JP4802499B2 - Power control circuit and vehicle - Google Patents

Description

  The present invention relates to a power control circuit and a vehicle, and more particularly to a power control circuit and a vehicle including a plurality of current control elements.

  Power control semiconductor elements such as IGBT (insulated gate bipolar transistor) elements are widely used. However, when a large current is switched, a surge voltage is often a problem.

  The surge voltage and switching loss of the IGBT element are in a trade-off relationship, and it is necessary to suppress the surge voltage and switching loss within an appropriate range by selecting an optimum resistance value.

  However, since the generation of surge voltage and switching loss in the semiconductor element differ depending on the operating state of the semiconductor power converter, changing the gate resistance of the semiconductor element according to the operating state of the apparatus can afford to suppress the surge voltage. When there is, there is sufficient suppression of switching loss, and when there is a margin in suppression of switching loss, surge voltage is sufficiently suppressed.

Japanese Patent Laid-Open No. 2002-198792 (Patent Document 1) discloses a semiconductor power conversion device in which a plurality of gate resistors are provided in parallel between a gate of an IGBT element and a gate driver circuit, and a resistance value is switched by a switch. .
JP 2002-198792 A (FIG. 4) JP 2002-199700 A

  In recent years, electric vehicles, hybrid vehicles, and fuel cell vehicles that drive wheels with motors have attracted attention. For example, an inverter for hybrid motor control is required to control a large current of several tens to several hundred amperes. Inverter devices that control motors for automobiles require a large current capacity, while further lightening and downsizing and cost reduction are required for further popularization in the future.

  As one of measures for increasing the current capacity and reducing the cost, there can be considered a method in which a number of general-purpose IGBT elements are connected in parallel according to the required current capacity.

  Technically, it is possible to manufacture a large-capacity single-element IGBT, but since the chip area per element increases, the manufacturing yield deteriorates and in this case the cost increases. Because there is.

  When the gate resistance value of the IGBT element is large, the time constant of the gate drive circuit becomes large, so that the switching speed of the element decreases. In this case, since the time required to turn on / off the current becomes long, the switching loss increases.

  Conversely, when the gate resistance value is small, the switching speed of the element increases. In this case, although the switching loss is reduced, the current on / off speed is increased, and the surge voltage due to the inductance component increases. That is, since there is a trade-off relationship between surge voltage and switching loss, it is not possible to reduce both at the same time. For example, if the gate resistance value is increased to reduce the surge voltage, the switching loss increases.

  Further, as disclosed in Japanese Patent Laid-Open No. 2002-198792 (Patent Document 1), when a switch circuit for switching the gate resistance to be used is provided, the gate resistance to be used is controlled by controlling the switch circuit according to the element usage situation. A control circuit for determination is also required. With the increase in the number of gate resistors, the switching circuit and the control circuit become complicated, which is disadvantageous in terms of space and cost.

  An object of the present invention is to provide a power control circuit and a vehicle with reduced surge voltage.

  In summary, the present invention is a power control circuit, which is connected in parallel between first and second nodes, each of which flows between the first and second nodes in response to a signal applied to a control electrode. And a plurality of resistance elements having different resistance values that are respectively connected between a common input node to which a control signal is applied and control electrodes of the plurality of current control elements.

  Preferably, each of the plurality of resistance elements has a resistance value determined in accordance with a cooling characteristic of the connected current control element.

  More preferably, the first current control element of the plurality of current control elements has better cooling characteristics than the second current control element of the plurality of current control elements. The first resistance element of the plurality of connected resistance elements has a larger resistance value than the second resistance element of the plurality of resistance elements connected to the second current control element.

  More preferably, the power control circuit further includes a substrate on which a plurality of current control elements and a plurality of resistance elements are mounted. The second current control element is disposed closer to the center of the substrate than the first current control element.

  More preferably, the power control circuit further includes a passage for flowing a cooling fluid for cooling, and a substrate disposed on the passage and on which the plurality of current control elements and the plurality of resistance elements are mounted. The second current control element is disposed downstream of the flow of the cooling fluid from the first current control element.

  According to another aspect of the present invention, the vehicle includes an inverter configured by any one of the power control circuits described above and a motor driven by the inverter.

  According to the present invention, by varying the input gate resistance values of the plurality of switching elements, the surge voltage can be suppressed without increasing the element heat generation, and the temperatures of the plurality of switching elements can be made uniform. it can.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. In the drawings, the same or corresponding parts are denoted by the same reference numerals, and description thereof will not be repeated.

  FIG. 1 is a circuit diagram for explaining a motor drive system portion of a vehicle in which the power control circuit of the present invention is used. Such a motor drive system is mounted on, for example, an electric vehicle, a hybrid vehicle, and a fuel cell vehicle.

  The vehicle shown in FIG. 1 includes a battery 4, a capacitor 6, an inverter device 2, and a motor 8.

  The battery 4 is a secondary battery such as nickel metal hydride or lithium ion. The capacitor 6 and the inverter device 2 are connected in parallel between the positive and negative electrodes of the battery 4. Capacitor 6 smoothes the surge component generated in inverter device 2.

  The inverter device 2 receives the power supply potential smoothed by the capacitor 6 and drives the AC motor 8. Further, the inverter device 2 returns the electric power generated in the AC motor 8 with regenerative braking to the battery 4.

  The AC motor 8 is a motor that generates torque for driving drive wheels (not shown) of the vehicle. For example, when this motor is mounted on a hybrid vehicle, it has the performance of a generator driven by an engine, and can operate as an electric motor for the engine and start the engine. Good.

  Inverter device 2 includes a U-phase arm UA, a V-phase arm VA, and a W-phase arm WA that are connected in parallel between terminals of a capacitor 6 to which a power supply voltage is applied. The inverter device 2 may be housed together with a control circuit (not shown) in one case as an intelligent power module (IPM).

  U-phase arm UA includes current control circuits 11 and 12 connected in series between terminals of capacitor 6, and diodes 21 and 22 connected in parallel with current control circuits 11 and 12, respectively. V-phase arm VA includes current control circuits 13 and 14 connected in series between terminals of capacitor 6, and diodes 23 and 24 connected in parallel with current control circuits 13 and 14, respectively. W-phase arm WA includes current control circuits 15 and 16 connected in series between terminals of capacitor 6, and diodes 25 and 26 connected in parallel with current control circuits 15 and 16, respectively.

  A connection node of the current control circuits 11 and 12 is connected to one end of a U-phase coil (not shown) of the motor 8. A connection node of the current control circuits 13 and 14 is connected to one end of a V-phase coil (not shown) of the motor 8. A connection node of the current control circuits 15 and 16 is connected to one end of a W-phase coil (not shown) of the motor 8. The other ends of the U-phase coil, V-phase coil, and W-phase coil are coupled together at the midpoint.

  FIG. 2 is a circuit diagram showing the configuration of the current control circuit 11 in FIG.

  Referring to FIG. 2, current control circuit 11 is connected in parallel between nodes N1 and N2, and each IGBT controls the current flowing between nodes N1 and N2 in accordance with a signal applied to the control electrode. Elements GA, GB, and GC, and resistance elements RA, RB, and RC, which are connected between a common input node to which a control signal is applied and control electrodes of IGBT elements GA, GB, and GC, and have different resistance values, respectively. Including. Here, the current flowing from the node N1 to N2 is IOUT, and the voltage between the nodes N1 and N2 is VOUT.

  Since current control circuits 11 to 16 in FIG. 1 have the same configuration as current control circuit 11 described in FIG. 2, description thereof will not be repeated.

  FIG. 3 is a diagram for explaining resistance values of resistance elements RA to RC in FIG.

  In FIG. 3, the gate resistance value means the resistance value of a resistor connected to the gate which is the control electrode of the IGBT element. The gate resistance value is larger, medium, and smaller in the order of the resistors RA, RB, RC when the resistors RA, RB, RC are compared.

  When the gate resistance value is large, switching of the IGBT element takes time and the switching loss is large. Therefore, the position where the IGBT element GA is mounted needs to be a position with good cooling efficiency. On the other hand, when the gate resistance value is small, the switching speed of the IGBT element is increased and the switching loss is reduced. Therefore, the cooling efficiency of the position where the IGBT element GC is mounted may be slightly worse than that of the IGBT element GA. The mounting position of the IGBT element GB is a mounting position with an intermediate cooling efficiency between the mounting positions of the IGBT element GA and the IGBT element GC.

  That is, each of resistors RA to RC has a resistance value determined in accordance with the cooling characteristics of IGBT elements GA to GC that are connected current control elements. The IGBT element GA has better cooling characteristics than the IGBT element GC, and the resistance RA connected to the IGBT element GA has a larger resistance value than the resistances RA to RC connected to the IGBT element GC.

  FIG. 4 is a diagram for explaining an example of the mounting position of the IGBT element.

  In FIG. 4, IGBT elements GA1, GB1, and GC1 and resistance elements RA1, RB1, and RC1 are element groups corresponding to the current control circuit 11 of FIG. On the other hand, IGBT elements GC2, GB2, GA2 and resistance elements RC2, RB2, RA2 are element groups corresponding to the current control circuit 12 of FIG.

  These IGBT elements are mounted on the heat radiation plate 40 of the IPM module. The cooling capacity of the central portion of the heat radiating plate 40 is worse than that of the peripheral portion. That is, if such a mounting position is used, the heat dissipation of the IGBT elements GC1 and GC2 is poor, whereas the heat dissipation of the IGBT elements GA1 and GA2 close to the periphery is improved. The resistance elements RC1 and RC2 connected to the respective control electrodes of the IGBT elements GC1 and GC2 at the mounting position have a small resistance value, and the control electrodes of the IGBT elements GA1 and GA2 are compared with this. The resistance values of the resistance elements RA1 and RA2 connected to are large.

  That is, the inverter device 2 that is a power control circuit corresponds to a substrate on which the IGBT elements GA1 to GC1 and GA2 to GC2 that are a plurality of current control elements and the RA1 to RC1 and RA2 to RC2 that are a plurality of resistance elements are mounted. A heat radiating plate 40 is provided. The IGBT elements GC1 and GC2 are disposed closer to the center of the heat dissipation plate 40 than the IGBT elements GA1 and GA2.

  With such an arrangement, the element temperature of the IGBT element can be kept uniform, and it is possible to prevent a specific element from jumping out and being destroyed at a high temperature.

  FIG. 5 is an operation waveform diagram for explaining an output waveform of the current limiting circuit of the present invention.

  2 and 5, waveforms W1 and W3 show current and voltage waveforms when resistors RA, RB, and RC are selected to have the same resistance value, and waveforms W2 and W4 are as shown in FIG. The current and voltage waveforms when the gate resistance value is selected are shown. The waveform W1 shows the case where the resistors RA and RB are set to the same value as the resistor RC of FIG.

  In the waveform W2, the rise at time t1 and the fall time at time t2 are large because the switching speeds of the IGBT elements GA and GB set the resistance values RA and RB large. However, since the overlapping of the switching periods of the IGBT elements GA, GB, and GC is shifted, the surge voltage is reduced from the waveform W3 to the waveform W4.

  FIG. 6 is a diagram for explaining a second example of the arrangement of the IGBT elements.

  Referring to FIG. 6, heat sink 54 and insulating substrate 56 are provided on passage 52 through which cooling water flows, and IGBT elements GA 3, GB 3, and GC 3 are mounted on insulating substrate 56. The cooling water absorbs the heat of the IGBT element, so that the temperature in the downstream is higher than that in the upstream. For this reason, the IGBT element GA3 disposed on the upstream side is well cooled, and the IGBT element GC3 disposed on the downstream side is poorly cooled. The IGBT element GB3 arranged between them is moderately cooled.

  Therefore, the IGBT element GA in FIG. 2 is mounted at the position of the IGBT element GA3 in FIG. 6, the IGBT element GB is mounted at the position GB3 in FIG. 6, and the IGBT element GC is mounted at the position GC3 in FIG. Thus, the relationship shown in FIG. 3 is established, and the surge voltage can be reduced.

  That is, the inverter device 2 that is a power control circuit includes a passage 52 through which a cooling fluid for cooling flows, and a substrate 56 that is disposed on the passage 52 and on which an IGBT element and a resistance element are mounted. And IGBT element GC3 is arrange | positioned in the downstream of the flow of a cooling water rather than IGBT element GA3.

  As described above, in the embodiment of the present invention, a plurality of switching elements are used by using different gate resistance values as resistance values connected to gates of switching elements such as a plurality of parallel-connected IGBT elements. The elements can be turned on / off sequentially. As a result, the overall current change rate (di / dt) at the time of switching becomes small, and the generation of surge voltage can be suppressed.

  For example, even when all the gate resistance values are increased, the surge voltage can be suppressed, but in this case, element heat generation due to switching loss increases. In this embodiment, the surge voltage can be suppressed without increasing the element heat generation by increasing only the gate resistance value of the element having relatively high cooling efficiency, and the temperature of the plurality of switching elements is also uniform. Can be

[Modification]
When switching elements such as a plurality of IGBT elements are connected in parallel, there may be a difference in loss characteristics due to variations occurring during manufacturing in the plurality of switching elements.

  Usually, it is necessary to use switching elements having a uniform loss characteristic as much as possible by managing element loss characteristics and excluding elements with large variations.

  However, such a strict selection increases the price of the switching element. Therefore, when there is variation in the loss of the switching element, the loss is measured in advance, and for the element having a relatively large loss, a small resistance is connected to the gate, and the gate voltage is driven by the resistance. On the other hand, the gate resistance value is increased for an element with relatively small loss. The gate resistor may be selected and mounted according to the loss characteristics of the switching element, but for example, a gate resistor whose resistance value can be changed by trimming after mounting on a printed wiring board may be used.

  By doing so, the surge voltage can be suppressed, and at the same time, the amount of heat generated by each element can be made uniform. Since it is possible to increase the allowable range of loss variation at the time of manufacturing the switching element, it is possible to use the variation product and to remove the restriction of the wafer lot.

  In this embodiment, the case where an IGBT element is used as an example of the switching element has been described. However, the switching element may be a MOS-FET, a bipolar transistor, a GTO, an inverse element thyristor, or the like instead of the IGBT element. good.

  The embodiment disclosed this time should be considered as illustrative in all points and not restrictive. The scope of the present invention is defined by the terms of the claims, rather than the description above, and is intended to include any modifications within the scope and meaning equivalent to the terms of the claims.

It is a circuit diagram for demonstrating the motor drive system part of the vehicle in which the power control circuit of this invention is used. FIG. 2 is a circuit diagram illustrating a configuration of a current control circuit 11 in FIG. 1. It is a figure for demonstrating the resistance value of resistance element RA-RC in FIG. It is a figure for demonstrating the example of the mounting position of an IGBT element. It is an operation | movement waveform diagram for demonstrating the output waveform of the current limiting circuit of this invention. It is a figure for demonstrating the 2nd example of arrangement | positioning of an IGBT element.

Explanation of symbols

  2 inverter device, 4 battery, 6 capacitor, 8 motor, 11-16 current control circuit, 21-26 diode, 40 heat dissipation plate, 52 passage, 54 heat sink, 56 insulating substrate, GA-GC, GA1-GC1, GA2-GC2 , GA3-GC3 IGBT elements, RA-RC, RA1-RC1, RC2-RA2 resistance elements, UA U-phase arm, VA V-phase arm, WA W-phase arm.

Claims (5)

A plurality of current control elements connected in parallel between the first and second nodes, each controlling a current flowing between the first and second nodes according to a signal applied to the control electrode;
A plurality of resistive elements connected between a common input node to which a control signal is applied and control electrodes of the plurality of current control elements, respectively, having different resistance values;
Each of the plurality of resistance elements has a resistance value determined in accordance with the cooling characteristics of the connected current control element ,
The power control circuit, wherein the plurality of current control elements are sequentially turned on / off at different switching speeds according to the resistance values of the corresponding resistance elements. The first current control element of the plurality of current control elements has better cooling characteristics than the second current control element of the plurality of current control elements,
The first resistance element of the plurality of resistance elements connected to the first current control element is a second resistance element of the plurality of resistance elements connected to the second current control element. greater resistance values compared to the power control circuit according to claim 1. Further comprising a substrate on which the plurality of current control elements and the plurality of resistance elements are mounted;
The power control circuit according to claim 2 , wherein the second current control element is disposed closer to a center portion of the substrate than the first current control element. A passage for flowing a cooling fluid for cooling;
A board disposed on the passage and on which the plurality of current control elements and the plurality of resistance elements are mounted;
The power control circuit according to claim 2 , wherein the second current control element is disposed downstream of the flow of the cooling fluid with respect to the first current control element. An inverter configured with the power control circuit according to any one of claims 1 to 4 ,
A vehicle comprising: a motor driven by the inverter.

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