DE102020006870A1 - Monitoring device for a semiconductor electric power device - Google Patents

Abstract

The invention relates to a monitoring device (100) for an electrical semiconductor power device (50) of an electrically operable vehicle, the semiconductor power device (50) comprising at least one power semiconductor element (10) and an electrical protection path (12) for protecting the power semiconductor element (10) from overvoltage effects , wherein the protective path (12) has a diode (14) connected in series with an electrical resistor (16). A monitoring unit (20) is provided for monitoring a voltage curve over time at the resistor (16), the monitoring unit (20) being designed to set a safe state (S2 ) of the semiconductor power device (50). The invention further relates to a method for operating such a monitoring device (100).

Description

The invention relates to a monitoring device for an electrical semiconductor power device of an electrically operable vehicle and a method for operating a monitoring device for an electrical semiconductor power device of an electrically operable vehicle.

Very high electrical power is converted in a motor inverter of an electrically operated vehicle. the direct current (DC) power is converted into alternating current (AC) power in the inverter.

Inverters often use insulated gate bipolar transistors (IGBTs) as power semiconductor elements. IGBTs are used to control high power electric currents. Typical applications for IGBTs can be induction heating, motor drives and electric vehicles. An IGBT is sensitive to overvoltage conditions. Therefore, a driver for IGBTs should ensure robustness of the resulting system with regard to overvoltage.

the DE 102017002573 A1 discloses a drive device for driving a semiconductor power device, for example an IGBT, comprising a first terminal designed for connection to a first terminal of the power device, a gate terminal designed for providing a drive signal for a gate terminal of the power device, and a sensor for detecting overvoltage conditions at the first terminal of the power device, wherein the drive circuitry is configured to modify the drive signal when the sensor detects an indication of an overvoltage condition, and wherein the drive circuitry including the sensor is integrated on a single substrate.

An object of the invention is to provide a monitoring device for a semiconductor electric power device in order to prevent possible damage to power semiconductor elements.

A further object is to specify a method for operating such a monitoring device for a semiconductor electric power device.

The aforementioned objects are solved with the features of the independent claims.

Favorable configurations and advantages of the invention result from the further claims, the description and the drawing.

According to one aspect of the invention, a monitoring device for an electrical semiconductor power device of an electrically operable vehicle is proposed, the semiconductor power device comprising at least one power semiconductor element and an electrical protection path for protecting the power semiconductor element from overvoltage effects, the protection path having a diode connected in series with an electrical resistance . A monitoring unit is provided for monitoring a voltage profile over time at the resistor, the monitoring unit being designed to bring about a safe state of the semiconductor power device if the voltage profile at the resistor deviates from a characteristic voltage profile.

During switch-off processes in an IGBT of the inverter of an electrically operable vehicle, voltage peaks can occur due to the dissolution of the inductive commutation circuit. As soon as these voltage peaks exceed a critical voltage, e.g. at an IGBT, a so-called protection path is usually activated. This protection path causes the gate voltage on the IGBT to be activated briefly as soon as the collector-emitter voltage reaches a certain voltage value. The very short pulse, around 50 - 70 nanoseconds, causes the collector-emitter voltage on the IGBT to be dampened. The IGBT, which is irreversibly damaged if the maximum collector-emitter voltage is exceeded, can thus be protected via the protection path. The essential part of the protection path often consists of a very fast diode that is operated in the blocking range, a so-called suppressor diode. If the characteristic of the diode changes, then in the worst case a bridge short circuit can occur between the so-called high-side IGBTs and the low-side IGBTs of the semiconductor power device. This can irreparably damage the semiconductor power device.

With the monitoring device according to the invention, a change in the characteristic of the diode can be detected at an early stage and the semiconductor power device can be put into a safe state. In this way, damage to the power semiconductor element and consequential damage to the semiconductor power device can advantageously be avoided.

In order to avoid damaging the motor inverter or a semiconductor power device of the motor inverter, the protection path is monitored by determining the voltage drop across an electrical resistor. If the diode is OK, the voltage is always the same walk over the resistance. An evaluation logic in the monitoring unit can thus adjust the characteristic voltage curve for each switching operation in which the diode opens. If the characteristic of the diode changes, the characteristic voltage curve across the resistor also changes. The evaluation logic notices the change and immediately initiates the safe state of the semiconductor power device. Further damage to the power semiconductor element or the semiconductor power device can be avoided as a result.

According to an advantageous embodiment of the monitoring device, the power semiconductor element can be a bipolar transistor with an insulated gate, it being possible for the protective path to be formed between a collector and a gate of the bipolar transistor. The protection path causes the gate voltage on the IGBT to be activated briefly as soon as the collector-emitter voltage reaches a certain voltage value. The very short pulse, around 50 - 70 nanoseconds, causes the collector-emitter voltage on the IGBT to be dampened. The IGBT, which is irreversibly damaged if the maximum collector-emitter voltage is exceeded, can thus be protected via the protection path.

According to an advantageous embodiment of the monitoring device, the voltage curve across the resistor can be determined by the monitoring unit each time the diode opens. As a result, a change in the characteristic of the diode can be recognized as promptly as possible with a high degree of certainty, so that possible damage to the power semiconductor element can be avoided by putting the semiconductor power device in a safe state.

According to a further aspect of the invention, a method for operating a monitoring device for an electrical semiconductor power device of an electrically operable vehicle is proposed, the semiconductor power device comprising at least one power semiconductor element and an electrical protection path for protecting the power semiconductor element from overvoltage effects, the protection path being in series with a has electrical resistance connected diode. A monitoring unit is provided for monitoring a voltage profile over time at the resistor.

The method comprises at least the steps of determining a voltage profile across the resistor by the monitoring unit; Comparing the voltage curve with a characteristic voltage curve; If the voltage waveform does not deviate from the characteristic voltage waveform, continuing normal operation of the semiconductor power device; otherwise putting the semiconductor power device in a safe state.

According to an advantageous embodiment of the method, the monitoring unit can determine a voltage profile at the resistor each time the diode opens. As a result, a change in the characteristic of the diode can be recognized as promptly as possible with a high degree of certainty, so that possible damage to the power semiconductor element can be avoided by putting the semiconductor power device in a safe state.

According to an advantageous embodiment of the method, a characteristic curve and/or a family of characteristic curves of the characteristic voltage curve can be stored in the monitoring unit. As a result, the correct characteristic curve or the correct family of characteristics is available to an evaluation logic in the monitoring unit for a comparison of the measured voltage curve at the resistor with a setpoint voltage curve. As a result, changes in the characteristic of the diode can be detected early, so that possible damage to the power semiconductor element can be avoided by putting the semiconductor power device in a safe state

Further advantages result from the following description of the drawings. In the drawings an embodiment of the invention is shown. The drawings, the description and the claims contain numerous features in combination. The person skilled in the art will expediently also consider the features individually and combine them into further meaningful combinations.

• 1 eine Systemübersicht einer Überwachungsvorrichtung für eine elektrische Halbleiterleistungsvorrichtung eines elektrisch betreibbaren Fahrzeugs nach einem Ausführungsbeispiel der Erfindung; und
• 2 ein Ablaufdiagramm des Verfahrens nach einem Ausführungsbeispiel der Erfindung zum Betreiben einer Überwachungsvorrichtung nach 1.

show:

• 1 a system overview of a monitoring device for a semiconductor electric power device of an electrified vehicle according to an embodiment of the invention; and
• 2 a flowchart of the method according to an embodiment of the invention for operating a monitoring device 1 .

In the figures, the same or similar components are denoted by the same reference symbols. The figures only show examples and are not to be understood as limiting.

1 shows a system overview of a monitoring device 100 for an electrical semi conductor power device 50 of an electrified vehicle according to an embodiment of the invention. The system overview shows a purely schematic representation of the monitoring device using the example of a semiconductor power device 50 with a power semiconductor element 10 which has a collector 10, a gate G and an emitter E.

The semiconductor power device 50, for example for a motor inverter of an electrically operable vehicle, comprises the power semiconductor element 10 and an electrical protection path 12 for protecting the power semiconductor element 10 from overvoltage effects. The protective path 12 has a diode 14 connected in series with an electrical resistor 16 .

The power semiconductor element 10 is an insulated gate bipolar transistor (IGBT). The protection path 12 is formed between the collector C and the gate G of the bipolar transistor.

A monitoring unit 20 is provided for monitoring a voltage curve over time at the resistor 16 . For this purpose, the monitoring unit 20 can have evaluation logic with a microcontroller in order to measure and evaluate the voltage drop across the resistor 16 . The voltage drop across the resistor 16 is measured via two signal lines 22, 24.

The monitoring unit 20 is designed to put the semiconductor power device 50 into a safe state S2 if the voltage profile at the resistor 16 deviates from a characteristic voltage profile. For this purpose, the voltage curve across the resistor 16 can advantageously be determined by the monitoring unit 20 during each opening process of the diode 14 .

If the voltage curve across the resistor measured by monitoring unit 20 does not deviate from the characteristic voltage curves stored in monitoring unit 20, then monitoring unit 20 uses a first signal 30 for a correct voltage curve to signal that semiconductor power device 50 can continue to be operated in normal operation S1.

If, on the other hand, the measured voltage curve deviates from the stored characteristic voltage curves, the monitoring unit 20 uses a second signal 32 for an improper voltage curve to signal that the semiconductor power device 50 is switched to a safe state. Further notifications can be output, for example, to a central control device in the vehicle and/or to the driver of the vehicle.

2 FIG. 1 shows a flowchart of the method according to an embodiment of the invention for operating a monitoring device 100. FIG 1 .

The method for operating the monitoring device 100 provides the following steps.

In a first step S100, the monitoring unit 20 continuously determines a voltage profile at the electrical resistor 16, which is connected in series to a diode 14 in the protection path 12 of the semiconductor power device 50.

After each measurement of the voltage profile, the voltage profile is compared with a characteristic voltage profile stored in the monitoring unit 20 in the following step S102. For this purpose, for example, a characteristic curve and/or a family of characteristic curves of the characteristic voltage curve can be stored in the monitoring unit 20 .

If the voltage curve does not deviate from the characteristic voltage curve, the normal operation S1 of the semiconductor power device 50 is continued in step S104 and the continuous monitoring of the voltage curve across the resistor 16 is resumed in step S100.

If the voltage profile deviates from the characteristic voltage profile, in step S106, the semiconductor power device 50 is placed in a safe state S2.

Advantageously, the voltage curve at the resistor can be carried out by the monitoring unit 20 each time the diode 14 opens.

Reference List

10

power semiconductor element

12

protection path

14

diode

16

Resistance

20

monitoring unit

22

tap

24

tap

30

first signal for proper voltage progression

32

second signal for incorrect voltage curve

50

semiconductor power device

100

monitoring device

C

collector

E

emitter

G

Gate

S1

normal operation

S2

Safe condition

QUOTES INCLUDED IN DESCRIPTION

This list of documents cited by the applicant was generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Patent Literature Cited

• DE 102017002573 A1 [0004]

Claims (6)

Monitoring apparatus (100) for an electric semiconductor power device (50) of an electrified vehicle, the semiconductor power device (50) comprising at least one - a power semiconductor element (10), and - an electrical protection path (12) for protecting the power semiconductor element (10) from overvoltage effects, the protection path (12) having a diode (14) connected in series with an electrical resistor (16), a monitoring unit (20) for monitoring a time voltage curve is provided at the resistor (16), the monitoring unit (20) being designed to bring about a safe state (S2) of the semiconductor power device (50) if the voltage curve at the resistor (16) deviates from a characteristic voltage curve. voltage limiting device claim 1 wherein the power semiconductor element (10) is an insulated gate bipolar transistor, and wherein the protection path (12) is formed between a collector (C) and a gate (G) of the bipolar transistor. Voltage-limiting device according to one of the preceding claims, in which the voltage curve across the resistor (16) can be determined by the monitoring unit (20) during each opening process of the diode (14). Method of operating a monitoring device (100) for an electric semiconductor power device (50) of an electrified vehicle according to any one of the preceding claims, wherein the semiconductor power device (50) comprises at least - a power semiconductor element (10), and - an electrical protection path (12) for protecting the power semiconductor element (10) from overvoltage effects, the protection path (12) having a diode (14) connected in series with an electrical resistor (16), a monitoring unit (20) for monitoring a time Voltage curve is provided at the resistor (16), the method comprising at least the steps - Determining a voltage profile across the resistor (16) by the monitoring unit (20); - Comparing the voltage curve with a characteristic voltage curve; - If the voltage curve does not deviate from the characteristic voltage curve, continuation of normal operation (S1) of the semiconductor power device (50); otherwise - placing the semiconductor power device (50) in a safe state (S2). procedure after claim 4 , wherein the determination of a voltage profile across the resistor by the monitoring unit (20) takes place each time the diode (14) opens. procedure after claim 4 or 5 , A characteristic curve and/or a family of characteristic curves of the characteristic voltage profile being stored in the monitoring unit (20).

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