JP5427633B2 - Gate drive device - Google Patents

Description

  The present invention relates to a gate control system of a power converter system such as an inverter and a converter, and particularly relates to high reliability of the circuit system.

  The power converter includes an inverter circuit, a step-up and step-down circuit, and an electric circuit including a switch and a diode.

  Power converters such as inverters and converters are used to perform DC and AC power conversion and AC frequency conversion. From a switching power supply for step-up / step-down, large-capacity motor drive systems and power transmission It is used in various applications such as power systems such as substations.

  As a converter element used in the above system, a high-voltage power semiconductor element such as a transistor or a diode is used in a large-capacity application from the viewpoint of reducing loss.

  In order to improve the efficiency of converters, power semiconductors are required to have low loss. At the same time, in inverters using power semiconductors, high reliability is achieved by reducing switching loss as well as EMI (electro-magnetic interference) noise. Is required. Based on the current command value based on the collector current and the method of switching the gate resistance by sequentially detecting the current change rate of the transistor at the time of turn-on as a method to achieve both the loss generated when the power transistor is turned on and the reduction of EMI noise, There is a method for switching the switching speed.

JP 2005-278274 A JP 2009-27881 A

  Use when the power semiconductor is operating at a low temperature, such as when the power converter is turned on again from hibernation, or when the temperature of the power semiconductor is increased, such as when the load on the power converter increases. When the temperature is out of the normal operating temperature range, noise at turn-on may occur.

  Although noise may occur due to the operation of the power transistor itself, depending on the operating conditions of the diode, switching loss and EMI noise may increase due to current oscillation and voltage oscillation of the diode. In particular, in the case of a high-voltage diode, the output voltage or output current may vibrate greatly and become a noise source depending on the temperature characteristics during the recovery operation at the time of diode reverse bias and the current value at the time of current flow. Also, when PWM pulse control is used in an inverter circuit, the diode conduction time becomes extremely short, and an oscillation phenomenon may occur under conditions where the conduction current is small.

  As a method for solving the above-mentioned problem of the high voltage diode, the pulse width at the time of generating the control pulse is compared with a predetermined pulse width threshold value, and the device temperature estimation information is compared with the predetermined temperature threshold value. The gate resistance is switched according to the operating conditions that increase.

  Alternatively, the driving condition of the switching element for the arm is made gentler when operating at a temperature at which the oscillation phenomenon of the diode used in the power semiconductor occurs or when generating a control pulse with a short conduction time.

  According to the present invention, the diode can be driven to reduce the current change rate and the voltage change rate, and EMI noise caused by the diode can be reduced. Further, when the EMI noise of the diode is not satisfied, the loss can be reduced by driving the switching element at a high speed by reducing the gate impedance which is a driving condition of the switching element. As described above, the present invention can achieve both the effects of reducing the EMI noise and the loss of the power semiconductor. Further, it is possible to simplify the logic at the time of pulse generation in the logic unit.

FIG. 3 is an explanatory diagram of the first embodiment. Explanatory drawing of Example 2. FIG. Explanatory drawing of Example 3. FIG. Explanatory drawing of Example 4. FIG. Explanatory drawing of Example 5. FIG. Explanatory drawing of Example 6. FIG. Explanatory drawing of Example 7. FIG. Explanatory drawing of Example 8. FIG. Explanatory drawing of Example 9. FIG. Explanatory drawing of Example 10. FIG. Explanatory drawing of Example 11. FIG. Explanatory drawing of Example 12. FIG. Explanatory drawing of Example 13. FIG. Explanatory drawing of Example 14. FIG.

  Embodiments of the present invention will be described below with reference to the drawings.

  The configuration of the converter circuit according to the first embodiment of the present invention will be described with reference to FIG. FIG. 1 shows a basic circuit having a power semiconductor composed of a switching element 1 and a diode 2 in a converter circuit, and a gate drive unit including a gate drive circuit and a pulse generator 5 as a converter circuit configuration of the present invention. In FIG. 1, 1 is a switching element, 2 is a diode, 3 is a variable gate resistor, 4 is a gate drive circuit, 5 is a pulse generator, 6 is a power semiconductor temperature estimating means, 7 is a gain change signal generator, and 8 is a first Reference numeral 1 denotes an AND circuit, 9 denotes a first pulse width detection circuit, and 101 denotes a diode.

  The circuit of this embodiment will be described with reference to FIG.

  A converter circuit in which semiconductor switching elements are combined is composed of a power semiconductor including a switching element 1 for controlling electric power and a diode 2. Further, the converter circuit includes a gate drive circuit 4 that drives the gate of the switching element 1 in order to control the on / off of the switching element 1, and the converter circuit uses the output from a control logic unit including a microcomputer and a CPU. A pulse generator 5 for generating a pulse for controlling a necessary current and voltage is provided. In recent years, an insulated gate bipolar transistor (hereinafter abbreviated as IGBT) is used for many switching elements for converters. In this embodiment, a circuit diagram of a converter using an IGBT as the switching element 1 in FIG. explain. Further, as a basic configuration of a power converter using an IGBT, a gate drive circuit indicated by 4 is used to amplify a signal from a control logic unit.

  A power source or other power semiconductor, a passive element, or a load is attached to the collector terminal and the emitter terminal of the IGBT, and the ON / OFF operation of the switching element 1 is determined by a signal output from the pulse generator 5. The gate voltage of the switching element 1 is controlled to change the collector-emitter voltage and the collector current.

  In the case of a DC-to-AC converter (inverter) circuit, a combination diode 101 is connected in series to the collector or emitter terminal of the IGBT. Therefore, the combination diode 101 has a reverse recovery operation (recovery operation), and is connected to the IGBT. The flowing collector current has a waveform having a peak instantaneously. The temperature characteristic of the combination diode 101 becomes a problem. Therefore, in this embodiment, the estimated temperature information of the power semiconductor output from the power semiconductor temperature estimation means 6 such as a thermistor or a thermocouple is compared with a predetermined temperature threshold by the gain change signal generator 7 and output. , Input to the first AND circuit 8. Here, the power semiconductor temperature estimation means 6 can estimate the temperature of at least one of the switching element 1 and the diode 2. Further, the current estimation value calculated from the pulse width detected by the first pulse width detection circuit 9 is output to the first AND circuit 8 and compared with a predetermined pulse width threshold value, and the first AND circuit 8 is compared. To enter. By comparing the signals from 7 and 9, a condition in which the influence of the noise of the combination diode becomes large is detected. Based on the output of the first AND circuit 8, the resistance of the variable gate resistor 3 is switched to a large value.

  By switching the gate drive impedance in such a manner that the EMI of the diode occurs, the effects of the present invention can be realized without feedback of the current and the current change rate.

  The configuration of the converter circuit according to the second embodiment of the present invention will be described with reference to the drawings. FIG. 2 shows an example of a gate driving method in which a signal for changing the gate impedance is transmitted in accordance with the change in the gate voltage and is switched transiently at the turn-on time. The gain change signal generation unit 7 has a determination condition for a pulse in which EMI of the diode is generated in advance. The gain change signal generation unit 7 receives the pulse signal from the pulse generation unit 5 and compares it with the temperature information received from the power semiconductor temperature estimation unit 6. Then, a gain change signal for changing the gate impedance is generated. By changing the output of the gain change signal generator 7 and the gate voltage to a large value using the first comparator 10, the IGBT which is the switching element 1 is turned on. When the voltage oscillation of the collector or emitter or current oscillation is generated by the diode 2 at the moment when the diode is detected, a change in the collector current of the IGBT which is the switching element 1 is detected, and the noise of the diode is observed while checking the timing of the IGBT switch. It is possible to provide a circuit system capable of changing the current change rate and the voltage change rate of the IGBT in accordance with the moment of occurrence.

  A converter circuit system according to the third embodiment of the present invention will be described with reference to FIG. FIG. 3 shows a configuration in which a delay circuit 11 is added between the gate drive circuit 4 of the gate drive system shown in the second embodiment and the pulse generator 5. The configuration other than the delay circuit 11 is the same as that of the second embodiment.

  In this embodiment, by synchronizing the on / off signal from the pulse generator 5 to the gate drive circuit 4 and the processing of the gain change pulse, a suitable gate drive system can be provided.

  The configuration of the converter circuit according to the fourth embodiment of the present invention will be described with reference to FIG. FIG. 4 shows the converter circuit configuration of the present invention, in which the IGBT as the switching element 1 and a power semiconductor of a diode are connected in series, and a gain change signal generator is provided in each gate drive circuit that drives the positive-side IGBT and the negative-side IGBT. And a power semiconductor composed of a switching element and a diode in a converter circuit, and two basic circuits composed of a gate drive unit composed of a gate drive power source and a pulse generation unit. The same components as those in FIG. 1 are denoted by the same reference numerals.

  In FIG. 4, 12 is a positive terminal, 13 is a negative terminal, 14 is a second switching element, 15 is a second diode, 16 is a second variable resistor, 17 is a second gate drive circuit, and 18 is an output terminal. , 19 represents a second gain change signal generator, and 20 represents a second AND circuit.

  In a DC-to-AC converter (inverter) circuit in which the positive electrode terminal 12 and the negative electrode terminal 13 are connected to a DC power source and the output terminal indicated by 18 is connected to a load, the switching elements indicated by 1 and 14 are respectively driven. In this case, according to the change in the collector-emitter voltage of the switching element indicated by 1, a voltage is applied to the opposite diode indicated by 15 second diode. For example, in the above-described inverter circuit, when a voltage source is attached to the terminals 12 and 13 and a switching element such as an IGBT is turned on, a fall of the collector-emitter voltage of the switching element indicated by 1 Accordingly, the cathode-anode voltage of 15 which is the opposite diode rises. At this time, if the device temperature of the operating diode 15 and the current passing time of the current to be passed are short, current oscillation and voltage oscillation at the time of diode recovery may occur and cause EMI noise. In this way, when switching the IGBT under conditions where current oscillation and voltage oscillation of the diode occur, the gate impedance of the switching element on the opposite side is greatly changed at the moment when noise is generated at the time of oscillating diode recovery. It is possible to suppress EMI noise during diode recovery.

  In the present embodiment, the method described in the first embodiment can be applied to the gate control at the moment when the IGBT 1 on the positive electrode terminal side in FIG. 4 is turned on. Specifically, in order to perform EMI suppression of the diode 15 on the negative electrode terminal side, in this embodiment, when the pulse generator 5 generates a pulse signal under the condition that the diode 15 generates EMI, the pulse width The detection circuit 9 detects that the pulse signal received from the pulse generator matches the condition for generating EMI. The gain change signal generation unit 7 compares the estimated temperature value of the diode 15 detected by the power semiconductor temperature estimation unit with a predetermined temperature threshold value, and outputs the output signal generated by the gain change signal generation unit 7 as a first value. To the AND circuit 8. In the first AND circuit, the signal from the gain change signal generation unit 7 and the pulse width detection circuit 9 is compared to detect a condition that the influence of the noise of the combination diode increases, and the variable gate resistance indicated by 3 is set. Change.

  The configuration of the converter circuit according to the fifth embodiment of the present invention will be described with reference to FIG. As shown in the second embodiment, the gate drive speed of the IGBT 1 is changed using the output signal of the first comparator 10 that compares the gate voltage with the output signal of the gain change signal generator 7. An embodiment will be described in which a gate driving method is applied to the inverter circuit for determining and increasing the constant of the variable gate resistance 3 to loosen the gate driving condition for a predetermined time.

  Reference numeral 10 denotes a first comparator. The object can be achieved by changing the variable gate resistor 3 using the first comparator 10 that compares the gate voltage of the switching element 1 on the positive electrode side and the output signal of the gain change signal generator 7. it can.

  In the fourth and fifth embodiments, the gate driving method for suppressing the EMI of the negative-side diode 15 has been described. However, the EMI suppression of the positive-side diode 2 is also controlled by the negative-side switching element 14 as in the fourth and fifth embodiments. The EMI suppression of the positive-side diode 2 can be realized by the gate driving method.

  That is, a power semiconductor temperature estimation means 6 for detecting the temperature of the diode 2 is included in the control of the IGBT 14 on the negative electrode side at the time of turn-on, and a pulse having a time width under which the diode 2 vibrates is generated by the pulse generator 5. In this case, the above problem can be achieved by changing the gate drive impedance of the second switching element 14, which is the IGBT on the negative electrode side, by the variable gate resistor 16 as compared with the estimated temperature value of the diode 2. .

  The collector-emitter voltage Vce and the collector current Ic when the gate drive system shown in the second embodiment is used when the IGBT of the inverter circuit is turned on are shown. In addition, FIG. 6 shows an example of the gain change pulse at that time and a schematic diagram of the temporal change of the gate resistance and EMI noise. A broken line is a schematic diagram of a conventional collector-emitter voltage, a gate resistance, and an EMI noise waveform at that time.

  FIG. 6 shows the best change in the variable gate resistance when a signal for changing the resistance value of the variable gate resistor 3 is transmitted from the gain change signal generation unit 7 of the second embodiment without time delay.

  A transient phenomenon at the time of IGBT turn-on and generation of EMI noise will be described with reference to FIG. Charges are sufficiently supplied to the gate capacitance of the IGBT by the gate driving device, and the voltage becomes higher than the gate threshold value of the IGBT. At time tA, collector current Ic starts to flow, and collector-emitter voltage Vce starts to fall. From time tC onward, the current Ic flows as determined by the return current of the diode or the on / off pulse control of the logic section. Between times tA and tC, a reverse recovery of the combination diode causes a diode recovery current larger than the current Ic determined by the control to be superimposed on the IGBT. The time when the diode recovery current is superimposed on the IGBT and becomes the current peak value Ip is defined as time tB. In the period from time tB to tC, the rate of time change of the voltage Vce is larger in the conventional method than in the case where the gate impedance is not changed as in the present invention. For this reason, the voltage change rate and current change rate of the opposite diode cannot be suppressed. For this reason, EMI noise increases at least until time tC ′ when the collector voltage is the same as that of the conventional method. Depending on the impedance of the load, the vibration may propagate without being attenuated after time tC ′.

  On the other hand, when the converter circuit operates under the condition that the voltage change of the diode such as the estimated temperature value of the power semiconductor or the time width of the control pulse becomes large as in the present invention, the gate impedance operation means is activated. EMI noise caused by diodes can be suppressed by providing a gate drive method that allows the gate drive conditions to be relaxed for a predetermined time at the instant when the recovery current reaches the peak Ip at time tB at the time of turn-on. can do.

  In addition to the EMI suppression method using the gate impedance changing means shown in each of the above embodiments, an example of a gain change pulse when the IGBT loss is reduced, and the gate resistance and EMI noise time at that time A schematic diagram of the change is shown. A broken line shows a conventional collector-emitter voltage, a gate resistance, and a schematic diagram of an EMI noise waveform at that time. The difference from the sixth embodiment is that the gate resistance is increased for a predetermined time to drive the IGBT gently, and from the time tC ′ when the collector-emitter voltage changes with the conventional method to the time tD when the IGBT falls to the conduction voltage. By making the gate resistance smaller than the initial gate resistance value before tB, an operation is performed to advance the time when the falling of the IGBT is completed to a time tD ′ earlier than the time tD.

  When such a control method is used for an inverter circuit, it is possible to achieve both suppression of EMI noise at the time of recovery of the diode on the controlled side and reduction of loss of the switching element to be controlled. In particular, in the case of an IGBT, a delay in voltage fall such as a period tC ′ to tD may occur due to a delay in bipolar operation. For this reason, the turn-on loss of the IGBT can be reduced by changing the time at which the initial gate resistance is tD to a gate control constant that is advanced to time tD ′.

  An example of a suitable circuit method for realizing the waveform shown in the seventh embodiment will be described with reference to FIG. The same components as those in FIG. 1 are denoted by the same reference numerals. In FIG. 8, reference numeral 24 denotes a counter diode voltage comparison means, and 23 denotes a third AND circuit. In the case of controlling the gate when the switching element is turned on, the positive side indicated by 1 in FIG. 1 sets a threshold value in advance for the voltage at the time of recovery of the opposite side diode using the opposite side diode voltage comparison means indicated by 24. .

  When the diode voltage at the time of recovery becomes equal to or higher than the threshold value, the output signal of the voltage comparison means indicated by 24 is transmitted to the third AND circuit 23, and this is compared with the signal of the gain change signal generator 7 to recover the recovery voltage. A gate drive process is performed to drive at a timing during the rise of the. The timing during which the recovery voltage is rising is when the IGBT voltage in the case of the inverter circuit starts to fall rapidly, that is, after time tB shown in FIG. This embodiment can be realized by mounting a circuit in which the gate resistance is lower than the impedance before tB.

  In this embodiment, the positive-side IGBT is used as a control constant, and the voltage output of the negative-side diode is used as a determination value for changing the gate impedance after time tB. The same applies to the negative-side IGBT. It is clear that the same effect as in the above-described embodiment can be obtained even when the voltage at the time of recovery of the positive-side diode is used as the threshold value as the determination value for changing the gate impedance of the negative-side IGBT when controlling.

  An example of a suitable circuit system for realizing the power semiconductor temperature estimation means will be described with reference to FIG. In this embodiment, in order to improve the EMI characteristics of the diode, as a means for estimating the temperature of the diode, the diode voltage detection means 24 for the diode on the opposite side whose current-voltage characteristics are shown in FIG. 8 and the output current are measured. An example using current measuring means will be shown. The same components as those in FIG. 8 are denoted by the same reference numerals. In FIG. 9, reference numeral 26 denotes a counter diode temperature estimation calculation unit, and 25 denotes output current measuring means. In the eighth embodiment, not only the voltage at the reverse bias is detected using the diode voltage detection means 24 of the opposite diode, but also the voltage drop at the time of the diode flow and the current measurement means indicated by 25 are used to move forward. In this example, the current is measured and processed by the diode temperature estimated value calculation unit indicated by 26 from the voltage-current characteristics of the diode, and the gain change signal generation unit 7 outputs the gain change signal. For example, in the case of a converter circuit that moves an AC motor by vector control, the current measuring means indicated by 25 is generally provided with a current probe on the AC output side. By combining this with an output voltage measuring means such as the diode voltage detecting means of the opposite diode shown at 24 for measuring the output voltage of the converter circuit, the temperature of the power semiconductor can be estimated. Also, using the same component, not only the voltage drop at the time of current flow but also the recovery voltage of the diode at the time of reverse bias as in Example 8 is detected, and the output signal to the third AND circuit shown in FIG. If it can be generated, the temperature estimation parts of the power semiconductor such as the thermistor and the thermometer are deleted in the configuration shown in the embodiment 8, and the number of parts is reduced while reducing the loss of the power semiconductor in addition to the initial suppression of the diode EMI. Can be reduced.

  An example of a suitable drive circuit configuration of the variable gate resistors 3 and 16 for changing the impedance of the gate for driving the power semiconductor will be described with reference to FIG.

  In this embodiment, a gate drive power supply circuit is connected to the IGBT, and a drive signal generating means and a transistor are provided, and the gate impedance at the time of turn-on and the time at the turn-off are obtained by using the switching circuit operating in a complementary manner. 1 is an example of a circuit configuration using a power transistor capable of independently setting the gate impedance, a gate driving circuit for driving the power transistor, and a pulse generation unit.

  The configuration of FIG. 10 will be described. The same components as those in FIG. 9 are denoted by the same reference numerals. 26 is a first PMOSFET, 51 is a first inverting amplifier, 28 is a first gate resistor, 29 is a second gate resistor, 30 is a turn-on AND circuit, 31 is a third gate resistor, and 32 is a DC power supply , 33 are first npn transistors, 34 is a first pnp transistor, and 35 is a turn-off impedance.

  In FIG. 10, when the IGBT is turned on, the resistance between the DC power supply 32 and the IGBT 1 is normally the first PMOSFET 26 turned on, and the first gate resistance 28 and the second gate resistance connected in parallel. 29 and the combined resistance (R1 × R2) / (R1 + R2) + R3 of the third gate resistor 31 connected in series with the two resistors. When a signal for loosening the gate is input in the gain change signal generation unit 7, the first PMOSFET is turned off, so that the combined resistance at this time is R1 + R3 and the combined resistance (R1 × R2) / By changing the resistance greatly with respect to (R1 + R2) + R3, it is possible to provide the variable gate resistors 3 and 16 shown in the respective embodiments described above.

  An example of a suitable drive circuit configuration of the variable gate resistors 3 and 16 for changing the impedance of the gate for driving the power semiconductor will be described with reference to FIG.

  This embodiment is an example of a circuit that can change the gate resistance after turn-on transiently by feeding back the gate voltage to the IGBT at turn-on. The same components as those in FIG. 10 are denoted by the same reference numerals. Reference numeral 36 denotes a first turn-on change signal comparator, 37 denotes a first inverter circuit, and 42 denotes a fourth gate resistance.

  In FIG. 11, when the IGBT is turned on, the gate voltage is passed through the fourth gate resistor 42 and the first inverter circuit 37, and the output of the gain change signal generator 7 and the first turn-on change signal comparator 36 are used. Compared. With this circuit configuration, the gate impedance described in the tenth embodiment can be changed, and the same effect as in the fifth embodiment can be obtained.

  An example of a suitable drive circuit configuration of the variable gate resistors 3 and 16 for changing the impedance of the gate for driving the power semiconductor will be described with reference to FIG.

  This embodiment is an example of a circuit that can change the gate resistance after turn-on transiently by feeding back the gate voltage to the IGBT at turn-on. The same components as those in FIG. 10 are denoted by the same reference numerals. Reference numeral 38 denotes a second turn-on change signal comparator, 39 denotes a second PMOSFET, 40 denotes a fifth resistor, and 41 denotes a first capacitor.

  In FIG. 12, after changing the combined resistance from R1 + R3, which is larger than the combined resistance (R1 × R2) / (R1 + R2) + R3, in the same manner as shown in Example 10 when turning on the IGBT, The voltage rise of the diode 12 is compared with the information of the diode voltage measuring means as indicated by 19 and the signal of the gain change signal generator 7, and is output by the second turn-on change signal comparator indicated by 38. , 39, the gate impedance can be changed from R1 + R3 to R3 + (R1 × R5) / (R1 + R5).

  By selecting a constant applied to the fifth resistor 40, the same effect as that described in the ninth embodiment can be obtained.

  Further, by adopting a circuit configuration in which the first capacitor 41 is connected in parallel with the fifth resistor 40, the impedance immediately after the second PMOSFET 39 is turned on is reduced, and the switching element 1 is instantaneously turned on. It is possible to increase the rate and reduce the loss of the switching element. The effect at this time is the same as the effect described in the seventh embodiment.

  It is an example of the variable gate drive circuit which changes the impedance of the gate which drives a power semiconductor.

  In this embodiment, the drive signal generating means shown in 27 is combined with the transistors shown in 33, 34, 49, and 50 to form a two-parallel inverter circuit, and the gate voltage is fed back when the IGBT is turned on. This is an example of a circuit that can change the gate resistance after turn-on transiently. The same components as those in FIG. 12 are denoted by the same reference numerals. Reference numeral 27 denotes a drive signal generating means, 24 a first NMOSFET, 37 a first inverting amplifier, 28 a first gate resistor, 27 a seventh gate resistor, and 36 a turn-on change signal comparison. The reference numeral 47 denotes a gate resistance of 6, and 31 denotes a third gate resistance.

  In FIG. 13, when the IGBT is turned on, the combined resistance is changed from R1 to a combined resistance (R1 × R7) / (R1 + R7) that is smaller than R1 by the same method as that of the embodiment 10 or the embodiment 12. It is an example of the circuit to switch.

  In this embodiment, the gate of the first NMOSFET indicated by 24 is turned on by a turn-on change signal indicated by 36 by the signal of the gain change signal generating part indicated by 7 based on the information from the temperature estimating means for power semiconductor 6. This is a circuit system in which the circuit impedance to be driven transiently is changed through a logic circuit comprising a comparator for use and an inverting amplifier indicated by 37. Similar to the twelfth embodiment, it is possible to appropriately control the impedance necessary for driving the gate drive circuit based on the temperature information of the power semiconductor.

  By selecting suitable constants for the impedances of the gate resistors 27 and 26 and the determination value of the signal generator 7, the same effect as that described in the ninth embodiment can be obtained.

  FIG. 14 shows a system configuration diagram in the case where noise generation conditions are distributed in the pulse output unit when the present invention is applied to a three-phase motor and a three-phase inverter.

  The same components as those in the drawings up to FIG. 13 are denoted by the same reference numerals. 52 shows a three-phase motor, 43 shows a phase current detection means, 44 shows a pulse control unit, 45 shows a gate drive unit and 46 shows a three-phase inverter circuit.

  In a three-phase motor drive system that performs PWM control, information generated by a pulse control unit 44 constituted by a microcomputer or a logical CPU is obtained based on information from phase current detection means 43 constituted by a current sensor or the like. This is transmitted to the gate drive unit 45. Based on the temperature information obtained from the power semiconductor temperature estimation means 6, the pulse output generation unit 7 distributes noise generation conditions. At this time, it is possible to solve the problem of the present invention by adjusting the gate impedance between the drive circuit and the switching element in the gate drive unit at a temperature or PWM pulse condition at which the diode EMI is likely to occur.

  In addition, when the gate drive system of a semiconductor converter system for driving a railway vehicle or an electric vehicle to which the embodiment is applied is used, the EMI is reduced at a low temperature, or in a specific operation condition such as a cold district or at a start time. There is an effect that it is possible to prevent element destruction due to the resonance phenomenon of the diode, inverter failure, etc., leading to improved reliability.

  The above-mentioned idea that does not deviate from the preferred embodiment and the combined idea of the preferred embodiment can be easily deduced from the present invention.

  In the embodiment of the present invention described above, a converter circuit including a two-level inverter is illustrated. However, for the converter circuit of the present invention, a multi-level inverter or converter having three or more voltage levels, or a DC -It is applicable also to other converters, such as a DC converter.

  It is applicable to various fields that use power converters such as home appliances, power supplies, motor-driven railways, steel, and electric power.

DESCRIPTION OF SYMBOLS 1 Switching element 2 Diode 3 Variable gate resistance 4 Gate drive circuit 5 Pulse generation part 6 Power semiconductor temperature estimation means 7 Gain change signal generation part 8 1st AND circuit 9 1st pulse width detection circuit 10 1st comparator 11 Delay circuit 12 Positive terminal 13 Negative terminal 14 Second switching element 15 Second diode 16 Second variable resistor 17 Second gate drive circuit 18 Output terminal 19 Second gain change signal generator 20 Second AND circuit 21 Second pulse width detection circuit 22 Second comparator 23 Third AND circuit 24 Diode voltage detection means 25 Current detection means 26 First PMOSFET
27 drive signal generating means 28 first gate resistor 29 second gate resistor 30 turn-on AND circuit 31 third gate resistor 32 DC power supply 33 first npn transistor 34 first pnp transistor 35 turn-off impedance 36 first Turn-on change signal comparator 37 First inverter circuit 38 Second turn-on change signal comparator 39 Second PMOSFET
40 fifth resistor 41 first capacitor 42 fourth gate resistor 43 phase current detecting means 44 pulse control unit 45 gate drive unit 46 three-phase inverter circuit 47 sixth gate resistor 48 seventh gate resistor 49 second npn transistor 50 second pnp transistor 51 inverting amplifier 52 three-phase motor 101 combination diode

Claims (3)

A gate driving circuit for driving the gate of the voltage-driven semiconductor switching element; and a first operating means for switching a gate driving impedance.
Turn-on is started under a predetermined gate driving condition set in advance, and when the switching element is turned on, the first operating means adjusts the gate impedance for a predetermined time at a predetermined timing in accordance with the peak of the collector current. In the gate drive device to enlarge,
A third means for detecting a voltage at the time of recovery of the diode connected to the pair arm of the switching element, and a fourth means for estimating a device temperature of the diode,
The first operating means is based on a comparison between the voltage detected by the third means and the voltage threshold value, and a comparison between the device temperature detected by the fourth means and the temperature threshold value. A gate driving apparatus characterized by determining a predetermined timing for increasing a gate driving impedance.   2. The gate driving device according to claim 1, wherein the first operating means increases the gate driving impedance for a predetermined time by using first means for increasing a resistance value of a gate resistor connected to a gate of the switching element. . The fourth means is connected to the opposite arm side of the switching element operated by the first operating means, and detects a current flowing through the diode that causes reverse recovery when the switching element is turned on.
Means for detecting a forward voltage when reverse recovery occurs as the switching element is turned on;
The gate drive device according to claim 1, further comprising means for calculating an estimated temperature value of the diode chip from the current-voltage characteristics of the diode.

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