DE102020216412B3 - Vehicle power circuit, inverter circuit and vehicle electric drive - Google Patents

Abstract

A vehicle power circuit with at least one transistor whose source terminal is connected to a parasitic line inductance has a differential feedback element that feeds back the parasitic line inductance to a gate of the transistor. A first voltage limiting circuit is provided between a reference potential connection of a driver circuit and a supply potential (M) of the vehicle power circuit (LS). A first supply-potential-related P element includes the first voltage limiting circuit. The voltage limiting circuit is designed as a series connection of a diode and a zener diode. As a result, the reference potential is electrically connected to the negative supply potential when the reference potential of the driver circuit in question is below the negative supply potential.

Description

Numerous components within a vehicle are operated electrically. This applies in particular to the traction drive. In this case, an accumulator provides the supply voltage, which is in the form of direct current. In order to set the power delivered to the component (or the power fed back from the component), the accumulator voltage is clocked using a power circuit. As a result, the power can be adjusted by means of the pulse duty factor of the clocked switching.

Power semiconductors such as transistors are used for clocked switching, which ideally have a very steep current edge in order to keep switching losses as low as possible. On the other hand, rapid switching events, i. H. due to steep current edges, a high voltage that is induced due to parasitic line inductances, which can also result in switching overvoltages on the transistor.

The pamphlet DE 100 32 196 A1 describes a protection circuit for a MOSFET whose gate is connected to ground via an RC element and which has a capacitive coupling element between drain and source.

Document US 2012/0 032 710 A1 describes a transistor driver unit with a feedback section that feeds back to the control input of the transistor.

The pamphlet DE 197 44 848 A1 describes a circuit with inductive feedback from a transistor to be switched to a driver of the transistor.

It is an object of the invention to show a possibility with which the voltage induced by line inductances can be limited or adjusted,

This object is achieved by the control circuit for power semiconductors, which is part of the vehicle power circuit, by the inverter circuit, further features, embodiments, properties and advantages result from the dependent claims, the description and the figure.

It is proposed to equip a drive circuit for power semiconductors, which is part of a vehicle power circuit, with a negative feedback network, by means of which the course of the edges (current and voltage) can be adapted, limited or adjusted. Therefore, a power circuit with a constant, proportionally acting ("P-element II", cf. 1 ) and/or a discontinuous proportionally acting ("P-element III", cf. 1 ) and/or a differentially acting ("D-element: I", cf. 1 ) feedback element suggested.

The feedback is based on the fact that a voltage is induced during the current edge at each section of a commutation loop or a parasitic inductance within the commutation loop. The entire commutation loop is the sum of the individual parasitic sections or inductances. This voltage is fed back to the gate of the respective semiconductor for each feedback element, either via a suitable galvanic tap of a parasitic section of the commutation loop via an impedance coupling between the load path and the drive path, and/or via an inductive coupling between the entire commutation loop, and thus acts on its cause opposite. i.e. the switching edge can be regulated. A commutation loop includes a switch and connections of the switch and connections leading to the switch, which form (parasitic) inductances. As a result, the switching losses can be minimized. On the other hand, the dielectric strength of the power semiconductors can be optimally utilized and the influence of parameter scatter is reduced or minimized.

The negative feedback network described here, which is formed by a differential feedback element and in particular by one or more P elements, is connected to at least one power semiconductor, which carries out the clocked switching. As a result, this acts on the switch or the transistors, which as a result have a switching behavior (taking into account line inductances) that can be set by means of the negative feedback network. Furthermore, embodiments are presented in which the negative feedback network is represented by at least one differential feedback element, while further embodiments additionally have one or more P elements.

A vehicle power circuit with at least one half-bridge is therefore described, which has a high-side switch and low-side switch, each with at least one transistor. These switches are connected in series and thus form at least one half-bridge. The switches each have a source, ie a source region which faces a (negative) supply potential. A parasitic line inductance connects to the respective source connection of the switches. This can be formed by electrical connections such as conductor tracks and/or by the source ce inductance within the transistor of the switch, ie inductances within the source region of the transistor or the component which forms the switch, such as electrical connections within the component. In principle, this applies to all electrical connections within the commutation loop or the individual components of the switch or transistor. Because the wire inductance is not in the form of a dedicated component such as an inductor and occurs even when it is not desired, the wire inductance can be referred to as parasitic wire inductance. The parasitic line inductance is part of the equivalent circuit diagram in particular, whereby the equivalent circuit diagram, as is also shown in 1 is used, reflects inductances of the leads or conductor tracks of the interconnection and in particular within the transistor component. Furthermore, the parasitic line inductance can reflect the inductance of components such as shunt resistors and can also be influenced by the basic arrangement or the design, ie the spatial arrangement of the components and the electrical connections and their exact design. If necessary, other connections such as wiring and/or conductor tracks and the like are also possible, which are also included in the line inductance. Collectively, this is called the parasitic inductance of the commutating cell. This parasitic inductance of the commutation cell is used for the purpose of driving or for feedback of the current edge within the respective drive circuit (feedback paths I, II and III of the respective drive circuit of a transistor as in 1 shown) and can be tapped directly electrically in the area of the source, among other things. This is an impedance coupling or a galvanic coupling of the main current or load current path and the current path of the drive circuit. In addition, but also exclusively, the parasitic inductance of the commutation loop can be compensated via an inductive coupling in the respective feedback path (reference symbols I, II, III of the 1 ) of the respective feedback element (P, D element) can be used and, for example, be designed as a conductor track loop or similar.

The control circuit for power semiconductors has at least one differential feedback element (or a differential feedback path). This couples back the voltage drop caused by the current edge to the gate of the respective transistor, either galvanically coupled to the parasitic line inductance in the source path of the respective transistor and/or via an inductive coupling with the entire commutation inductance. A passive negative feedback results, which has a positive influence on the switching behavior.

The differential feedback element results in a D element that reacts to the change in the switching edge and thus reduces overshooting of the turn-off overvoltage caused by a current edge that is too steep. The relevant feedback loop or the relevant feedback element is in the 1 represented by the reference symbol I. The overvoltage as a result of the current edge is limited by the feedback in the control circuit and thus counteracts its cause and limits the steepness of the current edge. As a result, the current edge and in particular its progression can be set via the wiring, namely via the differential feedback element or generally via the negative feedback network.

The differential feedback element can be viewed as part of the negative feedback network, which is formed in the control circuit of the power semiconductor. As mentioned, further feedback elements such as P elements can also be provided in the negative feedback network. The feedback circuit and also the P circuits, if present, can be referred to as a negative feedback loop. These are part of the negative feedback network.

The differential feedback element may include or be formed by a feedback capacitor. This capacitor connects the parasitic line inductance of the respective source of the transistor to its gate. In addition, an inductive coupling with the commutation inductance can be formed in the same path, which increases the effect. This option for implementing negative feedback requires only a few additional components and can be implemented in a simple manner, in particular, as a passive control circuit that does not have a microcontroller or the like. Furthermore, the control circuit described here can also or specifically be implemented with a shunt, which is designed for current measurement in the source path of the LS switch.

One aspect is that the negative feedback network is formed for both transistors of each half-bridge. In this case, both transistors (including the electrical connection of the relevant transistor) of each half bridge each have a source with a respective parasitic line inductance. In the equivalent circuit diagram, this line inductance is connected to the source of the transistor element or connected downstream of it. In other words, both transistors of the half-bridge are connected via respective parasitic line inductances (this relates in particular to parasitic line inductances in the equivalent circuit diagram of the transistor). The respective path can also be be inductively coupled to the entire commutation inductance.

The respective line inductances are connected to a gate of the relevant transistor via a respective differential feedback element. In this case, the source of the high transistor is connected via a parasitic line inductance which is connected to its gate via a differential feedback element. The low-side transistor has a source which is connected via a parasitic line inductance, with a corresponding (further) differential feedback element connecting this line inductance to the gate of the low-side transistor. The feedback elements (galvanically and/or inductively coupled) are not necessarily of the same design, rather they are adapted to the line inductances or the coupling, which can be different for different transistors (low side/high side).

In this case, the source connection of each transistor is connected via a respective parasitic line inductance to the differential feedback element, which in turn connects the relevant line inductance to the gate of the corresponding transistor. The connection between the feedback element and the gate is preferably direct (i.e. without any other intervening component). The same preferably also applies to the line inductance and the relevant transistor.

Furthermore, an embodiment is shown in which each half-bridge has a center connection that is located between the two transistors (high side/low side). The high-side transistor may be connected (or may be directly connected) to a center terminal of the half-bridge via a first parasitic line inductance. The center connection is connected to the gate of the high-side transistor via a first differential feedback element. The middle connection is just one possibility for a tap, to which the (differential) feedback element is connected; in principle, the (differential) feedback element can be provided at any position of the phase outlet. The source of the low-side transistor is connected to a first supply potential of the power circuit via a second parasitic line inductance. This supply potential can be a negative supply potential or ground, for example. The end of the second parasitic line inductance, which is remote from the source of the low-side transistor, is connected to the gate of the low-side transistor via a second differential feedback element. In this case, the source of the low-side transistor is connected directly to the differential feedback element via the second line inductance, which in turn connects the line inductance directly to the gate of the transistor. A second supply potential can be provided, which is connected (in particular via a further parasitic line inductance) to the drain or drain connection of the high-side transistor. The half-bridge can thus be connected to a first and to a second supply potential. The second supply potential can be a positive supply potential. A high-voltage supply voltage, for example approximately 400 V, 600 V or 800 V, can be present between the two supply potentials, or a supply voltage of approximately 48 V or 42 V or 24 V can lie between the two supply potentials.

The differential feedback element, i. H. the feedback element of the low-side transistor, can connect the connection point between the second and the third parasitic power inductance to the source terminal of the low-side transistor. In this case, the second parasitic line inductance can be designed together with the feedback element (for example via suitable dimensioning) in order to generate a desired switching behavior of the low-side transistor in the event of a switching event.

As mentioned, in addition to the differential feedback element, which forms a negative feedback loop as a D element (where this applies to each control, i.e. to both transistors), a further negative feedback loop (where this in turn applies to each control, i.e. to both transistors), can be provided, which is implemented as a P-element. The relevant feedback loop is in the 1 marked with the reference symbol II. On the one hand, the negative feedback is also implemented via an impedance coupling between the main current or load current path and the current path of the drive circuit, with the current path of the drive circuit representing the actual, fundamentally necessary path between gate driver and switch. The common path is the parasitic line inductance in the source path of the control and is responsible for the effect/function. On the other hand, the parasitic inductance of the entire commutation loop can additionally, but also exclusively, be used via an inductive coupling and be designed, for example, as a conductor track loop or the like. Here, the first P-element couples back the source terminal (which is connected to the relevant transistor via a line inductance) to the gate of the transistor. In particular, the source of the transistor is fed back to its gate via the connected line inductance and the subsequent first P-element. This preferably applies to both transistors of a half-bridge. It can thus be provided a first P-member, which on the first line inductance is connected to the source terminal of the high-side transistor, and this line inductance (indirectly) feeds back to the gate.

A second P element can be provided, which is connected to the second parasitic line inductance and thereby (indirectly) feeds back the source of the low-side transistor to its gate via this line inductance. The first P element or both P elements can be provided between a driver circuit or driver circuits on the one hand and one of the transistors or both transistors on the other hand. The P element can be implemented by one or more resistors, which provide the feedback in the sense of a feedback P element.

In each case, the galvanically coupled feedback can be supplemented or replaced by an inductively coupled one. In this case, in the corresponding path of the P element (reference symbol II of 1 ) a suitable inductive coupling is realized by a conductor track loop or similar.

The vehicle power circuit is preferably designed in such a way that the first driver circuit has a gate connection and a reference potential connection. The second driver circuit preferably also has a gate connection and a reference potential connection. In this case, the reference potential connections are the negative connections compared to the gate connections. In this case, the reference potential relates to a source-side connection of the driver circuits. The reference potential connection of the first driver circuit is connected via a first source resistor (which is relevant to the realization of the negative feedback loop marked with the reference symbol III, ie the supply-potential-related P element, but is not relevant to the negative feedback loop marked with the reference symbol II) to the end of the connected parasitic line inductance, which faces away from the first transistor. The reference potential connection of the second driver circuit is connected via a second source resistor to the end of a parasitic line inductance which is connected to the source connection of the second transistor.

The gate connection of the first driver circuit is connected to the gate of the first transistor via a first gate resistor. The gate connection of the second driver circuit is connected to the gate of the second transistor via a second gate resistor. The source resistances and the gate resistances are thus connected in series between the driver circuits and the transistors. The first P-gate includes the first source resistance and the first gate resistance. The second P-gate includes the second source resistance and the second gate resistance. As mentioned, the source resistors and the gate resistors are connected in different connections between the driver circuits and the associated transistors. The first P-element forms a feedback network. This couples the source connection of the first transistor back to its gate, with the feedback taking place via the first driver circuit. The second P-gate feeds back the source of the second transistor to its gate, with the feedback passing through the second source resistor, the second gate resistor, and the second driver circuit. The source of the first transistor is thus fed back via the source resistor, the first driver circuit and the first gate resistor (in that order). The source of the second transistor is fed back to the gate of the second transistor (in that order) via the second source resistor, the second driver circuit, and the second gate resistor. The connection between the driver circuits and the associated transistors is therefore two-pole, with the gate and source resistances being at different potentials of the driver circuit with the associated transistor.

Further embodiments provide that the drive circuit for power semiconductors of the vehicle power circuit has a further P element, which represents a further feedback loop. This feedback loop exhibits a discontinuous behavior and only reacts or feeds back when an adjustable threshold of the turn-off overvoltage or steepness of the current edge is exceeded. The negative feedback is implemented via an impedance coupling between the main current or load current path and the current path of the negative feedback path. The common path is the parasitic line inductance in the source path of the MOSFET, which, however, must not be in the current path of the actual control between the driver and the MOSFET. The negative feedback on the control of the MOSFET in turn acts via an impedance coupling between the negative feedback path and a part of the current path of the control circuit, namely the common source resistance. In addition, but also exclusively, the parasitic inductance of the entire commutation loop can be used via an inductive coupling and can be designed, for example, as a conductor track loop or the like. This type of negative feedback only works via the wiring after the voltage drop at the correspondingly tapped, parasitic inductance exceeds a certain threshold. The threshold depends on the parasitic inductance itself, the steepness of the current edge and the wiring. The Unsteady behavior of the further P element, which represents the further feedback loop, exhibits a discontinuous behavior. The discontinuous behavior is realized by the (first) voltage limiting circuit. The voltage limiting circuit is provided between a reference potential connection of the gate driver of one of the transistors and a supply potential of the vehicle power circuit. In this case, the supply potential is ground or the negative supply potential of the power circuit. The vehicle power circuit thus has a further P element, which is also referred to as the first supply-potential-related P element. The first voltage limiting circuit is part of the first supply-potential-related P element. A second voltage limiting circuit can be provided, so that both transistors and their associated gate driver circuits are each provided with a supply voltage potential-related P element.

Accordingly, further embodiments of the power circuit include a first and a second voltage limiting circuit. The first voltage limiting circuit connects a reference potential connection of a first gate driver to a negative supply potential of the vehicle power circuit, in particular to ground. The second voltage limiting circuit connects a reference potential connection of a second gate driver to the negative supply potential of the vehicle power circuit. This results in a further feedback loop for each transistor, which is related to the supply potential.

The voltage limiting circuit can be designed as a series connection of a diode and a zener diode. This is set up to connect the reference potential of the gate driver in question to the negative supply potential (in particular ground) of the vehicle power circuit in a current-conducting manner if the reference potential of the gate driver in question is more than one voltage magnitude below the negative supply potential. Otherwise, the voltage limiting circuit will not conduct current. In this case, the diode is preferably connected in the reverse direction and the Zener diode provided in series with it in the flow direction. This results in a current flow when the reference potential of the relevant gate driver has a negative potential compared to the negative supply potential, and when the amount of voltage across the voltage limiting circuit, i. H. the amount of voltage between the reference potential and the negative supply potential is more than the sum of the forward voltage of the diode and the zener voltage of the zener diode. If the reference potential of the relevant gate driver has a positive potential compared to the negative supply potential, then the diode blocks.

The term gate driver is to be understood here as synonymous with the term gate driver circuit. The supply-potential-related feedback loops or P-members mentioned serve to avoid negative voltage peaks that result from self-induction on a connected inductive consumer (for example an electrical machine).

An inverter circuit is also described that includes one or more vehicle power circuits as described herein. The inverter circuit includes a number of the half-bridges or a number of the power circuits, with a center connection being provided in each of the half-bridges between the high-side transistor and the low-side transistor. The resulting center connections form phase connections of the inverter circuit. They are set up to be connected to phases of an electrical machine, in particular to a synchronous machine.

Furthermore, a vehicle electric drive is described which has an inverter circuit or power circuit as mentioned here. The electric drive also includes an electric machine, the phase connections of the electric machine being connected to the phase connections of the inverter circuit.

The inverter circuit or the power circuit or the vehicle electric drive can also be designed for feedback in order to feed back the power of a connectable or connected electric machine (to the supply potentials). The vehicle drive or the inverter circuit preferably has a plurality of half-bridges which together form a B6C bridge or a B12C bridge or the like.

the 1 serves to explain in more detail embodiments of the power circuit described here, the inverter circuit and the electric drive.

In the 1 is a power circuit LS shown, of which in the 1 a half-bridge with associated driver TH, TL is reproduced. The half-bridge has a series connection of two transistors T1, T2, which are connected to two supply potentials (M and P). Parasitic line inductances Ls1 to Ls6 are shown. These result from the electrical connection or wiring within the power circuit and are formed, for example, by conductor tracks (possibly also connections inside the transistors) and the like, by means of which the similar transistors are connected and connected, or the half-bridges are connected to each other. Furthermore, line inductances result from shunt resistances; this applies in particular to the third line inductance.

The transistors T1 and T2 are each MOSFET transistors, with the associated inverse diode also being shown. The first transistor T1, which can also be referred to as a high-side transistor, is connected to the second transistor T2, which can also be referred to as a low-side transistor, via the parasitic line inductance LS1. In this case, the source of the first transistor T1 is connected to the drain of the second transistor T2. The second line inductance connects to the source of the second transistor T2. The line inductance Ls1 and Ls2 can be provided by the relevant connections or electrical connections such as conductor tracks, but can also be provided by the source resistances within the respective transistor component of the transistors T1, T2, or both. The first line inductance LS1 is connected via a connection point to the transistor T2, on which there is a center connection PA. In the case of an inverter, this center connection PA can be a phase connection to which, for example, a phase connection can be connected to an electrical machine.

The second transistor T2 or its source is followed by a second parasitic line resistance LS2, which can also be formed by the source region of the relevant component, for example. The relevant line inductances L1 to L6 can be part of an equivalent circuit diagram and are not formed by discrete, dedicated components, but are formed by connections, lines and/or areas within a semiconductor.

A first driver TH and a second driver TL are also provided. The first driver TH can also be referred to as a high-side driver, while the driver TL is referred to as a low-side driver. Both drivers are signal sources and in particular voltage sources for controlling the transistors T1 and T2 and are respectively connected to the gate and the source of the respective transistors T1, T2. In this case, the driver circuits TL, TH are connected to the source of the transistors T1, T2 via the associated line inductances. These line inductances are the line inductances LS1, LS2.

In order to provide feedback, in particular a feedback network or a feedback loop thereof, the capacitor RKH is connected to the gate of the transistor T1, to which the driver circuit TH is also connected. Furthermore, the feedback capacitor RKH is connected to the end of the line inductors LS1 that faces away from the transistor T1. The feedback capacitor RKH can thus be connected to a connection of the transistor T1, for example, with the parasitic line resistance LS1 being located between the source region of the transistor and this source connection. Similarly, there is a feedback capacitor RKL between the gate and source of transistor T2. Here too, the feedback capacitor RKL is connected to the end of the line inductance LS2 remote from the transistor T2 and to the gate of the transistor T2. A feedback loop or a feedback element also results here. The feedback capacitors RKH, RKL are differential feedback elements and can also be referred to as D elements. They each form a feedback loop for each transistor T1, T2, so that the switching behavior of the transistors T1, T2 can be adapted in each case by the capacitors RKH, RKL.

The driver circuit TH is connected to the gate or the source of the transistor T1 on the gate side via the resistor RGH and on the source side via the resistor RSH. The driver circuit TL is connected on the gate side via the resistor RGL to the second transistor T2 and on the source side via the resistor RSL.

The respective feedback capacitors RKH, RKL are here provided on the transistor side, so that the resistors RGH, RSH, RGL, RSL are located between the drivers TH, TL and the respective capacitors RKH, RKL. The driver circuits TH, TL are also designed as voltage sources, resulting in a closed circuit that is closed by the source regions of the transistors T1, T2 via the associated line inductances LS1, LS2 and via the resistors RGH, RSH, RGL and RSL .

The resistors RSH, RSL can be referred to as source resistors. The resistors RGH, RGL can be called gate resistors. In this context, the term source resistance means that the relevant driver circuit is connected to the source of the relevant transistor via the relevant resistor. The resistors RGH, RGL are called gate resistors because they connect the driver circuit to the gates of transistors T1, T2. In this context, the resistances referred to as source resistances and gate resistances are resistors (discrete resistive devices mente) between driver circuit and transistor and not resistors within the source or gate area of the respective transistors T1, T2.

The resistors RSH, RSL result in a P element, which feeds back the source of the respective transistors T1, T2 to their gate. This also applies to the resistors RGH, RGL. The resistors RSH, RSL each form a first P element for feeding back a source signal to the gate of the respective transistor. According to another approach, the resistors RSH, RGH form a first P-element for feedback and the resistors RSL, RGL form another P-element for feedback.

Finally, a voltage limiting circuit is provided for each of the two transistors T1, T2 or for the two driver circuits TH, TL. A first voltage limiting circuit for the low side is represented by the diode DL and the zener diode ZL connected in series. The diode DL is reverse-biased and the diode ZL is a zener diode forward-biased in series therewith. The diode DH is connected in the reverse direction with respect to the voltages that usually occur (nominal voltages), while the zener diode ZL is connected in the forward direction (with respect to the usual voltages). The diode and the associated zener diode are connected in series and connected to a first supply potential M. The voltage limiting circuit connects the respective lower driver circuit terminal to the first potential M. The voltage limiting circuits conduct when a negative voltage (relative to potential M) is applied across them, the absolute value of which is greater than the sum of the forward voltage of the respective diode (DH, DL) and the associated zener voltage of the respective zener diode (ZH, ZL). There is a further P element for the high side and for the low side, which feeds back to the gate of the respective transistor T1, T2. It should be noted here that a third line inductance LS3, which connects the line inductance LS2 to the first supply potential M, follows between the end of the second inductance LS2 that faces away from the transistor T2. The transistor T2 is thus connected to the supply potential M (in this order) via the second line inductance and the third line inductance.

The drain of the first transistor T1 is connected to the second supply potential P of the power circuit LS via the fourth line inductance LS4. In this case, the supply potential P is the positive supply potential and the supply potential M is the negative supply potential or ground.

A fifth line inductance L5 leads from the supply potential M to an intermediate circuit capacitor ZK, which is connected to the second supply potential P via a sixth parasitic line inductance LS6. Further half bridges can be connected to the intermediate circuit capacitor (and its line inductance LS6) in order to form an inverter circuit, for example. In particular, an inverter circuit with three or six or also twelve half-bridges can thereby be formed, resulting in a B6C bridge, B12C or the like. Different phases of an electric machine, in particular an electric traction machine of a vehicle, can then be connected to the respective phase connections PA of the different half-bridges or power circuits.

In the 1 feedback loops I, II and III are also shown. For the sake of simplicity, these loops are shown only for the low-side transistor, but alternatively or additionally, corresponding feedback loops can be provided for the high-side transistor.

The feedback loop marked I reacts to the change in the gradient of the current within the commutation cell (cf. transistor T2, Ls2). Feedback is implemented via a tapped parasitic inductance and/or an inductively coupled conductor loop with the commutation loop in the path of the D element represented in this way. The feedback loop marked I implements the differential feedback element.

The feedback loop marked II reacts to the steepness of the current within the commutation cell. Feedback is implemented via a tapped parasitic inductance and/or an inductively coupled conductor loop with the commutation loop in the path of the P element. The feedback loop marked II implements the first P element (proportional element). This can also be referred to as a linear P element.

The feedback loop marked III reacts to the steepness of the current within the commutation cell from a certain limit value (adjustable through the zener diode voltage of the zener diode ZL). Feedback is implemented via a tapped parasitic inductance and/or an inductively coupled conductor loop with the commutation loop in the corresponding section within the path of the (first) P element in combination with the source resistance in the actual control path of the driver circuit TL and the associated impedance coupling. It turns out one non-linear proportional behavior that minimizes the effects of component spreads in the switch or their impact on the current edge, since negative feedback only occurs when a certain threshold value is exceeded, which is only determined by the diode DL and the zener diode ZL in this path. The feedback loop marked III implements the first supply-potential-related P-element (proportional element) and thus in particular a non-linear P-element (proportional element).

Path AA shows an alternative form of the feedback loop marked II (i.e. the first - proportional - P-element), where the first P-element is connected to the source terminal via inductances Ls2 and Ls3. The path AA' corresponds to the path AA for the high side; this results in a connection of resistor RSH via the inductances Ls1', Ls1 to the transistor T1 or to its source. The inductances Ls1' reflect the parasitic inductance of the connection between the two transistors T1, T2.

Furthermore, the inductance Ls1' reflects the parasitic inductance of the connection of the transistor T1 to the phase connection PA.

The one in the 1 The inductances Ls1 and Ls2 shown can be parasitic inductances of electrical connections within the component, ie within the respective switch or transistor T1, T2. The one in the 1 The inductance Ls1' shown can be the parasitic inductance of the line which connects the two transistors T1, T2 to one another (and which also connects the first transistor T1 to the phase connection PA).

An additional inductor can be provided instead of the resistor RGH. This also applies to the resistor RGL.

At the points marked with an X, i.e. between the zener diode ZH, ZL on the one hand and ground on the other hand, there may be another (parasitic) inductance that results from the connection of the respective zener diode.

Claims (11)

Vehicle power circuit having at least one transistor, a parasitic line inductance being connected to a source terminal of the transistor, and the vehicle power circuit having at least one differential feedback element which feeds back the parasitic line inductance to a gate of the transistor, to the source terminal of which the connecting parasitic line inductance, the vehicle power circuit being equipped with at least one first voltage limiting circuit which is provided between a reference potential connection of a driver circuit of one of the transistors and a supply potential (M) of the vehicle power circuit (LS), the vehicle power circuit (LS) has at least one first supply-potential-related P-element, the first voltage-limiting circuit being part of the first supply-potential-related P-element and the voltage-limiting circuit as a series connection of a diode un d of a Zener diode is formed in order to connect the reference potential of the relevant driver circuit to the negative supply potential of the vehicle power circuit in a current-conducting manner when the reference potential of the relevant driver circuit is more than one voltage magnitude below the negative supply potential. Vehicle power circuit after claim 1 , which has a feedback capacitor (RKH, RKL) as a differential feedback element, which connects the parasitic line inductance, which is connected to the source connection of the transistor, to the gate of the transistor. Vehicle power circuit after claim 1 or 2 , which has at least one half-bridge with a high-side transistor and a low-side transistor connected in series thereto, one of which is formed by the transistor, both transistors each having a source connection to which a respective parasitic line inductance is connected , which is connected via a respective differential feedback element to a gate of the relevant transistor. Vehicle power circuit according to one of the preceding claims, which has at least one half-bridge with a high-side transistor and a low-side transistor connected in series thereto, one of which is formed by the transistor, the high-side transistor (T1) is connected to a center connection (PA) of the half-bridge via a first parasitic line inductance (Ls1), the center connection (PA) being connected to the gate of the high-side transistor via a first differential feedback element (RKH) and the source connection of the low-side transistor (T2) is connected to a first supply potential (M) via a second parasitic line inductance (Ls2), the end of the second parasitic line inductance (Lst2) which is connected to the source connection of the low-side transistor ( T2) facing away, is connected to the gate of the low-side transistor via a second differential feedback element (RKL). Vehicle power circuit after claim 4 , wherein the second parasitic line inductance (Ls2) and a subsequent third parasitic line inductance (Ls3) connects the low-side transistor (T2) to the first supply potential (M), the second differential feedback element (RKL) connecting the connection point between the second and the third parasitic line inductance (Ls2, Ls3) connects to the source terminal of the low-side transistor (T2). Vehicle power circuitry according to any one of the preceding claims, wherein the vehicle power circuitry comprises at least a first P-gate connected to the source and the gate of the transistor. Vehicle power circuit after claim 6 , with a first driver circuit (TH), which is connected via a first source resistor (RSH), which is part of the first P-element, to the parasitic line inductance (Ls1), which connects to the high-side transistor and/or with a second driver circuit (TL) which is connected via a second source resistor (RSL) which is part of a second P-gate to the parasitic line inductance (LS2) which connects to the low-side transistor (T2). Vehicle power circuit after claim 7 , wherein the first driver circuit (TH) has a gate connection and a reference potential connection, the reference potential connection being connected via the first source resistor (RSH) to the end of the parasitic line inductance (Ls1) which faces away from the first transistor (T1), the gate connection of first driver circuit is connected to the gate of the first transistor (T1) via a first gate resistor (RGH), and wherein the second driver circuit (TH) has a gate connection and a reference potential connection, the reference potential connection being connected via the second source resistor (RSL) to the end of a parasitic line inductance (Ls2) is connected, which connects to the source connection of the second transistor (T2) and the gate connection of the second driver circuit (TL) is connected to the gate of the second transistor (T2) via a second gate resistor (RGL) and wherein the first P-gate the first source resistance (RSH) and the first Gatew idresistance (RGH), and the second P-path comprises the second source resistance (RSL) and the second gate resistance (RGL). Vehicle power circuit according to one of the preceding claims, which has a first and a second voltage limiting circuit (DH, ZH; DL, ZL), the first voltage limiting circuit (DH, ZH) having a reference potential connection of a first driver circuit (TH) with a negative supply potential of the vehicle - Power circuit connects and the second voltage limiting circuit (DL, ZL) connects a reference potential terminal of a second driver circuit (TH) to the negative supply potential of the vehicle power circuit. Inverter circuit with a vehicle power circuit according to one of the preceding claims, wherein the vehicle power circuit has a plurality of half-bridges, each having a high-side transistor and a low-side transistor connected in series thereto, one of which is formed by the transistor, wherein in each Half-bridge between the high-side transistor (T1) and the low-side transistor (T2) a center connection is provided and the center connections (PA) form phase connections. Vehicle electric drive with an inverter circuit claim 10 and an electric machine, wherein the phase connections of the inverter circuit are connected to phase connections of the electric machine.

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