Power converter and detection device

Abstract

To provide a power conversion device capable of detecting a failure sign or deterioration of a power semiconductor module.SOLUTION: A power conversion device includes a power semiconductor module having a first terminal and a second terminal, a voltage detection unit that detects a voltage between the first terminal and the second terminal, a temperature detection unit that detects a temperature of the power semiconductor module, a current detection unit that detects a current flowing between the two terminals, a control unit that controls a power conversion operation, and a drive circuit that drives the power semiconductor module in response to a switching command supplied from the control unit, and the control unit detects a sign of failure or deterioration of the power semiconductor module by comparing the voltage detected during operation of the power conversion device with a threshold voltage that changes depending on the current and the temperature.SELECTED DRAWING: Figure 2

Description

Technical Field

[0001] The present disclosure relates to a power conversion device and a detection device.

Background Art

[0002] In recent years, power conversion devices have been expanding into applications (such as power systems and moving bodies) that require high reliability, and along with this, the demand for high reliability of power conversion devices has been increasing. In response to this demand, expectations for realizing predictive maintenance that predicts failures and takes preventive measures in advance have been increasing.

[0003] On the other hand, one of the main failure factors of a power conversion device is a power semiconductor module. It is known that the main failure of a power semiconductor module occurs when thermal stress stress repeatedly generated by current conduction and switching operations deteriorates 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, so the voltage Von between the main terminals when the power semiconductor module is in the conducting state rises. Therefore, theoretically, 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 the voltage Von due to deterioration is smaller than the increase in the 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 the voltage Von due to deterioration.

[0005] Therefore, a technique is known in which the voltage Von is detected at a current value IX at which the temperature dependence of the voltage Von is minimized, thereby minimizing the current dependence and temperature dependence of the voltage Von (see, for example, Patent Document 1).

Prior Art Documents

Patent Documents

[0006]

Patent Document 1

[0007] However, the voltage Von at current value IX varies depending on the type of power semiconductor device, and current value IX is often near the rated current of the power semiconductor device. In this case, since voltage Von is detected at current value IX near the rated current, it may not be possible to detect voltage Von at the required frequency in applications where operation is mainly at light to medium loads. As a result, for example, the degradation of the semiconductor device may progress.

[0008] This disclosure provides a power conversion device and a detection device capable of detecting signs of failure or degradation in power semiconductor modules. [Means for solving the problem]

[0009] In one aspect of this disclosure, A power semiconductor module having a first terminal and a second terminal, A voltage detection unit that detects the voltage between the first terminal and the second terminal, A temperature detection unit for detecting the temperature of the power semiconductor module, A current detection unit for detecting the current flowing between the two terminals, A control unit that controls the power conversion operation, A drive circuit that drives the power semiconductor module in response to a switching command supplied from the control unit, Equipped with, The control unit detects signs of failure or degradation of the power semiconductor module by comparing the voltage detected during operation of the power converter with a threshold voltage that changes according to the current and temperature. A power converter is provided. [Effects of the Invention]

[0010] According to one aspect of this disclosure, it is possible to detect signs of failure or degradation in a power semiconductor module. [Brief explanation of the drawing]

[0011] [Figure 1] This figure shows an example of the overall configuration of a power conversion device according to the first embodiment. [Figure 2] This figure shows a first example configuration of a functional block for detecting degradation on the IGBT chip side. [Figure 3] This figure illustrates the waveforms of each part of the first configuration example of a functional block that detects degradation on the IGBT chip side. [Figure 4] This figure shows a first example configuration of a functional block that detects degradation on the FWD chip side. [Figure 5] This figure illustrates the waveforms of each part of the first configuration example of a functional block that detects degradation on the FWD chip side. [Figure 6] This figure shows a second example configuration of a functional block for detecting degradation on the IGBT chip side. [Figure 7] This figure illustrates the waveforms of each part of the second configuration example of a functional block that detects degradation on the IGBT chip side. [Figure 8] This figure shows an example of the overall configuration of a power conversion device according to the second embodiment. [Figure 9] This figure shows a third example configuration of a functional block that detects degradation on the IGBT chip side. [Figure 10] This figure illustrates the waveforms of each part of the third configuration example of a functional block that detects degradation on the IGBT chip side. [Modes for carrying out the invention]

[0012] Hereinafter, several embodiments relating to this 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 the first embodiment. The power conversion device 101 shown in FIG. 1 includes a main circuit section 1 that converts the DC power supplied from the DC power supply section 3 into AC power to be supplied to the load 4, and a control section 2 that controls the power conversion operation of the main circuit section 1. FIG. 1 illustrates a form in which the main circuit section 1 converts DC power into three-phase AC power.

[0014] In the example shown in FIG. 1, the main circuit section 1 includes a plurality of power semiconductor modules 11 to 16, a plurality of gate drive sections 21 to 26, and a current detection section 30.

[0015] Note that in FIG. 1, as a power semiconductor module, an IGBT module in a 1in1 package in which an IGBT chip for one arm of an inverter and a diode chip (FWD chip) connected in anti-parallel thereto are incorporated is illustrated. IGBT is an abbreviation for Insulated Gate Bipolar Transistor, the IGBT chip is an example of a power semiconductor device, and the FWD chip is an example of a rectifying device. However, the package configuration of the power semiconductor module may be other types of package configurations such as 6in1, and the power semiconductor device constituting the power semiconductor module may be other types of power semiconductor devices such as MOSFET. MOSFET is an abbreviation for Metal Oxide Semiconductor Field Effect Transistor. Further, the plurality of power semiconductor modules 11 to 16 have the same configuration, and the plurality of gate drive sections 21 to 26 have the same configuration. Therefore, hereinafter, for the sake of convenience, the upper arm of the u phase will be described as an example.

[0016] In the example shown in Figure 1, the u-phase upper arm power semiconductor module 11 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 rectifier 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 connecting member (e.g., bonding wire, solder, etc.). The second main terminal E1 is electrically connected to the emitter electrode 11e and the anode electrode 11a via at least one connecting member. The gate terminal SG1 is electrically connected to the gate electrode 11g via at least one connecting member. The emitter terminal SE1 is electrically connected to the emitter electrode 11e and the anode electrode 11a via at least one connecting member. The sense anode terminal SA1 is electrically connected to the anode of the temperature sensing diode 11d via at least one connecting member. The sense cathode terminal SK1 is electrically connected to the cathode of the temperature sensing diode 11d via at least one connecting member.

[0020] The gate drive unit 21 is a drive circuit that includes 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 (the "temperature detection unit" in the claims) that supplies a constant current to temperature detection diodes 11d, respectively, which are incorporated into the IGBT chip Q1 and FWD chip D1 within the power semiconductor module 11. The temperature detection circuit Temp1 monitors the voltage drop across the diodes 11d to detect the IGBT chip temperature Tj,igbt1 and the FWD chip temperature Tj,fwd1 and transmits this information to the control unit 2.

[0023] The voltage detection circuit Vce1 detects the voltage Vce_on1 between the main terminals when the IGBT chip Q1 or FWD chip D1 of the power semiconductor module 11 is ON, and transmits it to the control unit 2. The main terminals refer to the terminals between the first main terminal C1 and the second main terminal E1.

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

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

[0026] Figure 2 shows a first example configuration of a functional block for detecting degradation on the IGBT chip side. Figure 3 shows an example of the waveforms of each part of the first example configuration of the functional block for detecting degradation on the IGBT chip side. The control unit 2 of the power converter 101 according to the first embodiment may be equipped with the degradation detection function shown in Figure 2.

[0027] The control unit 2 includes a storage unit 41 for storing on-voltage data from the IGBT chip, an adjustment unit 42 for adjusting the determination level, a determination unit 43 for determining fault indicators on the IGBT chip, and a limiting unit 44 for limiting 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 less than or equal to zero, and outputs the value of the load current Iu as is when the value is greater than zero, and this output value is set to Iu_p.

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

[0030] The storage unit 41 receives the IGBT chip temperature Tj, igbt1 and output value Iu_p during the operation of the power converter 101. These values ​​are compared with the dependency data, and the voltage Vce_ini1 corresponding to these values ​​is output.

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

[0032] The determination unit 43 compares the voltage Vce_on1 between the main terminals when 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 while the power converter 101 is in operation with the threshold Vce_th1. 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 (a sign of failure).

[0033] When the determination unit 43 outputs a determination value indicating the presence of a failure indicator, the control unit 2 notifies external devices and users of the power converter 101 that there is a failure indicator for the IGBT chip Q1. The control unit 2 may also notify that there is a failure indicator for the power semiconductor module 11 on which the IGBT chip Q1 is mounted, or for the main circuit unit 1 on which the power semiconductor module 11 is mounted, or for the power converter 101 on which the main circuit unit 1 is mounted. Notification of the failure indicator makes it possible to take maintenance measures before a failure occurs on the IGBT chip Q1 side.

[0034] Note that although Figure 3 shows a continuous waveform for convenience, in reality, the control unit 2 is expected to be composed of a microcontroller or the like, so the calculation processing inside the control unit 2 will handle discrete values. Also, since the voltage Vce_on1 is detected during the operation of the power converter 101, it is susceptible to noise, which could lead to malfunctions in the fault prediction judgment. To prevent this, for example, the determination unit 43 may output a determination value indicating the presence of a fault if it has determined that there is a fault precursor multiple times within a predetermined period.

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

[0036] Furthermore, by having the same configuration as in Figure 2, the control unit 2 can determine the degradation of the other IGBT chips Q2 to Q6.

[0037] Furthermore, the degradation of power semiconductor devices such as IGBT chips may include not only the degradation of the power semiconductor device itself, but also the degradation of connecting materials (such as bonding wires and solder) connected to the power semiconductor device.

[0038] Figure 4 shows a first example configuration of a functional block for detecting degradation on the FWD chip side. Figure 5 shows an example of the waveforms of each part of the first example configuration of the functional block for detecting degradation on the FWD chip side. The control unit 2 of the power converter 101 according to the first embodiment may be equipped with the degradation detection function shown in Figure 4.

[0039] The control unit 2 includes a storage unit 51 for storing on-voltage data from the FWD chip, an adjustment unit 52 for adjusting the determination level, a determination unit 53 for determining signs of failure on the FWD chip, a limiting unit 54 for limiting the u-phase AC current iu (load current Iu), and an inversion unit 55 for reversing 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 greater than or equal to zero, and outputs the value of the load current Iu with the polarity reversed when it is less than zero, and this output value is denoted as Iu_n.

[0041] The storage unit 51 stores the voltage Vce_ini1 between the main terminals when current is conducted from the second main terminal E1 to the first main terminal C1 during the power converter 101's shipment or initial operation. The voltage Vce_ini1 is stored in the storage unit 51 as dependency data on the current flowing between the main terminals (output value Iu_n) and the FWD chip temperature Tj,fwd1.

[0042] The storage unit 51 receives the FWD chip temperature Tj,fwd1 and output value Iu_n during the operation of the power converter 101. After comparing these values ​​with the dependency data, the voltage Vce_ini1 is output.

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

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

[0045] When the determination unit 43 outputs a determination value indicating the presence of a failure indicator, the control unit 2 notifies external devices and users of the power converter 101 that there is a failure indicator for the FWD chip D1. The control unit 2 may also notify that there is a failure indicator for the power semiconductor module 11 on which the FWD chip D1 is mounted, or for the main circuit unit 1 on which the power semiconductor module 11 is mounted, or for the power converter 101 on which the main circuit unit 1 is mounted. Notification of a failure indicator makes it possible to take maintenance measures before a failure occurs on the FWD chip D1 side.

[0046] Note that although Figure 5 shows a continuous waveform for convenience, in reality, the control unit 2 is expected to be composed of a microcontroller or the like, so the calculation processing inside the control unit 2 will handle discrete values. Also, since the voltage Vce_on1 is detected during the operation of the power converter 101, it is susceptible to noise, which could lead to malfunctions in the fault prediction judgment. To prevent this, for example, the determination unit 53 may output a determination value indicating the presence of a fault if it has determined that there is a fault warning multiple times within a predetermined period.

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

[0048] Furthermore, the control unit 2 has the same configuration as in Figure 4, which allows it to determine the degradation of the other FWD chips D2 to D6.

[0049] Furthermore, the degradation of rectifier elements such as FWD chips may include not only the degradation of the rectifier element itself, but also the degradation of connecting materials (such as bonding wires and solder) connected to the rectifier element.

[0050] Figure 6 shows a second example configuration of a functional block for detecting degradation on the IGBT chip side. Figure 7 shows an example of the waveforms of each part of the second example configuration of the functional block for detecting degradation on the IGBT chip side. The control unit 2 of the power converter 101 according to the first embodiment may be equipped with the degradation detection function shown in Figure 6.

[0051] The control unit 2 includes a storage unit 61 for storing on-voltage data from the IGBT chip, an adjustment unit 62 for adjusting the determination level, a determination unit 63 for determining fault indicators on the IGBT chip, a selection unit 66 for selecting a current, and a limiting unit 64 for limiting 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 less than or equal to zero, and outputs the value of the load current Iu as is when the value is greater than zero, and this output value is set to Iu_p.

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

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

[0055] The storage unit 61 receives the sample-and-hold value Tj_sh1 of the IGBT chip temperature during operation of the power converter 101. The sample-and-hold value Tj_sh1 is compared with the dependency data, and the voltage Vce_ini1 corresponding to the sample-and-hold value Tj_sh1 is output.

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

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

[0058] When the determination unit 63 outputs a determination value indicating the presence of a failure indicator, the control unit 2 notifies external devices and users of the power converter 101 that there is a failure indicator for the IGBT chip Q1. The control unit 2 may also notify that there is a failure indicator for the power semiconductor module 11 on which the IGBT chip Q1 is mounted, or for the main circuit unit 1 on which the power semiconductor module 11 is mounted, or for the power converter 101 on which the main circuit unit 1 is mounted. Notification of the failure indicator makes it possible to take maintenance measures before a failure occurs on the IGBT chip Q1 side.

[0059] Note that although Figure 7 shows a continuous waveform for convenience, in reality, the control unit 2 is expected to be composed of a microcontroller or the like, so the calculation processing inside the control unit 2 will handle discrete values. Also, since the voltage Vce_on1 is detected during the operation of the power converter 101, it is susceptible to noise, which could lead to malfunctions in the fault prediction judgment. To prevent this, for example, the determination unit 63 may output a determination value indicating the presence of a fault if it has determined that there is a fault precursor multiple times within a predetermined period.

[0060] Furthermore, in the second configuration example shown in Figure 6, the voltage Vce_ini1 stored in the storage unit 61 does not include current dependence, which has the advantage of reducing the amount of data.

[0061] As described above, the control unit 2 shown in Figure 6 can determine the degradation of IGBT chip Q1 by comparing the voltage Vce_on1 (Tj_sh1) detected when the current Iu_p is greater than or equal to a predetermined current value Ir with the voltage Vce_ini1 (threshold Vce_th1) which changes according to the IGBT chip temperature Tj,igbt1 detected when the current Iu_p is greater than or equal to a predetermined current value Ir. Furthermore, by having the same configuration as in Figure 6, the control unit 2 can determine the degradation of the other IGBT chips Q2 to Q6.

[0062] Furthermore, the functional block shown in Figure 6 can be modified into a functional block that detects degradation on the FWD chip side. Specifically, the selection unit 66 samples and holds the FWD chip temperature Tj,fwd1 and voltage Vce_on1 when the output value Iu_n (see Figure 4) exceeds a predetermined current level Ir, and outputs the respective sample-hold values ​​as Tj_sh1 and Vce_on_sh1. The voltage Vce_ini1 is stored in the storage unit 61 as dependency 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-hold value Tj,sh1 of the FWD chip temperature during operation of the power converter 101, compares the sample-hold value Tj,sh1 with the dependency data, and outputs the voltage Vce_ini1 corresponding to the sample-hold value Tj,sh1. The determination unit 63 compares the voltage Vce_on1' (the voltage obtained by reversing the polarity of voltage Vce_on1 by the reversal unit 55 (see Figure 4)) between the main terminals during operation of the power converter 101 with the threshold Vce_th1. When the voltage Vce_on1' exceeds the threshold Vce_th1, the determination unit 63 outputs a determination value indicating that there is deterioration on the FWD chip side (a sign of failure).

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

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

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

[0066] The gate drive unit 21 is a drive circuit that includes 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 the voltage Vce_on1 between the main terminals when the IGBT chip Q1 or FWD chip D1 of the power semiconductor module 11 is ON, and transmits it to the control unit 2.

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

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

[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 it to the control unit 2.

[0072] Figure 9 shows a third example configuration of a functional block for detecting degradation on the IGBT chip side. Figure 10 shows an example of the waveforms of each part of the third example configuration of the functional block for detecting degradation on the IGBT chip side. The control unit 2 of the power converter 102 according to the second embodiment may be equipped with the degradation detection function shown in Figure 9.

[0073] The control unit 2 includes a storage unit 91 for storing on-voltage data from the IGBT chip, an adjustment unit 92 for adjusting the determination level, a determination unit 93 for determining fault indicators on the IGBT chip, a limiting unit 94 for limiting the lower limit of the u-phase AC current iu (load current Iu), and an estimation unit 97 for estimating 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, the output voltage command vu_ref, the current command value Iu_ref, and the carrier frequency fc generated by the control unit 2. The specific calculation method may be a known method. Furthermore, 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 less than or equal to zero, and outputs the value of the load current Iu as is when the value is greater than zero, and this output value is set to Iu_p.

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

[0077] The storage unit 91 receives the IGBT chip temperature Tj_est, igbt1 and the output value Iu_p during the operation of the power converter 101. These values ​​are compared with the dependency data, and the voltage Vce_ini1 corresponding to these values ​​is output.

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

[0079] The determination unit 93 compares the voltage Vce_on1 between the main terminals when 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 while the power converter 101 is in operation with the threshold Vce_th1. 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 (a sign of failure).

[0080] When the determination unit 93 outputs a determination value indicating the presence of a failure indicator, the control unit 2 notifies external devices and users of the power converter 101 that there is a failure indicator for the IGBT chip Q1. The control unit 2 may also notify that there is a failure indicator for the power semiconductor module 11 on which the IGBT chip Q1 is mounted, or for the main circuit unit 1 on which the power semiconductor module 11 is mounted, or for the power converter 101 on which the main circuit unit 1 is mounted. By notifying that there is a failure indicator, maintenance measures can be taken before a failure occurs on the IGBT chip Q1 side.

[0081] Note that although Figure 10 shows a continuous waveform for convenience, in reality, the control unit 2 is expected to be composed of a microcontroller or the like, so the calculation processing inside the control unit 2 will handle discrete values. Also, since the voltage Vce_on1 is detected during the operation of the power converter 101, it is susceptible to noise, which could lead to malfunctions in the fault prediction judgment. To prevent this, for example, the determination unit 93 may output a determination value indicating the presence of a fault if it has determined that there is a fault warning multiple times within a predetermined period.

[0082] Furthermore, by adding the selection unit 66 shown in Figure 6 to the functional block shown in Figure 9, it becomes unnecessary to include current dependence in the voltage Vce_ini1 stored in the storage unit 91, thus reducing the amount of data. Also, the functional block shown in Figure 9 can be transformed into a functional block that detects degradation on the FWD chip side, similar to the above.

[0083] Although embodiments have been described above, the present invention is not limited to the embodiments described above. Various modifications and improvements are possible, such as combinations or substitutions with some or all of the other embodiments.

[0084] For example, power semiconductor elements are not limited to power transistors such as IGBTs, but may also include diodes, thyristors, gate turn-off thyristors, triacs, etc. [Explanation of Symbols]

[0085] 1 Main circuit section 2 Control Unit 11-16 Power semiconductor modules 21-26 Gate drive unit 30 Current detection unit 70 DC voltage detection unit 80 Heat sink temperature detection unit 101,102 Power converter

Claims

1. A power semiconductor module having a first terminal and a second terminal, A voltage detection unit that detects the voltage between the first terminal and the second terminal, A temperature detection unit for detecting the temperature of the power semiconductor module, A current detection unit for detecting the current flowing between the two terminals, A control unit that controls the power conversion operation, A drive circuit that drives the power semiconductor module in response to a switching command supplied from the control unit, A power conversion device comprising, The control unit detects signs of failure or degradation of the power semiconductor module by comparing the voltage detected when both terminals are in a first conduction state from the first terminal to the second terminal during operation of the power converter with the current detected in the first conduction state and a threshold voltage that changes according to the temperature detected in the first conduction state, or by comparing the voltage detected when both terminals are in a second conduction state from the second terminal to the first terminal with the current detected in the second conduction state and a threshold voltage that changes according to the temperature detected in the second conduction state. The current detection unit detects the load current of the power converter, The control unit determines, at least from the polarity of the load current, a first conduction state from the first terminal to the second terminal or a second conduction state from the second terminal to the first terminal. Power converter.

2. The aforementioned power semiconductor module includes power semiconductor elements, The temperature detection unit detects the temperature of the power semiconductor element, The control unit detects a potential failure or degradation of the power semiconductor element by comparing the voltage detected in the first conduction state from the first terminal to the second terminal with the current detected in the first conduction state and a threshold voltage that changes according to the temperature detected in the first conduction state. The power conversion device according to claim 1.

3. The control unit derives the threshold voltage by determining 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 of the power semiconductor element, and the voltage. The power conversion device according to claim 2.

4. The aforementioned power semiconductor module includes a diode, The temperature detection unit detects the temperature of the diode, The control unit detects a potential failure or deterioration of the diode by comparing the voltage detected in the second conduction state from the second terminal to the first terminal between the two terminals with the current detected in the second conduction state and a threshold voltage that changes according to the temperature detected in the second conduction state. The power conversion device according to claim 1.

5. The control unit derives the threshold voltage by determining the voltage corresponding to the current detected in the second conduction state and the temperature detected in the second conduction state, based on the relationship between the current, the temperature of the diode, and the voltage. The power conversion device according to claim 4.

6. A detection device for detecting signs of failure or degradation in a power semiconductor module having a first terminal and a second terminal, A voltage acquisition unit that acquires the voltage between the first terminal and the second terminal, A temperature acquisition unit that acquires the temperature of the power semiconductor module, A current acquisition unit that acquires the current flowing between the two terminals, The power converter, which converts power by driving the power semiconductor module, includes a detection unit that detects signs of failure or deterioration of the power semiconductor module by comparing the voltage detected when at least both terminals are in a first conduction state from the first terminal to the second terminal with the current detected in the first conduction state and a threshold voltage that changes according to the temperature detected in the first conduction state, or by comparing the voltage detected when both terminals are in a second conduction state from the second terminal to the first terminal with the current detected in the second conduction state and a threshold voltage that changes according to the temperature detected in the second conduction state. The current acquisition unit acquires the load current of the power converter, The detection unit determines, at least from the polarity of the load current, a first conduction state between the two terminals from the first terminal to the second terminal, or a second conduction state between the two terminals from the second terminal to the first terminal. Detection device.

7. The aforementioned power semiconductor module includes power semiconductor elements, The temperature acquisition unit acquires the temperature of the power semiconductor element, The detection unit detects a potential failure or degradation of the power semiconductor element by comparing the voltage detected in the first conduction state from the first terminal to the second terminal with the current detected in the first conduction state and a threshold voltage that changes according to the temperature detected in the first conduction state. The detection device according to claim 6.

8. The detection unit derives the threshold voltage by determining 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 of the power semiconductor element, and the voltage. The detection device according to claim 7.

9. The aforementioned power semiconductor module includes a diode, The temperature acquisition unit acquires the temperature of the diode, The detection unit detects a potential failure or deterioration of the diode by comparing the voltage detected in the second conduction state from the second terminal to the first terminal with the current detected in the second conduction state and a threshold voltage that changes according to the temperature detected in the second conduction state. The detection device according to claim 6.

10. The detection unit derives the threshold voltage by determining the voltage corresponding to the current detected in the second conduction state and the temperature detected in the second conduction state, based on the relationship between the current, the temperature of the diode, and the voltage. The detection device according to claim 9.

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