JP4814908B2 - Power converter - Google Patents

Description

  The present invention relates to a power conversion device including a switching element that performs power conversion by switching.

  Conventionally, in a power conversion device including a switching element, at least one of physical quantities such as a time differential equivalent of a collector current, a time differential equivalent of a collector-emitter voltage, and a collector-emitter voltage equivalent at the time of switching of the switching element. A circuit for detecting the voltage is provided, and the gate-emitter voltage of the switching element is controlled according to the detected physical quantity value, or the power supply voltage or gate resistance of the gate circuit of the switching element is adjusted to reduce the noise. There is technology. (For example, refer to Patent Document 1).

Japanese Patent Application Laid-Open No. 10-150764

  Patent Document 1 discloses at least one of physical quantities such as a time differential equivalent of a collector current, a time differential equivalent of a collector-emitter voltage, and a collector-emitter voltage equivalent during switching of a switching element. A detection circuit is provided and the gate-emitter voltage of the switching element is controlled according to the value of the detected physical quantity, or the power supply voltage or gate resistance of the gate circuit of the switching element is adjusted. Therefore, there has been a problem that the apparatus becomes large and expensive.

  The present invention has been made to solve the above-described problems, and an object thereof is to provide a small and inexpensive power conversion device that does not require detection of a physical quantity at the time of switching.

The power conversion device according to the present invention is a power conversion device that drives an AC load by converting a DC power supply to an AC power supply, and includes a plurality of juxtapositions between a control board having a microcomputer that performs power conversion control and a cooler. Each power module includes a case, a plurality of switching elements that perform power conversion accommodated in the case, terminals of the switching element derived from the case, and affixed or stamped to the case A label or a mark indicating the solid characteristic information of the switching element, and the microcomputer of the control board stores the solid characteristic information of the switching element read from the label or mark. .

  The power conversion device according to the present invention is configured as described above, and the switching element driving circuit can be adjusted according to the individual characteristics of the switching elements, so that switching loss and radiation noise can be reduced. In addition, since the information obtained in the characteristic test performed in the finished product test of the power module is written in the microcomputer, it does not require a circuit for measuring the physical quantity of the switching element as in the past, and is small and inexpensive. A power converter can be constituted.

Embodiment 1 FIG.
Embodiment 1 of the present invention will be described below with reference to the drawings. FIG. 1 is a front view showing an external configuration of a power module according to Embodiment 1, and FIG. 2 is a diagram showing a circuit configuration of the power module. The same parts as those in FIG.

  As shown in FIG. 2, the circuit of the power module is the same as the switching element for the parallel connection body of the first IGBT (insulated gate bipolar transistor) 4a as the switching element and the first flywheel diode 5a. The parallel connection body of the second IGBT 4b and the second flywheel diode 5b is connected in series.

  P is the external DC terminal of the first IGBT 4a, N is the external DC terminal of the second IGBT 4b, AC is the AC terminal taken out from the connection point between the first IGBT 4a and the second IGBT 4b, and G1 is the first IGBT 4a. The gate terminal, G2 is the gate terminal of the second IGBT 4b, E1 is the emitter terminal of the first IGBT 4a, and E2 is the emitter terminal of the second IGBT 4b.

  For example, three power modules configured in this way are connected in parallel, and a direct current is applied between the P terminal and the N terminal of each power module, and is applied between G1-E1 and G2-E2 of each IGBT. It is used as a power conversion device such as an inverter for converting direct current into alternating current by taking out three-phase alternating current from each AC terminal of three power modules by controlling on / off of each switching element by voltage. Is. Specific examples of the inverter will be described later.

Further, 1 in FIG. 1 is a case that accommodates the above-described power module circuit, and 2 is a label that displays individual characteristic information of a switching element (IGBT) that constitutes the power module in a barcode, a two-dimensional code, a numerical value, and the like. Affixed or laser-marked on case 1. As the individual characteristic information, the on threshold voltage Vth of the power module, the switching loss E _ON at the time of turn-on, the switching loss E _OFF at the time of turn- _off , the gate-emitter capacitance C _{GE and the} like are shown in FIG. It is displayed in the form.

FIG. 4 is a configuration diagram of a power conversion device showing an example in which a three-phase PWM inverter is configured using three power modules shown in FIG. Each power module is juxtaposed on the cooler 6, and each DC terminal P, N is connected to the external DC terminal 8 via the bus bar 7, and the AC terminal AC of each power module is connected to each bus bar 9a, 9b, It is connected to external AC terminals U, V, W via 9c. Reference numerals 10a, 10b, and 10c are current sensors for measuring a three-phase current provided on the bus bars 9a, 9b, and 9c, respectively.

  FIG. 5 is a front view showing the control board 11 mounted on the apparatus of FIG. On the control board 11, an IC 12 for driving each switching element and a microcomputer 13 for performing power conversion control are mounted. The control board 11 is mounted after reading the individual characteristic information of the label 2 attached to each power module, and the read individual characteristic information is stored in the microcomputer 13.

  The individual characteristic displayed on the label 2 is information obtained in the characteristic test performed in the finished product test for each power module performed when the power module is completed.

  In the manufacture of power converters, the first non-defective test was performed when the power converter was completed. If the switching element is defective, the power module must be reassembled by disassembling all the boards and cases. However, since the number of salvage man-hours increases, it is common to first perform a non-defective product determination test with a single power module.

Normally, the non-defective product determination test for the power module alone measures the ON threshold voltage Vth, the switching loss E _ON at turn-on, the switching loss E _OFF at turn- _{off, and the} like.
The data is displayed on the label 2 in the form as shown in FIG. 3, and the contents are stored in the microcomputer 13, thereby reducing the size and cost of the circuit for measuring the physical quantity of the switching element compared to the conventional example. The power converter can be made.

Here, the relationship between the ON threshold voltage Vth when the switching element is turned on, the charging current to the gate of the switching element, the switching loss, and the radiation noise will be described. FIG. 6 is a diagram showing a path of a charging current when the switching element is turned on, and FIG. 7 is a diagram for explaining an operation when the switching element is turned on.

Since the mirror voltage in FIG. 7 is substantially equal to the ON threshold voltage Vth, the charging current to the gate of the switching element can be obtained by the following equation.

The relationship between the turn-on threshold voltage Vth and the charging current, switching loss, and radiation noise is as follows.
Large Vth → Small charging current, Large switching loss, Small radiation noise
Small Vth → Large charging current, Small switching loss, Large radiation noise

If the on-threshold voltage Vth is large, increase the positive bias voltage VG + of the gate power supply in equation (1), or reduce the resistance value of the gate-on resistance Rgon by laser trimming, etc. The charging current can be increased until the switching loss can be reduced.

On the other hand, when the ON threshold voltage Vth is small, the positive bias voltage VG + of the gate power supply in equation (1) is reduced, or the gate ON resistance Rgon is increased by laser trimming, etc. The charging current can be reduced to an allowable range of switching loss, and radiation noise can be reduced.

Next, the relationship between the ON threshold voltage Vth when the switching element is turned off, the discharge current from the gate of the switching element, the switching loss, and the radiation noise will be described. FIG. 8 is a diagram showing a path of a discharge current when the switching element is turned off, and FIG. 9 is a diagram for explaining an operation when the switching element is turned off.

Since the mirror voltage in FIG. 9 is substantially equal to the ON threshold voltage Vth, the discharge current from the gate of the switching element can be obtained by the following equation.

The relationship between the ON threshold voltage Vth and the discharge current, switching loss, and radiation noise at turn-off is as follows.
Large Vth → Large discharge current, Small switching loss, Large radiation noise
Small Vth → Small discharge current, Large switching loss, Small radiation noise

When the on-threshold voltage Vth is large, switching at turn-off by reducing the negative bias voltage VG− of the gate power supply in equation (2) or increasing the gate-off resistance Rgoff by laser trimming or the like. The discharge current can be reduced to the allowable range of loss, and radiation noise can be reduced.

On the other hand, when the on-threshold voltage Vth is small, radiation noise is generated by increasing the negative bias voltage VG− of the gate power supply in the equation (2) or by reducing the resistance value of the gate-off resistance Rgoff by laser trimming or the like. The discharge current can be increased up to the permissible range, and the switching loss at turn-off can be reduced.

  Next, a specific example of a method for adjusting the gate power supply voltage will be described. FIG. 10 is a circuit diagram for adjusting the gate power supply positive side voltage in the first embodiment. The microcomputer 13 storing the individual characteristic information from the IGBT label outputs a digital signal corresponding to the individual characteristic information to the D / A converter 14. By adjusting the output value from the D / A converter 14 according to the individual characteristic information stored in the microcomputer 13, the gate power source positive side voltage 15 can be adjusted. Reference numeral 16 denotes an insulating transformer.

It is a front view which shows the external appearance structure of the power module by Embodiment 1 of this invention. It is a figure which shows the circuit structure of a power module. 6 is a diagram illustrating an example of a label displaying individual characteristic information of a switching element according to Embodiment 1. FIG. It is a block diagram of the power converter device which shows the example which comprised the three-phase PWM inverter using the power module shown in FIG. It is a front view which shows the control board with which the apparatus of FIG. 4 was mounted | worn. It is a figure which shows the path | route of the charging current at the time of turn-on of a switching element. It is a figure for operation | movement explanation at the time of the turn-on of a switching element. It is a figure which shows the path | route of the discharge current at the time of turn-off of a switching element. It is a figure for operation | movement explanation at the time of turn-off of a switching element. FIG. 3 is a circuit diagram for adjusting a gate power supply positive side voltage in the first embodiment.

Explanation of symbols

1 Case, 2 Label, 4a, 4b 1st, 2nd IGBT, 5a, 5b 1st, 2nd flywheel diode, 6 Cooler, 7 Busbar, 8 External DC terminal,
9a, 9b, 9c bus bar, 10a, 10b, 10c current sensor, 11 control board,
12 switching element drive IC, 13 microcomputer, 14 D / A converter,
15 Gate power supply positive side voltage, 16 Insulated transformer.

Claims (4)

In a power converter for driving an AC load by converting a DC power source into an AC power source, the power module includes a plurality of power modules juxtaposed between a control board having a microcomputer for performing power conversion control and a cooler, and each of the power modules. Is a case, a plurality of switching elements that perform power conversion accommodated in the case, terminals of the switching element derived from the case, and solid state information of the switching element attached or engraved on the case A solid state information of the switching element read from the label or mark is stored in the microcomputer of the control board .   2. The power conversion device according to claim 1, wherein a drive circuit of the switching element is adjusted based on individual characteristic information of the switching element to reduce switching loss or radiation noise of the switching element.   The power conversion apparatus according to claim 1, wherein the individual characteristic information is at least one of an on threshold voltage, a switching loss, and a gate-emitter capacitance of the switching element.   3. The power conversion apparatus according to claim 2, wherein the adjustment of the drive circuit adjusts a gate power supply voltage applied to the switching element or a gate resistance connected to the gate circuit of the switching element.

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