JP5206198B2 - Driving circuit for power conversion circuit - Google Patents

Description

  The present invention relates to a drive circuit for a power conversion circuit that drives on / off a voltage-controlled switching element included in the power conversion circuit.

As this type of driving circuit, for example, as seen in Patent Document 1 below, a Zener diode and a bipolar transistor for clamping a gate voltage to a predetermined voltage between an emitter and a gate of an insulated gate bipolar transistor (IGBT) Are connected, and the bipolar transistor is turned on when the collector current of the IGBT exceeds a specified value. According to this, when the collector current of the IGBT becomes a value that may cause a decrease in the reliability, the gate voltage can be lowered, and thus the collector current can be limited.
JP-A-5-218836

  Incidentally, the power conversion circuit generally has an inductance component such as a parasitic inductor. For this reason, when the collector current is suddenly reduced by turning on the bipolar transistor, the back electromotive force corresponding to the inductance component is increased, which may cause a large surge. For this reason, even though the gate voltage is reduced with the intention of maintaining the reliability of the switching element, the reliability of the switching element may be reduced by a surge.

  The present invention has been made to solve the above-described problems, and the object thereof is to perform a process for avoiding an excessive current flowing in a voltage-controlled switching element included in a power conversion circuit. An object of the present invention is to provide a drive circuit for a power conversion circuit that can suitably suppress a surge.

  Hereinafter, means for solving the above-described problems and the operation and effects thereof will be described.

In the configuration 1 , the current flowing between the input terminal and the output terminal of the voltage-controlled switching element included in the power conversion circuit is equal to or higher than a specified value, so that the switching element is kept on while the switching element is kept on. In a drive circuit of a power conversion circuit including a regulation unit that regulates a voltage applied to the control terminal to a reference voltage, the conduction control terminal and the regulation unit are connected via a resistor.

  In the above invention, since the resistor is connected between the conduction control terminal and the regulating means, when the charge for turning on the switching element is pulled out from the conduction control terminal by the regulating means, the charge extraction speed is limited. can do. For this reason, the change rate of the voltage of the conduction control terminal can be relaxed, and as a result, the decrease rate of the current flowing between the input terminal and the output terminal of the switching element can be prevented from becoming excessively large. For this reason, even if it is a case where the process which avoids that an excessive electric current flows into a switching element is performed, a surge can be suppressed suitably.

Configuration 2 is characterized in that, in Configuration 1 , the resistor is provided separately from a charging path for charging the conduction control terminal to turn on the switching element.

  In the said invention, it can avoid that the resistance value of the said resistor is restrict | limited by the request | requirement at the time of charging the electric charge for making a switching element into an ON state to a conduction control terminal.

A configuration 3 includes a resistor in a discharge path that discharges electric charges for turning on the switching element from the conduction control terminal in the configuration 1 or 2 , and is connected between the conduction control terminal and the regulating means. The resistor and the resistor provided in the discharge path are the same.

  In the said invention, in order to provide the function for preventing the fall speed of the voltage of a conduction control terminal from becoming large too much, it can avoid adding a resistor newly.

The configuration 4 is characterized in that, in the configuration 3 , the discharge path is a path used when the switching element is driven on and off.

In the configuration 5 , in the configuration 3 , the discharge path is a path for forcibly turning off the switching element when a predetermined current or more flows between the input terminal and the output terminal for a predetermined time. It is characterized by being.

Configuration 6 is any one of Configurations 1 to 5 , wherein the regulating means is a path connecting the Zener diode provided between the conduction control terminal and the output terminal, and the conduction control terminal and the output terminal. And means for opening and closing an electrical path including the Zener diode.

A configuration 7 is characterized in that, in any one of the configurations 3 to 6, the regulating means is formed in an integrated circuit integrated into one chip together with a means for closing the discharge path.

  In the above invention, the terminal for connecting each of the means for opening and closing the discharge path and the regulating means to the conduction control terminal of the switching element can be a single terminal of the integrated circuit. For this reason, the number of terminals of the integrated circuit can be reduced.

Configuration 8 is any one of Configurations 1 to 7 , wherein the power conversion circuit includes a series connection body of a high potential side switching element and a low potential side switching element, and the switching means is connected to the conduction control terminal. The element is at least one of the high potential side switching element and the low potential side switching element.

  In the above invention, since the high-potential side switching element and the low-potential side switching element are connected in series, the current flowing between the input terminal and the output terminal of the switching element may be limited in the event of an abnormal current flowing through them. desired. For this reason, the merit of providing the regulation means is particularly great.

Configuration 9 is a drive circuit of a power conversion circuit that drives on / off a voltage-controlled switching element included in the power conversion circuit, a resistor having one terminal connected to a conduction control terminal of the switching element, and the resistance A single-chip integrated circuit in which a single terminal is connected to the other terminal of the body, and the integrated circuit transmits charges for turning on the switching element via the resistor. A function to turn off the switching element by pulling out to one terminal side, and maintaining the switching element on when the current flowing between the input and output terminals of the switching element exceeds a specified value A function of extracting a part of the electric charge from the conduction control terminal to the single terminal side through the resistor so as to regulate a voltage applied to the conduction control terminal; It is characterized in.

  In the above invention, since the resistor is connected between the single terminal and the conduction control terminal, when the charge for turning on the switching element is drawn from the conduction control terminal, the charge extraction speed is limited. can do. For this reason, when the current flowing between the input terminal and the output terminal of the switching element is equal to or greater than a specified value, the rate of change in voltage can be reduced when part of the charge is extracted from the conduction control terminal. For this reason, it is possible to avoid an excessive increase in the rate of decrease in the current flowing between the input terminal and the output terminal of the switching element. For this reason, even if it is a case where the process which avoids that an excessive electric current flows into a switching element is performed, a surge can be suppressed suitably.

  Further, in the present embodiment, when the charge is extracted from the conduction control terminal to turn off the switching element, and when the charge is extracted from the conduction control terminal to regulate the voltage applied to the conduction control terminal. A single terminal of an integrated circuit is used. For this reason, the number of terminals of the integrated circuit can be reduced.

In the configuration 10 , the power conversion circuit according to the configuration 9 includes a series connection body of a high potential side switching element and a low potential side switching element, and the switching element in which the resistor is connected to the conduction control terminal It is at least one of a potential side switching element and the low potential side switching element.

  In the above invention, since the high-potential side switching element and the low-potential side switching element are connected in series, the current flowing between the input terminal and the output terminal of the switching element may be limited in the event of an abnormal current flowing through them. desired. For this reason, the merit of having the above-described function for regulating the voltage applied to the conduction control terminal is particularly great.

(First embodiment)
Hereinafter, a first embodiment in which a drive circuit of a power conversion circuit according to the present invention is applied to a hybrid vehicle will be described with reference to the drawings.

  FIG. 1 shows the overall configuration of a motor generator control system according to this embodiment. The motor generator 10 is connected to a high voltage battery 12 via an inverter IV and a boost converter CV. Here, boost converter CV connects capacitor C, a pair of power switching elements Scp, Scn connected in parallel to capacitor C, a connection point between the pair of power switching elements Scp, Scn, and the positive electrode of high-voltage battery 12. And a reactor L. The voltage of the high-voltage battery 12 (for example, “288V”) is boosted up to a predetermined voltage (for example, “666V”) by turning on / off the power switching elements Scp, Scn. On the other hand, the inverter IV includes a series connection body of power switching elements Sup and Sun, a series connection body of power switching elements Svp and Svn, and a series connection body of power switching elements Swp and Swn. Body connection points are connected to the U, V, and W phases of motor generator 10, respectively. In the present embodiment, an insulated gate bipolar transistor (IGBT) is used as these power switching elements Sup, Sun, Svp, Svn, Swp, and Swn. In addition, diodes Dup, Dun, Dvp, Dvn, Dwp, and Dwn are connected in antiparallel to these.

  The control device 16 is a control device that uses the low-voltage battery 14 as a power source. The controller 16 controls the motor generator 10 and operates the inverter IV and the converter CV to control the control amount as desired. Specifically, the operation signals gcp and gcn are output to the driver unit DU to operate the power switching elements Scp and Scn of the converter CV. Further, in order to operate the power switching elements Sup, Sun, Svp, Svn, Swp, Swn of the inverter IV, the operation signals gup, gun, gvp, gvn, gwp, gwn are output to the driver unit DU. Here, the high-potential side operation signals gcp, gup, gvp, gwp and the corresponding low-potential side operation signals gcn, gun, gvn, gwn are complementary signals. In other words, the power switching elements Scp, Sup, Svp, Swp on the high potential side and the corresponding power switching elements Scn, Sun, Svn, Swn on the low potential side are alternately turned on.

  FIG. 2 shows the configuration of the driver unit DU. Hereinafter, the power switching elements Sup, Sun, Svp, Svn, Swp, and Swn are collectively described as the power switching element S, and the operation signals gup, ung, gvp, gvn, gwp, gwn, gcp, and gcn are operated. The signal g is collectively described.

  As shown in the figure, the driver unit DU includes a custom IC 20 which is a one-chip semiconductor integrated circuit. The terminal T1 of the custom IC 20 is connected to the gate of the power switching element S via a charging resistor 30 and a balance resistor 32 for adjusting the charging speed of the gate. On the other hand, the custom IC 20 includes a power supply 26 that supplies electric charges for charging the conduction control terminal (gate) so as to turn on the power switching element S. The power source 26 is connected to the terminal T <b> 1 through the resistor 28 and the input terminal and output terminal of the switching element 24. Incidentally, the balance resistor 32 is a resistor for adjusting a resistance value for suppressing LC resonance.

  Further, the terminal T2 of the custom IC 20 is connected to the gate of the power switching element S via the discharge resistor 42 for adjusting the discharge rate of the gate and the balance resistor 32. On the other hand, the custom IC 20 includes a switching element 40 that opens and closes between the terminal T5 and the terminal T2 connected to the emitter of the power switching element S.

  Further, the custom IC 20 includes a drive circuit 22 that drives the power switching element S. The drive circuit 22 drives the power switching element S by turning on and off the switching elements 24 and 40 based on the operation signal g input to the driver unit DU via an insulating means such as a photocoupler (not shown). . That is, when the operation signal g becomes logic “H” to indicate that the power switching element S is to be turned on, the switching element 24 is turned on and the switching element 40 is turned off. The gate of the element S is charged with a positive charge. Further, when the operation signal g becomes logic “L” to instruct to turn off the power switching element S, the power switching is performed by turning off the switching element 24 and turning on the switching element 40. Positive charges are discharged from the gate of the element S.

  Between the gate and the emitter of the power switching element S, a gate capacitor 46 and a stabilizing resistor 48 are connected in parallel. The gate capacitor 46 is for adjusting the speed at which the power switching element S is switched from the off state to the on state in cooperation with the charging resistor 30. The stabilization resistor 48 is for reliably lowering the gate potential to the emitter potential under the condition where the power switching element S is turned off (when the operation signal g is set to logic “L”). For this reason, the resistance value of the stabilizing resistor 48 is set to a sufficiently large value as compared with the charging resistor 30 and the discharging resistor 42.

  The power switching element S includes a sense terminal ST that outputs a minute current having a correlation with a current (collector current) flowing between its input terminal (collector) and output terminal (emitter). The sense terminal ST is electrically connected to the emitter through a series connection body of resistors 50 and 52. As a result, a voltage drop occurs in the resistor 52 due to the current output from the sense terminal ST. Therefore, the amount of voltage drop due to the resistor 52 is correlated with the current flowing between the input terminal and the output terminal of the power switching element S. State quantity.

  The amount of voltage drop due to the resistor 52 is taken into the non-inverting input terminal of the comparator 54 via the terminal T4. On the other hand, a threshold voltage Vref is applied to the inverting input terminal of the comparator 54. Accordingly, when the collector current becomes equal to or larger than the threshold value, the comparator 54 is inverted from the logic “L” to the logic “H”. The logic “H” signal of the comparator 54 is taken into the delay 60 as the fail signal FL. The delay 60 outputs a logic “H” signal to the gate of the switching element 62 so that the power switching element S is forcibly turned off when the input signal becomes logic “H” for a predetermined time. At the same time, a stop signal AE is output to the drive circuit 22. Here, the stop signal AE is a signal for stopping the driving of the switching elements 24 and 40 by the drive circuit 22.

  On the other hand, the output terminal of the switching element 62 is connected to the terminal T5, and the input terminal is connected to the gate of the power switching element S via the terminal T3, the soft cutoff resistor 64, and the balance resistor 32. . As a result, the state where the collector current is equal to or greater than the threshold value continues for a predetermined time or longer, whereby the switching element 62 is turned on, and the charge of the gate of the power switching element S is discharged via the soft cutoff resistor 64. . Here, the resistance value of the soft blocking resistor 64 is higher than that of the discharging resistor 42. This is because, under a situation where the collector current is excessive, if the speed at which the power switching element S is switched from the on state to the off state, in other words, the cutoff speed between the collector and the emitter is increased, the surge becomes excessive. This is in view of the fear. For this reason, under the situation where the collector current is determined to be equal to or greater than the threshold value, the gate of the power switching element S is discharged through a path having a larger resistance value than the discharge path including the discharge resistor 42.

  The output signal of the comparator 54 is further applied to the gate of an N-channel MOS field effect transistor (switching element 56). The switching element 56 has one terminal connected to the emitter of the power switching element S and the other terminal connected to the anode side of the Zener diode 58. The cathode side of the Zener diode 58 is connected to the terminal T2. Thereby, when the output signal of the comparator 54 becomes logic “H”, the switching element 56 is turned on, and therefore the voltage of the gate of the power switching element S is limited to the breakdown voltage of the Zener diode 58. Become. This limits the collector current.

  Here, in the present embodiment, since the Zener diode 58 and the gate of the power switching element S are connected via the discharging resistor 42, the output signal of the comparator 54 is inverted to logic “H”. As shown in FIG. 3, it is possible to reduce the rate of decrease in the voltage of the gate of the power switching element S to the breakdown voltage. 3A shows the transition of the operation signal g of the power switching element S, FIG. 3B shows the transition of the gate voltage of the power switching element S, and FIG. 3C shows the failure signal FL. FIG. 3D shows the transition of the stop signal AE, and FIG. 3E shows the transition of the state of the switching element 24.

  As indicated by the solid line in the figure, when the fail signal rises, the gate voltage gradually decreases to the breakdown voltage. On the other hand, a one-dot chain line in the figure shows a case where no resistor is provided between the Zener diode 58 and the gate (specifically, the balance resistor 32). In this case, the gate voltage rapidly decreases as the fail signal FL rises. When the gate voltage is rapidly reduced, the collector current is rapidly reduced, so that a surge generated in the inverter IV and the converter CV is increased. On the other hand, as in this embodiment, by providing the discharge resistor 42 between the cathode of the Zener diode 58 and the gate of the power switching element S, the rate of decrease in the gate voltage at the time of rising of the fail signal FL can be reduced. Thus, the surge voltage can be suitably reduced.

  Incidentally, in the figure, the predetermined time T is the duration of the logic “H” of the input signal required to set the output of the delay 60 to the logic “H”. When the predetermined time T elapses, the switching element 62 is turned on, so that the gate charge of the power switching element S is forcibly discharged. At this time, since the stop signal AE is inverted to the logic “L”, the switching element 24 is turned off, and no new charge is supplied to the gate of the power switching element S. For this reason, the power switching element S is forcibly turned off.

  According to the embodiment described in detail above, the following effects can be obtained.

  (1) The gate of the power switching element S and the cathode of the Zener diode 58 are connected via a resistor. Thereby, even if it is a case where the process which avoids that an excessive electric current flows into the power switching element S is performed, a surge can be suppressed suitably.

  (2) The resistor for connecting the gate of the power switching element S and the cathode of the Zener diode 58 is the discharge resistor 42. Thereby, in order to provide the function for preventing the voltage decrease rate of the power switching element S from becoming excessively large, it is possible to avoid newly adding a resistor.

  (3) A charge path resistor (charging resistor 30) for charging a charge for turning on the power switching element S, and a discharge path resistor (discharge resistor 42) for discharging the charge. ) And separate members. Thereby, the freedom degree for adjusting the charge rate and discharge rate of a gate can be raised.

  (4) A resistor (charging resistor 30) in a charging path for charging a charge for turning on the power switching element S is connected to the gate of the power switching element S and the cathode of the Zener diode 58. Therefore, the resistor is a separate member. Thereby, the freedom degree for adjusting the charge rate of a gate can be raised.

  (5) The Zener diode 58 and the switching elements 40 and 56 are formed in the custom IC 20. Thereby, the resistor for connecting between the gate of the power switching element S and the cathode of the Zener diode 58 is the discharging resistor 42, so that the number of terminals of the custom IC 20 can be reduced.

  (6) The discharging resistor 42 is configured by discrete components separately from the custom IC 20. Thereby, even after the specification of the custom IC 20 is determined, or even after the custom IC 20 is manufactured, the discharge rate of the gate can be suitably adjusted.

  (7) The power switching element S to be overcurrent protected is a high potential side switching element and a low potential side switching element constituting the inverter IV and the converter CV. Thus, it is desirable to limit the current flowing between the input terminal and the output terminal of the switching element in the event of an abnormal current flowing between the high potential side switching element and the low potential side switching element. For this reason, the merit of providing the Zener diode 58 and the like is particularly great.

(Second Embodiment)
Hereinafter, the second embodiment will be described with reference to the drawings with a focus on differences from the first embodiment.

  FIG. 4 shows the configuration of the driver unit DU according to the present embodiment.

  As shown in the figure, in this embodiment, the resistor for connecting the gate of the power switching element S and the cathode of the Zener diode 58 is a soft cutoff resistor 64. Also according to this, it is possible to obtain the effects according to the effects (1) to (7) of the first embodiment.

(Other embodiments)
Each of the above embodiments may be modified as follows.

  In the first embodiment, the resistor for reducing the rate of decrease in the gate voltage when the gate voltage is regulated by the Zener diode 58 is shared with the discharge resistor 42. A separate resistor may be used.

  In the above-described embodiment, the Zener diode 58, the switching element 56, the comparator 54, and the like are configured as circuits inside the custom IC 20. However, the present invention is not limited thereto, and these may be configured by discrete components outside the custom IC 20. .

  In each of the above embodiments, the charging resistor 30 and the discharging resistor 42 are separate members. However, the present invention is not limited to this, and the gate resistors may be the same as each other (may be shared).

  In each of the above embodiments, the charging resistor 30 and the discharging resistor 42 are configured by discrete components, but not limited thereto, may be configured in the custom IC 20.

  As a regulating means for regulating the voltage applied to the conduction control terminal of the power switching element to the reference voltage while maintaining the power switching element in the on state, the regulating means is configured to include the Zener diode 58 and the switching element 56. Not exclusively. For example, instead of the Zener diode 58, a series connection body of a plurality of diodes having the gate side of the power switching element S as an anode may be used.

  The means for detecting the electrical state quantity correlated with the current flowing between the input terminal and the output terminal of the power switching element is not limited to the means for detecting the current output from the sense terminal ST. For example, a means for detecting a voltage between the input terminal and the output terminal may be used.

  In the above embodiment, the power switching element of each arm of each phase is configured as a single power switching element as the inverter IV, but is not limited thereto, and may be configured with a plurality of power switching elements. In this case, when a resistor for connecting the gate of the power switching element S and the Zener diode 58 is provided separately from the discharging resistor 42 and the soft cutoff resistor 64, the number of components as an entire power conversion system is increased. Becomes more serious. For this reason, as exemplified in the above embodiments, it is particularly effective to share the resistor connecting the gate of the power switching element S and the Zener diode 58 with the discharging resistor 42 and the soft cutoff resistor 64. It is.

  The configuration of the driver unit DU is not limited to that exemplified in the above embodiment and its modifications, and for example, a configuration without the gate capacitor 46, the balance resistor 32, and the stabilizing resistor 48 may be employed.

  The power switching element of the power conversion circuit is not limited to the inverter IV and the converter CV connected between the vehicle-mounted rotating machine and the battery. For example, it may be a power switching element that constitutes a DCDC converter that steps down the voltage of the high-voltage battery in order to supply the power of the on-vehicle high-voltage battery to the low-voltage battery.

  The power switching element of the power conversion circuit is not limited to the IGBT but may be, for example, a MOS field effect transistor.

1 is a system configuration diagram according to a first embodiment. FIG. The circuit diagram which shows the circuit structure of the driver unit concerning the embodiment. The time chart which shows the effect of the embodiment. The circuit diagram which shows the circuit structure of the driver unit concerning 2nd Embodiment.

Explanation of symbols

  42 ... Discharge resistor, 56 ... Switching element, 58 ... Zener diode, S ... Power switching element, IV ... Inverter, CV ... Converter.

Claims (9)

When the current flowing between the input terminal and the output terminal of the voltage control type switching element provided in the power conversion circuit becomes a specified value or more, it is applied to the conduction control terminal of the switching element while maintaining the switching element in the ON state. In the drive circuit of the power conversion circuit comprising a regulation means for regulating the voltage to be a reference voltage,
A resistor is provided in a first discharge path for discharging electric charge for turning on the switching element from the conduction control terminal,
The conduction control terminal and the regulating means are connected via a resistor,
The regulating means is provided in a second discharge path that is an electric path different from the first discharge path,
A drive circuit for a power conversion circuit, wherein the resistor connected between the conduction control terminal and the regulating means is the same as the resistor provided in the first discharge path .   2. The driving of the power conversion circuit according to claim 1, wherein the resistor is provided separately from a charging path for charging the conduction control terminal to turn on the switching element. circuit. 3. The power conversion circuit drive circuit according to claim 1, wherein the first discharge path is a path used when the switching element is turned on / off. 4. The first discharge path is a path for forcibly turning off the switching element when a predetermined current or more flows between the input terminal and the output terminal for a predetermined time. The drive circuit of the power converter circuit according to claim 1 or 2 . The second discharge path is a path connecting the conduction control terminal and the output terminal,
The regulating means, the Zener diode provided in the second discharge path, the power according to any one of claims 1-4, characterized in that it comprises a means for opening and closing the discharge path of the second Drive circuit for conversion circuit. The regulating means, the power converter circuit according to any one of claims 1 to 5, characterized in that the first discharge path formed within an integrated circuit that is made into one chip together with means for the closed state Drive circuit. The power conversion circuit includes a series connection body of a high potential side switching element and a low potential side switching element,
Switching elements said regulating means is connected to the conduction control terminal, in any one of claims 1 to 6, characterized in that at least one of the high potential-side switching element and the low potential side switching elements A drive circuit of the power conversion circuit described. In the drive circuit of the power conversion circuit that drives the on / off of the voltage control type switching element included in the power conversion circuit,
A resistor having one terminal connected to the conduction control terminal of the switching element;
A single-chip integrated circuit having a single terminal connected to the other terminal of the resistor,
The integrated circuit includes a first discharge path provided in the integrated circuit and connected to the single terminal; and the first discharge path provided in the integrated circuit and connected to the single terminal. A second discharge path that is an electrical path different from the discharge path,
The integrated circuit further turns off the switching element by drawing out charges for turning on the switching element to the first discharge path side through the resistor and the single terminal. And the conduction control to regulate the voltage applied to the conduction control terminal while maintaining the switching element on when the current flowing between the input and output terminals of the switching element exceeds a specified value. A drive circuit for a power conversion circuit comprising a function of extracting a part of the electric charge from a terminal to the second discharge path side through the resistor and the single terminal . The power conversion circuit includes a series connection body of a high potential side switching element and a low potential side switching element,
9. The drive circuit for a power conversion circuit according to claim 8 , wherein the switching element to which the resistor is connected to the conduction control terminal is at least one of the high potential side switching element and the low potential side switching element. .

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