JP2004080865A - Failure diagnostic circuit for semiconductor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a abnormality diagnostic circuit for semiconductors, capable of detecting whether there is an OFF permanent fault in IGBTs connected in parallel, even while reducing the number of comparison circuits for failure diagnosis. <P>SOLUTION: In a module of an inverter, used with the plurality of IGBTs connected in parallel, the IGBTs connected in parallel are formed with the IGBT3 and temperature-detecting diodes 4 on the same semiconductor substrate 2. The plurality of temperature detecting diodes 4 are divided into at least two pairs connected in series, to supply current to the temperature detecting diodes 4, of which each pair is connected in series from a constant-current circuit 5, detect the difference in voltage drop, in each pair connected in series by a differential circuit 6; and if the difference voltage is in excess of a prescribed voltage, it determines that either of the IGBT2 is abnormal, and transmits a signal. <P>COPYRIGHT: (C)2004,JPO

Description

ここで、
Ｖ^＊：　インバータの通常運用時の想定最高温度に対する温度検出用ダイオード４の電圧降下
【００２０】
図３は、本実施例においてＣＰＵ１１が実行する異常診断ロジックを示す。
ＣＰＵ１１は比較異常検知回路１２からのＳ２、および上述のＳ３、Ｓ４の信号の有無によって以下のように異常診断を行う。
まず、ステップ１０１では、比較異常検知回路１２において２組の温度検出用ダイオード４ａ、４ｂと４ｃ、４ｄの直列出力電圧和の間に閾値Ｖ_{ｒｅｆ＿ｄｉｆｆ}を越えた差がある場合に出力されるＳ２信号の有無によって比較異常の可能性があるかどうかを判断する。閾値を越えた差がなければステップ１０２に進み、閾値を越えた差の場合はステップ１０４に進む。
ステップ１０２では、温度検出用ダイオード４ｃ、４ｄの直列出力電圧和がＶ_{ｒｅｆ１’}を下回って、過温度検知回路１３から温度高警報信号Ｓ３が出ていないか確認する。Ｓ３信号が出ていない場合にはステップ１０３に進む。Ｓ３信号が出ている場合にはステップ１０７へ進む。
ステップ１０３では、ＩＧＢＴは全て正常と判断されて、正常状態を示す「正常」灯、例えば緑灯を点灯する。
【００２１】
ステップ１０４では、温度検出用ダイオード４ｃ、４ｄの直列出力電圧和がＶ_{ｒｅｆ１’}を下回って、過温度検知回路１３から温度高警報信号Ｓ３が出ていないか確認する。Ｓ３信号が出ていない場合にはステップ１０５に進む。Ｓ３信号が出ている場合にはステップ１０７へ進む。
ステップ１０５では、ＩＧＢＴのいずれかがＯＦＦ固定故障の可能性があるとして、インバータ出力を５０％に制限する出力信号を出して、ステップ１０６に進む。
ステップ１０６では、ＩＧＢＴは過温度状態ではないと判断されて、比較異常状態を示す「比較異常警報」灯、例えば黄灯を点灯する。
【００２２】
ステップ１０７では、温度検出用ダイオード４ｃ、４ｄの直列出力電圧和がＶ_{ｒｅｆ２’}を下回って、過温度検知回路１３から温度高高警報信号Ｓ４が出ていないか確認する。Ｓ４信号が出ていない場合にはステップ１０８に進む。Ｓ４信号が出ている場合にはステップ１１０へ進む。
ステップ１０８では、ＩＧＢＴは過温度状態ではあるがモータ駆動を停止する必要はない第１段階の過温度異常状態であると判断して、インバータ出力を５０％に制限する出力信号を出す。
ステップ１０９では、過温度異常の第１段階状態を示す「温度高警報」灯、例えば赤灯を１つ点灯する。
【００２３】
ステップ１１０では、ＩＧＢＴは過温度状態が機器破損の可能性がある第２段階の過温度状態であると判断して、インバータ出力を停止する。
ステップ１１１では、過温度異常の第２段階状態を示す「温度高高警報」灯、例えば赤灯を２つ点灯する。
【００２４】
本実施例におけるＩＧＢＴ３は本発明の半導体素子に、差分回路６は差分演算手段に、比較回路８は異常検知手段に対応する。
【００２５】
本実施例は以上のように構成され、第１の実施例と同じく、並列接続された複数のＩＧＢＴに対応して設けられた温度検出用ダイオードを２組に分け、それぞれの組の温度検出用ダイオードの直列出力電圧和を比較し、直列出力電圧和の差が閾値Ｖ_{ｒｅｆ＿ｄｉｆｆ}を越えたときに異常であると判断しているので、インバータの出力レベルによって、またインバータの環境状況によってＩＧＢＴの温度が変化するにもかかわらず、ＩＧＢＴ間の温度差を検出できる。
また、同一組内のＩＧＢＴが同一方向に異常な兆候を示している場合、温度検出用ダイオードを直列に接続し、その直列電圧を用いていることから、Ｓ／Ｎが改善され、診断の信頼性が向上する。
さらに、温度検出用ダイオードを直列接続し、その直列された温度検出用ダイオードの電圧を比較する構成のため、比較回路の数を削減でき、簡単な診断回路を実現できている。
【００２６】
本実施例では、さらに各少なくとも１組の直列された温度検出用ダイオードの直列出力電圧和を過温度検知回路によって判定しているので、各組のＩＧＢＴが同時に過温度異常を生じている場合に比較異常検知回路１２で異常を検知できなくても、過温度検知回路１３によって異常を検知できる。
この過温度検知回路１３も直列接続された温度検出用ダイオードの少なくとも１つの組に対して１個設けるようにしていることから従来のようなＩＧＢＴ１個に対して１個の過温度検知回路を設けるよりも回路の数を大幅に削減でき、簡単な診断回路によって実現できている。
【００２７】
同一製造ロットのＩＧＢＴで並列に接続されている複数のＩＧＢＴの１個が故障して過電流になっている場合、他のＩＧＢＴも同時に同じ故障をしている可能性が高いことから、本実施例においては比較異常回路で比較されている直列接続された温度検出用ダイオードの直列出力電圧和のうちの一方の直列出力電圧和だけを過温度検知回路１３で判定する簡略化した構成としている。
その場合、過温度検知回路１３の基準電圧Ｖ_{ｒｅｆ１’}とＶ_{ｒｅｆ２’}を（２）、（３）式の代わりに次式のように簡略化してもよい。
Ｖ_{ｒｅｆ１’}＝Ｖ_ｒｅｆ１×ｎ　　　　　…（２’）
Ｖ_{ｒｅｆ２’}＝Ｖ_ｒｅｆ２×ｎ　　　　　…（３’）
【００２８】
以上の本発明の実施例では、半導体素子としてＩＧＢＴを例に挙げて説明したが、半導体素子はＩＧＢＴに限定されず、例えばトランジスタ、ＳＣＲ、ダイオードなどであってもよい。さらに、１個の半導体素子（ＩＧＢＴ）を内蔵する半導体基板を例に挙げて説明したが、２個以上の半導体素子を内蔵する半導体基板に対しても本願発明を適用することができる。
【００２９】
【図面の簡単な説明】
【図１】本発明の第１の実施例の異常診断回路の構成を示す図である。
【図２】第２の実施例の構成を示す図である。
【図３】第２の実施例の異常診断ロジックを説明する図である。
【符号の説明】
１　半導体モジュール
２、２ａ〜２ｄ　半導体基板
３、３ａ〜３ｄ　ＩＧＢＴ
４、４ａ〜４ｄ　温度検出用ダイオード
５　定電流回路
６　差分回路
７、７’　基準電圧回路
８、８’　比較回路
９、９’　比較回路
１１　　　ＣＰＵ
１２　　　比較異常検知回路
１３　　　過温度検知回路
１４、１４’　　基準電圧回路
Ｓ１　　　ＩＧＢＴ駆動信号
Ｓ２　　　比較異常信号
Ｓ３　　　温度高警報信号
Ｓ４　　　温度高高警報信号[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a semiconductor element abnormality diagnosis circuit that detects an abnormality of a semiconductor module.
[0002]
[Prior art]
In a semiconductor module containing a plurality of semiconductor substrates on each of which a semiconductor element and a temperature detection diode of the semiconductor element are integrated, a plurality of temperature detection diodes are used to detect a temperature abnormality of the semiconductor element based on a forward current voltage. Connect in series, supply a constant current from one constant current circuit to each temperature detection diode, and compare the voltage across both ends of each temperature detection diode with the reference voltage power supply that generates the reference voltage. There is known a temperature detecting device in which a circuit in which a comparison circuit is connected in series is connected in parallel with each of the temperature detecting diodes (for example, see Japanese Patent Application Laid-Open No. 2002-107232).
[0003]
[Problems to be solved by the invention]
By the way, when the temperature detection circuit of a plurality of semiconductor elements and its power supply are integrated to reduce the size, the above-described known temperature detection device includes a comparison circuit that compares the output voltage of the temperature detection diode with a reference voltage. It is necessary to prepare as many as the number of semiconductor elements, and there is a problem that the area of the semiconductor substrate increases and the number of temperature abnormality detection wirings increases.
Also, when applied to a plurality of insulated gate bipolar transistors (IGBTs) connected in parallel, the current value of the IGBT is below the allowable value even if any one of the IGBTs becomes an OFF-fixed fault due to a terminal open fault or the like. As long as the remaining IGBTs disperse and bear the current, they are buried in the margin of heat dissipation design and cannot detect abnormalities, and thermal stress more than expected at the time of design concentrates on the semiconductor element substrate other than the fault. Secondary failures such as cracks and the like are likely to occur and the life of the equipment may be shortened. In order to accurately detect a state in which one of the plurality of IGBTs has become an OFF fixed failure, the IGBTs are individually turned on, and the detection temperatures of the temperature detection diodes corresponding to the respective semiconductor substrates increase. It was necessary to use a special abnormality diagnosis sequence and circuit, such as confirming that it was correct.
[0004]
SUMMARY OF THE INVENTION An object of the present invention is to provide a semiconductor abnormality diagnosis circuit capable of detecting an OFF fixed failure of any semiconductor element connected in parallel with a simple circuit and method in order to solve the above problems.
[0005]
[Means for Solving the Problems]
Therefore, the present invention provides a semiconductor abnormality diagnosis circuit for detecting an abnormality of a semiconductor module including a plurality of semiconductor elements and a temperature detection diode for detecting the temperature thereof, wherein the temperature detection diodes are divided into at least two sets. The temperature detecting diodes included in each set are connected in series, a constant current is supplied from a constant current circuit to the temperature detecting diodes connected in series, and the temperature detecting diodes of each set are connected in series. It is provided with a difference calculating means for calculating a difference between the output voltage sums, and an abnormality detecting means for detecting a case where the difference output from the difference calculating means is equal to or more than a predetermined value and generating a signal.
[0006]
【The invention's effect】
According to the present invention, the same number of temperature detecting diodes of a plurality of semiconductor elements are put together into a set, the temperature detecting diodes of each set are connected in series, and the output voltage sum is compared between the sets. If any one of the semiconductor elements included in the group has an abnormality, it can be detected by a difference of a predetermined value or more in the sum of the output voltages of the temperature detecting diodes of each group. In particular, in a configuration in which semiconductor elements are connected in parallel, even when one semiconductor element has an OFF-fixed failure, an abnormality can be detected without providing a semiconductor element switching test circuit.
[0007]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, a first example of the embodiment of the present invention will be described. FIG. 1 shows an IGBT power module circuit for one phase of an IGBT power module circuit used for an inverter of a three-phase synchronous motor used in an electric vehicle, and shows a plurality of IGBTs connected in parallel and an abnormality diagnosis circuit thereof.
In this embodiment, four IGBTs 3 (3a to 3d) are connected in parallel and controlled by one drive signal S1 in order to cope with a required large current. The IGBTs 3 (3a to 3d) and the temperature detecting diodes 4 (4a to 4d) are formed and built on the same semiconductor substrate 2 (2a to 2d). For example, in the semiconductor substrate 2a, the IGBT 3a and the temperature detecting diode 4a are formed on the same semiconductor substrate and are built therein. The same applies to the other semiconductor substrates 2b, 2c, 2d.
[0008]
The temperature detecting diodes 4a and 4b are connected in series, the temperature detecting diodes 4c and 4d are also connected in series, and a constant current is supplied from an individual constant current circuit 5 to each pair connected in series. The respective series output voltages are connected to the minus terminal and the plus terminal of the difference circuit 6.
The output of the difference circuit 6 is connected to the comparison circuits 8 and 8 ', and is used to determine whether the difference voltage output from the difference circuit 6 is greater than or equal to a predetermined voltage difference V _{ref_diff regardless} of whether the difference voltage is positive or negative. Circuits 8 and 8 'are connected to reference voltage circuits 7 and 7', respectively.
The comparison circuits 8 and 8 'output a comparison abnormality signal S2 to the CPU 11 when the voltage difference is equal to or larger than a predetermined voltage difference.
[0009]
Hereinafter, a method of setting the reference voltage _{Vref_diff} for comparing the input voltages of the difference circuit 6, which is a feature of the present embodiment, will be described.
Here, the four IGBTs 3a to 3d connected in parallel as shown in FIG. 1 are of the same production lot and have the same characteristics such as gate input capacitance and ON voltage. Are designed so that the current values flowing through the IGBTs are the same.
Further, the temperature detection diodes 4a to 4b of the respective IGBTs are also of the same production lot, and when the same level of forward current IF flows, the temperature detection diodes 4a to 4b are the same under the same temperature environment. The characteristic values are arranged so as to generate a voltage drop VF. The temperature dependency of the voltage drop due to the forward current of the temperature detecting diode 4 is about -2 mV / ° C.
[0010]
Further, the semiconductor substrates 2a to 2d of the IGBTs 3a to 3d connected in parallel are arranged so that the heat dissipation structure is the same, and when the same current loss occurs in each of the IGBTs 3a to 3d, The substrate temperature is designed to be the same.
[0011]
As described above, the IGBTs 3a to 3d and the temperature detecting diodes 4a to 4d are designed so that their characteristic values are the same including the heat radiation conditions. , All the voltage drops VF of the temperature detecting diodes 4a to 4d show the same value.
Therefore, the temperature detection diodes 4 provided on the semiconductor substrate 2 of the plurality of IGBTs 3 connected in parallel as shown in FIG. 1 are divided into two sets, and the temperature detection diodes 4a and 4b are used for the temperature detection as well. Even if the sum of the voltage drops of the diodes 4c and 4d is compared, there is no difference in principle as long as the diodes are used in a normal state.
[0012]
Actually, even in the case of IGBTs of the same manufacturing lot and temperature detecting diodes of the same manufacturing lot, there are manufacturing variations in the characteristic values between the individual IGBTs and between the individual temperature detecting diodes, and furthermore, the heat dissipation structure of the semiconductor module. In the same manner, a variation in manufacturing and a spatial distribution of heat radiation capability are generated. As a result, there is a slight difference when comparing the sum of the voltage drops of the two sets of temperature detecting diodes connected in series. The threshold value _{Vref_diff} is set by taking into account the difference due to the manufacturing variation and adding a margin to the voltage difference that can be obtained due to the manufacturing variation.
Specifically, the voltage difference per one diode for temperature detection assumed by the variation of the characteristic value is ΔV1, the voltage difference per diode assumed by the variation of the mounting is ΔV2, and the temperature obtained by taking the sum of the output voltages When the number of detection diodes is n and the margin ratio is Cm,
_{Vref_diff} = (ΔV1 + ΔV2) × n × Cm (1)
It becomes.
[0013]
Next, in this embodiment, when any one of the plurality of IGBTs 3a to 3d connected in parallel has a fixed OFF fault due to a short-circuit fault between a gate and an emitter terminal, an open fault at a collector or an emitter terminal, or the like. The operation of the semiconductor abnormality diagnosis circuit will be described.
When such a failure occurs, the specified current does not flow between the collector and the emitter terminal of the failed IGBT, so that no current loss occurs, and the semiconductor substrate temperature is lower than other normal IGBTs. Become. Therefore, the voltage drop of the temperature detecting diode on the same semiconductor substrate is larger than the voltage drops of the temperature detecting diodes of other normal IGBTs.
[0014]
As a result, of the sum of the voltage drops of the temperature detecting diodes divided into two sets, that is, the sum of the series output voltages, the sum of the series output voltages on the side including the failed IGBT becomes larger, and the two sets of the series output voltages If the difference between the sums exceeds the above-described threshold value _{Vref_diff} , the comparison circuit 8 or 8 'outputs a comparison abnormality signal S2 to the CPU 11.
When receiving the comparison abnormality signal S2, the CPU 11 limits the output of the inverter to, for example, 50% and turns on a "comparison abnormality warning" lamp, for example, a yellow lamp to notify the driver.
[0015]
The IGBT 3 of this embodiment constitutes the semiconductor element of the present invention, the difference circuit 6 constitutes a difference calculation means, and the comparison circuits 8 and 8 'constitute abnormality detection means.
[0016]
In this embodiment, the temperature detecting diodes provided for the plurality of IGBTs connected in parallel are divided into two groups, and the series output voltage sums of the temperature detecting diodes of each group are compared. However, since the abnormality is determined when the difference between the series output voltage sums exceeds the threshold value _{Vref_diff} , the temperature of the IGBT varies depending on the output level of the inverter and the environmental condition of the inverter. A temperature difference between IGBTs can be detected.
If the IGBTs in the same group show abnormal signs in the same direction in increasing or decreasing the voltage drop, the S / N is improved because the temperature detecting diodes are connected in series and the series voltage is used. And the reliability of diagnosis is improved.
Further, since the temperature detecting diodes are connected in series and the voltages of the serially connected temperature detecting diodes are compared, the number of comparison circuits can be reduced, and a simple diagnostic circuit can be realized.
[0017]
Note that the IGBT 3 and the temperature detection diode 4 do not necessarily need to be formed on the same substrate, and the temperature detection diode 4 may be arranged near the IGBT 3 and built in the semiconductor module.
Further, the CPU 11 may be shared with a CPU (not shown) that performs the original control of the inverter, that is, controls the drive signal S1.
[0018]
Next, a second embodiment will be described. FIG. 2 shows the overall configuration of this embodiment.
In the present embodiment, the sum of the series output voltages of the two sets of the temperature detecting diodes 4 divided into two sets of the first embodiment is calculated by the difference circuit 6, and the abnormality is diagnosed from the difference voltage. , The sum of the series output voltages of the set of the temperature detection diodes 4 c and 4 d is input to the two comparison circuits 9 and 9 ′ of the over-temperature detection circuit 13. Voltage _{V ref1} to the comparator circuit 9 _'reference voltage circuit 14 is, the comparator circuit 9'_'reference voltage circuit 14' of the voltage _{V ref2} is connected to. When a series output voltage sum of a pair of temperature detecting diodes 4c and 4d lower than the respective reference voltages is input, a high temperature alarm signal S3 is sent from the comparison circuit 9 to the CPU 11, and a high temperature alarm signal is sent to the CPU 11 from the comparison circuit 9 '. S4 comes out.
Others are the same as the first embodiment.
[0019]
In order to protect one IGBT from an over-temperature rise, the reference voltage for issuing a high temperature alarm (limited to 50% inverter output) is V _ref1 , and the reference voltage for issuing a high temperature alarm (inverter stop) is V _{If ref2} is used, the reference voltage _{Vref1 '} and the reference voltage _Vref2' are calculated as follows.
Note that the forward current voltage drop of the temperature detecting diode 4 decreases as the temperature increases, so that V _ref1 > V _ref2 and V _{ref1 ′} > V _{ref2 ′} .

here,
V ^* : Voltage drop of the temperature detecting diode 4 with respect to the assumed maximum temperature during normal operation of the inverter
FIG. 3 shows an abnormality diagnosis logic executed by the CPU 11 in the present embodiment.
The CPU 11 performs abnormality diagnosis as described below based on the presence or absence of the signals of S2 from the comparison abnormality detection circuit 12 and the above-described S3 and S4.
First, in step 101, the S2 signal output when there is a difference _{exceeding the} threshold value _{Vref_diff} between the sum of the series output voltages of the two sets of temperature detecting diodes 4a, 4b and 4c, 4d in the comparison abnormality detecting circuit 12. It is determined whether or not there is a possibility of a comparison abnormality based on the presence or absence of the error. If there is no difference exceeding the threshold, the process proceeds to step 102, and if the difference exceeds the threshold, the process proceeds to step 104.
In step 102, it is confirmed whether or not the sum of the series output voltages of the temperature detecting diodes 4 c and 4 d falls below V _{ref1 ′} and the over-temperature detecting circuit 13 outputs the high temperature warning signal S 3. If the S3 signal has not been output, the routine proceeds to step 103. When the S3 signal is output, the process proceeds to step 107.
In step 103, all the IGBTs are determined to be normal, and a "normal" light indicating a normal state, for example, a green light is turned on.
[0021]
In step 104, it is checked whether the sum of the series output voltages of the temperature detecting diodes 4 c and 4 d is lower than V _{ref1 ′} and the over-temperature detecting circuit 13 outputs the high temperature alarm signal S 3. If the S3 signal has not been output, the process proceeds to step 105. When the S3 signal is output, the process proceeds to step 107.
In step 105, it is determined that any of the IGBTs has a fixed OFF fault, an output signal for limiting the inverter output to 50% is output, and the process proceeds to step 106.
In step 106, it is determined that the IGBT is not in an over-temperature state, and a "comparison abnormality alarm" lamp indicating a comparison abnormality state, for example, a yellow lamp is turned on.
[0022]
In step 107, it is checked whether the sum of the serial output voltages of the temperature detecting diodes 4c and 4d falls below _{Vref2 '} , and the over-temperature detecting circuit 13 outputs the high temperature alarm signal S4. If the S4 signal has not been output, the process proceeds to step 108. When the S4 signal is output, the process proceeds to step 110.
In step 108, it is determined that the IGBT is in the first-stage over-temperature abnormal state where the IGBT is in the over-temperature state but it is not necessary to stop the motor drive, and outputs an output signal for limiting the inverter output to 50%.
In step 109, one "high temperature alarm" light, for example, one red light, indicating the first stage state of the over-temperature abnormality is turned on.
[0023]
In step 110, the IGBT determines that the over-temperature state is the second-stage over-temperature state in which there is a possibility of equipment damage, and stops the inverter output.
In step 111, two "high temperature alarm" lights, for example, two red lights, indicating the second stage state of the over-temperature abnormality are turned on.
[0024]
In the present embodiment, the IGBT 3 corresponds to the semiconductor element of the present invention, the difference circuit 6 corresponds to the difference calculation means, and the comparison circuit 8 corresponds to the abnormality detection means.
[0025]
This embodiment is configured as described above, and as in the first embodiment, the temperature detecting diodes provided corresponding to the plurality of IGBTs connected in parallel are divided into two sets, and the temperature detecting diodes of each set are divided into two sets. The sum of the series output voltages of the diodes is compared, and when the difference between the series output voltage sums exceeds the threshold value _{Vref_diff} , it is determined to be abnormal. Therefore, the temperature of the IGBT _depends on the output level of the inverter and the environmental condition of the inverter. However, the temperature difference between the IGBTs can be detected even though the temperature changes.
If the IGBTs in the same set show abnormal signs in the same direction, the temperature detection diodes are connected in series and the series voltage is used, so that the S / N is improved and the reliability of diagnosis is improved. The performance is improved.
Further, since the temperature detecting diodes are connected in series and the voltages of the serially connected temperature detecting diodes are compared, the number of comparison circuits can be reduced, and a simple diagnostic circuit can be realized.
[0026]
In the present embodiment, the sum of the series output voltages of the at least one set of temperature detecting diodes connected in series is determined by the over-temperature detecting circuit. Even if the comparison abnormality detection circuit 12 cannot detect the abnormality, the overtemperature detection circuit 13 can detect the abnormality.
Since one over-temperature detecting circuit 13 is also provided for at least one set of temperature detecting diodes connected in series, one over-temperature detecting circuit is provided for one IGBT as in the related art. The number of circuits can be greatly reduced as compared with that of the prior art, and it can be realized by a simple diagnostic circuit.
[0027]
When one of a plurality of IGBTs connected in parallel in an IGBT of the same manufacturing lot fails and an overcurrent occurs, it is highly possible that the other IGBTs also have the same failure at the same time. In the example, the over-temperature detection circuit 13 has a simplified configuration in which only one of the series output voltage sums of the series-connected temperature detection diodes that are compared in the comparison abnormal circuit is determined.
In that case, the reference voltages V _{ref1 ′} and V _{ref2 ′} of the over-temperature detection circuit 13 may be simplified as in the following equation instead of the equations (2) and (3).
V _{ref1 ′} = V _ref1 × n (2 ′)
V _{ref2 ′} = V _ref2 × n (3 ′)
[0028]
In the above-described embodiments of the present invention, an IGBT has been described as an example of a semiconductor element. However, the semiconductor element is not limited to an IGBT, and may be, for example, a transistor, an SCR, or a diode. Furthermore, the semiconductor substrate incorporating one semiconductor element (IGBT) has been described as an example, but the present invention can also be applied to a semiconductor substrate incorporating two or more semiconductor elements.
[0029]
[Brief description of the drawings]
FIG. 1 is a diagram showing a configuration of an abnormality diagnosis circuit according to a first embodiment of the present invention.
FIG. 2 is a diagram showing a configuration of a second embodiment.
FIG. 3 is a diagram illustrating an abnormality diagnosis logic according to a second embodiment.
[Explanation of symbols]
1 semiconductor module 2, 2a-2d semiconductor substrate 3, 3a-3d IGBT
4, 4a-4d Temperature detecting diode 5 Constant current circuit 6 Difference circuit 7, 7 'Reference voltage circuit 8, 8' Comparison circuit 9, 9 'Comparison circuit 11 CPU
12 comparison abnormality detection circuit 13 over-temperature detection circuit 14, 14 'reference voltage circuit S1 IGBT drive signal S2 comparison abnormality signal S3 high temperature alarm signal S4 high temperature alarm signal

Claims (3)

In a semiconductor abnormality diagnosis circuit for detecting abnormality of a semiconductor module including a plurality of semiconductor elements and a temperature detection diode for detecting the temperature thereof,
Dividing the temperature detecting diode into at least two sets,
The temperature detection diodes included in each set are connected in series, and a constant current is supplied from a constant current circuit to the temperature detection diodes connected in series,
Difference calculating means for calculating the difference between the series output voltage sums of the temperature detecting diodes of each set,
An abnormality diagnosis circuit for a semiconductor element, comprising: abnormality detection means for detecting a case where the difference output by the difference calculation means is equal to or more than a predetermined value and issuing a signal. 2. The abnormality diagnosis circuit according to claim 1, wherein the plurality of semiconductor elements are connected in parallel. Among the series output voltage sums of the temperature detection diodes, the series output voltage sums of at least one set of temperature detection diodes are connected to an over-temperature detection circuit including a comparison circuit for comparing with a reference voltage of a predetermined value, and 3. The abnormality diagnosis circuit for a semiconductor device according to claim 1, wherein the temperature detection circuit issues a signal when the temperature falls below the reference voltage.

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