JP2008206217A - Semiconductor power converter having lifetime monitor circuit of semiconductor switching element - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a semiconductor power converter having a highly reliable lifetime monitor circuit of a semiconductor switching element which can predict the thermal cycle lifetime resulting from a thermal stress due to temperature ripple at the soldering portion of an IGBT chip and an FWD chip of the semiconductor switching element, and the power cycle lifetime resulting from a thermal stress due to temperature ripple at the bonding portion of the IGBT chip. <P>SOLUTION: The lifetime monitor circuit 20 has a memory circuit 16 for prestoring the relation of the output current and the number of times of lifetime for the power cycle lifetime and the thermal cycle lifetime of an IGBT chip 29 and an FWD chip 30, counts the number of repeating times of output current maximum value detected by a current detection circuit 31 and judges that a semiconductor switching element 6 has reached the lifetime when the count exceeds a reference value for trip determined based on the number of times of lifetime stored in the memory circuit 16. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a semiconductor power conversion device using a semiconductor switching element used for speed control of an electric motor, and more specifically, a semiconductor for preventing breakdown due to fatigue or deterioration due to energization of a semiconductor switching element and grasping a maintenance timing. The present invention relates to a semiconductor power conversion device having a switching element lifetime monitoring circuit.

  A conventional semiconductor power conversion device having a semiconductor switching element lifetime monitoring circuit measures the ripple temperature of the base plate temperature of the semiconductor switching element for each unit measurement period, and counts the number of occurrences for each ripple temperature for each unit measurement period. The lifetime is estimated according to the number of lifetimes for each temperature range with respect to the ripple temperature and the actual number of occurrences (for example, see Patent Document 1).

  In addition, the life cycle is estimated by obtaining the power cycle corresponding to the set value input as the junction temperature difference from the power cycle characteristics of the semiconductor switching device, and the estimated power cycle is multiplied by a coefficient less than 1 to the estimated life cycle of the semiconductor switching device. By setting the reference value, there are some that output a protection instruction signal when the number of operations of the device using the semiconductor switching element exceeds the reference value (see, for example, Patent Document 2).

  FIG. 3 is a configuration diagram of a semiconductor power conversion device having a life monitoring circuit of a semiconductor switching element showing the first prior art disclosed in Patent Document 1.

  In FIG. 3, 1 is an AC input power source, 3 is a rectifier circuit, 4 is a smoothing circuit, 5 is an inverter circuit, 7 is a motor, 11 is a drive circuit, 12 is an inverter control circuit, 21 is a temperature detection circuit, 22 is an A / A A D converter, 23 is a time measurement unit, 24 is a ripple temperature detection unit, 25 is a counter, 26 is a cumulative damage rate calculation unit, 27 is a lifetime calculation unit, and 28 is a control device.

  Hereinafter, the configuration and operation of the semiconductor power conversion apparatus having the semiconductor switching element lifetime monitoring circuit according to the first prior art will be described with reference to FIG.

  The main body of the semiconductor power conversion device is a motor that becomes a load by conversion into DC power by the rectifier circuit 3 and conversion from the DC power to AC power whose voltage and frequency are controlled by an inverter circuit 5 having a main circuit element as an IGBT. 7 is driven. The case where the control device 28 has a software configuration by a microprocessor is shown, and the life monitoring circuit 20 of the semiconductor switching element is provided by utilizing the information processing function. The life monitoring circuit 20 includes, as hardware, a temperature detection circuit 21 that measures the temperature by attaching a thermistor to a copper base plate that is a case of the IGBT module of the inverter circuit 5, and a temperature signal detected by the temperature detection circuit 21. Is converted to digital temperature data. As a software configuration of the life monitoring circuit 20, a time measurement unit 23, a ripple temperature detection unit 24, a counter 25, a cumulative damage rate calculation unit 26, and a life calculation unit 27 are provided as processing elements. The time measuring unit 23 extracts an operation pattern PT having time information of the operation time and the stop period from the operation / stop command of the semiconductor power conversion device. The ripple temperature detection unit 24 extracts the maximum temperature and the minimum temperature data within the unit measurement period from the operation pattern PT from the time measurement unit 23 and the temperature data from the A / D converter 22, and the ripple temperatures T1, T2, Calculated as T3,. Next, the counter 25 counts the number of occurrences of the ripple temperature during the unit measurement period. The cumulative damage rate calculator 26 estimates the lifetime of the IGBT from the number of occurrences n1, n2, n3,... And the known lifetime number data N1, N2, N3,.

  FIG. 4 is a configuration diagram of a semiconductor power conversion device having a life monitoring circuit of a semiconductor switching element showing the second prior art disclosed in Patent Document 2.

  In FIG. 4, 1 is an AC input power source, 2 is a semiconductor power converter, 3 is a rectifier circuit, 4 is a smoothing circuit, 5 is an inverter circuit, 6 is a semiconductor switching element, 7 is a motor, 8 is a rotational speed command value, 9 Is a switch as an operation commander, 9a is an operation command, 10 is a control circuit, 11 is a drive circuit, 12 is an inverter control circuit, 12a and 12b are reset signals, 13 and 14 are counters, 13a is an alarm signal, and 14a is a trip Reference numeral 15 is a reference value calculation circuit, 16 is a memory, 17 and 18 are coefficient setting input circuits, 19 is a junction temperature difference setting input circuit, 20 is a life monitoring circuit, 29 is an IGBT chip, and 30 is an FWD (flywheel) Diode) chip.

  Hereinafter, the configuration and operation of a semiconductor power conversion apparatus having a semiconductor switching element lifetime monitoring circuit according to the second prior art will be described with reference to FIG.

The semiconductor power conversion device 2 includes a rectifier circuit 3, a smoothing circuit 4, and an inverter circuit 5 as in the first prior art, and the inverter circuit 5 includes an appropriate number of semiconductor switching elements 6 such as power transistors and IGBTs. Yes. The control circuit 10 for the semiconductor power conversion device 2 includes a drive circuit 11 and an inverter control circuit 12. The inverter control circuit 12 receives a rotation speed command value 8 and an operation command 9 a through a switch 9 as an operation command device, and also receives an alarm signal 13 a and a trip signal 14 a from the life monitoring circuit 20. The life monitoring circuit 20 includes a counter 13 and a counter 14, a reference value calculation circuit 15, and a memory 16. Each time the operation command device 9 is turned on, an operation command 9 a is input to the counters 13 and 14. Coefficients K ₁ and K ₂ and set values of the junction temperature difference are input to the reference value calculation circuit 15, and reset signals 12 a and 12 b are input from the inverter control circuit 12. Reference values K ₁ C _P and K ₂ C _P are output from the reference value calculation circuit 15.

In the above configuration, the lifetime is estimated by obtaining the power cycle corresponding to the set value input as the junction temperature difference from the power cycle characteristics of the semiconductor switching device stored in the memory 16, and the estimated power cycle of the semiconductor switching device. reference value K ₁ C _P is multiplied by a coefficient K _1, K ₂ of less than 1 to C _P, and K ₂ C _P. Operating frequency of the semiconductor power conversion device using the same semiconductor switching elements, a reference value K ₁ C _P, and outputs a protection instruction signal when it exceeds K ₂ C _P.

  As described above, the semiconductor power conversion device having the life monitoring circuit of the semiconductor switching element according to the first conventional technique measures the ripple temperature of the base plate temperature of the main circuit element every unit measurement period, and calculates the number of occurrences for each ripple temperature. Counting is performed for each unit measurement period, and the lifetime is estimated according to the number of lifetimes for each temperature range relative to the ripple temperature and the actual number of occurrences.

Further, the semiconductor power conversion device having the semiconductor switching element life monitoring circuit according to the second prior art estimates the life by obtaining the power cycle corresponding to the set value inputted as the junction temperature difference from the power cycle characteristics of the semiconductor switching element. The power cycle estimated as the life of the semiconductor switching element is multiplied by a coefficient less than 1 to obtain a reference value. When the number of operations of the device using the semiconductor switching element exceeds the reference value, a protection instruction signal is output. Yes.
JP 2002-101668 A (FIG. 1) Japanese Patent Laid-Open No. 08-51768 (FIG. 1)

  However, the semiconductor power conversion device having the life monitoring circuit of the semiconductor switching element according to the first prior art measures the ripple temperature of the base plate temperature of the main circuit element, and therefore, due to the moderate temperature ripple of the solder part of the IGBT chip. Although the lifetime due to thermal stress can be predicted, there is a problem that the lifetime in which thermal stress is generated due to instantaneous temperature ripple at the bonding portion of the IGBT chip cannot be predicted. Further, there is a problem that the life of the solder part and the bonding part of the FWD chip cannot be predicted.

  In addition, the semiconductor power conversion device having the life monitoring circuit for the semiconductor switching element according to the second prior art has a problem that the life monitoring cannot be performed accurately because the current flowing through the semiconductor switching element is not measured.

  Here, the life of the semiconductor switching element will be described. During operation of the semiconductor power conversion device, a current flows, the semiconductor switching element generates heat, and the junction temperature of the IGBT chip and the FWD chip connected in parallel rises. On the other hand, when the semiconductor power converter is stopped, heat generation stops and the junction temperature decreases. For this reason, the IGBT chip and FWD chip portion of the semiconductor switching element repeats thermal expansion and thermal contraction due to repeated operation and stoppage. Since the semiconductor switching element is generally assembled using various materials having different thermal expansion coefficients, the solder portion and the bonding wire portion directly under the chip are particularly thermally deteriorated. The former is called the thermal cycle life, and the latter is called the power cycle life. In the former, a relatively slow and large temperature change caused by repeated operation and stoppage of the washing machine or the like causes a crack in the solder portion immediately below the chip, leading to thermal destruction. In the latter case, the bonding wire peels off due to the thermal expansion stress due to temperature change in an application such as an elevator, crane, machine tool, etc. where the frequency of operation and stop is high, resulting in failure or destruction. The IGBT chip and the FWD chip of the semiconductor switching element each have a thermal cycle life and a power cycle life.

  The present invention has been made in view of such problems, and is generated due to thermal cycle life caused by thermal stress generated by temperature ripple in the solder portion of the IGBT chip and FWD chip and by temperature ripple in the bonding portion of the IGBT chip. An object of the present invention is to provide a semiconductor power conversion device having a highly reliable semiconductor switching element life monitoring circuit capable of predicting a power cycle life caused by thermal stress.

  In order to solve the above problem, the present invention is configured as follows.

  The first aspect of the present invention includes a rectifying circuit that rectifies an AC input power source to convert it to DC, a smoothing circuit that smoothes the rectified DC, and at least one semiconductor switching element, the smoothed DC In the semiconductor power conversion device, comprising: an inverter circuit that converts a current into an arbitrary frequency; a current detection circuit that detects an output current of the inverter circuit; and a life monitoring circuit that monitors a life of the semiconductor switching element. The monitoring circuit has a first lifetime characteristic that is a relationship between the output current of the semiconductor switching element and the number of power cycle lifetimes, and a second lifetime characteristic that is a relationship between the output current of the semiconductor switching element and the number of thermal cycle lifetimes. A storage circuit stored in advance and a reference output of the semiconductor switching element based on the first and second life characteristics The number of power cycle lifetimes and the number of thermal cycle lifetimes during running are output as trip reference values, respectively, and the maximum output current is determined based on the maximum output current value detected by the current detection circuit and the first and second lifetime characteristics. A semiconductor switch history calculation circuit that converts and outputs the number of repetitions of the value to the number of repetitions at the reference output current, and a first counter that counts the converted number of repetitions, respectively, The life monitoring circuit is characterized by determining that the semiconductor switching element has reached the life when the count value of the first counter reaches one of the trip reference values.

  Moreover, in the semiconductor power conversion device having the life monitoring circuit for the semiconductor switching element according to claim 1, the life monitoring circuit determines that the semiconductor switching element has reached the life. In this case, a trip signal for stopping the operation of the semiconductor power converter is output.

  According to a third aspect of the present invention, in the semiconductor power conversion device having the life monitoring circuit of the semiconductor switching element according to the first aspect, the semiconductor switch history calculation circuit inputs an operation command to the semiconductor power conversion device. The accumulated accumulated time is measured and stored in the storage circuit as accumulated operating time, and the power cycle of the semiconductor switching element is based on the accumulated operating time, the count value of the first counter, and the trip reference value. The service life and the time to reach the thermal cycle life are predicted and output as maintenance time.

  According to a fourth aspect of the present invention, in the semiconductor power converter having the life monitoring circuit for the semiconductor switching element according to the first aspect, the semiconductor switch history calculation circuit is stored in the storage circuit. 1. Based on the second life characteristics, the alarm values of the power cycle life frequency and the thermal cycle life frequency at the reference output current of the semiconductor switching element are output as alarm reference values, respectively, and the life monitoring circuit A second counter is provided that counts the number of repeated times and outputs a warning signal when the counted value exceeds any one of the warning reference values.

  According to a fifth aspect of the present invention, in the semiconductor power converter having the semiconductor switching element life monitoring circuit according to the first or fourth aspect, the semiconductor switching element includes an IGBT chip and a flywheel diode chip. The first lifetime characteristic and the second lifetime characteristic both include the characteristics of the IGBT chip and the flywheel diode chip, respectively.

  According to a sixth aspect of the present invention, in the semiconductor power conversion device having the life monitoring circuit for the semiconductor switching element according to the fourth aspect, the semiconductor switch history calculation circuit inputs an operation command to the semiconductor power conversion device. The accumulated switching time is measured and stored as the accumulated operating time in the storage circuit, and the semiconductor switching element is connected to the power cycle based on the accumulated operating time, the count value of the second counter, and the alarm reference value. The service life and the time until reaching the alarm value of the thermal cycle life are predicted and output as maintenance time.

  According to a seventh aspect of the present invention, in the semiconductor power conversion device having the life monitoring circuit for the semiconductor switching element according to the third or sixth aspect, the life monitoring circuit includes a display unit for displaying the maintenance time. It is characterized by that.

  According to the first aspect of the present invention, the thermal cycle life caused by the gentle temperature ripple of the solder portion immediately below the chip of the semiconductor switching element and the thermal stress caused by the instantaneous temperature ripple of the bonding portion of the chip are caused. A power cycle life can be predicted, and a semiconductor power conversion device having a highly reliable semiconductor switching element life monitoring circuit can be obtained.

  Further, according to the invention of claim 2, by using a trip signal, the operation of the semiconductor power conversion device using the element can be stopped and replaced with a new one before destruction of the semiconductor switching element. A semiconductor power converter having a highly reliable semiconductor switching element life monitoring circuit can be obtained.

  Further, according to the invention described in claim 3, since the time until the trip due to the thermal cycle life and the power cycle life is known, the same element should be replaced with a new one in advance by using the time until the lifetime is reached. A plan for a maintenance period can be made, and a semiconductor power conversion device having a highly reliable semiconductor switching element lifetime monitoring circuit can be obtained.

  According to the invention described in claim 4, by using an alarm signal, it is determined that the same element must be replaced with a new one before destruction of the semiconductor switching element, or a device using the element. It is possible to stop the operation of the element and prevent the destruction of the element, and a more reliable semiconductor power conversion device can be obtained.

  According to the invention described in claim 5, the thermal cycle life and the moment of bonding of the chip due to the thermal stress caused by the gradual temperature ripple of the solder part immediately below the chip of the semiconductor switching element for each IGBT chip and FWD chip. Therefore, it is possible to predict a power cycle life caused by thermal stress due to a typical temperature ripple, and to obtain a semiconductor power conversion device having a highly reliable semiconductor switching element life monitoring circuit.

  Further, according to the invention described in claim 6, since the time until the alarm of the thermal cycle life and the power cycle life is reached is known, the same element is replaced with a new one in advance by using the time until the alarm is reached. A plan for the time of maintenance to be performed can be made, and a semiconductor power conversion device having a semiconductor switching element life monitoring circuit with higher reliability can be obtained.

  Further, according to the invention described in claim 7, since the time until the thermal cycle life and the power cycle life are reached can be easily determined by the display unit, the same element can be obtained in advance by using the time until the life is reached. A plan for a maintenance period to be replaced with a new one can be made, and a semiconductor power conversion device having a highly reliable semiconductor switching element life monitoring circuit can be obtained.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

  FIG. 1 is a configuration diagram of a semiconductor power conversion device having a life monitoring circuit for a semiconductor switching element according to the present invention.

In FIG. 1, 1 is an AC input power source, 2 is a semiconductor power converter, 3 is a rectifier circuit that rectifies and converts the AC input power source into DC, 4 is a smoothing circuit that smoothes the rectified DC, and 5 is a semiconductor switching element. Inverter circuit for converting DC to any frequency, 6 is a semiconductor switching element comprising IGBT chip and FWD chip, 7 is a motor, 8 is a rotational speed command value, 9 is an operation command device Switch, 9a is an operation command, 10 is a control circuit, 11 is a drive circuit, 12 is an inverter control circuit, 12a and 12b are reset signals, 13 and 14 are counters, 13a is an alarm signal, 14a is a trip signal, 16 is a memory circuit , 17 and 18 are coefficient setting input circuits, 20 is a life monitoring circuit, 29 is an IGBT chip, 30 is an FWD chip, and 31 is Current detecting circuit for detecting a force current, 32 denotes a semiconductor switching history calculation circuit, 33 is the maintenance time. K ₁ and K ₂ are coefficients, PC is an abbreviation for power cycle, and TC is an abbreviation for thermal cycle.

  The present invention is different from the prior art in that the life monitoring circuit 20 in the semiconductor power conversion device 2 according to the present invention has a first life characteristic and a semiconductor switching which are the relationship between the output current of the semiconductor switching element 6 and the number of power cycle lives. A memory circuit 16 that stores in advance a second life characteristic that is a relationship between the output current of the element 6 and the number of times of thermal cycle life, and a reference output current of the semiconductor switching element 6 based on the first and second life characteristics. The power cycle life count and thermal cycle life count are output as trip reference values, respectively, and the output current maximum value detected by the current detection circuit 31 and the number of repetitions of the output current maximum value based on the first and second life characteristics. A semiconductor switch history calculation circuit 32 for converting the output into the number of repetitions at the time of the reference output current, A first counter 14 for counting the calculated number of repetitions, and the life monitoring circuit 20 includes a semiconductor switching element when the count value of the first counter 14 reaches one of the trip reference values. 6 is determined to have reached the end of its life.

  Hereinafter, the overall configuration and operation of the semiconductor power conversion apparatus having the life monitoring circuit 20 of the semiconductor switching element of this embodiment will be described with reference to FIG.

  For example, commercial three-phase alternating current is input from the AC input power source 1 and converted into DC power by the rectifier circuit 3 and the smoothing circuit 4. The DC power is switched by the IGBT chip 29 in the inverter circuit 5, for example, predetermined three-phase. The frequency is converted into alternating current and given to the motor 7. As a result, the motor 7 is driven at a rotational speed corresponding to the frequency of the AC power supplied from the inverter circuit 5.

  The control circuit 10 includes a drive circuit 11 and an inverter control circuit 12. The inverter control circuit 12 receives not only the rotation speed command value 8 and the operation command 9a through the switch 9 as an operation command device, but also an alarm signal 13a from the counter 13 of the life monitoring circuit 20 described later. A trip signal 14 a is input from the counter 14 of the life monitoring circuit 20. The inverter control circuit 12 outputs reset signals 12a and 12b as control signals to the counters 13 and 14 of the life monitoring circuit 20 as will be described later.

  As the operation of the control circuit 10, while the switch 9 is on, each semiconductor switching required for the inverter circuit 5 to generate AC power having a frequency corresponding to the rotational speed command value 8 from the current value detected by the current detection circuit 31. A timing control signal for turning on / off the element 6 is generated by the inverter control circuit 12 in accordance with the rotational speed command value 8, and this timing control signal is necessary for the semiconductor switching element 6 to be turned on / off. The drive circuit 11 is amplified to the level, and the semiconductor switching element 6 is turned on / off. That is, while the switch 9 is on, the semiconductor power conversion device 2 is in an operating state and the motor 7 rotates. However, when the trip signal 14a is input even when the switch 9 is on, the inverter control circuit 12 generates a control signal for turning off all the semiconductor switch elements 6, and forcibly activates the semiconductor power conversion device 2. Stop. When the alarm signal 13a is input, the inverter control circuit 12 activates an alarm device (not shown), informs the staff that it is time to maintain the semiconductor switching element 6, and replaces it with a new one. Prompt. When the semiconductor switching element 6 is replaced with a new one, a staff member inputs a reset switch or the like (not shown) to output reset signals 12a and 12b from the inverter control circuit 12 to the life monitoring circuit 20.

  While the switch 9 is off, the inverter control circuit 12 generates a control signal that turns off all the semiconductor switching elements 6 in the inverter circuit 5. That is, when the switch 9 is off, the semiconductor power conversion device 2 is stopped and the motor 7 is stopped.

  2A and 2B are examples of life characteristics stored in the memory 16 in this embodiment. FIG. 2A is an example of thermal cycle life characteristics, and FIG. 2B is an example of power cycle life characteristics. The number of times and the horizontal axis represent the output current of the semiconductor switching element 6.

  Hereinafter, the detailed configuration and operation of the lifetime monitoring circuit 20 of the semiconductor switching element in the semiconductor power conversion device of this embodiment will be described with reference to FIGS.

  The life monitoring circuit 20 converts the number of repetitions of the maximum value of the output current flowing when the motor 7 is detected from the memory 16 and the current detection circuit 31 to the number of times of life at the reference output current of the semiconductor switching element 6. And a semiconductor switch history calculation circuit 32 for calculating the energization history by integrating these, and the counter 13 and the counter 14.

  In the memory 16, thermal cycle life characteristics and power cycle life characteristics for each of the IGBT chip 29 and the FWD chip 30 of the power switching element 6 used in the power conversion device 2, that is, output current and life as shown in FIG. The correlation with the number of times is stored in the form of a table in advance.

The semiconductor switch history calculation circuit 32 is a semiconductor based on the thermal cycle life characteristic and power cycle life characteristic of the semiconductor switching element in which the number of times the maximum output current value detected from the current detection circuit 31 is repeatedly input is stored in the memory 16. It is converted into the number of repetitions at the time of the reference output current of the switching element and given to the counter 13 and the counter 14 respectively. Further, when the coefficient K ₁ (0 <K ₁ <1) is set by the coefficient setting input circuit 17, the semiconductor switch history calculation circuit 32 stores the IGBT chip 29 and the FWD chip 30 stored in advance in the storage circuit 16. Based on the power cycle life characteristics and the thermal cycle life characteristics, the number of power cycle lives and the number of thermal cycle lives of the IGBT chip 29 and the FWD chip 30 at the reference output current of the semiconductor switching element are obtained, and the coefficient K ₁ And the value is given to the counter 13 as a warning reference value. Similarly, when the coefficient K ₂ (K ₁ <K ₂ <1) is set by the coefficient setting input circuit 18, the number of times of each life is multiplied by the coefficient K ₂ , and the value is used as a trip reference value. To give.

  The counter 13 is of a count-up type, and the reference values for alarms of the power cycle life and the thermal cycle life of the IGBT chip 29 and the FWD chip 30 given from the semiconductor switch history calculation circuit 32 are set values, The number of times the maximum output current value detected from the detection circuit 31 is repeatedly input, that is, the number of power cycles and the number of thermal cycles converted at the reference output current of the IGBT chip 29 and the FWD chip 30, is counted, and the count value increases. When any of the alarm reference values is exceeded, the alarm signal 13a is output to the inverter control circuit 12 and the outside. When the counter 13 receives the reset signal 12a from the inverter control circuit 12, the counter 13 stops outputting the alarm signal 13a and simultaneously returns the count value to zero.

  The counter 14 is of a count-up type like the counter 13 and sets reference values for tripping of the power cycle life and the thermal cycle life of the IGBT chip 29 and the FWD chip 30 given from the semiconductor switch history calculation circuit 32. The number of times the maximum output current value detected from the current detection circuit 31 is repeatedly input, that is, the number of power cycles and the number of thermal cycles converted to the reference output current of the IGBT chip 29 and the FWD chip 30, is counted. When the value increases and exceeds any of the trip reference values, the trip signal 14a is output to the inverter control circuit 12 and the outside. When the reset signal 12b is input from the inverter control circuit 12, the counter 14 stops outputting the trip signal 14a and simultaneously returns the count value to zero.

  Further, the semiconductor switch history calculation circuit 32 obtains a value obtained by dividing the cumulative operation time stored in the memory 16 by the count value of the counter 13 until an alarm obtained by subtracting the count value of the counter 13 from the reference value for alarm. By multiplying the remaining number of times, the maintenance time 33 until the alarm of the power cycle life and the thermal cycle life of the IGBT chip 29 and the FWD chip 30 is predicted, respectively, and the semiconductor switching element 6 is maintained by a display (not shown). Inform the staff that the time has come, and encourage them to replace it with a new one. Further, the value obtained by dividing the accumulated operation time stored in the memory 16 by the count value of the counter 14 is a value obtained by subtracting the count value of the counter 14 from the trip reference value for each of the IGBT chip 29 and the FWD chip 30. By multiplying the number of remaining lifetimes, the maintenance time 33 until the trip signal due to the power cycle lifetime and the thermal cycle lifetime of the IGBT chip 29 and the FWD chip 30 is predicted, respectively, and the semiconductor switching element 6 is displayed by a display (not shown). Inform the staff that it is time to maintain the product and encourage replacement.

  As described above, the semiconductor power conversion device 2 having the life monitoring circuit 20 of the semiconductor switching element 6 according to the present embodiment stores in advance the thermal cycle life characteristics and power cycle life characteristics of the IGBT chip 29 and the FWD chip 30, respectively. The storage circuit 16 is provided, the number of repetitions of the maximum output current value detected by the current detection circuit 31 is counted, and the calculated value is calculated from the thermal cycle life characteristics and power cycle life characteristics stored in the storage circuit 16. Since it is determined that the semiconductor switching element 6 has reached the end of its life based on exceeding the trip reference value, which is the number of trips, it is caused by thermal stress due to instantaneous temperature ripple in the bonding portion of the IGBT chip 29. Power cycle life can also be predicted, and solder of FWD chip 30 It can also be predicted thermal cycle life and the bonding portion of the power cycle life. Further, the maximum value of the output current flowing through the semiconductor switching element 6 when the motor 7 is started and stopped is measured by the current detection circuit 31, and the semiconductor switching element 6 is measured based on the stored power cycle life characteristics and thermal cycle life characteristics. Since the life is predicted by converting the number of repetitions at the reference output current, accurate life monitoring can be performed.

  INDUSTRIAL APPLICABILITY The present invention can be applied to a semiconductor power conversion device used for applications such as washing machines, elevators, cranes, and machine tools that perform repeated operations, and in particular, semiconductor power conversion for servo drivers, inverter devices, etc. in applications that require reliability. Suitable for the device.

1 is a block diagram of a semiconductor power conversion apparatus having a life monitoring circuit for a semiconductor switching element according to the present invention. Examples of thermal cycle life characteristics and power cycle life characteristics stored in the memory 16 in this embodiment 1 is a configuration diagram of a semiconductor power conversion device having a life monitoring circuit of a semiconductor switching element showing a first prior art. The block diagram of the semiconductor power converter device which has the lifetime monitoring circuit of the semiconductor switching element which shows 2nd prior art

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 AC input power source 2 Semiconductor power converter 3 Rectifier circuit 4 Smoothing circuit 5 Inverter circuit 6 Semiconductor switching element 7 Motor 8 Rotational speed command value 9 Operation command device (switch)
9a Operation command 10 Control circuit 11 Drive circuit 12 Inverter control circuit 12a, 12b Reset signal 13, 14, 25 Counter 13a Alarm signal 14a Trip signal 15 Reference value calculation circuit 16 Memory (storage circuit)
17, 18 Coefficient setting input circuit 19 Junction temperature difference setting input circuit 20 Life monitoring circuit 21 Temperature detection circuit 22 A / D converter 23 Time measurement unit 24 Ripple temperature detection unit 26 Cumulative damage rate calculation unit 27 Life calculation unit 28 Control device 29 IGBT chip 30 FWD chip 31 Current detection circuit 32 Semiconductor switch history calculation circuit 33 Maintenance time

Claims (7)

A rectifier circuit (3) for rectifying the AC input power supply (1) and converting it to DC;
A smoothing circuit (4) for smoothing the rectified direct current;
An inverter circuit (5) comprising at least one semiconductor switching element (6) and converting the smoothed direct current into an arbitrary frequency;
A current detection circuit (31) for detecting an output current of the inverter circuit (5);
A life monitoring circuit (20) for monitoring the life of the semiconductor switching element (6);
In the semiconductor power conversion device (2) provided with
The life monitoring circuit (20)
A first lifetime characteristic that is a relationship between the output current of the semiconductor switching element (6) and the number of power cycle lifetimes, and a second lifetime that is a relationship between the output current of the semiconductor switching element (6) and the number of thermal cycle lifetimes. A storage circuit (16) pre-stored with characteristics;
Based on the first and second lifetime characteristics, the number of power cycle lifetimes and the number of thermal cycle lifetimes at the time of the reference output current of the semiconductor switching element (6) are output as trip reference values, respectively, and the current detection circuit (31 Semiconductor switch history for converting the number of repetitions of the maximum output current value into the number of repetitions at the reference output current based on the maximum output current value detected in step (1) and the first and second life characteristics. An arithmetic circuit (32);
A first counter (14) for counting the converted number of repetitions, respectively.
The life monitoring circuit (20) determines that the semiconductor switching element (6) has reached the end of life when the count value of the first counter (14) reaches any of the trip reference values. A semiconductor power conversion device having a life monitoring circuit for a semiconductor switching element. The life monitoring circuit (20)
2. The semiconductor according to claim 1, wherein a trip signal (14 a) for stopping the operation of the semiconductor power conversion device (2) is output when it is determined that the semiconductor switching element (6) has reached the end of its life. A semiconductor power conversion device having a switching element lifetime monitoring circuit. The semiconductor switch history calculation circuit (32)
The accumulated time during which the operation command (9a) is input to the semiconductor power conversion device (2) is measured and stored in the storage circuit (16) as the accumulated operating time, and the accumulated operating time, the first counter ( 14) predicting the time until the power cycle life and the thermal cycle life of the semiconductor switching element (6) are reached based on the count value of 14) and the trip reference value, and outputting the predicted time as a maintenance time. The semiconductor power converter device which has a lifetime monitoring circuit of the semiconductor switching element of Claim 1. The semiconductor switch history calculation circuit (32) has a power cycle life at a reference output current of the semiconductor switching element (6) based on the first and second life characteristics stored in the memory circuit (16). The alarm value of the number of times and the number of times of thermal cycle life is output as the alarm reference value.
The life monitoring circuit (20) counts the converted number of repetitions and outputs a second counter (13) that outputs an alarm signal (13a) when the counted value exceeds any one of the alarm reference values. The semiconductor power converter device which has the lifetime monitoring circuit of the semiconductor switching element of Claim 1 provided.   The semiconductor switching element (6) includes an IGBT chip (29) and a flywheel diode chip (30), and both the first life characteristic and the second life characteristic are the same as the IGBT chip (29). 5. The semiconductor power conversion device having a semiconductor switching element life monitoring circuit according to claim 1, wherein the semiconductor power conversion device includes the characteristics of the flywheel diode chip (30). The semiconductor switch history calculation circuit (32)
The accumulated time during which the operation command (9a) is input to the semiconductor power conversion device (2) is measured and stored in the storage circuit (16) as the accumulated operation time, and the accumulated operation time, the second counter ( 13) Predicting the time until the semiconductor switching element (6) reaches the alarm value of the power cycle life and the thermal cycle life based on the count value of 13) and the reference value for alarm, and outputting as a maintenance time A semiconductor power conversion device comprising a semiconductor switching element life monitoring circuit according to claim 4. The life monitoring circuit (20)
7. The semiconductor power conversion apparatus having a semiconductor switching element life monitoring circuit according to claim 3, further comprising a display unit for displaying the maintenance time.

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