connected to the gate terminal of the power semiconductor element and pulling up the gate terminal based on an input signal;
A gate pull-down circuit connected to the gate terminal of the power semiconductor element and pulling down the gate terminal based on an input signal;
An abnormality detection circuit for detecting an abnormality in the energization state of the power semiconductor element;
A micro current circuit connected to the gate terminal of the power semiconductor element and for extracting charges from the gate capacitance of the power semiconductor element;
A voltage detection circuit connected to a sense emitter terminal of the power semiconductor element to detect a value obtained by converting a collector current of the power semiconductor element into a voltage;
A first switch circuit connected between the gate pull-down circuit and the emitter terminal of the power semiconductor element and conducting in normal operation;
A second switch circuit connected between the gate pull-down circuit and an emitter terminal of the power semiconductor element and having a larger resistance than the first switch circuit;
With
When the abnormality detection circuit detects an abnormality, the power semiconductor is shut off, the gate pull-down circuit is turned on, the first switch circuit is turned off, and the power semiconductor is connected via the second switch circuit. When the voltage detection circuit detects that the voltage drop corresponding to the collector current due to the extraction of the charge is less than a set value, the second switch circuit is cut off and the minute switch is turned off. A semiconductor device, wherein charge is extracted by a current circuit.

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