Power conversion device, method for diagnosing deterioration of power conversion device, and deterioration computing device

Abstract

To enable accurate temperature estimation even if degradation of a switching element has proceeded.SOLUTION: A deterioration computing device comprises: a loss estimation unit 21; case temperature estimation units 24, 251; switching element chip temperature estimation units 22, 252; a conversion unit 26; a cumulative damage amount generation unit 27; and a heat impedance correction unit 29. The loss estimation unit 21 estimates a chip loss. The case temperature estimation units 24, 251 estimate a case temperature. The switching element chip temperature estimation units 22, 252 estimate a switching element chip temperature. The conversion unit 26 converts the case temperature into a heat cycle. The cumulative damage amount generation unit 27 generates a cumulative damage amount due to the heat cycle. The heat impedance correction unit 29 generates a first heat resistance change amount for correcting a case-fin heat impedance from the cumulative damage amount, and a second heat resistance change amount for correcting a switching element chip-case heat impedance.SELECTED DRAWING: Figure 4

Description

[Technical field]

[0001] The present invention relates to a power conversion device equipped with, for example, a switching element, a deterioration diagnosis method for a power conversion device, and a deterioration calculation device. [Background technology]

[0002] Power conversion devices, such as inverters and pulse width modulation (PWM) rectifiers, are configured using semiconductor elements such as MOSFETs (Metal Oxide Semiconductor Field Effect Transistors) and IGBTs (Insulated Gate Bipolar Transistors) as switching elements. These switching elements are used while being coupled to heat dissipation fins via heat dissipation grease such as silicone to prevent component failure due to heat generation. This allows heat generated from the switching elements to be released to the outside of the switching elements via the heat dissipation fins, thereby cooling the switching elements.

[0003] However, abnormalities may occur in the heat dissipation path between the switching element and the heat dissipation fin, such as a pumping-out phenomenon in which heat dissipation grease flows out from between the switching element and the heat dissipation fin due to a heat cycle caused by the operation and stop of the switching element. This abnormality causes the temperature of the heat dissipation fin to not rise relative to the temperature of the switching element, resulting in a rise in the surface temperature (junction temperature) of the switching element and causing thermal runaway in the semiconductor chip equipped with the switching element.

[0004] For this reason, there has been a strong demand for a technology to deal with the above abnormalities. Patent Document 1 describes a technology for calculating the power loss of a switching element from the rotation speed of a fan motor and the characteristics of the switching element, estimating the heat sink temperature from this power loss and a predetermined thermal impedance, and diagnosing an abnormality using the heat sink temperature. Patent Documents 2 and 3 describe a technology for calculating the power loss of a switching element from the operating conditions of an inverter and the characteristics of the switching element, and estimating the junction temperature of the switching element from this power loss and a predetermined thermal impedance. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] WO2020 / 208726 issue [Patent Document 2] JP 2019-158732 A [Patent Document 3] JP 2012-010490 A Summary of the Invention [Problem to be solved by the invention]

[0006] However, even with the techniques described in Patent Documents 1 to 3, the switching elements are repeatedly subjected to thermal cycles depending on the operating conditions of the inverter, which causes the pumping-out phenomenon of the heat dissipation grease and the deterioration of the base solder of the switching elements. As a result, the thermal impedance gradually increases from the initial stage of shipment, and the temperature estimation accuracy deteriorates.

[0007] An object of the present invention is to provide a power conversion device capable of highly accurate temperature estimation even when degradation of a switching element progresses, a degradation diagnosis method for a power conversion device, and a degradation calculation device. [Means for solving the problem]

[0008] In order to achieve the above object, a power conversion device according to one aspect of the present invention includes a switching circuit having a switching element chip accommodated in a case and fins for cooling the switching element chip, a temperature sensor for detecting the temperature of the fins, a control unit for controlling the on / off of the switching element chip, a loss estimation unit for estimating chip loss of the switching element chip based on control information used for controlling the on / off of the switching element chip, a case temperature estimation unit for estimating a case temperature based on the chip loss of the switching element chip, a stored case-to-fin thermal impedance, and the temperature of the fin detected by the temperature sensor, and an estimation unit for estimating the temperature of the switching element chip based on the case temperature, the chip loss of the switching element chip, and the stored switching element chip-to-case thermal impedance. the case temperature estimation unit; a first conversion unit that converts the case temperature into a first thermal cycle; a first cumulative damage amount generation unit that obtains first life data for the first thermal cycle and generates a first cumulative damage amount due to the first thermal cycle based on the first thermal cycle and the first life data; and a first thermal impedance correction unit that generates a first thermal resistance change amount for correcting the case-fin thermal impedance and a second thermal resistance change amount for correcting the switching element chip-case thermal impedance based on the first cumulative damage amount, corrects the case-fin thermal impedance stored in the case temperature estimation unit based on the first thermal resistance change amount, and corrects the switching element chip-case thermal impedance stored in the switching element chip temperature estimation unit based on the second thermal resistance change amount.

[0009] Further, a deterioration diagnosis method for a power conversion device according to one aspect of the present invention is a deterioration diagnosis method for a power conversion device including a switching circuit having a switching element chip accommodated in a case and fins for cooling the switching element chip, a temperature sensor for detecting the temperature of the fins, and a control unit for controlling the on / off of the switching element chip, the deterioration diagnosis method including the steps of: estimating chip loss of the switching element chip based on control information used for controlling the on / off of the switching element chip; estimating a case temperature based on the chip loss of the switching element chip, a stored case-fin thermal impedance, and the temperature of the fin detected by the temperature sensor; and the step of estimating a temperature of the switching element chip based on a switching element chip-to-case thermal impedance obtained by converting the case temperature into a thermal cycle; obtaining life data for the thermal cycle and generating an amount of accumulated damage due to the thermal cycle based on the thermal cycle and the life data; generating a first amount of thermal resistance change for correcting the case-to-fin thermal impedance and a second amount of thermal resistance change for correcting the switching element chip-to-case thermal impedance based on the amount of accumulated damage, correcting the case-to-fin thermal impedance based on the first amount of thermal resistance change, and correcting the switching element chip-to-case thermal impedance based on the second amount of thermal resistance change.

[0010] Furthermore, a deterioration calculation device according to one aspect of the present invention includes a loss estimation unit that estimates chip loss of the switching element chip based on control information output from a power conversion device including a switching circuit having a switching element chip accommodated in a case and fins for cooling the switching element chip and used to control on / off of the switching element chip, a case temperature estimation unit that estimates a case temperature based on the chip loss of the switching element chip, a stored case-fin thermal impedance, and a temperature of the fin output from the power conversion device, and a switching element chip estimation unit that estimates the temperature of the switching element chip based on the case temperature, the chip loss of the switching element chip, and the stored switching element chip-case thermal impedance. the case temperature estimation unit; a conversion unit that converts the case temperature into a thermal cycle; a cumulative damage amount generation unit that obtains life data for the thermal cycle and generates a cumulative damage amount due to the thermal cycle based on the thermal cycle and the life data; and a thermal impedance correction unit that generates a first thermal resistance change amount for correcting the case-fin thermal impedance and a second thermal resistance change amount for correcting the switching element chip-case thermal impedance based on the cumulative damage amount, corrects the case-fin thermal impedance stored in the case temperature estimation unit based on the first thermal resistance change amount, and corrects the switching element chip-case thermal impedance stored in the switching element chip temperature estimation unit based on the second thermal resistance change amount. Effect of the Invention

[0011] According to one aspect of the present invention, even if the switching element is deteriorated, a highly accurate temperature estimation can be performed. [Brief description of the drawings]

[0012] [Figure 1] 1 is a block diagram showing a schematic configuration of a power conversion device according to a first embodiment. [Diagram 2] 2 is a cross-sectional view showing an example of a mounting structure of the inverter main circuit shown in FIG. 1. [Diagram 3] This is a thermal equivalent circuit corresponding to the mounting structure of the inverter main circuit shown in Figure 2. [Figure 4] FIG. 2 is a block diagram for explaining the function of a computing unit according to the first embodiment. [Diagram 5] 13 is a thermal equivalent circuit corresponding to a mounting structure of an inverter main circuit according to a second embodiment. [Figure 6] FIG. 11 is a block diagram for explaining the function of a computing unit according to a second embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0013] Each embodiment of the present invention is an example of an apparatus or method for embodying the technical idea of ​​the present invention, and the technical idea of ​​the present invention does not specify the material, shape, structure, arrangement, etc. of the components to those described below. The technical idea of ​​the present invention can be modified in various ways within the technical scope defined by the claims.

[0014] <First embodiment> 1 is a block diagram showing a schematic configuration of a power conversion device according to embodiment 1. The power conversion device 1 includes an inverter main circuit 11 as a switching circuit, a motor 12 that is powered and driven by the inverter main circuit 11, an input voltage detector 13, an output voltage detector 14, an output current detector 15, and a controller 16.

[0015] The inverter main circuit 11 has an IGBT (Insulated Gate Bipolar Transistor) element chip 111 as a switching element chip, and an FWD (Free Wheeling Diode) chip 112 connected in anti-parallel to the IGBT element chip 111. The inverter main circuit 11 converts an input voltage into an output voltage required to drive the motor 12 by the switching operation of the IGBT element chip 111. The FWD chip 112 protects the IGBT element chip 111 by commutating the load current from the motor 12. The IGBT element chip 111 is bridge-connected to other IGBT element chips to form one arm.

[0016] The input voltage detector 13 detects the input voltage of the inverter main circuit 11. The output voltage detector 14 detects the output voltage of the inverter main circuit 11. The output current detector 15 detects the output current of the inverter main circuit 11. The controller 16 controls the on / off of the IGBT element chip 111 by PWM control based on the detection result by the input voltage detector 13, the detection result by the output voltage detector 14, and the detection result by the output current detector 15. The controller 16 may also control the on / off of the IGBT element chip 111 by PFM control.

[0017] The controller 16 is connected to the calculator 2, which serves as a deterioration calculation device, via a communication line NW1, and is connected to the user interface 3 via a communication line NW2. The controller 16 generates control information used for the PWM control from a control command input from the user interface 3, and transmits the control information used for the PWM control to the user interface 3 as operating condition information. The user interface 3 is connected to the calculator 2 via a communication line NW3. The user interface 3 transmits control information set by the user to the controller 16, and transmits operating condition information generated by the controller 16 based on the control information to the calculator 2. The calculator 2 is connected to a fin temperature sensor 18, not shown, which will be described later, and converts the fin temperature T finFrom the operating condition information, the temperatures of the IGBT chip 111 and the FWD chip 112 are estimated. Note that wired or wireless communication lines NW1 to NW3 are used.

[0018] (Mounting structure of inverter main circuit 11) 2 is a cross-sectional view showing an example of a mounting structure of an inverter main circuit 11 that is a target of degradation diagnosis. The inverter main circuit 11 includes a wire bond part wb, an IGBT element chip 111, an FWD chip 112, an IGBT element chip lower solder layer m1, a first copper layer m2, a ceramic layer m3, a second copper layer m4, a base solder layer m5, a base plate m6, an FWD chip lower solder layer m9, a terminal lower solder layer m10, a third copper layer m11, a case m12, and a terminal 113. The wire bond part wb is joined by solder to the surface of the IGBT element chip 111, the surface of the FWD chip 112, and the surface of the third copper layer m11. The first copper layer m2, the ceramic layer m3, the second copper layer m4, and the third copper layer m11 constitute an insulating substrate DBC. The IGBT element chip 111 and the FWD chip 112 are housed in a case m12.

[0019] The IGBT element chip 111 and the first copper layer m2 are joined by an IGBT element chip lower solder layer m1. The FWD chip 112 and the first copper layer m2 are joined by an FWD chip lower solder layer m9. The terminal 113 and the third copper layer m11 are joined by a terminal lower solder layer m10. The second copper layer m4 and the base plate m6 are joined by a base solder layer m5. The fins 17 are in contact with the underside of the base plate m6 (the heat dissipation surface hf side) via the terminals 113. The fins 17 cool the inverter main circuit 11. A fin temperature sensor 18 is connected to the fins 17. The fin temperature sensor 18 detects the temperature of the fins 17.

[0020] The heat of the IGBT element chip 111 passes through a heat dissipation path formed across the IGBT element chip lower solder layer m1, the first copper layer m2, the ceramic layer m3, the second copper layer m4, the base solder layer m5, and the base plate m6, and is dissipated from the heat dissipation surface hf of the base plate m6 to the outside of the inverter main circuit 11. The heat of the FWD chip 112 passes through a heat dissipation path formed across the FWD chip lower solder layer m9, the first copper layer m2, the ceramic layer m3, the second copper layer m4, the base solder layer m5, and the base plate m6, and is dissipated from the heat dissipation surface hf of the base plate m6 to the outside of the inverter main circuit 11.

[0021] The cooling temperature by the fin 17 is transferred through a heat dissipation path formed through the terminal 113, the terminal solder layer m10, the third copper layer m11, the ceramic layer m3, the second copper layer m4, the base solder layer m5, and the base plate m6. case is the temperature of the heat dissipation surface hf of the base plate m6. igbt is the temperature of the IGBT element chip 111. FWD chip temperature T fwd is the temperature of the FWD chip 112.

[0022] (Thermal equivalent circuit of inverter main circuit 11) FIG. 3 is a thermal equivalent circuit corresponding to the mounting structure of the inverter main circuit 11 in FIG. igbt corresponds to the heat source included in the IGBT element chip 111. igbt chip and heat capacity C igbt chip correspond to the thermal resistance component and the thermal capacity component of the IGBT element chip 111, respectively. igbt solder1 and heat capacity C igbt solder1 correspond to the thermal resistance component and the thermal capacity component of the solder layer m1 under the IGBT chip, respectively.

[0023] Thermal resistance R igbt copper1 and heat capacity C igbt copper1 correspond to the thermal resistance and heat capacity components of the first copper layer m2, respectively. igbt ceramic and heat capacity C igbt ceramiccorrespond to the thermal resistance and heat capacity components of the ceramic layer m3, respectively. igbt copper2 and heat capacity C igbt copper2 correspond to the thermal resistance and heat capacity components of the second copper layer m4, respectively. igbt solder2 and heat capacity C igbt solder2 correspond to the thermal resistance component and the heat capacity component of the base solder layer m5, respectively. igbt solder2 is the thermal resistance R of the base solder layer m5 near the IGBT element chip 111 igbt solder2 It corresponds to the change in thermal resistance R igbt baseplate and heat capacity C igbt baseplate correspond to the thermal resistance component and the thermal capacity component of the base plate m6, respectively.

[0024] Thermal resistance R igbt chip ~Thermal resistance R igbt baseplate , heat capacity C igbt chip ~heat capacity C igbt baseplate is the IGBT chip-case thermal impedance Z th(igbt-case) Configure.

[0025] On the other hand, the loss Pfwd corresponds to the heat source included in the FWD chip 112. fwd chip and heat capacity C fwd chip correspond to the thermal resistance component and the thermal capacity component of the FWD chip 112, respectively. fwd solder1 and heat capacity C fwd solder1 correspond to the thermal resistance component and the thermal capacity component, respectively, of the solder layer m9 under the FWD chip.

[0026] Thermal resistance R fwd copper1 and heat capacity C fwd copper1 correspond to the thermal resistance and heat capacity components of the first copper layer m2, respectively. fwd ceramic and heat capacity C fwd ceramic correspond to the thermal resistance and heat capacity components of the ceramic layer m3, respectively. fwd copper2 and heat capacity C fwd copper2 correspond to the thermal resistance and heat capacity components of the second copper layer m4, respectively. fwd solder2 and heat capacity C fwd solder2correspond to the thermal resistance component and the heat capacity component of the base solder layer m5, respectively. fwd solder2 is the thermal resistance R of the base solder layer m5 near the FWD chip 112 fwd solder2 It corresponds to the change in thermal resistance R fwd baseplate and heat capacity C fwd baseplate correspond to the thermal resistance component and the thermal capacity component of the base plate m6, respectively.

[0027] Thermal resistance R fwd chip ~Thermal resistance R fwd baseplate , heat capacity C fwd chip ~heat capacity C fwd baseplate is the thermal impedance between the FWD chip and case, Z th(fwd-case) Configure.

[0028] In addition, the thermal resistance R fin and heat capacity C fin correspond to the thermal resistance component and the thermal capacity component of the fin 17, respectively. tim and heat capacity C igbt tim corresponds to the thermal resistance component and the heat capacity component of the terminal 113, the terminal solder layer m10, and the third copper layer m11, respectively. tim is the thermal resistance R of the terminal 113, the terminal solder layer m10, and the third copper layer m11. tim It corresponds to the change in thermal resistance R fin ~Thermal resistance R tim and heat capacity C fin ~heat capacity C igbt tim is the case-to-fin thermal impedance Z th(case-fin) Configure.

[0029] As shown in Figure 3, the thermal impedance between the IGBT chip and the case, Z th(igbt-case) Thermal resistance R igbt chip ~Thermal resistance R igbt baseplate is the case-to-fin thermal impedance Z th(case-fin) It is connected in series between the heat capacity C igbt chip is the thermal resistance R igbt chip and the reference temperature point. igbt solder1 is the thermal resistance R igbt solder1 and the reference temperature point. igbt copper1is the thermal resistance R igbt copper1 and the reference temperature point. igbt ceramic is the thermal resistance R igbt ceramic and the reference temperature point. igbt copper2 is the thermal resistance R igbt copper2 and the reference temperature point. igbt solder2 is the thermal resistance R igbt solder2 and the reference temperature point. igbt baseplate is the thermal resistance R igbt baseplate and a reference temperature point.

[0030] FWD chip-case thermal impedance Z th(fwd-case) Thermal resistance R fwd chip ~Thermal resistance R fwd baseplate is the IGBT chip-case thermal impedance Z th(igbt-case) It is connected in parallel to the case-to-fin thermal impedance Z th(case-fin) It is connected in series between the heat capacity C fwd chip is the thermal resistance R fwd chip and the reference temperature point. fwd solder1 is the thermal resistance R fwd solder1 and the reference temperature point. fwd copper1 is the thermal resistance R fwd copper1 and the reference temperature point. fwd ceramic is the thermal resistance R fwd ceramic and the reference temperature point. fwd copper2 is the thermal resistance R fwd copper2 and the reference temperature point. fwd solder2 is the thermal resistance R fwd solder2 and the reference temperature point. fwd baseplate is the thermal resistance R fwd baseplate and a reference temperature point.

[0031] Case-to-fin thermal impedance Z th(case-fin) Thermal resistance R fin and thermal resistance R tim is the fin temperature T fin and the IGBT chip-case thermal impedance Z th(igbt-case)and FWD chip-case thermal impedance Z th(fwd-case) It is connected in series between the heat capacity C fin is the thermal resistance R fin and the reference temperature point. igbt tim is the thermal resistance R tim and a reference temperature point.

[0032] 4 is a block diagram for explaining the function of the calculator 2 according to the first embodiment. As shown in FIG. 4, the calculator 2 includes an IGBT element loss estimator 21, an IGBT chip-case temperature estimator 22, an FWD chip-case temperature estimator 23, a case-fin temperature estimator 24, a temperature calculator 25, a thermal cycle converter 26 as a first converter, an accumulated damage generator 27 as a first accumulated damage generator, and a ΔT c The power cycle life data storage unit 28 and an accumulated damage amount / ΔR conversion unit 29 serving as a first thermal impedance correction unit are provided. The case-fin temperature estimation unit 24 and the adder 251 of the temperature calculation unit 25 constitute a case temperature estimation unit. The IGBT chip-case temperature estimation unit 22 and the adder 252 of the temperature calculation unit 25 constitute a switching element chip temperature estimation unit. The FWD chip-case temperature estimation unit 23 and the adder 253 of the temperature calculation unit 25 constitute a diode chip temperature estimation unit.

[0033] FIG. 4 shows an example of the IGBT chip temperature T igbt and FWD chip temperature T fwd This is the temperature estimation block.

[0034] The IGBT element loss estimation unit 21 receives operating condition information including the input voltage, modulation method, switching frequency, and output voltage / current command value output from the controller 16, and the IGBT chip temperature T igbt and FWD chip temperature T fwdThe IGBT element loss estimation unit 21 estimates the input operating condition information (DC voltage, modulation method, switching frequency, output voltage / current command value) and the IGBT chip temperature T igbt and FWD chip temperature T fwd In response to the above, the static characteristics (on-state voltage) and dynamic characteristics (switching loss) of the IGBT element chip 111 that are stored in advance are read, and the loss P igbt and the loss P generated by the FWD chip 112 fwd Calculate.

[0035] The IGBT chip-case temperature estimation unit 22 estimates the loss P igbt and the pre-stored IGBT chip-case thermal impedance Z th(igbt-case) From this, the IGBT chip-case temperature T igbt-case The IGBT chip-case temperature estimation unit 22 calculates the input thermal resistance change amount ΔR igbt solder2 Based on the IGBT chip-to-case thermal impedance Z th(igbt-case) is corrected.

[0036] The FWD chip-case temperature estimation unit 23 estimates the loss P fwd and the pre-stored FWD chip-case thermal impedance Z th(fwd-case) From this, the FWD chip-case temperature T fwd-case The FWD chip-case temperature estimator 23 calculates the input thermal resistance change amount ΔR fwd solder2 Based on the FWD chip-to-case thermal impedance Z th(fwd-case) is corrected.

[0037] The case-fin temperature estimation unit 24 estimates the loss P igbt and loss P fwd and the case-to-fin thermal impedance Z th(case-fin) From this, the case-fin temperature T case-fin The case-fin temperature estimation unit 24 calculates the input thermal resistance change amount ΔR timBased on the case-to-fin thermal impedance Z th(case-fin) is corrected.

[0038] The temperature calculation unit 25 includes adders 251, 252, and 253. The adder 251 receives the case-fin temperature T case-fin and the fin temperature T detected by the fin temperature sensor 18 fin The adder 251 then calculates the case-to-fin temperature T case-fin and the fin temperature T fin By adding these, the case temperature T case Request.

[0039] The adder 252 receives the IGBT chip-case temperature T igbt-case and the case temperature T calculated by adder 251. case The adder 252 then calculates the IGBT chip-case temperature T igbt-case and case temperature T case By adding these, the IGBT chip temperature T igbt Request.

[0040] The adder 253 receives the FWD chip-case temperature T fwd-case and the case temperature T calculated by adder 251. case The adder 253 then calculates the FWD chip-case temperature T fwd-case and case temperature T case By adding these, the FWD chip temperature T fwd The IGBT chip temperature T igbt and FWD chip temperature T fwd is output to the IGBT element loss estimation unit 21 and also to the user interface 3 via the communication line NW3. igbt and FWD chip temperature T fwdBy observing this, it is possible to perform a deterioration diagnosis of the power conversion device 1, and it is possible to take measures such as protecting the power conversion device 1 from overheating and to estimate its lifespan.

[0041] Case temperature T case is output to the thermal cycle conversion unit 26. The thermal cycle conversion unit 26 converts the input case temperature T case By applying the counting method, the complex temperature change is decomposed into a combination of simple thermal cycles. Various counting methods have been proposed, for example, the rainflow method can be used. The thermal cycle data is output to the cumulative damage amount generating unit 27.

[0042] The cumulative damage amount generating unit 27 includes ΔT c The power cycle life data storage unit 28 is connected. ΔT c The power cycle life data storage unit 28 stores various T c Power cycle life count data corresponding to the cycle (ΔT c Power cycle life data) is stored. ΔT c For the power cycle life data, for example, the data sheet provided by the switch element manufacturer can be used. In addition to the measurement, various T c A cycle may be defined.

[0043] The cumulative damage amount generating unit 27 calculates the number of power cycles corresponding to each thermal cycle as ΔT c The amount of damage for each thermal cycle is calculated and accumulated by referring to the power cycle life data storage unit 28 and using the cumulative fatigue damage rule. For example, when a linear fatigue damage rule is used, the number of cycles under a certain temperature condition decomposed by the thermal cycle conversion unit 26 is N, ΔT c The number of power cycles under the same temperature conditions stored in the power cycle life data storage unit 28 is N f Then, the cumulative damage amount D at a certain point in time is calculated as follows:

number

[0044] The accumulated damage amount D calculated by the accumulated damage amount generating unit 27 is output to an accumulated damage amount / ΔR converting unit 29. The accumulated damage amount / ΔR converting unit 29 is provided with a data storage unit 291. The data storage unit 291 stores the thermal resistance change amount ΔR of the base solder layer m5 near the IGBT element chip 111, which corresponds to the accumulated damage amount D calculated in advance by measurement or analysis. igbt solder2 , the thermal resistance change amount ΔR of the base solder layer m5 near the FWD chip 112 fwd solder2 , the thermal resistance change amount ΔR of the TIM (Terminal Interface Material) including the terminal 113, the terminal solder layer m10, and the third copper layer m11 tim The value is stored.

[0045] The cumulative damage amount / ΔR conversion unit 29 refers to the data storage unit 291 to calculate the thermal resistance change amount ΔR corresponding to the cumulative damage amount D output from the cumulative damage amount generation unit 27. igbt solder2 , ΔR fwd solder2 , ΔR tim Then, the cumulative damage amount / ΔR conversion unit 29 calculates the thermal resistance change amount ΔR igbt solder2 to the IGBT chip-case temperature estimating unit 22, and the IGBT chip-case thermal impedance Z th(igbt-case) The cumulative damage amount / ΔR conversion unit 29 corrects the thermal resistance change amount ΔR fwd solder2 to the FWD chip-case temperature estimating unit 23, and the FWD chip-case thermal impedance Z th(fwd-case) Furthermore, the cumulative damage amount / ΔR conversion unit 29 corrects the thermal resistance change amount ΔR tim to the case-fin temperature estimating unit 24, and the case-fin thermal impedance Z th(case-fin) Correct the following.

[0046] <Effects of the First Embodiment> As described above, according to the first embodiment, the case temperature T caseDepending on the degree of power cycle deterioration corresponding to ΔTc, the IGBT chip-case thermal impedance Z th(igbt-case) , FWD chip-case thermal impedance Z th(fwd-case) , case-to-fin thermal impedance Z th(case-fin) By correcting the case temperature T case ΔT corresponding to c High-precision IGBT chip temperature T taking into account temperature rise due to power cycle degradation igbt and fwd chip temperature T fwd This makes it possible to estimate the IGBT chip temperature T igbt and fwd chip temperature T fwd to the user interface 3 via the communication line NW3, the administrator of the power conversion device 1 can c IGBT chip temperature T due to temperature rise caused by power cycle deterioration igbt and FWD chip temperature T fwd By looking at this, it is possible to perform overheat protection and life estimation for the power conversion device 1. Examples of overheat protection include (1) correction of the threshold value for fin temperature abnormality, (2) operation restrictions for restricting the temperature rise of the IGBT chip 111 and the FWD chip 112 of the controller 16 (limitation of output current and limiting carrier frequency), and (3) improvement of cooling capacity (increasing the rotation speed of the cooling fan and increasing the flow rate of the cooling water).

[0047] According to the first embodiment, the previously measured ΔT c ΔT corresponding to power cycle c Power cycle life data ΔT c By storing the data in the power cycle life data storage unit 28, ΔT c Using the ΔTc power cycle life data stored in the power cycle life data storage unit 28, each ΔT c The cumulative damage D of the power cycle can be calculated.

[0048] According to the first embodiment, the thermal resistance change amount ΔR corresponding to the cumulative damage amount D measured in advance is igbt solder2, ΔR fwd solder2 , ΔR tim The value of the cumulative damage amount / ΔR conversion unit 29 is stored in the data storage unit 291 of the cumulative damage amount / ΔR conversion unit 29, and the thermal resistance change amount ΔR of the base solder layer m5 near the IGBT element chip 111 stored in the data storage unit 291 is igbt solder2 , the thermal resistance change amount ΔR of the base solder layer m5 near the FWD chip 112 fwd solder2 , the change in thermal resistance of the TIM ΔR tim Using the data, a simple procedure can be used to determine the appropriate IGBT chip-to-case thermal impedance Z th(igbt-case) , FWD chip-case thermal impedance Z th(fwd-case) , case-to-fin thermal impedance Z th(case-fin) Correction can be made.

[0049] In the first embodiment, an example has been described in which the calculator 2 is connected to the controller 16 of the power conversion device 1 via the communication line NW1, but the calculator 2 may be directly connected to the controller 16. In this case, the control information may be input directly from the controller 16 to the calculator 2.

[0050] Furthermore, in the first embodiment, an example has been described in which the output of fin temperature sensor 18 is directly input to calculator 2, but the output of fin temperature sensor 18 may be input to controller 16. In this case, the operating condition information generated by controller 16 may include the value of fin temperature sensor 18.

[0051] Furthermore, the IGBT element loss estimation unit 21, the IGBT chip-to-case temperature estimation unit 22, the FWD chip-to-case temperature estimation unit 23, the case-to-fin temperature estimation unit 24, the temperature calculation unit 25, the thermal cycle conversion unit 26, the accumulated damage amount generation unit 27, and the accumulated damage amount / ΔR conversion unit 29 of the first embodiment may be realized by software using a CPU.

[0052] <Second embodiment> The second embodiment of the present invention is j Power Cycle (ΔT igbt ,ΔT fwd) causes the solder under the chip to deteriorate, which is another cause of temperature rise. igbt ,ΔT fwd Thermal resistance increase due to power cycling ΔZ th(igbt-case) , ΔZ th(fwd-case) A calculation block has been added to calculate

[0053] Fig. 5 is a thermal equivalent circuit corresponding to the mounting structure of the inverter main circuit 11 according to the second embodiment. In Fig. 5, the same parts as those in Fig. 3 are given the same reference numerals and detailed description thereof will be omitted.

[0054] IGBT chip-case thermal impedance Z th(igbt-case) In this case, the thermal resistance change ΔR igbt solder1 is the thermal resistance R of the solder layer m1 under the IGBT chip igbt solder1 Also, the change in the thermal impedance between the FWD chip and the case Z th(fwd-case) In this case, the change in thermal resistance ΔR fwd solder1 is the thermal resistance R of the solder layer m9 under the FWD chip fwd solder1 corresponds to the change in

[0055] Fig. 6 is a block diagram for explaining the function of a calculator 2A according to the second embodiment. In Fig. 6, the same parts as those in Fig. 4 are given the same reference numerals and detailed explanations are omitted.

[0056] The calculator 2A calculates ΔR th(igbt-case) The correction block includes a thermal cycle conversion unit 31 as a second conversion unit, a cumulative damage amount generation unit 32 as a second cumulative damage amount generation unit, and a ΔT igbt The device includes a power cycle life data storage unit 33 and an accumulated damage amount / ΔR conversion unit 34 serving as a second thermal impedance correction unit.

[0057] In addition, the calculator 2A calculates ΔR th(fwd-case) The correction block includes a heat cycle conversion unit 41 as a third conversion unit, a cumulative damage amount generation unit 42 as a third cumulative damage amount generation unit, and a ΔT fwdThe system includes a power cycle life data storage unit 43 and an accumulated damage amount / ΔR conversion unit 44 serving as a third thermal impedance correction unit.

[0058] The IGBT chip-case temperature estimation unit 22 estimates the input thermal resistance change amount ΔR igbt solder1 Based on the IGBT chip-to-case thermal impedance Z th(igbt-case) The FWD chip-case temperature estimator 23 corrects the input thermal resistance change amount ΔR fwd solder1 Based on the FWD chip-to-case thermal impedance Z th(fwd-case) is corrected.

[0059] ΔR th(igbt-case) In the correction block, the thermal cycle conversion unit 31 receives the IGBT chip temperature T igbt The thermal cycle conversion unit 31 converts the input IGBT chip temperature T igbt By applying the counting method, the complex temperature change is decomposed into a combination of simple thermal cycles. The thermal cycle data is output to the cumulative damage amount generating unit 32.

[0060] The cumulative damage amount generating unit 32 includes ΔT igbt The power cycle life data storage unit 33 is connected. ΔT igbt The power cycle life data storage unit 33 stores various T igbt Power cycle life count data corresponding to the cycle (ΔT igbt Power cycle life data) is stored. ΔT igbt The power cycle life data can be obtained from, for example, a data sheet provided by a switch element manufacturer.

[0061] The cumulative damage amount generating unit 32 calculates the number of power cycles corresponding to each thermal cycle as ΔT igbt The power cycle life data storage unit 33 is referenced, and the damage amount for each thermal cycle is calculated using the cumulative fatigue damage rule, and is cumulatively added.

[0062] The data of the amount of accumulated damage calculated by the accumulated damage amount generating unit 32 is output to an accumulated damage amount / ΔR converting unit 34. The accumulated damage amount / ΔR converting unit 34 is provided with a data storage unit 341. The data storage unit 341 stores the amount of change in thermal resistance ΔR of the solder layer m1 under the IGBT element chip, which corresponds to the amount of accumulated damage calculated in advance by measurement or analysis. igbt solder1 The value is stored.

[0063] The cumulative damage amount / ΔR conversion unit 34 refers to the data storage unit 341 to calculate the thermal resistance change amount ΔR corresponding to the cumulative damage amount output from the cumulative damage amount generation unit 32. igbt solder1 Then, the cumulative damage amount / ΔR conversion unit 34 calculates the thermal resistance change amount ΔR igbt solder1 to the IGBT chip-case temperature estimating unit 22, and the IGBT chip-case thermal impedance Z th(igbt-case) Correct the following.

[0064] ΔR th(fwd-case) In the correction block, the thermal cycle conversion unit 41 receives the FWD chip temperature T fwd The thermal cycle conversion unit 41 converts the input FWD chip temperature T fwd By applying the counting method, the complex temperature change is decomposed into a combination of simple thermal cycles. The thermal cycle data is output to the cumulative damage amount generating unit 42.

[0065] The cumulative damage amount generating unit 42 includes ΔT fwd The power cycle life data storage unit 33 is connected. ΔT fwd The power cycle life data storage unit 43 stores various T fwd Power cycle life count data corresponding to the cycle (ΔT fwd Power cycle life data) is stored. ΔT fwd The power cycle life data can be obtained from, for example, a data sheet provided by a switch element manufacturer.

[0066] The cumulative damage amount generating unit 42 calculates the number of power cycles corresponding to each thermal cycle as ΔT fwd The power cycle life data storage unit 43 is referenced, and the damage amount for each thermal cycle is calculated using the cumulative fatigue damage rule, and is cumulatively added.

[0067] The data of the amount of accumulated damage calculated by the accumulated damage amount generating unit 42 is output to an accumulated damage amount / ΔR converting unit 44. The accumulated damage amount / ΔR converting unit 44 is provided with a data storage unit 441. The data storage unit 441 stores the amount of change in thermal resistance ΔR of the solder layer m9 under the FWD chip, which corresponds to the amount of accumulated damage calculated in advance by measurement or analysis. fwd solder1 The value is stored.

[0068] The cumulative damage amount / ΔR conversion unit 44 refers to the data storage unit 441 to calculate the thermal resistance change amount ΔR corresponding to the cumulative damage amount output from the cumulative damage amount generation unit 42. fwd solder1 Then, the cumulative damage amount / ΔR conversion unit 44 calculates the thermal resistance change amount ΔR fwd solder1 to the FWD chip-case temperature estimating unit 23, and the FWD chip-case thermal impedance Z th(fwd-case) Correct the following.

[0069] <Effects of the second embodiment> As described above, according to the second embodiment, the IGBT chip temperature T igbt ΔT corresponding to igbt Depending on the degree of power cycle deterioration, the IGBT chip-case thermal impedance Z th(igbt-case) By further correcting the above, the IGBT chip temperature T igbt ΔT corresponding to igbt High-precision IGBT chip temperature T taking into account temperature rise due to power cycle degradation igbt This makes it possible to estimate the overheating time, thereby enabling more accurate overheating protection even for equipment with an advanced operating time.

[0070] According to the second embodiment, the FWD chip temperature T fwd ΔT corresponding to fwd Depending on the degree of power cycle deterioration, the FWD chip-to-case thermal impedance Z th(fwd-case) By further correcting the FWD chip temperature T fwd ΔT corresponding to fwd High-precision FWD chip temperature T taking into account temperature rise due to power cycle degradation fwd This makes it possible to estimate the overheating time, thereby enabling more accurate overheating protection even for equipment with an advanced operating time.

[0071] <Other embodiments> The scope of the present invention is not limited to the exemplary embodiments shown and described, but includes all embodiments that achieve the same effect as the object of the present invention. Furthermore, the scope of the present invention is not limited to the combination of the features of the invention defined by the claims, but may be defined by any desired combination of specific features among all the respective features disclosed. [Explanation of symbols]

[0072] 1 Power conversion device 2,2A computing unit 3. User Interface 11 Inverter main circuit 12 Motor 13 Input Voltage Detector 14 Output voltage detector 15 Output current detector 16 Controller 17 Finn 18 Fin temperature sensor 21 IGBT element loss estimation section 22 IGBT chip-case temperature estimation section 23 FWD chip-case temperature estimation section 24 Case-fin temperature estimation section 25 Temperature calculation section 26, 31, 41 Heat cycle conversion section 27, 32, 42 Accumulative damage generator 28 T c Power cycle life data storage 29, 34, 44 Accumulative damage / ΔR conversion section 33 ΔT igbt Power cycle life data storage 43 Tfwd power cycle life data storage 111 IGBT element chip 112 FWD Chip 113 Terminal 251,252,253 adder NW1, NW2, NW3 communication lines m1 IGBT element chip lower solder layer m2 1st copper layer m3 ceramic statue m4 2nd copper layer m5 base solder layer m6 base plate m9 FWD chip bottom solder layer m10 terminal solder layer m11 3rd copper layer m12 case

Claims

1. a switching circuit having a switching element chip accommodated in a case and fins for cooling the switching element chip; A temperature sensor for detecting a temperature of the fin; A control unit that controls on / off of the switching element chip; a loss estimation unit that estimates a chip loss of the switching element chip based on control information used for controlling on / off of the switching element chip; a case temperature estimating unit that estimates a case temperature based on a chip loss of the switching element chip, a stored case-to-fin thermal impedance, and a temperature of the fin detected by the temperature sensor; a switching element chip temperature estimating unit that estimates a temperature of the switching element chip based on the case temperature, a chip loss of the switching element chip, and a stored switching element chip-to-case thermal impedance; a first conversion unit that converts the case temperature into a first thermal cycle; a first cumulative damage amount generating unit that obtains first life data for the first thermal cycle and generates a first cumulative damage amount due to the first thermal cycle based on the first thermal cycle and the first life data; a first thermal impedance correction unit that generates a first thermal resistance change amount for correcting the case-fin thermal impedance and a second thermal resistance change amount for correcting the switching element chip-case thermal impedance based on the first cumulative damage amount, corrects the case-fin thermal impedance stored in the case temperature estimating unit based on the first thermal resistance change amount, and corrects the switching element chip-case thermal impedance stored in the switching element chip temperature estimating unit based on the second thermal resistance change amount; A power conversion device comprising:

2. 2. The power conversion device according to claim 1, wherein the first cumulative damage amount generation unit includes a data storage unit that stores the first life data in correspondence with the first thermal cycle that is stored in advance, reads out the first life data corresponding to the first thermal cycle output from the first conversion unit from the data storage unit, and generates a first cumulative damage amount due to the first thermal cycle based on the first thermal cycle and the first life data.

3. 2. The power conversion device according to claim 1, wherein the first thermal impedance correction unit includes a data storage unit that stores data on the first thermal resistance change amount and the second thermal resistance change amount in correspondence with the first cumulative damage amount stored in advance, and reads out data on the first thermal resistance change amount and the second thermal resistance change amount corresponding to the first cumulative damage amount output from the first cumulative damage amount generation unit from the data storage unit.

4. a second conversion unit that converts the temperature of the switching element chip into a second thermal cycle; a second cumulative damage amount generating unit that obtains second life data for the second thermal cycle and generates a second cumulative damage amount due to the second thermal cycle based on the second thermal cycle and the second life data; a second thermal impedance correction unit that generates a third thermal resistance change amount for correcting the switching element chip-case thermal impedance based on the second accumulated damage amount, and corrects the switching element chip-case thermal impedance stored in the switching element chip temperature estimation unit based on the third thermal resistance change amount; The power converter of claim 1 further comprising:

5. the switching circuit is accommodated in the case and includes a diode chip for protecting the switching element chip; the loss estimation unit estimates a chip loss of the diode chip, a diode chip temperature estimator that estimates a temperature of the diode chip based on the case temperature, a chip loss of the diode chip, and a stored diode chip-case thermal impedance; 2. The power conversion device according to claim 1, wherein the first thermal impedance correction unit generates a fourth thermal resistance change amount for correcting the diode chip-case thermal impedance based on the first cumulative damage amount, and corrects the diode chip-case thermal impedance stored in the diode chip temperature estimation unit based on the fourth thermal resistance change amount.

6. a third conversion unit that converts the temperature of the diode chip into a third thermal cycle; a third cumulative damage amount generating unit that obtains third life data for the third thermal cycle and generates a third cumulative damage amount due to the third thermal cycle based on the third thermal cycle and the third life data; a third thermal impedance correction unit that generates a fifth thermal resistance change amount for correcting the diode chip-case thermal impedance based on the third cumulative damage amount, and corrects the diode chip-case thermal impedance stored in the diode chip temperature estimation unit based on the fifth thermal resistance change amount; The power converter of claim 5 further comprising:

7. 5. The power conversion device according to claim 4, wherein the second cumulative damage amount generation unit includes a data storage unit that stores the second life data in correspondence with the second thermal cycle that is stored in advance, reads out the second life data corresponding to the second thermal cycle output from the second conversion unit from the data storage unit, and generates a second cumulative damage amount due to the second thermal cycle based on the second thermal cycle and the second life data.

8. 5. The power conversion device according to claim 4, wherein the second thermal impedance correction unit includes a data storage unit that stores data on the third thermal resistance change amount in correspondence with the second cumulative damage amount that is stored in advance, and reads out from the data storage unit data on the third thermal resistance change amount that corresponds to the second cumulative damage amount output from the second cumulative damage amount generation unit.

9. 7. The power conversion device according to claim 6, wherein the third cumulative damage amount generation unit includes a data storage unit that stores the third life data in correspondence with the third thermal cycle that is stored in advance, reads out the third life data corresponding to the third thermal cycle output from the third conversion unit from the data storage unit, and generates a third cumulative damage amount due to the third thermal cycle based on the third thermal cycle and the third life data.

10. 7. The power conversion device according to claim 6, wherein the third thermal impedance correction unit includes a data storage unit that stores data on the fifth thermal resistance change amount in correspondence with the third cumulative damage amount that is stored in advance, and reads out from the data storage unit the data on the fifth thermal resistance change amount that corresponds to the third cumulative damage amount output from the third cumulative damage amount generation unit.

11. The power conversion device according to claim 1 , wherein the loss estimation unit uses, as the control information, an input voltage of the switching circuit, an output voltage of the switching circuit, an output current of the switching circuit, a switching frequency, a modulation method, and a current command value.

12. A deterioration diagnosis method for a power conversion device including a switching circuit having a switching element chip accommodated in a case and a fin for cooling the switching element chip, a temperature sensor for detecting a temperature of the fin, and a control unit for controlling on / off of the switching element chip, comprising: estimating a chip loss of the switching element chip based on control information used for controlling on / off of the switching element chip; estimating a case temperature based on a chip loss of the switching element chip, a stored case-to-fin thermal impedance, and a temperature of the fin detected by the temperature sensor; estimating a temperature of the switching element chip based on the case temperature, a chip loss of the switching element chip, and a stored switching element chip-to-case thermal impedance; converting the case temperature into a thermal cycle; determining life data for the thermal cycle, and generating an amount of cumulative damage caused by the thermal cycle based on the thermal cycle and the life data; generating a first thermal resistance change amount for correcting the case-fin thermal impedance and a second thermal resistance change amount for correcting the switching element chip-case thermal impedance based on the cumulative damage amount, correcting the case-fin thermal impedance based on the first thermal resistance change amount, and correcting the switching element chip-case thermal impedance based on the second thermal resistance change amount; A deterioration diagnosis method for a power conversion device comprising:

13. a loss estimation unit that estimates chip loss of the switching element chip based on control information that is output from a power conversion device including a switching circuit having a switching element chip accommodated in a case and fins for cooling the switching element chip and that is used to control on / off of the switching element chip; a case temperature estimating unit that estimates a case temperature based on a chip loss of the switching element chip, a stored case-to-fin thermal impedance, and a temperature of the fin output from the power conversion device; a switching element chip temperature estimating unit that estimates a temperature of the switching element chip based on the case temperature, a chip loss of the switching element chip, and a stored switching element chip-to-case thermal impedance; A conversion unit for converting the case temperature into a thermal cycle; a cumulative damage amount generating unit that calculates life data for the thermal cycle and generates a cumulative damage amount due to the thermal cycle based on the thermal cycle and the life data; a thermal impedance correction unit that generates a first thermal resistance change amount for correcting the case-fin thermal impedance and a second thermal resistance change amount for correcting the switching element chip-case thermal impedance based on the cumulative damage amount, corrects the case-fin thermal impedance stored in the case temperature estimation unit based on the first thermal resistance change amount, and corrects the switching element chip-case thermal impedance stored in the switching element chip temperature estimation unit based on the second thermal resistance change amount; A degradation calculation device comprising:

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