DE102023201657A1 - Device and method for monitoring semiconductor switching elements, power modules and electrical power converters - Google Patents

Abstract

The invention relates to the monitoring of semiconductor switching elements in a half-bridge with several semiconductor switching elements arranged in parallel. In this case, the electrical voltages at the source terminals, in particular at the Kelvin source terminals of the semiconductor switching elements, are monitored and a malfunction, in particular a short circuit of the semiconductor switching element, is detected when a threshold value is exceeded.

Description

Technical area

The present invention relates to a device and method for monitoring semiconductor switching elements. The present invention further relates to a power module with such a device and to an electrical power converter.

State of the art

Electrical power converters generally use several half-bridges with semiconductor switching elements, each of which is opened and closed in a specific manner. This means that, for example, a direct current provided at an input connection of a power converter can be converted into a single-phase or multi-phase alternating current. For high electrical outputs, several semiconductor switching elements can be connected in parallel in the half-bridges.

During operation of such a power converter, it is desirable to reliably detect possible faults in semiconductor switching elements, such as a short circuit or a breakdown of a semiconductor switching element.

The publication EN 10 2017 106 181 A1 describes, for example, a driver circuit for transistor bridges with a short-circuit and/or open circuit detection

Disclosure of the invention

The present invention provides a device and method for monitoring semiconductor switching elements, a power module and an electrical power converter with the features of the independent patent claims. Further advantageous embodiments are the subject of the dependent patent claims.

• Eine Vorrichtung zur Überwachung von Halbleiterschaltelementen in einer Halbbrücke. Die Halbbrücke umfasst hierbei mehrere obere Halbleiterschaltelemente und mehrere untere Halbleiterschaltelemente. Die mehreren oberen Halbleiterschaltelemente sind jeweils zwischen einem positiven Anschlusspunkt und einem Knotenpunkt angeordnet. Die mehreren unteren Halbleiterschaltelemente sind jeweils zwischen dem Knotenpunkt und einem negativen Anschlusspunkt angeordnet. Die Gateanschlüsse der oberen Halbleiterschaltelemente sind mit einer ersten Treiberschaltung elektrisch gekoppelt. Analog sind die Gateanschlüsse der unteren Halbleiterschaltelemente mit einer zweiten Treiberschaltung elektrisch gekoppelt. Die erste Treiberschaltung ist dazu ausgelegt, Ansteuersignale für die oberen Halbleiterschaltelemente bereitzustellen. Entsprechend ist die zweite Treiberschaltung dazu ausgelegt, Ansteuersignale für die unteren Halbleiterschaltelemente bereitzustellen. Ferner ist zwischen einem Bezugspotential der ersten Treiberschaltung und Sourceanschlüssen der oberen Halbleiterschaltelemente jeweils ein erster elektrischer Widerstand angeordnet ist. Ebenso ist zwischen einem weiteren Bezugspotential der zweiten Treiberschaltung und Sourceanschlüssen der unteren Halbleiterschaltelemente jeweils ein zweiter elektrischer Widerstand angeordnet. Die Vorrichtung zur Überwachung der Halbleiterschaltelemente umfasst eine erste Überwachungseinrichtung und eine zweite Überwachungseinrichtung. Die erste Überwachungseinrichtung ist dazu ausgelegt, eine Fehlfunktion in einem der oberen Halbleiterschaltelemente zu detektieren, falls ein Spannungsabfall über einen der ersten elektrischen Widerstände einem ersten vorbestimmten Wert überschreitet. Die zweite Überwachungseinrichtung ist dazu ausgelegt, eine Fehlfunktion in einem der unteren Halbleiterschaltelemente zu detektieren, falls ein Spannungsabfall über einem der zweiten elektrischen Widerstände einen zweiten vorbestimmten Wert überschreitet.

Accordingly, it is envisaged:

• A device for monitoring semiconductor switching elements in a half-bridge. The half-bridge comprises a plurality of upper semiconductor switching elements and a plurality of lower semiconductor switching elements. The plurality of upper semiconductor switching elements are each arranged between a positive connection point and a node point. The plurality of lower semiconductor switching elements are each arranged between the node point and a negative connection point. The gate connections of the upper semiconductor switching elements are electrically coupled to a first driver circuit. Similarly, the gate connections of the lower semiconductor switching elements are electrically coupled to a second driver circuit. The first driver circuit is designed to provide control signals for the upper semiconductor switching elements. Accordingly, the second driver circuit is designed to provide control signals for the lower semiconductor switching elements. Furthermore, a first electrical resistor is arranged between a reference potential of the first driver circuit and source connections of the upper semiconductor switching elements. Likewise, a second electrical resistor is arranged between a further reference potential of the second driver circuit and source connections of the lower semiconductor switching elements. The device for monitoring the semiconductor switching elements comprises a first monitoring device and a second monitoring device. The first monitoring device is designed to detect a malfunction in one of the upper semiconductor switching elements if a voltage drop across one of the first electrical resistors exceeds a first predetermined value. The second monitoring device is designed to detect a malfunction in one of the lower semiconductor switching elements if a voltage drop across one of the second electrical resistors exceeds a second predetermined value.

Furthermore, it is planned:

A power module with a half-bridge, wherein the half-bridge comprises a plurality of upper semiconductor switching elements and a plurality of lower semiconductor switching elements. The plurality of upper semiconductor switching elements are each arranged between a positive connection point and a node point. Furthermore, the plurality of lower semiconductor switching elements are each arranged between the node point and a negative connection point. The gate connections of the upper semiconductor switching elements are electrically coupled to a first driver circuit. The gate connections of the lower semiconductor switching elements are electrically coupled to a second driver circuit. The first driver circuit is designed to provide control signals for the upper semiconductor switching elements. The second driver circuit is designed to provide control signals for the lower semiconductor switching elements. A first electrical resistor is arranged between a reference potential of the first driver circuit and source connections of the upper semiconductor switching elements. Similarly, a further reference potential of the second driver circuit and source connections of the lower semiconductor A second electrical resistor is arranged in each case for each switching element. The power module further comprises a device according to the invention for monitoring the semiconductor switching elements.

It is also planned:

An electrical power converter with several power modules according to the invention.

Finally, it is planned:

A method for monitoring semiconductor switching elements in a half-bridge, wherein the half-bridge comprises a plurality of upper and lower semiconductor switching elements. The plurality of upper semiconductor switching elements are each arranged between a positive connection point and a node point. The plurality of lower semiconductor switching elements are each arranged between the node point and a negative connection point. The gate connections of the upper semiconductor switching elements are electrically coupled to a first driver circuit. Analogously, the gate connections of the lower semiconductor switching elements are electrically coupled to a second driver circuit. The first driver circuit is designed to provide control signals for the upper semiconductor switching elements. Accordingly, the second driver circuit is designed to provide control signals for the lower semiconductor switching elements. Furthermore, a first electrical resistor is arranged between a reference potential of the first driver circuit and source connections of the upper semiconductor switching elements. Likewise, a second electrical resistor is arranged between a further reference potential of the second driver circuit and source connections of the lower semiconductor switching elements. The method is capable of detecting a malfunction in one of the semiconductor switching elements if a voltage drop across one of the electrical resistances between the source terminals and the reference potential of the first driver stage or the second driver stage exceeds a predetermined value.

Advantages of the invention

The present invention is based on the finding that the monitoring and fault detection of semiconductor switching elements in half bridges of power modules, such as those used in electrical power converters, is of great importance. In particular, a simple, fast and reliable detection of short circuits, such as those that can occur when semiconductor switching elements fail, is desirable.

The present invention makes use of existing circuit structures of half-bridges with several semiconductor switching elements arranged in parallel. According to the invention, a quick, reliable detection of short circuits in semiconductor switching elements in half-bridges with several semiconductor switching elements arranged in parallel can be realized by a simple evaluation circuit which analyzes the potential of the existing circuit structure. This enables a cost-effective, quick and reliable detection of short circuits in semiconductor switching elements in half-bridges with several semiconductor switching elements arranged in parallel.

Due to the parasitic properties in the line sections that are connected to the source terminals of the semiconductor switching element, such as parasitic inductances, voltage drops occur across this line section. In particular, the voltage drop across such a line section increases significantly in the event of a short circuit due to a faulty semiconductor switching element. Such an increased voltage drop can be detected by the monitoring according to the invention and thus a fault in the semiconductor switching element can be identified.

According to one embodiment, the first monitoring device and the second monitoring device each comprise a monitoring resistor and a plurality of capacitors. The monitoring resistor of such a monitoring device is arranged between a first test point and a second test point. Furthermore, the plurality of capacitors are each arranged between one of the source terminals of a semiconductor switching element and the first test point or the second test point. At least one capacitor is connected to each of the two test points. If there is an even number of semiconductor switching elements to be monitored, for example, half of the source terminals of the semiconductor switching elements to be monitored can be coupled to the first test point via capacitors, and the other half of the source terminals can be coupled to the second test point via capacitors. If there is an odd number of semiconductor switching elements to be monitored, for example, one more capacitor can be connected to one of the two test points than to the other test point.

According to one embodiment, the first monitoring device and the second monitoring device are each designed to detect a malfunction in a semiconductor switching element using a level of the electrical voltage between the first test point and the second test point. In particular, a malfunction in one of the semiconductor switching elements can be detected if the amount of the electrical voltage exceeds a predetermined threshold value. Furthermore, using the sign of the electrical voltage, it can be determined whether the faulty switching element is a switching element which is connected to the first test point or the second test point via a capacitor.

The above embodiments and developments can be combined with one another as desired, provided this makes sense. Further embodiments, developments and implementations of the invention also include combinations of features of the invention described above or below with regard to the exemplary embodiments that are not explicitly mentioned. In particular, the person skilled in the art will also add individual aspects as improvements or additions to the respective basic forms of the invention.

Short description of the drawings

• 1: ein Prinzipschaltbild eines Leistungsmoduls mit einer Überwachungseinrichtung gemäß einer Ausführungsform; und
• 2: ein Prinzipschaltbild einer Überwachungseinrichtung gemäß einer Ausführungsform.

Further features and advantages of the invention are explained below with reference to the figures.

• 1 : a schematic diagram of a power module with a monitoring device according to an embodiment; and
• 2 : a schematic diagram of a monitoring device according to an embodiment.

Description of embodiments

1 shows a basic circuit diagram of a power module with a device for monitoring semiconductor switching elements according to an embodiment. The power module comprises a half-bridge with a first group of upper semiconductor switching elements M11, M12 and a second group of lower semiconductor switching elements M21, M22. The upper semiconductor switching elements M11, M12 are arranged parallel to one another between a positive connection point A1 and a node K. The lower semiconductor switching elements M21, M22 are arranged parallel to one another between the node and a negative connection point A2. Although in 1 only two upper semiconductor switching elements M11 and M12 and two lower semiconductor switching elements M21 and M22 are shown, the present invention is not limited to this. Rather, in principle any number of semiconductor switching elements can be provided in parallel to one another. The semiconductor switching elements can be MOSFETs, for example. In principle, however, other suitable semiconductor switching elements are also possible.

The control terminals of the upper semiconductor switching elements M11, M12 are controlled by a first driver circuit TS1. The control terminals of the lower semiconductor switching elements M21, M22 are controlled by a second driver circuit TS2. The first driver circuit is connected to a first reference potential GND1. The second driver circuit is connected to a second reference potential GND2.

The 1 The inductances L11, L12, L21, L22 shown represent the parasitic inductances in the respective line sections.

The source terminals of the first semiconductor switching elements M11, M12 are coupled to the first reference potential GND1 via discrete resistors R11, R12. The source terminals of the second semiconductor switching elements M21, M22 are also coupled to the second reference potential GND2 via discrete resistors R212, R22. In particular, these resistors R11, R12, R21, R22 can be connected to so-called Kelvin source terminals of the respective semiconductor switching elements M11, M12, M21, M22.

Furthermore, a first monitoring device 10 for monitoring the upper semiconductor switching elements M11, M12 and a second monitoring device 20 for monitoring the lower semiconductor switching elements M21, M22 are provided in the power module. These monitoring devices 10 and 20 can detect a malfunction, in particular a short circuit or a breakdown of one of the semiconductor switching elements M11, M12, M21, M22. To this end, the monitoring devices 10 and 20 monitor the potential at the source or Kelvin source connections of the semiconductor switching elements M11, M12, M21, M22 or a voltage drop across the resistors R11, R12, R21, R22 between the source connections of the semiconductor switching elements M11, M12, M21, M22 and the respective driver stages TS1, TS2.

Since in the event of a short circuit at one of the semiconductor switching elements M11, M12, M21, M22 the electrical current will increase sharply, the voltage drop across the respective parasitic inductances L11, L12, L21, L22 in the corresponding line section increases, which also leads to an increased voltage drop across the corresponding resistor R11, R12, R21, R22. Thus, the monitoring devices 10, 20 can detect a fault in one of the semiconductor switching elements M11, M12, M21, M22 if the electrical voltage across one of the resistors R11, R12, R21, R22 increases.

In the event of such a detection, a corresponding signal can be issued. In particular, suitable measures such as an emergency shutdown or a change to a safe state can be initiated.

2 shows a basic circuit diagram of a monitoring device 10 or 20 for monitoring the semiconductor switching elements in a half-bridge according to an embodiment. The structure of the half-bridge with the semiconductor switching element largely corresponds to that previously described in connection with 1 described structure. For a better understanding, 2 However, a power module with a half-bridge is used, which comprises four upper semiconductor switching elements M11 to M14 and four lower semiconductor switching elements M21 to M24.

The following describes the structure of a monitoring device 10 for monitoring the upper semiconductor switching elements M11 to M14 as it is also described in 2 is shown in detail. The structure and function of the monitoring device 20 for monitoring the lower semiconductor switching elements M21 to M24 is identical.

As in 2 is to be recognized, the monitoring device 10 comprises a plurality of capacitors C11 to C14. In particular, a capacitor C11 to C14 is provided for each semiconductor switching element M11 to M14 to be monitored. In each case, one connection of a capacitor is connected to a source connection of a semiconductor switching element M11 to M14. The other connections of the capacitors C11 to C14 are connected either to a first connection point T1 or to a second connection point T2. Preferably, at least approximately the same number of capacitors are connected to the first connection point T1 and the second connection point T2. With an odd number of semiconductor switching elements M11 to M14 to be monitored and accordingly an odd number of capacitors C11 to C14, for example, one more capacitor can be connected to one of the two connection points T1 or T2 than to the other connection point T1 or T2. In principle, however, concepts deviating from this would also be possible.

A monitoring resistor R is arranged between the first connection point T1 and the second connection point T2. Furthermore, a capacitor C can be provided between the first connection point T1 and the second connection point T2.

The electrical voltage across the monitoring resistor R can be monitored and evaluated by means of a monitoring circuit 11. In particular, this monitoring circuit 11 can detect a malfunction in one of the semiconductor switches M11 to M14 to be monitored if the amount of an electrical voltage across the monitoring resistor R exceeds a predetermined threshold value. In this case, based on the sign of the electrical voltage across the monitoring resistor R, it can be concluded whether the malfunction occurs at a semiconductor switching element M11, M12, which is connected to the first connection point T1 via the corresponding capacitor C11, C12, or whether the malfunction occurs at a semiconductor switching element M13, M14, which is connected to the second connection point T2 via the corresponding capacitor C13, C14.

In principle, any approach and circuit concept is possible for evaluating the electrical voltage across the monitoring resistor R. For example, a window comparator can be provided for this purpose, which outputs a detection signal both when the electrical voltage across the monitoring resistor R exceeds and falls below a predetermined threshold. For example, the detection of a malfunction in one of the semiconductor switching elements M11 to M14 can be implemented using discrete components such as diodes, resistors, etc. Alternatively, digital evaluation is also possible, in which the electrical voltage across the monitoring resistor R is converted into a digital value using an A/D converter and this digital value is then further processed.

In summary, the present invention relates to the monitoring of semiconductor switching elements in a half-bridge with several semiconductor switching elements arranged in parallel. In this case, it is provided to monitor the electrical voltages at the source terminals, in particular at the Kelvin source terminals of the semiconductor switching elements, and to detect a malfunction, in particular a short circuit of the semiconductor switching element, when a threshold value is exceeded.

QUOTES INCLUDED IN THE DESCRIPTION

This list of documents listed 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 accepts no liability for any errors or omissions.

Cited patent literature

• DE 102017106181 A1 [0004]

Claims (7)

Device for monitoring semiconductor switching elements (M11, M12, M21, M22) in a half-bridge, wherein the half-bridge comprises a plurality of upper semiconductor switching elements (M11, M12) and a plurality of lower semiconductor switching elements (M21, M22), the plurality of upper semiconductor switching elements (M11, M12) are each arranged between a positive connection point (A1) and a node point (K) and the plurality of lower semiconductor switching elements (M21, M22) are each arranged between the node point (K) and a negative connection point (A2), wherein gate connections of the upper semiconductor switching elements (M11, M12) are electrically coupled to a first driver circuit (TS1) and the first driver circuit (TS1) is designed to provide control signals for the upper semiconductor switching elements (M11, M12), and where gate connections of the lower semiconductor switching elements (M21, M22) are electrically coupled to a second driver circuit (TS2) and the second driver circuit (TS2) is designed to provide control signals for the lower semiconductor switching elements (M21, M22), wherein a first electrical resistor (R11, R12) is arranged between a first reference potential (GND1) of the first driver circuit (TS1) and source terminals of the upper semiconductor switching elements (M11, M12), and a second electrical resistor (R21, R22) is arranged between a second reference potential (GND2) of the second driver circuit (TS2) and source terminals of the lower semiconductor switching elements (M21, M22), and wherein the device for monitoring the semiconductor switching elements (M11, M12, M21, M22) comprises a first monitoring device (10) and a second monitoring device (20), wherein the first monitoring device (10) is designed to detect a malfunction in one of the upper semiconductor switching elements (M11, M12) if a voltage drop across one of the first electrical resistors (R11, R12) exceeds a first predetermined value, and wherein the second monitoring device (20) is designed to detect a malfunction in one of the lower semiconductor switching elements (M21, M22) if a voltage drop across one of the second electrical resistors (R21, R22) exceeds a second predetermined value. Device according to Claim 1 , wherein the first monitoring device (10) and the second monitoring device (20) each comprise a monitoring resistor (R) and a plurality of capacitors (C11, C12, C13, C14), wherein the monitoring resistor (R) is arranged between a first connection point (T1) and a second connection point (T2) of the respective monitoring device (10, 20), and wherein the plurality of capacitors (C11, C12, C13, C14) are each arranged between one of the source terminals of a semiconductor switching element (M11, M12, M13, M14) and the first connection point (T1) or the second connection point (T2). Device according to Claim 2 , wherein the first monitoring device (10) and the second monitoring device (20) are each designed to detect a malfunction in a semiconductor switching element (M11, M12, M13, M14) using a level of the electrical voltage between the first connection point (T1) and the second connection point (T2). Power module with a half-bridge, wherein the half-bridge comprises a plurality of upper semiconductor switching elements (M11, M12) and a plurality of lower semiconductor switching elements (M21, M22), wherein the plurality of upper semiconductor switching elements (M11, M12) are each arranged between a positive connection point (A1) and a node point (K) and the plurality of lower semiconductor switching elements (M21, M22) are each arranged between the node point (K) and a negative connection point (A2), wherein gate connections of the upper semiconductor switching elements (M11, M12) are electrically coupled to a first driver circuit (TS1) and the first driver circuit (TS1) is designed to provide control signals for the upper semiconductor switching elements (M11, M12), and wherein gate connections of the lower semiconductor switching elements (M21, M22) are electrically coupled to a second driver circuit (TS2) and the second driver circuit (TS2) is designed to provide control signals for the lower semiconductor switching elements (M21, M22), wherein a first electrical resistor (R11, R12) is arranged between a first reference potential (GND1) of the first driver circuit (TS1) and source terminals of the upper semiconductor switching elements (M11, M12), and a second electrical resistor (R21, R22) is arranged between a second reference potential (GND2) of the second driver circuit (TS2) and source terminals of the lower semiconductor switching elements (M21, M22), and wherein the power module further comprises a device for monitoring the semiconductor switching elements (M11, M12, M21, M22) according to one of the Claims 1 until 3 includes. Power modules according to Claim 4 , wherein the upper semiconductor switching elements (M11, M12) and the lower semiconductor switching elements (M21, M22) each comprise a Kelvin source terminal and the first resistors (R11, R12) and the second resistors (R21, R22) are arranged between the Kelvin source terminals and the reference potential (GND1) of the first driver stage (TS1) or the second driver stage (TS2). Electrical power converter with multiple power modules according to Claim 5 . Method for monitoring semiconductor switching elements (M11, M12, M21, M22) in a half-bridge, wherein the half-bridge comprises a plurality of upper semiconductor switching elements (M11, M12) and a plurality of lower semiconductor switching elements (M21, M22), the plurality of upper semiconductor switching elements (M11, M12) are each arranged between a positive connection point (A1) and a node point (K) and the plurality of lower semiconductor switching elements (M21, M22) are each arranged between the node point (K) and a negative connection point (A2), wherein gate connections of the upper semiconductor switching elements (M11, M12) are electrically coupled to a first driver circuit (TS1) and the first driver circuit (TS1) is designed to provide control signals for the upper semiconductor switching elements (M11, M12), and where gate connections of the lower semiconductor switching elements (M21, M22) are electrically coupled to a second driver circuit (TS2) and the second driver circuit (TS2) is designed to provide control signals for the lower semiconductor switching elements (M21, M22), wherein a first electrical resistor (R11, R12) is arranged between a first reference potential (GND1) of the first driver circuit (TS1) and source terminals of the upper semiconductor switching elements (M11, M12), and a second electrical resistor (R21, R22) is arranged between a second reference potential (GND2) of the second driver circuit (TS2) and source terminals of the lower semiconductor switching elements (M21, M22), and wherein the method detects a malfunction in one of the semiconductor switching elements (M11, M12, M21, M22) if a voltage drop across one of the electrical resistors (R11, R12, R21, R22) between the source terminals and the reference potential (GND1) of the first driver stage (TS1) or the reference potential (GND2) of the second driver stage (TS2) exceeds a predetermined value.

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