JP6887320B2 - Power conversion unit drive circuit and drive method, power conversion unit, and power conversion device - Google Patents

Description

The present invention relates to a drive circuit and a drive method of a power conversion unit that performs power conversion by a semiconductor switching element, a power conversion unit composed of a semiconductor switching element and a drive circuit, and a power conversion device including a plurality of power conversion units.

In a power conversion device such as an inverter device, a power conversion unit in which parts such as a power semiconductor module equipped with a semiconductor switching element, a capacitor, a bus bar, and a gate drive circuit are integrated is configured, and a plurality of these power conversion units are mounted. To improve the output capacity. By using such a power conversion unit, parts can be standardized, and the cost of the power conversion device can be reduced. Here, the capacity of the power conversion device is increased by increasing the number of parallel power conversion units.

When the power conversion units are connected in parallel, the current value flowing through the semiconductor switching element becomes unbalanced due to variations in characteristics such as the gate threshold value and the on-voltage of the semiconductor switching element. Therefore, a power conversion unit may be designed by setting the current flowing through the semiconductor switching element to a current value smaller than the rated current, or a semiconductor switching element having similar characteristics may be selected and used from a large number of semiconductor switching elements. To do. However, increasing the capacity and reducing the cost of the power conversion device by connecting the power conversion units in parallel is limited.

On the other hand, as described in Patent Document 1 and Patent Document 2, for example, a conventional technique for reducing current imbalance by driving control of a semiconductor switching element is known.

In the technique described in Patent Document 1, a variable gate resistance circuit is provided in a drive circuit of an IGBT, and each variable gate resistance circuit is controlled according to a time lag of current pulses flowing through a plurality of IGBTs. Each gate resistance at the start of turn-on / turn-off control is changed.

In the technique described in Patent Document 2, each voltage of the drive control power supply and the emitter potential generation power supply in the drive circuit of the semiconductor switching element is displaced by an equal amount according to the difference between the gate threshold voltage and the gate threshold voltage reference value. To do.

Japanese Unexamined Patent Publication No. 2014-230307 Japanese Unexamined Patent Publication No. 2008-178248

In the technique of Patent Document 1, if the gate resistance value is different, the temperature dependence of the switching timing becomes large, so that it is difficult to improve the accuracy or reliability of reducing the current imbalance.

Further, in the technique of Patent Document 2, since each voltage of the drive control power supply and the emitter potential generation power supply is adjusted, the configuration of the gate drive circuit becomes complicated and the circuit adjustment is difficult. Therefore, it is difficult to improve the accuracy or reliability of reducing the current imbalance.

Therefore, in the present invention, a drive circuit and a drive method of a power conversion unit capable of improving the accuracy or reliability of reducing current imbalance, a power conversion unit provided with such a drive circuit, and a plurality of power conversion units are arranged in parallel. Provide a power converter to be connected.

In order to solve the above problems, the drive circuit of the power conversion unit according to the present invention is provided in the power conversion unit that performs power conversion by the semiconductor switching element, drives the semiconductor switching element, and is provided to the semiconductor switching element. It is equipped with a voltage variable circuit unit that outputs the drive voltage for control, and when a plurality of power conversion units are connected in parallel and semiconductor switching elements are connected in parallel, the drive voltage is applied to each of the plurality of power conversion units. Based on the characteristic map information given by a function that uses the turn-on time as the independent variable and the turn-on time, which is the time from when the voltage of the control terminal of the semiconductor switching element starts to rise to when the current starts to flow through the semiconductor switching element, as the dependent variable. , The target command of the drive voltage corresponding to the target value of the turn-on time common to the plurality of power conversion units is calculated, and the drive voltage is variably controlled so as to be the target command in the voltage variable circuit unit.

In order to solve the above problems, in the method of driving the power conversion unit according to the present invention, a driving voltage for control is applied to the semiconductor switching element to drive the semiconductor switching element, and a plurality of power conversion units are connected in parallel to form a semiconductor. When the switching elements are connected in parallel, the drive voltage is set as an independent variable for each of the plurality of power conversion units, and after the voltage of the control terminal of the semiconductor switching element starts to rise, the current starts to flow in the semiconductor switching element. Based on the characteristic map information given by the function whose dependent variable is the turn-on time, which is the time until, the target command of the drive voltage corresponding to the target value of the turn-on time common to a plurality of power conversion units is calculated and driven. Set the voltage value as the target command.

Further, in order to solve the above problems, the power conversion unit according to the present invention includes a semiconductor switching element and a drive circuit for driving the semiconductor switching element, and performs power conversion by the semiconductor switching element. The circuit includes a voltage variable circuit unit that outputs a control drive voltage given to the semiconductor switching element, and when a plurality of power conversion units are connected in parallel and the semiconductor switching elements are connected in parallel, a plurality of power conversions are performed. A function that uses the drive voltage as an independent variable for each unit and the turn-on time, which is the time from when the voltage at the control terminal of the semiconductor switching element starts to rise to when the current starts to flow through the semiconductor switching element, as the dependent variable. Based on the given characteristic map information, the target command of the drive voltage corresponding to the target value of the turn-on time common to a plurality of power conversion units is calculated, and the drive voltage becomes the target command in the voltage variable circuit unit. It is variably controlled to.

Further, in order to solve the above problems, in the power conversion device according to the present invention, a plurality of power conversion units including a semiconductor switching element and a drive circuit for driving the semiconductor switching element are connected in parallel, and the semiconductor switching element is formed. Each of a voltage variable circuit unit, which is configured by being connected in parallel and is provided in each of a plurality of drive circuits and outputs a control drive voltage given to a semiconductor switching element, and a plurality of voltage variable circuit units. On the other hand, the drive voltage is used as an independent variable, and the turn-on time, which is the time from when the voltage at the control terminal of the semiconductor switching element starts to rise until the current starts to flow through the semiconductor switching element, is given as a dependent variable. Each of the plurality of voltage variable circuit units includes a common control unit that creates a drive voltage target command corresponding to a turn-on time target value common to a plurality of power conversion units based on the characteristic map information to be obtained. , The drive voltage is variably controlled so as to be a target command created by the common control unit for each of the plurality of voltage variable circuit units.

According to the present invention, by setting the value of the drive voltage based on the characteristic map information, the accuracy or reliability of reducing the current imbalance is improved.

Issues, configurations and effects other than those described above will be clarified by the description of the following embodiments.

The block diagram of the drive circuit of the power conversion unit which is Example 1 is shown. An example of a gate voltage waveform and an example of a main current waveform of a semiconductor switching element driven by the drive circuit of the first embodiment are shown. An example of a circuit configuration of a variable voltage source included in the drive circuit of the first embodiment is shown. It is a flowchart which shows the driving method of the power conversion unit executed in Example 1. FIG. The block diagram of the drive circuit of the power conversion unit which is Example 2 is shown. The block diagram of the drive circuit of the power conversion unit which is Example 3 is shown. The block diagram of the drive circuit of the power conversion unit which is Example 4 is shown. An example of a turn-on waveform in a power conversion device to which the drive circuit according to the fifth embodiment is applied is shown. The relationship between the temperature of the semiconductor switching element and the unbalance rate of the turn-on loss (Eon) in Example 5 is shown.

Hereinafter, embodiments of the present invention will be described with reference to the drawings according to Examples 1 to 5. In each figure, those having the same reference number or name indicate the same constituent requirements or constituent requirements having similar functions.

FIG. 1 shows a block diagram of a drive circuit of a power conversion unit according to a first embodiment of the present invention. An example of the gate voltage waveform and an example of the main current waveform are shown together.

The power conversion unit 111 and the power conversion unit 112 constitute a current conversion device. The power conversion unit 111 and the power conversion unit 112 are connected in parallel to each other and are controlled by the common control unit 6. The number of parallel power conversion units is not limited to two, and may be a plurality of power conversion units depending on the power capacity of the power conversion device.

The power conversion unit 111 is composed of a semiconductor switching element 301 for power and a drive circuit 501. The power conversion unit 112 is composed of a semiconductor switching element 302 for power and a drive circuit 502. The semiconductor switching element 301 and the semiconductor switching element 302 are mounted on the power module together with the recirculation diode, respectively.

In the first embodiment, IGBTs (Insulated Gate Bipolar Transistors) are used as the semiconductor switching elements 301 and 302. Not limited to the IGBT, a power MOSFET (Metal Oxide Semiconductor Field Effect Transistor) or the like may be used. Further, the semiconductor switching elements 301 and 302 may be composed of a plurality of semiconductor element chips connected in parallel on a circuit board like a general power module.

When the power conversion unit 111 and the power conversion unit 112 are connected in parallel, the semiconductor switching element 301 and the semiconductor switching element 302 are connected in parallel. The semiconductor switching elements 301 and 302 are driven by the drive circuit 501 and the drive circuit 502, respectively. The drive circuit 501 and the drive circuit 502 are individually controlled so as to output a gate drive voltage for on / off control to the semiconductor switching elements 301 and 302, respectively.

The drive circuit 501 and the drive circuit 502 each include a gate voltage variable circuit unit 55. As a result, the drive circuit 501 and the drive circuit 502 individually control the gate voltage variable circuit unit 55 in response to the same input signal 21, so that the gate voltages of different waveforms are applied to the gates of the semiconductor switching element 301 and the semiconductor switching element 302. Can be applied.

The gate voltage variable circuit unit 55 is composed of a variable voltage source 10, a charging switch 22, a charging resistor 24, a discharging switch 23, and a discharging resistor 25. In the first embodiment, MOSFETs are used as the charging switch 22 and the discharging switch 23. Not limited to MOSFETs, junction-type bipolar transistors and the like may be used.

The gate voltage variable circuit unit 55 complementaryly controls the charging switch 22 and the discharging switch 23 on and off according to the input signal 21, so that the gate output terminal 13 has substantially the same potential as the positive bias terminal 11. Or set to substantially the same potential as the negative bias terminal 12 (reference potential in the first embodiment). As a result, the capacitance between the gate and the emitter of the semiconductor switching elements 301 and 302 is charged and discharged, and the semiconductor switching elements 301 and 302 are turned on and off.

More specifically, when an on command signal is given as the input signal 21, the charging switch 22 is turned on and the discharging switch 23 is turned off, so that the voltage of the variable voltage source 10 is changed to the charging switch 22. And is applied between the gate and emitter of the semiconductor switching element via the charging resistor 24. As a result, the capacitance between the gate and the emitter of the semiconductor switching element is charged, and the semiconductor switching element is turned on. Here, the potential of the emitter is substantially the same as the potential (reference potential) of the negative bias terminal 12.

Further, when an off command signal is given as the input signal 21, the discharge switch 23 is turned on and the charging switch 22 is turned off, so that the discharge switch 23 and the discharge resistor 25 cause the gate of the semiconductor switching element. -The emitters are short-circuited. As a result, the charge charge of the capacitance between the gate and the emitter of the semiconductor switching element is discharged, and the semiconductor switching element is turned off.

Further, the drive circuit 501 and the drive circuit 502 each include a characteristic map recording means 51 for recording information regarding the characteristics of the semiconductor switching element 301 and the semiconductor switching element 302, respectively. As the characteristic map recording means 51, for example, a memory element or a two-dimensional bar code can be applied.

The characteristic map recording means 51 of the power conversion unit 111 records characteristic map information 31 indicating the relationship between the gate (drive) voltage Vge of the semiconductor switching element 301 and the switching characteristics (“turn-on time” in the first embodiment). There is. Further, the characteristic map recording means 51 in the power conversion unit 112 records similar characteristic map information 32 regarding the semiconductor switching element 302. Here, the gate (drive) voltage in the characteristic map information of the first embodiment is a voltage peak value (Vge1, Vge2) in the gate voltage (gate-emitter voltage) waveform, and is a power supply output by the variable voltage source 10. Corresponds to the voltage value.

In the first embodiment, the characteristic map information is given by a function (“linear function” in FIG. 1) in which the gate (driving) voltage Vge is an independent variable and the turn-on time is a dependent variable. This function can be obtained by statistical modeling such as regression analysis from a large number of data obtained by measuring the turn-on time while changing the gate drive voltage, for example.

The characteristic map information is not limited to a function but may be table data or the like as long as it is information indicating a change in switching characteristics (turn-on time, etc.) with respect to a change in gate drive voltage.

The common control unit 6 acquires the characteristic map information 31 recorded in the characteristic map recording means 51 in the power conversion unit 111 by the reading means 511. Further, the common control unit 6 acquires the characteristic map information 32 recorded in the characteristic map recording means 51 in the power conversion unit 112 by the reading means 512. If the characteristic map recording means 51 is a memory element, the reading means is a data reading function of the common control unit 6. If the characteristic map recording means 51 is a two-dimensional bar code or the like, the reading means is a bar code reader or the like.

The common control unit 6 calculates the gate voltage target command 551 (Vge1) of the semiconductor switching element 301 corresponding to the target value 30 which is a predetermined value of the switching characteristic based on the characteristic map information 31 acquired by the reading means 511. To do. Further, the common control unit 6 receives a gate voltage target command 552 (Vge2) of the semiconductor switching element 302 corresponding to the target value 30 common to the semiconductor switching element 301 based on the characteristic map information 32 acquired by the reading means 512. Is calculated.

Further, the common control unit 6 transmits the gate voltage target command 551 and the gate voltage target command 552 created by calculation to the gate voltage variable circuit unit 55 of the drive circuit 501 and the gate voltage variable circuit unit 55 of the drive circuit 502, respectively. To do. As a result, the output voltage of the variable voltage source 10 in the gate voltage variable circuit unit 55 included in the drive circuit 501 is set in the gate voltage target command 551. Further, the output voltage of the variable voltage source 10 in the gate voltage variable circuit unit 55 included in the drive circuit 502 is set in the gate voltage target command 552. Thereby, the gate drive voltage applied to each gate to the semiconductor switching elements 301 and 302 can be individually controlled (for example, Vge1> Vge2 can be set as shown in the figure).

In the first embodiment, the switching characteristics of the semiconductor switching elements 301 and 302 are different as shown by the characteristic map informations 31 and 32, but the drive circuit as described above makes it possible to perform the switching at the time of switching as shown in the main current waveform example. Current flows through the semiconductor switching elements 301 and 302 almost evenly. That is, the current imbalance in the semiconductor switching elements 301 and 302 is prevented.

The operation of the first embodiment will be described in detail below.

FIG. 2 shows an example of a gate voltage waveform (Vge1> Vge2) and an example of a main current waveform ((b)) of a semiconductor switching element driven by the drive circuit of the first embodiment. For comparison, an example of the gate voltage waveform and an example of the main current waveform ((a)) are also shown when the gate applied voltage is substantially the same (Vge1 = Vge2).

As described above, the semiconductor switching elements 301 and 302 in the first embodiment have different switching characteristics. That is, as the characteristic map informations 31 and 32 in FIG. 1 show, the semiconductor switching element 301 has a slower turn-on than the semiconductor switching element 302 for the same gate voltage value. It should be noted that such variations in switching characteristics are caused by variations in the gate threshold voltage, variations in the junction structure such as the impurity concentration profile, and the like.

Here, the turn-on time is the time from the start time of the rise of the gate voltage (t0) to the start time of the rise of the main current (t1a, t1b). Therefore, when Vge1 = Vge2 ((a)), the turn-on time of the semiconductor switching element 301 is "t1b-t0", the turn-on time of the semiconductor switching element 302 is "t1a-t0", and the semiconductor switching element 301 The turn-on time is longer than that of the semiconductor switching element 302. That is, the semiconductor switching element 301 has a slower turn-on than the semiconductor switching element 302. Therefore, the current tends to be concentrated on the semiconductor switching element 302 that turns on quickly, and the main current I2 of the semiconductor switching element 302 becomes larger than the main current I1 of the semiconductor switching element 301 at the time of switching. That is, an imbalance occurs in the main currents I1 and I2, and an imbalance occurs in the power loss of the semiconductor switching element.

On the other hand, in the case of Vge1> Vge2 ((b)) as in the first embodiment, the turn-on of the semiconductor switching element 301 is relatively accelerated, and the turn-on of the semiconductor switching element 302 is delayed. Therefore, the turn-on times of the semiconductor switching elements 301 and 302 are substantially the same (t1-t0), so that the main currents I1 and I2 are substantially the same and balanced.

FIG. 3 shows a circuit configuration example of the variable voltage source 10 in the gate voltage variable circuit unit 55 included in the drive circuit of the first embodiment.

As shown in FIG. 3, the variable voltage source 10 includes an isolation transformer 400, a DC / DC controller 516 connected to the primary winding of the isolation transformer 400, and a diode connected to the secondary winding of the isolation transformer 400. The rectifier 401 and the potential meter (variable resistance) 430 for setting the output voltage value of the variable voltage source 10 are configured as main components.

Here, the DC / DC controller 516 includes a semiconductor switch constituting an inverter connected to the primary winding of the isolated transformer 400, and a control circuit that supplies DC power to the inverter and controls the semiconductor switch. , Along with other parts, constitutes a DC / DC converter circuit that is a main circuit portion of the variable voltage source 10. The control circuit included in the DC / DC controller 516 or the DC / DC controller 516 may be an integrated circuit.

A DC voltage on the primary side is applied from a DC power supply (not shown) between the terminals of the primary side positive power input terminal 518 and the primary side negative power input terminal 517, that is, between the DC input terminals of the DC / DC controller 516. The DC / DC controller 516 transmits the power input from the DC power supply to the secondary side via the isolation transformer 400. The transmitted power is stored in the capacitor 402 via the diode rectifier 401. As a result, the secondary side DC voltage is output between the terminals of the secondary side positive bias terminal 11 and the negative bias terminal 12. Further, the potential of the intermediate potential terminal 14 is set by the constant voltage diode 404 and the resistor 403.

A part of the electric power transmitted by the DC / DC controller 516 is stored in the capacitor 432 via the auxiliary winding of the isolation transformer 400 and the rectifier diode 433 connected to the auxiliary winding. The voltage across the capacitor 402 is proportional to the voltage across the capacitor 432.

A potentiometer 430 including a feedback terminal 431 is connected to both ends of the capacitor 432 in order to give a command to the DC / DC controller 516 to control the output voltage of the variable voltage source 10. The voltage across the capacitor 432 is resistance divided by the feedback terminal 431, and the resistance voltage division ratio is controlled by a command signal given to the potentiometer control terminal 434. Therefore, by controlling the resistance voltage division ratio of the potentiometer 430, the voltage between the positive bias terminal 11 and the negative bias terminal 12, that is, the output voltage of the variable voltage source 10 can be controlled.

In the first embodiment, the command signal given to the potentiometer control terminal 434 is the above-mentioned gate voltage target command 551,552 transmitted from the common control unit 6. Since the resistance voltage division ratio of the potentiometer 430 is set according to the gate voltage target commands 551 and 552, the variable voltage source 10 outputs the power supply voltage of the gate drive voltage value indicated by the gate voltage target command.

FIG. 4 is a flowchart showing a driving method of the power conversion unit executed in the first embodiment.

First, as an initial condition, information (characteristic map information) regarding the gate voltage dependence of the switching timing is recorded in the power unit (power conversion units 111 and 112) (step S1).

Next, the common control unit 6 acquires the characteristic map information from the power conversion unit (step S2).

Next, in the common control unit 6, the gate (drive) voltage of each power conversion unit having substantially the same switching timing is calculated from the acquired characteristic map information (step S3).

Next, a gate voltage target command indicating the calculated value of each gate (drive) voltage is transmitted from the common control unit 6 to the gate voltage variable circuit unit 55 mounted on each drive circuit (step S4).

Next, the gate voltage variable circuit unit 55 drives the semiconductor switching element with the gate (drive) voltage corresponding to the gate voltage target command (step S5).

As described above, according to the first embodiment, the gate drive voltage output by the drive circuit is variable based on the characteristic map information indicating the relationship between the gate drive voltage and the switching characteristic, which is recorded in advance in the characteristic map recording means. Therefore, the accuracy or reliability of reducing the current imbalance of a plurality of power semiconductor switching elements is improved. Further, the drive circuit has a variable voltage source that is pre-recorded in the characteristic map recording means and is controlled according to a gate voltage target command created based on the characteristic map information indicating the relationship between the gate drive voltage and the switching characteristic. Therefore, the gate drive voltage of each power semiconductor switching element can be adjusted easily and with high accuracy.

FIG. 5 shows a block diagram of a drive circuit of a power conversion unit according to a second embodiment of the present invention. Hereinafter, the points different from those of the first embodiment will be mainly described.

In the second embodiment, the characteristic map information 31, 32 (FIG. 1) of the semiconductor switching element for power in the power conversion unit is referred to from the database 201.

As shown in FIG. 5, characteristic map information showing the relationship between the switching characteristics and the gate drive voltage in each semiconductor switching element is stored in the database 201. The power conversion unit 111 and the power conversion unit 112 are associated with the characteristic map information on the database 201 by identification means such as product barcodes and serial numbers assigned to them.

When the power conversion unit 111 and the power conversion unit 112 are connected in parallel, the computer 203 uses the reading means 202 to obtain the characteristics associated with the identification means assigned to the power conversion unit 111 and the power conversion unit 112 from the database 201. Get map information. The computer 203 calculates each gate drive voltage for the same switching characteristic based on the acquired characteristic map information. Then, the computer 203 transmits each of the calculated gate drive voltages to the host controller 205 by the transmission means 204. The host controller 205 creates gate voltage target commands 551 and 552 according to the value of the gate drive voltage transmitted from the computer 203, and sends the created gate voltage target command 551 to the gate voltage variable circuit unit 55 of the power conversion unit 111. And transmits the created gate voltage target command 552 to the gate voltage variable circuit unit 55 of the power conversion unit 112.

Each gate voltage variable circuit unit 55 of the power conversion unit 111 and the power conversion unit 112 sets the gate power supply voltage to the value of the gate voltage target command transmitted from the host controller 205, and performs semiconductor switching while synchronizing with the input signal 21. The element 301 and the semiconductor switching element 302 are individually driven and controlled.

In the fifth embodiment, the gate voltage variable circuit unit 55 holds the gate voltage target command transmitted from the host controller 205. As a result, after the output voltage of the gate voltage variable circuit unit 55 is set to the value of the gate voltage target command, the power conversion unit 111 does not depend on the state of the host controller 205 or the transmission means 204, for example, even if they stop. And the output voltage value of the gate voltage variable circuit unit 55 of the power conversion unit 112 is maintained at a value corresponding to the gate voltage target command.

According to the second embodiment, the gate drive voltage is controlled based on the characteristic map information recorded in the database. Therefore, as in the first embodiment, the accuracy of reducing the current imbalance of the plurality of power semiconductor switching elements or Improves reliability. Further, since the characteristic map information is acquired from the database, it becomes easy to adjust the circuit for suppressing the current imbalance in the plurality of power conversion units at the time of installation or maintenance of the power conversion device.

FIG. 6 shows a block diagram of a drive circuit of a power conversion unit according to a third embodiment of the present invention. Hereinafter, the points different from those of the first embodiment will be mainly described.

The power conversion unit 111 includes a power module 305 having an upper and lower arm, a drive circuit 503 for driving the semiconductor switching element 303 of the upper arm, and a drive circuit 501 for driving the semiconductor switching element 301 of the lower arm. Further, the power conversion unit 112 includes a power module 306 including upper and lower arms, a drive circuit 504 for driving the semiconductor switching element 304 of the upper arm, and a drive circuit 502 for driving the semiconductor switching element 302 of the lower arm.

The power conversion unit 111 and the power conversion unit 112 are connected in parallel to form one phase of the main circuit of the power conversion device (for example, an inverter). When the power conversion unit 111 and the power conversion unit are connected in parallel, the semiconductor switching elements 303 and 304 of the upper arm are connected in parallel, and the semiconductor switching elements 301 and 302 of the lower arm are connected in parallel.

Each high potential side of the semiconductor switching elements 303 and 304 of the upper arm is connected to the DC terminal (positive electrode) 601. Each low potential side of the semiconductor switching elements 301 and 302 of the lower arm is connected to the DC terminal (negative electrode) 602. The series connection points of the upper and lower arms, that is, the low potential sides of the semiconductor switching elements 303 and 304 of the upper arm and the high potential sides of the semiconductor switching elements 301 and 302 of the lower arm are connected to the output terminal 603.

The circuit configurations of the drive circuits 501, 502, 503 and 504 are the same. Therefore, in the following, the drive circuits 501 and 502 for the lower arm will be described in detail, and the drive circuits 503 and 504 for the upper arm will be described schematically.

As shown in FIG. 6, the drive circuits 501 and 502 include a recording means 51 (corresponding to the “characteristic map recording means” in FIG. 1), an interface (I / F) circuit unit 52, and a gate voltage gradient variable circuit unit 54. And the gate voltage variable circuit unit 55 is provided.

Each recording means 51 of the drive circuits 501 and 502 records characteristic map information indicating the relationship between the switching characteristics of the semiconductor switching elements 301 and 302 of the lower arm and the gate drive voltage, respectively. The characteristic map information recorded by the recording means 51 is preferably acquired by a test inspection at the time of shipping inspection of the power module or the semiconductor switching element.

The characteristic map information of the semiconductor switching elements 301 and 302 is read from the recording means 51 by the gate voltage calculating means 60. The gate voltage calculating means 60 calculates the gate drive voltage of each of the semiconductor switching elements 301 and 302 corresponding to the target value of the switching characteristic based on the read characteristic map information. The common control unit 6 creates a gate voltage target command according to the gate drive voltage calculated by the gate voltage calculation means 60 and individually transmits the gate voltage target command to the drive circuits 501 and 502. The gate voltage target command received by the drive circuits 501 and 502 is transmitted to the gate voltage gradient variable circuit unit 54 and the gate voltage variable circuit unit 55 via the interface circuit unit 52.

The gate voltage variable circuit unit 55 sets the gate drive voltage in response to the gate voltage target command, as in the first embodiment. As a result, the current imbalance in the semiconductor switching elements 301 and 302 is surely prevented.

In a power module equipped with upper and lower arms, the parasitic inductance and capacitance in the circuit, the junction structure of the semiconductor switching element, and the switching characteristics combine to cause current or voltage ringing when the semiconductor switching element is turned on and off. A surge occurs. Therefore, in the third embodiment, the resistance value of the gate resistance (corresponding to the charging resistance 24 or the discharging resistance 25 in FIG. 1) is variably changed according to the gate voltage target command by the gate voltage gradient variable circuit unit 54. By setting, the gradient (increasing rate or decreasing rate) of the gate-emitter voltage when the gate-emitter voltage rises or falls is adjusted.

As a result, even if the circuit state is such that current or voltage ringing or surge is likely to occur in the semiconductor switching elements 301 and 302 with respect to the value of the gate drive voltage set in the drive circuit to suppress the current imbalance, the semiconductor It is possible to suppress the generation of current or voltage ringing and surge in the switching elements 301 and 302.

The configuration and operation of the upper arm drive circuits 503 and 504 are the same as those of the lower arm drive circuits 501 and 502 described above. Therefore, the current imbalance in the semiconductor switching elements 303 and 304 of the upper arm is surely prevented. Further, when the gate-emitter voltage rises or falls, it is possible to suppress the occurrence of current or voltage ringing or surge in the semiconductor switching elements 303 and 304 of the upper arm.

As described above, according to the third embodiment, the gate drive voltage is controlled based on the characteristic map information. Therefore, as in the first embodiment, the accuracy of reducing the current imbalance of the plurality of power semiconductor switching elements or Improves reliability. Furthermore, the inconvenience that current or voltage ringing or surge in a plurality of modularized switching elements increases with the setting of the gate drive voltage for suppressing the current imbalance is a gate voltage target command, that is, gate drive. This is prevented by controlling the slope of the gate voltage according to the voltage.

FIG. 7 shows a block diagram of a drive circuit of a power conversion unit according to a fourth embodiment of the present invention. In the fourth embodiment, the temperature sensor 67 and the temperature detection unit 68 are added to the circuit configuration of the third embodiment described above. Hereinafter, the points different from those of the third embodiment will be mainly described.

As shown in FIG. 7, the temperature sensor 67 is mounted on the power modules 305 and 306. As the temperature sensor 67, for example, a thermocouple, a temperature sense diode, a thermistor, or the like is applied.

Generally, the switching characteristics of a semiconductor switching element change with temperature. Therefore, in the fourth embodiment, the gate (power supply) voltage is set based on the temperature detection value of the semiconductor switching element by the temperature sensor 67 in addition to the characteristic map information of the semiconductor switching element.

Hereinafter, the drive circuits of the semiconductor switching elements 301 and 302 of the lower arm will be described, but the operation and configuration of the drive circuits of the semiconductor switching elements 303 and 304 of the upper arm are the same as those of the drive circuits of the semiconductor switching elements 301 and 302 of the lower arm. Is.

The temperature detection unit 68 detects the temperature of the semiconductor switching elements 301 and 302 based on the detection signal of the temperature sensor 67, and transmits the temperature detection value to the gate voltage calculation means 60. The gate voltage calculating means 60 switches based on the characteristic map information of the semiconductor switching elements 301 and 302 read from the recording means 51 and the temperature detection values of the semiconductor switching elements 301 and 302 transmitted from the temperature detection unit 68. The gate drive voltage of each of the semiconductor switching elements 301 and 302 corresponding to the target value of the characteristic is calculated.

Here, in the recording means 51 in the fourth embodiment, in addition to the characteristic map information indicating the relationship between the gate drive voltage and the switching characteristic, the information indicating the temperature dependence of the switching characteristic is also recorded. For example, characteristic map information is recorded for multiple temperature values (eg, room temperature (25 ° C.) and high temperature (125 ° C.)). In this case, the gate voltage calculating means 60 selects the characteristic map information corresponding to the temperature detection value from the plurality of characteristic map information having the temperature of the semiconductor switching element as a parameter, and gates based on the selected characteristic map information. Calculate the drive voltage.

Each of the plurality of characteristic map information with the temperature of the semiconductor switching element as a parameter is given by a function having the gate drive voltage and the switching characteristic as variables, or is given by table data, as in the first embodiment. The characteristic map information may be given by a multivariable function having temperature and gate voltage as independent variables and switching characteristics as dependent variables. Such a multivariable function form is obtained by statistical modeling from a large number of data obtained by measuring switching characteristics (eg, turn-on time) while changing the temperature and gate drive voltage.

As described above, according to the fourth embodiment, the characteristic map information includes the information indicating the temperature dependence of the switching characteristics, so that the current imbalance is surely suppressed even if the temperature of the semiconductor switching element changes. can do.

FIG. 8 shows an example of a turn-on waveform of a semiconductor switching element in a power conversion device to which the drive circuit according to the fifth embodiment of the present invention is applied. The configuration of the drive circuit and the power conversion device is the same as that of the first embodiment, but in the fifth embodiment, a power module of 650 to 750V, 400 to 600A class is used.

FIG. 8 shows an example of turn-on waveforms of the semiconductor switching elements 301 and 302 at room temperature (25 ° C.) and high temperature (125 ° C.). For comparison, an example of a turn-on waveform when a known technique (for example, see Patent Document 1 described above) for adjusting the switching characteristic by the gate resistance while keeping the gate power supply voltage (Vge1≈Vge2) constant is also described.

In the case of adjusting the switching characteristics by the gate resistance ((a)), even if the currents I1 and I2 are substantially balanced at 125 ° C., the current I1 of the semiconductor switching element 301 and the current I2 of the semiconductor switching element 302 are at 25 ° C. It is unbalanced. This is mainly due to the temperature dependence of the resistance value of the gate resistor.

On the other hand, when the switching characteristic is adjusted by the gate (power supply) voltage as in the fifth embodiment ((b)), I1 and I2 are substantially balanced at both 25 ° C. and 125 ° C.

FIG. 9 shows the relationship between the temperature (Temperature) of the semiconductor switching element and the unbalance rate of the turn-on loss (Eon) in the fifth embodiment. For comparison, the same relationship when a known technique for adjusting switching characteristics by a gate resistance is applied is also described.

As shown in FIG. 9, when the switching characteristics are adjusted by the gate resistance ((a)), the unbalance rate 701 of the turn-on loss in the semiconductor switching element 301 and the unbalance rate 702 of the turn-on loss in the semiconductor switching element 302 are determined. It changes greatly when the temperature changes.

On the other hand, when the switching characteristic is adjusted by the gate (power supply) voltage as in the fifth embodiment ((b)), the unbalance rate 701 of the turn-on loss in the semiconductor switching element 301 and the turn-on in the semiconductor switching element 302 The loss imbalance rate 702 hardly changes even if the temperature changes.

By controlling the gate drive voltage in this way, the share of the current or power loss of the semiconductor switching elements connected in parallel can be made uniform with low temperature dependence. Therefore, it is possible to prevent the life of the power conversion device from being shortened or the maintenance frequency of the power conversion device from being increased due to the failure or deterioration of some of the power conversion units. Therefore, the reliability of the power conversion device in which a plurality of power conversion units are connected in parallel is improved. Further, the likelihood of the power capacity of the power conversion unit can be reduced, the likelihood of the power conversion device can be reduced, and the number of parallel power conversion units can be reduced. Therefore, the device size and cost of the power conversion unit and the power conversion unit can be reduced.

The present invention is not limited to the above-described embodiment, and includes various modifications. For example, the above-described embodiment has been described in detail in order to explain the present invention in an easy-to-understand manner, and is not necessarily limited to the one including all the described configurations. Further, it is possible to add / delete / replace a part of the configuration of each embodiment with another configuration.

For example, the number of parallel semiconductor switching elements is not limited to two parallels, and may be any number of two or more parallels.

Further, as the power conversion device, various types such as a DC / AC converter, a DC / DC converter, and various switching power supplies can be applied.

Further, the semiconductor switching element in the power conversion unit may be a voltage control type semiconductor switching element such as a junction type electric field effect transistor. The substrate material of the semiconductor switching element may be silicon or a wide-gap semiconductor such as silicon carbide.

Further, the element characteristics in the characteristic map information are not limited to the switching time, and may be other element characteristics such as switching loss (for example, turn-on loss).

6 Common control unit 10 Variable voltage source 11 Positive bias terminal 12 Negative bias terminal 13 Gate output terminal 14 Intermediate potential terminal 21 Input signal 22 Charging switch 23 Discharging switch 24 Charging resistance 25 Discharging resistance 31, 32 Characteristic map information 51 Characteristic map recording means 52 Interface circuit unit 54 Gate voltage tilt variable circuit unit 55 Gate voltage variable circuit unit 60 Gate voltage calculation means 67 Temperature sensor 68 Temperature detection unit 111,112 Power conversion unit 301, 302, 303, 304 Semiconductor switching element 305 , 306 Power module 400 Insulated transformer 401 Diode rectifier 402 Capacitor 403 Resistance 404 Constant voltage diode 430 Potential meter 431 Feedback terminal 432 Capacitor 433 Rectifier diode 434 Potential meter control terminal 501, 502, 503, 504 Drive circuit 511, 512 Characteristic map information acquisition means 516 DC / DC controller 517 Primary side negative power input terminal 518 Primary side positive power input terminal 551,552 Gate voltage target command 601 DC terminal (positive side)
602 DC terminal (negative electrode)
603 output terminal

Claims (10)

In the drive circuit of the power conversion unit provided in the power conversion unit that performs power conversion by the semiconductor switching element and drives the semiconductor switching element.
A voltage variable circuit unit that outputs a control drive voltage given to the semiconductor switching element is provided.
When a plurality of the power conversion units are connected in parallel and the semiconductor switching elements are connected in parallel, for each of the plurality of power conversion units,
It is given by a function in which the drive voltage is an independent variable and the turn-on time, which is the time from when the voltage of the control terminal of the semiconductor switching element starts to rise to when the current starts to flow in the semiconductor switching element, is used as the dependent variable. Based on the characteristic map information, the target command of the drive voltage corresponding to the target value of the turn-on time common to the plurality of power conversion units is calculated.
In the voltage variable circuit unit, the drive circuit of the power conversion unit is characterized in that the drive voltage is variably controlled so as to be the target command. In the drive circuit of the power conversion unit according to claim 1,
A drive circuit of a power conversion unit, which comprises a recording means for recording the characteristic map information. In the drive circuit of the power conversion unit according to claim 1,
The drive circuit of the power conversion unit, characterized in that the characteristic map information is registered in a database. In the drive circuit of the power conversion unit according to claim 1,
A drive circuit of a power conversion unit, wherein the semiconductor switching element is an IGBT, and the drive voltage is a gate power supply voltage. In the drive circuit of the power conversion unit according to claim 1,
The semiconductor switching element is a drive circuit of a power conversion unit, characterized in that it is included in either one of the upper and lower arms. In the drive circuit of the power conversion unit according to claim 1 or 5.
Further, the drive circuit of the power conversion unit is provided with a circuit unit that controls the resistance value of the gate resistance according to the drive voltage. In the drive circuit of the power conversion unit according to claim 1,
The characteristic map information includes information regarding the temperature dependence of the turn-on time.
The drive circuit of a power conversion unit, characterized in that the drive voltage is variably controlled so that the turn-on time becomes the target command based on the characteristic map information and the temperature detection value of the semiconductor switching element. In the driving method of a power conversion unit that performs power conversion by applying a driving voltage for control to a semiconductor switching element and driving the semiconductor switching element.
When a plurality of the power conversion units are connected in parallel and the semiconductor switching elements are connected in parallel, for each of the plurality of power conversion units,
It is given by a function in which the drive voltage is an independent variable and the turn-on time, which is the time from when the voltage of the control terminal of the semiconductor switching element starts to rise to when the current starts to flow in the semiconductor switching element, is used as the dependent variable. Based on the characteristic map information, the target command of the drive voltage corresponding to the target value of the turn-on time common to the plurality of power conversion units is calculated.
A method for driving a power conversion unit, which comprises setting a value of the driving voltage in the target command. Semiconductor switching elements and
The drive circuit that drives the semiconductor switching element and
With
In the power conversion unit that performs power conversion by the semiconductor switching element,
The drive circuit
A voltage variable circuit unit that outputs a control drive voltage given to the semiconductor switching element is provided.
When a plurality of the power conversion units are connected in parallel and the semiconductor switching elements are connected in parallel, for each of the plurality of power conversion units,
It is given by a function in which the drive voltage is an independent variable and the turn-on time, which is the time from when the voltage of the control terminal of the semiconductor switching element starts to rise to when the current starts to flow in the semiconductor switching element, is used as the dependent variable. Based on the characteristic map information, the target command of the drive voltage corresponding to the target value of the turn-on time common to the plurality of power conversion units is calculated.
A power conversion unit characterized in that in the voltage variable circuit unit, the drive voltage is variably controlled so as to be the target command. In a power conversion device configured by connecting a plurality of power conversion units including a semiconductor switching element and a drive circuit for driving the semiconductor switching element in parallel, and connecting the semiconductor switching elements in parallel.
A voltage variable circuit unit provided in each of the plurality of drive circuits and outputting a control drive voltage given to the semiconductor switching element, and a voltage variable circuit unit.
The time from when the voltage of the control terminal of the semiconductor switching element starts to rise to when the current starts to flow through the semiconductor switching element, with the drive voltage as an independent variable for each of the plurality of voltage variable circuit units. Based on the characteristic map information given by the function with the turn-on time as the dependent variable, the common control for creating the target command of the drive voltage corresponding to the target value of the turn-on time common to the plurality of power conversion units. Department and
With
In each of the plurality of voltage variable circuit units, the drive voltage is variably controlled so as to be the target command created by the common control unit for each of the plurality of voltage variable circuit units. Power conversion device.

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