ELECTRICAL POWER CONVERSION DEVICE

Abstract

Electrical power conversion device (10a; 10b; 10c; 10d; 10e; 10f) with an inverter arm (10) in which an upper arm switching element (30) and a lower arm switching element (40) are connected in series between an electrical energy source and a ground, wherein the electrical power conversion device comprises: a short-circuit current detection unit (92; 93; 110; 111) configured to detect whether one of the upper arm switching element (30) and the lower arm switching element (40) is subject to a short-circuit fault or not, the short-circuit current detection unit includes: a detection unit (96; 97; 112; 113) configured to turn off one of the switching elements, with a gate signal of one of the switching elements at a low level, and to turn on another of the switching elements, with a gate signal of the other of the switching elements at a high level, and to detect an induced voltage generated when a current flows through a collector-side wiring connected to a collector side of the other of the switching elements; and a comparison unit (96; 97; 112; 113) configured to compare the induced voltage detected by the detection unit with a predetermined threshold voltage, characterized by the fact that The detection of the induced voltage is carried out between a detection point on the collector-side wiring, which has a higher potential than a collector detection point on the collector side of the other of the switching elements, and an emitter detection point of the other of the switching elements.

Description

BACKGROUND OF THE INVENTION 1. Field of the invention

[0001] The invention relates to an electrical power conversion device and in particular to an electrical power conversion device that is capable of performing a detection to determine whether a current flowing through a switching element is a short-circuit current or not. 2. Description of the related technology

[0002] It is desirable that a rapid detection process is used to determine whether a current flowing through a switching element is a short-circuit current or not.

[0003] For example, publication JP 2001 - 169 533 A discloses a Rogowski coil designed to detect the rate or velocity of change of a main current flowing through the switching element of an electrical power conversion device.

[0004] When placing the Rogowski coil in series within the switching element, the induced current generated in the Rogowski coil is a time-differentiated current. Therefore, it can be detected within a short time whether the current flowing through the switching element is a short-circuit current or not. False detection occurs if an external magnetic field is present in the Rogowski coil as noise or interference. However, using a Rogowski coil requires creating a loop within the current path of the object being measured, which increases costs and the required installation area.

[0005] As a generic prior art document that discloses an electrical power conversion device according to the preamble of the independent claim, US 6,304,472 B1 is known. This document discloses an electrical power conversion system in which, in order to detect a current with high accuracy, an inductor is connected in series with a main terminal of a switching element, and a voltage generated at both ends of the inductor during the switching period is integrated using an integration circuit.

[0006] Further prior art is known from publication EP 2 469 710 A1 and the subsequently published publication DE 11 2015 003 784 T5. SUMMARY OF THE INVENTION

[0007] The invention is aimed at providing an electrical power conversion device that enables rapid detection of whether a current flowing through a switching element is a short-circuit current or not, without the need for an externally attached Rogowski coil.

[0008] According to the invention, an electrical power conversion device is provided as defined by the independent claim. Further developments and embodiments of the electrical power conversion device according to the invention are defined in the dependent claims.

[0009] An electrical power conversion device according to one aspect of the disclosure comprises a switching element, a collector-side wiring connected to a collector side of the switching element, an emitter-side wiring connected to an emitter side of the switching element, a detection circuit configured to detect an induced voltage generated in the collector-side wiring or the emitter-side wiring when a current flows through the collector-side wiring or the emitter-side wiring, and a comparator circuit configured to compare the induced voltage with a predetermined threshold voltage.

[0010] The electrical power conversion device according to the aspect of the disclosure detects the induced voltage generated by a wiring inductance of the emitter-side wiring or the collector-side wiring when current flows through the emitter-side wiring connected to the emitter side of the switching element or the collector-side wiring connected to the collector side of the switching element. The wiring inductance of the emitter-side wiring and the wiring inductance of the collector-side wiring are generally referred to as parasitic inductance for an inductance component of a wiring material and a wiring arrangement and do not constitute an additional inductance element such as an external Rogowski coil.

[0011] Generally, the inductance component of the wiring ranges from approximately several nH (nanohenries) to approximately a few dozen nH. However, if the switching element is subjected to a short circuit, a large current flows within a short time interval, resulting in a high value due to the time differential of the current. For example, if a short-circuit current of 10 kA flows for 1 µs, the induced voltage generated by the 5 nH inductance component of the wiring becomes 50 V, which can be adequately detected. Accordingly, by detecting the induced voltage generated by the wiring inductance of the emitter-side or collector-side wiring and comparing it to the predetermined threshold voltage, it can be quickly determined whether the current flowing through the switching element is the short-circuit current or not, even without an externally attached Rogowski coil.

[0012] In the electrical power conversion device according to the aspect of the disclosure, the detection circuit can be configured to detect the induced voltage generated in the emitter-side wiring between an emitter detection point on the emitter-side wiring on the emitter side of the switching element and a first detection point on the emitter-side wiring that has a lower potential than the emitter detection point. In the electrical power conversion device according to the aspect of the disclosure, the detection circuit can be configured to detect the induced voltage generated in the emitter-side wiring between an emitter detection point on the emitter side of the switching element and a first detection point on the emitter-side wiring that has a lower potential than the emitter detection point.The detection circuit shall be configured to detect the induced voltage generated in the collector-side wiring between a collector detection point on the collector-side wiring on the collector side of the switching element and a second detection point on the collector-side wiring that has a higher potential than the collector detection point.

[0013] In the electrical power conversion device according to the aspect of the disclosure, the switching element is subject to a current flow from an electrical energy source on the collector side to a ground on the emitter side. In this respect, the detection of the induced voltage, which is generated by the wiring inductance of the emitter-side wiring, is carried out between the emitter detection point on the emitter-side wiring of the switching element and the first detection point, which is located further towards ground and has a lower potential than the emitter detection point.Additionally, the detection of the induced voltage, generated by the wiring inductance of the collector-side wiring, is performed between the collector detection point on the collector-side wiring of the switching element and the second detection point, which is located further towards the electrical power source and has a higher potential than the collector detection point. When the induced voltage detection points are arranged on the wiring as described above, it can be quickly determined whether the current flowing through the switching element is a short-circuit current or not.

[0014] In the electrical power conversion according to the aspect of the disclosure, the detection circuit can be configured to detect the induced voltage generated in the collector-side wiring between a second detection point, which has a higher potential than a collector detection point on the collector-side wiring of the switching element, and an emitter detection point of the switching element. In a case where, based on the induced voltage generated in the collector-side wiring, it is detected whether the current flowing through the switching element is the short-circuit current or not, for example, when the switching element is switched on, the switching element has a low level of an ON resistance.If, for example, the second detection point is located near the collector detection point, the potential of the second detection point will be almost equal to the potential of the emitter detection point of the switching element. If, for example, a connection for another purpose is already provided on the collector side of the switching element, the existing connection can be used as the second detection point as is, which is advantageous because no special connection needs to be used for detecting the induced voltage.

[0015] The electrical power conversion device according to the aspect of the disclosure may additionally include an output circuit configured to output a predetermined signal based on the result of a comparison by the comparator circuit. In the electrical power conversion device according to the aspect of the disclosure, the output circuit may be configured to output the signal when the induced voltage is higher than the predetermined threshold voltage. By setting the induced voltage to the predetermined threshold voltage at a time when the current flowing through the switching element is the short-circuit current, it is possible to detect, based on the comparison between the induced voltage and the predetermined threshold voltage, whether the current flowing through the switching element is the short-circuit current or not.Because the predetermined signal is output when the induced voltage is higher than the predetermined threshold voltage, it can be quickly detected that the current flowing through the switching element is the short-circuit current.

[0016] The electrical power conversion device according to the aspect of the disclosure may additionally include a gate monitoring circuit configured to monitor a gate voltage of the switching element. The signal may be masked if the gate voltage measured by the gate monitoring circuit does not reach or falls below an ON threshold voltage of the switching element. The predetermined signal outputs the result of the comparison between the induced voltage and the predetermined threshold voltage, and therefore the predetermined signal may be erroneously output when, for example, the switching element transitions from OFF to ON. However, according to this configuration, the erroneous output of the predetermined signal during the transition of the switching element from OFF to ON can be prevented.

[0017] The electrical power conversion device according to the aspect of the disclosure may further comprise an inverter arm in which an upper-arm switching element and a lower-arm switching element are connected in series between an electrical power source and ground, and an upper-arm short-circuit current detection circuit or circuit configured to detect a short-circuit current flowing through the upper-arm switching element based on the induced voltage generated in the emitter-side wiring of the upper-arm switching element. The electrical power conversion device according to the aspect of the disclosure may further comprise an inverter arm in which an upper-arm switching element and a lower-arm switching element are connected in series between an electrical power source and ground, and a lower-arm short-circuit current detection circuit or circuit configured to detect a short-circuit current flowing through the upper-arm switching element based on the induced voltage generated in the emitter-side wiring of the upper-arm switching element.which is configured to detect a short-circuit current flowing through the lower arm switching element based on the induced voltage generated in the emitter-side wiring of the lower arm switching element.

[0018] The electrical power conversion device according to the aspect of the disclosure may further comprise an inverter arm in which an upper-arm switching element and a lower-arm switching element are connected in series between an electrical power source and a ground, and an upper-arm short-circuit current detection circuit or circuit configured to detect a short-circuit current flowing through the upper-arm switching element based on the induced voltage generated in the collector-side wiring of the upper-arm switching element. The electrical power conversion device according to the aspect of the disclosure may further comprise an inverter arm in which an upper-arm switching element and a lower-arm switching element are connected in series between an electrical power source and a ground, and a lower-arm short-circuit current detection circuit or circuit configured to detect a short-circuit current flowing through the upper-arm switching element based on the induced voltage generated in the collector-side wiring of the upper-arm switching element.which is configured to detect a short-circuit current flowing through the lower arm switching element based on the induced voltage generated in the collector-side wiring of the lower arm switching element.

[0019] To detect a short circuit in one of the two switching elements that make up the inverter arm, it is possible to determine whether the current flowing through the other switching element is excessive when the switching element subject to the short circuit is switched OFF and the other switching element is switched ON. In this respect, the upper arm short-circuit current detection circuit is used when, based on the induced voltage generated in the collector-side wiring of the upper arm, it is detected whether the current flowing through the upper arm switching element is the short-circuit current. The lower arm short-circuit current detection circuit is used when, based on the induced voltage generated in the collector-side wiring of the lower arm, it is detected whether the current flowing through the lower arm switching element is the short-circuit current.Similarly, the upper-arm short-circuit current detection circuit is used to detect, based on the induced voltage generated in the emitter-side wiring of the upper arm, whether the current flowing through the upper-arm switching element is the short-circuit current or not. The lower-arm short-circuit current detection circuit is used to detect, based on the induced voltage generated in the emitter-side wiring of the lower arm, whether the current flowing through the lower-arm switching element is the short-circuit current or not. In this way, it can be detected accurately and quickly whether the current flowing through the switching element is the short-circuit current or not.

[0020] According to the electrical power conversion device of the aspect of the disclosure, it can be quickly detected whether the current flowing through the switching element is the short-circuit current or not, even without the Rogowski coil being externally attached. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Features, advantages and technical and industrial significance of exemplary embodiments of the invention are described below with reference to the accompanying drawings, in which identical / similar reference numerals denote identical / similar elements, and for which the following applies: Fig. Figure 1A is a circuit configuration representation illustrating a wiring inductance of an emitter-side wiring and a detection point of this in an inverter arm serving as an electrical power conversion device according to an embodiment of the invention; Fig. 1B is a flat structural view at the time of an implementation of the configuration that is in Fig. 1A is illustrated; Fig. 1C is a side view of a connection page at the time the configuration is implemented, which is in Fig. 1A is illustrated; Fig. 1D is a side view of the side opposite the connection side at the time the configuration is implemented, which is in Fig. 1A is illustrated; Fig. 2A is a circuit configuration representation illustrating a wiring inductance of a collector-side wiring and a detection point of this in the inverter arm, which serves as the electrical power conversion device according to the embodiment of the invention; Fig. 2B is a flat structural view at the time of an implementation of the configuration that is in Fig. 2A is illustrated; Fig. 2C is a side view of the connection side at the time the configuration was implemented, which is in Fig. 2A is illustrated; Fig. 2D is a side view of the side opposite the connection side at the time the configuration is implemented, which is in Fig. 2A is illustrated; Fig. Figure 3A is a circuit configuration representation relating to a lower-arm short-circuit current detection unit at a time when short-circuit current detection is carried out by using the wiring inductance of the emitter-side wiring in the inverter arm, which serves as the electrical power conversion device according to the embodiment of the invention; Fig. 3B, the Fig. 3A corresponds to a circuit configuration representation with reference to an upper-arm short-circuit current detection unit; Fig. 4A is a timing diagram illustrating the operating state of each element at a time during normal operation without a short-circuit fault of an upper-arm switching element in the circuit configuration shown in Fig. 3A is illustrated; Fig. 4B, which in contrast to Fig. 4A is a time diagram illustrating the operating state of each element at a time of short-circuit fault of the upper arm switching element; Fig. 5A is a circuit configuration representation relating to a lower-arm short-circuit current detection unit at a time when the short-circuit current detection is carried out by using the wiring inductance of the collector-side wiring in the inverter arm, which serves as the electrical power conversion device according to the embodiment of the invention; Fig. 5B, the Fig. 5A corresponds to a circuit configuration representation with reference to the upper arm short-circuit current detection unit; Fig. Figure 6A is a timing diagram illustrating the operating state of each element during normal operation without the short-circuit disturbance of the upper-arm switching element in the circuit configuration shown in Fig. 5A is illustrated; Fig. 6B, which in contrast to Fig. 6A is a time diagram illustrating the operating state of each element at the time of the short-circuit fault of the upper arm switching element; Fig. Figure 7 is a timing diagram illustrating the possibility of a short-circuit current detection malfunction in the circuit configuration shown in Fig. 5A is illustrated; Fig. 8A, which with Fig. 5A is related to a circuit configuration representation relating to the lower arm short-circuit current detection unit at a time when the malfunction of the short-circuit current detection is prevented by the use of a gate voltage detection; Fig. 8B, the Fig. 8A corresponds to a circuit configuration representation with reference to the upper arm short-circuit current detection unit; Fig. Figure 9A is a timing diagram illustrating the operating state of each element, including a mask signal, during normal operation without the upper-arm switching element short-circuit disturbance in the circuit configuration shown in Fig. 8A is illustrated; and Fig. 9B, which, unlike Fig. 9A is a timing diagram illustrating the operating state of each element, including the mask signal, at the time of the upper arm switching element's short circuit fault. DETAILED DESCRIPTION OF EXAMPLES OF EXECUTION

[0022] An embodiment of the invention is described in detail below with reference to the accompanying drawings. In the following description, a single inverter arm is described as an electrical power conversion device. This is an example for descriptive purposes, and the electrical power conversion device can be configured to include a plurality of inverter arms. For example, an electrical power conversion device configured to include three inverter arms connected in parallel can be used in a drive circuit for a three-phase rotating electric machine.

[0023] The inverter arm is a circuit device in which an upper arm switching element and a lower arm switching element are connected in series between an electrical power source and ground. The potential of ground is lower than the potential of the electrical power source, but it is not limited to 0 V. For example, the potential of ground can be negative.

[0024] In the following description, an insulated-gate bipolar transistor (IGBT) is used as the switching element. This is an example for illustrative purposes, and the switching element could just as easily be a metal-oxide-semiconductor field-effect transistor (MOSFET).

[0025] In the electrical power conversion device, an induced voltage is detected that is generated in a collector-side or emitter-side wiring circuit when a current flows through it. This allows for a rapid detection of whether the current flowing through the switching element is a short-circuit current. The use of a switching element with an attached or connected sensing terminal is a known method for detecting whether the current flowing through the switching element is a short-circuit current. The sensing terminal extracts an extremely small fraction of the current flowing through the switching element.For example, whether the current flowing through the switching element is the short-circuit current is detected by taking a current equivalent to one-thousandth of the current flowing through the switching element from the sensing terminal and comparing it to a predetermined threshold current. However, this method does not allow for rapid detection because the sensitivity is low due to a weak sensing current, and it takes time for the sensing current to rise to the threshold current. In this respect, according to one embodiment of the invention, the electrical power conversion device detects the induced voltage generated in the collector-side wiring or the emitter-side wiring when the current flows through the collector-side wiring or the emitter-side wiring.

[0026] For the sake of simplicity, the following description distinguishes between an emitter side and a collector side with respect to wiring inductance, and between an upper arm side and a lower arm side with respect to a short-circuit current detection unit. Wiring inductance is naturally present on both the emitter and collector sides. Furthermore, in a structure where the upper arm and lower arm switching elements are connected in series, it is often unknown which of the switching elements is subject to a short-circuit fault. In a case where, for example, it is structurally apparent that the short-circuit fault frequently occurs on either the upper arm or the lower arm side, it is conceivable that a single short-circuit current detection unit will suffice.Except in such a case, the short-circuit current detection unit can be installed on either the upper arm side or the lower arm side.

[0027] In the following description, the same reference symbols are used to refer to corresponding elements in all drawings, and multiple descriptions are omitted.

[0028] Fig. 1A to 1D and Fig. Figures 2A to 2D are drawings illustrating wiring inductances of wiring and detection points of these in an inverter arm 10, which serves as the power conversion device.

[0029] The inverter arm 10 is a circuit device in which an upper arm switching element 30 and a lower arm switching element 40 are connected in series between the electrical energy source, represented by VH, and the ground, represented by GND.

[0030] Each of the upper arm switching element 30 and the lower arm switching element 40 is an N-channel IGBT, and a diode between the collector and the emitter is a reverse-flow or freewheeling diode. The reverse-flow or freewheeling diode can be a diode integrated on the same chip as the IGBT, such as an RC IGBT. Alternatively, the reverse-flow or freewheeling diode can be implemented independently and separately from an IGBT main body.

[0031] Each of the upper arm switching element 30 and the lower arm switching element 40 exhibits the wiring inductance of the emitter-side wiring and the wiring inductance of the collector-side wiring. The wiring inductance of the emitter-side wiring is described first, and the wiring inductance of the collector-side wiring is described afterward.

[0032] Fig. 1A to 1D show the respective wiring inductances of the emitter-side wiring and the respective detection points of these from the upper arm switching element 30 and the lower arm switching element 40. Fig. 1A is a circuit configuration representation of inverter arm 10. Fig. 1B is a planar structural view of inverter arm 10. Fig. 1C is a side view of a connection side of the inverter arm 10, and Fig. 1D is a side view of the side opposite the connection side. The connection side refers to a side where one terminal 12, connected to the electrical power source and represented by P, the other terminal 16, connected to ground and represented by N, and an output terminal 20, represented by O, are located.

[0033] The inverter arm 10 has the following elements connected in series in one direction, from the electrical power source represented by VH to ground represented by GND, in the following order: electrical power source VH, terminal 12, collector-side wiring 14 of the upper arm switching element 30, upper arm switching element 30, an intermediate busbar 22, lower arm switching element 40, emitter-side wiring 18 of the lower arm switching element 40, the other terminal 16, and GND. The intermediate busbar 22 is a wiring configuration in which the emitter-side wiring of the upper arm switching element 30 and the collector-side wiring of the lower arm switching element 40 are integrated. The output terminal 20 of the inverter 10 is from the intermediate power supply or...Busbar 22 pulled out.

[0034] Terminal 12, the collector-side wiring 14 of the upper arm switching element 30, the intermediate busbar 22, the emitter-side wiring 18 of the lower arm switching element 40, the other terminal 16, and the output terminal 20 are conductive plates. With the exception of the intermediate busbar 22, these are flat plates.

[0035] As it is in Fig. 1B, Fig. 1C and Fig. As illustrated in Figure 1D, the inverter arm 10 has a compact physical structure utilizing the intermediate busbar 22, which has a stepped structure with lower and upper stages or sections. In other words, the emitter (E) of the upper arm switching element 30 is connected to a lower surface of the upper stage of the intermediate busbar 22, and the collector (C) of the lower arm switching element 40 is connected to an upper surface of the lower stage of the intermediate busbar 22. The collector (C) of the upper arm switching element 30 is connected to an upper surface of the collector-side wiring 14, and the terminal 12 extends from the collector-side wiring 14.The emitter (E) of the lower arm switching element 40 is connected to a lower surface of the emitter-side wiring 18, and the other terminal 16 is pulled out of the emitter-side wiring 18. The output terminal 20 is pulled out of the intermediate current or busbar 22.

[0036] In Fig. 1A and Fig. 1B is a wiring inductance 50 on the emitter side of the upper arm switching element 30, an inductance component of a portion of the intermediate current or busbar 22 at the emitter-side wiring of the upper arm switching element 30. The induced voltage is generated when current flows through it. The detection of the induced voltage is carried out between an emitter detection point 52 of the intermediate current or busbar 22 on the emitter side of the upper arm switching element 30 and a first detection point 54 of the intermediate current or busbar 22 on the output terminal 20 side. The potential of the first detection point 54 with respect to the wiring inductance 50 is lower than the potential of the emitter detection point 52. As shown in Fig. As illustrated in Figure 1B, the first detection point 54 can be set up on the side of the intermediate current or busbar 22 from the output terminal 20.

[0037] A wiring inductance 60 on the emitter side of the lower arm switching element 40 is an inductance component of the emitter-side wiring 18. The induced voltage is generated when current flows through it. The detection of the induced voltage is carried out between an emitter detection point 62 of the lower arm switching element 40 on the emitter-side wiring 18 and a first detection point 64 of the emitter-side wiring 18 on the side of the other terminal 16. The potential of the first detection point 64 with respect to the wiring inductance 60 is lower than the potential of the emitter detection point 62. As shown in Fig. As illustrated in Figure 1B, the first detection point 64 can be set up on the emitter-side wiring 18 from the other terminal 16.

[0038] The respective connections and detection points according to Fig. The 1A terminals are arranged from the one with the highest voltage to the one with the lowest voltage as follows. In other words, they are arranged in the order of terminal 12, emitter detection point 52 on the intermediate current / busbar 22, first detection point 54 on the intermediate current / busbar 22, output terminal 20, emitter detection point 62 on the emitter-side wiring 18, first detection point 64 on the emitter-side wiring 18, and the other terminal 16.

[0039] The emitter detection point 52 on the intermediate busbar 22 and the first detection point 54 on the intermediate busbar 22 correspond to detection units that detect the induced voltage of the emitter-side wiring of the switching element 30, and each of these has a corresponding connecting line or terminal. Similarly, the emitter detection point 62 on the emitter-side wiring 18 and the first detection point 64 on the emitter-side wiring 18 correspond to detection units that detect the induced voltage of the emitter-side wiring of the switching element 40, and each of these has a corresponding connecting line or terminal. The corresponding connecting line or terminal serves to connect to a terminal of a circuit that compares the magnitude of the induced voltage with a predetermined threshold voltage.A metallic wire for wire bonding or the like can be used as the appropriate connecting cable or terminal.

[0040] In Fig. 1A and Fig. In Figure 1B, the wiring inductances 50 and 60 are shown by dashed lines. This serves to demonstrate that the wiring inductances 50 and 60 are not individual elements added in the form of an external Rogowski coil or the like, but rather inductance components inherent to the wiring. The same applies to the following illustration.

[0041] The wiring inductance of the collector-side wiring is described below. Fig. 2A to 2D, the Fig. Drawings 1A to 1D show the respective wiring inductances of the collector-side wiring and the respective detection points of these from the upper arm switching element 30 and the lower arm switching element 40. Fig. 2A is a circuit configuration representation of inverter arm 10. Fig. 2B is a planar structural view of inverter arm 10. Fig. 2C is a side view of the connection side of inverter arm 10, and Fig. 2D is a side view of the side opposite the connection side.

[0042] In Fig. 2A and Fig. 2B is a wiring inductance 70 on the collector side of the upper arm switching element 30, an inductance component of the collector-side wiring 14. The induced voltage is generated when current flows through it. Additionally, a wiring inductance 80 on the collector side of the lower arm switching element 40 is an inductance component of a portion of the intermediate current or busbar 22 at the collector-side wiring of the lower arm switching element 40. The induced voltage is generated when current flows through it.

[0043] The detection of the induced voltage can be carried out by voltage detection between the detection points at both ends of the respective wiring inductances 70, 80, as described with reference to Fig. 1A and Fig. The content described in 1B. The collector detection point of the upper arm switching element 30 and a second detection point 72, which has a higher potential than the collector detection point, are used for detecting the induced voltage on the collector side of the upper arm switching element 30. The collector detection point of the lower arm switching element 40 and a second detection point 82, which has a higher potential than the collector detection point, are used for detecting the induced voltage on the collector side of the lower arm switching element 40.

[0044] The detection of the induced voltage on the collector side of the upper-arm switching element 30 can be performed between the second detection point 72 and an emitter detection point 74 of the upper-arm switching element 30, instead of using the collector detection point and the second detection point 72. The upper-arm switching element 30 is connected between the second detection point 72 and the emitter detection point 74, but the inductance component in the upper-arm switching element 30 is lower in value than the inductance component of the collector-side wiring 14. Accordingly, the potential of the emitter detection point 74 is essentially equal to the potential of the collector detection point of the upper-arm switching element 30.

[0045] Likewise, the detection of the induced voltage on the collector side of the lower arm switching element 40 can be carried out between the second detection point 82 and an emitter detection point 84 of the lower arm switching element 40, instead of using the collector detection point and the second detection point 82.

[0046] The respective connections and detection points according to Fig. The 2A are arranged from the one with the highest voltage to the one with the lowest voltage as follows. These are arranged in the order of terminal 12, the second detection point 72 on the collector-side wiring 14, the emitter detection point 74 of the upper arm switching element 30, the output terminal 20, the second detection point 82 on the intermediate current or busbar 22, the emitter detection point 84 of the lower arm switching element 40 and the other terminal 16.

[0047] The following describes a circuit configuration of the electrical power conversion device with an attached or connected short-circuit current detection unit, which utilizes the wiring inductance's rapid detection capability for current rate of change, as well as a timing diagram relating to its operation. During a control operation for the inverter arm 10, which is located in Fig. 1 and Fig. As illustrated in Figure 2, one switching element is subjected to OFF operation when the other switching element is subjected to ON operation. An appropriate dead time or standstill time is provided to prevent through current flow and to ensure that the ON-OFF timing of one and the ON-OFF timing of the other do not coincide.

[0048] Either the upper arm switching element 30 or the lower arm switching element 40, connected in series, is subject to short-circuit faulting in two modes. One mode involves one of the switching elements being subject to short-circuit faulting when the other switching element is in the OFF position, and the other involves one of the switching elements being subject to short-circuit faulting when the other switching element is in the ON position. Short-circuit fault detection is performed by the switching element on the side without the fault. However, in the first mode, the switching element responsible for detection remains OFF when the short-circuit fault occurs, and therefore the detection is delayed by the dead time or standstill time until this switching element is switched ON.In the latter method, the switching element that is to perform the detection is already in an ON state when the short-circuit fault occurs, and thus the short-circuit fault detection can be carried out quickly.

[0049] In the following description, the short-circuit fault is detected by determining whether the current flowing through the switching element, which is in the ON position, is the short-circuit current or not. Additionally, the high current-change rate inductance of the wiring is used to detect changes in current, thus enabling rapid detection. In other words, the short-circuit fault of the upper-arm switching element 40 is detected by using the wiring inductance of the lower-arm switching element 40 for short-circuit current detection. The short-circuit fault of the lower-arm switching element 40 is detected by using the wiring inductance of the upper-arm switching element 30 for short-circuit current detection.

[0050] Fig. 3A and Fig. Figure 3B shows circuit configuration representations of electrical power conversion devices 10a, 10b with attached or connected short-circuit current detection unit, which utilize the wiring inductance of the emitter-side wiring. Fig. 3A is a circuit configuration representation at the time of detection of the short-circuit fault of the upper arm switching element 30, and Fig. Figure 3B is a circuit configuration representation at the time of detection of the short-circuit fault of the lower arm switching element 40. It is unknown whether the upper arm switching element 30 or the lower arm switching element 40 is subject to the short-circuit fault, and therefore the electrical power conversion device has a configuration in which the configuration that is in Fig. 3A is illustrated, and the configuration shown in Fig. As illustrated in 3B, the two configurations are combined. However, the following description details the features of the two short-circuit fault detection configurations separately.

[0051] In the electrical power conversion device 10a, which is in Fig. As illustrated in Figure 3A, a control circuit 90 is a circuit connected to a gate of the upper-arm switching element 30 of the inverter arm 10 and performs ON-OFF control on, or with respect to, the upper-arm switching element 30. A short-circuit current detection unit 92 comprises a control circuit 94 and a comparator 96 for short-circuit current detection. The short-circuit current detection unit 92 is a lower-arm short-circuit current detection unit located on the side of the lower-arm switching element 40 and detects the short-circuit current flowing through the lower-arm switching element 40 when the upper-arm switching element 30 is subject to a short-circuit disturbance. The control circuit 94 is a circuit of the same content as the control circuit 90, and the control circuit 94 is connected to a gate of the lower arm switching element 40 and performs an ON-OFF control on the respective.with reference to the lower arm switching element 40. A gate resistor 98 is a resistive element that adjusts the gate resistance of the lower arm switching element 40 to a suitable value. A similar gate resistor 99 (see . Fig. 3B) is also set up in the control circuit 90, but the gate resistor 99 is in Fig. 3A not illustrated. A rotating electric machine 100 is an example of a load of the electrical power conversion device 10a. A smoothing capacitor 102 is a capacitive element that suppresses voltage and current fluctuations between terminal 12 and the other terminal 16 of the inverter arm 10.

[0052] When the inverter arm 10 is operating normally, current flows between the switching element and the rotating electric machine 100. At this time, however, the current is limited by the inductance component of the rotating electric machine 100, and therefore the current change rate (di / dt) is relatively low. If the switching element is subject to a short-circuit fault, on the other hand, current flows directly from the smoothing capacitor 102 into the switching element, and therefore the current change rate (di / dt) is much higher, in some cases approximately 1000 times higher than during normal operation. Accordingly, the operation of the inverter arm 10 must be stopped by quickly detecting the short-circuit fault of the switching element.

[0053] In Fig. 3A, the upper arm switching element 30 is subject to the short-circuit fault and therefore an external gate signal is input to the control circuit 90 of the upper arm switching element 30 at a low level. An external gate signal input to the control circuit 94 of the lower arm switching element 40 is at a high level. The low level is a gate voltage at which the switching element is switched OFF, and the high level is a gate voltage at which the switching element is switched ON.

[0054] The comparator 96 for short-circuit current detection is a comparison unit that compares the induced voltage generated in the wiring inductance 60 with a predetermined threshold voltage V. REFThe comparator 96 for short-circuit current detection is also an output unit that outputs a predetermined signal based on the result of the comparison. The first detection point 64 of the wiring inductance 60 is connected to a reference voltage source that provides the predetermined threshold voltage V. REF The input terminal 64, which provides the short-circuit current detection signal, is connected to a positive input terminal of the comparator 96, which is one of two input terminals of the comparator 96. Additionally, the emitter detection point 62 of the wiring inductor 60 is connected to a negative input terminal. The comparator 96 outputs a low level when the voltage between the first detection point 64 and the emitter detection point 62 is lower than the threshold voltage V. REF, and outputs the Hi level when the voltage between the first detection point 64 and the emitter detection point 62 is equal to or higher than the threshold voltage V REF is. If the voltage between the first detection point 64 and the emitter detection point 62 is equal to or higher than the threshold voltage V REF The current flowing through the lower arm switching element 40 is an excessive short-circuit current.

[0055] The threshold voltage V REF can be determined as the induced voltage generated when the short-circuit current flows through the wiring inductance 60. This induced voltage is {(10 kA / µs) × 5 nH} = 50 V if the rate of change (di / dt) of the short-circuit current is 10 kA / µs and the magnitude of the wiring inductance 60 is 5 nH. If the threshold voltage V REFFor example, if the voltage is 30 V, the comparator 96 outputs the high level when the short-circuit current flows through the lower arm switching element 40. In this way, the comparator 96, which is located on the side of the lower arm switching element 40, detects the short-circuit current flowing through the lower arm switching element 40 when the upper arm switching element 30 is subject to a short-circuit fault.

[0056] Although the wiring inductance 60, which has a value of 5 nH, was described above as an example, the required value Lds of the wiring inductance for short-circuit current detection is obtained as follows. The required value Lds of the wiring inductance for short-circuit current detection is Lds > {Vdmin / (di / dt)sc} if the comparator 96 has a minimum detection voltage Vdmin and the current rate of change at the time of a short circuit is equal to (di / dt)sc. Lds > {30 V / (10 kA / µs)} is 3 nH if (di / dt)sc = 10 kA / µs and Vdmin = threshold voltage V REF = 30 V applies. In the example described above, Lds is equal to 5 nH, and therefore this condition is met. In another example, an Lds of approximately 1 nH will suffice if Vdmin = threshold voltage V. REF= 10 V applies. This value lies within a range that can be adequately covered by the wiring inductance without the need for an additional Rogowski coil for detection.

[0057] The control circuit 64 takes an AND gate from the external gate signal of an external control circuit (not illustrated) and an inverse signal of an output signal from the comparator 96 and inputs this to the gate of the lower-arm switching element 40 as the lower-arm gate voltage LG. When the output signal of the comparator 96 is at a low level, the lower-arm switching element 40 is driven accordingly in response to the external gate signal. When the external gate signal is at a high level, the lower-arm gate voltage LG reaches a high level, and the lower-arm switching element 40 is switched ON. Conversely, when the output signal of the comparator 96 is at a high level, the lower-arm gate voltage LG reaches a low level regardless of the external gate signal, and the lower-arm switching element 40 is switched OFF.In this way, the flow of the excessive short-circuit current through the lower arm switching element 40 is detected, and the lower arm switching element 40 is quickly switched OFF and protected.

[0058] Fig. Figure 3B shows a circuit configuration at the time of detection of the short-circuit fault of the lower arm switching element 40. Fig. 3B is the same in its basic configuration. Fig. 3A, and corresponding elements are illustrated such that one is added to their reference symbols. Here, the external gate signal input to a control circuit 91 of the lower arm switching element 40 is at the low level, and the external gate signal input to a control circuit 95 of the upper arm switching element 30 is at the high level.

[0059] The wiring inductance 50 on a portion of the intermediate current or busbar 22, corresponding to the emitter-side wiring of the upper-arm switching element 30, is used for short-circuit fault detection. A short-circuit current detection unit 93 is an upper-arm short-circuit current detection unit located on the side of the upper-arm switching element 30 and detects the short-circuit current flowing through the upper-arm switching element 30 when the lower-arm switching element 40 is subject to short-circuit fault. The first detection point 54 of the wiring inductance 50 is connected via the reference voltage source, which provides the threshold voltage V. REFfor short-circuit current detection, is connected to a positive-side input terminal of a comparator 97, which represents one of two input terminals of the comparator 97 in the short-circuit current detection unit 93. Additionally, the emitter detection point 52 of the wiring inductor 50 is connected to a negative-side input terminal.

[0060] In this configuration, the induced voltage in the wiring inductor 50 is generated when the lower arm switching element 40 is short-circuited and an excessive current flows through the upper arm switching element 30. When an output signal from the comparator 97 reaches the high level, upon detection, the upper arm gate voltage UG reaches the low level regardless of the external gate signal, and the upper arm switching element 30 is switched off. In this way, the flow of the excessive short-circuit current through the upper arm switching element 30 is detected, and the upper arm switching element 30 is quickly switched off and protected.

[0061] There Fig. 3A and Fig. 3B if they are similar with regard to a configurational or structural effect, the configurational or structural effect will be determined with reference to Fig. 4A and Fig. 4B and Fig. 3A is described in more detail as a representative drawing. Fig. Figure 4A is a time diagram illustrating a state of each element at a time of normal operation of the inverter arm 10 without the short-circuit disturbance of the upper arm switching element 30. Fig. Figure 4B is a timing diagram illustrating the state of each element at the time of a short-circuit fault of the upper-arm switching element 30. In each of the drawings, the horizontal axis represents time, and the vertical axis represents a level or voltage state of each element. The topmost section on the vertical axis represents a level of an external upper-arm gate signal input to the drive circuit 90, and the second section from the top represents a level of an external lower-arm gate signal input to the drive circuit 94. The third section from the top represents a level of the upper-arm gate voltage UG, and the fourth section from the top represents a level of the lower-arm gate voltage LG. The fifth section from the top represents a voltage level of V. CEbetween the collector and the emitter of the lower arm switching element 40, and the lowest section represents an output level of the comparator 96.

[0062] In Fig. According to section 4A, in which inverter arm 10 is in normal operation, time t1 to time t7 is a period in which the external upper-arm gate signal is at a low level, and time t2 to time t6 is a period in which the external lower-arm gate signal is at a high level. The period from time t1 to time t2 and the period from time t6 to time t7 are the dead and standstill times, respectively. The upper-arm gate voltage UG changes with a delay corresponding to the circuit processing delay of the drive circuit 90 relative to the external upper-arm gate signal. Fig. 4A is the upper-arm gate voltage UG at the low level from time t1 to time t7 when the circuit processing delay is negligible, and the upper-arm switching element 30 is switched OFF during this period. Similarly, the lower-arm gate voltage LG changes with a delay corresponding to the circuit processing delay of the drive circuit 94 relative to the external lower-arm gate signal. Fig. 4A is the lower arm gate voltage LG from time t2 to time t6 at the high level when the circuit processing delay time is negligible, and the lower arm switching element 40 is switched ON during this period.

[0063] The voltage V CEBetween the collector and the emitter of the lower arm switching element 40 is a voltage resulting from the multiplication of an ON resistance by an ON current when the lower arm switching element 40 is switched ON. In an example, the rate of change of the ON current is (di / dt) approximately 10 A / µs. If the wiring inductance 60 has a value of 5 nH, the induced voltage generated in the wiring inductance 60 is equal to {(10 A / µs) × 5 nH} = 50 mV. The voltage V CE The voltage between the collector and the emitter increases due to / around this induced voltage.

[0064] The comparator 96 compares this induced voltage with the threshold voltage V. REF The induced voltage is 50 mV from time t2 to time t6. Comparator 96 has a low-level output when the threshold voltage V is exceeded. REFThe voltage of comparator 96 is at 30 V, and it is determined that the short-circuit current does not flow through the lower arm switching element 40.

[0065] Fig. Figure 4B is a time diagram at the time the short-circuit fault occurs in the upper-arm switching element 30 at time t3. The content of the horizontal axis and the content of the vertical axis are the same as in Fig. 4A. In this case, the inverter arm 10 is in normal operation, the voltage is V CEThe voltage between the collector and the emitter is 50 V, and the output of comparator 96 is at low level until just before time t3. As soon as the short-circuit disturbance occurs in the upper-arm switching element 30 at time t3, the induced voltage in the wiring inductor 60 is generated at approximately the same time as the short-circuit current flows through the lower-arm switching element 40. The induced voltage is {(10 kA / µs) × 5 nH} = 50 V if the rate of change (di / dt) of the short-circuit current is 10 kA / µs and the magnitude of the wiring inductor 60 is 5 nH.

[0066] The induced voltage is at time t3, at which the induced voltage and the threshold voltage V REF to be compared with each other, as in Fig. 4A, equivalent to 50V. The comparator 96 has a high-level output when the threshold voltage V is exceeded. REFthe comparator is at 30 V, and it is determined that the short-circuit current flows through the lower arm switching element 40.

[0067] The comparator 96 has a circuit processing delay, and therefore the high level is output to the control circuit 94 at time t4. The control circuit 94 also has a circuit processing delay, and therefore the lower arm switching element 40 is forcibly switched OFF at time t5. Time t5 is a time before time t6, at which the external lower arm gate signal is switched OFF, and therefore the lower arm switching element 40 is protected from impairment or damage by the short-circuit current. The period after time t6 is equal to that which is in Fig. 4A is illustrated. As described above, the wiring inductance 60 has a high capability of detecting a current change rate, and therefore it can perform short-circuit current detection in a fast manner.

[0068] Fig. 5A and Fig. 5B are circuit configuration representations of electrical power conversion devices 10c, 10d with attached or connected short-circuit current detection unit, which use the wiring inductance of the collector-side wiring. Fig. 5A is a circuit configuration representation at the time of detection of the short-circuit fault of the upper arm switching element 30, and Fig. Figure 5B is a circuit configuration representation at the time of detection of the short-circuit fault of the lower arm switching element 40. As it is with reference to Fig. 3A and Fig. As described in 3B, it is unknown whether the upper arm switching element 30 or the lower arm switching element 40 is subject to short-circuit disturbance, and therefore features of the two configurations for short-circuit disturbance detection are described separately below.

[0069] The electrical power conversion device 10c according to 5A, which detects the short-circuit fault of the upper arm switching element 30, differs from the electrical power conversion device 10a, which is described in Fig. Figure 3A illustrates this. Here, the wiring inductance 80 is used for short-circuit current detection on a portion of the intermediate current or busbar 22, corresponding to the collector-side wiring of the lower arm switching element 40. The emitter detection point 84 of the wiring inductance 80 is connected via the reference voltage source, which provides the threshold voltage V. REFfor short-circuit current detection, is connected to a positive-side input terminal of a comparator 112, which represents one of two input terminals of the comparator 112 for short-circuit current detection, which is included in the short-circuit current detection unit 110. The second detection point 82 of the wiring inductor 80 is connected to a negative-side input terminal. A diode 106 is a rectifier element that voltaically isolates the inverter arm 10, which operates at a high voltage, from the short-circuit current detection unit 110, and has a cathode connected to the intermediate current or busbar 22 and an anode connected to a CL terminal of the short-circuit current detection unit 110. The CL terminal is the negative-side input terminal of the comparator 112. The other elements are the same as in Fig. 3A.

[0070] If the wiring inductance 60 is used in the emitter-side wiring, which is described with reference to Fig. As described in section 3A, a voltage difference equivalent to the induced voltage generated in the wiring inductance 60 is generated between a ground-side reference voltage of the inverter arm 10 and a ground-side reference voltage of the short-circuit current detection unit 92. However, by using the wiring inductance 80 in the collector-side wiring, the ground-side reference voltage of the inverter arm 10 and the ground-side reference voltage of the short-circuit current detection unit 110 can be made equal to each other, thus improving the accuracy of the short-circuit current detection. Furthermore, in a case where the diode 106 is pre-installed, for example, for the purpose of monitoring a collector potential of the lower-arm switching element 40, no special connecting line from the second detection point 82 is required.In particular, when the electrical power conversion device is configured to include a plurality of inverter arms, the connecting line from the second detection point 82 is numerically multiple, and the lack of need for this contributes to a reduction in the size and cost of the electrical power conversion device as a whole.

[0071] Fig. 5B is a circuit configuration representation at the time of detection of the short-circuit fault of the lower arm switching element 40. Fig. 5B is the same in its basic configuration. Fig. 5A, and corresponding elements are illustrated such that one is added to the reference numerals of these. The electrical power conversion device 10d, which detects the short-circuit fault of the lower arm switching element 40, differs from the electrical power conversion device 10b, which is shown in Fig. Figure 3B illustrates this. Here, the wiring inductance 70 of the collector-side wiring 14 of the upper-arm switching element 30 is used for short-circuit current detection. The emitter detection point 74 of the wiring inductance 70 is connected via the reference voltage source, which provides the threshold voltage V. REFfor short-circuit current detection, is connected to a positive-side input terminal of a comparator 113, which represents one of two input terminals of the comparator 113 for short-circuit current detection, which is included in a short-circuit current detection unit 111. The second detection point 72 of the wiring inductor 70 is connected to a negative-side input terminal. A diode 107 is a rectifier element that voltaically isolates the inverter arm 10, which operates at a high voltage, from the short-circuit current detection unit 111, and has a cathode connected to the collector-side wiring 14 and an anode connected to a CU terminal of the short-circuit current detection unit 111. The CU terminal is the negative-side input terminal of the comparator 113. The other elements are the same as in Fig. 3B.

[0072] Advantages of using the wiring inductance 70 in the collector-side wiring instead of the wiring inductance 50 in the emitter-side wiring, which, with reference to Fig. The content described in 3B is identical to the content described with reference to Fig. 5A is described.

[0073] There Fig. 5A and Fig. 5B if they are similar with regard to a configurational or structural effect, the configurational or structural effect will be determined with reference to Fig. 6A and Fig. 6B and Fig. 5A is described as a representative drawing. Fig. 6A and Fig. 6B are drawings that Fig. 4A and Fig. 4B. The content of the horizontal axis and the content of the vertical axis are the same as in Fig. 4A and Fig. 4B.

[0074] In Fig. 6A, according to which the inverter arm 10 is in normal operation, the voltage V CE The voltage between the collector and the emitter of the lower arm switching element 40 results from the ON resistance being multiplied by the ON current when the lower arm switching element is switched ON. If the ON current has a rate of change of (di / dt) = 10 A / µs and the wiring inductance 80 has a value of 5 nH, the induced voltage generated in the wiring inductance 80 is {(10 A / µs) × 5 nH} = 50 mV. The voltage V CE The voltage between the collector and the emitter increases due to / around this induced voltage.

[0075] The comparator 112 compares this induced voltage with the threshold voltage V. REF The induced voltage is 50 mV from time t2 to time t6. Comparator 112 has a low-level output when the threshold voltage V is exceeded. REFThe voltage of comparator 112 is at 30 V, and it is determined that the short-circuit current does not flow through the lower arm switching element 40.

[0076] In Fig. 6B, which shows a time at which the short circuit in the upper arm switching element 30 occurs at time t3, the inverter arm 10 is in normal operation, the voltage V CE The voltage between the collector and the emitter is 50 mV, and the output of comparator 112 is at low level until just before time t3. As soon as the short-circuit disturbance occurs in the upper-arm switching element 30 at time t3, the induced voltage in the wiring inductor 80 is generated at approximately the same time as the short-circuit current flows through the lower-arm switching element 40. The induced voltage is {(10 kA / µs) × 5 nH} = 50 V if the rate of change (di / dt) of the short-circuit current is 50 kA / µs and the value of the wiring inductor 80 is 5 nH.

[0077] The induced voltage at time t3, at which the induced voltage and the threshold voltage V REF The voltage to be compared is 50 V. The comparator 112 has a high-level output when the threshold voltage V is exceeded. REF The voltage of comparator 112 is at 30 V, and it is determined that the short-circuit current flows through the lower arm switching element 40.

[0078] As described above, the use of the wiring inductance 80 in the collector-side wiring leads to timing diagrams similar to those in Fig. 4A and Fig. 4B are, and effects similar to those achieved by using the wiring inductance 60 in the emitter-side wiring.

[0079] In the preceding description, the comparators 112, 113 compare the induced voltages generated in the wiring inductors 80, 70 with the threshold voltage V. REFIn the circuit configuration diagrams shown in Fig. 5A and Fig. As illustrated in Figure 5B, comparators 112 and 113 detect the voltage between the collector and the emitter of the switching element. Depending on the extent of a time delay between the external gate signal and the gate signal applied to the switching element, comparators 112 and 113 may detect the short-circuit current incorrectly, and the short-circuit current detection may fail or function poorly.

[0080] Fig. Figure 7 shows the possibility of faulty detection with respect to comparator 112. Fig. Figure 7 represents time on the horizontal axis and the level or voltage state of each element on the vertical axis. The topmost section on the vertical axis represents the level of the external lower-arm gate signal. The second section from the top represents the level of a command signal with respect to the lower-arm gate voltage LG of the lower-arm switching element 40, and the third section from the top represents the level of the actual lower-arm gate voltage LG in the lower-arm switching element 40. The fourth section from the top represents the voltage state V. CE between the collector and the emitter of the lower arm switching element 40, and the lowest section represents an output level of the comparator 112.

[0081] In Fig. 7 is time t1 equals t1 in Fig. 6A and Fig. 6B, and represents the time at which the external lower-arm gate signal rises from the low level to the high level. Time t10 is the time at which the command signal, with respect to the lower-arm gate voltage LG of the lower-arm switching element 40, begins to rise after the external lower-arm gate signal has risen to the high level. Time t2 is equal to t2 in Fig. 6A and Fig. 6B. The time from t1 to time t10 is an internal circuit processing delay time of the drive circuit 94. The time from time t10 to time t2 is a gate capacitance charging time of the lower arm switching element 40.

[0082] The lower-arm gate voltage LG of the lower-arm switching element 40 begins to rise from the low level at time t10 and increases in response to a constant at a time of gate capacitance charging. The rise is complete at time t2. This causes the voltage V CEThe voltage between the collector and the emitter of the lower arm switching element 40 begins to fall at time t10 and ends at time t2. Time t12, which is a time before time t2 is reached, is the time at which the lower arm gate voltage LG reaches an ON threshold voltage, at which the lower arm switching element 40 switches from OFF to ON. Time t2, which is reached after a significant progression from time t12, corresponds to the time at which the voltage V CE between the collector and the emitter of the lower arm switching element 40 is sufficiently brought into a saturation state.

[0083] The comparator 112 detects the voltage between the second detection point 82 and the emitter detection point 84. Even if no current flows through the wiring inductance 80, the high level is output accordingly until time t11, at which the voltage V CEbetween the collector and the emitter of the lower arm switching element 40 to the threshold voltage V REF The voltage drop is determined with respect to the induced voltage. This high-level output represents a state in which the lower-arm switching element 40 undergoes a transition from OFF to ON, and does not represent short-circuit current detection. Depending on the magnitude of the circuit processing delay between the external gate signal and the gate signal applied to the switching element, the comparator 112 outputs the high level despite the absence of short-circuit current flow through the lower-arm switching element 40, thus resulting in erroneous short-circuit current detection. When erroneous detection occurs in the comparator 112, the drive circuit for the lower-arm switching element 40 either does not function or functions poorly.

[0084] Fig. 8A and Fig. Figure 8B shows a circuit configuration of an electrical power conversion device that prevents the malfunction of the short-circuit current detection unit that may occur during the transition of the switching element from OFF to ON. Fig. 8A is a circuit configuration representation of an electrical power conversion device 10e that prevents the malfunction of a short-circuit current detection unit 120 that detects the short-circuit fault of the upper arm switching element 30. Fig. Figure 8B is a circuit configuration representation of an electrical power conversion device 10f that prevents the malfunction of a short-circuit current detection unit 121 which detects the short-circuit fault of the lower arm switching element 40.

[0085] Fig. 8A, which concerns the detection of the short-circuit fault of the upper arm switching element 30, differs from Fig. 6A, wherein a gate monitoring circuit 124 is provided in the short-circuit current detection unit 120 and a mask section 126 is provided in a drive circuit 122, which is included in the short-circuit current detection unit 120. The other elements are the same as in Fig. 6A.

[0086] The gate monitoring circuit 124, integrated into the short-circuit current detection unit 120, directly detects the gate voltage of the lower arm switching element 40. The detected gate voltage is then monitored and checked against a predefined gate ON threshold voltage to ensure it is equal to or higher than the ON threshold voltage, and a result is then output. Direct detection refers to the detection of the actual gate voltage in the lower arm switching element 40, rather than an external gate signal. Furthermore, the gate voltage command signal output by the control circuit 122 in response to the external gate signal is also detected.Regarding a monitoring result output method, the Hi level is output when the detected gate voltage is lower than the ON threshold voltage, and the Lo level is output when the detected gate voltage is equal to or higher than the ON threshold voltage.

[0087] The mask section 126, which is implemented in the control circuit 122, masks or hides an output signal of the comparator 112 by using the output signal from the comparator 112 and an output signal from the gate monitoring circuit 124 when the output signal from the gate monitoring circuit 124 is at a high level. Masking the output signal of the comparator 112 means that a circuit outputs a low level by hiding the output signal of the comparator 112, even when the output signal of the comparator 112 is at a high level.

[0088] When mask section 126 is used, the signal from comparator 112 remains in the control circuit 122 until time t12. Fig. 7 on a low-level signal, even if the output signal of comparator 112 is at a high level. Accordingly, the malfunction of the short-circuit current detection unit 120 is prevented.

[0089] Fig. 8B, which concerns the detection of the short-circuit fault of the lower arm switching element 40, is the same in the basic configuration Fig. 8A, and corresponding elements are illustrated such that one is added to the reference numerals of these. Here, a gate monitoring circuit 125 is set up in the short-circuit current detection unit 121, and a mask section 127 is set up in a control circuit 123, which is included in the short-circuit current detection unit 121. The content regarding the gate monitoring circuit 125 and the content regarding the mask section 127 are similar to those regarding the gate monitoring circuit 124 and the mask section 126, which are shown in Fig. 8A are illustrated, and therefore a detailed description of these is omitted.

[0090] There Fig. 8A and Fig. 8B if they are similar with regard to a configurational or structural effect, the configurational or structural effect will be determined with reference to Fig. 9A and Fig. 9B and Fig. 8A is described as a representative drawing. Fig. 9A and Fig. 9B are drawings that Fig. 6A and Fig. 6B corresponds. The horizontal axis represents as in Fig. 6A and Fig. 6B represents time, but times t10 and t12, which refer to Fig. The elements described in section 7 are added here. The vertical axis represents an operating level of the stress state of each element, as described in Fig. 6A and Fig. 6B is the case, but the operating level of a mask signal is added in the lowest section thereof. Additionally, the waveform corresponds to the actual lower-arm gate voltage LG of the lower-arm switching element 40 and the waveform to the voltage V. CE between the collector and the emitter of the lower arm switching element 40 with reference to Fig. 7 described course patterns.

[0091] When inverter arm 10 is in normal operation, the high level is output as the output of comparator 112, as shown in Fig. 9A is illustrated until the voltage V CE between the collector and the emitter of the lower arm switching element 40 to the threshold voltage V REF The voltage drops, which is set with respect to the induction voltage. With reference to this faulty detection of the comparator 112, the mask signal outputs the high level until time t12. Time t12 is the time at which the gate voltage of the lower arm switching element 40 rises so that it reaches the ON threshold voltage. In this way, the malfunction of the short-circuit current detection unit 120 is prevented when the lower arm switching element 40 undergoes the transition from OFF to ON during the normal operation of the inverter arm 10.

[0092] Similarly, in Fig. 9B, which shows a time at which the inverter arm 10 is subject to the short-circuit fault at time t3, prevents the malfunction of the short-circuit current detection unit 120 when the lower arm switching element 40 undergoes the transition from OFF to ON. Then, after time t3, the short-circuit fault detection can be carried out quickly, since the wiring inductance 80 has the high capability to detect a current change rate, as described in reference to Fig. 6B is described.

[0093] An electrical power conversion device (10a; 10b; 10c; 10d; 10e; 10f) comprises: a switching element (30; 40); a collector-side wiring (14) connected to a collector side of the switching element; an emitter-side wiring (18) connected to an emitter side of the switching element; a detection circuit (96; 97; 112; 113) configured to detect an induced voltage generated in the collector-side wiring or the emitter-side wiring when a current flows through the collector-side wiring or the emitter-side wiring; and a comparison circuit (96; 97; 112; 113) configured to compare the induced voltage detected by the detection circuit with a pre-determined predetermined threshold voltage.

Claims

[1] Electrical power conversion device (10a; 10b; 10c; 10d; 10e; 10f) with an inverter arm (10) in which an upper arm switching element (30) and a lower arm switching element (40) are connected in series between an electrical energy source and a ground, wherein the electrical power conversion device comprises: a short-circuit current detection unit (92; 93; 110; 111) configured to detect whether one of the upper arm switching element (30) and the lower arm switching element (40) is subject to a short-circuit fault or not, the short-circuit current detection unit includes: a detection unit (96; 97; 112; 113) configured to turn off one of the switching elements, with a gate signal of one of the switching elements at a low level, and to turn on another of the switching elements, with a gate signal of the other of the switching elements at a high level, and to detect an induced voltage generated when a current flows through a collector-side wiring connected to a collector side of the other of the switching elements; and a comparison unit (96; 97; 112; 113) configured to compare the induced voltage detected by the detection unit with a predetermined threshold voltage, characterized by , that The detection of the induced voltage is carried out between a detection point on the collector-side wiring, which has a higher potential than a collector detection point on the collector side of the other of the switching elements, and an emitter detection point of the other of the switching elements. [2] Electrical power conversion device according to claim 1, characterized by : an output unit (96; 97; 112; 113) that is configured to output a predetermined signal based on a result of the comparison by the comparator unit. [3] Electrical power conversion device according to claim 2, characterized by , that the output unit outputs the signal when the induced voltage is higher than the predetermined threshold voltage. [4] Electrical power conversion device according to claim 2 or claim 3, characterized by : a gate monitoring circuit (124; 125) configured to monitor one gate voltage of the other of the switching elements, the signal is masked if the gate voltage measured by the gate monitoring circuit does not reach an ON threshold voltage of the other switching element. [5] Electrical power conversion device according to claim 1, characterized by : an inverter arm (10) in which an upper-arm switching element (30) and a lower-arm switching element (40) are connected in series between the electrical energy source and ground; and at least one of: an upper-arm short-circuit current detection unit (93; 111) configured to detect whether a current flowing through the upper-arm switching element is a short-circuit current or not, based on the induced voltage generated in the collector-side wiring of the upper-arm switching element; and a lower-arm short-circuit current detection unit (92; 110) configured to detect whether a current flowing through the lower-arm switching element is a short-circuit current or not, based on the induced voltage generated in the collector-side wiring of the lower-arm switching element.

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