Power Conversion Equipment

Abstract

To provide a power conversion device capable of detecting the deterioration of a semiconductor element.SOLUTION: A power conversion device includes a power semiconductor element including a first main electrode and a second main electrode, a first terminal electrically connected to the first main electrode, a second terminal electrically connected to the second main electrode, a voltage detection unit that detects voltage between both terminals of the first terminal and the second terminal, a temperature detection unit that detects the temperature of the power semiconductor element, and a control unit that determines the deterioration of the power semiconductor element by comparing the voltage detected in a state where both terminals are in conduction, and the threshold voltage that changes according to the temperature detected in the state where both terminals are in conduction.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present disclosure relates to a power conversion device. [Background technology]

[0002] In recent years, the use of power conversion devices has expanded to include applications requiring high reliability (such as power systems and mobile objects), and the demand for high reliability of power conversion devices has increased accordingly. In response to this demand, there are growing expectations for the realization of predictive maintenance that can predict failures and take measures in advance.

[0003] On the other hand, power semiconductor modules are one of the main causes of failures in power conversion devices. It is known that the main failures of power semiconductor modules are caused by thermal stresses that are repeatedly generated by current conduction and switching operations, which deteriorate the bonding wires and solder. As the deterioration of the bonding wires and solder progresses, the conduction resistance between the main terminals when the power semiconductor module is in the on state (conducting state) increases, and the voltage Von between the main terminals when the power semiconductor module is in the conducting state increases. Therefore, in theory, it is said that the deterioration of the power semiconductor module can be detected by detecting the increase in the voltage Von.

[0004] However, in reality, the increase in voltage Von due to degradation is smaller than the increase in voltage Von due to changes in the current flowing between the main terminals or changes in the temperature of the power semiconductor module, so it is not easy to detect the increase in voltage Von due to degradation.

[0005] Therefore, a technique is known in which the current dependence and temperature dependence of the voltage Von are minimized by detecting the voltage Von at a current value IX at which the temperature dependence of the voltage Von is minimized (see, for example, Patent Document 1). [Prior art documents] [Patent documents]

[0006] [Patent Document 1] JP 2010-220470 A Summary of the Invention [Problem to be solved by the invention]

[0007] However, the voltage Von at the current value IX varies depending on the type of power semiconductor element, and the current value IX is often close to the rated current of the power semiconductor element. In this case, since the voltage Von is detected at the current value IX close to the rated current, in applications where operation is mainly performed under medium to light loads, the voltage Von may not be detected as frequently as required. As a result, for example, there is a risk that the semiconductor element will deteriorate.

[0008] The present disclosure provides a power conversion device capable of detecting deterioration of a semiconductor element. [Means for solving the problem]

[0009] In one aspect of the present disclosure, a power semiconductor element having a first main electrode and a second main electrode; a first terminal electrically connected to the first main electrode; a second terminal electrically connected to the second main electrode; a voltage detection unit that detects a voltage between the first terminal and the second terminal; a temperature detection unit for detecting a temperature of the power semiconductor element; The present invention provides a power conversion device that includes a control unit that determines deterioration of the power semiconductor element by comparing the voltage detected when the two terminals are in a conductive state with a threshold voltage that varies depending on the temperature and is detected when the two terminals are in a conductive state. Effect of the Invention

[0010] According to one aspect of the present disclosure, deterioration of a semiconductor element can be detected. [Brief description of the drawings]

[0011] [Figure 1] 1 is a diagram illustrating an example of the overall configuration of a power conversion device according to a first embodiment. [Diagram 2] FIG. 2 is a diagram showing a first configuration example of a functional block for detecting deterioration on the IGBT chip side. [Diagram 3] 4A to 4C are diagrams illustrating examples of waveforms at various parts of a first exemplary configuration of a functional block that detects deterioration on the IGBT chip side. [Figure 4] FIG. 2 is a diagram illustrating a first configuration example of a functional block that detects deterioration on the FWD chip side. [Diagram 5] 11A to 11C are diagrams illustrating examples of waveforms at various parts of a first configuration example of a functional block that detects deterioration on the FWD chip side. [Figure 6] FIG. 13 is a diagram showing a second configuration example of a functional block for detecting deterioration on the IGBT chip side. [Figure 7] 11 is a diagram illustrating waveforms at various parts of a second configuration example of a functional block that detects deterioration on the IGBT chip side. FIG. [Figure 8] FIG. 11 is a diagram illustrating an example of the overall configuration of a power conversion device according to a second embodiment. [Figure 9] FIG. 13 is a diagram showing a third configuration example of a functional block for detecting deterioration on the IGBT chip side. [Figure 10] 13 is a diagram illustrating waveforms at various parts of a third exemplary configuration of a functional block that detects deterioration on the IGBT chip side. FIG. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0012] Hereinafter, a number of embodiments according to the present disclosure will be described with reference to the drawings.

[0013] Fig. 1 is a diagram showing an example of the overall configuration of a power conversion device according to a first embodiment. A power conversion device 101 shown in Fig. 1 includes a main circuit unit 1 that converts DC power supplied from a DC power supply unit 3 into AC power to be supplied to a load 4, and a control unit 2 that controls the power conversion operation of the main circuit unit 1. Fig. 1 illustrates an example in which the main circuit unit 1 converts DC power into three-phase AC power.

[0014] In the example shown in FIG. 1, the main circuit unit 1 includes a plurality of power semiconductor modules 11-16, a plurality of gate driving units 21-26, and a current detection unit 30.

[0015] In addition, FIG. 1 illustrates, as an example of the power semiconductor module, an IGBT module in a 1-in-1 package incorporating an IGBT chip for one arm of an inverter and a diode chip (FWD chip) connected in anti-parallel thereto. IGBT is an abbreviation for Insulated Gate Bipolar Transistor, the IGBT chip is an example of a power semiconductor element, and the FWD chip is an example of a rectifier element. However, the package configuration of the power semiconductor module may be other types of package configurations such as 6-in-1, and the power semiconductor element configured in the power semiconductor module may be other types of power semiconductor elements such as MOSFET. MOSFET is an abbreviation for Metal Oxide Semiconductor Field Effect Transistor. Furthermore, the multiple power semiconductor modules 11-16 each have the same configuration, and the multiple gate drive units 21-26 each have the same configuration. Therefore, for convenience, the following description will be given by taking the upper arm of the u-phase as an example.

[0016] 1, the power semiconductor module 11 of the upper arm of the u-phase has an IGBT chip Q1, an FWD chip D1, and a diode 11d for temperature detection. The power semiconductor module 11 also has a first main terminal C1, a second main terminal E1, a gate terminal SG1, an emitter terminal SE1, a sense anode terminal SA1, and a sense cathode terminal SK1. The first main terminal C1 is an example of a first terminal, the second main terminal E1 is an example of a second terminal, and the gate terminal SG1 is an example of a control terminal.

[0017] The IGBT chip Q1 is an example of a switching element (semiconductor element) having a collector electrode 11c, an emitter electrode 11e, and a gate electrode 11g. The collector electrode 11c is an example of a first main electrode, the emitter electrode 11e is an example of a second main electrode, and the gate electrode 11g is an example of a control electrode.

[0018] The FWD chip D1 is an example of a rectifying element (semiconductor element) having an anode electrode 11a and a cathode electrode 11k.

[0019] The first main terminal C1 is electrically connected to the collector electrode 11c and the cathode electrode 11k via at least one connection member (e.g., bonding wire, solder, etc.). The second main end E1 is electrically connected to the emitter electrode 11e and the anode electrode 11a via at least one connection member. The gate terminal SG1 is electrically connected to the gate electrode 11g via at least one connection member. The emitter terminal SE1 is electrically connected to the emitter electrode 11e and the anode electrode 11a via at least one connection member. The sense anode terminal SA1 is electrically connected to the anode of the temperature detection diode 11d via at least one connection member. The sense cathode terminal SK1 is electrically connected to the cathode of the temperature detection diode 11d via at least one connection member.

[0020] The gate driver 21 is a driver circuit including a pre-driver PD1, a temperature detection circuit Temp1, and a voltage detection circuit Vce1.

[0021] The pre-driver PD1 is a circuit that drives the gate electrode 11g of the IGBT chip Q1 in response to an ON or OFF switching command S1 supplied from the control unit 2.

[0022] The temperature detection circuit Temp1 is an example of a temperature detection unit ("temperature detection unit" in the claims) that supplies a constant current to each of the temperature detection diodes 11d incorporated in the IGBT chip Q1 and the FWD chip D1 in the power semiconductor module 11. The temperature detection circuit Temp1 detects the IGBT chip temperature Tj,igbt1 and the FWD chip temperature Tj,fwd1 by monitoring the voltage drop of the diode 11d, and transmits the detected values ​​to the control unit 2.

[0023] The voltage detection circuit Vce1 detects a voltage Vce_on1 between the main terminals when the IGBT chip Q1 side or the FWD chip D1 side of the power semiconductor module 11 is in the on state, and transmits it to the control unit 2. Between the main terminals is between the first main terminal C1 and the second main terminal C2.

[0024] The current detection unit 30 is a current sensor that detects three-phase AC currents iu, iv, and iw flowing between the power semiconductor modules 11 to 16 and the load 4, and transmits the detected currents to the control unit 2.

[0025] The control unit 2 is a control device including a processor such as a CPU (Central Processing Unit) and a memory. The functions of the control unit 2 are realized by the processor operating according to a program stored in the memory. The functions of the control unit 2 may be realized by a FPGA (Field Programmable Gate Array) or an ASIC (Application Specific Integrated Circuit).

[0026] Fig. 2 is a diagram showing a first configuration example of a functional block for detecting deterioration on the IGBT chip side. Fig. 3 is a diagram showing waveforms of each part of the first configuration example of the functional block for detecting deterioration on the IGBT chip side. The control unit 2 of the power conversion device 101 according to the first embodiment may be provided with the deterioration detection function shown in Fig. 2.

[0027] The control unit 2 has a storage unit 41 that stores on-voltage data on the IGBT chip side, an adjustment unit 42 that adjusts the judgment level, a judgment unit 43 that judges signs of failure on the IGBT chip side, and a limiting unit 44 that limits the lower limit of the u-phase AC current iu (load current Iu).

[0028] The limiting unit 44 outputs zero when the load current Iu detected by the current detection unit 30 is equal to or less than zero, and outputs the value of the load current Iu as is when the load current Iu is greater than zero, and sets the output value as Iu_p.

[0029] The storage unit 41 stores a voltage Vce_ini1 between the main terminals when a current is conducted from the first main terminal C1 to the second main terminal E1 during a period when the switching command S1 is on at the time of shipment or initial operation of the power conversion device 101. Between the main terminals means between the first main terminal C1 and the second main terminal E1. The voltage Vce_ini1 is saved in the storage unit 41 as dependent data on the current (output value Iu_p) flowing between the main terminals and the IGBT chip temperature Tj,igbt1.

[0030] The storage unit 41 receives the IGBT chip temperatures Tj, igbt1 and the output value Iu_p during operation of the power conversion device 101, compares these values ​​with the dependent data, and outputs the voltage Vce_ini1 corresponding to these values.

[0031] The adjustment unit 42 outputs the threshold value Vce_th1 obtained by multiplying the voltage Vce_ini1 by a preset magnification factor. In the example shown in FIG. 2, the magnification factor is set to 1.05.

[0032] The determination unit 43 compares the voltage Vce_on1 between the main terminals when a current is conducted from the first main terminal C1 to the second main terminal E2 during the period when the switching command S1 is on with a threshold Vce_th1 during operation of the power conversion device 101. When the voltage Vce_on1 exceeds the threshold Vce_th1, the determination unit 43 outputs a determination value indicating that there is deterioration on the IBGT chip side (there is a sign of failure).

[0033] When a judgment value indicating the presence of a failure sign is output from the judgment unit 43, the control unit 2 notifies an external device of the power conversion device 101 or a user that there is a failure sign of the IGBT chip Q1. The control unit 2 may notify that there is a failure sign of the power semiconductor module 11 mounting the IGBT chip Q1, or that there is a failure sign of the main circuit unit 1 mounting the power semiconductor module 11, or that there is a failure sign of the power conversion device 101 mounting the main circuit unit 1. By being notified of the presence of the failure sign, it becomes possible to take maintenance measures before a failure occurs on the IGBT chip Q1 side.

[0034] 3 shows a continuous waveform for convenience, but in reality, it is assumed that the control unit 2 is configured by a microcomputer or the like, and therefore the calculation processing within the control unit 2 handles discrete values. Also, since the voltage Vce_on1 is detected while the power conversion device 101 is in operation, it is susceptible to the influence of noise, which may lead to malfunction in the determination of the failure sign. To prevent this, for example, the determination unit 43 may output a determination value indicating the presence of a failure sign when the determination that there is a failure sign occurs multiple times within a predetermined period.

[0035] In this way, the control unit 2 shown in FIG. 2 can determine the deterioration of the IGBT chip Q1 by comparing the voltage Vce_on1 detected by the voltage detection circuit Vce1 when the main terminals are in a conductive state with the voltage Vce_ini1 (threshold Vce_th1) that changes according to the IGBT chip temperature Tj,igbt1 detected by the temperature detection circuit Temp1 when the main terminals are in a conductive state. The voltage Vce_ini1 (threshold Vce_th1) is a value that changes according to the IGBT chip temperature Tj,igbt1 and the output value Iu_p detected when the main terminals are in a conductive state. In the example shown in FIG. 2, the control unit 2 compares the voltage Vce_on1 detected when a current flows from the first main terminal C1 to the second main terminal E1 with the voltage Vce_ini1 (threshold Vce_th1) that changes according to the IGBT chip temperature Tj,igbt1 detected when a current flows from the first main terminal C1 to the second main terminal E1.

[0036] Moreover, the control unit 2 has a configuration similar to that of FIG. 2, and is therefore capable of determining the deterioration of the other IGBT chips Q2 to Q6.

[0037] Deterioration of a power semiconductor element such as an IGBT chip may include not only deterioration of the power semiconductor element itself, but also deterioration of connection members (such as bonding wires and solder) connected to the power semiconductor element.

[0038] Fig. 4 is a diagram showing a first configuration example of a functional block that detects deterioration on the FWD chip side. Fig. 5 is a diagram showing examples of waveforms of each part of the first configuration example of a functional block that detects deterioration on the FWD chip side. The control unit 2 of the power conversion device 101 according to the first embodiment may be provided with the deterioration detection function shown in Fig. 4.

[0039] The control unit 2 includes a storage unit 51 that stores on-voltage data on the FWD chip side, an adjustment unit 52 that adjusts the judgment level, a judgment unit 53 that judges signs of failure on the FWD chip side, a limiting unit 54 that limits the u-phase AC current iu (load current Iu), and an inversion unit 55 that inverts the polarity of the voltage Vce_on1.

[0040] The limiting unit 54 outputs zero when the load current Iu detected by the current detection unit 30 is equal to or greater than zero, and outputs the value of the load current Iu with the polarity reversed when the load current Iu is less than zero, and designates the output value as Iu_n.

[0041] The storage unit 51 stores a voltage Vce_ini1 between the main terminals when a current is conducted from the second main terminal E1 to the first main terminal C1 at the time of shipment or initial operation of the power conversion device 101. The voltage Vce_ini1 is saved in the storage unit 51 as dependent data on the current (output value Iu_n) flowing between the main terminals and the FWD chip temperature Tj,fwd1.

[0042] The storage unit 51 receives the FWD chip temperatures Tj, fwd1 and the output value Iu_n during operation of the power conversion device 101, and outputs the voltage Vce_ini1 after comparing these values ​​with the dependent data.

[0043] The adjustment unit 52 outputs the threshold value Vce_th1 obtained by multiplying the voltage Vce_ini1 by a preset magnification factor. In the example shown in FIG 4, the magnification factor is set to 1.05.

[0044] The determination unit 53 compares the voltage Vce_on1' between the main terminals during operation of the power conversion device 101 (a voltage obtained by inverting the polarity of the voltage Vce_on1 by the inversion unit 55) with a threshold value Vce_th1. When the voltage Vce_on1' exceeds the threshold value Vce_th1, the determination unit 53 outputs a determination value indicating that there is deterioration on the FWD chip side (there is a sign of failure).

[0045] When a determination value indicating the presence of a failure sign is output from the determination unit 43, the control unit 2 notifies an external device of the power conversion device 101 and a user that there is a failure sign in the FWD chip D1. The control unit 2 may notify that there is a failure sign in the power semiconductor module 11 mounting the FWD chip D1, or that there is a failure sign in the main circuit unit 1 mounting the power semiconductor module 11, or that there is a failure sign in the power conversion device 101 mounting the main circuit unit 1. By being notified of the presence of the failure sign, it becomes possible to take maintenance action before a failure occurs on the FWD chip D1 side.

[0046] 5 shows a continuous waveform for convenience, but in reality, it is assumed that the control unit 2 is configured by a microcomputer or the like, and therefore the calculation processing within the control unit 2 handles discrete values. Also, since the voltage Vce_on1 is detected while the power conversion device 101 is in operation, it is susceptible to the influence of noise, which may lead to malfunction in the determination of the failure sign. To prevent this, for example, the determination unit 53 may output a determination value indicating the presence of a failure sign when the determination that there is a failure sign occurs multiple times within a predetermined period.

[0047] In this way, the control unit 2 shown in Fig. 4 can determine the deterioration of the FWD chip D1 by comparing the voltage Vce_on1 detected by the voltage detection circuit Vce1 when the main terminals are in a conductive state with the voltage Vce_ini1 (threshold Vce_th1) that changes according to the FWD chip temperature Tj,fwd1 detected by the temperature detection circuit Temp1 when the main terminals are in a conductive state. The voltage Vce_ini1 (threshold Vce_th1) is a value that changes according to the FWD chip temperature Tj,fwd1 and the output value Iu_n detected when the main terminals are in a conductive state. In the example shown in Fig. 4, the control unit 2 compares the voltage Vce_on1 detected when a current flows from the second main terminal E1 to the first main terminal C1 with the voltage Vce_ini1 (threshold Vce_th1) that changes according to the FWD chip temperature Tj,fwd1 detected when a current flows from the second main terminal E1 to the first main terminal C1.

[0048] Moreover, the control unit 2 has a configuration similar to that in FIG. 4, and is therefore capable of determining the deterioration of the other FWD chips D2 to D6.

[0049] Note that deterioration of a rectifying element such as an FWD chip may include not only deterioration of the rectifying element itself, but also deterioration of connection members (such as bonding wires and solder) connected to the rectifying element.

[0050] Fig. 6 is a diagram showing a second configuration example of a functional block for detecting deterioration on the IGBT chip side. Fig. 7 is a diagram showing waveforms of each part of the second configuration example of a functional block for detecting deterioration on the IGBT chip side. The control unit 2 of the power conversion device 101 according to the first embodiment may be provided with the deterioration detection function shown in Fig. 6.

[0051] The control unit 2 has a storage unit 61 that stores on-voltage data on the IGBT chip side, an adjustment unit 62 that adjusts the judgment level, a judgment unit 63 that judges signs of failure on the IGBT chip side, a selection unit 66 that selects a current, and a limiting unit 64 that limits the lower limit of the u-phase AC current iu (load current Iu).

[0052] The limiting unit 64 outputs zero when the load current Iu detected by the current detection unit 30 is equal to or less than zero, and outputs the value of the load current Iu as is when the load current Iu exceeds zero, and sets the output value as Iu_p.

[0053] The selection unit 66 samples and holds the IGBT chip temperatures Tj, igbt1 and the voltage Vce_on1 at the timing when the output value Iu_p exceeds a predetermined current level Ir, and outputs the respective sampled and held values ​​as Tj_sh1 and Vce_on_sh1.

[0054] The storage unit 61 stores a voltage Vce_ini1 between the main terminals when a current is conducted from the first main terminal C1 to the second main terminal E1 during a period in which a switching command S1 is on at the time of shipment or initial operation of the power conversion device 101. The voltage Vce_ini1 is saved in the storage unit 61 as dependent data on the IGBT chip temperature Tj,igbt1 at a predetermined current value Ir flowing between the main terminals.

[0055] The storage unit 61 receives a sample and hold value Tj_sh1 of the IGBT chip temperature during operation of the power conversion device 101, compares the sample and hold value Tj_sh1 with the dependent data, and outputs a voltage Vce_ini1 corresponding to the sample and hold value Tj_sh1.

[0056] The adjustment unit 62 outputs the threshold value Vce_th1 obtained by multiplying the voltage Vce_ini1 by a preset magnification factor. In the example shown in FIG 6, the magnification factor is set to 1.05.

[0057] The determination unit 63 compares a sample-and-hold value Vce_on_sh1 of the on-voltage with a threshold value Vce_th1 during operation of the power conversion device 101. When the sample-and-hold value Vce_on_sh1 exceeds the threshold value Vce_th1, the determination unit 63 outputs a determination value indicating that there is degradation on the IBGT chip side (there is a sign of failure).

[0058] When a judgment value indicating the presence of a failure sign is output from the judgment unit 63, the control unit 2 notifies an external device of the power conversion device 101 or a user that there is a failure sign of the IGBT chip Q1. The control unit 2 may notify that there is a failure sign of the power semiconductor module 11 mounting the IGBT chip Q1, or that there is a failure sign of the main circuit unit 1 mounting the power semiconductor module 11, or that there is a failure sign of the power conversion device 101 mounting the main circuit unit 1. By being notified of the presence of the failure sign, it becomes possible to take maintenance measures before a failure occurs on the IGBT chip Q1 side.

[0059] 7 shows a continuous waveform for convenience, but in reality, it is assumed that the control unit 2 is configured by a microcomputer or the like, and therefore the calculation processing within the control unit 2 handles discrete values. Also, since the voltage Vce_on1 is detected while the power conversion device 101 is in operation, it is susceptible to the influence of noise, which may lead to malfunction in the determination of the failure sign. To prevent this, for example, the determination unit 63 may output a determination value indicating the presence of a failure sign when the determination that there is a failure sign occurs multiple times within a predetermined period.

[0060] In the second configuration example shown in FIG. 6, the voltage Vce_ini1 stored in the storage unit 61 does not include current dependency, which has the advantage that the amount of data can be reduced.

[0061] In this way, the control unit 2 shown in Fig. 6 can determine the deterioration of the IGBT chip Q1 by comparing the voltage Vce_on1 (Tj_sh1) detected when the current Iu_p is equal to or greater than the predetermined current value Ir with the voltage Vce_ini1 (threshold Vce_th1) that changes according to the IGBT chip temperature Tj,igbt1 detected when the current Iu_p is equal to or greater than the predetermined current value Ir. Also, by having a configuration similar to that shown in Fig. 6, the control unit 2 can determine the deterioration of the other IGBT chips Q2 to Q6.

[0062] It is also possible to modify the functional block shown in Fig. 6 into a functional block for detecting deterioration on the FWD chip side. Specifically, the selection unit 66 samples and holds the FWD chip temperature Tj,fwd1 and the voltage Vce_on1 at the timing when the output value Iu_n (see Fig. 4) exceeds a predetermined current level Ir, and outputs the respective sample and hold values ​​as Tj_sh1 and Vce_on_sh1. The voltage Vce_ini1 is stored in the storage unit 61 as dependent data for the FWD chip temperature Tj,fwd1 at a predetermined current value Ir flowing between the main terminals. The storage unit 61 receives the sample and hold value Tj,sh1 of the FWD chip temperature during operation of the power conversion device 101, compares the sample and hold value Tj,sh1 with the dependent data, and outputs the voltage Vce_ini1 corresponding to the sample and hold value Tj,sh1. The determination unit 63 compares the voltage Vce_on1' between the main terminals during operation of the power conversion device 101 (the voltage obtained by inverting the polarity of the voltage Vce_on1 by the inversion unit 55 (see FIG. 4)) with the threshold value Vce_th1. When the voltage Vce_on1' exceeds the threshold value Vce_th1, the determination unit 63 outputs a determination value indicating that there is deterioration on the FWD chip side (there is a sign of failure).

[0063] Therefore, according to this modification of the functional blocks, the control unit 2 can determine the deterioration of the FWD chip D1 by comparing the voltage Vce_on1 (Tj_sh1) detected when the current Iu_p is equal to or greater than the predetermined current value Ir with the voltage Vce_ini1 (threshold Vce_th1) that changes according to the FWD chip temperature Tj,fwd1 detected when the current Iu_p is equal to or greater than the predetermined current value Ir. Furthermore, according to this modification of the functional blocks, the control unit 2 can determine the deterioration of the other FWD chips Q2 to Q6.

[0064] Fig. 8 is a diagram showing an example of the overall configuration of a power conversion device according to the second embodiment. In the second embodiment, the description of the same configuration as in the first embodiment will be omitted or simplified by invoking the above description. The power conversion device 102 shown in Fig. 8 includes a main circuit unit 1 that converts DC power supplied from a DC power supply unit 3 into AC power to be supplied to a load 4, and a control unit 2 that controls the power conversion operation of the main circuit unit 1.

[0065] 8, the main circuit unit 1 includes a plurality of power semiconductor modules 11-16, a plurality of gate drive units 21-26, a current detection unit 30, and a heat sink temperature detection unit 80. For the same reasons as in the first embodiment, the following description will be given by taking the upper arm of the u-phase as an example for convenience.

[0066] The gate driver 21 is a driver circuit including a pre-driver PD1 and a voltage detection circuit Vce1.

[0067] The pre-driver PD1 is a circuit that drives the gate electrode 11g of the IGBT chip Q1 in response to an ON or OFF switching command S1 supplied from the control unit 2.

[0068] The voltage detection circuit Vce1 detects a voltage Vce_on1 between the main terminals when the IGBT chip Q1 side or the FWD chip D1 side of the power semiconductor module 11 is in the on state, and transmits the detected voltage Vce_on1 to the control unit 2.

[0069] The current detection unit 30 is a current sensor that detects three-phase AC currents iu, iv, and iw flowing between the power semiconductor modules 11 to 16 and the load 4, and transmits the detected currents to the control unit 2.

[0070] The heat sink temperature detection unit 80 is a temperature sensor that transmits to the control unit 2 a detected temperature value Th of the heat sink that cools the power semiconductor module.

[0071] The DC voltage detection unit 70 is a circuit that detects the DC voltage value Vin on the DC power supply unit 3 side of the main circuit unit 1 and transmits the detected value to the control unit 2.

[0072] Fig. 9 is a diagram showing a third configuration example of a functional block for detecting deterioration on the IGBT chip side. Fig. 10 is a diagram showing waveforms of each part of the third configuration example of a functional block for detecting deterioration on the IGBT chip side. The control unit 2 of the power conversion device 102 according to the second embodiment may be provided with the deterioration detection function shown in Fig. 9.

[0073] The control unit 2 has a storage unit 91 that stores on-voltage data on the IGBT chip side, an adjustment unit 92 that adjusts a judgment level, a judgment unit 93 that judges signs of failure on the IGBT chip side, a limiting unit 94 that limits the lower limit of the u-phase AC current iu (load current Iu), and an estimation unit 97 that estimates the IGBT chip temperature.

[0074] The estimation unit 97 calculates the loss generated in the IGBT chip and the IGBT chip temperature Tj_est,igbt1 based on the heat sink temperature detection value Th obtained by the heat sink temperature detection unit 80, the DC voltage value Vin obtained by the DC voltage detection unit 70, and the output voltage command vu_ref, current command value Iu_ref, and carrier frequency fc generated by the control unit 2. A specific calculation method may be a known method. The estimation unit 97 is an example of the "temperature detection unit" in the claims.

[0075] The limiting unit 94 outputs zero when the load current Iu detected by the current detection unit 30 is equal to or less than zero, and outputs the value of the load current Iu as is when the load current Iu exceeds zero, and sets the output value as Iu_p.

[0076] The storage unit 91 stores a voltage Vce_ini1 between the main terminals when a current is conducted from the first main terminal C1 to the second main terminal E1 during a period in which a switching command S1 is on at the time of shipment or initial operation of the power conversion device 101. The voltage Vce_ini1 is saved in the storage unit 91 as dependent data on the current (output value Iu_p) flowing between the main terminals and the IGBT chip temperature Tj_est,igbt1.

[0077] The storage unit 91 receives the IGBT chip temperatures Tj_est, igbt1 and the output value Iu_p during operation of the power conversion device 101, compares these values ​​with the dependent data, and outputs the voltage Vce_ini1 corresponding to these values.

[0078] The adjustment unit 92 outputs the threshold value Vce_th1 obtained by multiplying the voltage Vce_ini1 by a preset magnification factor. In the example shown in FIG. 2, the magnification factor is set to 1.05.

[0079] The determination unit 93 compares the voltage Vce_on1 between the main terminals when a current is conducted from the first main terminal C1 to the second main terminal E2 during the period when the switching command S1 is on with a threshold Vce_th1 during operation of the power conversion device 101. When the voltage Vce_on1 exceeds the threshold Vce_th1, the determination unit 93 outputs a determination value indicating that there is deterioration on the IGBT chip side (there is a sign of failure).

[0080] When a judgment value indicating the presence of a failure sign is output from the judgment unit 93, the control unit 2 notifies an external device of the power conversion device 101 or a user that there is a failure sign of the IGBT chip Q1. The control unit 2 may notify that there is a failure sign of the power semiconductor module 11 mounting the IGBT chip Q1, or that there is a failure sign of the main circuit unit 1 mounting the power semiconductor module 11, or that there is a failure sign of the power conversion device 101 mounting the main circuit unit 1. By being notified of the presence of the failure sign, it becomes possible to take maintenance measures before a failure occurs on the IGBT chip Q1 side.

[0081] 10 shows a continuous waveform for convenience, but in reality, it is assumed that the control unit 2 is configured with a microcomputer or the like, and therefore the calculation processing within the control unit 2 handles discrete values. Also, since the voltage Vce_on1 is detected while the power conversion device 101 is in operation, it is susceptible to the influence of noise, which may lead to malfunction in the determination of the failure sign. To prevent this, for example, the determination unit 93 may output a determination value indicating the presence of a failure sign when the determination that there is a failure sign occurs multiple times within a predetermined period.

[0082] 6 to the functional block shown in Fig. 9, there is an advantage in that the amount of data can be reduced since the voltage Vce_ini1 stored in the storage unit 91 does not need to include current dependency. Also, the functional block shown in Fig. 9 can be modified to a functional block that detects deterioration on the FWD chip side, as described above.

[0083] Although the embodiment has been described above, the present invention is not limited to the above embodiment, and various modifications and improvements, such as combinations with or substitutions for part or all of other embodiments, are possible.

[0084] For example, the power semiconductor element is not limited to a power transistor such as an IGBT, but may be a diode, a thyristor, a gate turn-off thyristor, a triac, or the like. [Explanation of symbols]

[0085] 1 Main circuit section 2. Control section 11~16 Power Semiconductor Modules 21~26 Gate driver 30 Current detection section 70 DC voltage detection section 80 Heat sink temperature detector 101,102 Power conversion device

Claims

1. a power semiconductor element having a first main electrode and a second main electrode; a first terminal electrically connected to the first main electrode; a second terminal electrically connected to the second main electrode; a voltage detection unit that detects a voltage between the first terminal and the second terminal; a temperature detection unit for detecting a temperature of the power semiconductor element; a current detection unit that detects a current flowing between the two terminals; A control unit that controls a power conversion operation; a drive circuit that drives the power semiconductor element in response to a switching command supplied from the control unit, The control unit determines deterioration of the power semiconductor element by comparing the voltage detected during operation of the power conversion device in a first conduction state between the two terminals from the first terminal to the second terminal, with the current detected in the first conduction state and a threshold voltage that changes depending on the temperature detected in the first conduction state.

2. A plurality of arms; A temperature detection unit; A current detection unit; A control unit that controls a power conversion operation, Each of the plurality of arms includes: a power semiconductor element having a first main electrode and a second main electrode; a first terminal electrically connected to the first main electrode; a second terminal electrically connected to the second main electrode; a voltage detection unit that detects a voltage between the first terminal and the second terminal; a drive circuit that drives the power semiconductor element in response to a switching command supplied from the control unit, The temperature detection unit detects a temperature of the power semiconductor element, The current detection unit detects a current flowing between the two terminals, The control unit determines deterioration of the power semiconductor element by comparing, for each of the multiple arms, the voltage detected during operation of the power conversion device in a first conduction state between the two terminals from the first terminal to the second terminal, with the current detected in the first conduction state and a threshold voltage detected in the first conduction state that changes depending on the temperature.

3. A power conversion device as described in claim 1 or 2, wherein the control unit derives the threshold voltage by calculating the voltage corresponding to the current detected in the first conduction state and the temperature detected in the first conduction state based on the relationship between the current, the temperature and the voltage.

4. 4. The power conversion device according to claim 1, wherein the control unit determines deterioration of the power semiconductor element by comparing the voltage detected in the first conduction state in which the current is equal to or greater than a predetermined current value with the threshold voltage that varies depending on the temperature detected in the first conduction state in which the current is equal to or greater than the predetermined current value.

5. A rectifying element having a cathode and an anode, the first terminal is electrically connected to the first main electrode and the cathode; the second terminal is electrically connected to the second main electrode and the anode; 5. The power conversion device according to claim 1, wherein the control unit determines deterioration of the rectifying element by comparing the voltage detected in a second conduction state between the two terminals from the second terminal to the first terminal with a threshold voltage that changes depending on the temperature detected in the second conduction state.

6. A rectifying element having a cathode and an anode, the first terminal is electrically connected to the first main electrode and the cathode; the second terminal is electrically connected to the second main electrode and the anode; 5. The power conversion device according to claim 1, wherein the control unit determines deterioration of the rectifying element by comparing the voltage detected in a second conduction state between the two terminals from the second terminal to the first terminal with a threshold voltage that changes depending on the current detected in the second conduction state and the temperature detected in the second conduction state.

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